WorldWideScience

Sample records for ka-band dual-wavelength radar

  1. Sensitivity of S- and Ka-band matched dual-wavelength radar system for detecting nonprecipitating cloud

    Science.gov (United States)

    Vivekanandan, J.; Politovich, Marcia; Rilling, Robert; Ellis, Scott; Pratte, Frank

    2004-12-01

    Remote detection of cloud phase in either liquid, ice or mixed form a key microphysical observation. Evolution of a cloud system and associated radiative properties depend on microphysical characteristics. Polarization radars rely on the shape of the particle to delineate the regions of liquid and ice. For specified transmitter and receiver characteristics, it is easier to detect a high concentrations of larger atmospheric particles than a low concentration of small particles. However, the radar cross-section of a given hydrometeor increases as the transmit frequency of the radar increases. Thus, in spite of a low transmit power, the sensitivity of a millimeter-wave radar might be better than high powered centimeter-wave radars. Also, ground clutter echoes and receiver system noise powers are sensitive functions of radar transmit frequency. For example, ground clutter in centimeter-wave radar sample volumes might mask non-precipitating or lightly precipitating clouds. An optimal clutter filter or signal processing technique can be used to suppress clutter masking its effects and/or enhanced weak cloud echoes that have significantly different Doppler characteristics than stationary ground targets. In practice, it is imperative to investigate the actual performance of S and Ka-band radar systems to detect small-scale, weak cloud reflectivity. This paper describes radar characteristics and the sensitivity of the new system in non-precipitating conditions. Recently, a dual-wavelength S and Ka-band radar system with matched resolution volume and sensitivity was built to remotely detect supercooled liquid droplets. The detection of liquid water content was based on the fact that the shorter of the two wavelengths is more strongly attenuated by liquid water. The radar system was deployed during the Winter Icing Storms Project 2004 (WISP04) near Boulder, Colorado to detect and estimate liquid water content. Observations by dual-wavelength radar were collected in both non

  2. A comparative study of RADAR Ka-band backscatter

    Science.gov (United States)

    Mapelli, D.; Pierdicca, N.; Guerriero, L.; Ferrazzoli, Paolo; Calleja, Eduardo; Rommen, B.; Giudici, D.; Monti Guarnieri, A.

    2014-10-01

    Ka-band RADAR frequency range has not yet been used for Synthetic Aperture Radar (SAR) from space so far, although this technology may lead to important applications for the next generation of SAR space sensors. Therefore, feasibility studies regarding a Ka-band SAR instrument have been started [1][2], for the next generation of SAR space sensors. In spite of this, the lack of trusted references on backscatter at Ka-band revealed to be the main limitation for the investigation of the potentialities of this technology. In the framework of the ESA project "Ka-band SAR backscatter analysis in support of future applications", this paper is aimed at the study of wave interaction at Ka-band for a wide range of targets in order to define a set of well calibrated and reliable Ka-band backscatter coefficients for different kinds of targets. We propose several examples of backscatter data resulting from a critical survey of available datasets at Ka-band, focusing on the most interesting cases and addressing both correspondences and differences. The reliability of the results will be assessed via a preliminary comparison with ElectroMagnetic (EM) theoretical models. Furthermore, in support of future technological applications, we have designed a prototypal software acting as a "library" of earth surface radar response. In our intention, the output of the study shall contribute to answer to the need of a trustworthy Ka-Band backscatter reference. It will be of great value for future technological applications, such as support to instrument analysis, design and requirements' definition (e.g.: Signal to Noise Ratio, Noise Equivalent Sigma Zero).

  3. Ka-Band ARM Zenith Radar (KAZR) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-03-06

    The Ka-band ARM zenith radar (KAZR) is a zenith-pointing Doppler cloud radar operating at approximately 35 GHz. The KAZR is an evolutionary follow-on radar to ARM's widely successful millimeter-wavelength cloud radar (MMCR). The main purpose of the KAZR is to provide vertical profiles of clouds by measuring the first three Doppler moments: reflectivity, radial Doppler velocity, and spectra width. At the sites where the dual-polarization measurements are made, the Doppler moments for the cross-polarization channel are also available. In addition to the moments, velocity spectra are also continuously recorded for each range gate.

  4. Experimental tests of methods for the measurement of rainfall rate using an airborne dual-wavelength radar

    Science.gov (United States)

    Meneghini, R.; Nakamura, K.; Ulbrich, C. W.; Atlas, D.

    1989-01-01

    Several attenuation-based methods for estimating the rainfall rate were applied to measurements made by an airborne dual-wavelength radar operating at 0.87 cm, the K(a)-band, and at 3 cm, the X-band. These methods included the traditional Z-R methods, designated Z(X)-R and Z(K)-R for the X- and K(a) band wavelengths, respectively; single- and dual-wavelength surface reference techniques (SRT and DSRT, respectively); and standard dual-wavelength methods with and without range-averaging. As the primary sources of error for these methods are nearly independent, agreement among the rain rates obtained with these methods would lend confidence in the results. Correlation coefficients obtained between the rainfall rates with the Z(X)-R and DSRT methods were generally between 0.7 and 0.9. Good agreement among the methods occurred most often in stratiform rain for rain rates betwen a few mm/hr to about 15 mm/hr, i.e., where attenuation at the shorter wavelength is significant but not so severe as to result in a loss of signal.

  5. Dual Ka-band radar field campaign for GPM/DPR algorithm development

    Science.gov (United States)

    Nakagawa, K.; Nishikawa, M.; Nakamura, K.; Komachi, K.; Hanado, H.; Kawamura, S.; Sugitani, S.; Minda, H.; Shimizu, S.; Oki, R.

    2012-04-01

    The Global Precipitation Measurement (GPM) mission is an expanded follow-on mission to TRMM (Tropical Rainfall Measuring Mission) and a GPM core satellite will carry dual frequency precipitation radar (DPR) and a GPM Microwave Imager on board. The DPR, which is being developed by National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA), consists of two radars; Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The DPR is expected to advance precipitation science by expanding the coverage of observations to higher latitudes than those of the TRMM/PR, measuring snow and light rain by the KaPR, and providing drop size distribution information based on the differential attenuation of echoes at two frequencies. In order to secure the quality of precipitation estimates, ground validation (GV) of satellite data and retrieval algorithms is essential. Since end-to-end comparisons between instantaneous precipitation data observed by satellite and ground-based instruments is not enough to improve the algorithms. The error of various physical parameters in the precipitation retrieval algorithms (e.g. attenuation factor, drop size distribution, terminal velocity, density of the snow particles, etc.) will be estimated by the comparison with the ground-based observation data. A dual Ka-band radar system is developed by the JAXA for the GPM/DPR algorithm development. The dual Ka-radar system which consists of two identical Ka-band radars can measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those parameters are important particularly for snow measurement. Using the dual Ka-radar system along with other instruments, such as a polarimetric precipitation radar, a wind-profiler radar, ground-based precipitation measurement systems, the uncertainties of the parameters in the DPR algorithm can be reduced. The verification of improvement of rain retrieval with the DPR algorithm is

  6. A new low-cost 10 ns pulsed Ka-band radar

    Science.gov (United States)

    Eskelinen, Pekka; Ylinen, Juhana

    2011-07-01

    Two Gunn oscillators, conventional intermediate frequency building blocks, and a modified GaAs diode detector are combined to form a portable monostatic 10 ns instrumentation radar for outdoor Ka-band radar cross section measurements. At 37.8 GHz the radar gives +20 dBm output power and its tangential sensitivity is -76 dBm. Processing bandwidth is 125 MHz, which also allows for some frequency drift in the Gunn devices. Intra-pulse frequency chirp is less than 15 MHz. All functions are steered by a microcontroller. First measurements convince that the construction has a reasonable ability to reduce close-to-ground surface clutter and gives an effective way of resolving target detail. This is beneficial especially when amplitude fluctuations disturb measurements with longer pulses. The new unit operates on 12 V dc, draws a current of less than 3 A, and weighs 5 kg.

  7. Sea surface Ka-band radar cross-section from field observations in the Black Sea

    Science.gov (United States)

    Yurovsky, Yury; Kudryavtsev, Vladimir; Grodsky, Semyon; Chapron, Bertrand

    2016-04-01

    An interest in Ka-band radar backscattering from the ocean surface is growing due to better spatial resolution and more accurate Doppler anomaly estimate. But, available empirical models of Ka-band cross-section are quite scarce and sometime controversial. Here we present multi-year (2009-2015) field measurements of Ka-band co-polarized (VV and HH) sea surface normalized radar cross-section (NRCS) from research platform in the Black sea collected in a wide range of observation and sea state conditions. The data are fitted by polynomial function of incidence angle, azimuth and wind speed with accounting for measured radar antenna pattern. This empirical NRCS is compared with published Ka- and Ku-band data. Our Ka-band NRCS is close to Ku-band, but is 5-7 dB higher than 'pioneer' measurements by Masuko et al. (1986). Following the two-scale Bragg paradigm, the NRCS is split into polarized (Bragg) and non-polarized components and analyzed in terms of polarization ratio (VV/HH) and polarization difference (VV-HH) to estimate wave spectra at the Bragg wave number. Non-polarized component dominates at low incidence angles 60°) NRCS azimuth dependency is unimodal (upwind peak) for HH and bimodal (with up- and downwind peaks) for VV polarization. This again can be attributed to different backscattering mechanisms for VV and HH polarizations. With decreasing of incidence angle, up- to downwind ratio tends to 1, and under light wind conditions (4-6 m/s) can be less than 1. The same situation is observed for polarization difference, which reflects Bragg backscattering properties only. This effect can be explained by enhanced roughness on upwind (windward) face of the tilting wave. Retrieval of Bragg roughness properties shows that omni-directional saturation spectra at ~1000 rad/m are 2-3 times higher (0.01 at 10 m/s wind speed) than the spectra obtained from optical measurements of regular sea surface without wave breaking. This suggests that observed difference can arise

  8. Automated rain rate estimates using the Ka-band ARM Zenith Radar (KAZR

    Directory of Open Access Journals (Sweden)

    A. Chandra

    2014-02-01

    Full Text Available The use of millimeter wavelength radars for probing precipitation has recently gained interest. However, estimation of precipitation variables is not straightforward due to strong attenuation, radar receiver saturation, antenna wet radome effects and natural microphysical variability. Here, an automated algorithm is developed for routinely retrieving rain rates from profiling Ka-band (35-GHz ARM zenith radars (KAZR. A 1-D simple, steady state microphysical model is used to estimate the impact of microphysical processes and attenuation on the profiles of the radar observables at 35-GHz and thus provide criteria for identifying when attenuation or microphysical processes dominate KAZR observations. KAZR observations are also screened for saturation and wet radome effects. The proposed algorithm is implemented in two steps: high rain rates are retrieved by using the amount of attenuation in rain layers, while lower rain rates by the Ze–R (reflectivity-rain rate relation is implemented. Observations collected by the KAZR, disdrometer and scanning weather radars during the DYNAMO/AMIE field campaign at Gan Island of the tropical Indian Ocean are used to validate the proposed approach. The results indicate that the proposed algorithm can be used to derive robust statistics of rain rates in the tropics from KAZR observations.

  9. Automated rain rate estimates using the Ka-band ARM zenith radar (KAZR)

    Science.gov (United States)

    Chandra, A.; Zhang, C.; Kollias, P.; Matrosov, S.; Szyrmer, W.

    2015-09-01

    The use of millimeter wavelength radars for probing precipitation has recently gained interest. However, estimation of precipitation variables is not straightforward due to strong signal attenuation, radar receiver saturation, antenna wet radome effects and natural microphysical variability. Here, an automated algorithm is developed for routinely retrieving rain rates from the profiling Ka-band (35-GHz) ARM (Atmospheric Radiation Measurement) zenith radars (KAZR). A 1-dimensional, simple, steady state microphysical model is used to estimate impacts of microphysical processes and attenuation on the profiles of radar observables at 35-GHz and thus provide criteria for identifying situations when attenuation or microphysical processes dominate KAZR observations. KAZR observations are also screened for signal saturation and wet radome effects. The algorithm is implemented in two steps: high rain rates are retrieved by using the amount of attenuation in rain layers, while low rain rates are retrieved from the reflectivity-rain rate (Ze-R) relation. Observations collected by the KAZR, rain gauge, disdrometer and scanning precipitating radars during the DYNAMO/AMIE field campaign at the Gan Island of the tropical Indian Ocean are used to validate the proposed approach. The differences in the rain accumulation from the proposed algorithm are quantified. The results indicate that the proposed algorithm has a potential for deriving continuous rain rate statistics in the tropics.

  10. Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

    Science.gov (United States)

    Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

    2011-01-01

    An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

  11. First Airswot Ka-Band Radar Backscatter Returns over a Complex California Wetland

    Science.gov (United States)

    Baney, O. N.; Smith, L. C.; Pitcher, L. H.; Gleason, C. J.; Chu, V. W.; Bennett, M. M.; Pavelsky, T.; Sadowy, G. A.

    2014-12-01

    In anticipation of the launch of the NASA Surface Water Ocean Topography (SWOT) mission, this project was conducted around the Piute Ponds of Edwards Air Force Base within the Mojave Desert, California to characterize ground conditions simultaneously with two AirSWOT flights collected May 14th, 2014. Both SWOT and AirSWOT employ a Ka-band interferometer to map water surface elevations and extent, but the ability of Ka-band radar to discriminate shorelines and flooded vegetation is not well known. Presumed bright returns from moist soils surrounding surface water bodies have also been speculated to confound interpretation of SWOT/AirSWOT data. The Piute Ponds are a dynamic area of constantly changing water conditions, providing a convenient test site for field studies to assess open water, dry shorelines, vegetation edges, islands, flooded vegetation and soil moisture in conjunction with AirSWOT backscatter and visible/near-infrared camera imagery. Islands were characterized into dry islands and flooded vegetation stands including species such as bulrush (Scripus acutus) and tamarisk (Tammarix ramosissima). Results demonstrate that full water extent can be determined by near-range backscatter returns which are strong for both open water and flooded vegetation. Far-range backscatter returns over open water were unreliable for flooded extent. Comparing near-range and far-range backscatter results to the soil moisture transect shows correlation, however as soil moisture increases, discriminating between wet sediment and water becomes difficult. In sum, first results suggest near-return backscatter results prove most useful in distinguishing open water from non-water, with a strong correlation between soil moisture and backscatter returns.

  12. A Study of Air/Space-borne Dual-Wavelength Radar for Estimation of Rain Profiles

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In this study, a framework is given by which air/space-borne dual-wavelength radar data can be used to estimate the characteristic parameters of hydrometeors. The focus of the study is on the Global Precipitation Measurement (GPM) precipitation radar, a dual-wavelength radar that will operate in the Ku (13.6 GHz) and Ka (35 GHz) bands. A key aspect of the retrievals is the relationship between the differential frequency ratio (DFR) and the median volume diameter, Do, and its dependence on the phase state of the hydrometeors. It is shown that parametric plots of Do and particle concentration in the plane of the DFR and the radar reflectivity factor in the Ku band can be used to reduce the ambiguities in deriving Do from DFR. A self-consistent iterative algorithm, which does not require the use of an independent pathattenuation constraint, is examined by applying it to the apparent radar reflectivity profiles simulated from a drop size distribution (DSD) model. For light to moderate rain, the self-consistent rain profiling approach converges to the correct solution only if the same shape factor of the Gamma distributions is used both to generate and retrieve the rain profiles. On the other hand, if the shape factors differ, the iteration generally converges but not to the correct solution. To further examine the dual-wavelength techniques, the selfconsistent iterative algorithm, along with forward and backward rain profiling algorithms, are applied to measurements taken from the 2nd generation Precipitation Radar (PR-2) built by the Jet Propulsion Laboratory. Consistent with the model results, it is found that the estimated rain profiles are sensitive to the shape factor of the size distribution when the iterative, self-consistent approach is used but relatively insensitive to this parameter when the forward- and backward-constrained approaches are used.

  13. Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

    Science.gov (United States)

    Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  14. Current status of Dual Ka-band radar field campaign in Japan for GPM/DPR mission

    Science.gov (United States)

    Kaneko, Yuki; Nakagawa, Katsuhiro; Nishikawa, Masanori; Nakamura, Kenji; Fujiyoshi, Yasushi; Hanado, Hiroshi; Minda, Haruya; Yamamoto, Kazuhide; Oki, Riko; Furukawa, Kinji

    2013-04-01

    The Global Precipitation Measurement (GPM) mission is an expanded follow-on mission to TRMM (Tropical Rainfall Measuring Mission) and a GPM core satellite will carry dual frequency precipitation radar (DPR) and a GPM Microwave Imager on board. The DPR, which is being developed by National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA), consists of two radars; Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The DPR is expected to advance precipitation science by expanding the coverage of observations to higher latitudes than those of the TRMM/PR, measuring snow and light rain by the KaPR, and providing drop size distribution information based on the differential attenuation of echoes at two frequencies. In order to secure the quality of precipitation estimates, ground validation (GV) of satellite data and retrieval algorithms is essential. Since end-to-end comparisons between instantaneous precipitation data observed by satellite and ground-based instruments is not enough to improve the algorithms. The error of various physical parameters in the precipitation retrieval algorithms (e.g. attenuation factor, drop size distribution, terminal velocity, density of the snow particles, etc.) will be estimated by the comparison with the ground-based observation data. A dual Ka-band radar system is developed by the JAXA for the GPM/DPR algorithm development. The dual Ka-radar system which consists of two identical Ka-band radars can measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those parameters are important particularly for snow measurement. Using the dual Ka-radar system along with other instruments, such as a polarimetric precipitation radar, a wind-profiler radar, ground-based precipitation measurement systems, the uncertainties of the parameters in the DPR algorithm can be reduced. The verification of improvement of rain retrieval with the DPR algorithm is

  15. Performance Analysis of Ultra-Wideband Channel for Short-Range Monopulse Radar at Ka-Band

    Directory of Open Access Journals (Sweden)

    Naohiko Iwakiri

    2012-01-01

    Full Text Available High-range resolution is inherently provided with Ka-band ultra-wideband (UWB vehicular radars. The authors have developed a prototype UWB monopulse radar equipped with a two-element receiving antenna array and reported its measurement results. In this paper, a more detailed verification using these measurements is presented. The measurements were analyzed employing matched filtering and eigendecomposition, and then multipath components were extracted to examine the behavior of received UWB monopulse signals. Next, conventional direction finding algorithms based on narrowband assumption were evaluated using the extracted multipath components, resulting in acceptable angle-of-arrival (AOA from the UWB monopulse signal regardless of wideband signals. Performance degradation due to a number of averaging the received monopulses was also examined to design suitable radar's waveforms.

  16. Retrieve Optically Thick Ice Cloud Microphysical Properties by Using Airborne Dual-Wavelength Radar Measurements

    Science.gov (United States)

    Wang, Zhien; Heymsfield, Gerald M.; Li, Lihua; Heymsfield, Andrew J.

    2005-01-01

    An algorithm to retrieve optically thick ice cloud microphysical property profiles is developed by using the GSFC 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) measurements aboard the high-altitude ER-2 aircraft. In situ size distribution and total water content data from the CRYSTAL-FACE field campaign are used for the algorithm development. To reduce uncertainty in calculated radar reflectivity factors (Ze) at these wavelengths, coincident radar measurements and size distribution data are used to guide the selection of mass-length relationships and to deal with the density and non-spherical effects of ice crystals on the Ze calculations. The algorithm is able to retrieve microphysical property profiles of optically thick ice clouds, such as, deep convective and anvil clouds, which are very challenging for single frequency radar and lidar. Examples of retrieved microphysical properties for a deep convective clouds are presented, which show that EDOP and CRS measurements provide rich information to study cloud structure and evolution. Good agreement between IWPs derived from an independent submillimeter-wave radiometer, CoSSIR, and dual-wavelength radar measurements indicates accuracy of the IWC retrieved from the two-frequency radar algorithm.

  17. A Novel Low-Cost Dual-Wavelength Precipitation Radar Sensor Network Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Remote Sensing Solutions, Inc. (RSS) has developed a novel, practical design that will produce a low-cost precipitation radar / radiometer sensor. Operating in a...

  18. Ku/Ka-band electrically-scanned line array for tri-band cloud and precipitation radar applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A spaceborne radar system that operates simultaneously at multiple frequency bands from microwave through millimeter-wave frequencies can exploit the largely varying...

  19. Volcanic Ash Cloud Observation using Ground-based Ka-band Radar and Near-Infrared Lidar Ceilometer during the Eyjafjallajökull eruption

    Directory of Open Access Journals (Sweden)

    Frank S. Marzano

    2015-03-01

    Full Text Available Active remote sensing techniques can probe volcanic ash plumes, but their sensitivity at a given distance depends upon the sensor transmitted power, wavelength and polarization capability. Building on a previous numerical study at centimeter wavelength, this work aims at i simulating the distal ash particles polarimetric response of millimeter-wave radar and multi-wavelength optical lidar; ii developing and applying a model-based statistical retrieval scheme using a multi-sensor approach. The microphysical electromagnetic forward model of volcanic ash particle distribution, previously set up at microwaves, is extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena for both millimeter and optical bands. Monte Carlo generation of radar and lidar signatures are driven by random variability of volcanic particle main parameters, using constraints from available data and experimental evidences. The considered case study is related to the ground-based observation of the Eyjafjallajökull (Iceland volcanic ash plume on May 15, 2010, carried out by the Atmospheric Research Station at Mace Head (Ireland with a 35-GHz Ka-band Doppler cloud radar and a 1064-nm ceilometer lidar. The detection and estimation of ash layer presence and composition is carried out using a Bayesian approach, which is trained by the Monte Carlo model-based dataset. Retrieval results are corroborated exploiting auxiliary data such as those from a ground-based microwave radiometer also positioned at Mace Head.

  20. Dual-wavelength millimeter-wave radar measurements of cirrus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Sekelsky, S.M.; Firda, J.M.; McIntosh, R.E. [Univ. of Massachusetts, Amherst, MA (United States)

    1996-04-01

    In April 1994, the University of Massachusetts` 33-GHz/95-GHz Cloud Profiling Radar System (CPRS) participated in the multi-sensor Remote Cloud Sensing (RCS) Intensive Operation Period (IOP), which was conducted at the Southern Great Plains Cloud and Radiation Testbed (CART). During the 3-week experiment, CPRS measured a variety of cloud types and severe weather. In the context of global warming, the most significant measurements are dual-frequency observations of cirrus clouds, which may eventually be used to estimate ice crystal size and shape. Much of the cirrus data collected with CPRS show differences between 33-GHz and 95-GHz reflectivity measurements that are correlated with Doppler estimates of fall velocity. Because of the small range of reflectivity differences, a precise calibration of the radar is required and differential attenuation must also be removed from the data. Depolarization, which is an indicator of crystal shape, was also observed in several clouds. In this abstract we present examples of Mie scattering from cirrus and estimates of differential attenuation due to water vapor and oxygen that were derived from CART radiosonde measurements.

  1. Retrieval of Raindrop Size Distribution, Vertical Air Velocity and Water Vapor Attenuation Using Dual-Wavelength Doppler Radar Observations

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; Srivastava, C.

    2005-01-01

    Two techniques for retrieving the slope and intercept parameters of an assumed exponential raindrop size distribution (RSD), vertical air velocity, and attenuation by precipitation and water vapor in light stratiform rain using observations by airborne, nadir looking dual-wavelength (X-band, 3.2 cm and W-band, 3.2 mm) radars are presented. In both techniques, the slope parameter of the RSD and the vertical air velocity are retrieved using only the mean Doppler velocities at the two wavelengths. In the first method, the intercept of the RSD is estimated from the observed reflectivity at the longer wavelength assuming no attenuation at that wavelength. The attenuation of the shorter wavelength radiation by precipitation and water vapor are retrieved using the observed reflectivity at the shorter wavelength. In the second technique, it is assumed that the longer wavelength suffers attenuation only in the melting band. Then, assuming a distribution of water vapor, the melting band attenuation at both wavelengths and the rain attenuation at the shorter wavelength are retrieved. Results of the retrievals are discussed and several physically meaningful results are presented.

  2. KARIN: The Ka-Band Radar Interferometer for the Proposed Surface Water and Ocean Topography (SWOT) Mission

    Science.gov (United States)

    Esteban-Fernandez, Daniel; Peral, Eva; McWatters, Dalia; Pollard, Brian; Rodriguez, Ernesto; Hughes, Richard

    2013-01-01

    Over the last two decades, several nadir profiling radar altimeters have provided our first global look at the ocean basin-scale circulation and the ocean mesoscale at wavelengths longer than 100 km. Due to sampling limitations, nadir altimetry is unable to resolve the small wavelength ocean mesoscale and sub-mesoscale that are responsible for the vertical mixing of ocean heat and gases and the dissipation of kinetic energy from large to small scales. The proposed Surface Water and Ocean Topography (SWOT) mission would be a partnership between NASA, CNES (Centre National d'Etudes Spaciales) and the Canadian Space Agency, and would have as one of its main goals the measurement of ocean topography with kilometer-scale spatial resolution and centimeter scale accuracy. In this paper, we provide an overview of all ocean error sources that would contribute to the SWOT mission.

  3. Modulation transfer functions at Ka band

    Science.gov (United States)

    Hesany, Vahid; Sistani, Bita; Salam, Asif; Haimov, Samuel; Gogineni, Prasad; Moore, Richard K.

    The modulation transfer function (MTF) is often used to describe the modulation of the radar signal by the long waves. MTFs were measured at 35 GHz (Ka band) with a switched-beam vector slope gauge/scatterometer on the research platform NORDSEE as part of the SAXON-FPN experiment. Three independent measurements of the scattering were available for each height measurement. This provided the opportunity to average the time series to reduce the effects of fading noise and sea spikes, or, alternatively, to append the time series to achieve more degrees of freedom in the spectral estimates. For upwind measurements, the phase of the VV-polarized Ka-band MTF was always positive, which implies that the maximum of the radar return originates from the forward face of the long-scale waves. This phase increases with increasing wind speed. The magnitude of the MTF decreases with increasing wind speed.

  4. Analysis of Dual-Frequency Ocean Backscatter Measurements at Ku- and Ka-Bands Using Near-Nadir Incidence GPM Radar Data

    OpenAIRE

    NOUGUIER, Frederic; Mouche, Alexis; Rascle, Nicolas; Chapron, Bertrand; Vandemark, Douglas

    2016-01-01

    Global colocalized ocean surface measurements using the Global Precipitation Measurement near-nadir dual-frequency Ku- and Ka-band microwave measurements are analyzed and compared. Focusing on the Ka and Ku cross-sections fall-off with incidence angles, the contemporaneous measurements enable to more precisely document differing ocean scattering characteristics for both microwave frequencies. Sensitivity with wind speed and significant wave height is further reported using global comparisons ...

  5. Airborne Field Campaign Results of Ka-band Precipitation Measuring Radar in China%我国Ka频段降水测量雷达机载校飞试验结果

    Institute of Scientific and Technical Information of China (English)

    商建; 郭杨; 吴琼; 杨虎; 尹红刚

    2011-01-01

    2010年6-10月在天津与江苏地区开展了国内首次Ku/Ka频段星载降水测量雷达机载校飞试验.此次校飞试验获得了宝贵的机载雷达观测数据和地面、海面同步观测数据,目前已开展了外定标、数据对比与衰减订正等工作.该文给出了天津校飞试验中Ka频段降水测量雷达实测结果,对Ka频段降水测量雷达资料与天津地区S波段地基多普勒雷达资料进行了详细的对比分析,有利于更好地了解Ka频段降水测量雷达仪器本身的性能及其探测降水的能力;利用由GPS探空资料、地基多通道微波辐射计观测亮温结合微波辐射传输模式得到的雷达路径积分衰减量,对Ka频段降水测量雷达进行了衰减订正,为继续开展降水反演工作奠定了基础.%Spaceborne precipitation measuring radar can measure precipitation quantitatively, observe the vertical distribution and provide three dimensional precipitation structures. Spaceborne precipitation measuring radar is an important instrument on FY-3 meteorological satellite constellation. As a possible future member of the Global Precipitation Measurement(GPM) , this satellite will carry dual-frequency precipitation radar operating at Ku and Ka bands to provide scientific data for dual-frequency retrieval algorithm. Its two prototype devices, Ku-band and Ka-band radars have already been developed under the support of National Defense Science and Industry Bureau. Field campaign of Ku/Ka-band airborne precipitation measuring radar is carried out by National Satellite Meteorological Center of China Meteorological Administration combining several groups from June to October in 2010 in Tianjin and Jiangsu, called BH-RM 2010 and JS-RM 2010, respectively. This is the first time that China carries out airborne precipitation measuring radar field campaign. The purposes of this field campaign are to validate the correctness of internal and external calibration scheme under airborne

  6. Validation of GPM Ka-Radar Algorithm Using a Ground-based Ka-Radar System

    Science.gov (United States)

    Nakamura, Kenji; Kaneko, Yuki; Nakagawa, Katsuhiro; Furukawa, Kinji; Suzuki, Kenji

    2016-04-01

    GPM led by the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration of US (NASA) aims to observe global precipitation. The core satellite is equipped with a microwave radiometer (GMI) and a dual-frequency radar (DPR) which is the first spaceborne Ku/Ka-band dual-wavelength radar dedicated for precipitation measurement. In the DPR algorithm, measured radar reflectivity is converted to effective radar reflectivity by estimating the rain attenuation. Here, the scattering/attenuation characteristics of Ka-band radiowaves are crucial, particularly for wet snow. A melting layer observation using a dual Ka-band radar system developed by JAXA was conducted along the slope of Mt. Zao in Yamagata Prefecture, Japan. The dual Ka-band radar system consists of two nearly identical Ka-band FM-CW radars, and the precipitation systems between two radars were observed in opposite directions. From this experiment, equivalent radar reflectivity (Ze) and specific attenuation (k) were obtained. The experiments were conducted for two winter seasons. During the data analyses, it was found that k estimate easily fluctuates because the estimate is based on double difference calculation. With much temporal and spatial averaging, k-Ze relationship was obtained for melting layers. One of the results is that the height of the peak of k seems slightly higher than that of Ze. The results are compared with in-situ precipitation particle measurements.

  7. Fade Mitigation Techniques at Ka-Band

    Science.gov (United States)

    Dissanayake, Asoka (Editor)

    1996-01-01

    Rain fading is the dominant propagation impairment affecting Ka-band satellite links and rain fade mitigation is a key element in the design of Ka-band satellite networks. Some of the common fade mitigation techniques include: power control, diversity, adaptive coding, and resource sharing. The Advanced Communications Technology Satellite (ACTS) provides an excellent opportunity to develop and test Ka-band rain impairment amelioration techniques. Up-link power control and diversity are discussed in this paper.

  8. Solid State KA-Band, Solid State W-Band and TWT Amplifiers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phase I of the proposal describes plans to develop a state of the art transmitter for the W-Band and KA -Band Cloud Radar system. Our focus will be concentrated in...

  9. Ka-band waveguide rotary joint

    KAUST Repository

    Yevdokymov, Anatoliy

    2013-04-11

    The authors present a design of a waveguide rotary joint operating in Ka-band with central frequency of 33 GHz, which also acts as an antenna mount. The main unit consists of two flanges with a clearance between them; one of the flanges has three circular choke grooves. Utilisation of three choke grooves allows larger operating clearance. Two prototypes of the rotary joint have been manufactured and experimentally studied. The observed loss is from 0.4 to 0.8 dB in 1.5 GHz band.

  10. High Efficiency Ka-Band Spatial Combiner

    Directory of Open Access Journals (Sweden)

    D. Passi

    2014-12-01

    Full Text Available A Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC is proposed in this paper, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS transitions. At the date of this paper and at the Author's best knowledge no such FLuS innovative transitions have been reported in literature before. These transitions are inserted into a WR28 waveguide T-junction, in order to allow the integration of 16 Monolithic Microwave Integrated Circuit (MMIC Solid State Power Amplifiers (SSPA's. A computational electromagnetic model using the finite elements method has been implemented. A mean insertion loss of 2 dB is achieved with a return loss better the 10 dB in the 31-37 GHz bandwidth.

  11. Aeronautical applications of steerable K/Ka-band antennas

    Science.gov (United States)

    Helmken, Henry; Prather, Horton

    1995-01-01

    The expected growth of wideband data and video transmission via satellite will press existing satellite Ku-band services and push development of the Ka-band region. Isolated ground based K/Ka-band terminals can experience severe fading due to rain and weather phenomena. However, since aircraft generally fly above the severe weather, they are attractive platforms for developing commercial K/Ka-band communication links.

  12. High power Ka band TWT amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Golkowski, C.; Ivers, J.D.; Nation, J.A.; Wang, P.; Schachter, L.

    1999-07-01

    Two high power 35 GHz TWT amplifiers driven by a relativistic pencil, 850 kV, 200A electron beam have been assembled and tested. The first had a dielectric slow wave structure and was primarily used to develop diagnostics, and to gain experience in working with high power systems in Ka band. The source of the input power for the amplifier was a magnetron producing a 30 kW, 200ns long pulse of which 10 kW as delivered to the experiment. The 30 cm long dielectric (Teflon) amplifier produced output power levels of about 1 MW with a gain of about 23 dB. These results are consistent with expectations from PIC code simulations for this arrangement. The second amplifier, which is a single stage disk loaded slow wave structure, has been designed. It consists of one hundred uniform cells with two sets of ten tapered calls at the ends to lower the reflection coefficient. The phase advance per cell is {pi}/2. The amplifier passband extends from 28 to 40 GHz. It is designed to increase the output power to about 20 MW. The amplifier is in construction and will be tested in the near future. Details of the design of both systems will be provided and initial results from the new amplifier presented.

  13. A Novel Low-cost, Ka-band, High Altitude, Multi-Baseline Unmanned Aerial Vehicle Sensor for Surface Water Ocean Topography Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal presents the Ka-band SWOT Phenomenology Airborne Radar (KaSPAR) to support the surface water ocean topography (SWOT) mission for science and algorithm...

  14. Dichroic Filter for Separating W-Band and Ka-Band

    Science.gov (United States)

    Epp, Larry W.; Durden, Stephen L.; Jamnejad, Vahraz; Long, Ezra M.; Sosnowski, John B.; Higuera, Raymond J.; Chen, Jacqueline C.

    2012-01-01

    The proposed Aerosol/Cloud/Ecosystems (ACEs) mission development would advance cloud profiling radar from that used in CloudSat by adding a 35-GHz (Ka-band) channel to the 94-GHz (W-band) channel used in CloudSat. In order to illuminate a single antenna, and use CloudSat-like quasi-optical transmission lines, a spatial diplexer is needed to add the Ka-band channel. A dichroic filter separates Ka-band from W-band by employing advances in electrical discharge machining (EDM) and mode-matching analysis techniques developed and validated for designing dichroics for the Deep Space Network (DSN), to develop a preliminary design that both met the requirements of frequency separation and mechanical strength. First, a mechanical prototype was built using an approximately 102-micron-diameter EDM process, and tolerances of the hole dimensions, wall thickness, radius, and dichroic filter thickness measured. The prototype validated the manufacturing needed to design a dichroic filter for a higher-frequency usage than previously used in the DSN. The initial design was based on a Ka-band design, but thicker walls are required for mechanical rigidity than one obtains by simply scaling the Ka-band dichroic filter. The resulting trade of hole dimensions for mechanical rigidity (wall thickness) required electrical redesign of the hole dimensions. Updates to existing codes in the linear solver decreased the analysis time using mode-matching, enabling the electrical design to be realized quickly. This work is applicable to missions and instruments that seek to extend W-band cloud profiling measurements to other frequencies. By demonstrating a dichroic filter that passes W-band, but reflects a lower frequency, this opens up the development of instruments that both compare to and enhance CloudSat.

  15. Ka-Band MMIC T/R Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is specifically written to address the need for improved Ka-band T/R modules. The solicitation calls for investigation and development of core...

  16. Ka-Band MMIC T/R Module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase II proposal is presented as the follow on to the Phase I SBIR contract number NNC06CB21C entitled "Ka-band MMIC T/R Module" For active microwave...

  17. Ka-band InSAR Imaging and Analysis Based on IMU Data

    Directory of Open Access Journals (Sweden)

    Shi Jun

    2014-02-01

    Full Text Available Compared with other bands, the millimeter wave Interferometric Synthetic Aperture Radar (InSAR has high accuracy and small size, which is a hot topic in InSAR research. On the other hand, shorter wavelength causes difficulties in 2D imaging and interferometric phase extraction. In this study, the imaging and phase performance of the streaming Back Projection (BP method combined with IMU data are analyzed and discussed on the basis of actual Ka-band InSAR data. It is found that because the wavelength of the Ka-band is short, it is more sensitive to the antenna phase-center history. To ensure the phase-preserving capacity, the IMU data must be used with accurate motion error compensation. Furthermore, during data processing, we verify the flat-earth-removing capacity of the BP algorithm that calculates and compensates the master and slave antenna phase centers individually.

  18. A Ka-Band Backscatter Model Function and an Algorithm for Measurement of the Wind Vector Over the Sea Surface

    NARCIS (Netherlands)

    Nekrasov, A.; Hoogeboom, P.

    2005-01-01

    A Ka-band backscatter model and an algorithm for measurement of the wind speed and direction over the sea surface by a frequency-modulated continous-wave radar demonstrator system operated in scatterometer mode have been developed. To evaluate the proposed algorithm, a simulation of the wind vector

  19. Ka-band MMIC microstrip array for high rate communications

    Science.gov (United States)

    Lee, R. Q.; Raquet, C. A.; Tolleson, J. B.; Sanzgiri, S. M.

    1991-01-01

    In a recent technology assessment of alternative communication systems for the space exploration initiative (SEI), Ka-band (18 to 40 GHz) communication technology was identified to meet the mission requirements of telecommunication, navigation, and information management. Compared to the lower frequency bands, Ka-band antennas offer higher gain and broader bandwidths; thus, they are more suitable for high data rate communications. Over the years, NASA has played an important role in monolithic microwave integrated circuit (MMIC) phased array technology development, and currently, has an ongoing contract with Texas Instrument (TI) to develop a modular Ka-band MMIC microstrip subarray (NAS3-25718). The TI contract emphasizes MMIC integration technology development and stipulates using existing MMIC devices to minimize the array development cost. The objective of this paper is to present array component technologies and integration techniques used to construct the subarray modules.

  20. X-/Ka-band dichroic plate noise temperature reduction

    Science.gov (United States)

    Veruttipong, W.; Lee, P.

    1994-11-01

    The X-/Ka-band (8.4 GHz/32.0 GHz) dichroic plate installed as DSS 13 contributes an estimated 3 K to the system noise temperature at 32.0 GHz. Approximately 1 percent of the Ka-band incident field is reflected by the plate into the 300-K environment of the DSS-13 pedestal room. A low-cost, easily implemented method of reducing the noise temperature is presented. Using a curved reflector, the reflected field can be re-focused into an 80-K cold load, reducing the noise temperature contribution of the dichroic plate by about 2 K.

  1. Additive manufacturing of Ka-band antennas for wireless communications

    DEFF Research Database (Denmark)

    Armendariz, Unai; Rommel, Simon; Rodríguez Páez, Juan Sebastián

    2016-01-01

    This paper presents the design and fabrication of WR-28 waveguide horn antennas operating in the Ka-band frequency range between 26.5 GHz and 40 GHz through 3D printing. Three different antennas are fabricated from polylactide acid filaments in conductive and non-conductive variants; the latter...

  2. Experimental radio frequency link for Ka-band communications applications

    Science.gov (United States)

    Fujikawa, Gene; Conray, Martin J.; Saunders, Alan L.; Pope, Dale E.

    1988-01-01

    An experimental radio frequency link has been demonstrated to provide two-way communication between a remote user ground terminal and a ground-based Ka-band transponder. Bit-error-rate performance and radio frequency characteristics of the communication link were investigated.

  3. Rain Fade Compensation Alternatives for Ka Band Communication Satellites

    Science.gov (United States)

    Acosta, Roberto J.

    1997-01-01

    Future satellite communications systems operating in Ka-band frequency band are subject to degradation produced by the troposphere which is much more severe than those found at lower frequency bands. These impairments include signal absorption by rain, clouds and gases, and amplitude scintillation's arising from refractive index irregularities. For example, rain attenuation at 20 GHz is almost three times that at 11 GHz. Although some of these impairments can be overcome by oversizing the ground station antennas and high power amplifiers, the current trend is using small (less than 20 inches apertures), low-cost ground stations (less than $1000) that can be easily deployed at user premises. As a consequence, most Ka-band systems are expected to employ different forms of fade mitigation that can be implemented relatively easily and at modest cost. The rain fade mitigation approaches are defined by three types of Ka-band communications systems - a low service rate (less than 1.5 Mb/s), a moderate service rate (1.5 to 6 Mb/s) system and a high service rate (greater than 43 Mb/s) system. The ACTS VSAT network, which includes an adaptive rain fade technique, is an example of a moderate service rate.

  4. Mars Global Surveyor Ka-Band Frequency Data Analysis

    Science.gov (United States)

    Morabito, D.; Butman, S.; Shambayati, S.

    2000-01-01

    The Mars Global Surveyor (MGS) spacecraft, launched on November 7, 1996, carries an experimental space-to-ground telecommunications link at Ka-band (32 GHz) along with the primary X-band (8.4 GHz) downlink. The signals are simultaneously transmitted from a 1.5-in diameter parabolic high gain antenna (HGA) on MGS and received by a beam-waveguide (BWG) R&D 34-meter antenna located in NASA's Goldstone Deep Space Network (DSN) complex near Barstow, California. The projected 5-dB link advantage of Ka-band relative to X-band was confirmed in previous reports using measurements of MGS signal strength data acquired during the first two years of the link experiment from December 1996 to December 1998. Analysis of X-band and Ka-band frequency data and difference frequency (fx-fka)/3.8 data will be presented here. On board the spacecraft, a low-power sample of the X-band downlink from the transponder is upconverted to 32 GHz, the Ka-band frequency, amplified to I-W using a Solid State Power Amplifier, and radiated from the dual X/Ka HGA. The X-band signal is amplified by one of two 25 W TWTAs. An upconverter first downconverts the 8.42 GHz X-band signal to 8 GHz and then multiplies using a X4 multiplier producing the 32 GHz Ka-band frequency. The frequency source selection is performed by an RF switch which can be commanded to select a VCO (Voltage Controlled Oscillator) or USO (Ultra-Stable Oscillator) reference. The Ka-band frequency can be either coherent with the X-band downlink reference or a hybrid combination of the USO and VCO derived frequencies. The data in this study were chosen such that the Ka-band signal is purely coherent with the X-band signal, that is the downconverter is driven by the same frequency source as the X-band downlink). The ground station used to acquire the data is DSS-13, a 34-meter BWG antenna which incorporates a series of mirrors inside beam waveguide tubes which guide the energy to a subterranean pedestal room, providing a stable environment

  5. Ka-band bistatic ground-based SAR using noise signals

    Science.gov (United States)

    Lukin, K.; Mogyla, A.; Vyplavin, P.; Palamarchuk, V.; Zemlyaniy, O.; Tarasenko, V.; Zaets, N.; Skretsanov, V.; Shubniy, A.; Glamazdin, V.; Natarov, M.; Nechayev, O.

    2008-01-01

    Currently, one of the actual problems is remote monitoring of technical state of large objects. Different methods can be used for that purpose. The most promising of them relies on application of ground based synthetic aperture radars (SAR) and differential interferometry. We have designed and tested Ground Based Noise Waveform SAR based on noise radar technology [1] and synthetic aperture antennas [2]. It enabled to build an instrument for precise all-weather monitoring of large objects in real-time. We describe main performance of ground-based interferometric SAR which uses continuous Ka-band noise waveform as a probe signal. Besides, results of laboratory trials and evaluation of its main performance are presented as well.

  6. Design of High Power Density Amplifiers: Application to Ka Band

    Science.gov (United States)

    Passi, Davide; Leggieri, Alberto; Di Paolo, Franco; Bartocci, Marco; Tafuto, Antonio

    2017-06-01

    Recent developments in the design of high-power-high-frequency amplifiers are assessed in this paper by the analysis and measurements of a high power density amplifier operating in the Ka Band. Design procedure is presented and a technical investigation is reported. The proposed device has shown over 23% of useful frequency bandwidth. It is an ensemble of 16 monolithic solid state power amplifiers that employees mixed technologies as spatial and planar combiners. Test performed have given maximum delivered power of 47.2 dBm.

  7. NASA SCaN Overview and Ka-Band Actvities

    Science.gov (United States)

    Stegeman, James D.; Midon, Marco Mario; Davarian, Faramaz; Geldzahler, Barry

    2014-01-01

    The Ka- and Broadband Communications Conference is an international forum attended by worldwide experts in the area of Ka-Band Propagation and satellite communications. Since its inception, NASA has taken the initiative of organizing and leading technical sections on RF Propagation and satellite communications, solidifying its worldwide leadership in the aforementioned areas. Consequently, participation in this conference through the contributions described below will maintain NASA leadership in Ka- and above RF Propagation as it relates to enhancing current and future satellite communication systems supporting space exploration.

  8. Rain Fade Compensation for Ka-Band Communications Satellites

    Science.gov (United States)

    Mitchell, W. Carl; Nguyen, Lan; Dissanayake, Asoka; Markey, Brian; Le, Anh

    1997-01-01

    This report provides a review and evaluation of rain fade measurement and compensation techniques for Ka-band satellite systems. This report includes a description of and cost estimates for performing three rain fade measurement and compensation experiments. The first experiment deals with rain fade measurement techniques while the second one covers the rain fade compensation techniques. The third experiment addresses a feedback flow control technique for the ABR service (for ATM-based traffic). The following conclusions were observed in this report; a sufficient system signal margin should be allocated for all carriers in a network, that is a fixed clear-sky margin should be typically in the range of 4-5 dB and should be more like 15 dB in the up link for moderate and heavy rain zones; to obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate changes resulting in a 4-5 dB increase in the dynamic part of the system margin. The experiments would assess the feasibility of the fade measurements and compensation techniques, and ABR feedback control technique.

  9. Ka-Band Transponder for Deep-Space Radio Science

    Science.gov (United States)

    Dennis, Matthew S.; Mysoor, Narayan R.; Folkner, William M.; Mendoza, Ricardo; Venkatesan, Jaikrishna

    2008-01-01

    A one-page document describes a Ka-band transponder being developed for use in deep-space radio science. The transponder receives in the Deep Space Network (DSN) uplink frequency band of 34.2 to 34.7 GHz, transmits in the 31.8- to 32.3 GHz DSN downlink band, and performs regenerative ranging on a DSN standard 4-MHz ranging tone subcarrier phase-modulated onto the uplink carrier signal. A primary consideration in this development is reduction in size, relative to other such transponders. The transponder design is all-analog, chosen to minimize not only the size but also the number of parts and the design time and, thus, the cost. The receiver features two stages of frequency down-conversion. The receiver locks onto the uplink carrier signal. The exciter signal for the transmitter is derived from the same source as that used to generate the first-stage local-oscillator signal. The ranging-tone subcarrier is down-converted along with the carrier to the second intermediate frequency, where the 4-MHz tone is demodulated from the composite signal and fed into a ranging-tone-tracking loop, which regenerates the tone. The regenerated tone is linearly phase-modulated onto the downlink carrier.

  10. Design of Ka-band antipodal finline mixer and detector

    Institute of Scientific and Technical Information of China (English)

    Yao Changfei; Xu Jinping; Chen Mo

    2009-01-01

    This paper mainly discusses the analysis and design of a finline single-ended mixer and detector. In the circuit, for the purpose of eliminating high-order resonant modes and improving transition loss, metallic via holes are implemented along the mounting edge of the substrate embedded in the split-block of the WG-finline-microstrip transition. Meanwhile, a Ka band slow-wave and bandstop filter, which represents a reactive termination, is designed for the utilization of idle frequencies and operation frequencies energy. Full-wave analysis is carried out to optimize the input matching network of the mixer and the detector circuit using lumped elements to model the nonlinear diode. The exported S-matrix of the optimized circuit is used for conversion loss and voltage sensitivity analysis.The lowest measured conversion loss is 3.52 dB at 32.2 GHz; the conversion loss is flat and less than 5.68 dB in the frequency band of 29-34 GHz. The highest measured zero-bias voltage sensitivity is 1450 mV/mW at 38.6 GHz,and the sensitivity is better than 1000 mV/mW in the frequency band of 38-40 GHz.

  11. Ka-band MMIC subarray technology program (Ka-Mist)

    Science.gov (United States)

    Pottinger, W.

    1995-09-01

    Ka-band monolithic microwave integrated circuit (MMIC) arrays have been considered as having high potential for increasing the capability of space, aircraft, and land mobile communication systems in terms of scan performance, data rate, link margin, and flexibility while offering a significant reduction in size, weight, and power consumption. Insertion of MMIC technology into antenna systems, particularly at millimeter wave frequencies using low power and low noise amplifiers in closed proximity to the radiating elements, offers a significant improvement in the array transmit efficiency, receive system noise figure, and overall array reliability. Application of active array technology also leads to the use of advanced beamforming techniques that can improve beam agility, diversity, and adaptivity to complex signal environments. The objective of this program was to demonstrate the technical feasibility of the 'tile' array packaging architecture at EHF via the insertion of 1990 MMIC technology into a functional tile array or subarray module. The means test of this objective was to demonstrate and deliver to NASA a minimum of two 4 x 4 (16 radiating element) subarray modules operating in a transmit mode at 29.6 GHz. Available (1990) MMIC technology was chosen to focus the program effort on the novel interconnect schemes and packaging requirements rather than focusing on MMIC development. Major technical achievements of this program include the successful integration of two 4 x 4 subarray modules into a single antenna array. This 32 element array demonstrates a transmit EIRP of over 300 watts yielding an effective directive power gain in excess of 55 dB at 29.63 GHz. The array has been actively used as the transmit link in airborne/terrestrial mobile communication experiments accomplished via the ACTS satellite launched in August 1993.

  12. Studying NASA's Transition to Ka-Band Communications for Low Earth Orbit

    Science.gov (United States)

    Chelmins, David; Reinhart, Richard; Mortensen, Dale; Welch, Bryan; Downey, Joseph; Evans, Mike

    2014-01-01

    As the S-band spectrum becomes crowded, future space missions will need to consider moving command and telemetry services to Ka-band. NASAs Space Communications and Navigation (SCaN) Testbed provides a software-defined radio (SDR) platform that is capable of supporting investigation of this service transition. The testbed contains two S-band SDRs and one Ka-band SDR. Over the past year, SCaN Testbed has demonstrated Ka-band communications capabilities with NASAs Tracking and Data Relay Satellite System (TDRSS) using both open- and closed-loop antenna tracking profiles. A number of technical areas need to be addressed for successful transition to Ka-band. The smaller antenna beamwidth at Ka-band increases the criticality of antenna pointing, necessitating closed loop tracking algorithms and new techniques for received power estimation. Additionally, the antenna pointing routines require enhanced knowledge of spacecraft position and attitude for initial acquisition, versus an S-band antenna. Ka-band provides a number of technical advantages for bulk data transfer. Unlike at S-band, a larger bandwidth may be available for space missions, allowing increased data rates. The potential for high rate data transfer can also be extended for direct-to-ground links through use of variable or adaptive coding and modulation. Specific examples of Ka-band research from SCaN Testbeds first year of operation will be cited, such as communications link performance with TDRSS, and the effects of truss flexure on antenna pointing.

  13. A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.

    2015-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

  14. A Ka-band (32 GHz) beacon link experiment (KABLE) with Mars Observer

    Science.gov (United States)

    Riley, A. L.; Hansen, D. M.; Mileant, A.; Hartop, R. W.

    1987-02-01

    A proposal for a Ka-Band (32 GHz) Link Experiment (KABLE) with the Mars Observer mission was submitted to NASA. The experiment will rely on the fourth harmonic of the spacecraft X-band transmitter to generate a 33.6 GHz signal. The experiment will rely also on the Deep Space Network (DSN) receiving station equipped to simultaneously receive X- and Ka-band signals. The experiment will accurately measure the spacecraft-to-Earth telecommunication link performance at Ka-band and X-band (8.4 GHz).

  15. Design and Validation of High Date Rate Ka-Band Software Defined Radio for Small Satellite

    Science.gov (United States)

    Xia, Tian

    2016-01-01

    The Design and Validation of High Date Rate Ka- Band Software Defined Radio for Small Satellite project will develop a novel Ka-band software defined radio (SDR) that is capable of establishing high data rate inter-satellite links with a throughput of 500 megabits per second (Mb/s) and providing millimeter ranging precision. The system will be designed to operate with high performance and reliability that is robust against various interference effects and network anomalies. The Ka-band radio resulting from this work will improve upon state of the art Ka-band radios in terms of dimensional size, mass and power dissipation, which limit their use in small satellites.

  16. High Performance Ka-band Phase Shifters for Space Telecommunications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a novel MEMS-based digital phase shifter targeted for Ka-band operation, but scalable down to X-band and up to W-band. This novel phase shifter will...

  17. MMIC for High-Efficiency Ka-BAnd GaN Power Amplifiers (2007043) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal addresses the need for high-efficiency, high-output power amplifiers operating in the Ka-band frequencies. For space communications, the power...

  18. Advances in Ka-Band Communication System for CubeSats and SmallSats

    Science.gov (United States)

    Kegege, Obadiah; Wong, Yen F.; Altunc, Serhat

    2016-01-01

    A study was performed that evaluated the feasibility of Ka-band communication system to provide CubeSat/SmallSat high rate science data downlink with ground antennas ranging from the small portable 1.2m/2.4m to apertures 5.4M, 7.3M, 11M, and 18M, for Low Earth Orbit (LEO) to Lunar CubeSat missions. This study included link analysis to determine the data rate requirement, based on the current TRL of Ka-band flight hardware and ground support infrastructure. Recent advances in Ka-band transceivers and antennas, options of portable ground stations, and various coverage distances were included in the analysis. The link/coverage analysis results show that Cubesat/Smallsat missions communication requirements including frequencies and data rates can be met by utilizing Near Earth Network (NEN) Ka-band support with 2 W and high gain (>6 dBi) antennas.

  19. High Performance Ka Band Power Amplifiers for Future EVA Radio Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposal, AlphaSense, Inc. and the University of Washington detail the development of a novel, high performance Ka band power amplifier for EVA radio...

  20. High-power X- and Ka-band Gallium Nitride Amplifiers with Exceptional Efficiency Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Achieving very high-power amplification with maximum efficiency at X- and Ka-band is challenging using solid-state technology. Gallium Arsenide (GaAs) has been the...

  1. Ka Band Parabolic Deployable Antenna (KaPDA) for Interplanetary CubeSat Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Ka Band Parabolic Deployable Antenna (KaPDA) for Interplanetary CubeSat Communications allowing moving up from UHF, S or X to get higher gain for a given diameter.

  2. NASA's Evolution to Ka-Band Space Communications for Near-Earth Spacecraft

    Science.gov (United States)

    McCarthy, Kevin; Stocklin, Frank; Geldzahler, Barry; Friedman, Daniel; Celeste, Peter

    2010-01-01

    This slide presentation reviews the exploration of NASA using a Ka-band system for spacecraft communications in Near-Earth orbits. The reasons for changing to Ka-band are the higher data rates, and the current (X-band spectrum) is becoming crowded. This will require some modification to the current ground station antennas systems. The results of a Request for Information (RFI) are discussed, and the recommended solution is reviewed.

  3. REAL-TIME FADE MITIGATION USING RADIOMETRIC MEASUREMENTS FOR FUTURE KA-BAND SERVICES AT DLR.

    OpenAIRE

    2009-01-01

    Due to the congestion of popular C- and Ku-band frequencies, the satellite communication systems are rapidly moving toward the higher frequencies. Most of the commercial communication satellites in the near future will operate Ka-band transponders. One of the inevitable part of such systems are ground stations which support In-Orbit-testing and the traffic routine for the satellites. The main problem at Ka-band link planning is the link availability reduction due to rain fade and scintillatio...

  4. The Potential for a Ka-band (32 GHz) Worldwide VLBI Network

    Science.gov (United States)

    Jacobs, C. S.; Bach, U.; Colomer, F.; Garcia-Miro, C.; Gomez-Gonzalez, J.; Gulyaev, S.; Horiuchi, S.; Ichikawa, R.; Kraus, A.; Kronschnabl, G.; Lopez-Fernandez, J. A.; Lovell, J.; Majid, W.; Natusch, T.; Neidhardt, A.; Phillips, C.; Porcas, R.; Romero-Wolf, A.; Saldana, L.; Schreiber, U.; Sotuela, I.; Takeuchi, H.; Trinh, J.; Tzioumis, A.; deVincente, P.

    2012-01-01

    Ka-band (32 GHz, 9mm) Very Long Baseline Interferometric (VLBI) networking has now begun and has tremendous potential for expansion over the next few years. Ka-band VLBI astrometry from NASA's Deep Space Network has already developed a catalog of 470 observable sources with highly accurate positions. Now, several antennas worldwide are planning or are considering adding Ka-band VLBI capability. Thus, there is now an opportunity to create a worldwide Ka-band network with potential for high resolution imaging and astrometry. With baselines approaching a Giga-lambda, a Ka-band network would be able to probe source structure at the nano-radian (200 as) level ( 100X better than Hubble) and thus gain insight into the astrophysics of the most compact regions of emission in active galactic nuclei. We discuss the advantages of Ka-band, show the known sources and candidates, simulate projected baseline (uv) coverage, and discuss potential radio frequency feeds. The combination of these elements demonstrates the feasibility of a worldwide Ka network within the next few years!

  5. A Ka-band Celestial Reference Frame with Applications to Deep Space Navigation

    Science.gov (United States)

    Jacobs, Christopher S.; Clark, J. E.; García-Miró, C.; Horiuchi, S.; Sotuela, I.

    2011-10-01

    The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of ~200 micro-arcsec (μas) in α cos δ and ~300 μas in δ. There is evidence for systematic errors at the 100 μas level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

  6. A Ka-Band Celestial Reference Frame with Applications to Deep Space Navigation

    Science.gov (United States)

    Jacobs, Christopher S.; Clark, J. Eric; Garcia-Miro, Cristina; Horiuchi, Shinji; Sotuela, Ioana

    2011-01-01

    The Ka-band radio spectrum is now being used for a wide variety of applications. This paper highlights the use of Ka-band as a frequency for precise deep space navigation based on a set of reference beacons provided by extragalactic quasars which emit broadband noise at Ka-band. This quasar-based celestial reference frame is constructed using X/Ka-band (8.4/32 GHz) from fifty-five 24-hour sessions with the Deep Space Network antennas in California, Australia, and Spain. We report on observations which have detected 464 sources covering the full 24 hours of Right Ascension and declinations down to -45 deg. Comparison of this X/Ka-band frame to the international standard S/X-band (2.3/8.4 GHz) ICRF2 shows wRMS agreement of approximately 200 micro-arcsec in alpha cos(delta) and approximately 300 micro-arcsec in delta. There is evidence for systematic errors at the 100 micro-arcsec level. Known errors include limited SNR, lack of instrumental phase calibration, tropospheric refraction mis-modeling, and limited southern geometry. The motivation for extending the celestial reference frame to frequencies above 8 GHz is to access more compact source morphology for improved frame stability and to support spacecraft navigation for Ka-band based NASA missions.

  7. The Potential for a Ka-band (32 GHz) Worldwide VLBI Network

    Science.gov (United States)

    Jacobs, C. S.; Bach, U.; Colomer, F.; Garcia-Miro, C.; Gomez-Gonzalez, J.; Gulyaev, S.; Horiuchi, S.; Ichikawa, R.; Kraus, A.; Kronschnabl, G.; hide

    2012-01-01

    Ka-band (32 GHz, 9mm) Very Long Baseline Interferometric (VLBI) networking has now begun and has tremendous potential for expansion over the next few years. Ka-band VLBI astrometry from NASA's Deep Space Network has already developed a catalog of 470 observable sources with highly accurate positions. Now, several antennas worldwide are planning or are considering adding Ka-band VLBI capability. Thus, there is now an opportunity to create a worldwide Ka-band network with potential for high resolution imaging and astrometry. With baselines approaching a Giga-lambda, a Ka-band network would be able to probe source structure at the nano-radian (200 as) level ( 100X better than Hubble) and thus gain insight into the astrophysics of the most compact regions of emission in active galactic nuclei. We discuss the advantages of Ka-band, show the known sources and candidates, simulate projected baseline (uv) coverage, and discuss potential radio frequency feeds. The combination of these elements demonstrates the feasibility of a worldwide Ka network within the next few years!

  8. Reduction of the Resolution Losses in Dual-Wavelength Storage

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-Zheng; ZHGNG Guang-Yin; HUANG Hui; LIU Si-Min; Nouel Y. Kamber; LI Fei-Fei; SUN Qian; XU Jing-Jun

    2000-01-01

    The dual-wavelength storage for multi-page storage with the nondestructive readout is investigated in the double doped lithium niobate crystals. The image field losses are minimized by adjusting the readout wave vectors, and the resolution is improved by optimizing the storage setup.

  9. Initial research of dual wavelength fibre optic perimeter sensor

    Science.gov (United States)

    Zyczkowski, M.; Kondrat, M.; Ciurapinski, W.

    2005-10-01

    The dual wavelength fibre optic perimeter sensor bases on input signals measurements in an arrangement of fibre optic Michelson and Sagnac interferometers with a 3 × 3 coupler and two semiconductor lasers. For 3 km long sensor we obtained 20-50m resolution of determination of disturbance point.

  10. Ka-band Technologies for Small Spacecraft Communications via Relays and Direct Data Downlink

    Science.gov (United States)

    Budinger, James M.; Niederhaus, Charles; Reinhart, Richard; Downey, Joe; Roberts, Anthony

    2016-01-01

    As the scientific capabilities and number of small spacecraft missions in the near Earth region increase, standard yet configurable user spacecraft terminals operating in Ka-band are needed to lower mission cost and risk and enable significantly higher data return than current UHF or S-band terminals. These compact Ka-band terminals are intended to operate with both the current and next generation of Ka-band relay satellites and via direct data communications with near Earth tracking terminals. This presentation provides an overview of emerging NASA-sponsored and commercially provided technologies in software defined radios (SDRs), transceivers, and electronically steered antennas that will enable data rates from hundreds of kbps to over 1 Gbps and operate in multiple frequency bands (such as S- and X-bands) and expand the use of NASA's common Ka-bands frequencies: 22.55-23.15 GHz for forward data or uplink; and 25.5-27.0 GHz for return data or downlink. Reductions in mass, power and volume come from integration of multiple radio functions, operations in Ka-band, high efficiency amplifiers and receivers, and compact, flat and vibration free electronically steered narrow beam antennas for up to + 60 degrees field of regard. The software defined near Earth space transceiver (SD-NEST) described in the presentation is intended to be compliant with NASA's space telecommunications radio system (STRS) standard for communications waveforms and hardware interoperability.

  11. Overview of Ka-band communications technology requirements for the space exploration initiative

    Science.gov (United States)

    Miller, Edward F.

    1991-12-01

    In the Space Exploration Initiative, Ka-band frequencies are likely to carry the bulk of the communications traffic both in the vicinity of and on the return links from the moon and Mars. The four exploration architectures identified by the Synthesis Group are examined and Ka-band technology requirements to meet the data traffic needs and schedule are identified. Specific Ka-band technology requirements identified are: transmitters - 0.5 to 200 W with high efficiency; antennas - 5m and 9m diameter, with multiple beams and/or scanning beams; and spacecraft receivers - noise figure of 2 dB. For each component, the current state of technology is assessed and needed technology development programs are identified. It is concluded that to meet the schedules of lunar and Mars precursor missions beginning in approximately the year 2000, aggressive technology development and advanced development programs are required immediately for Ka-band communications systems components. Additionally, the greater data transmission rates for the cargo and piloted phases of the exploration program require further Ka-band communications technology developments targeted for operations beginning in about 2010.

  12. Fabrication of band-pass filter using YBCO film at Ka-band frequency; YBCO hakumaku wo mochiita Ka-band taiiki tsuka fuiruta no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Yoshitake, T.; Hattori, W.; Murakami, S.; Suzuki, S. [NEC Corp., Tokyo (Japan)

    1999-11-10

    In this report, Ka band microstrip band pass filter was produced experimentally using an YBCO system high temperature superconductivity thin film as examination initial stage high temperature superconductivity a thin film superscription communication element. With it, the following were examined: Evaluation method and frequency characteristics of the filter. Especially, the examination on structure of the package and system of measurement using refrigerating machine becomes important in order to evaluate the filter with the high frequency. (NEDO)

  13. Design of a Ka-Band Propagation Terminal for Atmospheric Measurements in Polar Regions

    Science.gov (United States)

    Houts, Jacquelynne R.; Nessel, James A.; Zemba, Michael J.

    2016-01-01

    This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer [2] located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation [3] receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation by directly measuring the propagated signal from the satellite Thor 7.

  14. Mars Reconnaissance Orbiter: Ka Band Radio Science Experiments and the Effect of the Troposphere

    Science.gov (United States)

    Asmar, Sami W.; Morabito, David

    2006-01-01

    This viewgraph presentation reviews the possibilities of utilizing the telecommunication links between spacecraft and Earth to examine changes in the phase/frequency, amplitude, and polarization of radio signals to investigate, specifically for the Mars Reconnaissance Orbiter (MRO)mission utilizes X-band coherent (uplink and downlink) carrier Doppler and range for its gravity investigation Gravity team will also take advantage of Ka-band downlink signal Tropospheric calibration data from Advanced Water Vapor Radiometer (AWVR) will be used. The calibration of the received Ka band signal for the effect of the troposphere is discussed.

  15. The Mars Global Surveyor Ka-Band Link Experiment (MGS/KaBLE-II)

    Science.gov (United States)

    Morabito, D.; Butman, S.; Shambayati, S.

    1999-01-01

    The Mars Global Surveyor (MGS) spacecraft, launched on November 7, 1996, carries an experimental space-to-ground telecommunications link at Ka-band (32 GHz) along with the primary X-band (8.4-GHz) downlink. The signals are simultaneously transmitted from a 1.5-m-diameter parabolic antenna on MGS and received by a beam-waveguide (BWG) research and development (R&D) 34-meter a ntenna located in NASA's Goldstone Deep Space Network (DSN) complex near Barstow, California. This Ka-band link experiment (KaBLE-II) allows the performances of the Ka-band and X-band signals to be compared under nearly identical conditions. The two signals have been regularly tracked during the past 2 years. This article presents carrier-signal-level data (P_c/N_o) for both X-band and Ka-band acquired over a wide range of station elevation angles, weather conditions, and solar elongation angles. The cruise phase of the mission covered the period from launch (November 7, 1996) to Mars orbit capture (September 12, 1997). Since September 12, 1997, MGS has been in orbit around Mars. The measurements confirm that Ka-band could increase data capacity by at least a factor of three (5 dB) as compared with X-band. During May 1998, the solar corona experiment, in which the effects of solar plasma on the X-band and Ka-band links were studied, was conducted. In addition, frequency and difference frequency (f_x - f_(Ka)/3.8), ranging, and telemetry data results are presented. MGS/KaBLE-II measured signal strengths (for 54 percent of the experiments conducted) that were in reasonable agreement with predicted values based on preflight knowledge, and frequency residuals that agreed between bands and whose statistics were consistent with expected noise sources. For passes in which measured signal strengths disagreed with predicted values, the problems were traced to known deficiencies, for example, equipment operating under certain conditions, such as a cold Ka-band solid-state power amplifier (SSPA

  16. Design of a Ka-band Propagation Terminal for Atmospheric Measurements in Polar Regions

    Science.gov (United States)

    Houts, Jacquelynne R.; Nessel, James A.; Zemba, Michael J.

    2016-01-01

    This paper describes the design and performance of a Ka-Band beacon receiver developed at NASA Glenn Research Center (GRC) that will be installed alongside an existing Ka-Band Radiometer located at the east end of the Svalbard Near Earth Network (NEN) complex. The goal of this experiment is to characterize rain fade attenuation to improve the performance of existing statistical rain attenuation models. The ground terminal developed by NASA GRC utilizes an FFT-based frequency estimation receiver capable of characterizing total path attenuation effects due to gaseous absorption, clouds, rain, and scintillation by directly measuring the propagated signal from the satellite Thor 7.

  17. Mars Reconnaissance Orbiter: Ka Band Radio Science Experiments and the Effect of the Troposphere

    Science.gov (United States)

    Asmar, Sami W.; Morabito, David

    2006-01-01

    This viewgraph presentation reviews the possibilities of utilizing the telecommunication links between spacecraft and Earth to examine changes in the phase/frequency, amplitude, and polarization of radio signals to investigate, specifically for the Mars Reconnaissance Orbiter (MRO)mission utilizes X-band coherent (uplink and downlink) carrier Doppler and range for its gravity investigation Gravity team will also take advantage of Ka-band downlink signal Tropospheric calibration data from Advanced Water Vapor Radiometer (AWVR) will be used. The calibration of the received Ka band signal for the effect of the troposphere is discussed.

  18. Linear programming phase unwrapping for dual-wavelength digital holography.

    Science.gov (United States)

    Wang, Zhaomin; Jiao, Jiannan; Qu, Weijuan; Yang, Fang; Li, Hongru; Tian, Ailing; Asundi, Anand

    2017-01-20

    A linear programming phase unwrapping method in dual-wavelength digital holography is proposed and verified experimentally. The proposed method uses the square of height difference as a convergence standard and theoretically gives the boundary condition in a searching process. A simulation was performed by unwrapping step structures at different levels of Gaussian noise. As a result, our method is capable of recovering the discontinuities accurately. It is robust and straightforward. In the experiment, a microelectromechanical systems sample and a cylindrical lens were measured separately. The testing results were in good agreement with true values. Moreover, the proposed method is applicable not only in digital holography but also in other dual-wavelength interferometric techniques.

  19. Computer Aided Design of Ka-Band Waveguide Power Combining Architectures for Interplanetary Spacecraft

    Science.gov (United States)

    Vaden, Karl R.

    2006-01-01

    Communication systems for future NASA interplanetary spacecraft require transmitter power ranging from several hundred watts to kilowatts. Several hybrid junctions are considered as elements within a corporate combining architecture for high power Ka-band space traveling-wave tube amplifiers (TWTAs). This report presents the simulated transmission characteristics of several hybrid junctions designed for a low loss, high power waveguide based power combiner.

  20. Results from Two Years of Ka-Band Propagation Characterization at Svalbard, Norway

    Science.gov (United States)

    Nessel, James A.; Morse, Jacquelynne Rose; Zemba, Michael

    2014-01-01

    Over the several years, NASA plans to launch several earth science missions which are expected to achieve data throughputs of 5-40 terabits per day transmitted from low earth orbiting spacecraft to ground stations. The current S-band and X-band frequency allocations in use by NASA, however, are incapable of supporting the data rates required to meet this demand. As such, NASA is in the planning stages to upgrade its existing Near Earth Network (NEN) Polar ground stations to support Ka-band (25.5-27 GHz) operations. Consequently, it becomes imperative that characterization of propagation effects at these NEN sites is conducted to determine expected system performance, particularly at low elevation angles ((is) less than 10 deg) where spacecraft signal acquisition typically occurs. Since May 2011, NASA Glenn Research Center has installed and operated a Ka-band radiometer at the NEN site located in Svalbard, Norway. The Ka-band radiometer monitors the water vapor line, as well as 6 frequencies around 26.5 GHz at multiple elevation angles: 45 deg, 20 deg, and 10 deg. Two year data collection results indicate comparable performance to previously characterized northern latitude sites in the United States, i.e., Fairbanks, Alaska. It is observed that cloud cover at the Svalbard site remains the dominant loss mechanism for Ka-band links, resulting in a margin requirement of 4.1 dB to maintain link availability of 99% at 10 deg elevation.

  1. Steerable K/Ka-Band Antenna For Land-Mobile Satellite Applications

    Science.gov (United States)

    Densmore, Arthur; Jamnejad, Vahraz; Woo, Kenneth

    1994-01-01

    Prototype steerable microwave antenna tracks and communicates with geostationary satellite. Designed to mount on roof of vehicle and only 10 cm tall. K/Ka-band antenna rugged and compact to suit rooftop mobile operating environment. More-delicate signal-processing and control equipment located inside vehicle.

  2. Evaluation and Performance Analysis of 3D Printing Technique for Ka-Band Antenna Production

    DEFF Research Database (Denmark)

    Armendariz, Unai; Rommel, Simon; Rodríguez Páez, Juan Sebastián

    2016-01-01

    This paper presents the design and fabrication of 3D printed WR-28 waveguide horn antennas operating in the Ka-band frequency range between 26.5GHz and 40GHz. Three antennas are fabricated from polylactide acid filaments in conductive and non-conductive variants; the latter is covered...

  3. SYSTEM MODELLING OF DTH BROADCASTING AT KA BAND MULTIBEAM SATELLITE SYSTEM OVER INDIA

    Directory of Open Access Journals (Sweden)

    Swastik Sahoo

    2015-12-01

    Full Text Available A major application of satellite is broadcasting and in India this is done at Ku band. But with the increase of demand of number of channels Ku band is getting saturated. So, to satisfy this requirement an approach is to go to higher frequency band, i.e. Ka band. As India is allocated with seven fixed GEO locations, so the purpose is to calculate what is the suitable satellite position for India at Ka band, what is the best EIRP available at that position and what will be the smallest ground antenna diameter and satellite antenna diameter at Ka band. Broadcasting is done at 20GHz Ka band downlink frequency. At this frequency, as the signal will face lots of impairments during propagation, so the attenuation caused by variety of factors are discussed here. To overcome the attenuation maximum EIRP is given. The link equation is taken as a reference to calculate quality of the signal, G/T ratio and EIRP of the satellite. The extreme west region of India is being taken as earth station and after some brief calculations all the results are discussed. Out of seven allocated GEO locations, 74⁰E gives best output in terms of minimum loss & small antenna diameters.

  4. Design of a Ka-band gyro-TWT amplifier for broadband operation

    Energy Technology Data Exchange (ETDEWEB)

    Alaria, Mukesh Kumar; Sinha, A. K. [Microwave Tubes Area, CSIR-Central Electronics Engineering Research Institute, Pilani 333031 (India); Choyal, Y. [Department of Physics, Devi Ahilya Vishwavidyalaya, Indore (India)

    2013-07-15

    In this paper, the design of a Ka-band periodically ceramic loaded gyro-TWT amplifier has been carried out. The design predict that the interaction structure can produce more than 80 kW output power, 50 dB saturated gain, and 3 dB bandwidth for 65 kV and 5 A electron beam with velocity ratio (α) of 1.2. This paper describes the design and simulation of a high performance 35 GHz TE{sub 01} mode gyro-TWT that applies the same technique of employing a periodic dielectric loaded interaction structure to achieve stability and wide bandwidth. The design of input coupler with loaded interaction structure for Ka-band Gyro-TWT has been carried out using Ansoft hfss. The return loss (S{sub 11}) and transmission loss (S{sub 21}) of the Ka-band gyro-TWT input coupler have been found to be −27.3 dB and −0.05 dB, respectively. The design of output window for Ka-band Gyro-TWT has been carried out using cst microwave studio.

  5. High Power High Efficiency Ka-Band Power Combiners for Solid-State Devices

    Science.gov (United States)

    Freeman, Jon C.; Wintucky, Edwin G.; Chevalier, Christine T.

    2006-01-01

    Wide-band power combining units for Ka-band are simulated for use as MMIC amplifier applications. Short-slot couplers as well as magic-tees are the basic elements for the combiners. Wide bandwidth (5 GHz) and low insertion (approx.0.2 dB) and high combining efficiencies (approx.90 percent) are obtained.

  6. Performance of a Ka-band transponder breadboard for deep-space applications

    Science.gov (United States)

    Mysoor, N. R.; Lane, J. P.; Kayalar, S.; Kermode, A. W.

    1995-08-01

    This article summarizes the design concepts applied in the development of and advanced Ka-band (34.4 GHz/32 GHz) transponder breadboard for the next generation of space communications systems applications. The selected architecture upgrades the X-band (7.2 GHz/8.4 GHz) deep-space transponder (DST) to provide Da-band up/Ka- and X-band down capability. The Ka-band transponder breadboard incorporates several state-of-the-art components, including sampling mixers, a Ka-band dielectric resonator oscillator, and microwave monolithic integrated circuits (MMICs). The MMICs that were tested in the breadboard include upconverters, downconverters, automatic gain control circuits, mixers, phase modulators, and amplifiers. The measured receiver dynamic range, tracking range, acquisition rate, static phase error, and phase jitter characteristics of the Ka-band breadboard interfaced to the advanced engineering model X-band DST are in good agreement with the expected performance. The results show a receiver tracking threshold of -149 dBm with a dynamic range of 80 dB and a downlink phase jitter of 7 deg rms. The analytical results of phase noise and Allan standard deviation are in good agreement with the experimental results.

  7. Ka-Band PAA for Satellite Telemetry System for RLVs & Aircraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed antenna is a Radial-Waveguide Array (RWA) that will operate at Ka band, 25.5-27.5 GHz in transmit and receive for left-hand, right-hand. This Phase I...

  8. Results from Three Years of Ka-Band Propagation Characterization at Svalbard, Norway

    Science.gov (United States)

    Nessel, James; Zemba, Michael; Morse, Jacquelynne

    2015-01-01

    Over the next several years, NASA plans to launch several earth science missions which are expected to achieve data throughputs of 5-40 terabits per day transmitted from low earth orbiting spacecraft to ground stations. The current S-band and X-band frequency allocations in use by NASA, however, are incapable of supporting the data rates required to meet this demand. As such, NASA is in the planning stages to upgrade its existing Near Earth Network (NEN) polar ground stations to support Ka-band (25.5-27 GHz) operations. Consequently, it installed and operated a Ka-band radiometer at the Svalbard site. Svalbard was chosen as the appropriate site for two primary reasons: (1) Svalbard will be the first site to be upgraded to Ka-band operations within the NEN Polar Network enhancement plan, and (2) there exists a complete lack of Ka-band propagation data at this site (as opposed to the Fairbanks, AK NEN site, which has 5 years of characterization collected during the Advanced Communications Technology becomes imperative that characterization of propagation effects at these NEN sites is conducted to determine expected system Satellite (ACTS) campaign). processing and provide the Herein, we discuss the data three-year measurement results performance, particularly at low elevation angles ((is) less than 10 deg) from the ongoing Ka-band propagation characterization where spacecraft signal acquisition typically occurs. Since May 2011, NASA Glenn Research Center has installed and operated a Ka-band radiometer at the NEN site located in Svalbard, Norway. The Ka-band radiometer monitors the water vapor line, as well as 4 frequencies around 26.5 GHz at a fixed 10 deg elevation angle. Three-year data collection results indicate good campaign at Svalbard, Norway. Comparison of these results with the ITU models and existing ERA profile data indicates very good agreement when the 2010 rain maps and cloud statistics are used. Finally, the Svalbard data is used to derive the expected

  9. Experimental characterization of negative refractive index material NRM at Ka band

    CERN Document Server

    Chatterjee, Sougata

    2016-01-01

    In this paper, we discuss the experimental characterization of a negative refractive material NRM at Ka band using LR labyrinth Ring and wire array WA. We describe in detail the the LR and wire array characterization separately, and after that the combined experimental results, for NRM are reported. The LRs analytical and simulation study is not new but design in Ka band and different experimental procedure for the characterization of the negative refractive index is the novelty of this paper. For performing a negative refractive index experiment we made prism of 150 Prism angle . We get enhanced transmittance of more than 20 dB from background, at a negative angle of refraction. The values of the negative refractive index in a band of about 1 G Hz around 31 GHz are retrieved from the experimental data.

  10. DESIGN, FABRICATION AND RF CHARACTERIZATION OF KA-BAND SILICON IMPATT DIODE

    Directory of Open Access Journals (Sweden)

    TAPAS KUMAR PAL,

    2010-09-01

    Full Text Available A silicon (p+nn+ SDR IMPATT diode for Ka-band operation has been designed by using a double iterative DC and Small signal simulation which involves simultaneous solution of Poisson’s equation and Carrier continuity equation, satisfying appropriate boundary conditions in the depletion layer edges. Using the design parameters,silicon epitaxial n/n+ wafers of appropriate thickness and resistivity of the epitaxial layer have been selected for fabrication of (p+nn+ SDR IMPATT diode for Ka-band operation. The (p+nn+ SDR IMPATT diode has been fabricated through diffusion technique. The optimized process steps of fabrication, starting from wafer cleaningto packaging have been described in details. The DC V-I and RF characteristics of fabricated IMPATT diode have been measured by using an integrated heat sink cum resonant cap waveguide cavity.

  11. Reconfigurable phased antenna array for extending cubesat operations to Ka-band: Design and feasibility

    Science.gov (United States)

    Buttazzoni, G.; Comisso, M.; Cuttin, A.; Fragiacomo, M.; Vescovo, R.; Vincenti Gatti, R.

    2017-08-01

    Started as educational tools, CubeSats have immediately encountered the favor of the scientific community, subsequently becoming viable platforms for research and commercial applications. To ensure competitive data rates, some pioneers have started to explore the usage of the Ka-band beside the conventional amateur radio frequencies. In this context, this study proposes a phased antenna array design for Ka-band downlink operations consisting of 8×8 circularly polarized subarrays of microstrip patches filling one face of a single CubeSat unit. The conceived structure is developed to support 1.5 GHz bandwidth and dual-task missions, whose feasibility is verified by proper link budgets. The dual-task operations are enabled by a low-complexity phase-only control algorithm that provides pattern reconfigurability in order to satisfy both orbiting and intersatellite missions, while remaining adherent to the cost-effective CubeSat paradigm.

  12. A satellite system for multimedia personal communications at Ka-band and beyond

    Science.gov (United States)

    Vatalaro, F.; Losquadro, G.

    1995-01-01

    The main characteristics of the satellite extremely high frequency (EHF) communication of multimedia mobile services (SECOMS) system are given and the results of the preliminary analysis are included. The SECOMS provides a first generation Ka band system with coverage over Western Europe, in order to satisfy business user needs of very large bandwidths and terminal mobility. The satellite system also provides a second generation EHF enhanced system with increased capacity and enlarged coverage, to serve all of Europe and the nearby countries.

  13. A K/Ka band radiating element for Tx/Rx phased array

    KAUST Repository

    Sandhu, Ali Imran

    2017-01-20

    The paper presents a K/Ka band radiating element for TX/RX phased arrays. Dual band operations is obtained using a single radiating surface: a novel radiator is adopted and placed in a configuration in which dual band and single band elements are interleaved. The array elements are optimized to scan the beam in excess of 50° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

  14. Inverse-Gaussian-Apodized Fiber Bragg Grating for Dual Wavelength Lasing

    CERN Document Server

    Lin, Bo; Tjin, Swee Chuan; Tang, Dingyuan; Hao, Jianzhong; Tay, Chia Meng; Liang, Sheng

    2010-01-01

    A fiber Bragg grating (FBG) with an inverse-Gaussian apodization function is proposed and fabricated. It is shown that such a FBG possesses easily controllable dual-wavelength narrow transmission peaks. Incorporating such a FBG filter in a fiber laser with a linear cavity, stable dual-wavelength emission with 0.146 nm wavelength spacing is obtained. It provides a simple and low cost approach of achieving the dual-wavelength fiber laser operation.

  15. A Wide-band, Ka-band Amplifier and Radar System for Precipitation Retrievals Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA is committed to measuring precipitation on a global scale. In 1997, NASA launched the Tropical Rain Measuring Mission which carried the first spaceborne...

  16. Dual-wavelength laser source for onboard atom interferometry.

    Science.gov (United States)

    Ménoret, V; Geiger, R; Stern, G; Zahzam, N; Battelier, B; Bresson, A; Landragin, A; Bouyer, P

    2011-11-01

    We present a compact and stable dual-wavelength laser source for onboard atom interferometry with two different atomic species. It is based on frequency-doubled telecom lasers locked on a femtosecond optical frequency comb. We take advantage of the maturity of fiber telecom technology to reduce the number of free-space optical components, which are intrinsically less stable, and to make the setup immune to vibrations and thermal fluctuations. The source provides the frequency agility and phase stability required for atom interferometry and can easily be adapted to other cold atom experiments. We have shown its robustness by achieving the first dual-species K-Rb magneto-optical trap in microgravity during parabolic flights.

  17. Dual-wavelength laser source for onboard atom interferometry

    CERN Document Server

    Ménoret, Vincent; Stern, Guillaume; Zahzam, Nassim; Battelier, Baptiste; Bresson, Alexandre; Landragin, Arnaud; Bouyer, Philippe

    2011-01-01

    We present a compact and stable dual-wavelength laser source for onboard atom interferometry with two different atomic species. It is based on frequency-doubled telecom lasers locked on a femtosecond optical frequency comb. We take advantage of the maturity of fiber telecom technology to reduce the number of free-space optical components which are intrinsically less stable, and to make the setup immune to vibrations and thermal fluctuations. The source provides the frequency agility and phase stability required for atom interferometry and can easily be adapted to other cold atom experiments. We have shown its robustness by achieving the first dual-species K-Rb magneto optical trap in microgravity during parabolic flights.

  18. Miniaturized UHF, S-, and Ka-band RF MEMS Filters for Small Form Factor, High Performance EVA Radio Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase II of this SBIR, Harmonic Devices (HDI) proposes to develop miniaturized MEMS filters at UHF, S-band and Ka-band to address the requirements of NASA's...

  19. High-Efficiency, Ka-band Solid-State Power Amplifier Utilizing GaN Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — QuinStar Technology proposes to develop an efficient, solid-state power amplifier (SSPA), operating at Ka-band frequencies, for high data rate, long range space...

  20. Ka-Band Site Characterization of the NASA Near Earth Network in Svalbard, Norway

    Science.gov (United States)

    Acosta, R.; Morse, J.; Nessel, J.; Zemba, M.; Tuttle, K.; Caroglanian, A.; Younes, B.; Pedersen, Sten-Chirstian

    2011-01-01

    Critical to NASA s rapid migration toward Ka-Band is the comprehensive characterization of the communication channels at NASA's ground sites to determine the effects of the atmosphere on signal propagation and the network's ability to support various classes of users in different orbits. Accordingly, NASA has initiated a number of studies involving the ground sites of its Near Earth and Deep Space Networks. Recently, NASA concluded a memorandum of agreement (MOA) with the Norwegian Space Centre of the Kingdom of Norway and began a joint site characterization study to determine the atmospheric effects on Ka-Band links at the Svalbard Satellite Station in Norway, which remains a critical component of NASA s Near Earth Communication Network (NEN). System planning and design for Ka-band links at the Svalbard site cannot be optimally achieved unless measured attenuation statistics (e.g. cumulative distribution functions (CDF)) are obtained. In general, the CDF will determine the necessary system margin and overall system availability due to the atmospheric effects. To statistically characterize the attenuation statistics at the Svalbard site, NASA has constructed a ground-based monitoring station consisting of a multi-channel total power radiometer (25.5 - 26.5 GHz) and a weather monitoring station to continuously measure (at 1 second intervals) attenuation and excess noise (brightness temperature). These instruments have been tested in a laboratory environment as well as in an analogous outdoor climate (i.e. winter in Northeast Ohio), and the station was deployed in Svalbard, Norway in May 2011. The measurement campaign is planned to last a minimum of 3 years but not exceeding a maximum of 5 years.

  1. Proposal for a Joint NASA/KSAT Ka-band RF Propagation Terminal at Svalbard, Norway

    Science.gov (United States)

    Volosin, Jeffrey; Acosta, Roberto; Nessel, James; McCarthy, Kevin; Caroglanian, Armen

    2010-01-01

    This slide presentation discusses the placement of a Ka-band RF Propagation Terminal at Svalbard, Norway. The Near Earth Network (NEN) station would be managed by Kongsberg Satellite Services (KSAT) and would benefit NASA and KSAT. There are details of the proposed NASA/KSAT campaign, and the responsibilities each would agree to. There are several reasons for the placement, a primary reason is comparison with the Alaska site, Based on climatological similarities/differences with Alaska, Svalbard site expected to have good radiometer/beacon agreement approximately 99% of time.

  2. Ka-band Dielectric Waveguide Antenna Array for Millimeter Wave Active Imaging System

    Science.gov (United States)

    Fang, Weihai; Fei, Peng; Nian, Feng; Yang, Yujie; Feng, Keming

    2014-11-01

    Ka-band compact dielectric waveguide antenna array for active imaging system is given. Antenna array with WR28 metal waveguide direct feeding is specially designed with small size, high gain, good radiation pattern, easy realization, low insertion loss and low mutual coupling. One practical antenna array for 3-D active imaging system is shown with theoretic analysis and experimental results. The mutual coupling of transmitting and receiving units is less than -30dB, the gain from 26.5GHz to 40GHz is (12-16) dB. The results in this paper provide guidelines for the designing of millimeter wave dielectric waveguide antenna array.

  3. Particle simulation of a ka-band gyrotron traveling wave amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shouxi; Liu Pukun; Zhang Shichang; Du Chaohai; Xue Qianzhong; Geng Zhihui; Su Yinong [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, P.O. Box 2652, Beijing 100190 (China)

    2011-08-15

    The design of a ka-band gyrotron traveling wave (gyro-TWT) amplifier is presented. The gyro-TWT amplifier with a severed structure operates in the fundamental harmonic TE{sub 01} circular electric mode. The beam-wave interaction is studied by using a particle-in-cell (PIC) code. The simulations predict that the amplifier can produce an output peak power of over 155 kW, 22% efficiency, 23 dB gain, and a 3 dB bandwidth of 2 GHz for a 70 kV, 10 A electron beam with an axial velocity spread {Delta}v{sub z}/v{sub z}=5%.

  4. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    Directory of Open Access Journals (Sweden)

    S. Coco

    2008-01-01

    Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.

  5. A CDMA architecture for a Ka-band Personal Access Satellite System

    Science.gov (United States)

    Motamedi, Masoud; Sue, Miles K.

    1990-01-01

    A Code Division Multiple Access (CDMA) architecture is currently being studied for use in a Ka-band Personal Access Satellite System (PASS). The complete architecture consisting of block diagrams of the user terminal, the supplier station, the network management center, and the satellite is described along with the access methods and frequency/time plans. The complexity of developing this system using the CDMA architecture is compared to that of a Frequency Division Multiple Access (FDMA) architecture. The inherent advantages and disadvantages of the two architectures are compared and their respective capacities are discussed.

  6. Deep-Space Ka-Band Link Priority Data Protection: Pre-Emptive Retransmission vs. Margin

    Science.gov (United States)

    Shambayati, Shervin

    2009-01-01

    In this paper the performance of two preemptive retransmission schemes for protection of priority data over deep-space Ka-band links is evaluated. The first scheme merges the correctly received bit from each transmission to create the most complete set of priority data for each pass (bit merge). The second scheme (symbol combining) combines the soft symbols received from each transmission of the priority data to increase the priority data's signal to noise ratio (SNR), thus increasing the liklihood of the correct reception.

  7. Analysis of Standards Efficiency in Digital Television Via Satellite at Ku and Ka Bands

    Directory of Open Access Journals (Sweden)

    Landeros-Ayala Salvador

    2013-06-01

    Full Text Available In this paper, an analysis on the main technical features of digital television standards for satellite transmission is carried out. Based on simulations and link budgets, the standard with the best operational performance is defined, based on simulations and link budget analysis, as well as a comparative efficiency analysis is conducted for the Ku and Ka bands for both transparent and regenerative transponders in terms of power, bandwidth, information rate and link margin, including clear sky, uplink rain, downlink rain and rain in both.

  8. Simulation and measurement of a Ka-band HTS MMIC Josephson junction mixer

    Science.gov (United States)

    Zhang, Ting; Pegrum, Colin; Du, Jia; Guo, Yingjie Jay

    2017-01-01

    We report modeling and simulation results for a Ka band high-temperature superconducting (HTS) monolithic microwave integrated circuit (MMIC) Josephson junction mixer. A Verilog-A model of a Josephson junction is established and imported into the system simulator to realize a full HTS MMIC circuit simulation containing the HTS passive circuit models. Impedance matching optimization between the junction and passive devices is investigated. Junction DC I-V characteristics, current and local oscillator bias conditions and mixing performance are simulated and compared with the experimental results. Good agreement is obtained between the simulation and measurement results.

  9. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    OpenAIRE

    Coco, S; Di Maggio, F.; A. Laudani; I. Pomona

    2008-01-01

    This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB) for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase nois...

  10. Modeling and Measurement of Phase Noise in GaAs HBT Ka-Band Oscillators

    OpenAIRE

    Lenk, Friedrich; Schott, Matthias; Heinrich, Wolfgang

    2001-01-01

    Accurate oscillator phase-noise simulation is a key problem in MMIC design, which is not solved satisfactory so far and needs further investigation. In this paper, a Ka-band MMIC oscillator with GaInP/GaAs HBT and on-chip resonator is treated as an example. Measured phase noise reaches -90 dBc/Hz and below at 100 kHz offset. To evaluate phase-noise predic-tion, the circuit is simulated using different commercial simulation tools and HBT models. Con-siderable differences in simulation results ...

  11. Evaluation of Deep Space Ka-Band Data Transfer using Radiometeorological Forecasts and Radiometer Measurements

    Science.gov (United States)

    Montopoli, Mario; Marzano, Frank S.; Biscarini, Marianna; Milani, Luca; Cimini, Domenico; De Sanctis, Klaide; Di Fabio, Saverio

    2016-04-01

    Deep space exploration is aimed at acquiring information about the solar system. In this scenario, telecommunications links between Earth ground receiving stations and extra-terrestrial satellite platforms have to be designed in order to ensure the optimal transfer of the acquired scientific data back to the Earth. A significant communication capacity has to be planned when very large distances, as those characterising deep space links, are involved thus fostering more ambitious scientific mission requirements. At the current state of the art, two microwave channel frequencies are used to perform the deep space data transfer: X band (~ 8.4 GHz) and Ka band (~ 32 GHz) channel. Ka-band transmission can offer an advantage over X-band in terms of antenna performance with the same antenna effective area and an available data transfer bandwidth (50 times higher at Ka band than X band). However, Earth troposphere-related impairments can affects the space-to-Earth carrier signals at frequencies higher than 10 GHz by degrading its integrity and thus reducing the deep space channel temporal availability. Such atmospheric impairments, especially in terms of path attenuation, their statistic and the possibility to forecast them in the next 24H at the Earth's receiving station would allow a more accurate design of the deep space link, promoting the mitigation of the detrimental effects on the link availability. To pursue this aim, meteorological forecast models and in situ measurements need to be considered in order to characterise the troposphere in terms of signal path attenuation at current and future time. In this work, we want to show how the synergistic use of meteorological forecasts, radiative transfer simulations and in situ measurements such as microwave radiometry observations, rain gauges and radiosoundings, can aid the optimisation of a deep space link at Ka band and improve its performance with respect to usual practices. The outcomes of the study are in the

  12. Continuous 1052, 1064 nm dual-wavelength Nd:YAG laser

    Science.gov (United States)

    Wang, Xiaozhong; Yuan, Haiyang; Wang, Mingshan; Huang, Wencai

    2016-10-01

    Dual-wavelength lasers are usually obtained through balancing the net gain of the two oscillating lines. Competition between transitions 1052 nm, 1061 nm and 1064 nm is utilized to realize a continuous wave 1052 and 1064 nm dual-wavelength Nd:YAG laser firstly in this paper. A specially designed Fabry-Perot band-pass filter is exploited as output coupler to control the thresholds of the oscillating wavelengths. The maximum power of the dual-wavelength laser is 1.6 W and the slope efficiency is about 10%. The power instability of the output dual-wavelength laser is smaller than ±4% in half an hour. The mechanism presented in this paper may provide a new way to obtain dual-wavelength lasers.

  13. FERROELECTRIC SWITCH FOR A HIGH-POWER Ka-BAND ACTIVE PULSE COMPRESSOR

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc.

    2013-12-18

    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  14. A Ka-band 22 dBm GaN amplifier MMIC

    Institute of Scientific and Technical Information of China (English)

    Wang Dongfang; Chen Xiaojuan; Yuan Tingting; Wei Ke; Liu Xinyu

    2011-01-01

    A Ka-band GaN amplifier MMIC has been designed in CPW technology,and fabricated with a domestic GaN epitaxial wafer and process.This is,to the best of our knowledge,the first demonstration of domestic Kaband GaN amplifier MMICs.The single stage CPW MMIC utilizes an AIGaN/GaN HEMT with a gate-length of 0.25 μm and a gate-width of 2 × 75 μm.Under Vds =10 V,continuous-wave operating conditions,the amplifier has a 1.5 GHz operating bandwidth.It exhibits a linear gain of 6.3 dB,a maximum output power of 22 dBm and a peak PAE of 9.5% at 26.5 GHz.The output power density of the AIGaN/GaN HEMT in the MMIC reaches 1 W/mm at Ka-band under the condition of Vds =10 V.

  15. A novel Ka-band coaxial transit-time oscillator with a four-gap buncher

    Energy Technology Data Exchange (ETDEWEB)

    Song, Lili; He, Juntao; Ling, Junpu [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2015-05-15

    A novel Ka-band coaxial transit-time oscillator (TTO) with a four-gap buncher is proposed and investigated. Simulation results show that an output power of 1.27 GW and a frequency of 26.18 GHz can be achieved with a diode voltage of 447 kV and a beam current of 7.4 kA. The corresponding power efficiency is 38.5%, and the guiding magnetic field is 0.6 T. Studies and analysis indicate that a buncher with four gaps can modulate the electron beam better than the three-gap buncher in such a Ka-band TTO. Moreover, power efficiency increases with the coupling coefficient between the buncher and the extractor. Further simulation demonstrates that power efficiency can reach higher than 30% with a guiding magnetic field of above 0.5 T. Besides, the power efficiency exceeds 30% in a relatively large range of diode voltage from 375 kV to 495 kV.

  16. Electromagnetic Properties of Graphene-like Films in Ka-Band

    Directory of Open Access Journals (Sweden)

    Sofia Voronovich

    2014-05-01

    Full Text Available We studied electromagnetic properties of pyrolytic carbon (PyC films with thicknesses from 9 nm to 110 nm. The PyC films consisted of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers were synthesized by chemical vapor deposition (CVD at 1100 °C on a quartz substrate. The reflectance and transmittance of these films in Ka-band, 26–37 GHz, were studied both experimentally and theoretically. The discovered remarkably high absorption loss of up to 50% of incident power, along with chemical stability, makes PyC films attractive for electromagnetic (EM interference shielding in space and airspace communication systems, as well as in portable electronic devices occupying this frequency slot. Since, in practical applications, the PyC film should be employed for coating of dielectric surfaces, two important issues to be addressed are: (i which side (front or back of the substrate should be covered to ensure maximum absorption losses; and (ii the frequency dependence of absorbance/transmittance/reflectance of binary PyC/quartz structures in the Ka-band.

  17. Ferroelectric switch for a high-power Ka-band active pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

    2013-12-18

    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  18. Ka-Band Atmospheric Phase Stability Measurements in Goldstone, CA; White Sands, NM; and Guam

    Science.gov (United States)

    Zemba, Michael J.; Morse, Jacquelynne Rose; Nessel, James A.

    2014-01-01

    As spacecraft communication links are driven to higher frequencies (e.g. Ka-band) both by spectrum congestion and the appeal of higher data rates, the propagation phenomena at these frequencies must be well characterized for effective system design. In particular, the phase stability of a site at a given frequency will govern whether or not the site is a practical location for an antenna array, particularly if uplink capabilities are desired. Propagation studies to characterize such phenomena must be done on a site-by-site basis due to the wide variety of climates and weather conditions at each ground terminal. Accordingly, in order to statistically characterize the atmospheric effects on Ka-Band links, site test interferometers (STIs) have been deployed at three of NASA's operational sites to directly measure each site's tropospheric phase stability. Using three years of results from these experiments, this paper will statistically characterize the simultaneous atmospheric phase noise measurements recorded by the STIs deployed at the following ground station sites: the Goldstone Deep Space Communications Complex near Barstow, CA; the White Sands Ground Terminal near Las Cruces, NM; and the Guam Remote Ground Terminal on the island of Guam.

  19. On the Design of Laser Structured Ka Band Multi-Chip Module

    Directory of Open Access Journals (Sweden)

    Ghulam Mehdi

    2013-09-01

    Full Text Available The rapid prototyping of millimeter wave (MMW multi-chip module (MCM on low-cost ceramic-polymer composite substrate using laser ablation process is presented. A Ka band MCM front-end receiver is designed, fabricated and tested. The complete front-end receiver module except the IF and power distribution sections is realized on the single prescribed substrate. The measured receiver gain, noise figure and image rejection is 37 dB, 4.25 dB and 40 dB respectively. However, it deduced from the experimental results of the two front-end modules that the complex permittivity characteristics of the substrate are altered after the laser ablation process. The effective permittivity alteration phenomenon is further validated through the characterization and comparison of various laser ablated and chemically etched Ka band parallel-coupled band-pass filters. A simple and experimentally verified method is worked out to utilize the laser ablation structuring process on the prescribed substrate. It is anticipated that the proposed method can be applied to other laminated substrates as well with the prescribed manufacturing process.

  20. Topography and Vegetation Characterization using Dual-Wavelength Airborne Lidar

    Science.gov (United States)

    Neuenschwander, A. L.; Bradford, B.; Magruder, L. A.

    2014-12-01

    Monitoring Earth surface dynamics at an ever increasing resolution has helped to support the characterization of local topography, including vegetated and urban environments. Airborne remote sensing using light detection and ranging (LIDAR) is naturally suited to characterize vegetation and landscapes as it provides detailed three-dimensional spatial data with multiple elevation recordings for each laser pulse. The full waveform LIDAR receiver is unique in this aspect as it can capture and record the complete temporal history of the reflected signal, which contains detailed information about the structure of the objects and ground surfaces illuminated by the beam. This study examines the utility of co-collected, dual-wavelength, full waveform LIDAR data to characterize vegetation and landscapes through the extraction of waveform features, including total waveform energy, canopy energy distribution, and foliage penetration metrics. Assessments are performed using data collected in May 2014 over Monterey, CA, including the Naval Postgraduate School campus area as well as the Point Lobos State Natural Reserve situated on the Monterey coast. The surveys were performed with the Chiroptera dual-laser LIDAR mapping system from Airborne Hydrography AB (AHAB), which can collect both green (515nm) and near infrared (1064nm) waveforms simultaneously. Making use of the dual waveforms allows for detailed characterization of the vegetation and landscape not previously possible with airborne LIDAR.

  1. Deep Space Ka-band Link Management and the MRO Demonstration: Long-term Weather Statistics Versus Forecasting

    Science.gov (United States)

    Davarian, Faramaz; Shambayati, Shervin; Slobin, Stephen

    2004-01-01

    During the last 40 years, deep space radio communication systems have experienced a move toward shorter wavelengths. In the 1960s a transition from L- to S-band occurred which was followed by a transition from S- to X-band in the 1970s. Both these transitions provided deep space links with wider bandwidths and improved radio metrics capability. Now, in the 2000s, a new change is taking place, namely a move to the Ka-band region of the radio frequency spectrum. Ka-band will soon replace X-band as the frequency of choice for deep space communications providing ample spectrum for the high data rate requirements of future missions. The low-noise receivers of deep space networks have a great need for link management techniques that can mitigate weather effects. In this paper, three approaches for managing Ka-band Earth-space links are investigated. The first approach uses aggregate annual statistics, the second one uses monthly statistics, and the third is based on the short-term forecasting of the local weather. An example of weather forecasting for Ka-band link performance prediction is presented. Furthermore, spacecraft commanding schemes suitable for Ka-band link management are investigated. Theses schemes will be demonstrated using NASA's Mars Reconnaissance Orbiter (MRO) spacecraft in the 2007 to 2008 time period, and the demonstration findings will be reported in a future publication.

  2. Thermal Deformation and RF Performance Analyses for the SWOT Large Deployable Ka-Band Reflectarray

    Science.gov (United States)

    Fang, H.; Sunada, E.; Chaubell, J.; Esteban-Fernandez, D.; Thomson, M.; Nicaise, F.

    2010-01-01

    A large deployable antenna technology for the NASA Surface Water and Ocean Topography (SWOT) Mission is currently being developed by JPL in response to NRC Earth Science Tier 2 Decadal Survey recommendations. This technology is required to enable the SWOT mission due to the fact that no currently available antenna is capable of meeting SWOT's demanding Ka-Band remote sensing requirements. One of the key aspects of this antenna development is to minimize the effect of the on-orbit thermal distortion to the antenna RF performance. An analysis process which includes: 1) the on-orbit thermal analysis to obtain the temperature distribution; 2) structural deformation analysis to get the geometry of the antenna surface; and 3) the RF performance with the given deformed antenna surface has been developed to accommodate the development of this antenna technology. The detailed analysis process and some analysis results will be presented and discussed by this paper.

  3. Analysis of a Novel Ka-band Folded Waveguide Amplifier for Traveling-Wave Tubes

    Institute of Scientific and Technical Information of China (English)

    LIAO Ming-Liang; WEI Yan-Yu; HE Jun; GONG Yu-Bin; WANG Wen-Xiang; Gun-Sik Park

    2009-01-01

    A novel Ka-band folded waveguide (FW) amplifier for traveling wave tubes (TWT) is investigated. The dispersion curve and interaction impedance are obtained and compared to the normal FW circuit by numerical simulation. The interaction impedance is higher than a normal circuit through the whole band. We also study the beam-wave interaction in this novel circuit, and the nonlinear large-signal performance is analyzed by a 3-D particle-in-cell code MACIC3D. A much higher continuous-wave (CW) output power with a considerably shorter circuit compared to a normal circuit is predicted by our simulation. Moreover, the novel FW even has a broader 3-dB bandwidth. It therefore will be useful in designing a miniature but high-power and broadband millimeter-wave TWT.

  4. Performance Analyses of the Radio Orbital Angular Momentum Steering Technique Based on Ka-Band Antenna

    Directory of Open Access Journals (Sweden)

    Mingtuan Lin

    2017-01-01

    Full Text Available The misalignment in the orbital angular momentum- (OAM- based system would distort the radiation patterns of twisted beams carrying OAM, consequently making the OAM-based communication infeasible. To tackle the misalignment problem, a radio OAM steering technique based on a uniform circular array (UCA is illustrated. Subsequently, simulations are conducted to explore the influence of the OAM steering on the OAM mode quality and transmission performance. Furthermore, UCAs working at Ka-band with formulated feeding networks are designed and fabricated to analyze the performance of the OAM steering. The influences of OAM steering on mode quality and orthogonality are then evaluated in the experiment. Overall, the analyses of OAM steering technique are beneficial for the development of radio OAM study.

  5. Thermal Deformation and RF Performance Analyses for the SWOT Large Deployable Ka-Band Reflectarray

    Science.gov (United States)

    Fang, H.; Sunada, E.; Chaubell, J.; Esteban-Fernandez, D.; Thomson, M.; Nicaise, F.

    2010-01-01

    A large deployable antenna technology for the NASA Surface Water and Ocean Topography (SWOT) Mission is currently being developed by JPL in response to NRC Earth Science Tier 2 Decadal Survey recommendations. This technology is required to enable the SWOT mission due to the fact that no currently available antenna is capable of meeting SWOT's demanding Ka-Band remote sensing requirements. One of the key aspects of this antenna development is to minimize the effect of the on-orbit thermal distortion to the antenna RF performance. An analysis process which includes: 1) the on-orbit thermal analysis to obtain the temperature distribution; 2) structural deformation analysis to get the geometry of the antenna surface; and 3) the RF performance with the given deformed antenna surface has been developed to accommodate the development of this antenna technology. The detailed analysis process and some analysis results will be presented and discussed by this paper.

  6. Enhancing End-to-End Performance of Information Services Over Ka-Band Global Satellite Networks

    Science.gov (United States)

    Bhasin, Kul B.; Glover, Daniel R.; Ivancic, William D.; vonDeak, Thomas C.

    1997-01-01

    The Internet has been growing at a rapid rate as the key medium to provide information services such as e-mail, WWW and multimedia etc., however its global reach is limited. Ka-band communication satellite networks are being developed to increase the accessibility of information services via the Internet at global scale. There is need to assess satellite networks in their ability to provide these services and interconnect seamlessly with existing and proposed terrestrial telecommunication networks. In this paper the significant issues and requirements in providing end-to-end high performance for the delivery of information services over satellite networks based on various layers in the OSI reference model are identified. Key experiments have been performed to evaluate the performance of digital video and Internet over satellite-like testbeds. The results of the early developments in ATM and TCP protocols over satellite networks are summarized.

  7. Ka-Band SiGe Receiver Front-End MMIC for Transponder Applications

    Science.gov (United States)

    Venkatesan, Jaikrishna; Mysoor, Narayan R.; Hashemi, Hassein; Aflatouni, Firooz

    2010-01-01

    A fully integrated, front-end Ka-band monolithic microwave integrated circuit (MMIC) was developed that houses an LNA (low noise amplifier) stage, a down-conversion stage, and output buffer amplifiers. The MMIC design employs a two-step quadrature down-conversion architecture, illustrated in the figure, which results in improved quality of the down-converted IF quadrature signals. This is due to the improved sensitivity of this architecture to amplitude and phase mismatches in the quadrature down-conversion process. Current sharing results in reduced power consumption, while 3D-coupled inductors reduce the chip area. Improved noise figure is expected over previous SiGe-based, frontend designs

  8. Cryo-Cooled Sapphire Oscillator for the Cassini Ka-Band Experiment

    Science.gov (United States)

    Wang, Rabi T.; Dick, G. John

    1997-01-01

    We present features for an ultra-stable sapphire cryogenic oscillator which has been designed to support the Cassini Ka-band Radio Science experiment. The design of this standard is new in several respects. It is cooled by a commercial cryocooler instead of liquid cryogens to increase operating time, and it uses a technology to adjust the temperature turn-over point to extend the upper operating temperature limit and to enable construction of multiple units with uniform operating characteristics. Objectives are 3 x 10(exp -15) stability for measuring times 1 second less than or equal to (tau) less than or equal to 100 seconds, phase noise of -85 dBc/Hz from offset frequencies of 1 Hz to 1000 Hz at 10 GHz carrier frequency, and a one year continuous operating period.

  9. Low phase noise GaAs HBT VCO in Ka-band

    Science.gov (United States)

    Ting, Yan; Yuming, Zhang; Hongliang, Lü; Yimen, Zhang; Yue, Wu; Yifeng, Liu

    2015-02-01

    Design and fabrication of a Ka-band voltage-controlled oscillator (VCO) using commercially available 1-μm GaAs heterojunction bipolar transistor technology is presented. A fully differential common-emitter configuration with a symmetric capacitance with a symmetric inductance tank structure is employed to reduce the phase noise of the VCO, and a novel π-feedback network is applied to compensate for the 180° phase shift. The on-wafer test shows that the VCO exhibits a phase noise of -96.47 dBc/Hz at a 1 MHz offset and presents a tuning range from 28.312 to 28.695 GHz. The overall dc current consumption of the VCO is 18 mA with a supply voltage of -6 V The chip area of the VCO is 0.7 × 0.7 mm2.

  10. Design of a Cryocooled Sapphire Oscillator for the Cassini Ka-Band Experiment

    Science.gov (United States)

    Dick, G. J.; Wang, R. T.

    1998-04-01

    We present design aspects of a cryogenic sapphire oscillator that is being developed for ultra-high short-term stability and low phase noise in support of the Cassini Ka-band (32-GHz) radio science experiment. With cooling provided by a commercial cryocooler instead of liquid helium, this standard is designed to operate continuously for periods of a year or more. Performance targets are a stability of 3 x 10^(-15) (1 second ≤ τ ≤ 100 seconds) and a phase noise of -73 dBc/Hz at 1 Hz measured at 34 GHz. Test results are reported for several subsystems, including the cryocooler, vibration isolation system, and ruby compensating element.

  11. Radiating Elements for Shared Aperture Tx/Rx Phased Arrays at K/Ka Band

    KAUST Repository

    Sandhu, A.I.

    2016-04-11

    A dual band, Tx/Rx, self-diplexing phased array is presented. The antenna has been designed to cover Tx/Rx satellite communications at K/Ka band with a frequency ratio 1.5:1. To obtain dual band operations with a single radiating surface, a novel dual band radiator is adopted and placed in a configuration in which dual band and single band elements are interleaved. The proposed configuration reduces the number of radiating elements required by other solutions while avoiding the insurgence of grating lobes. The tightly packed arrangement of the elements poses many integration issues, which are solved with a novel integration technique. The array elements are optimized to scan the beam in excess of ° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

  12. High-Efficiency Ka-Band Waveguide Two-Way Asymmetric Power Combiner

    Science.gov (United States)

    Wintucky, E. G.; Simons, R. N.; Freeman, J. C.; Chevalier, C. T.

    2011-01-01

    NASA is planning a number of Space Exploration, Earth Observation and Space Science missions where Ka-band solid-state power amplifiers (SSPAs) could have a role. Monolithic microwave integrated circuit (MMIC) based SSPAs with output powers on the order of 10 W at Ka-band frequencies would be adequate to satisfy the data transmission rate requirements at the distances involved. MMICs are a type of integrated circuit fabricated on a GaAs wafer, which operates at micro wave frequencies and performs the function of signal amplification. The highest power Ka-band (31.8 to 32.3 GHz) SSPA to have flown in space had an output power of 2.6 W with an overall efficiency of 14.3 percent. This SSPA was built around discrete GaAs pHEMT (high electron mobility transistor) devices and flew aboard the Deep Space One spacecraft. State-of-the-art GaAs pHEMT-based MMIC power amplifiers (PAs) can deliver RF power at Ka-band frequencies anywhere from 3 W with a power added efficiency (PAE) of 32 percent to 6 W with a PAE of 26 percent. However, to achieve power levels higher than 6 W, the output of several MMIC PAs would need to be combined using a high-efficiency power combiner. Conventional binary waveguide power combiners, based on short-slot and magic-T circuits, require MMIC PAs with identical amplitude and phase characteristics for high combining efficiency. However, due to manufacturing process variations, the output powers of the MMIC PAs tend to be unequal, and hence the need to develop unequal power combiners. A two-way asymmetric magic-T based power combiner for MMIC power amplifiers, which can take in unequal inputs, has been successfully designed, fabricated, and characterized over NASA s Deep Space Network (DSN) frequency range of 31.8 to 32.3 GHz. The figure is a transparent view of the a sym - metric combiner that shows the 4-port configuration and the internal structure. The rod, post, and iris are positioned by design to achieve the desired asymmetric power ratio

  13. High Efficiency Ka-Band Solid State Power Amplifier Waveguide Power Combiner

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.; Chevalier, Christine T.; Freeman, Jon C.

    2010-01-01

    A novel Ka-band high efficiency asymmetric waveguide four-port combiner for coherent combining of two Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifiers (SSPAs) having unequal outputs has been successfully designed, fabricated and characterized over the NASA deep space frequency band from 31.8 to 32.3 GHz. The measured combiner efficiency is greater than 90 percent, the return loss greater than 18 dB and input port isolation greater than 22 dB. The manufactured combiner was designed for an input power ratio of 2:1 but can be custom designed for any arbitrary power ratio. Applications considered are NASA s space communications systems needing 6 to 10 W of radio frequency (RF) power. This Technical Memorandum (TM) is an expanded version of the article recently published in Institute of Engineering and Technology (IET) Electronics Letters.

  14. Simultaneous Ka-Band Site Characterization: Goldstone, CA, White Sands, NM, and Guam, USA

    Science.gov (United States)

    Acosta, Roberto; Morse, Jacquelynne; Zemba, Michael; Nessel, James; Morabito, David; Caroglanian, Armen

    2011-01-01

    To statistically characterize atmospheric effects on Ka-band links at NASA operational sites, NASA has constructed site test interferometers (STI s) which directly measure the tropospheric phase stability and rain attenuation. These instruments observe an unmodulated beacon signal broadcast from a geostationary satellite (e.g., Anik F2) and measure the phase difference between the signals received by the two antennas and its signal attenuation. Three STI s have been deployed so far: the first one at the NASA Deep Space Network Tracking Complex in Goldstone, California (May 2007); the second at the NASA White Sands Complex, in Las Cruses, New Mexico (February 2009); and the third at the NASA Tracking and Data Relay Satellite (TDRS) Remote Ground Terminal (GRGT) complex in Guam (May 2010). Two station-years of simultaneous atmospheric phase fluctuation data have been collected at Goldstone and White Sands, while one year of data has been collected in Guam. With identical instruments operating simultaneously, we can directly compare the phase stability and rain attenuation at the three sites. Phase stability is analyzed statistically in terms of the root-mean-square (rms) of the tropospheric induced time delay fluctuations over 10 minute blocks. For two years, the time delay fluctuations at the DSN site in Goldstone, CA, have been better than 2.5 picoseconds (ps) for 90% of the time (with reference to zenith), meanwhile at the White Sands, New Mexico site, the time delay fluctuations have been better than 2.2 ps with reference to zenith) for 90% of time. For Guam, the time delay fluctuations have been better than 12 ps (reference to zenith) at 90% of the time, the higher fluctuations are as expected from a high humidity tropical rain zone. This type of data analysis, as well as many other site quality characteristics (e.g., rain attenuation, infrastructure, etc.) will be used to determine the suitability of all the sites for NASA s future communication services at Ka-band.

  15. Improvement of Ka-band satellite link availability for real-time IP-based video contribution

    Directory of Open Access Journals (Sweden)

    G. Berretta

    2017-09-01

    Full Text Available New High Throughput Satellite (HTS systems allow high throughput IP uplinks/contribution at Ka-band frequencies for relatively lower costs when compared to broadcasting satellite uplinks at Ku band. This technology offers an advantage for live video contribution from remote areas, where the terrestrial infrastructure may not be adequate. On the other hand, the Ka-band is more subject to impairments due to rain or bad weather. This paper addresses the target system specification and provides an optimized approach for the transmission of IP-based video flows through HTS commercial services operating at Ka-band frequencies. In particular, the focus of this study is on the service requirements and the propagation analysis that provide a reference architecture to improve the overall link availability. The approach proposed herein leads to the introduction of a new concept of live service contribution using pairs of small satellite antennas and cheap satellite terminals.

  16. Optical frequency combs generated by four-wave mixing in a dual wavelength Brillouin laser cavity

    Directory of Open Access Journals (Sweden)

    Qing Li

    2017-07-01

    Full Text Available We propose and demonstrate the generation of optical frequency combs via four-wave mixing in a dual wavelength Brillouin laser cavity. When pumped by two continuous-wave lasers with a varied frequency separation, dual wavelength Brillouin lasers with reduced linewidth and improved optical signal to noise ratios are generated in a direction opposite to the pump laser. Simultaneously, cavity-enhanced cascaded four-wave mixing between dual wavelength Brillouin lasers occurs in the laser cavity, causing the generation of broadband optical frequency combs with step tunable mode spacing from 40 to 1300 GHz. Compared to the cavity-less case, the number of the comb lines generated in the dual wavelength Brillouin laser cavity is increased by ∼38 times.

  17. Harnessing spectral property of dual wavelength white LED to improve vertical scanning interferometry.

    Science.gov (United States)

    Chong, Wee Keat; Li, Xiang; Soh, Yeng Chai

    2013-07-01

    Unlike a conventional white light source that emits a continuous and broad spectrum of light, the dual wavelength white light emitting diode (LED) generates white light by mixing blue and yellow lights, so there are two distinct peaks in its intensity spectrum. Prior works had shown that the spectral property of the dual wavelength white LED can affect the vertical scanning interferometry negatively if the spectral effects are not compensated. In this paper, we shall examine this issue by modeling the spectral property and variation of the dual wavelength white LED, followed by investigating its effects on the interference signal of vertical scanning interferometry. Instead of compensating the spectral effects of the dual wavelength white LED, we harness its spectral property to improve the performance of a phase-based height reconstruction algorithm in vertical scanning interferometry.

  18. A New Blind Pointing Model Improves Large Reflector Antennas Precision Pointing at Ka-Band (32 GHz)

    Science.gov (United States)

    Rochblatt, David J.

    2009-01-01

    The National Aeronautics and Space Administration (NASA), Jet Propulsion Laboratory (JPL)-Deep Space Network (DSN) subnet of 34-m Beam Waveguide (BWG) Antennas was recently upgraded with Ka-Band (32-GHz) frequency feeds for space research and communication. For normal telemetry tracking a Ka-Band monopulse system is used, which typically yields 1.6-mdeg mean radial error (MRE) pointing accuracy on the 34-m diameter antennas. However, for the monopulse to be able to acquire and lock, for special radio science applications where monopulse cannot be used, or as a back-up for the monopulse, high-precision open-loop blind pointing is required. This paper describes a new 4th order pointing model and calibration technique, which was developed and applied to the DSN 34-m BWG antennas yielding 1.8 to 3.0-mdeg MRE pointing accuracy and amplitude stability of 0.2 dB, at Ka-Band, and successfully used for the CASSINI spacecraft occultation experiment at Saturn and Titan. In addition, the new 4th order pointing model was used during a telemetry experiment at Ka-Band (32 GHz) utilizing the Mars Reconnaissance Orbiter (MRO) spacecraft while at a distance of 0.225 astronomical units (AU) from Earth and communicating with a DSN 34-m BWG antenna at a record high rate of 6-megabits per second (Mb/s).

  19. Design and Analysis of a 34 dBm Ka-Band GaN High Power Amplifier MMIC

    NARCIS (Netherlands)

    Heijningen, M. van; Vliet, F.E. van; Quay, R.; Raay, F. van; Seelmann-Eggebert, M.

    2006-01-01

    This paper presents the design and analysis issues related to the use of recent GaN technologies for realizing high power millimeter wave MMICs. Two GaN Ka-band amplifier MMICs have been designed, fabricated and characterized. The small-signal and power measurement results are presented for both amp

  20. Robust AlGaN/GaN low noise amplifier MMICs for C-, Ku- and Ka-band space applications

    NARCIS (Netherlands)

    Suijker, E.M.; Rodenburg, M.; Hoogland, J.A.; Heijningen, M. van; Seelmann-Eggebert, M.; Quay, R.; Brückner, P.; Vliet, F.E. van

    2009-01-01

    The high power capabilities in combination with the low noise performance of Gallium Nitride (GaN) makes this technology an excellent choice for robust receivers. This paper presents the design and measured results of three different LNAs, which operate in C-, Ku-, and Ka-band. The designs are reali

  1. Ka-Band Slot-Microstrip-Covered and Waveguide-Cavity-Backed Monopulse Antenna Array

    Directory of Open Access Journals (Sweden)

    Li-Ming Si

    2014-01-01

    Full Text Available A slot-microstrip-covered and waveguide-cavity-backed monopulse antenna array is proposed for high-resolution tracking applications at Ka-band. The monopulse antenna array is designed with a microstrip with 2×32 slots, a waveguide cavity, and a waveguide monopulse comparator, to make the structure simple, reduce the feeding network loss, and increase the frequency bandwidth. The 2×32 slot-microstrip elements are formed by a metal clad dielectric substrate and slots etched in the metal using the standard printed circuit board (PCB process with dimensions of 230 mm  ×  10 mm. The proposed monopulse antenna array not only maintains the advantages of the traditional waveguide slot antenna array, but also has the characteristics of wide bandwidth, high consistence, easy of fabrication, and low cost. From the measured results, it exhibits good monopulse characteristics, including the following: the maximum gains of sum pattern are greater than 24 dB, the 3 dB beamwidth of sum pattern is about 2.2 degrees, the sidelobe levels of the sum pattern are less than −18 dB, and the null depths of the difference pattern are less than −25 dB within the operating bandwidth between 33.65 GHz and 34.35 GHz for VSWR ≤ 2.

  2. User RF requirements for a Ka-band data relay satellite link

    Science.gov (United States)

    Copeland, David J.; Aleman, Roberto M.

    1989-01-01

    The user G/T and EIRP requirements were determined for a data relay satellite link consisting of a forward link to 360 Mbps at 23 GHz and a return link to 2 Gbps at 26.5 GHz. Hardware for this data link would be a modular expansion to the NASA Data Link Module. Calculations were based on a data relay satellite model of predetermined characteristics patterned after the NASA Tracking and Data Relay Satellite (TDRS). The desired data rates could be achieved with a G/T of 21.7 dB/deg K (forward link) and an EIRP of 68.2 dBW (return link) for the user satellite. Hardware configurations meeting these requirements are discussed in terms of RF performance, efficiency, reliability, and modular flexibility. A planar array configuration emerges as the logical candidate for most NASA missions. Pertinent Ka-band technology and certain ongoing research efforts are reviewed. Areas of particular interest include new power device families, 0.25-micron low-noise HEMT technology, and fiber optic distribution and control of RF arrays.

  3. Investigations of morphological features of picosecond dual-wavelength laser ablation of stainless steel

    Science.gov (United States)

    Zhao, Wanqin; Wang, Wenjun; Mei, Xuesong; Jiang, Gedong; Liu, Bin

    2014-06-01

    Investigations on the morphological features of holes and grooves ablated on the surface of stainless steel using the picosecond dual-wavelength laser system with different powers combinations are presented based on the scarce researches on morphology of dual-wavelength laser ablation. The experimental results show the profiles of holes ablated by the visible beam appear V-shaped while those for the near-infrared have large openings and display U-shaped, which are independent of the ablation mechanism of ultrafast laser. For the dual-wavelength beam (a combination of visible beam and near-infrared), the holes resemble sunflower-like structures and have smoother ring patterns on the bottom. In general, the holes ablated by the dual-wavelength beam appear to have much flatter bottoms, linearly sloped side-walls and spinodal structures between the bottoms of the holes and the side-walls. Furthermore, through judiciously combining the powers of the dual-wavelength beam, high-quality grooves could be obtained with a flat worm-like structure at the bottom surface and less resolidified melt ejection edges. This study provides insight into optimizing ultrafast laser micromachining in order to obtain desired morphology.

  4. Dual-wavelength distributed Bragg reflector semiconductor laser based on a composite resonant cavity

    Science.gov (United States)

    Chen, Cheng; Zhao, Ling-Juan; Qiu, Ji-Fang; Liu, Yang; Wang, Wei; Lou, Cai-Yun

    2012-09-01

    We report a monolithic integrated dual-wavelength laser diode based on a distributed Bragg reflector (DBR) composite resonant cavity. The device consists of three sections, a DBR grating section, a passive phase section, and an active gain section. The gain section facet is cleaved to work as a laser cavity mirror. The other laser mirror is the DBR grating, which also functions as a wavelength filter and can control the number of wavelengths involved in the laser action. The reflection bandwidth of the DBR grating is fabricated to have an appropriate value to make the device work at the dual-wavelength lasing state. We adopt the quantum well intermixing (QWI) technique to provide low-absorption loss grating and passive phase section in the fabrication process. By tuning the injection currents on the DBR and the gain sections, the device can generate 0.596 nm-spaced dual-wavelength lasing at room temperature.

  5. Stable dual-wavelength laser combined with gain flattening ML-FMF Bragg grating filter

    Science.gov (United States)

    Liang, Xiao; Li, Yang; Bai, Yunlong; Yin, Bin; Liu, Zhibo; Jian, Shuisheng

    2016-01-01

    A stable dual-wavelength laser combined with gain flattening multi-layer few-mode fiber Bragg grating filter was proposed and experimentally demonstrated. The index profile of the multi-layer few-mode fiber was particularly designed to support LP01 and LP11 modes with approximately equal excitation coefficients. And conventional phase-mask fabrication technique was used to inscribe Bragg gratings in the multi-layer few-mode fiber core, which leads to the gain flattening filter. A switchable dual-wavelength laser combined with the gain flattening filter was successfully achieved with simple linear configuration. The lasing wavelengths spacing was 0.39 nm. The variation of the central wavelength and intensity fluctuation were as small as 0.01 nm and <0.7 dBm in both dual-wavelength and single-wavelength operation regions, respectively.

  6. Dual wavelength erbium-doped fiber laser with a lateral pressure-tuned Hi-Bi fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Lingyun Xiong(熊凌云); Guiyun Kai(开桂云); Lei Sun(孙磊); Xinhuan Feng(冯新焕); Chunxian Xiao(肖纯贤); Yange Liu(刘艳格); Shuzhong Yuan(袁树忠); Xiaoyi Dong(董孝义)

    2004-01-01

    Tunable dual wavelength erbium-doped fiber laser (EDFL) with stable oscillation at room temperature is proposed and demonstrated. This laser utilizes a Bragg grating fabricated in a high birefringence fiber as the wavelength-selective component, and then achieves the stable dual wavelength oscillation by introducing the polarization hole burning effect. Furthermore, by applying lateral strain upon the fiber Bragg grating (FBG), the space of the laser dual wavelengths can be tuned continuously.

  7. AltiKa: a Ka-band Altimetry Payload and System for Operational Altimetry during the GMES Period

    Science.gov (United States)

    Vincent, Patrick; Steunou, Nathalie; Caubet, Eric; Phalippou, Laurent; Rey, Laurent; Thouvenot, Eric; Verron, Jacques

    2006-01-01

    This paper describes the Ka-band altimetry payload and system that has been studied for several years by CNES, ALCATEL SPACE and some science laboratories. Altimetry is one of the major elements of the ocean observing system to be made sustainable through the GEOSS (Global Earth Observation System of Systems) and GMES (Global Monitoring of the Environment and Security) programs. A short review of some mission objectives to be fulfilled in terms of mesoscale oceanography in the frame of the GEOSS and GMES programs is performed. To answer the corresponding requirements, the approach consisting in a constellation of nadir altimeter is discussed. A coupled Ka-band altimeter-radiometer payload is then described; technical items are detailed to explain how this payload shall meet the science and operational requirements, and expected performances are displayed. The current status of the payload development and flight perspectives are given.

  8. Frequency Tracking Performance Using a Hyperbolic Digital-Phase Locked Loop for Ka-Band Communication in Rain Fading Channels

    Science.gov (United States)

    Sithamparanathan, Kandeepan; Piesiewicz, Radoslaw

    In this paper we study and present some results on the performances of frequency tracking for Ka-band satellite communications in rain fading channels. The carrier frequency is tracked using a 2nd order hyperbolic phase detector based digital-phase locked loop (D-PLL). The hyperbolic D-PLL has the capability of extending the tracking range compared to the other D-PLL and hence can be designed such that to achieve low phase jitter performance for improved carrier tracking. We present the design and analysis of the D-PLL and show some simulation results on the frequency tracking performance for Ka-band rain fading channel. The results are compared with the non-fading noise only case and comparative analyses are made.

  9. Switchable and spacing-tunable dual-wavelength erbium-doped fibre lasers

    Institute of Scientific and Technical Information of China (English)

    Feng Xin-Huan; Liu Yan-Ge; Sun Lei; Yuan Shu-Zhong; Kai Gui-Yun; Dong Xiao-Yi

    2005-01-01

    Two switchable and spacing-tunable dual-wavelength linear cavity erbium-doped fibre lasers are demonstrated experimentally. One of them utilizes a Bragg grating in polarization-maintained PANDA fibre and the other uses a Bragg grating in standard single mode fibre for wavelength selection. Both exploit the birefringence characteristics of the FBG induced by transverse strain. The proposed lasers can be made to operate in stable dual-wavelength or switch between two wavelengths at room temperature just by simple adjustment of a polarization controller. Transverse strain loading on the FBG allows the wavelength spacing to be controlled.

  10. Stable dual-wavelength microlaser controlled by the output mirror tilt angle

    Science.gov (United States)

    Pallas, Florent; Herault, Emilie; Zhou, Jie; Roux, Jean-Francois; Vitrant, Guy

    2011-12-01

    A continuous-wave dual-wavelength solid-state microlaser is presented and a technique for regulating the gain competition between the two wavelengths is proposed, based on the angular tilt of the laser cavity output mirror. Laser behavior is studied and balanced dual-wavelength emission is obtained with output power levels as high as 200 mW for 2 W pump power. Sum frequency mixing is demonstrated making the source promising for Terahertz generation in the 0.5-0.7 THz range through difference frequency generation.

  11. High power dual-wavelength tunable fiber laser in linear and ring cavity configurations

    Institute of Scientific and Technical Information of China (English)

    H. Ahmad; A. A. Latif; M. Z. Zulkifli; N. A. Awang; S. W. Harun

    2012-01-01

    We describe and compare the performances of two crucial configurations for a tunable dual-wavelength fiber laser,namely,the linear and ring configurations.The performances of these two cavities and the tunability in the dual-wavelength output varied from 0.8 to 11.9 nm are characterized.The ring cavity provides a better performance,achieving an average output power of 0.5 dBm,with a power fluctuation of only 1.1 dB and a signal-to-noise ratio (SNR) of 66 dB.Moreover,the ring cavity has minimal or no background amplified spontaneous emission (ASE).

  12. Synchronization effects in a dual-wavelength class-B laser with modulated losses.

    Science.gov (United States)

    Kuntsevich, B F; Pisarchik, A N

    2001-10-01

    Different types of synchronization: in-phase, antiphase, phase, and lag synchronization, as well as amplitude death have been found theoretically in a dual-wavelength class-B laser with modulated losses in one of the channels. Depending on the laser parameters, oscillations in master and slave channels can be either completely or partially synchronized. The conditions for the dual-wavelength regime have been established. The analysis has been performed on the basis of transfer functions of the master and slave channels.

  13. Dual Wavelength High Power Double-Clad Ytterbium-Doped Fiber Laser

    Science.gov (United States)

    Moghaddam, M. R. A.; Harun, S. W.; Shahi, S.; Ahmad, H.

    A dual wavelength high power double-clad erbium/ytterbium-doped fiber laser with a narrowest spacing of 0.4 nm and a M2 value of close to unity is presented in the region of 1565 nm. This result can be realized with a significant improvement of the mode competition problem using a loop mirror as a comb filter. The wavelength region can also be varied using polarization controllers in the loop mirror. This dual-wavelength fiber laser with side mode suppression ratio (SMSR) of 40 dB is quite stable, and the output power variance is as low as 0.46 dB.

  14. DVB-RCS return link radio resource management for broadband satellite systems using fade mitigation techniques at ka band

    OpenAIRE

    2008-01-01

    Current Broadband Satellite systems supporting DVB-RCS at Ku band have static physical layer in order not to complicate their implementation. However at Ka band frequencies and above an adaptive physical layer wherein the physical layer parameters are dynamically modified on a per user basis is necessary to counteract atmospheric attenuation. Satellite Radio Resource Management (RRM) at the Medium Access Control (MAC) layer has become an important issue given the emphasis placed on Quality...

  15. Calibration of the KA Band Tracking of the Bepi-Colombo Spacecraft (more Experiment)

    Science.gov (United States)

    Barriot, J.; Serafini, J.; Sichoix, L.

    2013-12-01

    The radiosciences Bepi-Colombo MORE experiment will use X/X, X/Ka and Ka/Ka band radio links to make accurate measurements of the spacecraft range and range rate. Tropospheric zenith wet delays range from 1.5 cm to 10 cm, with high variability (less than 1000 s) and will impair these accurate measurements. Conditions vary from summer (worse) to winter (better), from day (worse) to night (better). These wet delays cannot be estimated from ground weather measurements and alternative calibration methods should be used in order to cope with the MORE requirements (no more than 3 mm at 1000 s). Due to the Mercury orbit, MORE measurements will be performed by daylight and more frequently in summer than in winter (from Northern hemisphere). Two systems have been considered to calibrate this wet delay: Water Vapor Radiometers (WVRs) and GPS receivers. The Jet Propulsion Laboratory has developed a new class of WVRs reaching a 5 percent accuracy for the wet delay calibration (0.75 mm to 5 mm), but these WVRs are expensive to build and operate. GPS receivers are also routinely used for the calibration of data from NASA Deep Space probes, but several studies have shown that GPS receivers can give good calibration (through wet delay mapping functions) for long time variations, but are not accurate enough for short time variations (100 to 1000 s), and that WVRs must be used to efficiently calibrate the wet troposphere delays over such time spans. We think that such a calibration could be done by assimilating data from all the GNSS constellations (GPS, GLONASS, Galileo, Beidou and IRNSS) that will be available at the time of the Bepi-Colombo arrival at Mercury (2021), provided that the underlying physics of the turbulent atmosphere and evapotranspiration processes are properly taken into account at such time scales. This implies to do a tomographic image of the troposphere overlying each Deep Space tracking station at time scales of less than 1000 s. For this purpose, we have

  16. Study of rain attenuation in Ka band for satellite communication in South Korea

    Science.gov (United States)

    Shrestha, Sujan; Choi, Dong-You

    2016-10-01

    The important factor to be considered in the link budget estimation for satellite communication systems, operating at frequencies above 10 GHz is the rain attenuation. Scattering and absorption are the main concern for system designers at these frequency bands. This has resulted in the need for suitable prediction models that can best provide estimates of attenuation due to rain with available information of rain attenuation data. Researchers have developed models that can be used to estimate 1-min rainfall attenuation distribution for earth space link but there is still some confusion with regard to choosing the right model to predict attenuation for the location of interest. In this context, the existing prediction models need to be tested against the measured results. This paper presents studies on rain attenuation at 19.8 GHz, which specifies the performance parameters for Ka-Band under earth space communication system. It presents the experimental result of rain rates and rain-induced attenuation in 19.8 and 20.73 GHz for vertical and circular polarization respectively. The received signal data for rain attenuation and rain rate were collected at 10 s intervals over a three year periods from 2013 to 2015. The data highlights the impact of clear air variation and rain fade loss. Rain rate data was measured through OTT Parsivel. During the observation period, rain rates of about 50 mm/h and attenuation values of 11.6 dB for 0.01% of the time were noted. The experimental link was set up at Korea Radio Promotion Association, Mokdong, Seoul. Out of several models, this paper present discussion and comparison of ITU-R P.618-12, Unified Method, Dissanayake Allnutt and Haidara (DAH), Simple Attenuation (SAM), Crane Global and Ramachandran and Kumar models. The relative error margin of 27.51, 89.84,72.46% and 67.24, 130.84, 166.48% are obtained for 0.1%, 0.01% and 0.001% of the time for 19.8 and 20.73 GHz under vertical and circular polarization respectively from ITU

  17. Ka-Band TWT High-Efficiency Power Combiner for High-Rate Data Transmission

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee; Vaden, Karl R.; Lesny, Gary G.; Glass, Jeffrey L.

    2007-01-01

    A four-port magic-T hybrid waveguide junction serves as the central component of a high-efficiency two-way power combiner circuit for transmitting a high-rate phase-modulated digital signal at a carrier frequency in the Ka-band (between 27 and 40 GHz). This power combiner was developed to satisfy a specific requirement to efficiently combine the coherent outputs of two traveling-wavetube (TWT) amplifiers that are typically characterized by power levels on the order of 100 W or more. In this application, the use of a waveguide-based power combiner (instead of a coaxial-cable- or microstrip-based power combiner, for example) is dictated by requirements for low loss, high power-handling capability, and broadband response. Combiner efficiencies were typically 90 percent or more over both the linear and saturated output power regions of operation of the TWTs . Figure 1 depicts the basic configuration of the magic-T hybrid junction. The coherent outputs of the two TWTs enter through ports 1 and 4. As a result of the orientations of the electromagnetic fields, which also provides a needed high port-to-port isolation, of these two input signals and the interior design of the magic-T junction, the input powers are divided so as to add in phase at one output port (port 2), and to be opposite in phase and hence cancel each other at the opposite coplanar output port (port 3). The net result is that the output power at port 2 is essentially double that of the output of one TWT, minus the power lost in the magic-T hybrid junction. Optimum performance as a high-efficiency power combiner thus requires a balance of both power and phase at the input ports of the magic-T. Replicas of this two-way combiner can be arranged in a binary configuration to obtain a 2n-way (where n is an integer) combiner. For example, Figure 2 illustrates the use of three two-way combiners to combine the outputs of four TWTs.

  18. Airborne Dual-Wavelength LiDAR Data for Classifying Land Cover

    Directory of Open Access Journals (Sweden)

    Cheng-Kai Wang

    2014-01-01

    Full Text Available This study demonstrated the potential of using dual-wavelength airborne light detection and ranging (LiDAR data to classify land cover. Dual-wavelength LiDAR data were acquired from two airborne LiDAR systems that emitted pulses of light in near-infrared (NIR and middle-infrared (MIR lasers. The major features of the LiDAR data, such as surface height, echo width, and dual-wavelength amplitude, were used to represent the characteristics of land cover. Based on the major features of land cover, a support vector machine was used to classify six types of suburban land cover: road and gravel, bare soil, low vegetation, high vegetation, roofs, and water bodies. Results show that using dual-wavelength LiDAR-derived information (e.g., amplitudes at NIR and MIR wavelengths could compensate for the limitations of using single-wavelength LiDAR information (i.e., poor discrimination of low vegetation when classifying land cover.

  19. Isotope analysis of water by means of near-infrared dual-wavelength diode laser spectroscopy

    NARCIS (Netherlands)

    Gianfrani, L.; Gagliardi, G.; Burgel, M. van; Kerstel, E.R.Th.; Gianfrani, I.; Galgiardi, G.

    2003-01-01

    A novel diode laser spectrometer was developed using dual-wavelength multiplexing, ensuring ideal conditions for high-precision and simultaneous measurements of the H-2/H-1, O-17/O-16, and O-18/O-16 isotope ratios in water. A 1.4-mum diode laser probed a (HOH)-O-16/(HOH)-H-2 line pair near 7198

  20. Analysis and Mitigation of Tropospheric Effects on Ka Band Satellite Signals and Estimation of Ergodic Capacity and Outage Probability for Terrestrial Links

    OpenAIRE

    Enserink, Scott Warren

    2012-01-01

    The first part of this work covers the effect of the troposphere onKa band (20-30 GHz) satellite signals. The second part deals withthe estimation of the capacity and outage probability forterrestrial links when constrained to quadrature amplitudemodulations.The desire for higher data rates and the need for availablebandwidth has pushed satellite communications into the Ka band(20-30 GHz). At these higher carrier frequencies the effects ofscintillation and rain attenuation are increased. In...

  1. Coherent summation of Ka-band microwave beams produced by sub-gigawatt superradiance backward wave oscillators

    Science.gov (United States)

    Sharypov, K. A.; El'chaninov, A. A.; Mesyats, G. A.; Pedos, M. S.; Romancheko, I. V.; Rostov, V. V.; Rukin, S. N.; Shpak, V. G.; Shunailov, S. A.; Ul'masculov, M. R.; Yalandin, M. I.

    2013-09-01

    Coherent summation of microwave beams has been demonstrated for two superradiance Ka-band backward wave oscillators producing over 700 MW of power. The explosive emission cathodes of the e-beam injectors were powered by stable splitted voltage pulses produced by an all-solid-state modulator. The voltage fronts were shortened to 300 ps in controlled delay shock-excited ferrite lines. The standard deviation of the phase difference between the microwave pulses was less than 2% of the oscillations period. The power flux density of the summarized radiation was the same as that of a single generator producing an output power of ˜3 GW.

  2. Low cost low phase noise PLL controlled push-push VCOs in k- and ka- bands, stabilized by cavity resonator

    OpenAIRE

    Tsvelykh, I. S.; B. A. Kotserzhynskyi

    2016-01-01

    This work demonstrates push-push VCOs in K-band (with second harmonic output at 24 GHz) and in Ka-band (with third harmonic output at 36 GHz), and PLL synthesizers on their basis. Oscillators are stabilized by a rectangular resonant metallic cavity. Output signal power within the frequency tuning range changes in the limits of -11,5 -7,6 dBm and -11,8 -10,9 dBm for 24 GHz and 36 GHz oscillators respectively. Single sideband (SSB) phase noise spectral densities of -91 dBc/Hz for 24 GHz oscilla...

  3. Phase Noise Enhancement of the GaAs High Electron Mobility Transistors Using Micromachined Cavity Resonators at Ka-band

    Science.gov (United States)

    Song, Insang; Kim, Chungwoo; Kwon, Youngwoo; Cheon, Changyul; Song, Cimoo

    1999-06-01

    We introduce a new structure of the micromachined cavity resonator coupled GaAs-based oscillator to enhance the phase noise and the frequency stability. The oscillator and the cavity are designed for Ka-band applications. Compared to the free running oscillator, the cavity resonator coupled oscillator showed the phase noise enhancement of about 20 dB. The phase noises of about -110 and -85 dBc/Hz are obtained at 1 MHz and 100 kHz offset frequency, respectively. The frequency pushing for the gate bias of the cavity coupled oscillator is about two order of magnitude less than that of the free running oscillator.

  4. A Novel Low-Cost Dual-Wavelength Precipitation Radar Sensor Network Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA is committed to measuring precipitation on a global scale. In 1997, NASA launched the Tropical Rain Measuring Mission which carried the first spaceborne...

  5. Orthogonally polarized dual-wavelength Yb:KGW laser induced by thermal lensing

    Science.gov (United States)

    Zhao, Haitao; Major, Arkady

    2016-06-01

    Simultaneous dual-wavelength laser oscillation with orthogonal polarizations has been observed and analyzed in a continuous wave N g-cut Yb:KGW oscillator. Without inserting any optical elements for polarization control, the N m- and N p-polarized modes, each of which possessed a distinct wavelength, coexisted and switched twice in two power regimes as the pump power was varied. The two wavelengths and their separation slightly depended on output coupling level. The wavelength switching and coexistence was studied and explained by considering the thermal and spectral anisotropy of the Yb:KGW crystals, which led to polarization-dependent reabsorption loss in the unpumped regions of the crystal. The maximum average output power obtained in the dual-wavelength regime was 4.6 W.

  6. Optical design of f-theta lens for dual wavelength selective laser melting

    Science.gov (United States)

    Feng, Lianhua; Cao, Hongzhong; Zhang, Ning; Xu, Xiping; Duan, Xuanming

    2016-10-01

    F-theta lens is an important unit for selective laser melting (SLM) manufacture. The dual wavelength f-theta lens has not been used in SLM manufacture. Here, we present the design of the f-theta lens which satisfies SLM manufacture with coaxial 532 nm and 1030 nm 1080 nm laser beams. It is composed of three pieces of spherical lenses. The focal spots for 532 nm laser and 1030 nm 1080 nm laser are smaller than 35 μm and 70 μm, respectively. The results meet the demands of high precision SLM. The chromatic aberration could cause separation between two laser focal spots in the scanning plane, so chromatic aberration correction is very important to our design. The lateral color of the designed f-theta lens is less than 11 μm within the scan area of 150 mm x 150 mm, which meet the application requirements of dual wavelength selective laser melting.

  7. Dual wavelength operation in diode-end-pumped hybrid vanadate laser

    Indian Academy of Sciences (India)

    A J Singh; S K Sharma; P K Mukhopadhyay; S M Oak

    2010-11-01

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition rate is obtained with 32 ns FWHM pulse duration corresponding to 25 kW of the peak power. The intensity and the polarization of the individual spectral components can be easily controlled by changing the relative gain and the relative orientation of the two crystals. The resulting pulsed dual-wavelength laser has the potential to be used as a source for generating terahertz radiation.

  8. Single- and dual-wavelength switchable linear polarized Yb(3+)-doped double-clad fiber laser.

    Science.gov (United States)

    Liu, Guanxiu; Feng, Dejun

    2015-05-10

    A single- and dual-wavelength switchable linear polarized Yb-doped double-clad fiber laser is proposed, in which the resonance cavity was composed of a fiber Bragg grating fabricated in a polarization-maintaining fiber and a dichromatic mirror with high reflectivity. The polarization hole burning is enhanced through selective polarization feedback by the polarization-maintaining fiber Bragg grating. The switchover of single and dual wavelengths is realized by tuning the rotation angle of a cubic polarization beam splitter that is inserted between the dichromatic mirror and the collimator in the cavity. The laser features wavelengths of 1070.08 and 1070.39 nm, output power of 1.0 W, signal to noise ratio of 45 dB, and slope efficiency of 34%, as well as a very narrow linewidth of 0.022 nm. The polarization characteristics are analyzed by measuring the laser power transmitted through a Glan-Thomson polarizer during rotation.

  9. Highly stable graphene-assisted tunable dual-wavelength erbium-doped fiber laser.

    Science.gov (United States)

    Ahmad, Harith; Latif, Amirah Abdul; Abdul Khudus, Muhammad Imran Mustafa; Zulkifli, Ahmad Zarif; Zulkifli, Mohd Zamani; Thambiratnam, Kavintheran; Harun, Sulaiman Wadi

    2013-02-01

    A highly stable tunable dual-wavelength fiber laser (TDWFL) using graphene as a means to generate a highly stable output is proposed and generated. The TDWFL comprises a 1 m long, highly doped erbium-doped fiber (EDF) acting as the linear gain medium, with a 24-channel arrayed waveguide grating acting as a wavelength slicer as well as a tuning mechanism to generate different wavelength pairs. The tuned wavelength pairs can range from 0.8 to 18.2 nm. A few layers of graphene are incorporated into the laser cavity to induce the four-wave-mixing effect, which stabilizes the dual-wavelength output by suppressing the mode competition that arises as a result of homogenous broadening in the EDF.

  10. Dual-wavelength stable nanosecond pulses generation from cladding-pumped fiber laser

    Institute of Scientific and Technical Information of China (English)

    Shuling Hu; Jing Yu; Chunqing Gao; Guanghui Wei; Fuyun Lü

    2006-01-01

    In this paper, the generation of dual-wavelength stable nanosecond pulses by a laser diode pumped Ybdoped double-clad fiber laser is presented. In the experiment, the fiber laser with two-mirror cavity is approved which operates in a self-Q-switching regime. The Q-switching mechanism is based on stimulatedBrillouin scattering (SBS). When the pump power achieves the SBS threshold, the fiber laser changes from the start resonator to the SBS resonator. With different reflectivities of the second mirror, stable dual-wavelength pulses with the pulse width range from 10 ns to less than 2 ns are obtained. The resultwas explained theoretically by birefringency (including stochastic birefringency and bend birefringency).

  11. Switchable dual-wavelength all-fiber laser mode-locked by carbon nanotubes

    Science.gov (United States)

    Kong, Y. C.; Yang, H. R.; Li, W. L.; Chen, G. W.

    2015-01-01

    We have proposed a compact dual-wavelength all-fiber pulse laser based on a single-walled carbon nanotube and chirped fiber Bragg gratings (CFBGs). A transmission filter is composed of a circulator and two CFBGs and is capable of controlling the operation of the proposed fiber laser. Mode-locking operations can be switched between 1551.2 and 1548.6 nm with the appropriate adjustment of polarization controller. Our laser delivers the pulses with the spectral bandwidth of about 0.6 nm and the pulse duration of about 7 ps. This work provides a low-cost, stable, and dual-wavelength ultrafast-pulsed laser source suitable for practical applications.

  12. Installing the earth station of Ka-band satellite frequency in Malaysia: conceptual framework for site decision

    Science.gov (United States)

    Mahmud, M. R.; Reba, M. N. M.; Jaw, S. W.; Arsyad, A.; Ibrahim, M. A. M.

    2017-05-01

    This paper developed a conceptual framework in determining the suitable location in installing the earth station for Ka-band satellite communication in Malaysia. This current evolution of high throughput satellites experienced major challenge due to Malaysian climate. Because Ka-band frequency is highly attenuated by the rainfall; it is an enormous challenge to define the most appropriate site for the static communication. Site diversity, a measure to anticipate this conflict by choosing less attenuated region and geographically change the transmission strategy on season basis require accurate spatio-temporal information on the geographical, environmental and hydro-climatology at local scale. Prior to that request, this study developed a conceptual framework to cater the needs. By using the digital spatial data, acquired from site measurement and remote sensing, the proposed framework applied a multiple criteria analysis to perform the tasks of site selection. With the advancement of high resolution remotely sensed data, site determination can be conducted as in Malaysia; accommodating a new, fast, and effective satellite communication. The output of this study is one of the pioneer contributions to create a high tech-society.

  13. Ka-Band Link Study and Analysis for a Mars Hybrid RF/Optical Software Defined Radio

    Science.gov (United States)

    Zeleznikar, Daniel J.; Nappier, Jennifer M.; Downey, Joseph A.

    2014-01-01

    The integrated radio and optical communications (iROC) project at the NASA Glenn Research Center (GRC) is investigating the feasibility of a hybrid RF and optical communication subsystem for future deep space missions. The hybrid communications subsystem enables the advancement of optical communications while simultaneously mitigating the risk of infusion by combining an experimental optical transmitter and telescope with a reliable Ka-band RF transmitter and antenna. The iROC communications subsystem seeks to maximize the total data return over the course of a potential 2-year mission in Mars orbit beginning in 2021. Although optical communication by itself offers potential for greater data return over RF, the reliable Ka-band link is also being designed for high data return capability in this hybrid system. A daily analysis of the RF link budget over the 2-year span is performed to optimize and provide detailed estimates of the RF data return. In particular, the bandwidth dependence of these data return estimates is analyzed for candidate waveforms. In this effort, a data return modeling tool was created to analyze candidate RF modulation and coding schemes with respect to their spectral efficiency, amplifier output power back-off, required digital to analog conversion (DAC) sampling rates, and support by ground receivers. A set of RF waveforms is recommended for use on the iROC platform.

  14. Dual-wavelength operation of a figure-eight fiber laser

    Science.gov (United States)

    Pottiez, O.; Hernandez-Garcia, J. C.; Ibarra-Escamilla, B.; Kuzin, E. A.

    2012-10-01

    We study numerically an erbium-doped figure-eight fiber laser including a double-band-pass optical filter for dual-wavelength pulse generation. Simulations are performed for several values of the filter band-width and wavelength separation between the transmission windows. The results show that dual-wavelength mode-locking is obtained in most cases, with a balanced energy distribution between wavelengths. Due to cavity dispersion, the pulses at each wavelength are asynchronous for a large wavelength separation, whereas they are synchronous for closely spaced wavelengths, as in this case cross-phase modulation is able to compensate for the dispersion-induced walkoff. In the asynchronous case, dual-wavelength operation is favored by the filter loss, whereas in the synchronous case it is favored by the saturable absorber action of the nonlinear optical loop mirror. Simulations also show that, thanks to those stabilization mechanisms, dual-wave-length pulsed operation does not require precise cavity loss equalization between the two oscillating wave-lengths.

  15. Study of dual wavelength composite output of solid state laser based on adjustment of resonator parameters

    Science.gov (United States)

    Wang, Lei; Nie, Jinsong; Wang, Xi; Hu, Yuze

    2016-10-01

    The 1064nm fundamental wave (FW) and the 532nm second harmonic wave (SHW) of Nd:YAG laser have been widely applied in many fields. In some military applications requiring interference in both visible and near-infrared spectrum range, the de-identification interference technology based on the dual wavelength composite output of FW and SHW offers an effective way of making the device or equipment miniaturized and low cost. In this paper, the application of 1064nm and 532nm dual-wavelength composite output technology in military electro-optical countermeasure is studied. A certain resonator configuration that can achieve composite laser output with high power, high beam quality and high repetition rate is proposed. Considering the thermal lens effect, the stability of this certain resonator is analyzed based on the theory of cavity transfer matrix. It shows that with the increase of thermal effect, the intracavity fundamental mode volume decreased, resulting the peak fluctuation of cavity stability parameter. To explore the impact the resonator parameters does to characteristics and output ratio of composite laser, the solid-state laser's dual-wavelength composite output models in both continuous and pulsed condition are established by theory of steady state equation and rate equation. Throughout theoretical simulation and analysis, the optimal KTP length and best FW transmissivity are obtained. The experiment is then carried out to verify the correctness of theoretical calculation result.

  16. Dual-wavelength dissipative soliton operation of an erbium-doped fibre laser using a nonlinear polarization rotation technique

    Institute of Scientific and Technical Information of China (English)

    Cao Wen-Jun; Xu Wen-Cheng; Luo Zhi-Chao; Wang Lu-Yan; Wang Hui-Yi; Dong Jiang-Li; Luo Ai-Ping

    2011-01-01

    We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation (NPR) technique.Taking the intrinsic advantage of the intracavity birefringence-induced spectral filtering effect in the NPR-based ring laser cavity,the dual-wavelength dissipative solitons are obtained.In addition,the wavelength separation and the lasing location of the dual-wavelength solitons can be flexibly tuned by changing the orientation of the polarization controller.

  17. Solid state Ka-band pulse oscillator with frequency electronic switching

    Directory of Open Access Journals (Sweden)

    Dvornichenko V. P.

    2015-08-01

    Full Text Available Transmitting devices for small radars in the millimeter wavelength range with high resolution on range and noise immunity. The work presents the results of research and development of compact pulse oscillators with digital frequency switching from pulse to pulse. The oscillator consists of a frequency synthesizer and a synchronized amplifier on the IMPATT diode. Reference oscillator of synthesizer is synchronized by crystal oscillator with digital PLL system and contains a frequency multiplier and an amplifier operating in pulse mode. Small-sized frequency synthesizer of 8 mm wave lengths provides an output power of ~1.2 W per pulse with a frequency stability of no worse than 2•10–6. Radiation frequency is controlled by three-digit binary code in OOL levels. Synchronized amplifier made on IMPATT diodes provides microwave power up to 20 W in oscillator output with microwave pulse duration of 100—300 ns in an operating band. The oscillator can be used as a driving source for the synchronization of semiconductor and electro-vacuum devices of pulsed mode, and also as a transmitting device for small-sized radar of millimeter wave range.

  18. Advanced multi-frequency radar: Design, preliminary measurements and particle size distribution retrieval

    Science.gov (United States)

    Majurec, Ninoslav

    In the spring of 2001 the Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts began the development of an advanced Multi-Frequency Radar (AMFR) system for studying clouds and precipitation. This mobile radar was designed to consist of three polarimetric Doppler subsystems operating at Ku-band (13.4 GHz), Ka-band (35.6 GHz) and W-band (94.92 GHz). This combination of frequency bands allows a measurement of a wide range of atmospheric targets ranging from weakly reflecting clouds to strong precipitation. The antenna beamwidths at each frequency were intentionally matched, ensuring consistent sampling volume. Multi-frequency radar remote sensing techniques are not widely used because few multi-frequency radars are available to the science community. One exception is the 33 GHz/95 GHz UMass Cloud Profiling Radar System (CPRS), which AMFR is intended to replace. AMFR's multi-parameter capabilities are designed for characterizing the complex microphysics of layer clouds and precipitation processes in winter storms. AMFR will also play an important role in developing algorithms and validating measurements for an upcoming generation of space-borne radars. The frequency bands selected for AMFR match those of several sensors that have been deployed or are under development. These include the Japanese Aerospace Exploration Agencies (JAXA's) Tropical Rainfall Measuring Mission (TRMM) satellite Ku-band (13 GHz) radar, the CloudSat W-band (95 GHz) radar, and the Global Precipitation Mission (GPM) satellite radars at Ku-band and Ka-band. This dissertation describes the AMFR hardware design and development. Compared to CPRS, the addition of one extra frequency band (Ku) will extend AMFR's measurement capabilities towards the larger particle sizes (precipitation). AMFR's design is based around high-power klystron amplifiers. This ensures complete coherency (CPRS uses magnetrons and coherent-on-receive technique). The partial loss in sensitivity due to

  19. Dual-wavelength eye-safe Nd:GYSGG/YVO4 intracavity Raman laser under in-band pumping

    Science.gov (United States)

    Jiang, P. B.; Sheng, Q.; Ding, X.; Sun, B.; Liu, J.; Zhao, C.; Zhang, G. Z.; Yu, X. Y.; Li, B.; Wu, L.; Yao, J. Q.

    2017-01-01

    An acousto-optic (AO) Q-switched dual-wavelength laser operating at 1.5 μm eye-safe region is demonstrated via stimulated Raman scatting of a-cut YVO4-Nd:YVO4 crystal within an end-pumped dual-wavelength Nd:GYSGG laser cavity. The in-band pumping absorption peak and coefficient of the dual-wavelength laser crystal Nd:GYSGG are measured in order to carry out efficient pumping, thus overcoming the drawbacks of short thermal focal length of the crystal and scale up the eye-safe output. Under 23.2 W absorbed pump power, 2.11 W of simultaneous dual-wavelength outputs at 1497 and 1516 nm are obtained with a pulse repetition rate of 23 kHz and a corresponding conversion efficiency of 9.1%.

  20. Synchronization of radiation in an oversized coaxial Ka-band backward wave oscillator using two-dimensional Bragg structure

    Directory of Open Access Journals (Sweden)

    N. S. Ginzburg

    2015-12-01

    Full Text Available A coaxial Ka-band backward wave oscillator with a two-dimensional Bragg structure located at the output of the interaction space has been studied. This structure has a double-period corrugation and provides azimuthal electromagnetic energy fluxes, which act on the synchronized radiation of an oversized tubular electron beam. Proof-of-principle experiments were conducted based on the Saturn thermionic accelerator (300  keV/200  A/2  μs. In accordance with simulations, narrow-band generation was obtained at a frequency of 30 GHz and a power level of 1.5–2 MW. As a result, the possibility of using a two-dimensional distributed feedback mechanism in oscillators of the Cherenkov type has been demonstrated.

  1. A comparison of MESFET and HEMT MMIC technologies using a compact Ka-band voltage-controlled oscillator

    Science.gov (United States)

    Swirhun, S.; Geddes, J.; Sokolov, Vladimir; Bosch, D.; Gawronski, M.; Anholt, R.

    1991-07-01

    To compare the capability of MESFET and HEMT technologies for monolithic microwave integrated circuit (MMIC) implementation we have fabricated and tested discrete field-effect transistors (FETs) and a novel Ka-band monolithic voltage controlled oscillator (VCO). We implemented the circuit with three different active devices: moderate- and high-doped ion-implanted MESFETs (metal-semiconductor FETs) and AlGaAs/GaAs HEMTs (high electron mobility transistors). A comparison of the measured oscillator phase-noise and an independent comparison of the temperature dependence of MESFET and HEMT RF equivalent circuits yields two general guidelines: MESFETs are preferred over HEMTs for applications requiring low phase-noise and temperature insensitive operation.

  2. A Ka-band monolithic low phase noise coplanar waveguide oscillator using InAlAs/InGaAs HBT

    Science.gov (United States)

    Cui, Delong; Hsu, Shawn; Pavlidis, Dimitris; Chin, Patrick; Block, Tom

    2002-02-01

    A Ka-band oscillator has been designed, fabricated and tested using InAlAs/InGaAs HBTs. Coplanar waveguide technology has been employed to improve the Q-factor of the circuit. An output power of 2.6 dBm with DC to RF conversion efficiency of 7.8% was measured at 31.7 GHz. Low phase noise of -87 and -112 dBc/Hz were achieved at an offset frequency of 100 kHz and 1 MHz respectively. These low phase noise values can be attributed to the low 1/ f noise of the InAlAs/InGaAs HBT devices and the coplanar design used for the circuit.

  3. Ka-band and X-band observations of the solar corona acquired during the Cassini 2001 superior conjunction

    Science.gov (United States)

    Morabito, D. D.

    2002-01-01

    Simultaneous dual-frequency Ka-band (32 GHz) and X-band (8.4 GHz) carrier signal data have been acquired during the superior conjunction of the Cassini spacecraft June 2001, using the NASA Deep Space Network's facilities located in Goldstone, California. The solar elongation angle of the observations varied from -4.1 degrees (-16 solar radii) to -0.6 degrees (-2.3 solar radii). The observed coronal and solar effects on the signals include spectral broadening, amplitude scintillation, phase scintillation, and increased noise. The measurements were generally consistent with existing solar models, except during solar transient events when the signatures of the measurements were observed to increase significantly above the quiet background levels. This is the second solar conjunction of Cassini for which simultaneous X/Ka data were acquired. Both solar conjunctions, conducted in May 2000 and June 2001, occurred near the peak of the current 11 year solar cycle.

  4. AltiKa: a Ka-band Altimetry Payload and System for Operational Altimetry during the GMES Period

    Directory of Open Access Journals (Sweden)

    Jacques Verron

    2006-03-01

    Full Text Available This paper describes the Ka-band altimetry payload and system that has beenstudied for several years by CNES, ALCATEL SPACE and some science laboratories.Altimetry is one of the major elements of the ocean observing system to be madesustainable through the GEOSS (Global Earth Observation System of Systems and GMES(Global Monitoring of the Environment and Security programs. A short review of somemission objectives to be fulfilled in terms of mesoscale oceanography in the frame of theGEOSS and GMES programs is performed. To answer the corresponding requirements, theapproach consisting in a constellation of nadir altimeter is discussed. A coupled Ka-bandaltimeter-radiometer payload is then described; technical items are detailed to explain howthis payload shall meet the science and operational requirements, and expectedperformances are displayed. The current status of the payload development and flightperspectives are given.

  5. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    Science.gov (United States)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-06-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  6. Design of an optically controlled Ka-band GaAs MMIC phased-array antenna

    Science.gov (United States)

    Kunath, Richard R.; Bhasin, Kul B.; Claspy, Paul C.; Richard, Mark A.

    1990-01-01

    Phased array antennas long were investigated to support the agile, multibeam radiating apertures with rapid reconfigurability needs of radar and communications. With the development of the Monolithic Microwave Integrated Circuit (MMIC), phased array antennas having the stated characteristics are becoming realizable. However, at K-band frequencies (20 to 40 GHz) and higher, the problem of controlling the MMICs using conventional techniques either severely limits the array size or becomes insurmountable due to the close spacing of the radiating elements necessary to achieve the desired antenna performance. Investigations were made that indicate using fiber optics as a transmission line for control information for the MMICs provides a potential solution. By adding an optical interface circuit to pre-existing MMIC designs, it is possible to take advantage of the small size, lightweight, mechanical flexibility and RFI/EMI resistant characteristics of fiber optics to distribute MMIC control signals. The architecture, circuit development, testing and integration of optically controlled K-band MMIC phased array antennas are described.

  7. In Vivo Detection of Rat Colorectal Cancers by using a Dual-Wavelength Excitation Method

    Science.gov (United States)

    Miyawaki, Kiichiro; Harada, Yoshinori; Wakabayashi, Naoki; Imaizumi, Katsuichi; Koizumi, Noriaki; Nakano, Keimei; Yamaoka, Yoshihisa; Dai, Ping; Itoh, Yoshito; Takamatsu, Tetsuro

    2014-01-01

    Hypoxia is a characteristic feature of solid neoplasms, and insufficient oxygen supply increases cellular nicotinamide adenine dinucleotide (NADH) fluorescence, which is a main component of autofluorescence of the colorectal mucosa. We investigated whether a dual-wavelength excitation method which is optimized for sensing mucosal NADH fluorescence could be applicable to the detection of rat colorectal cancers in vivo. Rat colorectal adenocarcinomas were studied by using fluorescence stereomicroscopy. After autofluorescence images at 470 nm irradiated with dual-wavelength excitation at 365 nm (F365ex) and 405 nm (F405ex) were acquired, ratio images were produced by dividing F365ex by F405ex: The excitation-emission wavelength pairs in F365ex and F405ex were adjusted for acquisition of NADH fluorescence and reference fluorescence. Based on observations from the luminal surface in vivo, F365ex/F405ex ratio images indicated a 1.57-fold higher signal value in the cancers than in the surrounding normal mucosa. The signal values in F365ex/F405ex ratio images were less mutually related with the hemoglobin concentration index. Small adenocarcinomas (less than 4 mm) could be detected on F365ex/F405ex ratio images. The results showed that NADH fluorescence measurement with little interference from tissue hemoglobin is efficient for visualizing rat colorectal cancers in vivo, suggesting that the dual-wavelength excitation method has potential for label-free endoscopic detection of diminutive colorectal neoplasms. PMID:25861131

  8. Tunable dual-wavelength filter and its group delay dispersion in domain-engineered lithium niobate

    Directory of Open Access Journals (Sweden)

    Guang-hao Shao

    2016-12-01

    Full Text Available A tunable dual-wavelength filter is experimentally demonstrated in domain-engineered lithium niobate. Application of an electric field on the y-surfaces of the sample results in the optical axes rotating clockwise and anticlockwise, which makes selective polarization rotation. The quasi phase-matching wavelengths could be adjusted through suitable domain design. A unique dual valley spectrum is obtained in a periodically poled lithium niobate structure with a central defect if the sample is placed between two parallel polarizers. The expected bandwidth could be varied from ∼1 nm to ∼40 nm. Moreover, both the spectral response and group delay dispersion could be engineered.

  9. Quality improvement of the dual-wavelength signals in DLOB via power equalization

    Institute of Scientific and Technical Information of China (English)

    TIAN Chang-yong; WU Chong-qing; SUN Guang-na; LI Xue; LI Zheng-yong

    2008-01-01

    The data packet buffering can be implemented in dual loop optical buffer (DLOB) through cross-phase modulation (XPM) between the control signal and the data packets. However, the output equality of dual wavelength signals will degrade due to the unbalanced gain and phase shift. This problem can be resolved by power equalization using the saturation characteristics of SOA. The data packets with 2.5 Gb/s can be buffered in DLOB for 16 cycles corresponding to 16.5 μs.The extinction ratio of the output packet is 8 dB while the S/N is 8.1 dB.

  10. Simulation experiments to generate broadband chaos using dual-wavelength optically injected Fabry-Perot laser

    Science.gov (United States)

    Obaid, Hafiz Muhammad; Khawar Islam, Muhammad; Obaid Ullah, Muhammad

    2016-08-01

    Broadband chaos can be generated by beating two wavelengths in a hybrid arrangement of Fabry-Perot (FP) Laser and Fiber ring cavity by injecting dual wavelengths. The bandwidth of generated chaos can be controlled by detuning different modes of FP Laser for beating. The bandwidth of generated chaos increased to many folds depending upon the injected strength and wavelength spacing matched to FP laser modes. The bandwidth enhancement in different simulation experiments conducted is optimized by varying different parameters of FP laser and cavity. The waveforms are analyzed and Lyapunov exponents are calculated in order to validate the existence of high bandwidth non-pulsating chaos.

  11. Tunable dual-wavelength filter and its group delay dispersion in domain-engineered lithium niobate

    Science.gov (United States)

    Shao, Guang-hao; Song, Jing; Ruan, Ya-ping; Cui, Guo-xin; Lu, Yan-qing

    2016-12-01

    A tunable dual-wavelength filter is experimentally demonstrated in domain-engineered lithium niobate. Application of an electric field on the y-surfaces of the sample results in the optical axes rotating clockwise and anticlockwise, which makes selective polarization rotation. The quasi phase-matching wavelengths could be adjusted through suitable domain design. A unique dual valley spectrum is obtained in a periodically poled lithium niobate structure with a central defect if the sample is placed between two parallel polarizers. The expected bandwidth could be varied from ˜1 nm to ˜40 nm. Moreover, both the spectral response and group delay dispersion could be engineered.

  12. Terahertz digital holography using angular spectrum and dual wavelength reconstruction methods.

    Science.gov (United States)

    Heimbeck, Martin S; Kim, Myung K; Gregory, Don A; Everitt, Henry O

    2011-05-09

    Terahertz digital off-axis holography is demonstrated using a Mach-Zehnder interferometer with a highly coherent, frequency tunable, continuous wave terahertz source emitting around 0.7 THz and a single, spatially-scanned Schottky diode detector. The reconstruction of amplitude and phase objects is performed digitally using the angular spectrum method in conjunction with Fourier space filtering to reduce noise from the twin image and DC term. Phase unwrapping is achieved using the dual wavelength method, which offers an automated approach to overcome the 2π phase ambiguity. Potential applications for nondestructive test and evaluation of visually opaque dielectric and composite objects are discussed.

  13. Y-branch integrated dual wavelength laser diode for microwave generation by sideband injection locking.

    Science.gov (United States)

    Huang, Jin; Sun, Changzheng; Xiong, Bing; Luo, Yi

    2009-11-01

    A Y-branch integrated dual wavelength laser diode is fabricated for optical microwave generation based on the principle of sideband injection locking. The device integrates a master laser and a slave laser with associated Y-branch coupler. By directly modulating the master laser near its relaxation resonance frequency, multiple sidebands are generated due to enhanced modulation nonlinearity. Beat signal with high spectral purity is obtained by injection locking the slave laser to one of the modulation sidebands. A millimeter-wave carrier of 42-GHz with a phase noise of -94.6 dBc/Hz at 10 kHz offset is demonstrated.

  14. Scanning ARM Cloud Radar Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  15. Generation of low jitter and discrete tunable dual-wavelength optical pulses at arbitrary repetition rates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-jiang; WANG Yun-cai

    2006-01-01

    A novel and simple method to generate low timing jitter and discrete tunable dual-wavelength optical pulses at arbitrary repetition rates is demonstrated in this paper.Two multiple quantum wells distributed feedback laser diodes,were used as the external seeding sources to inject the external photons into a gain-switched Fabry-Perot laser diode.The output wavelengths can be tuned discretely to coincide with any two lasing modes in the gain spectra range of the Fabry-Perot Laser diode,and the output side mode suppression ratio was better than 25 dB.Moreover,the timing jitter of optical pulses was reduced from 1.89 ps to 0.83 ps.It was empirically found that the lowest timing jitter operation occurred when the injected light wavelength is 0.2-0.3 nm shorter than the locked mode of the Fabry-Perot laser diode.To our knowledge,this is the first report of using two DFB laser diodes as a seeding source to reduce pulses jitter and select lasing dual-wavelength simultaneously.

  16. Dual-wavelength optical fluidic glucose sensor using time series analysis of d(+)-glucose measurement

    Science.gov (United States)

    Tang, Jing-Yau; Chen, Nan-Yueh; Chen, Ming-Kun; Wang, Min-Haw; Jang, Ling-Sheng

    2016-10-01

    This paper presents a rising-edge time-series analysis (TSA) method that can be applied to a dual-wavelength optical fluidic glucose sensor (DWOFGS). In the experiment, the concentration of glucose in phosphate buffered saline (PBS) was determined by measuring the absorbance of the solution as determined by variation in the rising edge of the photodiode (PD) voltage response waveform. The DWOFGS principle is based on near-infrared (NIR) absorption spectroscopy at selected dual wavelengths (1450 and 1650 nm) in the first overtone band. The DWOFGS comprises two light-emitting diodes (LEDs) and two PD detectors. No additional fibers or lenses are required in our device. The output light level of the LEDs is adjusted to a light intensity suitable to the glucose absorption rate in an electronic circuit. Four light absorbance paths enable detection of d(+)-glucose concentrations from 0 to 20 wt % in steps of 5 wt %. The glucose light absorbance process was calculated based on the rising edge of the PD waveform under a low-intensity light source using TSA. The TSA method can be used to obtain the glucose level in PBS and reduce measurement background noise. The application of the rising-edge TSA method improves sensor sensitivity, increases the accuracy of the data analysis, and lowers measurement equipment costs.

  17. Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar

    Science.gov (United States)

    Li, Zhan; Jupp, David L. B.; Strahler, Alan H.; Schaaf, Crystal B.; Howe, Glenn; Hewawasam, Kuravi; Douglas, Ewan S.; Chakrabarti, Supriya; Cook, Timothy A.; Paynter, Ian; Saenz, Edward J.; Schaefer, Michael

    2016-01-01

    Radiometric calibration of the Dual-Wavelength Echidna® Lidar (DWEL), a full-waveform terrestrial laser scanner with two simultaneously-pulsing infrared lasers at 1064 nm and 1548 nm, provides accurate dual-wavelength apparent reflectance (ρapp), a physically-defined value that is related to the radiative and structural characteristics of scanned targets and independent of range and instrument optics and electronics. The errors of ρapp are 8.1% for 1064 nm and 6.4% for 1548 nm. A sensitivity analysis shows that ρapp error is dominated by range errors at near ranges, but by lidar intensity errors at far ranges. Our semi-empirical model for radiometric calibration combines a generalized logistic function to explicitly model telescopic effects due to defocusing of return signals at near range with a negative exponential function to model the fall-off of return intensity with range. Accurate values of ρapp from the radiometric calibration improve the quantification of vegetation structure, facilitate the comparison and coupling of lidar datasets from different instruments, campaigns or wavelengths and advance the utilization of bi- and multi-spectral information added to 3D scans by novel spectral lidars. PMID:26950126

  18. Terahertz-wave differential detection based on simultaneous dual-wavelength up-conversion

    Directory of Open Access Journals (Sweden)

    Yuma Takida

    2017-03-01

    Full Text Available We report a terahertz (THz-wave differential detection based on simultaneous dual-wavelength up-conversion in a nonlinear optical MgO:LiNbO3 crystal with optical and electronic THz-wave sources. The broadband parametric gain and noncollinear phase-matching of MgO:LiNbO3 provide efficient conversion from superposed THz waves to spatially distributed near-infrared (NIR beams to function as a dispersive THz-wave spectrometer without any additional dispersive element. We show that the μW-level THz waves from two independent sources, a 0.78-THz injection-seeded THz-wave parametric generator (is-TPG and a 1.14-THz resonant tunneling diode (RTD, are simultaneously up-converted to two NIR waves and then detected with two NIR photodetectors. By applying a balanced detection scheme to this dual-frequency detection, we demonstrate THz-wave differential imaging of maltose and polyethylene pellets in the transmission geometry. This dual-wavelength detection is applicable to more than three frequencies and broadband THz-wave radiation for real-time THz-wave spectroscopic detection and imaging.

  19. Graphene-based passively Q-switched dual-wavelength erbium-doped fiber laser.

    Science.gov (United States)

    Luo, Zhengqian; Zhou, Min; Weng, Jian; Huang, Guoming; Xu, Huiying; Ye, Chenchun; Cai, Zhiping

    2010-11-01

    We demonstrate a compact Q-switched dual-wavelength erbium-doped fiber (EDF) laser based on graphene as a saturable absorber (SA). By optically driven deposition of graphene on a fiber core, the SA is constructed and inserted into a diode-pumped EDF laser cavity. Also benefiting from the strong third-order optical nonlinearity of graphene to suppress the mode competition of EDF, a stable dual-wavelength Q-switching operation has been achieved using a two-reflection peak fiber Bragg grating as the external cavity mirror. The Q-switched EDF laser has a low pump threshold of 6.5 mW at 974 nm and a wide range of pulse-repetition rate from 3.3 to 65.9 kHz. The pulse duration and the pulse energy have been characterized. This is, to the best of our knowledge, the first demonstration of a graphene-based Q-switched laser.

  20. Fast and sensitive optical toxicity bioassay based on dual wavelength analysis of bacterial ferricyanide reduction kinetics.

    Science.gov (United States)

    Pujol-Vila, F; Vigués, N; Díaz-González, M; Muñoz-Berbel, X; Mas, J

    2015-05-15

    Global urban and industrial growth, with the associated environmental contamination, is promoting the development of rapid and inexpensive general toxicity methods. Current microbial methodologies for general toxicity determination rely on either bioluminescent bacteria and specific medium solution (i.e. Microtox(®)) or low sensitivity and diffusion limited protocols (i.e. amperometric microbial respirometry). In this work, fast and sensitive optical toxicity bioassay based on dual wavelength analysis of bacterial ferricyanide reduction kinetics is presented, using Escherichia coli as a bacterial model. Ferricyanide reduction kinetic analysis (variation of ferricyanide absorption with time), much more sensitive than single absorbance measurements, allowed for direct and fast toxicity determination without pre-incubation steps (assay time=10 min) and minimizing biomass interference. Dual wavelength analysis at 405 (ferricyanide and biomass) and 550 nm (biomass), allowed for ferricyanide monitoring without interference of biomass scattering. On the other hand, refractive index (RI) matching with saccharose reduced bacterial light scattering around 50%, expanding the analytical linear range in the determination of absorbent molecules. With this method, different toxicants such as metals and organic compounds were analyzed with good sensitivities. Half maximal effective concentrations (EC50) obtained after 10 min bioassay, 2.9, 1.0, 0.7 and 18.3 mg L(-1) for copper, zinc, acetic acid and 2-phenylethanol respectively, were in agreement with previously reported values for longer bioassays (around 60 min). This method represents a promising alternative for fast and sensitive water toxicity monitoring, opening the possibility of quick in situ analysis.

  1. Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar.

    Science.gov (United States)

    Li, Zhan; Jupp, David L B; Strahler, Alan H; Schaaf, Crystal B; Howe, Glenn; Hewawasam, Kuravi; Douglas, Ewan S; Chakrabarti, Supriya; Cook, Timothy A; Paynter, Ian; Saenz, Edward J; Schaefer, Michael

    2016-03-02

    Radiometric calibration of the Dual-Wavelength Echidna(®) Lidar (DWEL), a full-waveform terrestrial laser scanner with two simultaneously-pulsing infrared lasers at 1064 nm and 1548 nm, provides accurate dual-wavelength apparent reflectance (ρ(app)), a physically-defined value that is related to the radiative and structural characteristics of scanned targets and independent of range and instrument optics and electronics. The errors of ρ(app) are 8.1% for 1064 nm and 6.4% for 1548 nm. A sensitivity analysis shows that ρ(app) error is dominated by range errors at near ranges, but by lidar intensity errors at far ranges. Our semi-empirical model for radiometric calibration combines a generalized logistic function to explicitly model telescopic effects due to defocusing of return signals at near range with a negative exponential function to model the fall-off of return intensity with range. Accurate values of ρ(app) from the radiometric calibration improve the quantification of vegetation structure, facilitate the comparison and coupling of lidar datasets from different instruments, campaigns or wavelengths and advance the utilization of bi- and multi-spectral information added to 3D scans by novel spectral lidars.

  2. Dual-wavelength retinal images denoising algorithm for improving the accuracy of oxygen saturation calculation

    Science.gov (United States)

    Xian, Yong-Li; Dai, Yun; Gao, Chun-Ming; Du, Rui

    2017-01-01

    Noninvasive measurement of hemoglobin oxygen saturation (SO2) in retinal vessels is based on spectrophotometry and spectral absorption characteristics of tissue. Retinal images at 570 and 600 nm are simultaneously captured by dual-wavelength retinal oximetry based on fundus camera. SO2 is finally measured after vessel segmentation, image registration, and calculation of optical density ratio of two images. However, image noise can dramatically affect subsequent image processing and SO2 calculation accuracy. The aforementioned problem remains to be addressed. The purpose of this study was to improve image quality and SO2 calculation accuracy by noise analysis and denoising algorithm for dual-wavelength images. First, noise parameters were estimated by mixed Poisson-Gaussian (MPG) noise model. Second, an MPG denoising algorithm which we called variance stabilizing transform (VST) + dual-domain image denoising (DDID) was proposed based on VST and improved dual-domain filter. The results show that VST + DDID is able to effectively remove MPG noise and preserve image edge details. VST + DDID is better than VST + block-matching and three-dimensional filtering, especially in preserving low-contrast details. The following simulation and analysis indicate that MPG noise in the retinal images can lead to erroneously low measurement for SO2, and the denoised images can provide more accurate grayscale values for retinal oximetry.

  3. Hybrid ultrasound and dual-wavelength optoacoustic biomicroscopy for functional neuroimaging

    Science.gov (United States)

    Rebling, Johannes; Estrada, Hector; Zwack, Michael; Sela, Gali; Gottschalk, Sven; Razansky, Daniel

    2017-03-01

    Many neurological disorders are linked to abnormal activation or pathological alterations of the vasculature in the affected brain region. Obtaining simultaneous morphological and physiological information of neurovasculature is very challenging due to the acoustic distortions and intense light scattering by the skull and brain. In addition, the size of cerebral vasculature in murine brains spans an extended range from just a few microns up to about a millimeter, all to be recorded in 3D and over an area of several dozens of mm2. Numerous imaging techniques exist that excel at characterizing certain aspects of this complex network but are only capable of providing information on a limited spatiotemporal scale. We present a hybrid ultrasound and dual-wavelength optoacoustic microscope, capable of rapid imaging of murine neurovasculature in-vivo, with high spatial resolution down to 12 μm over a large field of view exceeding 50mm2. The dual wavelength imaging capability allows for the visualization of functional blood parameters through an intact skull while pulse-echo ultrasound biomicroscopy images are captured simultaneously by the same scan head. The flexible hybrid design in combination with fast high-resolution imaging in 3D holds promise for generating better insights into the architecture and function of the neurovascular system.

  4. Dual-wavelength synchronously Q-switched solid-state laser with multi-layered graphene as saturable absorber.

    Science.gov (United States)

    Zhao, Yongguang; Li, Xianlei; Xu, Miaomiao; Yu, Haohai; Wu, Yongzhong; Wang, Zhengping; Hao, Xiaopeng; Xu, Xinguang

    2013-02-11

    Using multilayered graphene as the saturable absorber (SA), Nd:LYSO crystal as the laser material, we demonstrated a laser-diode (LD) pumped, dual-wavelength passively Q-switched solid-state laser. The maximum average output power is 1.8 W, the largest pulse energy and highest peak power is 11.3 μJ, 118 W, respectively. As we have known, they are the best results for passively Q-switched operation of graphene. The pulse laser is strong enough to realize extra-cavity frequency conversions. With a KTP crystal as the sum-frequency generator, the dual wavelengths are proved to be well time overlapped, which manifests the synchronous modulation to the dual-wavelength with multi-layered graphene.

  5. Ka-Band Parabolic Deployable Antenna (KaPDA) Enabling High Speed Data Communication for CubeSats

    Science.gov (United States)

    Sauder, Jonathan F.; Chahat, Nacer; Hodges, Richard; Thomson, Mark W.; Rahmat-Samii, Yahya

    2015-01-01

    CubeSats are at a very exciting point as their mission capabilities and launch opportunities are increasing. But as instruments become more advanced and operational distances between CubeSats and earth increase communication data rate becomes a mission-limiting factor. Improving data rate has become critical enough for NASA to sponsor the Cube Quest Centennial Challenge when: one of the key metrics is transmitting as much data as possible from the moon and beyond Currently, many CubeSats communicate on UHF bands and those that have high data rate abilities use S-band or X-band patch antennas. The CubeSat Aneas, which was launched in September 2012, pushed the envelope with a half-meter S-band dish which could achieve 100x the data rate of patch antennas. A half-meter parabolic antenna operating at Ka-band would increase data rates by over 100x that of the AMOS antenM and 10,000 that of X-band patch antennas.

  6. A low-noise K-Ka band oscillator using AlGaAs/GaAs heterojunction bipolar transistors

    Science.gov (United States)

    Madihian, Mohammad; Takahashi, Hideki

    1991-01-01

    The design considerations, fabrication process, and performance of the first K-Ka-band oscillator implemented using a self-aligned AlGaAs/GaAs heterojunction bipolar transistor (HBT) are described. A large-signal time-domain-based design approach has been used which applies a SPICE-F simulator for optimization of the oscillator circuit parameters for maximum output power. The oscillator employs a 2 x 10 sq mm emitter AlGaAs/GaAs HBT that was fabricated using a pattern inversion technology. The HBT has a base current 1/f noise power density lower than 1 x 10 to the -20th sq A/Hz at 1 kHz and lower than 1 x 10 to the -22nd sq A/Hz at 100 kHz for a collector current of 1 mA. The oscillator, which is composed of only low-Q microstrip transmission lines, has a phase noise of -80 dBc/Hz at 100 kHz off carrier when operated at 26.6 GHz. These results indicate the applicability of the HBTs to low-phase-noise monolithic oscillators at microwave and millimeter-wave frequencies, where both Si bipolar transistors and GaAs FETs are absent.

  7. High-accuracy alignment based on atmospherical dispersion - technological approaches and solutions for the dual-wavelength transmitter

    Energy Technology Data Exchange (ETDEWEB)

    Burkhard, Boeckem [Institute for Geodesy and Photogrammetry, ETH Zurich (Switzerland)

    1999-07-01

    In the course of the progressive developments of sophisticated geodetic systems utilizing electromagnetic waves in the visible or near IR-range a more detailed knowledge of the propagation medium and coevally solutions of atmospherically induced limitations will become important. An alignment system based on atmospherical dispersion, called a dispersometer, is a metrological solution to the atmospherically induced limitations, in optical alignment and direction observations of high accuracy. In the dispersometer we are using the dual-wavelength method for dispersive air to obtain refraction compensated angle measurements, the detrimental impact of atmospheric turbulence notwithstanding. The principle of the dual-wavelength method utilizes atmospherical dispersion, i.e. the wavelength dependence of the refractive index. The difference angle between two light beams of different wavelengths, which is called the dispersion angle {delta}{beta}, is to first approximation proportional to the refraction angle: {beta}{sub IR} {nu}({beta}{sub blue} - {beta}{sub IR}) = {nu} {delta}{beta}, this equation implies that the dispersion angle has to be measured at least 42 times more accurate than the desired accuracy of the refraction angle for the wavelengths used in the present dispersometer. This required accuracy constitutes one major difficulty for the instrumental performance in applying the dispersion effect. However, the dual-wavelength method can only be successfully used in an optimized transmitter-receiver combination. Beyond the above mentioned resolution requirement for the detector, major difficulties in instrumental realization arise in the availability of a suitable dual-wavelength laser light source, laser light modulation with a very high extinction ratio and coaxial emittance of mono-mode radiation at both wavelengths. Therefore, this paper focuses on the solutions of the dual-wavelength transmitter introducing a new hardware approach and a complete re-design of

  8. Dual Wavelength Laser Writing and Measurement Methodology for High Resolution Bimetallic Grayscale Photomasks

    Science.gov (United States)

    Qarehbaghi, Reza

    Grayscale bimetallic photomasks consist of bi-layer thermal resists (Bismuth-on-Indium or Tin-on-Indium) which become controllably transparent when exposed to a focused laser beam as a function of the absorbed power changing from ~3OD (unexposed) to writing. This thesis investigates using two wavelength beams for mask writing (514.5nm) and OD measurement (457.9nm) separated from a multi-line Argon ion laser source: a Dual Wavelength Writing and Measurement System. The writing laser profile was modified to a top-hat using a beam shaper. Several mask patterns tested the creation of high resolution grayscale masks. Finally, for creation of 3D structures in photoresist, the mask transparency to resist thickness requirements was formulated and linear slope patterns were successfully created.

  9. Dual-wavelength polymer laser based on an active/inactive/active sandwich-like structure

    Science.gov (United States)

    Zhai, Tianrui; Wu, Xiaofeng; Wang, Meng; Tong, Fei; Li, Songtao; Ma, Yanbin; Deng, Jinxiang; Zhang, Xinping

    2016-09-01

    Dual-wavelength laser emission is achieved by using an active/inactive/active sandwich-like structure, which can be conveniently fabricated using spin coating technique. Poly [(9, 9-dioctylfluorenyl-2, 7-diyl)-alt-co-(1, 4-benzo-(2, 1', 3) -thiadiazole)] and polyvinyl alcohol are employed as the active and the inactive materials, respectively. Two laser wavelengths are simultaneously observed, which are attributed to the difference of the surrounding refractive index of two active waveguides in the sandwich-like structure. Each wavelength is controlled by the respective waveguide structure, meaning that multi-wavelength laser can be designed by stacking the active/inactive layer pair. These results provide more flexibility to design compact laser sources.

  10. Reduction of implantation shadowing effect by dual-wavelength exposure photo process

    CERN Document Server

    Gu, Yiming; Lee Sang Yun; Roche, William; Sturtevant, John

    2003-01-01

    As transistor engineering continues to well below 100 nm length devices, ion implantation process tolerances are making these formerly "non-critical" lithography levels more and more difficult. In order to minimize the channeling effect and to obtain a controllable profile of dopant, an angle implantation is often required. However, a shadow area of resist pattern is always accompanied with an angle implantation. This shadowing effect consumes silicon real estate, and reduces the line edge placement (LEP) tolerances. Therefore, methodologies to reduce the shadowing effect in angled implantation become a critical consideration not only for device engineering but also for photolithography. Based on the model analysis, simulation and experiments, this paper presents an effective novel process utilizing dual-wavelength exposure (DWE) to reduce the shadowing effect. The DWE process is realized by two consecutive exposures for an I-line resist with a DUV stepper/scanner and an I-line stepper. The process leverages ...

  11. Dual-wavelength diode laser with electrically adjustable wavelength distance at 785  nm.

    Science.gov (United States)

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2016-08-15

    A spectrally adjustable monolithic dual-wavelength diode laser at 785 nm as an excitation light source for shifted excitation Raman difference spectroscopy (SERDS) is presented. The spectral distance between the two excitation wavelengths can be electrically adjusted between 0 and 2.0 nm using implemented heater elements above the distributed Bragg reflector (DBR) gratings. Output powers up to 180 mW at a temperature of 25°C were measured. The spectral width is smaller than 13 pm, limited by the spectrum analyzer. The device is well-suited for Raman spectroscopy, and the flexible spectral distance allows a target-specific adjustment of the excitation light source for shifted excitation Raman difference spectroscopy (SERDS).

  12. A low cost scheme for high precision dual-wavelength laser metrology

    CERN Document Server

    Kok, Yitping; Robertson, J Gordon; Tuthill, Peter G; Warrington, Benjamin A; Tango, William J

    2013-01-01

    A novel method capable of delivering relative optical path length metrology with nanometer precision is demonstrated. Unlike conventional dual-wavelength metrology which employs heterodyne detection, the method developed in this work utilizes direct detection of interference fringes of two He-Ne lasers as well as a less precise stepper motor open-loop position control system to perform its measurement. Although the method may be applicable to a variety of circumstances, the specific application where this metrology is essential is in an astrometric optical long baseline stellar interferometer dedicated to precise measurement of stellar positions. In our example application of this metrology to a narrow-angle astrometric interferometer, measurement of nanometer precision could be achieved without frequency-stabilized lasers although the use of such lasers would extend the range of optical path length the metrology can accurately measure. Implementation of the method requires very little additional optics or el...

  13. Switchable dual-wavelength erbium-doped fiber laser with a tilted fiber grating

    Institute of Scientific and Technical Information of China (English)

    JIN Long; KAI Gui-yun; XU Ling-ling; LIU Bo; ZHANG Jian; LIU Yan-ge; YUAN Shu-zhong; DONG Xiao-yi

    2007-01-01

    A dual-wavelength erbium doped fiber laser with a tilted fiber Bragg grating and photonic crystal fiber is proposed and demonstrated. In the laser,a 2W EDFA provides gain for all the laser lines; the highly nonlinear photonic crystal fiber introduces dynamic energy transfer between the two wavelengths caused by four wave mixing effect,so that a stable dualwavelength oscillation at room temperature is implemented. Different switching modes can be achieved by adjusting the lateral offset between the fiber grating and the guiding single mode fiber or by varying the state of polarization in the laser cavity. The maximum of output power of the laser has reached 314 mW.

  14. Dual-wavelength single-frequency laser emission in asymmetric coupled microdisks

    Science.gov (United States)

    Wang, Haotian; Liu, Sheng; Chen, Lin; Shen, Deyuan; Wu, Xiang

    2016-12-01

    The gain and loss in a microcavity laser play an important role for the modulation of laser spectrum. We show that dual-wavelength single mode lasing can be achieved in an asymmetric coupled system consisted of two size-mismatched microdisks. The amount of eigenmodes in this coupled-microdisk system is reduced relying on the Vernier effect. Then a single mode is selected to lase by controlling the gain branching in the supermodes. The supermodes are formed by the coupling between different transverse whispering-gallery modes (WGMs). When the gain/loss status between the two mirodisks is changed through selectively pumping process, the modulated gain branching for various supermodes leads to the switchable single-frequency laser emission. The results obtained in this work will provide the further understand for the spectral modulation mechanism in the coupled microcavity laser system.

  15. All-fiber dual-wavelength laser delivering two types of solitons

    Science.gov (United States)

    Li, W. L.

    2015-05-01

    We have proposed a compact all-fiber dual-wavelength laser based on a fiber Bragg grating (FBG) and semiconductor saturable absorber mirror (SESAM). The proposed laser mode locked by single-walled carbon nanotubes (SWNTs) delivers two kinds of solitons with pulse durations of ~1 ps and ~20 ps. The spectral width of the longer soliton pulses is ~0.14 nm, which attributes to the narrow bandwidth of the FBG. Shorter pulses with a spectral width of ~4 nm are mainly determined by the cavity length and intracavity dispersion. Our method provides a simple, stable, low-cost, and dual-scale ultrafast-pulsed laser source suitable for practical applications in optical communications and sensing.

  16. Multi-Rare-Earth Ions Codoped Tellurite Glasses for Potential Dual Wavelength Fibre-Optic Amplifiers

    Institute of Scientific and Technical Information of China (English)

    DAI Shi-Xun; YANG Jian-Hu; XU Shi-Qing; DAI Neng-Li; WEN Lei; HU Li-Li; JIANG Zhong-Hong

    2003-01-01

    A novel co-doping method of multi-rare-earth (RE) ions was demonstrated in tellurite glasses for fibre amplifiers. Fluorescence emissions at both 1.53 and 1.63 fj,m communication windows were Brstly observed from Er3+ /Yb3+ /Tm3+ -codoped tellurite glasses under a single wavelength pumping at 980 nm. The full width at half maximum of Suorescence at 1.53 and 1.63 [im are 55 nm and 50 urn, respectively. Tm's codoping method of three RE ions could be applied to other low photon energy glasses, which would be possibly used for potential dual wavelength fibre-optic amplifiers to broaden the communication windows.

  17. A Single-Longitudinal-Mode Dual-Wavelength cw Tm,Ho: GdVO4 Microchip Laser

    Institute of Scientific and Technical Information of China (English)

    JU You-Lun; WANG Zhen-Guo; LI Yu-Feng; WANG Yue-Zhu

    2008-01-01

    A liquid nitrogen cooled dual-wavelength Tm,Ho:GdVO4 microchip laser is reported. The output dual wavelengths are at 2038.9nm and 2050.1nm. At each wavelength, the laser has a single longitudinal mode. The threshold power is nearly 20mW and the slope efficiency is 18.7%. The single longitudinal mode output power reaches 98mW, and the ratio of power is about 60% (2038.9nm) and 40% (2050.1 nm).

  18. Tunable and switchable dual-wavelength Tm-doped mode-locked fiber laser by nonlinear polarization evolution.

    Science.gov (United States)

    Yan, Zhiyu; Li, Xiaohui; Tang, Yulong; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2015-02-23

    We propose and demonstrate a tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser. The tunability is based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity. The NPE effect induces wavelength-dependent loss in the cavity to effectively alleviate mode competition and enables the multiwavelength mode locking. The laser exhibits tunable dual-wavelength mode locking over a wide range from 1852 to 1886 nm. The system has compact structure and both the wavelength tuning and switching capabilities can be realized by controlling the polarization in the fiber ring cavity.

  19. Red emitting monolithic dual wavelength DBR diode lasers for shifted excitation Raman difference spectroscopy

    Science.gov (United States)

    Sumpf, B.; Maiwald, M.; Müller, A.; Bugge, F.; Fricke, J.; Ressel, P.; Pohl, J.; Erbert, G.; Tränkle, G.

    2014-02-01

    Raman lines are often obscured by background light or fluorescence especially when investigating biological samples or samples containing impurities. Shifted excitation Raman difference spectroscopy (SERDS) is a technique to overcome this. By exciting the sample with two slightly shifted wavelengths, it is possible to separate the Raman lines and distortions. In this paper, monolithic dual wavelength DBR diode lasers meeting the demands of Raman spectroscopy and SERDS will be presented. The wavelengths are stabilized and selected by using deeply-etched 10th order surface gratings with different periods manufactured using i-line wafer stepper lithography. Two possible resonator concepts, i.e. a mini-array of two parallel DBR RW-lasers and a Y-branch DBR laser, will be compared. Established excitation wavelengths for Raman spectroscopy at 671 nm and 785 nm are chosen. The total laser length is 3 mm; the ridge width is 2.2 μm for the 785 nm devices and 5 μm for the 671 nm lasers. The length of the DBR gratings is 500 μm. The devices at 671 nm reach output powers up to 100 mW having an emission width smaller than 12 pm (FWHM). The 785 nm lasers show output powers up to 200 mW and a narrow emission below 22 pm. For the dual wavelength lasers the spectral distance between the two excitation lines is about 0.5 nm as targeted. The power consumption at both wavelengths is below 1 W. These data proof that the devices are well suited for their application in portable Raman measurement systems such as handheld devices using SERDS.

  20. Design on a Ka-band Up-converter Module%Ka频段上变频模块设计

    Institute of Scientific and Technical Information of China (English)

    陈焕东

    2011-01-01

    A new Ka-band Up-converter module is described in this paper.How to achieve low spurious and low phase noise performance is studied,and then the feasible scheme is designed.The filter is co-simulated by Ansoft Designer and HFSS software and is realized with thin film technique.High spurious suppression is obtained by the filter.A 27 GHz local oscillator with very low phase noise is realized by sampling phase-locked technique.The waveguide to micro-strip transition is simulated.Finally the module is tested,and the design objective is satisfied.%论述一种Ka频段上变频模块设计,对模块的杂散和相位噪声性能做了分析,根据分析结果,设计出合理的变频方案。滤波器采用Ansoft Designer和HFSS软件协同仿真,薄膜工艺制作,获得足够的杂散抑制度从而实现低杂散。应用取样锁相技术合成了相位噪声极低的27 GHz本振。对波导—微带过渡结构进行仿真,并给出仿真结果。从测试结果表明,模块设计实现了低杂散和低相位噪声。

  1. Design of Ka band MMIC VCO%Ka波段单片压控振荡器的设计

    Institute of Scientific and Technical Information of China (English)

    李鹏亮; 马伟

    2014-01-01

    基于0.25μm GaAs pHEMT工艺设计了Ka波段单片压控振荡器,该压控振荡器采用源极正反馈结构,变容管采用源极和漏极接地的pHEMT管。通过优化输出匹配网络和谐振网络以改善输出功率和相位噪声性能,使用蒙特卡洛成品率分析对本设计的成品率进行分析和改进。版图仿真结果显示:芯片输出频率为24.6~26.3 GHz,输出功率为(10±1)dBm,谐波抑制大于19 dB,芯片尺寸为1.5 mm×1 mm。%A Ka-band MMIC VCO was designed with 0.25 μm GaAs pHEMT process. The source electrode positive feed-back structure is adopted for VCO. The pHEMT whose source electrode and drain electrode are connected to the ground is used for the varactor. The resonance network and the matching network are optimized to improve the output power and the phase noise performance. The yield of the VCO is analyzed and improved by the Monte-Carlo method. The simulation data shows the typical output power of VCO is 10±1 dBm,the output frequency of VCO is 24.6~26.3 GHz,the harmonic suppression is better than 19 dB. The chip size of the MMIC VCO is 1.5 mm×1 mm.

  2. Power-ratio tunable dual-wavelength laser using linearly variable Fabry-Perot filter as output coupler.

    Science.gov (United States)

    Wang, Xiaozhong; Wang, Zhongfa; Bu, Yikun; Chen, Lujian; Cai, Guoxiong; Huang, Wencai; Cai, Zhiping; Chen, Nan

    2016-02-01

    For a linearly variable Fabry-Perot filter, the peak transmission wavelengths change linearly with the transverse position shift of the substrate. Such a Fabry-Perot filter is designed and fabricated and used as an output coupler of a c-cut Nd:YVO4 laser experimentally in this paper to obtain a 1062 and 1083 nm dual-wavelength laser. The peak transmission wavelengths are gradually shifted from 1040.8 to 1070.8 nm. The peak transmission wavelength of the Fabry-Perot filter used as the output coupler for the dual-wavelength laser is 1068 nm and resides between 1062 and 1083 nm, which makes the transmissions of the desired dual wavelengths change in opposite slopes with the transverse shift of the filter. Consequently, powers of the two wavelengths change in opposite directions. A branch power, oppositely tunable 1062 and 1083 nm dual-wavelength laser is successfully demonstrated. Design principles of the linear variable Fabry-Perot filter used as an output coupler are discussed. Advantages of the method are summarized.

  3. Dual-wavelength speckle-based SI-POF sensor for frequency detection and localization of remote vibrations

    Science.gov (United States)

    Pinzón, P. J.; Montero, D. S.; Tapetado, A.; Torres, J. C.; Vázquez, C.

    2016-05-01

    A novel speckle-based method for sensing frequency vibration is demonstrated in a reflective configuration. By employing a visible dual-wavelength approach it is also possible to determine the relative spatial location of the vibrations along a plastic optical fiber lead of 8 m in a distributed scheme.

  4. Visible light stimulating dual-wavelength emission and O vacancy involved energy transfer behavior in luminescence for coaxial nanocable arrays

    Science.gov (United States)

    Yang, Lei; Dong, Jiazhang; Jiang, Zhongcheng; Pan, Anlian; Zhuang, Xiujuan

    2014-06-01

    We report a strategy to investigate O vacancy (VO) involved energy transfer and dual-wavelength yellow emission in coaxial nanocable. By electric field deposition and subsequent sol-gel template approach, ZnO:Tb/Y2O3:Eu coaxial nanocable arrays are synthesized. After visible light excitation, system is promoted to O vacancy charge transfer state of VO(0/+). In the following cross relaxation, energy transfer from VO to the excitation energy level of Tb3+ in ZnO:Tb core area. While in Y2O3:Eu shell area, energy transfer to the excitation energy level of Eu3+. Subsequently, dual-wavelength emission is observed. By constructing nanocable with dual-wavelength emission, yellow luminescence is obtained. Adjust doping concentration of Eu3+ or Tb3+ in the range of 0.01-0.05, chromaticity coordinates of ZnO:Tb/Y2O3:Eu nanocable stably stays at yellow region in color space except ZnO:Tb0.01/Y2O3:Eu0.01. As Vo states act as media in energy transfer process in nanocablers, visible light can stimulate dual-wavelength emissions. Yellow luminescent nanocable arrays will have great applications in light-emitting diode luminescence.

  5. An FSS-Backed 20/30 GHz Circularly Polarized Reflectarray for a Shared Aperture L- and Ka-Band Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst; Gothelf, Ulrich; Kim, Oleksiy S.

    2014-01-01

    A shared aperture antenna for simultaneous operation at L- (1525 to 1661 MHz) and Ka-band (19.7 to 20.2 GHz and 29.5 to 30.0 GHz) is demonstrated. This stacked antenna consists of a Ka-band reflectarray antenna with a frequency selective surface (FSS) ground-plane above an L-band patch array...... antenna. The reflectarray is based on the concentric dual split-loop element backed by a concentric dual-loop FSS element. The reflectarray comprises 80 × 80 elements and it is printed on a 40 ×40 cm2 Rogers 5880 substrate, while the L-band antenna is a 2 × 2 patch array. The reflectarray antenna has been...

  6. Feasibility Study on Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep-Space Ka-Band and Optical Communications

    Science.gov (United States)

    Lee, S.; Ortiz, G. G.; Roberts, W. T.; Alexander, J. W.

    2003-11-01

    The feasibility of using long-wavelength Earth thermal (infrared) images for antenna/ telescope tracking/pointing applications for both deep-space Ka-band (18 to 35 GHz) and free-space optical communications has been investigated and is reported on here. The advantage of this technology rests on using full Earth images in this band that yield more accurate estimates of geometric centroids than those of Earth images in the visible band. Furthermore, these images are nearly independent of Earth phase angle. The results of the study show that, at a Mars range with currently available sensors, a noise equivalent angle of 10 to 150 nrad and a bias error of better than 80 nrad can be obtained. This would enable precise pointing of both the optical and Ka-band communications beams.

  7. A Tunable Dual-Wavelength Fiber Ring Laser with a Fabry-Perot Laser Diode in an External Injection Seeding Scheme

    Institute of Scientific and Technical Information of China (English)

    Peng-Chun Peng; Hong-Yih Tseng; Sien Chi

    2003-01-01

    A tunable dual-wavelength fiber ring laser with a Fabry-Perot laser diode is proposed and demonstrated. The dual-wavelength outputs have the optical side-mode-suppression-ratio (SMSR) over 31 dB. The wavelength tuning range can be up to 9 nm.

  8. A Tunable Dual-Wavelength Fiber Ring Laser with a Fabry-Perot Laser Diode in an External Injection Seeding Scheme

    Institute of Scientific and Technical Information of China (English)

    Hong-Yih; Tseng; Sien; Chi

    2003-01-01

    A tunable dual-wavelength fiber ring laser with a Fabry-Perot laser diode is proposed and demonstrated. The dual-wavelength outputs have the optical side-mode-suppression-ratio (SMSR) over 31 dB. The wavelength tuning range can be up to 9 run.

  9. Investigation of Ka-Band CW 250 W TWT%Ka波段250W连续波行波管的研制

    Institute of Scientific and Technical Information of China (English)

    冯晨; 杨明华; 黄拓朴

    2011-01-01

    本文介绍了一种Ka波段连续波250 W螺旋线行波管研制的主要技术方案.介绍了这种行波管的研究现状和研制成果.%This paper presents the main technology scheme of a CW 250 W Ka-band helix TWT. The current situation of this TWT and the research achievements are introduced.

  10. Multi-species trace gas analysis with dual-wavelength quantum cascade laser

    Science.gov (United States)

    Jágerská, Jana; Tuzson, Béla; Looser, Herbert; Jouy, Pierre; Hugi, Andreas; Mangold, Markus; Soltic, Patrik; Faist, Jérôme; Emmenegger, Lukas

    2015-04-01

    Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly appealing for a large variety of applications ranging from air quality monitoring, medical breath analysis to industrial process control. However, state-of-the-art distributed-feedback (DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally leads to one-laser-one-compound measurement strategy. Thus, multi-species detection involves several lasers and elaborate beam combining solutions [1]. This makes them bulky, costly, and highly sensitive to optical alignment, which limits their field deployment. In this paper, we explore an alternative measurement concept based on a dual-wavelength quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct wavelengths using a succession of two DFB gratings with different periodicities and a common waveguide to produce one output beam. The laser design was optimized for NOx measurements and correspondingly emits single-mode at 5.26 and 6.25 μm. Electrical separation of the respective laser sections makes it possible to address each wavelength independently. Thereby, it is possible to detect NO and NO2 species with one laser using the same optical path, without any beam combining optics, i.e. in a compact and cost-efficient single-path optical setup. Operated in a time-division multiplexed mode, the spectrometer reaches detection limits at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system was validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as monitoring the pollution at a suburban site. [1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, and L. Emmenegger, 'Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy,' Atmospheric Measurement Techniques 6, 927-936 (2013

  11. Analysis of Fade Detection and Compensation Experimental Results in a Ka-Band Satellite System. Degree awarded by Akron Univ., May 2000

    Science.gov (United States)

    Johnson, Sandra

    2001-01-01

    The frequency bands being used for new satellite communication systems are constantly increasing to accommodate the requirements for additional capacity. At these higher frequencies, propagation impairments that did not significantly affect the signal at lower frequencies begin to have considerable impact. In Ka-band, the next logical commercial frequency band to be used for satellite communication, attenuation of the signal due to rain is a primary concern. An experimental satellite built by NASA, the Advanced Communication Technology Satellite (ACTS), launched in September 1993, is the first US communication satellite operating in the Ka-band. In addition to higher carrier frequencies, a number of other new technologies, including onboard baseband processing, multiple beam antennas, and rain fade detection and compensation techniques, were designed into the ACTS. Verification experiments have been conducted since the launch to characterize the new technologies. The focus of this thesis is to describe and validate the method used by the ACTS Very Small Aperture Terminal (VSAT) ground stations in detecting the presence of fade in the communication signal and to adaptively compensate for it by the addition of burst rate reduction and forward error correction. Measured data obtained from the ACTS program is used to validate the compensation technique. In this thesis, models in MATLAB are developed to statistically characterize the increased availability achieved by the compensation techniques in terms of the bit error rate time enhancement factor. Several improvements to the ACTS technique are discussed and possible implementations for future Ka-band systems are also presented.

  12. High Efficiency Traveling-Wave Tube Power Amplifier for Ka-Band Software Defined Radio on International Space Station-A Platform for Communications Technology Development

    Science.gov (United States)

    Simons, Rainee N.; Force, Dale A.; Kacpura, Thomas J.

    2013-01-01

    The design, fabrication and RF performance of the output traveling-wave tube amplifier (TWTA) for a space based Ka-band software defined radio (SDR) is presented. The TWTA, the SDR and the supporting avionics are integrated to forms a testbed, which is currently located on an exterior truss of the International Space Station (ISS). The SDR in the testbed communicates at Ka-band frequencies through a high-gain antenna directed to NASA s Tracking and Data Relay Satellite System (TDRSS), which communicates to the ground station located at White Sands Complex. The application of the testbed is for demonstrating new waveforms and software designed to enhance data delivery from scientific spacecraft and, the waveforms and software can be upgraded and reconfigured from the ground. The construction and the salient features of the Ka-band SDR are discussed. The testbed is currently undergoing on-orbit checkout and commissioning and is expected to operate for 3 to 5 years in space.

  13. Ka-Band Wide-Bandgap Solid-State Power Amplifier: Prototype Combiner Spurious Mode Suppression and Power Constraints

    Science.gov (United States)

    Khan, P.; Epp, L.

    2006-01-01

    Results of prototype hardware activities related to a 120-W, 32-GHz (Ka-band) solid-state power amplifier (SSPA) architecture study are presented. Spurious mode suppression and the power-handling capability of a prototype 24-way radial combiner and a prototype 2-way septum binary combiner were investigated. Experimental data indicate that a commercial absorptive filter, designed to pass the circular TE01 mode, effectively suppressed the higher-order modes generated by a narrowband, flower-petal-type mode transducer. However, the same filter was not effective in suppressing higher-order modes generated by the broadband Marie mode transducer that is used in the prototype waveguide radial combiner. Should greater filtering be required by a particular SSPA application, a broadband mode filter that can suppress specifically those higher-order modes that are generated by the Marie transducer will need to be developed. A back-to-back configuration of the prototype radial combiner was tested with drive power up to approximately 50 W. No anomalous behavior was observed. Power measurements of the septum combiner indicate that up to 10-W radio frequency (RF) can be dissipated in the integrated resistive element before a permanent performance shift is observed. Thus, a given adder (a single-stage, 2-way combiner) can safely combine two 20-W sources, and the adder will not be damaged in the event of a source failure. This result is used to calculate the maximum source power that can be safely combined as a function of the number of sources combined and the number of source failures allowed in a multi-stage combiner. The analysis shows that SSPA power >140 W can be generated by power combining 16 sources producing 10 W each. In this configuration, up to three sources could fail with the guarantee that the combiner would not be damaged. Finally, a modified prototype septum combiner design was verified. The improved design reduced the assembly time from over 2 hours to about 15

  14. Dual wavelength fluorescent ratiometric pH measurement by scanning near-field optical microscopy

    Science.gov (United States)

    Li, Yongbo; Shinohara, Ryosuke; Iwami, Kentaro; Ohta, Yoshihiro; Umeda, Norihiro

    2010-08-01

    A novel method to observe pH distribution by dual wavelength fluorescent ratiometric pH measurement by scanning near-field optical microscopy (SNOM) is developed. In this method, in order to investigate not only the pH of mitochondrial membrane but also its distribution in the vicinity, a pH sensitive fluorescent reagent covers mitochondria instead of injecting it to mitochondria. This method utilizes a dual-emission pH sensitive dye and SNOM with a themally-pulled and metal-coated optical fiber to improve the spatial resolution. Time-dependence of Fluorescent intensity ratio (FIR) under acid addition is investigated. As the distances between the dropped point and the SNOM probe becomes closer, the time when FIR changes becomes earlier. The response of mitochondria under supplement of nutrition is studied by using this method. While the probe is near to mitochondria, the ratio quickly becomes to increase. In conclusion, it was confirmed that the temporal variation of pH can be detected by this method, and pH distribution in the vicinity of mitochondria is able to be measured by this method.

  15. Online industrial thermography of die casting tooling using dual-wavelength IR imaging

    Science.gov (United States)

    Kourous, Helen E.; Shabestari, Behrouz N.; Luster, Spencer D.; Sacha, Jaroslaw P.

    1998-03-01

    Recent advances in IR system technology coupled with significant reduction sin cost are making thermography a viable tool for on-line monitoring of industrial processes. This paper describes the implementation of a novel rugged thermal imaging system based on a dual-wavelength technique for a large intelligent process monitoring project. The objective of the portion described herein is to deploy a non-contact means of monitoring die cast tooling surface thermal conditions and analyzing the data in the context of the process monitor. The technical and practical challenges of developing such a non-contact thermal measurement system for continuous inspection in an industrial environment are discussed, and methods of resolving them are presented. These challenges include implementation of a wavelength filter system for quantitative determination of the surface temperature. Additionally, emissivity variations of the tooling surface as well as IR reflections are discussed. The primary issues that are addressed, however, are compensation for ambient temperature conditions and optimization of the calibration process. Other issues center on remote camera control, image acquisition, data synchronization, and data interpretation. An example application of this system, along with in-plant images and thermal data, is described.

  16. Frequency-selective absorbance detection: Refractive index and turbidity compensation with dual-wavelength measurement.

    Science.gov (United States)

    Eom, In-Yong; Dasgupta, Purnendu K

    2006-06-15

    A frequency-selective absorbance detection approach and its applications are described. First, a digital signal processor-lock-in amplifier (DSP-LIA)-based absorbance detector was evaluated. Compared to a simple operational amplifier (TL082CP)-based detector, the DSP-LIA-based detector showed lower noise levels, but the relative advantage was reduced under very low photocurrent levels (down to few nA). A 7cm pathlength flow cell with this commercial LIA-based detector exhibited excellent Beer's law linearity (r(2)=0.9999) and a noise level of 7 micro absorbance units (muAU). The limit of detection (LOD, S/N=3) for methyl orange (MO) was 7nM with this detector. Finally, as a more affordable alternative to an LIA, a balanced demodulator integrated circuit chip was used to fabricate a dual wavelength-frequency-selective LED-based absorbance detector. This device successfully compensated refractive index (RI) effect and turbidity effect in test flow systems. The LOD for MO with this system was 8nM.

  17. Dual-wavelength photoacoustic technique for monitoring tissue status during thermal treatments

    Science.gov (United States)

    Hsiao, Yi-Sing; Wang, Xueding; Deng, Cheri X.

    2013-06-01

    Photoacoustic (PA) techniques have been exploited for monitoring thermal treatments. However, PA signals depend not only on tissue temperature but also on tissue optical properties which indicate tissue status (e.g., native or coagulated). The changes in temperature and tissue status often occur simultaneously during thermal treatments, so both effects cause changes to PA signals. A new dual-wavelength PA technique to monitor tissue status independent of temperature is performed. By dividing the PA signal intensities obtained at two wavelengths at the same temperature, a ratio, which only depends on tissue optical properties, is obtained. Experiments were performed with two experimental groups, one with untreated tissue samples and the other with high-intensity focused ultrasound treated tissue samples including thermal coagulated lesion, using ex vivo porcine myocardium specimens to test the technique. The ratio of PA signal intensities obtained at 700 and 800 nm was constant for both groups from 25 to 43°C, but with distinct values for the two groups. Tissue alteration during thermal treatment was then studied using water bath heating of tissue samples from 35 to 60°C. We found that the ratio stayed constant before it exhibited a marked increase at around 55°C, indicating tissue changes at this temperature.

  18. Dual wavelength lidar observation of tropical high-altitude cirrus clouds during the ALBATROSS 1996 Campaign

    Science.gov (United States)

    Beyerle, G.; Schäfer, H.-J.; Neuber, R.; Schrems, O.; McDermid, I. S.

    Dual wavelength aerosol lidar observations of tropical high-altitude cirrus clouds were performed during the ALBATROSS 1996 campaign aboard the research vessel “POLARSTERN” on the Atlantic ocean in October-November 1996. On the basis of 57 hours of night-time observations between 23.5°N and 23.5°S we find in 72% of the altitude profiles indications of the presence of cirrus cloud layers. This percentage drops to 32% at subtropical latitudes (23.5°-30°) based on 15 hours of data. About one-half of the subtropical and tropical cirrus layers are subvisual with an optical depth of less than 0.03 at a wavelength of 532 nm. In general the clouds exhibit high spatial and temporal variability on scales of a few tens of meters vertically and a few hundred meters horizontally. No clouds are observed above the tropopause. An abrupt change in the relation between the color ratios of the parallel and perpendicular backscatter coefficients at about 240 K is interpreted in terms of changes of particle shape and/or size distribution. At temperatures between 195 and 255 K only a small fraction of the observations are consistent with the presence of small particles with dimensions of less than 0.1 µm.

  19. Using dual-wavelength, full-waveform airborne lidar for surface classification and vegetation characterization

    Science.gov (United States)

    Leigh, Holly W.; Magruder, Lori A.

    2016-10-01

    This study examines the utility of cocollected, dual-wavelength, full-waveform lidar data to characterize vegetation and landscapes through the extraction of waveform features, such as total waveform energy, canopy energy distribution, and foliage penetration metrics. Assessments are performed using data collected in May 2014 over Monterey, California, using the Chiroptera dual-laser lidar mapping system from Airborne Hydrography AB. Both full-waveform and discrete return data were collected simultaneously at green (532 nm) and near-infrared (NIR) (1064 nm) wavelengths; however, the two channels are operated independently at different pulse repetition frequencies, thus measurements are not spatially coincident. A voxelization approach is employed to generate pseudowaveforms for each wavelength along vertical columns in a regularly spaced grid, such that spectral waveform properties can be evaluated independently of spatial variations resulting from instrumentation configuration and collection scenario. The pseudowaveforms are parameterized and extracted parameters are mapped to raster layers, which are then used as inputs to a random forest classifier to predict land cover classifications across the survey area. In comparison to independent classification results for the two wavelength channels, the combination of the NIR and green response provided an improvement in overall classification accuracy of up to 6%. This effort presents the methodology associated with the voxelization approach and the exploitation of the pseudowaveform features, while illustrating a potential utility for geospatial classification using multiple wavelengths.

  20. Low-cost scheme for high-precision dual-wavelength laser metrology.

    Science.gov (United States)

    Kok, Yitping; Ireland, Michael J; Robertson, J Gordon; Tuthill, Peter G; Warrington, Benjamin A; Tango, William J

    2013-04-20

    A method capable of delivering relative optical path length metrology with nanometer precision is demonstrated. Unlike conventional dual-wavelength metrology, which employs heterodyne detection, the method developed in this work utilizes direct detection of interference fringes of two He-Ne lasers as well as a less precise stepper motor open-loop position control system to perform its measurement. Although the method may be applicable to a variety of circumstances, the specific application in which this metrology is essential is in an astrometric optical long baseline stellar interferometer dedicated to precise measurement of stellar positions. In our example application of this metrology to a narrow-angle astrometric interferometer, measurement of nanometer precision could be achieved without frequency-stabilized lasers, although the use of such lasers would extend the range of optical path length the metrology can accurately measure. Implementation of the method requires very little additional optics or electronics, thus minimizing the cost and effort of implementation. Furthermore, the optical path traversed by the metrology lasers is identical to that of the starlight or science beams, even down to using the same photodetectors, thereby minimizing the noncommon path between metrology and science channels.

  1. Mach-Zehnder modulator modulated radio-over-fiber transmission system using dual wavelength linearization

    Science.gov (United States)

    Zhu, Ran; Hui, Ming; Shen, Dongya; Zhang, Xiupu

    2017-02-01

    In this paper, dual wavelength linearization (DWL) technique is studied to suppress odd and even order nonlinearities simultaneously in a Mach-Zehnder modulator (MZM) modulated radio-over-fiber (RoF) transmission system. A theoretical model is given to analyze the DWL employed for MZM. In a single-tone test, the suppressions of the second order harmonic distortion (HD2) and third order harmonic distortion (HD3) at the same time are experimentally verified at different bias voltages of the MZM. The measured spurious-free dynamic ranges (SFDRs) with respect to the HD2 and HD3 are improved simultaneously compared to using a single laser. The output P1 dB is also improved by the DWL technique. Moreover, a WiFi signal is transmitted in the RoF system to test the linearization for broadband signal. The result shows that more than 1 dB improvement of the error vector magnitude (EVM) is obtained by the DWL technique.

  2. Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

    2013-01-01

    A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

  3. Stable Dual-Wavelength Fibre Laser with Bragg Gratings Fabricated in a Polarization-Maintaining Erbium-Doped Fibre

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; YAN Feng-Ping; MAO Xiang-Qiao; JIAN Shui-Sheng

    2008-01-01

    @@ A new polarization-independent dual-wavelength fibre laser by fabricating a uniform FBG and a chirped FBG in a polarization-maintaining erbium-doped fibre (PM-EDF) is proposed and demonstrated.The wavelength spacing is 0.18nm and the optical signal-to-noise ratio is greater than 50dB with pump power of 246mW.Chirped FBG is used to make the reflectivity wavelengths of two PM-FBGs match easier.Since both EDF and FBGs are polarization-maintaining without splices and the two wavelengths are polarization-independent, the maximum amplitude variation and wavelength shifts for both lasing wavelength with 3-min intervals over a period of six hours are less than 0.2 dB and 0.005 nm, respectively, which shows stable dual-wavelength output.

  4. Dual-wavelength Y-branch distributed Bragg reflector diode laser at 785 nanometers for shifted excitation Raman difference spectroscopy.

    Science.gov (United States)

    Maiwald, Martin; Eppich, Bernd; Fricke, Jörg; Ginolas, Arnim; Bugge, Frank; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2014-01-01

    A dual-wavelength Y-branch distributed Bragg reflector (DBR) diode laser at 785 nm is presented as an excitation light source for shifted excitation Raman difference spectroscopy (SERDS). The monolithic device was realized with deeply etched surface DBR gratings using one-step epitaxy. An optical output power of 140 mW was obtained in continuous-wave (CW) operation for each laser cavity, with emission wavelengths of the device at 784.50 and 785.12 nm. A spectral width of the laser emission of 30 pm (0.5 cm(-1)), including 95% of optical power, was measured. The mean spectral distance of both excitation lines is 0.63 nm (10.2 cm(-1)) over the whole operating range. Raman experiments using polystyrene as the test sample and ambient light as the interference source were carried out and demonstrate the suitability of the dual-wavelength diode laser for SERDS.

  5. Single- and dual-wavelength switchable erbium-doped fiber ring laser based on intracavity polarization selective tilted fiber gratings.

    Science.gov (United States)

    Mou, Chengbo; Saffari, Pouneh; Fu, Hongyan; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

    2009-06-20

    We propose and demonstrate a single- and dual-wavelength switchable erbium-doped fiber laser (EDFL) by utilizing intracavity polarization selective filters based on tilted fiber gratings (TFGs). In the cavity, one 45 degrees TFG functions as an in-fiber polarizer and the other 77 degrees TFG is used as a fiber polarization dependent loss (PDL) filter. The combined polarization effect from these two TFGs enables the laser to switch between the single- and the dual-wavelength operation with a single-polarization state at room temperature. The laser output at each wavelength shows an optical signal-to-noise ratio (OSNR) of >60 dB, a side mode suppression ratio (SMSR) of >50 dB, and a polarization extinction ratio of approximately 35 dB. The proposed EDFL can give stable output under laboratory conditions.

  6. Challenges of adapting a dual-wavelength infrared imaging system as an industrial inspection tool

    Science.gov (United States)

    Shabestari, Behrouz N.; Kourous, Helen E.; Luster, Spencer D.; Sacha, Jaroslaw P.; Graff, Stephen

    1997-09-01

    Non-contact thermal measurement techniques such as on-line thermography can be valuable tools for process monitoring and quality control. Many manufacturing processes such as welding or casting are thermally driven, or exhibit strong correlation between thermal conditions and product characteristics. Infrared inspection of self-emitted radiation can provide valuable insight into process parameters not routinely observed yet which dominate product quality. Recent advances in IR system technology coupled with significant reductions in cost are making thermography a viable tool for such on-line monitoring. This paper describes the implementation of a novel rugged thermal imaging system based on a dual-wavelength technique for a large intelligent process monitoring project. The object of the portion described herein is to deploy a non- contact means of monitoring tooling surface thermal conditions. The technical and practical challenges of developing such a non-contact thermal measurement system for continuous inspection in an industrial environment are discussed, and methods of resolving them are presented. These challenges include implementation of a wavelength filter system for quantitative determination of the surface temperature. Also, unlike visible-spectrum machine vision applications, surface emissivity of the test object as well as reflections from other IR emitters must be taken into account when measuring infrared radiation for a part or process. However, the primary issues that must be addressed prior to deployment are compensation for ambient temperature conditions and optimization of the calibration process. Other issues center on remote camera control, image acquisition, data synchronization, and data interpretation. An example application of this system, along with preliminary data, is described.

  7. Structure Measurements of Leaf and Woody Components of Forests with Dual-Wavelength Lidar Scanning Data

    Science.gov (United States)

    Strahler, A. H.; Li, Z.; Schaaf, C.; Howe, G.; Martel, J.; Hewawasam, K.; Douglas, E. S.; Chakrabarti, S.; Cook, T.; Paynter, I.; Saenz, E. J.; Wang, Z.; Woodcock, C. E.; Jupp, D. L. B.; Schaefer, M.; Newnham, G.

    2014-12-01

    Forest structure plays a critical role in the exchange of energy, carbon and water between land and atmosphere and nutrient cycle. We can provide detailed forest structure measurements of leaf and woody components with the Dual Wavelength Echidna® Lidar (DWEL), which acquires full-waveform scans at both near-infrared (NIR, 1064 nm) and shortwave infrared (SWIR, 1548 nm) wavelengths from simultaneous laser pulses. We collected DWEL scans at a broadleaf forest stand and a conifer forest stand at Harvard Forest in June 2014. Power returned from leaves is much lower than from woody materials such as trunks and branches at the SWIR wavelength due to the liquid water absorption by leaves, whereas returned power at the NIR wavelength is similar from both leaves and woody materials. We threshold a normalized difference index (NDI), defined as the difference between returned power at the two wavelengths divided by their sum, to classify each return pulse as a leaf or trunk/branch hit. We obtain leaf area index (LAI), woody area index (WAI) and vertical profiles of leaf and woody components directly from classified lidar hits without empirical wood-to-total ratios as are commonly used in optical methods of LAI estimation. Tree heights, diameter at breast height (DBH), and stem count density are the other forest structure parameters estimated from our DWEL scans. The separation of leaf and woody components in tandem with fine-scale forest structure measurements will benefit studies on carbon allocation of forest ecosystems and improve our understanding of the effects of forest structure on ecosystem functions. This research is supported by NSF grant, MRI-0923389

  8. Tunable millimeter-wave frequency synthesis up to 100 GHz by dual-wavelength Brillouin fiber laser.

    Science.gov (United States)

    Gross, Michael C; Callahan, Patrick T; Clark, Thomas R; Novak, Dalma; Waterhouse, Rodney B; Dennis, Michael L

    2010-06-21

    We demonstrate the generation of microwave and millimeter-wave frequencies from 26 to 100 GHz by heterodyning the output modes of a dual-wavelength fiber laser based on stimulated Brillouin scattering. The output frequency is tunable in steps of 10.3 MHz, equal to the free spectral range of the resonator. The noise properties of the beat frequency indicate a microwave linewidth of <2 Hz. We discuss potential for operation into the terahertz regime.

  9. Dual wavelength imaging of a scrape-off layer in an advanced beam-driven field-reversed configuration

    Science.gov (United States)

    Osin, D.; Schindler, T.

    2016-11-01

    A dual wavelength imaging system has been developed and installed on C-2U to capture 2D images of a He jet in the Scrape-Off Layer (SOL) of an advanced beam-driven Field-Reversed Configuration (FRC) plasma. The system was designed to optically split two identical images and pass them through 1 nm FWHM filters. Dual wavelength images are focused adjacent on a large format CCD chip and recorded simultaneously with a time resolution down to 10 μs using a gated micro-channel plate. The relatively compact optical system images a 10 cm plasma region with a spatial resolution of 0.2 cm and can be used in a harsh environment with high electro-magnetic noise and high magnetic field. The dual wavelength imaging system provides 2D images of either electron density or temperature by observing spectral line pairs emitted by He jet atoms in the SOL. A large field of view, combined with good space and time resolution of the imaging system, allows visualization of macro-flows in the SOL. First 2D images of the electron density and temperature observed in the SOL of the C-2U FRC are presented.

  10. Dual wavelength imaging of a scrape-off layer in an advanced beam-driven field-reversed configuration

    Energy Technology Data Exchange (ETDEWEB)

    Osin, D.; Schindler, T., E-mail: dosin@trialphaenergy.com [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688-7010 (United States)

    2016-11-15

    A dual wavelength imaging system has been developed and installed on C-2U to capture 2D images of a He jet in the Scrape-Off Layer (SOL) of an advanced beam-driven Field-Reversed Configuration (FRC) plasma. The system was designed to optically split two identical images and pass them through 1 nm FWHM filters. Dual wavelength images are focused adjacent on a large format CCD chip and recorded simultaneously with a time resolution down to 10 μs using a gated micro-channel plate. The relatively compact optical system images a 10 cm plasma region with a spatial resolution of 0.2 cm and can be used in a harsh environment with high electro-magnetic noise and high magnetic field. The dual wavelength imaging system provides 2D images of either electron density or temperature by observing spectral line pairs emitted by He jet atoms in the SOL. A large field of view, combined with good space and time resolution of the imaging system, allows visualization of macro-flows in the SOL. First 2D images of the electron density and temperature observed in the SOL of the C-2U FRC are presented.

  11. Self Powered Highly Enhanced Dual Wavelength ZnO@CdS Core-Shell Nanorod Arrays Photodetector: An Intelligent Pair.

    Science.gov (United States)

    Sarkar, Sanjit; Basak, Durga

    2015-08-01

    On the face of the impending energy crisis, developing low-energy or even zero-energy photoelectronic devices is extremely important. A multispectral photosensitivity feature of a self-powered device provides an additional powerful tool. We have developed an unprecedented high performance dual wavelength self-powered ZnO@CdS/PEDOT:PSS core-shell nanorods array photodetector through a simple aqueous chemical method wherein a suitable band alignment between an intelligent material pair, i.e. ZnO and CdS, has been utilized. Besides a noteworthy advantage of the devices being that they show a very sharp and prominent dual wavelength photosensitivity, both the ultraviolet and visible light sensitivity (ratio of current under illumination (Iphoto)/current under dark (Idark)) of the device are two orders of higher magnitude than those of pristine ZnO, attaining values of 2.8 × 10(3) and 1.07 × 10(3), respectively. At the same time, temporal responses faster than 20 ms could be achieved with these solution-processed photodetectors. The present study provides a very important direction to engineer core-shell nanostructured devices for dual wavelength high photosensitivity.

  12. In vivo glucose monitoring using dual-wavelength polarimetry to overcome corneal birefringence in the presence of motion.

    Science.gov (United States)

    Pirnstill, Casey W; Malik, Bilal H; Gresham, Vincent C; Coté, Gerard L

    2012-09-01

    Over the past 35 years considerable research has been performed toward the investigation of noninvasive and minimally invasive glucose monitoring techniques. Optical polarimetry is one noninvasive technique that has shown promise as a means to ascertain blood glucose levels through measuring the glucose concentrations in the anterior chamber of the eye. However, one of the key limitations to the use of optical polarimetry as a means to noninvasively measure glucose levels is the presence of sample noise caused by motion-induced time-varying corneal birefringence. In this article our group presents, for the first time, results that show dual-wavelength polarimetry can be used to accurately detect glucose concentrations in the presence of motion-induced birefringence in vivo using New Zealand White rabbits. In total, nine animal studies (three New Zealand White rabbits across three separate days) were conducted. Using the dual-wavelength optical polarimetric approach, in vivo, an overall mean average relative difference of 4.49% (11.66 mg/dL) was achieved with 100% Zone A+B hits on a Clarke error grid, including 100% falling in Zone A. The results indicate that dual-wavelength polarimetry can effectively be used to significantly reduce the noise due to time-varying corneal birefringence in vivo, allowing the accurate measurement of glucose concentration in the aqueous humor of the eye and correlating that with blood glucose.

  13. Tunable microwave output over a wide RF region generated by an optical dual-wavelength fiber laser

    Science.gov (United States)

    Soltanian, M. R. K.; Ahmad, H.; Pua, C. H.; Harun, S. W.

    2014-10-01

    The dual-wavelength fiber laser provides a compact, robust and stable platform for the generation of microwave signals. Two approaches towards generating microwave emissions using dual wavelengths are explored in this work, with both exploiting the heterodyning beat technique. Both approaches are based on a ring fiber laser with an erbium-doped fiber, having absorption coefficients of 16.0-20.0 dBm at 1531 nm and 11.0-13.0 dBm at 980 nm, serving as the active gain medium. A 10 cm long photonic crystal fiber with a solid core diameter of 4.37 μm and surrounded by air holes of 5.06 μm diameter with a separation of 5.52 μm between them serves to create the desired dual-wavelength output. A tunable band pass filter with bandwidth of 0.8 nm serves as a tuning mechanism together with a polarization controller. Channel spacings as narrow as 0.00043 nm can be realized, giving a microwave output of about 671.9 MHz. Furthermore, the channel spacing can be extended to as large as 0.03631 nm, giving a microwave emission in excess of 4.59 GHz. The output is highly stable, with little change in power or wavelength observed over a test period of 22 min.

  14. Stable dual-wavelength single-longitudinal-mode ring erbium-doped fiber laser for optical generation of microwave frequency

    Science.gov (United States)

    Wang, T.; Liang, G.; Miao, X.; Zhou, X.; Li, Q.

    2012-05-01

    We demonstrate a simple dual-wavelength ring erbium-doped fiber laser operating in single-longitudinal-mode (SLM) at room temperature. A pair of reflection type short-period fiber Bragg gratings (FBGs), which have two different center wavelengths of 1545.072 and 1545.284 nm, are used as the wavelength-selective component of the laser. A segment of unpumped polarization maintaining erbium-doped fiber (PM-EDF) is acted as a narrow multiband filter. By turning the polarization controller (PC) to enhance the polarization hole burning (PHB), the single-wavelength and dual-wavelength laser oscillations are observed at 1545.072 and 1545.284 nm. The output power variation is less than 0.6 dB for both wavelengths over a five-minute period and the optical signal to noise ratio (OSNR) is greater than 50 dB. By beating the dual-wavelengths at a photodetector (PD), a microwave signal at 26.44 GHz is demonstrated.

  15. Dual-wavelength single-longitudinal-mode erbium-doped fiber laser based on inverse-Gaussian apodized fiber Bragg grating and its application in microwave generation

    Science.gov (United States)

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Liang, Sheng; Hao, Jianzhong; Dong, Bo

    2011-03-01

    We propose a simple erbium-doped fiber ring laser. It consists of an inverse-Gaussian apodized fiber Bragg grating filter which has two ultra-narrow transmission bands, and an unpumped erbium-doped fiber as a saturable absorber. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength separation of approximately 0.082 nm is achieved. A microwave signal at 10.502 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  16. Comparison of Precipitation Observations from a Prototype Space-based Cloud Radar and Ground-based Radars

    Institute of Scientific and Technical Information of China (English)

    LIU Liping; ZHANG Zhiqiang; YU Danru; YANG Hu; ZHAO Chonghui; ZHONG Lingzhi

    2012-01-01

    A prototype space-based cloud radar has been developed and was installed on an airplane to observe a precipitation system over Tianjin,China in July 2010.Ground-based S-band and Ka-band radars were used to examine the observational capability of the prototype. A cross-comparison algorithm between different wavelengths,spatial resolutions and platform radars is presented.The reflectivity biases,correlation coefficients and standard deviations between the radars are analyzed.The equivalent reflectivity bias between the S- and Ka-band radars were simulated with a given raindrop size distribution.The results indicated that reflectivity bias between the S- and Ka-band radars due to scattering properties was less than 5 dB,and for weak precipitation the bias was negligible. The prototype space-based cloud radar was able to measure a reasonable vertical profile of reflectivity,but the reflectivity below an altitude of 1.5 km above ground level was obscured by ground clutter.The measured reflectivity by the prototype space-based cloud radar was approximately 10.9 dB stronger than that by the S-band Doppler radar (SA radar),and 13.7 dB stronger than that by the ground-based cloud radar.The reflectivity measured by the SA radar was 0.4 dB stronger than that by the ground-based cloud radar.This study could provide a method for the quantitative examination of the observation ability for space-based radars.

  17. Global Ka Band Broadband Satellite Services Overview (1)%全球Ka波段宽带卫星业务的现状和发展(一)

    Institute of Scientific and Technical Information of China (English)

    陈强; 赵庆锁; 李涛

    2014-01-01

    本文简要回顾了全球卫星通信从C/Ku波段到Ka波段,从话音、广播电视到互联网应用的轨迹;对目前Ka波段HTS卫星网络的架构、地面系统情况以及采用的新技术进行了概述;列出了目前全球Ka波段在轨HTS卫星、建造的HTS卫星的容量、运营公司、使用的地面系统等;介绍了美国Ka波段宽带卫星业务的发展情况。%This article is retrospected the trajectory of global satellite telecommunication industry from C/Ku band to Ka band and from Voice/TV to Internet. The article is listed in HTS satellites which are in orbit and in construction, the capacity , the operators and the ground system. The Ka band broadband satellite business in USA is also introduced.

  18. Global Ka Band Broadband Satellite Services Overview (2)%全球Ka波段宽带卫星业务的现状和发展(二)

    Institute of Scientific and Technical Information of China (English)

    陈强; 赵庆锁; 李涛

    2014-01-01

    本文简要回顾了全球卫星通信从C/Ku波段到Ka波段,从话音、广播电视到互联网应用的轨迹;对目前Ka波段HTS卫星网络的架构、地面系统情况以及采用的新技术进行了概述;并列出了目前全球Ka波段在轨HTS卫星、建造的HTS卫星的容量、运营公司、使用的地面系统等;并介绍了美国Ka波段宽带卫星业务的发展情况。%This article is retrospected the trajectory of global satellite telecommunication industry from C/Ku band to Ka band and from Voice/TV to Internet. The article is listed in HTS satellites which are in orbit and in construction, the capacity , the operators and the ground system. The Ka band broadband satellite business in USA is also introduced.

  19. Thickness and Composition Tailoring of K- and Ka-Band Microwave Absorption of BaCo x Ti x Fe(12-2 x)O19 Ferrites

    Science.gov (United States)

    Narang, Sukhleen Bindra; Pubby, Kunal; Singh, Charanjeet

    2017-02-01

    The goal of this research is to investigate the electromagnetic and microwave absorption properties of M-type barium hexaferrites with chemical formula BaCo x Ti x Fe(12-2 x)O19 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) in K and Ka band. Characterization techniques such as x-ray diffraction analysis and scanning electron microscopy were applied to confirm ferrite formation. The frequency dependence of the complex permittivity and complex permeability was studied for prepared ferrite samples in the frequency range from 18 GHz to 40 GHz. Factors such as the quarter-wavelength condition, impedance matching, high dielectric-magnetic losses, as well as ferromagnetic resonance were investigated to determine their contribution to the absorption characteristics. It was found that the quarter-wavelength ( λ/4) model could be successfully applied to predict and understand the position as well as number of reflection peaks in the microwave absorption spectrum. The origin of the reflection loss peaks is explained and verified based on calculations of input impedance, loss tangent, and ferromagnetic resonance. Reflection loss analysis revealed that all six compositions exhibited reflection loss peaks (absorption >90%) at their matching thicknesses and frequencies. Therefore, these ferrites are potential candidates for use in electromagnetic shielding applications requiring low reflectivity in K and Ka band.

  20. Design and ImpIementation of Ka-Band Up-Converer%Ka频段上变频器的设计与实现

    Institute of Scientific and Technical Information of China (English)

    王启; 陈小忠

    2015-01-01

    阐述了一种Ka频段卫星通信上变频器的实现方案,采用一次变频方案将中频信号上变频至Ka频段射频信号,在实现一定增益的同时能够保证设备的杂散、相位噪声以及幅频特性等指标。该设计方法与调试技巧能够广泛应用于卫星通信地球站的上行链路。%Describes an achievement to design a kind of Ka-band up-converter, which converts S-band IF signal to Ka-band RF signal by once frequency conversion. The some gain can be achieved as well as the output spurious, phase noise and amplitude –frequency characteristics. The design and debug method can be used in up-link of satellite communications.

  1. Rapid determination of lovastatin in the fermentation broth of Aspergillus terreus using dual-wavelength UV spectrophotometry.

    Science.gov (United States)

    Li, Shi-Weng; Song, Hong-Ping; Leng, Yan

    2014-01-01

    Lovastatin, a hypocholesterolemic drug, is produced by submerged fermentation of Aspergillus terreus Thom (Trichocomaceae). High performance liquid chromatography is usually used to determine lovastatin in samples of the fermentation broth. However, this method is inconvenient and costly, especially in the context of high-throughput sample analysis. A direct and simple dual-wavelength ultraviolet spectrophotometric method for quantifying lovastatin in the fermentation broth of A. terreus was developed. A. terreus Z15-7 was used for all experiments. The liquid fermentation was conducted at 30 °C in a rotary shaker at 150 rpm for 15 d. Silica gel and neutral alumina column chromatography were used for the separation and purification of lovastatin from the fermentation broth. The limits of detection of lovastatin were 0.320 μg/ml in the lovastatin standard solution and 0.490 μg/ml in the fermentation broth sample and the limits of quantification of lovastatin were 1.265 μg/ml in the lovastatin standard solution and 3.955 μg/ml in the fermentation broth sample. The amounts of lovastatin in the fermentation broth ranged from 876.614 to 911.967 μg/ml, with relative standard deviations from 1.203 to 1.709%. The mean recoveries of lovastatin using silica gel and neutral alumina column chromatography were 84.2 ± 0.82 and 87.2 ± 0.21%, respectively. Dual-wavelength UV spectrophotometry is a rapid, sensitive, accurate, and convenient method for quantifying lovastatin in fermentation broth. Neutral alumina column chromatography is more efficient than silica gel column chromatography for the purification and determination lovastatin using the developed dual-wavelength UV spectrophotometry method.

  2. Dual-wavelength technology used in anti-interference for long-range and short-distance detection

    Science.gov (United States)

    Zhang, Haojun; Zhao, Jianlin; Ren, Ju; Sun, Limin

    2009-10-01

    Technology of interference becomes more advancing. Adopting fog and aerosols is the best way to interfere optical detection. Due to the fog and aerosols, target recognition becomes difficult under this environment. In the present paper a method is given to solve this problem in a simple way. A dual-wavelength technology used in anti-interfere for long range and short distance detection is introduced in this paper, which can discriminate the backscattering reflection of fog and aerosols. In the present work the scattering character of the special fog and aerosols environment is calculated using the Rayleigh scattering method and Mie scattering method. The scattering characters in different environment are analyses using two wavelengths, i.e. one wavelength lies in ultraviolet wave band, the other in near infrared wave band. The results indicated that the ratio of proportion-discrimination is usually greater than 2, and deeper the strength of the fog and aerosols, the greater the ratio. This method also validated by experiment. In the present study, three kinds of wavelength such as 405nm, 670nm and 808nm are adopted. The intensity data collected shows that the ratio is greater than 3. The performance and working principle of the system and its components are analyzed in details. Based on the full system, the dual-wavelength technology can be well applied. The result of the experiments also proves that the technology is efficient, especially in the heavy fog and aerosols environment. The dual wavelength method can be used for long range and short distance detection.

  3. A Dual Wavelength Echidna® Lidar (DWEL) for Forest Structure Retrieval

    Science.gov (United States)

    Strahler, A. H.; Douglas, E. S.; Martel, J.; Cook, T.; Mendillo, C.; Marshall, R. A.; Chakrabarti, S.; Schaaf, C.; Woodcock, C. E.; Li, Z.; Yang, X.; Culvenor, D.; Jupp, D.; Newnham, G.; Lovell, J.

    2012-12-01

    A newly-constructed, ground-based lidar scanner designed for automated retrieval of forest structure, the Dual Wavelength Echidna Lidar (DWEL), separates laser "hits" of leaves from hits of trunks and branches using simultaneous laser pulses at 1548 nm, where leaf water content produces strong absorption, and at 1064 nm, where leaves and branches have similar reflectances. The DWEL uses a rotating mirror scan mechanism on a revolving mount, coupled with full digitization of return waveforms, to identify, locate, and parameterize scattering events in the three-dimensional space around the scanner. In the DWEL instrument, the two measurement lasers are triggered simultaneously. Laser pulses are sharply peaked; full-width half-max pulse length of the lasers is 5.1 ns, corresponding to 1.53 m in distance. The laser pulses are expanded and collimated to a 6-mm beam diameter (1/e2), then shaped into a top-hat cross section using a diffraction apparatus. Interchangeable optics provide a beam divergence of 1.25-, 2.5-, or 5-mrad. A mirror and two dichroic filters combine the beams and join them with a visible green continuous-wave marker laser. The combined beam is guided along an optical path to the 10-cm rotating scan mirror. Scan encoders in zenith and azimuth directions resolve the pointing of the instrument to 215 units per 2π radians. Scan resolution has three settings: 1-, 2-, and 4-mrad. Scan time varies with resolution: 11 min at 4 mrad; 41 min at 2 mrad; and 2.7 hr at 1 mrad. The return beam enters the 10-cm diameter Newtonian-Nasmyth telescope and is directed to the receiver assembly, which splits the return beam using a dichroic filter and narrowband pass filters. Two 0.5 mm InGaAs photodiodes measure the return signal, which is sampled by two digitizers at 2 gigasamples per second with 10-bit precision. This provides a 7.5-cm sampling of the 1.53 m pulse, allowing very good reconstruction of the return waveform. The designed signal-to-noise ratio is 10:1 (8

  4. Numerical Modeling of 3.5 micron Dual-Wavelength Pumped Erbium Doped Mid-Infrared Fiber Lasers

    CERN Document Server

    Malouf, Andrew; Gorjan, Martin; Ottaway, David J

    2016-01-01

    The performance of mid-infrared erbium doped fiber lasers has dramatically improved in the last few years. In this paper we present a numerical model that provides valuable insight into the dynamics of a dual-wavelength pumped fiber laser that can operate on the 3.5 micron and 2.8 micron bands. This model is a much needed tool for optimizing and understanding the performance of these laser systems. Comparisons between simulation and experimental results for three different systems are presented.

  5. Monolithic Y-branch dual wavelength DBR diode laser at 671nm for shifted excitation Raman difference spectroscopy

    Science.gov (United States)

    Maiwald, M.; Fricke, J.; Ginolas, A.; Pohl, J.; Sumpf, B.; Erbert, G.; Tränkle, G.

    2013-05-01

    A dual-wavelength laser diode source suitable for shifted excitation Raman difference spectroscopy (SERDS) is presented. This monolithic device contains two ridge waveguide (RW) sections with wavelengths adjusted distributed Bragg reflection (DBR) gratings as rear side mirrors. An integrated Y-branch coupler guides the emission into a common output aperture. The two wavelengths are centered at 671 nm with a well-defined spectral spacing of about 0.5 nm, i.e. 10 cm-1. Separate RW sections can be individually addressed by injection current. An output power up to 110 mW was achieved. Raman experiments demonstrate the suitability of these devices for SERDS.

  6. Numerical Modeling of 3.5 micron Dual-Wavelength Pumped Erbium Doped Mid-Infrared Fiber Lasers

    OpenAIRE

    Malouf, Andrew; Henderson-Sapir, Ori; Gorjan, Martin; Ottaway, David J.

    2016-01-01

    The performance of mid-infrared erbium doped fiber lasers has dramatically improved in the last few years. In this paper we present a numerical model that provides valuable insight into the dynamics of a dual-wavelength pumped fiber laser that can operate on the 3.5 micron and 2.8 micron bands. This model is a much needed tool for optimizing and understanding the performance of these laser systems. Comparisons between simulation and experimental results for three different systems are presented.

  7. A Ka-Band Transmitter for Deep Space Communication%深空通信Ka频段数传发射机的研究

    Institute of Scientific and Technical Information of China (English)

    梁显锋; 张津舟; 谢春坚; 熊蔚明; 安军社; 陈晓敏; 孙辉先

    2012-01-01

    Design of a Ka-band telemetry transmitter is proposed to meet requirements of future deep space missions. Key output characteristics results of the Ka-band transmitter are given. Integrated design and digital technologies are used to develop a light, compact and high efficiency transmitter. Based on CCSDS (Consultative Committee for Space Data Systems) recommendations, a concatenated error-control code in channel coding is used for improved performance and different code rate ranges are separately chosen for PCM/BPSK/PM (Pulse Code Modulation/ Quadrature Phase Shift Keying/Phase Modulation), NRZ (Non-Return to Zero)/BPSK and SRRC (Square Root Raised Cosine)-QPSK (Quadrature Phase Shift Keying) modulation. Equipped with an SSPA (Solid State Power Amplifier), the Ka-band transmitter provides an output power of 2. 0 W 31. 84 GHz center frequency. The supported data rate is up to 2. 0 Mbit/s with QPSK modulation.%针对我国今后深空探测任务的发展需求,提出了应用于深空通信的Ka频段数传发射机技术设计方案,给出了整机关键输出特性结果.采用一体化设计和数字化技术,Ka频段数传发射机实现了轻小型化和高效率.基于CCSDS(空间数据系统咨询委员会)的相关建议标准,信道编码采用级联纠错编码技术和低、中、高速率数传码分段对应选择PCM/BPSK/PM(脉冲编码调制/二相相移键控/调相)、NRZ/BPSK(非归零/二相相移键控)和SRRC-QPSK(平方根升余弦-四相相移键控)的数据调制模式.Ka频段发射机采用KaSSPA(Ka频段固态功率放大器)实现了在31.84 GHz中心频率输出信号功率大于2.0W,QPSK(四相相移键控)调制时支持最大码率2 Mbit/s.

  8. Single-polarization, switchable dual-wavelength erbium-doped fiber laser with two polarization-maintaining fiber Bragg gratings.

    Science.gov (United States)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Mao, Xiangqiao; Ning, Tigang; Jian, Shuisheng

    2008-08-04

    An improved erbium-doped fiber laser configuration for achieving single-polarization, switchable dual-wavelength of orthogonal polarizations oscillations at room temperature is proposed. For the first time, two fiber Bragg gratings (FBGs) directly written in a polarization-maintaining (PM) and photosensitive erbium-doped fiber (PMPEDF) as the wavelength-selective component are used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining FBG (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). Each lasing line shows a single polarization with a polarization extinction ratio of >25 dB under different pump levels. The optical signal-to-noise ratio (OSNR) is greater than 50 dB. The amplitude variation with 16 times scans in nearly one and half an hour is less than 0.5 dB at both operating wavelength.

  9. A wavelength-switchable single-longitudinal-mode dual-wavelength erbium-doped fiber laser for switchable microwave generation.

    Science.gov (United States)

    Pan, Shilong; Yao, Jianping

    2009-03-30

    A novel wavelength-switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber laser (EDFL) implemented based on a sigma architecture that is composed of a ring loop and a linear standing wave arm is experimentally demonstrated. Gain competition that prevents stable dual-wavelength oscillation is effectively suppressed by placing the gain medium in the standing-wave arm and by introducing polarization hole burning (PHB) via polarization multiplexing of the two lasing wavelengths in the ring loop. The SLM operation is guaranteed by an ultranarrow Fabry- Perot filter (FPF) introduced by absorption saturation in an unpumped erbium-doped fiber (EDF) and the gain saturation in the gain medium. In addition, the ring cavity forms a Lyot filter for each wavelength. Thus, wavelength switching is achieved by simply adjusting the polarization state of either wavelength. By beating the two SLM wavelengths at a photodetector (PD), a microwave signal with a frequency tunable from approximately 10 to approximately 50 GHz is experimentally generated.

  10. Tunable, Low Frequency Microwave Generation from AWG Based Closely-Spaced Dual-Wavelength Single Longitudinal-Mode Fibre Laser

    Science.gov (United States)

    Ahmad, H.; Latif, A. A.; Talib, J. M.; Harun, S. W.

    2013-06-01

    Stable, closely-spaced Dual-Wavelength Fibre Lasers (DWFLs) have high potential for applications such as Radio-over-Fibre and optical sensing. In this work, a DWFL using two Arrayed Waveguide Gratings (AWGs) to generate a closely-spaced dual-wavelength output is proposed and demonstrated. A 1 m long highly doped Leikki Er80-8/125 Erbium Doped Fibre (EDF) is used as the linear gain medium, while two AWGs are used to generate the closely-spaced lasing wavelengths. A Mach-Zehnder modulator, driven at 180 kHz, splits the closely spaced wavelengths into two clearly defined wavelengths, while a 7 cm long un-pumped Leikki Er80-8/125 EDF and sub-ring cavity is used to suppress unwanted side-modes. Close spacing of between 0.01 to 0.03 nm are obtained, with beating frequencies of between 1.4 to 3.2 GHz. The output is highly stable, with almost no fluctuations over the test period.

  11. On Solving TM0n Modal Excitation in a Ka-Band Overmoded Circular Waveguide by the Conservation of Complex Power Technique

    Institute of Scientific and Technical Information of China (English)

    Feng Lan; Xi Gao; Zong-Jun Shi

    2009-01-01

    To measure the radiation properties of relativistic diffraction generator (RDG) in Ka-band, a TM0n modal excitation model is established, which consists of an overmoded circular waveguide and a coaxial line feeding probe. Using the transverse E-field mode matching and the conservation of complex power technique (CCPT), we deduce the scattering matrix at coaxial line to coaxial line and coaxial line to circular waveguide junctions. Then using the overall cascaded junction scattering matrix, the numerical results for the reflection coefficient of the coaxial line and the power distribution of TM0n multi-modal are presented. The numerical results are in agreement with HFSS simulation results and experimental results. The analysis shows that by choosing the appropriate position of coaxial line probe, the power proportion of the device operating mode excited in circular waveguide could be the largest.

  12. Hardware-in-the-loop simulation of the dynamic characteristics of rain fading channel for satellite-to-Earth links at Ka-band

    Science.gov (United States)

    Yao, Hongchao; Wang, Huali

    2007-11-01

    Modeling of rain fading channel dynamics is essential to the real-time prediction of link availability for Ka-band satellite communication system under rain attenuation impairment, and can validate fade mitigation techniques (FMT) such as adaptive transmission and diversity. The mechanism of dynamic rain attenuation model based on time-series generator is firstly concerned in this paper. We further provide a scheme and implementation of real-time simulator for dynamic rain fading channels based on Hardware-in-the-loop (HIL) simulation method and general Field Programmable Logic Array (FPGA) device. Finally, the impact of adaptive modulation fade countermeasures (AMFC) in the different state of rain attenuation is evaluated with simulation results.

  13. A portable Ka-band front-end test package for beam-waveguide antenna performance evaluation. Part 1: Design and ground tests

    Science.gov (United States)

    Otoshi, T. Y.; Stewart, S. R.; Franco, M. M.

    1991-01-01

    A unique experimental method was used to test the beam waveguide (BWG) antenna at Deep Space Station (DDS) 13 in the Goldstone Deep Space Communications Complex near Barstow, California. The methodology involved the use of portable test packages to make measurements of operating noise temperatures and antenna efficiencies (as functions of antenna pointing angles) at the Cassegrain focal point and the final focal point located in a subterranean pedestal room. Degradations caused by the BWG mirror systems were determined by making comparisons of the measured parameters at the two focal points of the antenna. Previous articles were concerned with the design, performance characteristics, and test results obtained with an X-band test package operating at 32 GHz. Noise temperature measurement results are presented for the Ka-band test package in an on-the-ground test configuration.

  14. The Electron Gun's Design with High Performance for Ka-Band TWT%Ka波段行波管高性能电子枪设计

    Institute of Scientific and Technical Information of China (English)

    赵国庆; 王文祥; 宫玉彬; 魏彦玉; 黄民智

    2012-01-01

    The initial structure parameters of the electron gun for Ka-band TWT can be obtained by the synthesis iteration proposed by Vaughan, and then, the modifications for electron gun's structure are performed by stimulation and optimization with the TAU. With comparison of the uniformity electron's emission density of the cathode surface, the influence of trajectories for different thermal emission angles of e-lectrons, the trajectory's laminar and the radial current density distribution near the electron beam's waist, the final structure of the electron gun is got. The test result is in agreement with the optimized design for Ka-band TWT electron gun.%利用学者Vaughan等提出的皮尔斯电子枪设计综合迭代法计算得到某Ka波段行波管电子枪的基本结构参数;在此基础上,采用电子光学数值模拟软件Tau进行模拟优化进一步修改电子枪各结构尺寸;在模拟优化过程中,通过量化比较、判断阴极表面电子发射密度的均匀性,比较阴极表面部分热初速电子非垂直发射时对电子注轨迹的影响程度,比较注腰位置附近电子注层流性及径向密度分布均匀性等,最后得到优化的电子枪结构设计.对装配有此优化设计电子枪的行波管进行了实验研究,测试结果达到设计要求.

  15. Realization of Stable Narrow Linewidth Dual-Wavelength Lasing in an Erbium-Doped Fibre Laser by Cleaving the Wavelength-Selective Filter Spectrum

    Institute of Scientific and Technical Information of China (English)

    JIA Xiu-Jie; LIU Yan-Ge; SI Li-Bin; GUO Zhan-Cheng; FU Sheng-Gui; LIU Feng-Nian; YUAN Shu-Zhong; DONG Xiao-Yi

    2006-01-01

    @@ We propose and demonstrate a new concept of stable narrow-line-width and close wavelength spacing dual-wavelength lasing in an Er-doped fibre ring laser (EDFRL) by cleaving the spectrum with a wavelength-selective component in the EDFRL. A fibre loop mirror (FLM) combining with a polarization controller (PC) acts as the cleaver. The cleaver can produce a fine pectinate spectrum. By adjusting the PC, the fine pectinate spectrum can be so changeable that cleaving the spectrum of a fibre Bragg grating (FBG) into two parts. As a result, we obtain the dual-wavelength fibre lasering with a bandwidth of only 0.03nm and a wavelength spacing of only 0.07 nm. Furthermore, the laser can also perform stable switchable single wavelength or stable different-bandwidth dual-wavelength by carefully adjusting the PC at room temperature.

  16. Simultaneous emission of Gaussian-like and parabolic-like pulse waveforms in an erbium-doped dual-wavelength fiber laser.

    Science.gov (United States)

    Li, Xing; Dai, Shenggan; Zou, Weiwen; Chen, Jianping; Nie, Qiuhua; Dai, Shixun

    2017-08-25

    We report on the observation of different pulse formation dynamics in a nonlinear polarization evolution (NPE)-based broadband erbium-doped fiber laser when the net cavity group-velocity dispersion (GVD) is managed to be close to zero. The fiber laser can generate pulses with a single wavelength or dual wavelengths by adjusting the waveplates. When the laser operates in dual-wavelength emission, the output pulses corresponding to the two wavelengths exhibit Gaussian- and parabolic-like waveforms, respectively, indicating that the laser can simultaneously operate in stretched-pulse and self-similar regimes. The generation of dual-wavelength emission with different pulse waveforms can be attributed to an overdriven NPE switch acting on a chirped broadband pulse and different dispersion mechanisms. These findings provide a good foundation for comprehensively studying pulse formation dynamics in laser cavities.

  17. Photonic generation of microwave signal using a dual-wavelength erbium-doped fiber ring laser with CMFBG filter and saturable absorber

    Science.gov (United States)

    Feng, Suchun; Lu, Shaohua; Peng, Wanjing; Li, Qi; Qi, Chunhui; Feng, Ting; Jian, Shuisheng

    2013-02-01

    A simple approach for photonic generation of microwave signal using a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser is proposed and demonstrated. For the first time as we know, a chirped moiré fiber Bragg grating (CMFBG) filter with ultra-narrow transmission band and a chirped fiber Bragg grating (FBG) are used to select the laser longitudinal mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter and 3 m unpumped EDF acting as a saturable absorber. Stable dual-wavelength SLM fiber laser with a wavelength spacing of approximately 0.140 nm is experimentally realized. By beating the dual-wavelength fiber laser at a photodetector, photonic generation of microwave signal at 17.682 GHz is successfully obtained.

  18. Characterization of Topography and Vegetation Structure using Dual-wavelength LIDAR and High-Resolution Stereo Imagery

    Science.gov (United States)

    Leigh, H. W.; Magruder, L. A.; Neuenschwander, A. L.

    2015-12-01

    This study examines the utility of co-collected, dual-wavelength, full-waveform LIDAR and high resolution stereo imagery to improve characterizations of topography and vegetation over two survey sites near Monterey, CA. Extraction of waveform features, such as total waveform energy, canopy energy distribution, and foliage penetration metrics are computed along the laser line-of-sight and along the vertical axis of synthesized "pseudowaveforms." The pseudowaveform technique is a novel method that allows for direct comparisons between green (532nm) and near IR (1064nm) waveforms, despite variations in sampling. Comparisons between wavelengths allows for detailed characterization of vegetation structure and distribution not possible with single-wavelength LIDAR. Additionally, point clouds derived from stereo imagery are fused with LIDAR point clouds to increase resolution and improve accuracy of bare earth digital elevation models, further augmenting characterization of tree height and structure.

  19. Dual-wavelength nano-engineered Thulium-doped fiber laser via bending of singlemode-multimode-singlemode fiber structure

    Science.gov (United States)

    Zulkifli, A. Z.; Latiff, A. A.; Paul, M. C.; Yasin, M.; Ahmad, H.; Harun, S. W.

    2016-12-01

    In this paper, a dual-wavelength fiber laser (DWFL) using nano-engineered Thulium-doped fiber as a gain medium with a bent singlemode-multimode-singlemode fiber structure (SMS) is demonstrated. The SMS structure is packaged systematically using Cr-39 polymer plates to provide linear bending via applied load. Experimental results have proved that the bent SMS is capable to provide highly effective wavelength filter and wavelengths stabilizer by balancing the net cavity gain between the two wavelengths. The DWFL provides very narrow spacing of 0.9 nm, narrow 3 dB spectral linewidth of ∼0.07 nm and SNR of ∼42 dB. Based on stability test, very small mode hopping is observed at the two wavelengths having deviations of ±0 nm and ±0.04 nm respectively. In conjunction, the DWFL provides very stable relative wavelength spacing with a deviation of ±0.04 nm.

  20. Development of an ultra-widely tunable DFG-THz source with switching between organic nonlinear crystals pumped with a dual-wavelength BBO optical parametric oscillator.

    Science.gov (United States)

    Notake, Takashi; Nawata, Kouji; Kawamata, Hiroshi; Matsukawa, Takeshi; Qi, Feng; Minamide, Hiroaki

    2012-11-01

    We developed a difference frequency generation (DFG) source with an organic nonlinear optical crystal of DAST or BNA selectively excited by a dual-wavelength β-BaB(2)O(4) optical parametric oscillator (BBO-OPO). The dual-wavelength BBO-OPO can independently oscillate two lights with different wavelengths from 800 to 1800 nm in a cavity. THz-wave generation by using each organic crystal covers ultrawide range from 1 to 30 THz with inherent intensity dips by crystal absorption modes. The reduced outputs can be improved by switching over the crystals with adequately tuned pump wavelengths of the BBO-OPO.

  1. Low Timing Jitter and Tunable Dual- Wavelength Picosecond Pulse Genera from a Fabry-Pérot Laser Diode with External Injection

    Institute of Scientific and Technical Information of China (English)

    YANG Yi-Biao; WANG Yun-Cai; ZHANG Ming-Jiang; LIANG Wei

    2007-01-01

    A novel scheme to generate tunable dual-wavelength optical pulses with low timing jitter at arbitrary repetition rates is proposed and demonstrated experimentally. The pulses are generated from a gain-switched Fabry-Perot laser diode with two external cw beams for injection seeding simultaneously. The cw light is generated by two independent distributed feedback laser diodes, and their wavelengths can be tuned independently by two temperature controllers. The dual-wavelength pulses with the pulse width of 57 ps, the timing jitter of 340 fs, are obtained. The sidemode-suppression ratio of the output pulses is better than 23 dB over a 10-nm wavelength tuning range.

  2. Diode-pumped passively dual-wavelength Q-switched Nd:GYSGG laser using graphene oxide as the saturable absorber.

    Science.gov (United States)

    Song, Qi; Wang, Guoju; Zhang, Bingyuan; Wang, Wenjun; Wang, Minghong; Zhang, Qingli; Sun, Guihua; Bo, Yong; Peng, Qinjun

    2015-04-01

    The performance of a diode end-pumped passively Q-switched dual-wavelength Nd:GYSGG laser operating at 1057.28 and 1060.65 nm with graphene oxide as the saturable absorber was demonstrated. The maximum dual-wavelength average output power of 521 mW was achieved under the absorbed pump power of 5.4 W, corresponding to the optical-to-optical conversion and slope efficiency of 9.8% and 21%, respectively. The minimum pulse width was 115 ns with a pulse repetition rate of 338 kHz.

  3. LD end-pumped acousto-optic Q-switched 1319 nm/1338 nm dual-wavelength Nd:YAG laser

    Science.gov (United States)

    Wu, C. T.; Yu, M.; Wang, C.; Yu, K.; Yu, Y. J.; Chen, X. Y.; Jin, G. Y.

    2016-10-01

    Laser characteristics of acousto-optic Q-switched operation of 1319 nm/1338 nm dual-wavelength composite Nd:YAG laser were studied. Maximum output power of 5.77 W was achieved in CW operation. Under Q-switched operation, the maximum peak power of 3.96 kW and minimum pulse width of 65.6 ns was obtained at repetition frequency of 20 kHz with the duty ratio of 96%. The influence of the duration of the ultrasonic field acted on the Q-switch to the output characteristics of dual-wavelength composite Nd:YAG laser had been reported first time.

  4. Experiment Study of Dual Wavelength and Dual Pulse Q-switched Intracavity Frequency Doubling of a Tunable Cr:LiSAF Laser

    Institute of Scientific and Technical Information of China (English)

    CHEN Changshui; WANG Peilin; XIE Jianping; SHI Dufang; SHA Xianwu; HE Yulong

    2001-01-01

    In this paper, a flashlamp-pumped Q-switched Cr: LiSAF laser system with intracavity frequency doubling is designed to obtain dual pulse and dual wavelength laser output. The behaviors of second harmonic output of dual pulse and dual wavelength are studied experimentally. Good results are obtained in experiments: the output energy of each second harmonic pulse a round 448.1 nm is 10.2 mJ, the dual pulse time interval can be tuned widely, and the tunable range of each second harmonic wavelength is 448.1 to 465 nm.

  5. Radar altimetry backscattering signatures at Ka, Ku, C, and S bands over West Africa

    Science.gov (United States)

    Frappart, F.; Fatras, C.; Mougin, E.; Marieu, V.; Diepkilé, A. T.; Blarel, F.; Borderies, P.

    This study presents a comprehensive comparison of radar altimetry signatures at Ka-, Ku-, C-, and S-bands using SARAL, ENVISAT and Jason-2 data over the major bioclimatic zones, soil and vegetation types encountered in West-Africa, with an emphasis on the new information at Ka-band provided by the recently launched SARAL-Altika mission. Spatio-temporal variations of the radar altimetry responses were related to changes in surface roughness, land cover and soil wetness. Analysis of time series of backscattering coefficients along the West African bioclimatic gradient shows that radar echoes at nadir incidence are well correlated to soil moisture in semi-arid savannah environments. Radar altimeters are able to detect the presence of water even under a dense canopy cover at all frequencies. But only measurements at Ka-band are able to penetrate underneath the canopy of non-inundated tropical evergreen forests.

  6. Ka波段螺旋波纹波导回旋行波管%Linear calculation of Ka-band gyro-TWT with helical waveguide

    Institute of Scientific and Technical Information of China (English)

    薛智浩; 刘濮鲲; 杜朝海

    2012-01-01

    螺旋波纹波导回旋行波管与采用圆波导的回旋行波管相比,有较大的带宽.介绍了它的线性注波互作用理论,并用该理论计算了不同的磁场与波导表面微扰幅度对Ka波段螺旋波纹波导回旋行渡管线性增益的影响.计算结果与已报道的实验结果基本符合,说明该理论可以初步确定螺旋波纹波导回旋行波管的各项参数.%Gyrotron traveling-wave tube (gyro-TWT) with helical waveguide has wider instantaneous frequency bandwidth than that with smooth waveguide. This paper introduces the linear theory of its beam-wave interaction, and calculates the influence on linear gain of Ka-band gyro-TWT caused by changing the applied magnetic field and the amplitude of the groove. The results accord with those reported, indicating that the theory can be used to preliminarily determine the parameters of gyro-TWT assembly.

  7. A Compact Ka-Band PHEMT MMIC Voltage Controlled Oscillator%紧凑型Ka波段PHEMT微波单片集成VCO

    Institute of Scientific and Technical Information of China (English)

    余稳; 孙晓玮; 钱蓉; 张义门

    2005-01-01

    设计并流片制作了基于GaAs PHEMT工艺的Ka波段微波单片集成压控振荡器(MMIC VCO).该VCO具有紧凑、宽电调谐带宽及高输出功率的特点.提出了缩小芯片面积及增大调谐带宽的方法,同时还给出了设计MMIC VCO的基本步骤.该方法设计并流片制做的MMIC VCO的测量结果为:振荡频率为36±1.2GHz,输出功率为10士1dBm,芯片面积为1.3mm×1.0mm.%A compact Ka-band monolithic microwave integrated circuit(MMIC) voltage controlled oscillator (VCO)with wide tuning range and high output power, which is based on GaAs PHEMT process,is presented. A method is introduced to reduce the chip size and to increase the bandwidth of operation. The procedure to design a MMIC VCO is also described here. The measured oscillating frequency of the MMIC VCO is 36±1.2GHz and the output power is 10±1dBm. The fabricated MMIC chip size is 1.3mm× 1.0mm.

  8. Application of Synthetic Storm Technique for Diurnal and Seasonal Variation of Slant Path Ka-Band Rain Attenuation Time Series over a Subtropical Location in South Africa

    Directory of Open Access Journals (Sweden)

    J. S. Ojo

    2015-01-01

    Full Text Available As technology advances and more demands are on satellite services, rain-induced attenuation still creates one of the most damaging effects of the atmosphere on the quality of radio communication signals, especially those operating above 10 GHz. System designers therefore require statistical information on rain-induced attenuation over the coverage area in order to determine the appropriate transmitter and receiver characteristics to be adopted. This paper presents results on the time-varying rain characterization and diurnal variation of slant path rain attenuation in the Ka-band frequency simulated with synthetic storm techniques over a subtropical location in South Africa using 10-year rain rate time-series data. The analysis is based on the CDF of one-minute rain rate; time-series seasonal variation of rain rate observed over four time intervals: 00:00–06:00, 06:00–12:00, 12:00–18:00, and 18:00–24:00; diurnal fades margin; and diurnal variation of rain attenuation. Comparison was also made between the synthesized values and measured attenuation data. The predicted statistics are in good agreement with those obtained from the propagation beacon measurement in the area. The overall results will be needed for an acceptable planning that can effectively reduce the fade margin to a very low value for an optimum data communication over this area.

  9. Review of the Airborne Ku and Ka-band Satellite Communication System%机载Ku、Ka频段卫星通信系统综述

    Institute of Scientific and Technical Information of China (English)

    艾文光; 赵大勇; 邓军

    2011-01-01

    叙述了Ku频段和Ka频段机载卫星通信系统的国内外发展现状,列举了几个典型的卫星通信系统技术指标,并简述了研制机载卫星通信系统应注意的事项和技术途径,其中包括选择天线系统形式,合理分配系统指标,消除多普勒效应的影响等。%This paper reviews the Ku-band and Ka-band airborne satellite communication system both at home and abroad,cites a few typical satellite communication system specifications,and outlines matters that deserve our attention and some technical approaches in the development of airborne satellite communications systems,including choosing the form of antenna system,reasonably allocating system indicators,and eliminating the impact of the Doppler effect.

  10. A Frequency Transfer and Cleanup System for Ultra-High Stability at Both Long and Short Times for the Cassini Ka-Band Experiment

    Science.gov (United States)

    Calhoun, M. D.; Dick, G. J.; Wang, R. T.

    1999-01-01

    New radio science experiments, including a gravitational wave search and several atmospheric occultation studies, are planned for the Cassini Ka-band experiment. These experiments are made possible by reduced solar-induced phase fluctuations at the high-frequency (32 GHZ) of the radio link between the earth and the spacecraft. In order to match the improved link performance, a significant upgrade is under way to improve the frequency stability capabilities of NASA's Deep Space Network (DSN). Significant improvements are being undertaken in many areas, including antenna vibration and (wet) tropospheric calibration, in addition to frequency generation and distribution. We describe here the design and development of a system to provide a reference signal with the highest possible frequency stability for both long-term, short-term, and phase noise, at an antenna (DSS 25) that is remote from the frequency standards room at SPC-10 at the Goldstone site. The new technologies were developed in order to meet the very tight requirements. They are: 1) a Stabilized Fiber-Optic Distribution Assembly (SFODA) that includes active compensation of thermal variations to transfer long-term stability over 16 km of ordinary fiber-optic cable, and 2) a Compensated Sapphire Oscillator (CSO) that provides short-term performance in a cryocooled sapphire oscillator with ultra-high short-term stability and low phase noise.

  11. A low-phase-noise Ka-band push-push voltage-controlled oscillator using CMOS/glass-integrated passive device technologies.

    Science.gov (United States)

    Wang, Sen

    2014-09-01

    In this paper, a Ka-band CMOS push-push voltage- controlled oscillator (VCO) integrated into a glass-integrated passive device (GIPD) process is presented. The transformer, λ/4 transmission line, and inductors of the VCO are realized in the GIPD process, achieving superior performances, and therefore improve the phase noise of the VCO. Moreover, the transformer-based VCO is a differential Hartley topology to further reduce the phase noise and chip area. Operating at 1.8 V supply voltage, the VCO core consumes merely 3.8 mW of dc power. The measured phase noise is -109.18 dBc/Hz at 1 MHz offset from the 30.84 GHz oscillation frequency. The push-push VCO also demonstrates a 24.5 dB fundamental rejection, and exhibits an 8.4% tuning range. Compared with recently published CMOS-based VCOs, it is observed that the proposed VCO exhibits excellent performance under low power consumption.

  12. Lunar Noise-Temperature Increase Measurements at S-Band, X-Band, and Ka-Band Using a 34-Meter-Diameter Beam-Waveguide Antenna

    Science.gov (United States)

    Morabito, D. D.

    2006-08-01

    The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will cause an increase in receiver noise temperature that needs to be accounted for in telemetry, radio science, or ranging link budgets. The Deep Space Network may be required to use its antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature increase as a function of observing frequency, lunar phase, and angular offset of the antenna beam from the center of the lunar disk. This article quantifies such a set of measurements acquired at DSS 13, a 34-m-diameter research and development beam-waveguide antenna located at Goldstone, California, at three different telecommunication frequencies, S-band (2.3 GHz), X-band (8.4 GHz), and Ka-band (32 GHz), over a wide range of lunar phase, for both disk-centered and limb-centered positions of the antenna beam.

  13. Generation of dual-wavelength square pulse in a figure-eight erbium-doped fiber laser with ultra-large net-anomalous dispersion.

    Science.gov (United States)

    Shao, Zhihua; Qiao, Xueguang; Rong, Qiangzhou; Su, Dan

    2015-08-01

    A type of wave-breaking-free mode-locked dual-wavelength square pulse was experimentally observed in a figure-eight erbium-doped fiber laser with ultra-large net-anomalous dispersion. A 2.7 km long single-mode fiber (SMF) was incorporated as a nonlinear optical loop mirror (NOLM) and provided largely nonlinear phase accumulation and anomalous dispersion, which enhanced the four-wave-mixing effect to improve the stability of the dual-wavelength operation. In the NOLM, the long SMF with small birefringence supported the Sagnac interference as a filter to manage the dual-wavelength lasing. The dual-wavelength operation was made switchable by adjusting the intra-cavity polarization loss and phase delay corresponding to two square pulses. When the pump power was increased, the duration of the square pulse increased continuously while the peak pulse power gradually decreased. This square-type pulse can potentially be utilized for signal transmission and sensing.

  14. Lidar Observations of Tropical High-altitude Cirrus Clouds: Results form Dual Wavelength Raman Lidar Measurements During the ALBATROSS Campaign 1996

    Science.gov (United States)

    Neuber, R.; Wegener, Alfred; Schrems, O.; McDermid, I. S.

    1997-01-01

    Results from dual wavelength Raman Lidar Observations of tropical high-altitude cirrus clouds are reported. Based on 107 hours of night-time measurements cirrus cloud were present in more than 50% of the observations at latitudes between 23.5 degress S and 23.5 degrees N and altitudes between 11 and 16km.

  15. Lidar Observations of Tropical High-altitude Cirrus Clouds: Results form Dual Wavelength Raman Lidar Measurements During the ALBATROSS Campaign 1996

    Science.gov (United States)

    Neuber, R.; Wegener, Alfred; Schrems, O.; McDermid, I. S.

    1997-01-01

    Results from dual wavelength Raman Lidar Observations of tropical high-altitude cirrus clouds are reported. Based on 107 hours of night-time measurements cirrus cloud were present in more than 50% of the observations at latitudes between 23.5 degress S and 23.5 degrees N and altitudes between 11 and 16km.

  16. Investigations of radicular dentin permeability and ultrastructural changes after irradiation with Er,Cr:YSGG laser and dual wavelength (2780 and 940 nm) laser.

    Science.gov (United States)

    Al-Karadaghi, Tamara Sardar; Franzen, Rene; Jawad, Hussein A; Gutknecht, Norbert

    2015-11-01

    The aim of this study was to assess the effectiveness of dual wavelength (2780 nm Er,Cr:YSGG, 940 nm diode) laser in elimination of smear layer comparing it with Er,Cr:YSGG laser in terms of radicular dentin permeability and ultrastructural changes of root canal walls. Fifty-one sound single-rooted extracted teeth were instrumented up to size F4 and divided into three groups: group Co, non-irradiated samples; group A, irradiated with Er,Cr:YSGG laser; group B, irradiated with the dual wavelength laser. Afterward, the roots were made externally impermeable, filled with 2% methylene blue dye, divided horizontally into three segments reflecting the cervical, middle, and apical thirds then examined under microscope. Using analytical software, the root section area and dye penetration area were measured, and then, the percentage of net dye penetration area was calculated. Additionally, scanning electron microscope investigations were accomplished. Analysis of variance (ANOVA) showed significant differences between all groups over the three root thirds. Dye permeation in dual wavelength laser group was significantly higher over the whole root length: cervical, middle, and apical compared to Er,Cr:YSGG laser group and non-irradiated samples (p laser root canal irradiation produced uneven removal of smear layer, in efficient cleanliness especially in the apical third. There was no sign of melting and carbonization. Within the studied parameters, root canal irradiation with dual wavelength laser increased dentin permeability.

  17. A C- and L-band dual-wavelength erbium-doped fibre laser for assisting four-wave mixing self-stability

    Science.gov (United States)

    Liu, Xueming; Zhao, Wei; Liu, Hongjun; Zou, Kuaisheng; Zhang, Tongyi; Lu, Keqing; Sun, Chuandong; Wang, Yishan; Ouyang, Xian; Chen, Guofu; Hou, Xun

    2006-06-01

    A kind of photonic 'Robin Hood' based on four-wave mixing is proposed and proved to be effective, theoretically and experimentally, in detail. Its applications for L-band dual-wavelength erbium-doped fibre (EDF) laser use are experimentally demonstrated at room temperature. The experimental results show that the conventional EDF cavity only induces a very unstable L-band laser, but the novel Robin Hood can effectively suppress the homogeneous gain in the erbium laser. By using suitable fibre Bragg gratings and stretching them, the proposed EDF laser can operate from ~1520 to ~1635 nm, so our dual-wavelength EDF laser can be used in lasing operation not only for the L band but also for the C band. The outstanding merits of our dual-wavelength laser are the flexible tuning and the ultrabroad spectral range of more than 115 nm. The experimental results show that the stability and uniformity of the proposed dual-wavelength laser in C-band operation are better than those for the same laser in L-band operation.

  18. Dual-wavelength high-power diode laser system based on an external-cavity tapered amplifier with tunable frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    A dual-wavelength high-power semiconductor laser system based on a tapered amplifier with double-Littrow external cavity is demonstrated around 800 nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 10.0 THz. To our knowle...

  19. Realization of modulating broadband emission from Er-Tm codoped calcium boroaluminate glasses by dual-wavelength pumping

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingzhu; Lu, Fang [State Key Laboratory of Surface Physics and of Micro and Nano Photonic Structure (Ministry of Education), Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Xu, Fei, E-mail: drfeixu@gmail.com [SHU-SolarE R and D Lab, Department of Physics, College of Sciences, Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China); Jiang, Zuimin; Wang, Xiao; Lou, Haonan [State Key Laboratory of Surface Physics and of Micro and Nano Photonic Structure (Ministry of Education), Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Ma, Zhongquan; Zheng, Lingling [SHU-SolarE R and D Lab, Department of Physics, College of Sciences, Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China)

    2012-11-15

    Near-infrared photoluminescence (PL) of calcium boroaluminate (CABAL) glasses codoped with Er{sub 2}O{sub 3} and Tm{sub 2}O{sub 3} has been investigated by dual-wavelength pumping at 795 and 476 nm. Spectrum shape of broadband emission could be modulated by controlling the power ratio of two pumping lines (P{sub 476}/P{sub 795}). The result shows that the full width at half maximum can reach {approx}500 nm in the wavelength range from 1.3 to 2.0 {mu}m by controlling P{sub 476}/P{sub 795} = 12. The PL spectra show four characteristic peaks located at 1.46, 1.53, 1.58 and 1.80 {mu}m, corresponding to Tm{sup 3+}: {sup 3}H{sub 4} {yields} {sup 3}F{sub 4}, Er{sup 3+}: {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2}, Tm{sup 3+}: {sup 1}G{sub 4} {yields} {sup 3}F{sub 2} and Tm{sup 3+}: {sup 3}F{sub 4} {yields} {sup 3}H{sub 6} emissions, respectively. The energy transfer (ET) (ET1: Er{sup 3+}: {sup 4}I{sub 13/2}, Tm{sup 3+}: {sup 3}F{sub 4} {yields} Er{sup 3+}: {sup 4}I{sub 15/2}, Tm{sup 3+}: {sup 3}H{sub 4} and ET2: Er{sup 3+}: {sup 4}I{sub 13/2}, Tm{sup 3+}: {sup 3}H{sub 6} {yields} Er{sup 3+}: {sup 4}I{sub 15/2}, Tm{sup 3+}: {sup 3}F{sub 4}) between Er{sup 3+} and Tm{sup 3+} ions play important roles in the luminescence mechanisms. In addition, a new ET process (ET: Tm{sup 3+}: {sup 1}G{sub 4}, Er{sup 3+}: {sup 4}F{sub 9/2} {yields} Tm{sup 3+}: {sup 3}F{sub 2}, Er{sup 3+}: {sup 4}F{sub 7/2}) was identified. The flat broadband emission with the bandwidth of {approx}500 nm could be realized by changing P{sub 476}/P{sub 795} as a result of the radiative transitions, Tm-Tm cross-relaxation (Tm{sup 3+}: {sup 3}H{sub 4}, {sup 3}H{sub 6} {yields} Tm{sup 3+}: {sup 3}F{sub 4}, {sup 3}F{sub 4}) and Er-Tm ET processes. -- Highlights: Black-Right-Pointing-Pointer Dual-wavelength pumping has been applied to modulate broadband emission in rare-earth-doped materials. Black-Right-Pointing-Pointer It is easier to control the pumping source than the concentration of sample for modulating

  20. All-fiber dual-wavelength Q-switched and mode-locked EDFL by SMF-THDF-SMF structure as a saturable absorber

    Science.gov (United States)

    Latiff, A. A.; Kadir, N. A.; Ismail, E. I.; Shamsuddin, H.; Ahmad, H.; Harun, S. W.

    2017-04-01

    We demonstrate all-fiber dual-wavelength Q-switched and mode-locked erbium-doped fiber laser (EDFL) by utilizing the thulium-holmium-doped fiber (THDF) as a fiber saturable absorber (SA) and also a Mach-Zehnder interferometer (MZI) element. The 19 cm long THDF has a core diameter of 11.5 μm, refractive index difference of 0.005, and cutoff wavelength of 1810 nm. Stable dual-wavelength Q-switching operation was generated at 1555.14 nm and 1557.64 nm with free spectral range (FSR) of 2.5 nm. The repetition rate of 14.45-78.49 kHz was obtained between 12 and 100 mW pump power. At maximum pump power, the maximum output power and pulse energy were 2.58 mW and 32.87 nJ, respectively. By adding 195 cm long SMF in the same cavity, the stable dual-wavelength mode-locking operation was started at 166 mW and continue stable to 201 mW pump power. This mode-locking operation produced stable dual-wavelength pulses at 1530.34 nm and 1532.84 nm with a repetition rate of 1 MHz with a pulse duration of 128 ns and signal-to-noise ratio (SNR) of 62 dB. It shares the same value of FSR in Q-switching operation. The highest output power of 1.57 nJ corresponds to the maximum output power of 1.57 mW was obtained. Our results validate the linear absorption characteristic at C-band region and multimode fiber effect of THDF can be utilized as SA to generate stable all-fiber dual-wavelength pulsed lasers. Remarkably, these findings expand a fiber gain medium application in short pulse generation.

  1. 双波长视网膜血氧测量系统%Dual-wavelength Retinal Oximeter

    Institute of Scientific and Technical Information of China (English)

    先永利; 戴云; 高椿明; 杜睿

    2016-01-01

    In order to measure retinal oxygen saturation, a dual-wavelength retinal oximeter based on commercial fundus camera was designed. The system made the retinal image of the commercial fundus camera second imaging, and simultaneously collected dual-wavelength images that respectively represented the same absorption coefficient wavelength images and the different one of oxygenated hemoglobin and de-oxygenated hemoglobin. The retinal oxygen saturation was finally measured after image registration, vessel segmentation and calculation of optic density ratio of the two images. The means oxygen saturation of artery and venules in health human for repeated measurements were 92.85% and 56.75%, respectively.The mean standard deviation was 2.41% for arterioles and 3.63% for venules.The data demonstrate that the system is reliable and reproducible. The system can obtain retinal structural imaging, which provides a useful tool for research of life sciences and diagnosis of retinal-related diseases.%为了测量视网膜血氧饱和度,本文设计一种以商业眼底相机为平台的双波长视网膜血氧测量系统。该系统将商业眼底相机输出的视网膜像进行二次成像,同时采集含氧血红蛋白和还原血红蛋白的等吸收波段和非等吸收波段图像。对获取的双波长图像进行图像配准、血管分割、光密度比计算等一系列运算,最终完成视网膜血管血氧饱和度的测量。对健康人眼进行重复性测量,动脉和静脉的血氧饱和度平均值分别是92.85%和56.75%,标准差的平均值分别为2.41%和3.63%,表明系统的准确性和重复性较好。本系统在获取视网膜结构图像的同时获得视网膜血管功能信息,可以为生命科学相关研究、眼底相关疾病的诊断提供有力工具。

  2. The Envelope and Embedded Disk around the Class 0 Protostar L1157-mm: Dual-wavelength Interferometric Observations and Modeling

    CERN Document Server

    Chiang, Hsin-Fang; Tobin, John J

    2012-01-01

    We present dual-wavelength observations and modeling of the nearly edge-on Class 0 young stellar object L1157-mm. Using the Combined Array for Research in Millimeter-wave Astronomy, a nearly spherical structure is seen from the circumstellar envelope at the size scale of 10^2 to 10^3 AU in both 1 mm and 3 mm dust emission. Radiative transfer modeling is performed to compare data with theoretical envelope models, including a power-law envelope model and the Terebey-Shu-Cassen model. Bayesian inference is applied for parameter estimation and information criteria is used for model selection. The results prefer the power-law envelope model against the Terebey-Shu-Cassen model. In particular, for the power-law envelope model, a steep density profile with an index of ~2 is inferred. Moreover, the dust opacity spectral index (beta) is estimated to be ~0.9, implying that grain growth has started at L1157-mm. Also, the unresolved disk component is constrained to be < 40 AU in radius and < 4-25 M_Jup in mass. How...

  3. Dual-wavelength excited photoluminescence spectroscopy of deep-level hole traps in Ga(In)NP

    Energy Technology Data Exchange (ETDEWEB)

    Dagnelund, D.; Huang, Y. Q.; Buyanova, I. A.; Chen, W. M. [Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping (Sweden); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, La Jolla, CA 92093 (United States); Yonezu, H. [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan)

    2015-01-07

    By employing photoluminescence (PL) spectroscopy under dual-wavelength optical excitation, we uncover the presence of deep-level hole traps in Ga(In)NP alloys grown by molecular beam epitaxy (MBE). The energy level positions of the traps are determined to be at 0.56 eV and 0.78 eV above the top of the valance band. We show that photo-excitation of the holes from the traps, by a secondary light source with a photon energy below the bandgap energy, can lead to a strong enhancement (up to 25%) of the PL emissions from the alloys under a primary optical excitation above the bandgap energy. We further demonstrate that the same hole traps can be found in various MBE-grown Ga(In)NP alloys, regardless of their growth temperatures, chemical compositions, and strain. The extent of the PL enhancement induced by the hole de-trapping is shown to vary between different alloys, however, likely reflecting their different trap concentrations. The absence of theses traps in the GaNP alloy grown by vapor phase epitaxy suggests that their incorporation could be associated with a contaminant accompanied by the N plasma source employed in the MBE growth, possibly a Cu impurity.

  4. Simple and Specific Dual-Wavelength Excitable Dye Staining for Glycoprotein Detection in Polyacrylamide Gels and Its Application in Glycoproteomics

    Directory of Open Access Journals (Sweden)

    Yu-Hsuan Chiang

    2011-01-01

    Full Text Available In this study, a commercially available fluorescent dye, Lissamine rhodamine B sulfonyl hydrazine (LRSH, was designed to specifically stain the glycoproteins in polyacrylamide gels. Through the periodate/Schiff base mechanism, the fluorescent dye readily attaches to glycoproteins and the fluorescence can be simultaneously observed under either 305 nm or 532 nm excitation therefore, the dye-stained glycoproteins can be detected under a regular UV transilluminator or a more elegant laser-based gel scanner. The specificity and detection limit were examined using a standard protein mixture in polyacrylamide gels in this study. The application of this glycoprotein stain dye was further demonstrated using pregnancy urine samples. The fluorescent spots were further digested in gel and their identities confirmed through LC-MS/MS analysis and database searching. In addition, the N-glycosylation sites of LRSH-labeled uromodulin were readily mapped via in-gel PNGaseF deglycosylation and LC-MS/MS analysis, which indicated that this fluorescent dye labeling does not interfere with enzymatic deglycosylation. Hence, the application of this simple and specific dual-wavelength excitable dye staining in current glycoproteome research is promising.

  5. Dual Wavelength RP-HPLC Method for Simultaneous Determination of Two Antispasmodic Drugs: An Application in Pharmaceutical and Human Serum

    Directory of Open Access Journals (Sweden)

    Najmul Hasan

    2013-01-01

    Full Text Available A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v, at flow rate 1.0 mL/min using a Hibar μBondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation. Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimethylphloroglucinol. The method was validated in accordance with ICH guidelines and was applied successfully to quantify the amount of trimethylphloroglucinol and phloroglucinol in bulk, injectable form and physiological fluid. Forced degradation studies proved the stability indicating abilities of the method.

  6. Photoacoustic imaging of a near-infrared fluorescent marker based on dual wavelength pump-probe excitation

    Science.gov (United States)

    Märk, Julia; Theiss, Christoph; Schmitt, Franz-Josef; Laufer, Jan

    2014-03-01

    Photoacoustic imaging has been used to determine the spatial distribution of fluorophores, such as exogenous dyes and genetically expressed proteins, from images acquired in phantoms and in vivo. Most methods involve the acquisition of multiwavelength images and rely on differences in the absorption spectra of the tissue chromophores to estimate the spatial distribution and abundance of the latter using spectral decomposition techniques, such as model based inversion schemes. However, the inversion of 3-D images can be computationally expensive. Experimental approaches to localising contrast agents may therefore be useful, especially if quantification is not essential. This work aims to develop a method for determining the spatial distribution of a near-infrared fluorescent cell marker from images acquired using dual wavelength excitation. The excitation wavelengths coincided with the absorption and emission spectrum of the fluorophore. The contrast mechanism relies on reducing the excited state lifetime of the fluorophore by inducing stimulated emission. This changes the amount of energy thermalized by the fluorophore, and hence the photoacoustic signal amplitude. Since this is not observed in endogenous chromophores, the background may be removed by subtracting two images acquired with and without pulse delay between the pump and probe pulses. To characterise the fluorophore, the signal amplitude is measured in a cuvette as a function of pulse delay, concentration, and fluence. The spatial distribution of the fluorophore is determined from images acquired in realistic tissue phantoms. This method may be suitable for in vivo applications, such as imaging of exogenous or genetically expressed fluorescent cell markers.

  7. [Simultaneous determination of cobalt and nickel in catalyst by microwave digestion-dual wavelength equal absorption spectrophotometry].

    Science.gov (United States)

    Li, L; Zhang, J; Gao, C

    2001-08-01

    Catalyst samples are digested in a microwave digestion system. The optimum parameters for microwave digestion are selected. Cobalt and nickel in the mixture of Co2+ and Ni2+ with 4-(2-pyridylazo) resorcinol (PAR) can be determined simultaneously by dual-wavelength equal absorption spectrophotometry. By means of the combination of two methods, Co2+ and Ni2+ in catalyst can be determined rapidly, accurately, and contamination problems avoided. The linear ranges are 0-30 micrograms.25 mL-1 for Co2+ and 0-25 micrograms.25 mL-1 for Ni2+. The recoveries of Co2+ and Ni2+ in synthetic samples are between 98.2%-103.6% and between 97.9%-103.7%, respectively. The relative standard deviations of analytical results in catalyst samples are less than 2.2% for Co2+ and less than 1.8% for Ni2+, and relative errors are less than +/- 2.5% for Co2+ and Ni2+.

  8. 785-nm dual wavelength DBR diode lasers and MOPA systems with output powers up to 750 mW

    Science.gov (United States)

    Sumpf, Bernd; Maiwald, Martin; Klehr, Andreas; Müller, André; Bugge, Frank; Fricke, Jörg; Ressel, Peter; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Shifted excitation Raman difference spectroscopy (SERDS), i.e. exciting the sample alternatingly with two slightly shifted wavelengths, allows to distinguish between the Raman lines and sources of interference. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers and their application in master oscillator power amplifier (MOPA) systems at 785 nm suitable for Raman spectroscopy and SERDS will be presented. The definition of the wavelengths is made by implementing deeply-etched 10th order 500 μm long surface gratings with different periods using i-line wafer stepper lithography. Y-branch DBR lasers with a total length of 3 mm and a stripe width of 2.2 μm were manufactured and characterized. The monolithic devices reach output powers up to 215 mW with emission widths of about 20 pm. At 200 mW the conversion efficiency is 20%, i.e. the electrical power consumption is only 1 W. The spectral distance between the two laser cavities is about 0.6 nm, i.e. 10 cm-1 as targeted. The side mode suppression ratio is better than 50 dB. Amplifying these devices using a ridge waveguide amplifier an output power of about 750 mW could be achieved maintaining the spectral properties of the master oscillator.

  9. Single-mode SOA-based 1kHz-linewidth dual-wavelength random fiber laser.

    Science.gov (United States)

    Xu, Yanping; Zhang, Liang; Chen, Liang; Bao, Xiaoyi

    2017-07-10

    Narrow-linewidth multi-wavelength fiber lasers are of significant interests for fiber-optic sensors, spectroscopy, optical communications, and microwave generation. A novel narrow-linewidth dual-wavelength random fiber laser with single-mode operation, based on the semiconductor optical amplifier (SOA) gain, is achieved in this work for the first time, to the best of our knowledge. A simplified theoretical model is established to characterize such kind of random fiber laser. The inhomogeneous gain in SOA mitigates the mode competition significantly and alleviates the laser instability, which are frequently encountered in multi-wavelength fiber lasers with Erbium-doped fiber gain. The enhanced random distributed feedback from a 5km non-uniform fiber provides coherent feedback, acting as mode selection element to ensure single-mode operation with narrow linewidth of ~1kHz. The laser noises are also comprehensively investigated and studied, showing the improvements of the proposed random fiber laser with suppressed intensity and frequency noises.

  10. THE ENVELOPE AND EMBEDDED DISK AROUND THE CLASS 0 PROTOSTAR L1157-mm: DUAL-WAVELENGTH INTERFEROMETRIC OBSERVATIONS AND MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Hsin-Fang; Looney, Leslie W. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Tobin, John J., E-mail: hchiang@ifa.hawaii.edu [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

    2012-09-10

    We present dual-wavelength observations and modeling of the nearly edge-on Class 0 young stellar object L1157-mm. Using the Combined Array for Research in Millimeter-wave Astronomy, a nearly spherical structure is seen from the circumstellar envelope at the size scale of 10{sup 2}-10{sup 3} AU in both 1 mm and 3 mm dust emission. Radiative transfer modeling is performed to compare data with theoretical envelope models, including a power-law envelope model and the Terebey-Shu-Cassen model. Bayesian inference is applied for parameter estimation and information criterion is used for model selection. The results prefer the power-law envelope model against the Terebey-Shu-Cassen model. In particular, for the power-law envelope model, a steep density profile with an index of {approx}2 is inferred. Moreover, the dust opacity spectral index {beta} is estimated to be {approx}0.9, implying that grain growth has started at L1157-mm. Also, the unresolved disk component is constrained to be {approx}<40 AU in radius and {approx}<4-25 M{sub Jup} in mass. However, the estimate of the embedded disk component relies on the assumed envelope model.

  11. Design of a Novel Ka-band Circular Polarization Microstrip Antenna%一种新型Ka频段圆极化微带天线设计

    Institute of Scientific and Technical Information of China (English)

    刘洋; 王昕; 董涛

    2012-01-01

    A novel Ka band circular-polarization microstrip antenna is proposed.The antenna is coupled-fed by L-shaped apertures in the ground plane to realize circular-polarization.The antenna array is analyzed and optimized,then the array is made and measured.Simulated and measured results show the feasibility of the proposed design.Simulated results of the relative impedance bandwidth and axial-ratio bandwidth are 3.9% and 2% respectively,and measured results are 4.2% and 3.5%.With good circular polarization performance,the antenna can be used in satellite communication.%提出了一种Ka频段圆极化微带天线的新设计,采用缝隙耦合馈电方式,通过在接地板开L型缝隙实现天线的圆极化工作。对天线阵列进行了仿真优化和加工实测,仿真和测试结果表明了设计的可行性。天线仿真和实测的相对阻抗带宽分别为3.9%和4.2%,仿真和实测的轴比相对带宽分别为2%和3.5%。天线具有良好的圆极化特性,可应用在卫星通信中。

  12. Ka频段遥感卫星数据接收系统跟踪性能测试新方法%A New Tracking Performance Test Method for Ka-band Remote Sensing Satellite Data Receiving System

    Institute of Scientific and Technical Information of China (English)

    朱维祥; 穆伟; 王万玉; 冯旭祥; 王永华

    2015-01-01

    To solve the problems in the tracking performance test of Ka-band Low Earth Orbit( LEO) re-mote sensing satellite data receiving system,a new method is proposed. Simulation data is generated by u-sing Ka-band LEO satellite,and dynamic target tracking is simulated with the method of tracking Ka-band beacon on the calibration tower by rotating the third axis of antenna. A verification test on tracking per-formance of receiving system is carried out in the developed prototype system. The proposed method pro-vides a reference for acceptance test for Ka-band LEO satellite data receiving system.%针对Ka频段低轨遥感卫星数据接收系统跟踪性能测试中的问题,提出了一种新的测试方法。利用设计的Ka频段低轨卫星动态目标模拟数据,采用转动第三轴跟踪标校塔Ka频段信标的方式模拟动态目标的跟踪,在研制的原型系统中开展了接收系统跟踪性能的测试验证。该测试方法可为Ka频段低轨卫星数据接收系统跟踪性能的测试验收提供参考。

  13. Room-temperature dual-wavelength erbium-doped fibre laser based on a sampled fibre Bragg grating and a photonic Robin Hood

    Science.gov (United States)

    Liu, Xueming; Zhao, Wei; Lu, Keqing; Zhang, Tongyi; Sun, Chuandong; Wang, Yishan; Hou, Xun; Chen, Guofu

    2006-12-01

    With the assistance of a kind of photonic Robin Hood that is originated from four-wave mixing in a dispersion-flattened high-nonlinearity photonic-crystal fibre, a novel dual-wavelength erbium-doped fibre (EDF) laser is proposed and demonstrated by using a sampled fibre Bragg grating. The experiments show that, due to the contribution of the photonic Robin Hood, the proposed fibre laser has the advantage of excellent uniformity, high stability and stable operation at room temperature. Our dual-wavelength EDF laser has the unique merit that the wavelength spacing remains unchanged when tuning the two wavelengths of laser, and this laser is simpler and more stable than the laser reported by Liu et al. [Opt. Express, 13 142 (2005)].

  14. Tunable continuous-wave dual-wavelength laser by external-cavity superluminescent diode with a volume Bragg grating and a diffraction grating

    Science.gov (United States)

    Zheng, Yujin; Kurita, Takashi; Sekine, Takashi; Kato, Yoshinori; Kawashima, Toshiyuki

    2016-10-01

    We demonstrate the tunable continuous-wave dual-wavelength laser based on a double external-cavity superluminescent diode (SLD). The double external cavity consisted of a volume Bragg grating (VBG) and a diffraction grating bracketing the SLD's two facets. The VBG was used as an output coupler to enable the external-cavity SLD to achieve a stable wavelength. A narrow bandwidth of 0.25 nm was achieved in single-wavelength operation. The diffraction grating served as an end mirror to create another tunable wavelength external cavity for the SLD. A wavelength tuning range of 23 nm was achieved. The laser output of the double external-cavity SLD had a tunable spectral separation with dual-wavelengths from +6.42 to -16.94 nm. An output power of up to 37.7 mW was achieved with a frequency difference of 7.1 THz.

  15. 2-μm switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect

    Science.gov (United States)

    Wang, Shun; Lu, Ping; Zhao, Shui; Liu, Deming; Yang, Wei; Zhang, Jiangshan

    2014-06-01

    We demonstrated a 2-μm switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect. Few-mode fiber-embedded Sagnac ring configuration and a Mach-Zehnder interferometer are cascaded to form a multiwavelength filter for our previous 2-μm fiber laser. By adopting suitable fiber length and adjusting the polarization controller, we obtained a 2-μm dual-wavelength fiber laser with switchable wavelength interval. Experimental results revealed that the proposed laser shows higher quality and better stability compared with our previous work and it has potential applications in the fields of atmospheric propagation and microwave photonics.

  16. A geomorphologist's dream come true: synoptic high resolution river bathymetry with the latest generation of airborne dual wavelength lidar

    Science.gov (United States)

    Lague, Dimitri; Launeau, Patrick; Michon, Cyril; Gouraud, Emmanuel; Juge, Cyril; Gentile, William; Hubert-Moy, Laurence; Crave, Alain

    2016-04-01

    Airborne, terrestrial lidar and Structure From Motion have dramatically changed our approach of geomorphology, from low density/precision data, to a wealth of data with a precision adequate to actually measure topographic change across multiple scales, and its relation to vegetation. Yet, an important limitation in the context of fluvial geomorphology has been the inability of these techniques to penetrate water due to the use of NIR laser wavelengths or to the complexity of accounting for water refraction in SFM. Coastal bathymetric systems using a green lidar can penetrate clear water up to 50 m but have a resolution too coarse and deployment costs that are prohibitive for fluvial research and management. After early prototypes of narrow aperture green lidar (e.g., EEARL NASA), major lidar manufacturer are now releasing dual wavelength laser system that offer water penetration consistent with shallow fluvial bathymetry at very high resolution (> 10 pts/m²) and deployment costs that makes the technology, finally accessible. This offers unique opportunities to obtain synoptic high resolution, high precision data for academic research as well as for fluvial environment management (flood risk mapping, navigability,…). In this presentation, we report on the deployment of the latest generation Teledyne-Optech Titan dual-wavelength lidar (1064 nm + 532 nm) owned by the University of Nantes and Rennes. The instrument has been deployed over several fluvial and lacustrine environments in France. We present results and recommendation on how to optimize the bathymetric cover as a function of aerial and aquatic vegetation cover and the hydrology regime of the river. In the surveyed rivers, the penetration depth varies from 0.5 to 4 m with discrete echoes (i.e., onboard detection), heavily impacted by water clarity and bottom reflectance. Simple post-processing of the full waveform record allows to recover an additional 20 % depth. As for other lidar techniques, the main

  17. A novel mobile dual-wavelength laser altimetry system for improved site-specific Nitrogen fertilizer applications

    Science.gov (United States)

    Eitel, J.; Magney, T. S.; Vierling, L. A.; Brown, T. T.; Huggins, D. R.

    2012-12-01

    Reducing fertilizer inputs while maintaining yield would increase farmer's profits and similarly lessen the adverse environmental effects of production agriculture. The development of technologies that allow precise, site-specific application of Nitrogen (N) fertilizer has thus been an important research goal over the past decades. Remote sensing of foliar crop properties and function with tractor-mountable optical sensors has thought to be useful to optimize N fertilizer applications. However, on-the-go sensing of foliar crop properties and function has proven difficult, particularly during early crop growth stages when fertilizer decisions are often made. This difficulty arises from the fact that the spectral signal measured by on-the-go sensors is dominated by soil reflectance during early crop growth stages. Here, we present the basic principles behind a novel, dual-wavelength, tractor mountable laser altimetry system that measures the laser return intensity of the reflected green and red laser light. The green (532 nm) and the red (660 nm) wavelength combination allows calculation of a modified Photochemical Reflectance Index (mPRI) that have shown to be sensitive to both crop function and foliar chemistry. The small field of view of the laser points (diameter: 4 mm) combined with its high sampling rate (1000 points sec-1) allows vegetation returns to be isolated from ground returns by using simple thresholds. First tests relating foliar N of winter wheat (Triticum aestivum L.) with laser derived mPRI are promising (r2 = 0.72). Further research is needed to test the relationship between laser derived spectral indices and crop function.

  18. Switchable Dual-Wavelength Mode-Locked Er-Doped Fibre Laser Using a Bragg Grating in Polarization-Maintaining Fibre

    Institute of Scientific and Technical Information of China (English)

    FENG Xin-Huan; LIU Yan-Ge; SUN Lei; XIONG Ling-Yun; LI-Yao; YUAN Shu-Zhong; KAI Gui-Yun; DONG Xiao-Yi

    2004-01-01

    @@ A simple actively mode-locked fibre ring laser is proposed and successfully demonstrated to generate switchable dual-wavelength picosecond pulses using a Bragg grating in a polarization-maintaining fibre. The wavelength spacing specified by the grating is only 0.52nm. The proposed laser can be made to operate in stable dualwavelength or switch between wavelengths at room temperature, only by simple adjustment of a polarization controller.

  19. Fan tomography of the tropospheric water vapor for the calibration of the Ka band tracking of the Bepi-Colombo spacecraft (MORE experiment).

    Science.gov (United States)

    Barriot, Jean-Pierre; Serafini, Jonathan; Sichoix, Lydie

    2012-07-01

    The radiosciences Bepi-Colombo MORE experiment will use X/X, X/Ka and Ka/Ka band radio links to make accurate measurements of the spacecraft range and range rate. Tropospheric zenith wet delays range from 1.5 cm to 10 cm, with high variability (less than 1000 s) and will impair these accurate measurements. Conditions vary from summer (worse) to winter (better), from day (worse) to night (better). These wet delays cannot be estimated from ground weather measurements and alternative calibration methods should be used in order to cope with the MORE requirements (no more than 3 mm at 1000 s). Due to the Mercury orbit, MORE measurements will be performed by daylight and more frequently in summer than in winter (from Northern hemisphere). Two systems have been considered to calibrate this wet delay: Water Vapour Radiometers (WVRs) and GPS receivers. The Jet Propulsion Laboratory has developed a new class of WVRs reaching a 5 percent accuracy for the wet delay calibration (0.75 mm to 5 mm), but these WVRs are expensive to build and operate. GPS receivers are also routinely used for the calibration of data from NASA Deep Space probes, but several studies have shown that GPS receivers can give good calibration (through wet delay mapping functions) for long time variations, but are not accurate enough for short time variations (100 to 1000 s), and that WVRs must be used to efficiently calibrate the wet troposphere delays over such time spans. We think that such a calibration could be done by assimilating data from all the GNSS constellations (GPS, GLONASS, Galileo, Beidou and IRNSS) that will be available at the time of the Bepi-Colombo arrival at Mercury (2021), provided that the underlying physics of the turbulent atmosphere and evapotranspiration processes are properly taken into account at such time scales. This implies to do a tomographic image of the troposphere overlying each Deep Space tracking station at time scales of less than 1000 s. For this purpose, we have

  20. 一种Ka波段低噪声下变频器组件%Novel Ka-band low-noise down-converter assembly

    Institute of Scientific and Technical Information of China (English)

    李鸣; 李兴国

    2006-01-01

    An efficient way to design a down-converter assembly for the Ka-band millimeter system is presented, in which dielectric resonators (DR's) are adopted in the Schottky barrier diode image recovery mixer and the local oscillator (LO). DR structures guarantee high frequency stability with an acceptable volume. The configurations of low noise amplifier, mixer and oscillator in the assembly are described and fabricated to estimate the chain performance. According to the verification results, the assembly exhibits the noise figure of less than 5 dB over 1 GHz frequency range, and the single-sideband phase noise (200 kHz offset from carrier frequency) of - 70 dBc/Hz. Utilizing the DR structure, the frequency stability of the local oscillator is less than 60 × 10-6/℃.%介绍了一种用于毫米波系统的下变频器,其中混频器采用了肖特基二极管镜频回收混频结构,振荡器采用了DRO(dielectric resonator oscillator)结构以提高系统性能,以保证在合适的体积内实现较高的频率稳定度.描述了系统中低噪声放大器、混频器、振荡器的性能,用于评估系统链路性能,最后合并制作在单个基片上.根据测试结果,该下变频器的噪声系数在35 GHz处1 GHz频率范围内小于5 dB,单边带相位噪声系数在偏离载波200 kHz处达到-70 dBc/Hz.由于采用了介质谐振结构,本振的频率稳定度小于60×10-6/℃.

  1. Compact High-Repetition-Rate Monochromatic Terahertz Source Based on Difference Frequency Generation from a Dual-Wavelength Nd:YAG Laser and DAST Crystal

    Science.gov (United States)

    Zhong, Kai; Mei, Jialin; Wang, Maorong; Liu, Pengxiang; Xu, Degang; Wang, Yuye; Shi, Wei; Yao, Jianquan; Teng, Bing; Xiao, Yong

    2017-01-01

    Although high-repetition-rate dual-wavelength Nd:YAG lasers at 1319 and 1338 nm have been realized for quite a long time, we have employed it in generating monochromatic terahertz (THz) wave in this paper for the first time. The dual-wavelength laser was LD-end-pumped and acousto-optically (AO) Q-switched with the output power of watt level operating at different repetition rates from 5.5 to 30 kHz. Using a 0.6-mm-thick organic nonlinear crystal DAST for difference frequency generation (DFG), a compact terahertz source was achieved at 3.28 THz. The maximum average output power was about 0.58 μW obtained at a repetition rate of 5.5 kHz, corresponding to the conversion efficiency of about 6.4 × 10-7. The output power scaling is still feasible with higher pump power and a longer nonlinear DFG crystal. Owing to the compactness of the dual-wavelength laser and the nonlinear crystal, a palm-top terahertz source is expected for portable applications such as imaging and so on.

  2. Switchable 10 nm-spaced dual-wavelength SLM fiber laser with sub-kHz linewidth and high OSNR using a novel multiple-ring configuration

    Science.gov (United States)

    Feng, Ting; Ding, Dongliang; Zhao, Ziwei; Su, Hongxin; Yan, Fengping; Yao, X. Steve

    2016-10-01

    A switchable dual-wavelength (10 nm spacing) single-longitudinal-mode (SLM) erbium-doped fiber laser (EDFL) that uses a multiple-ring configuration was demonstrated experimentally. A novel theoretically lossless triple-ring passive secondary cavity composed of three optical couplers was utilized to select the SLM from the dense main cavity longitudinal modes for the first time. Using two superimposed fiber Bragg gratings as one compact mode-restricting element and introducing the nonlinear polarization rotation effect to alleviate the strong mode competition for the fiber laser, a highly stable dual-wavelength mode-hop-free SLM operation with sub-kHz linewidths and optical signal to noise ratios (OSNRs) of  >69 dB was achieved for both lasing wavelengths. By adjusting the polarization controllers, the dual-wavelength operation could be easily switched to single-wavelength lasing with a linewidth of  72 dB. The proposed EDFL may find many important applications, such as the generation of very pure terahertz waves.

  3. 2-μm Switchable dual-wavelength single-longitudinal-mode fiber laser based on a core-offset structure and carbon nanotube

    Science.gov (United States)

    Chen, Enci; Lu, Ping; Yang, Wei; Liu, Deming; Zhang, Jiangshan

    2016-11-01

    In this paper, we demonstrate a switchable single-longitudinal-mode (SLM) dual-wavelength fiber laser in 2-μm region based on a core-offset structure and carbon nanotube (CNT). The switchability of the fiber laser is based on a core-offset structure which acts as a tunable filter, so that the laser can work in stable dual-wavelength operation or switch between two wavelengths by adjusting the curvature of the core-offset structure. 3.68 nm (1919.44-1923.12 nm) and 6.32 nm (1890.64-1896.96 nm) tuning range can be obtained by tuning FBGs, respectively. The wavelength shift is less than 0.08 nm, and the power variation is smaller than 0.5 and 1 dB at 1923 and 1897 nm, respectively. The SLM oscillation is guaranteed by the CNT, which works as the loss factor to realize SLM oscillation. Absorption of the CNT increases the lasing threshold of the laser, therefore only the stronger mode can get lasing and SLM emission can be obtained. The proposed fiber laser offers a convenient and low-cost design for switchable dual-wavelength fiber laser in 2-μm region which has potential application in fields of gas sensing, lidar, and so on.

  4. Highly sensitive liquid-level sensor based on dual-wavelength double-ring fiber laser assisted by beat frequency interrogation.

    Science.gov (United States)

    Dai, Yi; Sun, Qizhen; Tan, Sisi; Wo, Jianghai; Zhang, Jiejun; Liu, Deming

    2012-12-01

    A highly sensitive liquid-level sensor based on dual-wavelength single-longitudinal-mode fiber laser is proposed and demonstrated. The laser is formed by exploiting two parallel arranged phase-shift fiber Bragg gratings (ps-FBGs), acting as ultra-narrow bandwidth filters, into a double-ring resonators. By beating the dual-wavelength lasing output, a stable microwave signal with frequency stability better than 5 MHz is obtained. The generated beat frequency varies with the change of dual-wavelength spacing. Based on this characteristic, with one ps-FBG serving as the sensing element and the other one acting as the reference element, a highly sensitive liquid level sensor is realized by monitoring the beat frequency shift of the laser. The sensor head is directly bonded to a float which can transfer buoyancy into axial strain on the fiber without introducing other elastic elements. The experimental results show that an ultra-high liquid-level sensitivity of 2.12 × 10(7) MHz/m within the measurement range of 1.5 mm is achieved. The sensor presents multiple merits including ultra-high sensitivity, thermal insensitive, good reliability and stability.

  5. A fiber laser pumped dual-wavelength mid-infrared laser based on optical parametric oscillation and intracavity difference frequency generation

    Science.gov (United States)

    Wang, Peng; Shang, Yaping; Li, Xiao; Shen, Meili; Xu, Xiaojun

    2017-02-01

    We report a dual-wavelength mid-infrared laser based on intracavity difference frequency generation (DFG) in an MgO-doped periodically poled LiNbO3, which was pumped by a dual-wavelength fiber MOPA consisting of two parts: a dual-wavelength seed and a power amplifier. The maximum pump power was 74.1 W and the wavelengths were 1060 nm and 1090 nm. The wavelengths of the mid-infrared output were 3.1 µm and 3.4 µm under maximum pump power with a total idler power of 6.57 W. The corresponding pump-to-idler slope efficiency reached 12%. The contrast for the peak intensity of the emissions for the two idlers was 0.6. A power preamplifier was added in a further experiment to enhance the contrast. The idler output reached 4.45 W under the maximum pump power of 70 W, which was lower than before. However, the contrast for the idler emission peak intensity was increased to 1.18. The signal wave generated in the experiment only had a single wavelength around 1.6 µm, indicating that two kinds of nonlinear processes occurred in the experiment, namely optical parametric oscillation and intracavity DFG.

  6. Evaluation of dual-wavelength excitation autofluorescence imaging of colorectal tumours with a high-sensitivity CMOS imager: a cross-sectional study.

    Science.gov (United States)

    Kominami, Yoko; Yoshida, Shigeto; Tanaka, Shinji; Miyaki, Rie; Sanomura, Yoji; Seo, Min-Woong; Kagawa, Keiichiro; Kawahito, Shoji; Arimoto, Hidenobu; Yamada, Kenji; Chayama, Kazuaki

    2015-09-02

    It is important to devise efficient and easy methods of detecting colorectal tumours to reduce mortality from colorectal cancer. Dual-wavelength excitation autofluorescence intensity can be used to visualize colorectal tumours. Therefore, we evaluated dual-wavelength excitation autofluorescence images of colorectal tumours obtained with a newly developed, high-sensitivity complementary metal-oxide-semiconductor (CMOS) imager. A total 107 colorectal tumours (44 adenomas, 43 adenocarcinomas with intramucosal invasion, and 20 sessile serrated adenoma/polyps [SSA/Ps]) in 98 patients who underwent endoscopic tumour resection were included. The specimens were irradiated with excitation light at 365 nm and 405 nm, and autofluorescence images measured with a 475 ± 25-nm band pass filter were obtained using a new, high-sensitivity CMOS imager. Ratio images (F365ex/F405ex) were created to evaluate the lesion brightness compared with that of normal mucosa, and specimens were categorized into a no signal or high signal group. Adenomas and adenocarcinomas were depicted in 87 ratio images, with 86.2% (n = 75) in the High signal group. SSA/P was depicted in 20 ratio images, with 70.0% (n = 14) in the High signal group. Dual-wavelength excitation autofluorescence images of colorectal tumours can be acquired using our high-sensitivity CMOS imager, and are useful in detecting colorectal tumours.

  7. Switchable dual-wavelength single-longitudinal-mode erbium-doped fiber laser using an inverse-Gaussian apodized fiber Bragg grating filter and a low-gain semiconductor optical amplifier.

    Science.gov (United States)

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Hao, Jianzhong; Dong, Bo; Liang, Sheng

    2010-12-20

    We present a stable and switchable dual-wavelength erbium-doped fiber laser. In the ring cavity, an inverse-Gaussian apodized fiber Bragg grating serves as an ultranarrow dual-wavelength passband filter, a semiconductor optical amplifier biased in the low-gain regime reduces the gain competition of the two wavelengths, and a feedback fiber loop acts as a mode filter to guarantee a stable single-longitudinal-mode operation. Two lasing lines with a wavelength separation of approximately 0.1 nm are obtained experimentally. A microwave signal at 12.51 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  8. Smart antennas for space-borne synthetic aperture radars

    Science.gov (United States)

    Qin, F.; Gao, S.; Mao, C.; Wang, Z.; Patyuchenko, A.; Younis, M.; Krieger, G.

    2015-11-01

    This paper discusses smart antennas for space-borne synthetic aperture radar (SAR). First, some recent development in smart antennas for space-borne SAR is reviewed. Then, the paper presents a low-cost space-borne SAR system using digital beam forming on receive. The smart antenna system is also discussed, and some results are shown. The antenna system, consisting of a parabolic reflector and multi-feed array, is designed and optimized for dual-band dual-polarized digital beam-forming performance. The operating frequencies are at X and Ka bands with the center frequency of 9.6 and 35.75 GHz, respectively. The stacked dipoles and square patches with parasitic elements are employed as the feed elements at X and Ka bands. Dual-band antenna arrays are combined in the same aperture, which not only reduce the aperture of the feed array, but also coincide the center of dual-band feed arrays.

  9. Evaluation of Temperature Elevation During Root Canal Treatment with Dual Wavelength Laser: 2780 nm Er,Cr:YSGG and 940 nm Diode.

    Science.gov (United States)

    Al-Karadaghi, Tamara Sardar; Gutknecht, Norbert; Jawad, Hussein A; Vanweersch, Leon; Franzen, Rene

    2015-09-01

    The purpose of this study was to evaluate the effects of dual wavelength (2780 nm Er,Cr:YSGG and 940 nm diode) laser with radial firing tip (RFT) on the external root surface and sub-surfaces, in terms of temperature changes during laser-assisted root canal treatment. A significant factor that may limit the use of lasers in endodontics is the possible thermal injury to tooth supporting structures. A total of 50 sound single-rooted extracted teeth were divided randomly into two groups (n = 25). Group A, irradiated with Er,Cr:YSGG laser at 1.06 W, 50 Hz, and 50 μs was a control group, and group B was irradiated with dual wavelength of Er,Cr:YSGG laser with the same settings as group A and a diode laser of 0.51 W at 4 ms and 10 ms pulse duration. K-type thermocouples were used to record temperature changes at the cervical, middle, and apical root thirds, on root surfaces and sub-surfaces, arising from delivery of laser energy through RFT. Temperature elevation in group B was significantly higher in the middle and apical thirds of the prepared samples than in group A (p surface region corresponding to a 1.48 mm dentin thickness, whereas a mean temperature increase of 7.72°C was recorded corresponding to dentin thickness of 0.95 mm. Within the studied parameters, the dual wavelength laser did not result in adverse thermal changes on the external root surface in vitro.

  10. HfO{sub 2}/SiO{sub 2} multilayer enhanced aluminum alloy-based dual-wavelength high reflective optics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Angela Q. [Johns Hopkins University, The Zanvyl Krieger School of Arts and Sciences, Baltimore, MD 21218 (United States); Corning Advanced Optics, Fairport, NY 14450-1376 (United States); Wang, Jue [Corning Advanced Optics, Fairport, NY 14450-1376 (United States); D' lallo, Michael J.; Platten, Jim E. [Corning Advanced Optics, Fairport, NY 14450-1376 (United States); Crifasi, Joseph C.; Roy, Brian P. [Corning Advanced Optics, Keene, NH 03431 (United States)

    2015-10-01

    Laser durable multiband high reflective optics can be attained by depositing HfO{sub 2}/SiO{sub 2} stacks on diamond-turned and optically polished aluminum alloy substrates. HfO{sub 2} and SiO{sub 2} single layers were prepared using modified plasma-ion assisted deposition. Ellipsometric measurements were performed using two types of variable angle spectroscopic ellipsometry with a combined spectral range of 150 nm to 14 μm. Optical constants were generated in the entire spectral range. Scatter loss as a function of surface roughness was calculated at 1064 nm, 1572 nm, and 4.1 μm, representing a primary wavelength, a secondary wavelength, and a middle wave infrared band selected for a dual-wavelength laser beam expander, respectively. The surface requirement of the aluminum alloy substrates was determined. Calculated and measured spectral reflectances were compared. Laser-induced damage threshold tests were performed at 1064 nm, 20 ns, and 20 Hz. A laser-induced damage threshold of 47 J/cm{sup 2} was determined. Post-damage analysis suggests that nodule defects are the limiting factor for the laser-induced damage threshold. Surface modification of the aluminum alloy was identified as a potential technical solution that may further increase the laser damage resistance of the dielectric enhanced dual-wavelength reflective optics. - Highlights: • A dual-wavelength was considered on dielectric enhanced mirrors. • A modified plasma-ion assisted deposition enabled in-situ plasma smoothing. • Optical constants were derived from deep ultraviolet to long-wave infrared. • Laser-induced damage mechanism was discussed.

  11. Dual-wavelength imaging of tumor progression by activatable and targeting near-infrared fluorescent probes in a bioluminescent breast cancer model.

    Directory of Open Access Journals (Sweden)

    Bang-Wen Xie

    Full Text Available Bioluminescence imaging (BLI has shown its appeal as a sensitive technique for in vivo whole body optical imaging. However, the development of injectable tumor-specific near-infrared fluorescent (NIRF probes makes fluorescence imaging (FLI a promising alternative to BLI in situations where BLI cannot be used or is unwanted (e.g., spontaneous transgenic tumor models, or syngeneic mice to study immune effects.In this study, we addressed the questions whether it is possible to detect tumor progression using FLI with appropriate sensitivity and how FLI correlates with BLI measurements. In addition, we explored the possibility to simultaneously detect multiple tumor characteristics by dual-wavelength FLI (~700 and ~800 nm in combination with spectral unmixing. Using a luciferase-expressing 4T1-luc2 mouse breast cancer model and combinations of activatable and targeting NIRF probes, we showed that the activatable NIRF probes (ProSense680 and MMPSense680 and the targeting NIRF probes (IRDye 800CW 2-DG and IRDye 800CW EGF were either activated by or bound to 4T1-luc2 cells. In vivo, we implanted 4T1-luc2 cells orthotopically in nude mice and were able to follow tumor progression longitudinally both by BLI and dual-wavelength FLI. We were able to reveal different probe signals within the tumor, which co-localized with immuno-staining. Moreover, we observed a linear correlation between the internal BLI signals and the FLI signals obtained from the NIRF probes. Finally, we could detect pulmonary metastases both by BLI and FLI and confirmed their presence histologically.Taken together, these data suggest that dual-wavelength FLI is a feasible approach to simultaneously detect different features of one tumor and to follow tumor progression with appropriate specificity and sensitivity. This study may open up new perspectives for the detection of tumors and metastases in various experimental models and could also have clinical applications, such as image

  12. Modulating dual-wavelength multiple quantum wells in white light emitting diodes to suppress efficiency droop and improve color rendering index

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yukun; Wang, Shuai; Zheng, Min; Ding, Wen [Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Yun, Feng, E-mail: fyun2010@mail.xjtu.edu.cn [Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Su, Xilin; Yang, Xiangrong; Liu, Shuo [Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Guo, Maofeng [Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Zhang, Ye [Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)

    2015-10-14

    In this paper, gallium nitride (GaN) based white light-emitting diodes (WLEDs) with modulated quantities of blue (In{sub 0.15}Ga{sub 0.85}N) quantum wells (QWs) and cyan QWs (In{sub 0.18}Ga{sub 0.82}N) in multiple QW (MQW) structures have been investigated numerically and experimentally. It is demonstrated that the optical performance of LEDs is sensitive to the quantities of cyan QWs in dual-wavelength MQW structures. Compared to the LEDs with respective 0, 4, and 8 cyan QWs (12 QWs in total), the optical performance of the sample with 6 cyan QWs is the best. The deterioration of the optical performance in the sample with less (4 pairs) cyan QWs or more (8 pairs) cyan QWs than 6 cyan QWs may be ascribed to weakened reservoir effect or more defects induced. Compared to conventional blue LEDs (12 blue QWs), the sample with 6 cyan QWs could effectively suppress the efficiency droop (the experimental droop ratio decreases from 50.3% to 39.5% at 80 A/cm{sup 2}) and significantly improve the color rendering index (CRI, increases from 66.4 to 77.0) simultaneously. We attribute the droop suppression to the strengthened reservoir effect and carrier confinement of deeper QWs (higher indium composition) incorporated in the dual-wavelength MQW structures, which lead to the better hole spreading and enhanced radiative recombination. Meanwhile, the remarkable experimental CRI improvement may result from the wider full-width at half-maximum of electroluminescence spectra and higher cyan intensity in WLED chips with dual-wavelength MQW structures.

  13. A compact dual-wavelength Nd:LuVO4 laser with adjustable power-ratio between 1064 nm and 1342 nm lines by controlling polarization dependent loss

    Science.gov (United States)

    Qi, Yaoyao; Yu, Haijuan; Zhang, Jingyuan; Zhang, Ling; He, Chaojian; Lin, Xuechun

    2017-01-01

    We demonstrate a compact dual-wavelength operation of Nd:LuVO4 laser with a power-ratio adjustable between 1064 nm and 1342 nm lines in a compound cavity configuration. The output power at two wavelengths of the laser indicates that it depends not only on pumping-power and but also on the controllable polarization loss in the cavity. Also, the power-ratio, defined as ratio between the output power at 1064 nm and that at 1342 nm, can be adjusted from 0 to 8 or higher accurately by rotating a quarter-wave plate (QWP) in the cavity.

  14. 双波长数字全息相位解包裹方法研究%Investigation on Phase Unwrapping in Dual-Wavelength Digital Holography

    Institute of Scientific and Technical Information of China (English)

    王羽佳; 江竹青; 高志瑞; 蔡文苑; 伍江涛

    2012-01-01

    使用两个不同的波长分别记录数字全息图,分别由数值再现得到每个波长对应的包裹相位图,再求得两者的相位差得到等效波长的相位图,通过此双波长相位解包裹方法得到连续的相位分布以消除相位包裹.通过数值模拟研究了双波长相位解包裹方法,搭建了双波长数字全息实验系统,并利用660 nm和671 nm两个波长的激光对标准石英平片和平凹透镜进行了相衬成像.通过双波长相位解包裹方法得到了连续的相位分布,实验结果与数值模拟结果具有较好的一致性,证明了双波长相位解包裹方法的有效性.%Two individual digital holograms are recorded by using two different wavelengths,respectively,and two phase images for the wavelengths are obtained after numerical reconstruction. Subtraction of the two phase images corresponding to two wavelengths can yield a new phase image for the beat wavelength. The final phase image is free of 2π discontinuities after dual-wavelength phase unwrapping. This method is explored by numerical simulation,and then a dual-wavelength digital holographic experimental setup is constructed. In the experiment,two lasers of different wavelengths of 660 nm and 671 nm are used to make phase contrast imaging to a standard quartz flake and a plano-concave lens. Continuous phase images are obtained by dual-wavelength phase unwrapping method. The experimental results are in good agreement with the numerical simulation. The effectiveness of dual-wavelength phase unwrapping is demonstrated.

  15. Lidar observations of tropical high-altitude cirrus clouds: results from dual-wavelength Raman lidar measurements during the ALBATROSS campaign 1996

    Science.gov (United States)

    Beyerle, Georg; Schaefer, H. J.; Schrems, Otto; Neuber, R.; Rairoux, P.; McDermid, I. S.

    1997-05-01

    Results from dual wavelength Raman lidar observations of tropical high-altitude cirrus clouds are reported. Based on 107 hours of night-time measurements cirrus clouds were present in more than 50% of the observations at latitudes between 23.5 degrees south and 23.5 degrees north and altitudes between 11 and 16 km. Volume depolarization is found to be a sensitive parameter for the detection of subvisible cloud layers. Using Mie scattering calculations estimates of the ice water content are derived.

  16. Efficient dual-wavelength excitation of Tb3+ emission in rare-earth doped KYF4 cubic nanocrystals dispersed in silica sol-gel matrix

    Science.gov (United States)

    del-Castillo, J.; Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.

    2014-11-01

    Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol-gel derived transparent nano-glass-ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+-Tb3+-Yb3+ doped nano-glass-ceramics can be activated in a dual-wavelength mode yielding efficient blue-green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes.

  17. Dual-wavelength in-line phase-shifting interferometry based on two dc-term-suppressed intensities with a special phase shift for quantitative phase extraction.

    Science.gov (United States)

    Xu, Xiaoqing; Wang, Yawei; Xu, Yuanyuan; Jin, Weifeng

    2016-06-01

    To efficiently promote the phase retrieval in quantitative phase imaging, a new approach of quantitative phase extraction is proposed based on two intensities with dual wavelength after filtering the corresponding dc terms for each wavelength, in which a special phase shift is used. In this approach, only the combination of the phase-shifting technique and subtraction procedures is needed, and no additional algorithms are required. The thickness of the phase object can be achieved from the phase image, which is related to the synthetic beat wavelength. The feasibility of this method is verified by the simulated experiments of the optically transparent objects.

  18. Cloud radar deployment for Indian Monsoon observations: Preliminary Results

    Science.gov (United States)

    Chakravarty, K.; Kalapureddy, M.; Pa, M.; Deshpandy, S.; Das, S.; Pandithurai, G.; Prabhakaran, T.; Chandrasekar, C. V.; Goswami, B.

    2013-12-01

    Indian Institute of Tropical Meteorology (IITM)'s acquired Ka-band radar for the Study of the interaction between Cloud and Environment for formation of Precipitation. Main objective of it is to make simultaneous high resolution measurements on dynamical, cloud microphysical and precipitation parameters pertain to monsoon system probably at diverse locations. The goal is to understand the interplay between cloud processes and environment that not only allow understanding the fundamental cloud-environment interactions but also precipitation formation mechanisms and further to estimate cloud contribution to the re-distribution of energy and water in climate system. For this, Polarimetric weather Doppler Radar at higher frequencies (9.5 and 35 GHz) can be a potential tool to gain knowledge on this scientific as well as societal application oriented programme. IITM's Polarimetric scanning Ka-band (cloud) radar operations started recently during May 2013. Mobile Ka-band Scanning Polarimetric Doppler Radar (KaSPR) is a cloud radar operating at wavelength of 8.5 mm with average powers of 110 W. KaSPR incorporates a conduction cooled Extended Interaction Klystron Amplifier. It is having four foot diameter Ka-band cassegrain antenna. Liquid cooled air-sealed RF unit provides excellent temperature stability. Antenna on the top of RF unit is mounted on the Elevation over azimuth pedestal which is designed to rotate continuously in the azimuth axis and a full 180 degrees in the elevation axis (horizon to horizon) with a maximum velocity of 200/sec and maximum acceleration of 120/s2. KaSPR uses dual channel 16-bit digital receiver having dynamic range of more than 80 dB with bandwidths 10 MHz. Arbitrary waveform generator capable of generating any user-defined waveform of up to 16K samples in length. It is having sensitivity of the order -45 dBZ at 5 km. KaSPR has been providing high sensitivity versatile measurements of cloud and precipitation at tropical site (Manderdev, 18

  19. Diagnosis of testicular torsion by measuring attenuation of dual wavelengths in transmission geometry across the testis: an experimental study in a rat model.

    Science.gov (United States)

    Canpolat, Murat; Yucel, Selcuk; Sircan-Kucuksayan, Aslinur; Kol, Arif; Kazanci, H Ozgur; Denkceken, Tuba

    2012-04-01

    To develop a noninvasive and real-time dual-wavelengths optic system to detect testicular torsion in an animal model. Diagnosis of testicular torsion is challenging in emergency conditions and frequently ends with surgical exploration. In this study, 9 male 8-month-old Wistar albino rats weighing an average of 400 g were used. A transverse incision on the upper scrotum was done and the right testis was torsed with a 720° medial rotation. The other testis of each rat was used as the control or sham group. In the sham group, the testicle was moved out of the body but no torsion was applied before repositioning into the scrotum. Transmission of continuous-wave light through all testes at wavelengths of 660 nm and 940 nm were measured. The ratio of the average intensities of the transmitted light of both wavelengths--660 nm to 940 nm--was used as a parameter to diagnose testis torsion. The ratios were significantly different (P = .001) between the torsion group and control group. Our noninvasive technique measuring attenuation of dual wavelengths in transmission geometry across the testis has the ability to distinguish between the testis with and without torsion on the basis of a threshold value of the ratio. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Dual-wavelength passive and hybrid mode-locking of 3, 4.5 and 10 GHz InAs/InP(100) quantum dot lasers.

    Science.gov (United States)

    Tahvili, M S; Du, L; Heck, M J R; Nötzel, R; Smit, M K; Bente, E A J M

    2012-03-26

    We present an investigation of passive and hybrid mode-locking in Fabry-Pérot type two-section InAs/InP(100) quantum dot lasers that show dual wavelength operation. Over the whole current and voltage range for mode-locking of these lasers, the optical output spectra show two distinct lobes. The two lobes provide a coherent bandwidth and are verified to lead to two synchronized optical pulses. The generated optical pulses are elongated in time due to a chirp which shows opposite signs over the two spectral lobes. Self-induced mode-locking in the single-section laser shows that the dual-wavelength spectra correspond to emission from ground state. In the hybrid mode-locking regime, a map of locking range is presented by measuring the values of timing jitter for several values of power and frequency of the external electrical modulating signal. An overview of the systematic behavior of InAs/InP(100) quantum dot mode-locked lasers is presented as conclusion.

  1. Remote beating of parallel or orthogonally polarized dual-wavelength optical carriers for 5G millimeter-wave radio-over-fiber link.

    Science.gov (United States)

    Wang, Huai-Yung; Chi, Yu-Chieh; Lin, Gong-Ru

    2016-08-08

    A novel millimeter-wave radio over fiber (MMW-RoF) link at carrier frequency of 35-GHz is proposed with the use of remotely beating MMW generation from reference master and injected slave colorless laser diode (LD) carriers at orthogonally polarized dual-wavelength injection-locking. The slave colorless LD supports lasing one of the dual-wavelength master modes with orthogonal polarizations, which facilitates the single-mode direct modulation of the quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) data. Such an injected single-carrier encoding and coupled dual-carrier transmission with orthogonal polarization effectively suppresses the cross-heterodyne mode-beating intensity noise, the nonlinear modulation (NLM) and four-wave mixing (FWM) sidemodes during injection locking and fiber transmission. In 25-km single-mode fiber (SMF) based wireline system, the dual-carrier under single-mode encoding provides baseband 24-Gbit/s 64-QAM OFDM transmission with an error vector magnitude (EVM) of 8.8%, a bit error rate (BER) of 3.7 × 10-3, a power penalty of wireless transmission, the beat MMW carrier at 35 GHz can deliver the passband 16-QAM OFDM at 4 Gbit/s to show corresponding EVM and BER of 15.5% and 1.4 × 10-3, respectively, after 25-km SMF and 1.6-m free-space transmission.

  2. Reduction in thigh circumference and improvement in the appearance of cellulite with dual-wavelength, low-level laser energy and massage.

    Science.gov (United States)

    Gold, Michael H; Khatri, Khalil A; Hails, Kelley; Weiss, Robert A; Fournier, Nathalie

    2011-02-01

    This study evaluated the efficacy and safety of a low-level, dual-wavelength laser energy and massage device for improving the appearance of cellulite and reducing thigh circumference. Subjects (n = 83) with mild to moderate cellulite enrolled in this IRB-approved, open-label, multicenter study. Their right or left thighs received eight treatments with a low-level, dual-wavelength laser and massage device. The untreated contralateral thigh served as a control. Circumferences of the upper, middle, and lower thighs (treated and untreated) were measured before the fifth and eighth treatments and 1 month after the final treatment. Reduction in thigh circumference of the treated areas exceeded those of the control areas for the upper, middle, and lower thigh in most subjects. The maximum reduction (-0.82 cm) occurred in the upper thigh at 1 month. The mean reduction of the upper, middle, and lower thigh circumferences was -0.64 cm for the treated thighs compared to -0.20 cm for untreated thighs. The difference was significant (p cellulite while reducing thigh circumference.

  3. Tunable and switchable dual-wavelength single polarization narrow linewidth SLM erbium-doped fiber laser based on a PM-CMFBG filter.

    Science.gov (United States)

    Yin, Bin; Feng, Suchun; Liu, Zhibo; Bai, Yunlong; Jian, Shuisheng

    2014-09-22

    A tunable and switchable dual-wavelength single polarization narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser based on polarization-maintaining chirped moiré fiber Bragg grating (PM-CMFBG) filter is proposed and demonstrated. For the first time as we know, the CMFBG inscribed on the PM fiber is applied for the wavelength-tunable and-switchable dual-wavelength laser. The PM-CMFBG filter with ultra-narrow transmission band (0.1 pm) and a uniform polarization-maintaining fiber Bragg grating (PM-FBG) are used to select the laser longitudinal mode. The stable single polarization SLM operation is guaranteed by the PM-CMFBG filter and polarization controller. A tuning range of about 0.25 nm with about 0.075 nm step is achieved by stretching the uniform PM-FBG. Meanwhile, the linewidth of the fiber laser for each wavelength is approximate 6.5 and 7.1 kHz with a 20 dB linewidth, which indicates the laser linewidth is approximate 325 Hz and 355 Hz FWHM.

  4. A switchable and stable single-longitudinal-mode, dual-wavelength erbium-doped fiber laser assisted by Rayleigh backscattering in tapered fiber

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Jian; Yang, Yanfu, E-mail: yangyanfu@hotmail.com; Zhang, Jianyu; Wang, Xiaorui; Yuan, Yijun; Yao, Yong [College of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, Guangdong Province 518055 (China); Liu, Meng [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798 Singapore (Singapore)

    2015-09-14

    We have proposed and demonstrated a novel switchable single-longitudinal-mode (SLM), dual-wavelength erbium-doped fiber laser (DWEDFL) assisted by Rayleigh backscattering (RBS) in a tapered fiber in a ring laser configuration. The RBS feedback in a tapered fiber is a key mechanism as linewidth narrowing for laser output. A compound laser cavity ensured that the EDFL operated in the SLM state and a saturable absorber (SA) is employed to form a gain grating for both filtering and improving wavelength stability. The fiber laser can output dual wavelengths simultaneously or operate at single wavelength in a switchable manner. Experiment results show that with the proper SA, the peak power drift was improved from 1–2 dB to 0.31 dB and the optical signal to noise ratio was higher than 60 dB. Under the assistance of RBS feedback, the laser linewidths are compressed by around three times and the Lorentzian 3 dB linewidths of 445 Hz and 425 Hz are obtained at 1550 nm and 1554 nm, respectively.

  5. Dual-wavelength excitation to reduce background fluorescence for fluorescence spectroscopic quantitation of erythrocyte zinc protoporphyrin-IX and protoporphyrin-IX from whole blood and oral mucosa

    Science.gov (United States)

    Hennig, Georg; Vogeser, Michael; Holdt, Lesca M.; Homann, Christian; Großmann, Michael; Stepp, Herbert; Gruber, Christian; Erdogan, Ilknur; Hasmüller, Stephan; Hasbargen, Uwe; Brittenham, Gary M.

    2014-02-01

    Erythrocyte zinc protoporphyrin-IX (ZnPP) and protoporphyrin-IX (PPIX) accumulate in a variety of disorders that restrict or disrupt the biosynthesis of heme, including iron deficiency and various porphyrias. We describe a reagent-free spectroscopic method based on dual-wavelength excitation that can measure simultaneously both ZnPP and PPIX fluorescence from unwashed whole blood while virtually eliminating background fluorescence. We further aim to quantify ZnPP and PPIX non-invasively from the intact oral mucosa using dual-wavelength excitation to reduce the strong tissue background fluorescence while retaining the faint porphyrin fluorescence signal originating from erythrocytes. Fluorescence spectroscopic measurements were made on 35 diluted EDTA blood samples using a custom front-face fluorometer. The difference spectrum between fluorescence at 425 nm and 407 nm excitation effectively eliminated background autofluorescence while retaining the characteristic porphyrin peaks. These peaks were evaluated quantitatively and the results compared to a reference HPLC-kit method. A modified instrument using a single 1000 μm fiber for light delivery and detection was used to record fluorescence spectra from oral mucosa. For blood measurements, the ZnPP and PPIX fluorescence intensities from the difference spectra correlated well with the reference method (ZnPP: Spearman's rho rs = 0.943, p erythrocyte ZnPP and PPIX.

  6. Thermal and laser properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ for high power dual-wavelength laser.

    Science.gov (United States)

    Wu, K; Hao, L Z; Yu, H H; Wang, Z P; Wang, J Y; Zhang, H J

    2012-03-26

    We measured the thermal properties of Nd:Lu₃Sc₁.₅Ga₃.₅O₁₂ (Nd:LuSGG) crystal, including the thermal expansion coefficient, specific heat, and thermal diffusion coefficient. The calculated thermal conductivity is 4.4 W/mK at room temperature. A high-power continuous-wave and passively Q-switched Nd:LuSGG laser was also demonstrated. Continuous-wave output power of 6.96 W is obtained which is the highest power with this material. For the first time to our knowledge, the passively Q-switched Nd:LuSGG laser is reported with the shortest pulse width, largest pulse energy, and highest peak power are achieved to be 5.1 ns, 62.5 μJ, and 12 kW, respectively. By spectral analysis, it has been found that the Nd:LuSGG laser was located at 1059 nm under low pump power, and became dual-wavelength at 1061.5 and 1059 nm when the incident pump power is over 2.27 W. The generating mechanism of dual-wavelength laser is also discussed.

  7. Phase correlator reduces mm-wave radar cost

    Science.gov (United States)

    Weiss, R., Sr.; Hobbs, P.; Locatelli, J.

    1986-03-01

    A technique involving the IC storage of magnetron phase for reference has been developed to make possible the use of the low-cost efficient magnetron in obtaining phase coherent signals for pulse Doppler radar. In the new external coherence method, the recorded random midpulse-region phase is compared with the frequency of the echo allowing Doppler information, free of phase noise, to be extracted. The gated magnetron was tested at Ka-band in a 35-GHz radar, and good agreement with the CP-4 5.5 GHz radar was shown. With good accuracy down to 10 cm/s, the present system, especially in the mm-wave region, has important applications to meteorological and military radar.

  8. A tunable and switchable single-longitudinal-mode dual-wavelength fiber laser incorporating a reconfigurable dual-pass Mach-Zehnder interferometer and its application in microwave generation

    Science.gov (United States)

    Wang, Fei; Xu, En-Ming; Dong, Jian-Ji; Zhang, Xin-Liang

    2011-05-01

    A tunable and switchable single-longitudinal-mode (SLM) dual-wavelength fiber laser incorporating a reconfigurable dual-pass Mach-Zehnder interferometer (MZI) filter was proposed and demonstrated, which can be applied in microwave generation. By incorporating a high extinction ratio (ER) dual-pass MZI into an erbium-doped fiber ring cavity, SLM dual-wavelength lasing can be achieved even using a MZI with relatively little free spectrum range (FSR), and by beating the two wavelengths at a photodetector, a 9.76 GHz microwave signal with a 3-dB bandwidth of less than 10 kHz is obtained. Moreover, by direct linking the two outputs of the MZI, the high ER dual-pass MZI is easily reconfigured as a half FSR dual-pass MZI. Using this structure, switchable SLM dual-wavelength lasing can be conveniently realized.

  9. The lidar dark band: An oddity of the radar bright band analogy

    Energy Technology Data Exchange (ETDEWEB)

    Sassen, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1996-04-01

    Although much has sbeen learned from independent radar and lidar studies of atmospheric precipitations, occasionally supported by aircraft profiling, what has been lacking is combined optical, microwave, and insitu observations of the melting layer. Fortunately, the rainshowers on April 21, 1994, during the Remote Cloud Sensing intensive obervations Period (RCSIOP) at the Southern Great Plains Cloud and radiation Testbed (CART) site provided an opportunity for coordinated dual-wavelength University of Utah Polarization Diversity Lidar, University of Massachusetts Cloud Profiling Radar System Doppler Radar, and the University of North Dakota Citation aircraft measurements.

  10. A Multi-Frequency Wide-Swath Spaceborne Cloud and Precipitation Imaging Radar

    Science.gov (United States)

    Li, Lihua; Racette, Paul; Heymsfield, Gary; McLinden, Matthew; Venkatesh, Vijay; Coon, Michael; Perrine, Martin; Park, Richard; Cooley, Michael; Stenger, Pete; hide

    2016-01-01

    Microwave and millimeter-wave radars have proven their effectiveness in cloud and precipitation observations. The NASA Earth Science Decadal Survey (DS) Aerosol, Cloud and Ecosystems (ACE) mission calls for a dual-frequency cloud radar (W band 94 GHz and Ka-band 35 GHz) for global measurements of cloud microphysical properties. Recently, there have been discussions of utilizing a tri-frequency (KuKaW-band) radar for a combined ACE and Global Precipitation Measurement (GPM) follow-on mission that has evolved into the Cloud and Precipitation Process Mission (CaPPM) concept. In this presentation we will give an overview of the technology development efforts at the NASA Goddard Space Flight Center (GSFC) and at Northrop Grumman Electronic Systems (NGES) through projects funded by the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP). Our primary objective of this research is to advance the key enabling technologies for a tri-frequency (KuKaW-band) shared-aperture spaceborne imaging radar to provide unprecedented, simultaneous multi-frequency measurements that will enhance understanding of the effects of clouds and precipitation and their interaction on Earth climate change. Research effort has been focused on concept design and trade studies of the tri-frequency radar; investigating architectures that provide tri-band shared-aperture capability; advancing the development of the Ka band active electronically scanned array (AESA) transmitreceive (TR) module, and development of the advanced radar backend electronics.

  11. Design and study on the dual-band radome with FSS operation at Ku-/Ka-band%Ku/Ka波段双通带频率选择表面雷达罩设计研究

    Institute of Scientific and Technical Information of China (English)

    王秀芝; 高劲松; 徐念喜

    2013-01-01

    In order to meet the multi-band and integration requirements of the communication apparatus, the coupling and resonance mecha-nism can be exploited to design a frequency selective surface (FSS), with two pass-bands at Ku-band and Ka-band, which is composed of three metallic layers and fabricated on a flat substrate equivalent to a solid wall radome or an A-sandwiched radome. According to the physical structure of the FSS, an equivalent circuit model is established to analyze the filtering mechanism, and the transmission characteristics of the radomes with FSS are obtained by using a full-wave analysis software. The first pass-band at Ku-band with miniaturization property can be achieved by coupling the electric and magnetic field of the three surfaces, while the second pass-band at Ka-band can be achieved by the resonance of the square loop slots embedded in the capacitive surfaces. The transmissions of the solid wall radome and A-sandwiched radome with FSS are 89%and 94.7%at Ku-band, and 88.2%and 93.7%at Ka-band, respectively. When the incident angle is varied from normal to 60◦, the frequency response characteristics of the two pass-bands are stable. Finally, the experimental results of the prototype with a solid substrate measured in free-space environment are in good agreement with the simulated values. The proposed radome structure with FSS, which is based on the coupling and resonance mechanism, can achieve two stable pass-bands at Ku-/Ka-band. This may provide some theoretical and experimental assistance for the study of the multi-band and wide band spacing FSS.%为了满足现代通信设备多频带及集成化要求,基于耦合机理和谐振机理,在实心半波壁雷达罩和A夹层雷达罩等效平板基底上设计了一种由容性表面(内嵌谐振单元)-感性表面-容性表面(内嵌谐振单元)-等效基底级联而成的Ku/Ka波段双通带频率选择表面结构.根据FSS的物理结构建立了等效电路模型,分析了滤波机

  12. Non-invasive image-guided laser microsurgery by a dual-wavelength fiber laser and an integrated fiber-optic multi-modal system.

    Science.gov (United States)

    Tsai, Meng-Tsan; Li, Dean-Ru; Chan, Ming-Che

    2016-10-15

    A new approach to non-invasive image-guided laser micro-treatment is demonstrated by a dual-wavelength fiber laser source and an integrated fiber-based multi-modal system. The fiber-based source, operated in 1.55 and 1.2 μm simultaneously, was directly connected to an integrated fiber-based multi-modal system for imaging and laser micro-treatment at the same time. The 1.2 μm radiations, within the 1.2-1.35 μm bio-penetration window of skin, were utilized for spectral domain optical coherence tomography imaging. The 1.55 μm radiations, highly absorptive to waters, were utilized for laser microsurgery. The new approach, which is simple in configuration and accurately controls the positions and exposure time of the laser microsurgery, shows great promises for future clinical applications.

  13. Q-switched dual-wavelength fiber laser using a graphene oxide saturable absorber and singlemode-multimode-singlemode fiber structure

    Science.gov (United States)

    Ahmad, H.; Zulkifli, A. Z.; Yasin, M.; Thambiratnam, K.

    2016-10-01

    A Q-switched dual-wavelength fiber laser using a graphene oxide-based saturable absorber to generate the desired output pulses is proposed and demonstrated. The system utilizes a singlemode-multimode-singlemode fiber structure to control the net losses in the cavity so that only two dominant wavelengths are allowed to oscillate. The proposed system is capable of generating an output with a high repetition rate of 27.1 kHz and a narrow pulse width of 4.03 µs. The output pulses also have average output power and pulse energy of up to 0.5 mW and 18.5 nJ, respectively. The 1st harmonic obtained has a high signal-to-noise ratio of 33.2 dB, indicating a highly stable pulse output with minimum mode hopping.

  14. Diode-pumped dual-wavelength Nd:LSO laser at 1059 and 1067  nm with nearly diffraction-limited beam quality.

    Science.gov (United States)

    Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Wang, Yi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Jian; Xu, Jun

    2016-04-10

    We report a diode-pumped continuous-wave simultaneous dual-wavelength Nd:LSO laser at 1059 and 1067 nm. By employing a specially coated output coupler with relatively high transmissions at high-gain emission lines of 1075 and 1079 nm, the two low-gain emission lines, 1059 and 1067 nm, can be achieved, for the first time to our knowledge, with maximum output power of 1.27 W and slope efficiency of about 29.2%. The output power is only limited by the available pump power. Output beam quality is also measured to be about 1.19 and 1.21 of the beam propagation factors in the x and y directions, respectively.

  15. Efficient stable simultaneous CW dual-wavelength diode-end-pumped Nd :YAG laser operating at 1.319 and 1.338 μm

    Institute of Scientific and Technical Information of China (English)

    Rui Zhou; Wuqi Wen; Zhiqiang Cai; Xin Ding; Peng Wang; Jianquan Yao

    2005-01-01

    An efficient, stable diode-end-pumped simultaneous continuous-wave (CW) dual-wavelength laser operating at 1.319 and 1.338 μm in a Nd:YAG crystal has been demonstrated. A total output power of 6.3 W is achieved at an absorbed pump power of 15 W, with a slope efficiency of 43.5%. The instability of output power is less than 1%. With a type Ⅱ critical phase-matched KTP crystal inserted into the cavity as frequency doubler, a maximum output power of 200 mW in red region is acquired. In addition, a sixwavelength laser operation at 1.319 μm, 1.338 μm, 1.356 μm, 659.5 nm, 669 nm, and 678 nm is observed.

  16. OCDMA PON supporting ONU inter-networking based on gain-switched Fabry-Pérot lasers with external dual-wavelength injection.

    Science.gov (United States)

    Liu, Jie; Zeng, Duoduo; Guo, Changjian; Xu, Lei; He, Sailing

    2010-10-25

    We propose and demonstrate an OCDMA-PON scheme with optical network unit (ONU) internetworking capability, which utilizes low-cost gain-switched Fabry-Pérot (GS-FP) lasers with external dual-wavelength injection as the pulse sources on the ONU side. The injection-generated optical pulses in two wavelengths from the same GS-FP laser are used separately for the PON uplink transmission and ONU internetworking. Experimental results based on a two-user OCDMA system confirm the feasibility of the proposed scheme. With OCDMA technologies, separate ONU-internetworking groups can be established using different optical codes. We also give experiment results to analyze the performance of the ONU-ONU transmission at different power of interference signals when two ONU-internetworking groups are present in the OCDMA-PON.

  17. Ka-BAND MICROSTRIP INTEGRATED LOCAL-OSCILLATOR-MIXER ASSEMBLY USED IN PROJECTILE SENSORS%用于抛掷敏感器的Ka-波段微带集成本振-混频组件

    Institute of Scientific and Technical Information of China (English)

    蒋金水; 李兴国; 吴文; 娄国伟

    2001-01-01

    A compact Ka-band microstrip integrated local-oscillator-mixer assembly used in projectile sensors was introduced. The overall configuration of microstrip circuit of this assembly was given. The functions of each component were described. The environment and reliability tests performed on this assembly were explored in detail, which include vibration, shock and temperature. The Ka-band local-oscillator-mixer assembly exhibits a 3.4~4.2-dB double side band (DSB) noise figure over a 2-GHz RF bandwidth. LO-to-RF isolation is greater than 27dB over the range of operating frequencies. The frequency stability of local oscillator with dielectric resonator used is less than 60ppm/℃.%介绍一种用于抛掷敏感器的结构紧凑的Ka-波段微带集成本振-混频组件,给出了该组件的微带电路结构,叙述了其中每一部件的功能.对该组件仔细做了环境和可靠性实验,其中包括震动,冲击和温度.在2GHz射频带宽内,该组件的双边带噪声系数是3.4~4.2dB,在其工作频带内本振到射频的隔离度大于27dB.由于使用了介质谐振器,本振的频率稳定度小于60ppm/℃.

  18. Calculation of attenuation by rain using the DAH model and diameter of antennas for the Ka Band in Mexico; Calculo de atenuacion por lluvia usando el modelo DAH y diametro de antena para Banda Ka en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Landeros-Ayala, S.; Neri-Vela, R; Cruz-Sanchez, H.; Hernandez-Bautista, H. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2002-03-01

    In the last years, the peak in the demand of satellite communication service has caused the saturation in the use of the frequencies corresponding to the band, Cand Ku. Due to this, the engineers have looked for viable alternatives, in order to satisfy the current requisition, as well as the future demand, for which a considerable increment is expected. One of these alternatives is the use of the Ka Band (20Hz/30Hz), that is why the importance of studying the propagation effects that are experienced at these frequencies, especially the attenuation effect by rain, as in this case, where it is significant. The present article has the purpose to describe the use of the Modelo DAH (whose authors are Asoka Dissanayake, Jeremy Allnutt and Fatim Haidara), mixed with the global maps of distribution of rain by Crane, for the calculation of the attenuation by rain in satellite communication systems operated in the Ka Band. Besides, antenna diameters for the systems of communications in Ka Band in different locations of the Mexican Republic, using for it the attenuation margins for rain obtained through the Modelo DAH, and using as references the characteristics of the ANIK F2 satellite and a terrestrial station VSAT, are proposed. [Spanish] En los ultimos anos, el auge en la demanda de servicios de comunicacion por satelite ha provocado la saturacion en los uso de la frecuencia correspondientes a las bandas C y Ku. Debido a esta razon, se han buscado alternativas viables para poder satisfacer la demanda actual, asi como la demanda futura, para la cual se espera un incremento considerable. Una de estas alternativas es el uso de Banda Ka (20Hz/30Hz), de ahi la importancia del estudio sobre los efectos de programacion que se experimentan a esta frecuencia, en especial, el efecto de atencion por lluvias, ya que sen este caso resulta ser significativa. El presente articulo tiene como finalidad describir el uso del Modelo DAH (cuyos autores son Asoka Dissanayake, Jeremy Allnutt y

  19. Single- and dual-wavelength photodetectors with MgZnO/ZnO metal-semiconductor-metal structure by varying the bias voltage

    Science.gov (United States)

    Hwang, J. D.; Lin, G. S.

    2016-09-01

    By varying the bias voltage of an Mg x Zn1-x O/ZnO metal-semiconductor-metal photodetector (MSM-PDs), the detection wavelength can be modulated from a single to a dual wavelength. A long-wavelength band response is caused by the ZnO absorption and a short-wavelength band response is caused by Mg x Zn1-x O. At a 0 V bias voltage, the photogenerated electrons in ZnO are confined to the Mg x Zn1-x O/ZnO interface, arising from the piezoelectric polarization. The accumulated electrons hop the Mg x Zn1-x O layer through the assistance of defects; however, the photogenerated electrons in Mg x Zn1-x O cannot cross over the large barrier height at the Au/MgZnO interface, resulting in a single-wavelength photodetector with a long-wavelength band (345-400 nm) having a peak wavelength of 370 nm. By increasing the bias voltage to 1-2 V, the barrier height is lowered, enabling the photogenerated electrons in Mg x Zn1-x O to easily cross over the low barrier height, leading to dual-wavelength photodetectors having peak wavelengths of 370 and 340 nm. On further increasing the bias voltage beyond 2 V, the photogenerated electrons in ZnO sink deeply in the hollow at the Mg x Zn1-x O/ZnO interface owing to the large applied voltage. These electrons are effectively confined at the Mg x Zn1-x O/ZnO interface, which retards the tunneling of the photogenerated electrons in ZnO through the Mg x Zn1-x O layer; hence the MSM-PDs revert back to single wavelength photodetectors; however, the detection wavelength is different from that of the MSM-PDs biased at 0 V. Instead of having a long-wavelength band (345-400 nm), the MSM-PDs demonstrate a short-wavelength band (320-345 nm) at a 3 V bias voltage.

  20. 5,000 h reliable operation of 785nm dual-wavelength DBR-RW diode lasers suitable for Raman spectroscopy and SERDS

    Science.gov (United States)

    Sumpf, Bernd; Müller, André; Maiwald, Martin

    2016-03-01

    Monolithic wavelength stabilized diode lasers, e.g. distributed Bragg reflector (DBR) ridge waveguide (RW) lasers, are well-suited light sources for compact and portable Raman spectroscopic systems. In the case of in situ and outdoor investigations, the weak Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Among others, shifted excitation Raman difference spectroscopy (SERDS) has been demonstrated as a powerful and easy-to-use technique to separate the Raman lines from disturbing background signals. SERDS is based on subsequential excitation of the sample with two slightly shifted wavelengths. The Raman lines follow the change in the excitation wavelength whereas the non-Raman signals remain unchanged. For SERDS dual-wavelength light sources, e.g., mini-arrays containing two DBR-RW lasers, are requested. Moreover, for portable Raman instruments such as handheld devices robust and reliable excitation light sources with lifetimes > 1,000 h are preferred. In this work, reliability investigations of dual-wavelength DBR-RW mini-arrays over a total test time of 5,000 h are presented. Wavelength stabilization and narrowing of the spectral emission is realized by 10th-order DBR surface gratings defined by i-line wafer stepper technology. The DBR-section has a length of 500 μm, the devices a total length of 3 mm. The ridge waveguide has a stripe width of 2.2 μm. Maximum output powers up to 215 mW per emitter were measured. Over the whole power range, 95 % of the emitted power is within a spectral width of 0.15 nm (2.5 cm-1), which is smaller than the spectral width needed to resolve most Raman lines of solid and liquid samples. In a step-stress test, the devices were tested at 50 mW, followed by 75 mW and finally at 100 mW per emitter. Electro-optical and spectral measurements were performed before, during and after the test. All emitters under study did not show any deterioration of their

  1. Monitoring hypoxia induced changes in cochlear blood flow and hemoglobin concentration using a combined dual-wavelength laser speckle contrast imaging and Doppler optical microangiography system.

    Directory of Open Access Journals (Sweden)

    Roberto Reif

    Full Text Available A synchronized dual-wavelength laser speckle contrast imaging (DWLSCI system and a Doppler optical microangiography (DOMAG system was developed to determine several ischemic parameters in the cochlea due to a systemic hypoxic challenge. DWLSCI can obtain two-dimensional data, and was used to determine the relative changes in cochlear blood flow, and change in the concentrations of oxyhemoglobin (HbO, deoxyhemoglobin (Hb and total hemoglobin (HbT in mice. DOMAG can obtain three-dimensional data, and was used to determine the changes in cochlear blood flow with single vessel resolution. It was demonstrated that during a hypoxic challenge there was an increase in the concentrations of Hb, a decrease in the concentrations of HbO and cochlear blood flow, and a slight decrease in the concentration of HbT. Also, the rate of change in the concentrations of Hb and HbO was quantified during and after the hypoxic challenge. The ability to simultaneously measure these ischemic parameters with high spatio-temporal resolution will allow the detailed quantitative analysis of several hearing disorders, and will be useful for diagnosing and developing treatments.

  2. Continuous-wave simultaneous dual-wavelength and power-ratio-tunable operation at 1064 and 1342 nm in an Nd:LuVO4 laser

    Science.gov (United States)

    Hsu, C.-C.; Wu, S.-S.; Chou, C.-C.; Wei, M.-D.

    2011-11-01

    This study demonstrates continuous-wave simultaneous dual-wavelength emission at 1064 and 1342 nm in an Nd:LuVO4 laser by using a T-type cavity configuration. The output powers indicating a function of pump power had two evolutions depending on the strength of the completion of two wavelength emissions. One is that the output power increased linearly with the pump power in weak competition, and the output power and slope efficiency of 1064 and 1342 nm were 1.17 W and 13%, and 0.213 W and 2.8%, respectively. The other is that the extracting-energy capabilities of two wavelength emissions were close, and the evolution was not linear and the variations demonstrated multiple stages depending on the pump power. Moreover, the ratio of output power, defined as the output power at 1064 nm divided by that at 1342 nm, is tuned from 0 to 5.5 by varying the 1064 nm cavity, and equal output powers of 1064 and 1342 nm can be obtained at each pump power.

  3. Quantitative and qualitative determination of LiuweiDihuang preparations by ultra high performance liquid chromatography in dual-wavelength fingerprinting mode and random forest.

    Science.gov (United States)

    Qiu, Yixing; Huang, Jianhua; Jiang, Xingming; Chen, Yang; Liu, Yang; Zeng, Rong; Shehla, Nuzhat; Liu, Qiang; Liao, Duanfang; Guo, Dean; Liang, Yizeng; Wang, Wei

    2015-11-01

    The classical traditional Chinese formulation LiuweiDihuang, shown to have clinical efficacy for "nourishing kidney-yin" in traditional Chinese medicine, has been used for thousands of years in China. Little attention, however, has been paid to quality control methods for this formulation. Hence, a rapid and sensitive analytical technique is urgently needed for the evaluation of LiuweiDihuang preparations to assess its quality and pharmacological functionality. In this study, an ultra high performance liquid chromatography dual-wavelength method was developed to simultaneously determine 11 constituents in LiuweiDihuang preparations. This robust approach provided a fast and comprehensive quantitative determination of the major bioactive markers within LiuweiDihuang preparations. To distinguish four dosage forms of LiuweiDihuang preparations, a random forest technique was applied on the spectrometric fingerprint data obtained. This combination approach of chromatographic techniques and data analyses might serve as a rapid and efficient tool to ensure the quality of LiuweiDihuang preparations and other Chinese medicinal formulations and can support quality control and scientific research into the pharmacological potential for these formulations.

  4. Highly efficient dual-wavelength mid-infrared CW Laser in diode end-pumped Er:SrF2 single crystals

    Science.gov (United States)

    Ma, Weiwei; Qian, Xiaobo; Wang, Jingya; Liu, Jingjing; Fan, Xiuwei; Liu, Jie; Su, Liangbi; Xu, Jun

    2016-11-01

    The spectral properties and laser performance of Er:SrF2 single crystals were investigated and compared with Er:CaF2. Er:SrF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections and much longer fluorescence lifetimes of the upper laser level (Er3+:4I11/2 level) than those of Er:CaF2 crystals. Dual-wavelength continuous-wave (CW) lasers around 2.8 μm were demonstrated in both 4at.% and 10at.% Er:SrF2 single crystals under 972 nm laser diode (LD) end pumping. The laser wavelengths are 2789.3 nm and 2791.8 nm in the former, and 2786.4 nm and 2790.7 nm in the latter, respectively. The best laser performance has been demonstrated in lightly doped 4at.% Er:SrF2 with a low threshold of 0.100 W, a high slope efficiency of 22.0%, an maximum output power of 0.483 W.

  5. Ka频段陶瓷基板微带带通滤波器设计分析%Design of Ka-band Microstrip Bandpass Filter on Ceramic Substrate

    Institute of Scientific and Technical Information of China (English)

    赵飞; 党元兰; 王璇

    2012-01-01

    为满足微波电路小型化的发展要求,基于陶瓷基板设计了一款Ka频段的微带带通滤波器。分析了滤波器的电路设计原理及工艺设计方案,采用电路优化和三维全波仿真结合的方法对电路进行仿真。在优化后的版图基础上,通过改善膜层附着力、提高加工精度等方式对滤波器的加工进行控制。测试结果满足使用要求,证明了电路及工艺设计方案的正确性。%A Ka-band microstrip bandpass filter using ceramic substrate is designed to meet the requirement of microwave IC miniaturization.The circuit design principle and technology design scheme are analyzed.The circuit is simulated by combining the circuit optimization and 3D full-wave simulation.Based on the optimized layout,the processing of filter is controlled by improving the adhesion of the film and increasing the processing accuracy.The test result proves the validity of the microstrip bandpass filter and its design method.

  6. Similarities and differences between three coexisting spaceborne radars in global rainfall and snowfall estimation

    Science.gov (United States)

    Tang, Guoqiang; Wen, Yixin; Gao, Jinyu; Long, Di; Ma, Yingzhao; Wan, Wei; Hong, Yang

    2017-05-01

    Precipitation is one of the most important components in the water and energy cycles. Radars are considered the best available technology for observing the spatial distribution of precipitation either from the ground since the 1980s or from space since 1998. This study, for the first time ever, compares and evaluates the only three existing spaceborne precipitation radars, i.e., the Ku-band precipitation radar (PR), the W-band Cloud Profiling Radar (CPR), and the Ku/Ka-band Dual-frequency Precipitation Radar (DPR). The three radars are matched up globally and intercompared in the only period which they coexist: 2014-2015. In addition, for the first time ever, TRMM PR and GPM DPR are evaluated against hourly rain gauge data in Mainland China. Results show that DPR and PR agree with each other and correlate very well with gauges in Mainland China. However, both show limited performance in the Tibetan Plateau (TP) known as the Earth's third pole. DPR improves light precipitation detectability, when compared with PR, whereas CPR performs best for light precipitation and snowfall. DPR snowfall has the advantage of higher sampling rates than CPR; however, its accuracy needs to be improved further. The future development of spaceborne radars is also discussed in two complementary categories: (1) multifrequency radar instruments on a single platform and (2) constellations of many small cube radar satellites, for improving global precipitation estimation. This comprehensive intercomparison of PR, CPR, and DPR sheds light on spaceborne radar precipitation retrieval and future radar design.

  7. Ka-Band Phased Array System Characterization

    Science.gov (United States)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  8. The radio-on-fiber-wavelength-division-multiplexed-passive-optical network (WDM-RoF-PON) for wireless and wire layout with linearly-polarized dual-wavelength fiber laser and carrier reusing

    Science.gov (United States)

    Ji, Wei; Chang, Jun

    2013-07-01

    In this paper, we design a WDM-RoF-PON based on linearly-polarized dual-wavelength fiber laser and CSRZ-DPSK, which can achieve wire-line and wireless access synchronously. With the CSRZ-DPSK modulation, the wireless access in ONU can save RF source and the frequency of radio carrier can be controlled by OLT. The dual-wavelength fiber laser is the union light source of WDM-PON with polarization multiplexing. By the RSOA and downstream light source reusing, the ONU can save omit laser source and makes the WDM-PON to be colorless. The networking has the credible transmission property, including wireless access and fiber transmission. The networking also has excellent covering range.

  9. 785nm dual-wavelength Y-branch DBR-RW diode laser with electrically adjustable wavelength distance between 0 nm and 2 nm

    Science.gov (United States)

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2017-02-01

    Shifted excitation Raman difference spectroscopy is a powerful tool to separate the weak Raman lines from disturbing background light like fluorescence, day light or artificial light. When exciting the sample alternatingly with two slightly shifted wavelengths, the Raman lines follow the change whereas the background remains unchanged. Therefore, background free Raman spectra can be obtained measuring the two Raman spectra, subtracting the two signals and applying a reconstruction algorithm. When the spectral distance between the two wavelengths is the width of the Raman lines under study best signal-to-noise ratios can be achieved. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers with resistor heaters over the DBR gratings will be presented. The devices have a total length of 3 mm and a RW stripe width of 2.2 μm. The wavelengths are defined and stabilized using 500 μm long 10th order gratings with a designed spectral distance of 0.62 nm. Using the resistor heaters, this distance can be adjusted. The monolithic devices reach optical output powers up to 180 mW. Over the full range, they operate in single mode. The emission width is smaller than 13 pm (FWHM). At an output power of 50 mW the conversion efficiency is 0.22, which only slightly decreases down to 0.18 at maximal power. At an output power of 100 mW and with heater currents smaller than 600 mA, the spectral distance can be tuned from 0 nm up to 2 nm. The spectra remain single mode.

  10. A multi-view time-domain non-contact diffuse optical tomography scanner with dual wavelength detection for intrinsic and fluorescence small animal imaging.

    Science.gov (United States)

    Lapointe, Eric; Pichette, Julien; Bérubé-Lauzière, Yves

    2012-06-01

    We present a non-contact diffuse optical tomography (DOT) scanner with multi-view detection (over 360°) for localizing fluorescent markers in scattering and absorbing media, in particular small animals. It relies on time-domain detection after short pulse laser excitation. Ultrafast time-correlated single photon counting and photomultiplier tubes are used for time-domain measurements. For light collection, seven free-space optics non-contact dual wavelength detection channels comprising 14 detectors overall are placed around the subject, allowing the measurement of time point-spread functions at both excitation and fluorescence wavelengths. The scanner is endowed with a stereo camera pair for measuring the outer shape of the subject in 3D. Surface and DOT measurements are acquired simultaneously with the same laser beam. The hardware and software architecture of the scanner are discussed. Phantoms are used to validate the instrument. Results on the localization of fluorescent point-like inclusions immersed in a scattering and absorbing object are presented. The localization algorithm relies on distance ranging based on the measurement of early photons arrival times at different positions around the subject. This requires exquisite timing accuracy from the scanner. Further exploiting this capability, we show results on the effect of a scattering hetereogenity on the arrival time of early photons. These results demonstrate that our scanner provides all that is necessary for reconstructing images of small animals using full tomographic reconstruction algorithms, which will be the next step. Through its free-space optics design and the short pulse laser used, our scanner shows unprecedented timing resolution compared to other multi-view time-domain scanners.

  11. Ka波段DMTL移相器用RF MEMS电容式并联开关研制%Development of RF MEMS Capacitive Shunt Switch for Ka-Band DMTL Phase Shifter

    Institute of Scientific and Technical Information of China (English)

    高杨; 贾小慧; 秦燃; 官承秋

    2012-01-01

    A MEMS capacitive shunt switch for Ka-band 5-bit distributed MEMS transmission line (DMTL) phase shifter was presented in this paper.The structural dimensions of MEMS capacitive shunt switch were roughly defined by theoretical calculation and engineering experience.The 3D electromagnetic model of the switch was established,and the structural dimensions were optimized by using HFSS software.Simulation results show that the insertion loss of the switch was lower than 0.15 dB and the isolation loss was higher than 15 dB in Ka-band.The driving voltage of the switch was 2.1 V,which was obtained from the simulation of electromechanical coupling by using CoventorWare software.After several modifications of device layout and fabrication process according to the surface micro-machining process restriction of the foundry,preliminary MEMS capacitive shunt switch process sample was obtained.Dynamic characteristics of a single MEMS switch were tested.The results show that the height pulled down by microbridge was about 2 μm with 36 V driving voltage applied.There was a big difference between the tested driving voltage 36 V and the originally designed value 2.1 V,due to the temporary structural design modification according to the process restriction of the foundry.The modifications mainly involve increasing the microbridge height,and increasing the initial distance between the microbridge (top electrode) and the bottom electrode.%本文设计并制作了一种用于Ka波段分布式MEMS传输线(DMTL)移相器的MEMS电容式并联开关.通过理论计算和工程经验,大致定义了开关的结构尺寸.采用HFSS软件建立了开关的三维电磁场模型并优化了关键结构参数.仿真表明:开关在Ka波段插入损耗小于0.15 dB,回波损耗大于15 dB.采用CoventorWare软件进行了开关的机电耦合仿真,得出其驱动电压为2.1V.为了满足流片单位表面微加工工艺的约束,对开关的设计版图和微加工工艺进行了多轮改进,

  12. 一种Ka频段海上卫星通信抗雨衰编码方案%An anti-rain attenuation encoding solution for sea Ka-band satellite communication

    Institute of Scientific and Technical Information of China (English)

    高化猛; 李智

    2011-01-01

    The mechanism of rain attenuation in satellite communication and it's affection to Ka-band satellite communication are analyzed. CCSDS( 15,1/6)standard convolution code is recommended as channel code to anti-rain attenuation the performance of CCSDS( 15,1/6) standard convolution code is researched. The encoding efficiency is found by simulating encoding system in C translation environment. The decoding performance and encoding gain are found by simulating decoding system in BPSK modulation, ACWN channel, viterbi decoding algorithm. Simulation research demonstrates that the CCSDS (15, 1/6 ) standard convolution code is a good channel encoding solution for anti-rain attenuation in satellite communication on the sea because of high encoding velocity, high decoding performance and high encoding gain.%分析卫星通信雨衰现象的产生机制和对Ka频段卫星通信的影响,提出采用CCSDS标准卷积码作为抗雨衰编码方案.研究CCSDS(15,1/6)卷积码编译码性能:使用C语言编译环境,仿真CCSDS(15,1/6)编码系统,得出编码效率;使用二进制相移键控调制、加性高斯白噪声信道、维特比译码,仿真CCSDS(15,1/6)译码系统,得出译码性能和编码增益.仿真计算表明,CCSDS(15,1/6)具有编码速度快,译码性能好,编码增益高的特点,是一种好的海上卫星通信抗雨衰编码方案.

  13. 可用于产生微波信号的间隔可调双波长光纤激光器%Dual-wavelength fiber laser for generating interval-adjustable microwave

    Institute of Scientific and Technical Information of China (English)

    徐雨萌; 王国政; 彭玲玲; 刘昕男; 寇艳强; 吴柯鑫

    2014-01-01

    为了获得不同间隔双波长信号输出,提出一种基于受激布里渊效应产生双波长激光的实验装置,利用不同间隔双波长输出信号进行拍频实验可获得可调的微波信号输出;利用一段10 km长普通单模光纤(SM F)作为布里渊增益介质,一个线宽为5 kHz分布反馈激光器(DFB)作为布里渊抽运源,一段未泵浦的保偏掺铒光纤用作饱和吸收体抑制边模,通过改变未泵浦保偏掺铒光纤的长度,可获得不同间隔输出的双波长光纤激光器,实验获得波长间隔为0.170 nm和0.085 nm的激光信号输出,分别对应20 G Hz和10 G Hz的微波信号。%In order to obtain dual-wavelength output with different intervals ,an equipment to generate dual-wavelength laser based on simulated Brillouin effect was put up .The tunable microwave signal was got through beat frequency experiment for the different intervals dual-wavelength output signal .A segment of 10 km single-mode fiber (SMF) was used as the Bril-louin gain medium and a 5 kHz distributed feedback (DFB) semiconductor laser was used as the Brillouin pump (BP) .An un-pumped polarization maintaining erbium-doped fiber (PM-EDF) was used as the saturable absorber to suppress unwanted side-modes .Different-interval dual-wavelength output was obtained by changing the length of un-pumped PM-EDF .In the experiment ,dual-wavelength outputs with 0 .170 nm and 0 .085 nm spacing were achieved , corresponding to 20 GHZ and 10 GHZ microwave signals .

  14. A low-cost FMCW radar for footprint detection from a mobile platform

    Science.gov (United States)

    Boutte, David; Taylor, Paul; Hunt, Allan

    2015-05-01

    Footprint and human trail detection in rugged all-weather environments is an important and challenging problem for perimeter security, passive surveillance and reconnaissance. To address this challenge a low-cost, wideband, frequency-modulated continuous wave (FMCW) radar operating at 33.4GHz - 35.5GHz is being developed through a Department of Homeland Security Science and Technology Directorate Phase I SBIR and has been experimentally demonstrated to be capable of detecting footprints and footprint trails on unimproved roads in an experimental setting. It uses a low-cost digital signal processor (DSP) that makes important operating parameters reconfigurable and allows for frequency sweep linearization, a key technique developed to increase footprint signal-to-noise ratio (SNR). This paper discusses the design, DSP implementation and experimental results of a low-cost FMCW radar for mobile footprint detection. A technique for wideband sweep linearization is detailed along with system performance metrics and experimental results showing receive-SNR from footprint trails in sand and on unimproved dirt roads. Results from a second stepped frequency CW (SFCW) Ka-band system are also shown, verifying the ability of both systems to detect footprints and footprint trails in an experimental setting. The results show that there is sufficient receive-SNR to detect even shallow footprints (~1cm) using a radar based detection system in Ka-band. Field experimental results focus on system proof of concept from a static position with mobile results also presented highlighting necessary improvements to both systems.

  15. Dual-wavelength laser speckle imaging for monitoring brain metabolic and hemodynamic response to closed head traumatic brain injury in mice

    Science.gov (United States)

    Kofman, Itamar; Abookasis, David

    2015-10-01

    The measurement of dynamic changes in brain hemodynamic and metabolism events following head trauma could be valuable for injury prognosis and for planning of optimal medical treatment. Specifically, variations in blood flow and oxygenation levels serve as important biomarkers of numerous pathophysiological processes. We employed the dual-wavelength laser speckle imaging (DW-LSI) technique for simultaneous monitoring of changes in brain hemodynamics and cerebral blood flow (CBF) at early stages of head trauma in a mouse model of intact head injury (n=10). For induction of head injury, we used a weight-drop device involving a metal mass (˜50 g) striking the mouse's head in a regulated manner from a height of ˜90 cm. In comparison to baseline measurements, noticeable dynamic variations were revealed immediately and up to 1 h postinjury, which indicate the severity of brain damage and highlight the ability of the DW-LSI arrangement to track brain pathophysiology induced by injury. To validate the monitoring of CBF by DW-LSI, measurements with laser Doppler flowmetry (LDF) were also performed (n=5), which confirmed reduction in CBF following injury. A secondary focus of the study was to investigate the effectiveness of hypertonic saline as a neuroprotective agent, inhibiting the development of complications after brain injury in a subgroup of injured mice (n=5), further demonstrating the ability of DW-LSI to monitor the effects upon brain dynamics of drug treatment. Overall, our findings further support the use of DW-LSI as a noninvasive, cost-effective tool to assess changes in hemodynamics under a variety of pathological conditions, suggesting its potential contribution to the biomedical field. To the best of our knowledge, this work is the first to make use of the DW-LSI modality in a small animal model to (1) investigate brain function during the critical first hour of closed head injury trauma, (2) correlate between injury parameters of LDF measurements, and (3

  16. Assessment of crop foliar nitrogen using a novel dual-wavelength laser system and implications for conducting laser-based plant physiology

    Science.gov (United States)

    Eitel, Jan U. H.; Magney, Troy S.; Vierling, Lee A.; Dittmar, Günter

    2014-11-01

    Advanced technologies for improved nitrogen (N) fertilizer management are paramount for sustainably meeting future food demands. Green laser systems that measure pulse return intensity can provide more reliable information about foliar N than can traditional passive remote sensing devices during the critical early crop growth stages (e.g., before canopy closure when vegetation and soil signals are spectrally mixed) when further decisions regarding N management can be made. However, current green laser systems are not designed for agricultural applications and only employ a single green laser wavelength, which may limit applications because many factors that require normalization techniques can affect pulse return intensity. Here, we describe the design of a tractor-mountable, green (532 nm)- and red (658 nm) dual wavelength laser system and evaluate the potential of an additional red reference wavelength to improve laser based estimates of foliar N by calculating laser spectral indices based on ratio combinations of green laser return intensity (GLRI) and red laser return intensity (RLRI). We hypothesized that such laser spectral indices aid in accounting for factors that confound laser based foliar N estimates including variations in leaf angle, measurement distance, soil returns, and mixed edge returns. Leaf level measurements in winter wheat (Triticum aestivum) revealed that the two laser spectral indices improved the relationship with foliar N (r2 > 0.71, RMSE foliar N and laser spectral indices observed when employing the laser system under field conditions. In fact, the strongest relationship at the field canopy level was shown for GLRI (r2 = 0.65, RMSE = 0.37%) alone. Laboratory measurements suggest that the better performance of GLRI compared to ratio-based laser spectral indices may result from pronounced differences in the leaf-level bidirectional reflectance distribution factor (BRDFleaf) between the green and red laser wavelengths, thus confounding leaf

  17. 铬天青双波长法测定铁、镍含量实验设计%Content Determination of Iron & Nickel with Dual Wavelength Method

    Institute of Scientific and Technical Information of China (English)

    李娟; 李青青

    2015-01-01

    The contents of iron and nickel are determined by using chromazurine as chromogenic agent and cetyl trimethylamine bromide as sensitization with a dual wavelength method. Option 477. 00 nm and 480. 00 nm and 496. 00 nm for measuring wavelength. Fe-CAS,the Ni-CAS molar absorption coefficient at λ=480. 00 nm,respectively scope comply with the law of bill. The absorbance of the determination of mixed solutions at 477. 00 nm and 480. 00 nm and 496. 00 nm,the absorbance difference of the Fe-CAS at 477. 00 nm and 496. 00 nm are calculated,and with linear regression equation ,the Fe3+concentration is also computed;and by Fe3+ and Ni2+ at 480. 00 nm,unary linear regression equation the Ni2+ concentration is obtained.%通过设计一个以铬天青为显色剂,溴化十六烷基三甲胺为增敏剂,运用双波长法同时测定铁、镍含量的实验方法.并探究了该方法的最适测定条件,确定477.00 nm、480.00 nm、496.00 nm为测定波长.计算出Fe-CAS、Ni-CAS在480.00 nm处摩尔吸收系数,测定混合样品溶液在确定波长下的吸光度,并计算出 Fe-CAS在477.00 nm与496.00 nm处的吸光度差值;通过线性回归方程计算出Fe3+的浓度;再通过Fe3+、Ni2+在480.00 nm处的一元线性回归方程计算出Ni2+的浓度.

  18. 双波长分光光度法测定牛奶中的钙%Determination of Calcium in Milk by Dual Wavelength Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    姚文红; 徐香

    2012-01-01

    The calcium content in milk was detected by dual wavelength spectrophotometric method. Chrome black T(EBT) was used as the color reagent, in pHl0.0 buffer solution of ammonia, calcium reacted with EBT-polyethylene glycol to form a stable complex(l : 1). The interference of EBT was eliminated by double wave absorption and elimination technique. At wavelength of 558 nm and 645 nm, the absorbance difference A A was detected and the calcium content obeyed Bee' s law in 0-4,8 μg/mL. The linear regression equation was A A=0.069 64c +0.009 86, with correlation coefficient of 0.998 9. The sample was treated with dry ashing method, the content of calcium in the sample was abtained by detecting △A. The relative standard deviation of this method was L7%-7.6% and the average recovery was 79,0%-98.7%.%采用双波长分光光度法测定牛奶中钙离子的含量.基于在碱性缓冲液中,钙与铬黑T(EBT)-聚乙二醇溶液作用形成1∶1的配合物,利用等吸收双波长消去法,消除EBT自身的干扰.在558 nm和645 nm处测定,得吸光度差△A,钙的质量浓度在0~4.8μg/mL范围内符合比耳定律,线性回归方程为△A=0.06964c+0.00986,r=0.9989.用干灰化法处理样品,通过测定样品的△A,查得样品中钙离子的含量.该方法测定结果的相对标准偏差为1.7%~7.6%(n=5),平均加标回收率为79.0%~98.7%.

  19. Simultaneous Determinantion of Copper and Zinc in Water by Dual - wavelength Spectrophotometric%双波长光度法测定水中铜锌的含量

    Institute of Scientific and Technical Information of China (English)

    李娟; 王丽

    2016-01-01

    建立了一种以双波长光度法同时测定水中铜锌含量的分析方法.以铬黑 T(EBT)为显色剂,十六烷基三甲基溴化铵(CTMAB)为增敏剂,通过试验确定了最佳实验条件.结果表明,在 pH =9的硼酸-氯化钾-氢氧化钠缓冲溶液体系中,铜与锌都能与铬黑 T 显色剂形成稳定的紫红色络合物.铜络合物和锌络合物在540 nm 处的摩尔吸收系数分别为15284 L·(mol·cm)-1,16438 L·(mol·cm)-1,都在0~1.2 mg·L -1遵循比尔定律.%An analytic method of dual - wavelength Spectrophotometry to simultaneously determine the copper and zinc content in water was established. In the experiments with Eriochrome black T(short as EBT)as chromo-genic agent and CTMAB as sensitizer,the optimum experimental conditions were confirmed. Results showed that in the presence of H2 B4 O7 - KCl - NaOH medium at pH = 9 and the surfactant CTMAB,Cu(II)and Zn(II)react simultaneously with EBT forming the respective complexes Cu - R(λMAx = 531 nm)and Zn - R(λMAx = 547 nm). The amount of Cu(II)and Zn(II)were determined at wavelength of 540 nm isosbestic point ,which the molar ab-sorbtion coefficient,respectively 15 284 L·mol - 1 and 16 438 L·mol - 1 in 0 ~1. 2 mg·L - 1 ,followed beerˊs law.

  20. Design of a Ka-band 10 W Adaptive RF Predistortion Linearization Power Amplifier%Ka频段10W自适应射频预失真线性化固态功放研制

    Institute of Scientific and Technical Information of China (English)

    李凯; 张科; 张能波

    2014-01-01

    The characteristic of radio frequency power amplifier ( RFPA) will change with the channel switching,environment temperature,working conditions and other factors. In order to guarantee the steady operation of the predistortion RFPA,the predistortion system with adaptive performance is very important. This paper proposes a detection method of adaptive feedback,and uses the multidirectional search algorithm to minimize the amplitude distortion and phase distortion of the RFPA′s output signal to optimize the pre-distortion system,to make the system operate in optimum state all the time. An adaptive RF predistortion linearization solid-state power amplifier operating at the Ka-band is developed. In 3 GHz operation fre-quency band,the three-order intermodulation of the developed RFPA is effectively enhanced to be better than -32 dBc at -40℃ ~ 60℃. The test results show that the power amplifier has the characteristics of wide operation frequency band and wide temperature adaptability.%射频功率放大器的特性会随信道切换、环境温度、工作状态等多种因素发生变化,为了保证功率放大器的优良工作特性,具有自适应性能的预失真系统就显得非常重要。提出了一种自适应反馈检测方法,以减小放大器输出信号的幅度失真和相位失真作为系统自适应的优化目标,采用多方向搜索优化算法对预失真系统进行优化调整,使系统始终处于最优工作状态。研制了工作于 Ka 频段10 W自适应射频预失真线性化固态功放原理样机,当工作温度为-40℃~+60℃时,在3 GHz的工作带宽内,三阶交调指标优于-32 dBc。测试结果表明该功放具有工作频带宽、温度适应性广等特点。

  1. Dual wavelength capillary electrophoresis fingerprints of Shuanghuanglian Jiaonang%双黄连胶囊双波长毛细管电泳指纹图谱研究

    Institute of Scientific and Technical Information of China (English)

    孙国祥; 王建会; 吴玉

    2012-01-01

    目的 建立双黄连胶囊( Shuanghuanglian Jiaonang,SHLJN)双波长高效毛细管电泳指纹图谱(DW CEFP).方法 用三角形和四面体优化法优化出以50 mmol·L-1硼砂(含20 mmol·L-1β-环湖精和5%乙腈,磷酸调pH 7.55)为背景电解质(BGE),采用未涂层石英毛细管(75 cm×75 μm,有效分离长度57 cm),以色谱指纹图分离量指数(RF)为目标函数优化试验条件,运行电压12 kV,检测波长203 nm和256 nm.用均值法整合双波长谱的宏定性宏定量信息,用一级系统指纹定量法评价SHLJN质量.结果 以连翘苷(FST)为参照物峰,在203 nm和256 nm下检测,分别确定16和11个共有指纹峰,建立了DW-CEFP.用均值法整合后进行评价出S9样品质量极好,S2、S3、S4和S6样品质量很好,S1、S7、S10和S11样品质量好,S5、S8和S12样品质量良好.结论 基于双波长谱的一级系统指纹定量法对SHLJN整体定性定量分析具有信息全面、准确可靠的特点,为其质量控制提供一种新参考.%Objective To establish dual wavelength capillary electrophoresis fingerprints (DW-CEFP) for Shuanghuan-glian Jiaonang (SHLJN). Methods The 75 cm × 75 μm (the effective length of 57 cm) uncoated fused silica capillary column was used. The triangle and tetrahedron optimization method was employed to select the background electrolyte of 50 mmol · L-1 sodium borate, containing 20 mmol · L-1 β-cyclodextyin and 5% acetonitrile (pH adjusted to 7. 55 with phosphoric acid), and the running voltage was 12 kV, in which the detection wavelength was 203 nm and 256 nm. At the same time the chromatographic fingerprint resolution index was applied to optimize the CEFP conditions. The first systematically quantified fingerprint method (FSQFM) was used to evaluate SHLJN quality. The average method was used to integrate different chemical qualitative and quantitative information from the DW-CEFPs. Results The DW-CEFPs were developed, in which 16 and 11 co possessing peaks were marked

  2. 双波长皮秒脉冲与可调谐脉宽产生的实验研究%Experimental study about generation of picosecond pulses with dual-wavelengths and tunable pulse-widths

    Institute of Scientific and Technical Information of China (English)

    郭志华; 罗春娅; 李丹; 凌福日

    2016-01-01

    In order to improve the practicability of multi-wavelength optical pulse equipment , a stable dual-wavelength semiconductor fiber ring laser was proposed and demonstrated by using dual-wavelength principle . Effects of ring cavity dispersion, filter pulse-width and modulation depth on output pulse were discussed .Experimental results are that repetition rate of dual-wavelength pulses is 5.0GHz and typical pulse-width is 20ps.Dual-wavelength pulses have good side-mode suppression ratios of 29.1dB ( at 1554.75nm) and 29.7dB ( at 1557.21nm) with typical output powers of -6.7dBm and -6.1dBm respectively.Output spectra are very stable with peak power fluctuation less than 0.5dB.This study is of great significance for the study of terahertz source and multi-wavelength optical pulse equipment .%为了提高多波长光脉冲设备的实用性,采用双波长工作原理,设计了一种稳定的双波长半导体环形光纤激光器. 讨论了环形腔色散、滤波器脉宽以及调制深度等对输出脉冲的影响. 结果表明,双波长光脉冲的重复率为5.0GHz,典型脉宽为20ps,双波长光脉冲具有良好的边模抑制比,当输出波长为1554.75nm和1557.21nm时,边模抑制比分别为29.1dB和29.7dB,其典型的输出功率分别为-6.7dBm和-6.1dBm,输出光谱的峰值功率波动小于0.5dB. 这项研究对太赫兹源和多波长光脉冲设备的研究具有借鉴意义.

  3. A Cloud and Precipitation Radar System Concept for the ACE Mission

    Science.gov (United States)

    Durden, S. L.; Tanelli, S.; Epp, L.; Jamnejad, V.; Perez, R.; Prata, A.; Samoska, L.; Long, E; Fang, H.; Esteban-Fernandez, D.; Lee, C.

    2011-01-01

    One of the instruments recommended for deployment on the Aerosol/Cloud/Ecosystems (ACE) mission is a new advanced cloud profiling radar. In this paper, we describe such a radar design, called ACERAD, which has 35- and 94-GHz channels, each having Doppler and dual-polarization capabilities. ACERAD will scan at Ka-band and will be nadir-looking at W-band. To get a swath of 25-30 km, considered the minimum useful for Ka-band, ACERAD needs to scan at least 2 degrees off nadir; this is at least 20 beamwidths, which is quite large for a typical parabolic reflector. This problem is being solved with a Dragonian design; a scaled prototype of the antenna is being fabricated and will be tested on an antenna range. ACERAD also uses a quasi-optical transmission line at W-band to connect the transmitter to the antenna and antenna to the receiver. A design for this has been completed and is being laboratory tested. This paper describes the current ACERAD design and status.

  4. A 35-GHz Polarimetric Doppler Radar and Its Application for Observing Clouds Associated with Typhoon Nuri

    Institute of Scientific and Technical Information of China (English)

    ZHONG Lingzhi; LIU Liping; FENG Sheng; GE Runsheng; ZHANG Zhe

    2011-01-01

    Millimeter-wavelength radar has proved to be an effective instrument for cloud observation and research.In this study, 8-mm-wavelength cloud radar (MMCR) with Doppler and polarization capabilities was used to investigate cloud dynamics in China for the first time. Its design, system specifications, calibration,and application in measuring clouds associated with typhoon are discussed in this article. The cloud radar measurements of radar refiectivity (Z), Doppler velocity (Vr), velocity spectrum width (Sw) and the depolarization ratio (LDR) at vertical incidence were used to analyze the microphysical and dynamic processes of the cloud system and precipitation associated with Typhoon Nuri, which occurred in southern China in August 2008. The results show the refiectivity observed using MMCR to be consistent with the echo height and the melting-layer location data obtained by the nearby China S-band new-generation weather radar (SA),but the Ka-band MMCR provided more detailed structural information about clouds and weak precipitation data than did the SA radar. The variation of radar refiectivity and LDR in vertical structure reveals the transformation of particle phase from ice to water. The vertical velocity and velocity spectrum width of MMCR observations indicate an updraft and strong turbulence in the stratiform cloud layer. MMCR provides a valuable new technology for meteorological research in China.

  5. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  6. Optical Design of F- theta Lens for Dual Wavelength Selective Laser Melting%双波长选区激光熔化成形中F-theta镜头光学设计

    Institute of Scientific and Technical Information of China (English)

    冯联华; 张宁; 曹洪忠; 徐熙平; 段宣明

    2016-01-01

    F-theta lens is an important unit for selective laser melting (SLM) manufacture and generally use a single wavelength as the light source. The dual wavelength f-theta lens has not been used in SLM manufacture. In order to improve the SLM formability, we present the design of the f-theta lens satisfied coaxial dual wavelength SLM manu-facture. Linear scanning was achieved by introducing negative distortion, and chromatic aberration correction was achieved by choosing appropriate glass material and the structural optimization. It is composed of three pieces of spheri-cal lenses. In the scan area of 120mm × 120mm, the focal spots for 532nm laser and 1080nm laser are smaller than 30μm and 60μm,respectively. The lateral color of the designed f-theta lens is less than 1μm between the two wave-lengths,which meet the high precision application requirements of dual wavelength selective laser melting.%在选区激光熔化成形设备中,F-theta镜头是其重要的组成单元,一般采用单一波长作为光源。为了改善选区激光熔化成形性能,首次设计了由三片球面透镜组成的用于共轴双波长选区激光熔化成形的f-theta镜头。通过引入负畸变实现线性扫描,并选择合适玻璃材料、结构设计来消除色差。在扫描面积为120mm×120mm范围内,适用激光波长为532nm和1080nm,对这两波长激光的聚焦光斑分别小于30μm和60μm,横向色差分离小于1μm,满足高精度双波长激光同时共轴选区熔化成形的应用需求。

  7. Radar Chart

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Radar Chart collection is an archived product of summarized radar data. The geographic coverage is the 48 contiguous states of the United States. These hourly...

  8. Comment on "Dual-wavelength in-line phase-shifting interferometry based on two dc-term-suppressed intensities with a special phase shift for quantitative phase extraction"

    CERN Document Server

    Wang, Minmin; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie

    2016-01-01

    We comment on the recent Letter by Xu and Wang et al. [Opt. Lett. 41, 2430 (2016)] in which an approach of quantitative phase extraction in dual-wavelength in-line phase-shifting interferometry (DWILPSI) was proposed. It is noted that a special phase shift is used, which more or less embarrasses its practical operation. We wish to show that the same result can also be reached by combining the generalized phase-shifting algorithm and the least-square algorithm, in which the phase shift can be chosen randomly. In addition to maintaining high accuracy and rapid processing speed of the DWILPSI method, the proposed method greatly facilitates its application in actual measurement.

  9. ER-2 Airborne Radars Data during Iphex - a New 4-Frequency Look at Precipitation.

    Science.gov (United States)

    Heymsfield, G. M.; Tian, L.; McLinden, M.; Li, L.; Cervantes, J.; Venkatesh, V.; Coon, M.

    2014-12-01

    The Integrated Precipitation and Hydrology Experiment (IPHEx) field campaign was conducted in the Southeast U.S. from 15 May to 30 June 2014 in support of Global Precipitation Mission (GPM) ground validation. The NASA ER-2 flew in this campaign as a GPM simulator with radars and radiometers that covered the Dual-frequency Precipitation Radar (DPR) and GPM Microwave Imager (GMI) frequencies. The main goal for the ER-2 high spatial and temporal resolution data sets to be used for GPM algorithm validation and improvement. Goddard Space Flight Center provided 3 nadir-pointing radars that covered X- through W-band. The High-altitude Wind and Rain Airborne Profiler (HIWRAP) provided Ku and Ka-band measurements that are similar to GPM's DPR. In addition, the W-band Cloud Radar System (CRS) and ER-2 X-band Radar (EXRAD) were on board. The 4 frequencies provide opportunity for developing consistent retrieval algorithms as well as to expand the dynamic range (i.e., particle size) of the retrievals. There were a total of 15 science flights during IPHEx that measured a variety of land-based and oceanic precipitation, with may convective, stratiform, and cloud targets. This presentation will provide preliminary observations and analyses from the IPHEx ER-2 radars. It will discuss planned retrieval algorithms and data analyses.

  10. Radar Fundamentals, Presentation

    OpenAIRE

    Jenn, David

    2008-01-01

    Topics include: introduction, radar functions, antennas basics, radar range equation, system parameters, electromagnetic waves, scattering mechanisms, radar cross section and stealth, and sample radar systems.

  11. Radar Fundamentals, Presentation

    OpenAIRE

    Jenn, David

    2008-01-01

    Topics include: introduction, radar functions, antennas basics, radar range equation, system parameters, electromagnetic waves, scattering mechanisms, radar cross section and stealth, and sample radar systems.

  12. Radar equations for modern radar

    CERN Document Server

    Barton, David K

    2012-01-01

    Based on the classic Radar Range-Performance Analysis from 1980, this practical volume extends that work to ensure applicability of radar equations to the design and analysis of modern radars. This unique book helps you identify what information on the radar and its environment is needed to predict detection range. Moreover, it provides equations and data to improve the accuracy of range calculations. You find detailed information on propagation effects, methods of range calculation in environments that include clutter, jamming and thermal noise, as well as loss factors that reduce radar perfo

  13. A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

    Science.gov (United States)

    Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

    2014-05-01

    One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform

  14. ARM Cloud Radar Simulator Package for Global Climate Models Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuying [North Carolina State Univ., Raleigh, NC (United States); Xie, Shaocheng [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-05-01

    It has been challenging to directly compare U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility ground-based cloud radar measurements with climate model output because of limitations or features of the observing processes and the spatial gap between model and the single-point measurements. To facilitate the use of ARM radar data in numerical models, an ARM cloud radar simulator was developed to converts model data into pseudo-ARM cloud radar observations that mimic the instrument view of a narrow atmospheric column (as compared to a large global climate model [GCM] grid-cell), thus allowing meaningful comparison between model output and ARM cloud observations. The ARM cloud radar simulator value-added product (VAP) was developed based on the CloudSat simulator contained in the community satellite simulator package, the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP) (Bodas-Salcedo et al., 2011), which has been widely used in climate model evaluation with satellite data (Klein et al., 2013, Zhang et al., 2010). The essential part of the CloudSat simulator is the QuickBeam radar simulator that is used to produce CloudSat-like radar reflectivity, but is capable of simulating reflectivity for other radars (Marchand et al., 2009; Haynes et al., 2007). Adapting QuickBeam to the ARM cloud radar simulator within COSP required two primary changes: one was to set the frequency to 35 GHz for the ARM Ka-band cloud radar, as opposed to 94 GHz used for the CloudSat W-band radar, and the second was to invert the view from the ground to space so as to attenuate the beam correctly. In addition, the ARM cloud radar simulator uses a finer vertical resolution (100 m compared to 500 m for CloudSat) to resolve the more detailed structure of clouds captured by the ARM radars. The ARM simulator has been developed following the COSP workflow (Figure 1) and using the capabilities available in COSP

  15. Planetary Radar

    Science.gov (United States)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  16. Rain Rate-Radar Reflectivity Relationship for Drop Size Distribution and Rain Attenuation Calculation of Ku Band Signals

    Directory of Open Access Journals (Sweden)

    Govardhani.Immadi

    2014-05-01

    Full Text Available With the increased demand for long distance Tele communication day by day, satellite communication system was developed. Satellite communications utilize L, C, Ku and Ka bands of frequency to fulfil all the requirements. Utilization of higher frequencies causes severe attenuation due to rain. Rain attenuation is noticeable for frequencies above 10ghz. Amount of attenuation depends on whether the operating wave length is comparable with rain drop diameter or not. In this paper the main focus is on drop size distribution using empirical methods, especially Marshall and Palmer distributions. Empirical methods deal with power law relation between the rain rate(mm/h and radar reflectivity(dBz. Finally it is discussed about the rain rate variation, radar reflectivity, drop size distribution, that is made for two rain events at K L University, Vijayawada on 4th September 2013 and on 18 th August 2013.

  17. An Unattended Cloud-Profiling Radar for Use in Climate Research.

    Science.gov (United States)

    Moran, Kenneth P.; Martner, Brooks E.; Post, M. J.; Kropfli, Robert A.; Welsh, David C.; Widener, Kevin B.

    1998-03-01

    A new millimeter-wave cloud radar (MMCR) has been designed to provide detailed, long-term observations of nonprecipitating and weakly precipitating clouds at Cloud and Radiation Testbed (CART) sites of the Department of Energy's Atmospheric Radiation Measurement (ARM) program. Scientific requirements included excellent sensitivity and vertical resolution to detect weak and thin multiple layers of ice and liquid water clouds over the sites and long-term, unattended operations in remote locales. In response to these requirements, the innovative radar design features a vertically pointing, single-polarization, Doppler system operating at 35 GHz (Ka band). It uses a low-peak-power transmitter for long-term reliability and high-gain antenna and pulse-compressed waveforms to maximize sensitivity and resolution. The radar uses the same kind of signal processor as that used in commercial wind profilers. The first MMCR began operations at the CART in northern Oklahoma in late 1996 and has operated continuously there for thousands of hours. It routinely provides remarkably detailed images of the ever-changing cloud structure and kinematics over this densely instrumented site. Examples of the data are presented. The radar measurements will greatly improve quantitative documentation of cloud conditions over the CART sites and will bolster ARM research to understand how clouds impact climate through their effects on radiative transfer. Millimeter-wave radars such as the MMCR also have potential applications in the fields of aviation weather, weather modification, and basic cloud physics research.

  18. Cynergy双波长激光治疗儿童皮肤血管性病变的疗效分析%Curative effect of Cynergy dual wavelength laser in treatment of skin vascular pathological changes in children

    Institute of Scientific and Technical Information of China (English)

    李永红; 黄一锦; 林维嘉; 张启国; 柯晓苹; 赵小燕

    2013-01-01

    目的 探讨Cynergy双波长激光治疗儿童皮肤血管性病变的疗效和不良反应.方法 采用Cynergy双波长(595 nm和1064 nm)激光,对儿童皮肤血管性病变650例(草莓状血管瘤398例,鲜红斑痣252例)进行治疗,能量密度分别为5~15 J/cm2和30~80 J/cm2.并对其治疗效果及不良反应,以及鲜红斑痣疗效与患者年龄、部位、皮损颜色的关系进行分析.结果 650例患者在适合的脉宽及能量密度下,经过3~7次治疗,草莓状血管瘤有效率92.2%,粉红型鲜红斑痣有效率77.9%,紫红型鲜红斑痣有效率38.9%,增厚型鲜红斑痣有效率14.3%,总体不良反应发生率2.3%.经x2检验,鲜红斑痣疗效因患者年龄、部位、皮损颜色而异,患者年龄越小,皮损颜色越浅,疗效越好,眶周疗效好于额面和四肢.结论 Cynergy双波长激光治疗儿童皮肤血管性病变,疗效显著,不良反应轻,是一种新的治疗技术,安全、可靠,值得推广应用.%Objective To explore the curative effect and adverse reactions through Cynergy dual wavelength laser to cure skin vascular pathological changes in children.Methods Cynergy dual wavelength (595 nm and 1064 nm) laser were used to treat the skin vascular pathological changes in children (650 cases) including strawberry-shaped hemangioma (398 cases) and port wine stain (252 cases).Anergy density was 5-15 J/cm2 and 30-80 J/cm2.The curative effect and adverse reaction and also the relationship between the port wine stain curative effect and the age of patient,location,and colour of skin lesions were analyzed.Results In total 650 cases after 3-7 times treatments under suitable pulse width and energy density,the curative effect for strawberry-shaped hemangioma was 92.2 %,that for pink type port wine stain was 77.9 %,that for purple type port wine stain was 38.9 %,and that for thickening type port wine stain was 14.3 % ; the overall adverse reaction rate was 2.3 %.After test with x2 analysis

  19. Improvement of signal-to-noise ratio of optoacoustic signals from double-walled carbon nanotubes by using an array of dual-wavelength high-power diode lasers

    Science.gov (United States)

    Leggio, Luca; de Varona, Omar E.; Escudero, Pedro; Carpintero del Barrio, Guillermo; Osiński, Marek; Lamela Rivera, Horacio

    2015-07-01

    Optoacoustic (OA) imaging is a rising biomedical technique that has attracted much interest over the last 15 years. This technique permits to visualize the internal soft tissues in depth by using short laser pulses, able to generate ultrasonic signals in a large frequency range. It combines the high contrast of optical imaging with the high resolution of ultrasound systems. The OA signals detected from the whole surface of the body serve to reconstruct in detail the image of the internal tissues, where the absorbed optical energy distribution outlines the regions of interest. In fact, the use of contrast agents could improve the detection of growing anomalies in soft tissues, such as carcinomas. This work proposes the use of double-walled carbon nanotubes (DWCNTs) as a potential nontoxic biodegradable contrast agent applicable in OA to reveal the presence of malignant in-depth tissues in near infrared (NIR) wavelength range (0.75-1.4 μm), where the biological tissues are fairly transparent to optical radiation. A dual-wavelength (870 and 905 nm) OA system is presented, based on arrays of high power diode lasers (HPDLs) that generate ultrasound signals from a DWCNT solution embedded within a biological phantom. The OA signals generated by DWCNTs are compared with those obtained using black ink, considered to be a very good absorber at these wavelengths. The experiments prove that DWCNTs are a potential contrast agent for optoacoustic spectroscopy (OAS).

  20. Prospective Comparison of Dual Wavelength Long-Pulsed 755-nm Alexandrite/1,064-nm Neodymium:Yttrium-Aluminum-Garnet Laser versus 585-nm Pulsed Dye Laser Treatment for Rosacea

    Science.gov (United States)

    Seo, Hyun-Min; Kim, Jung-In; Kim, Han-Saem; Choi, Young-Jun

    2016-01-01

    Background Rosacea treatments including oral/topical medications and laser therapy are numerous but unsatisfactory. Objective To compare the effectiveness of the dual wavelength long-pulsed 755-nm alexandrite/1,064-nm neodymium: yttrium-aluminum-garnet laser (LPAN) with that of 585-nm pulsed dye laser (PDL) for rosacea. Methods This was a randomized, single-blinded, comparative study. Full face received four consecutive monthly treatments with LPAN or PDL, followed-up for 6 months after the last treatment. Erythema index was measured by spectrophotometer, and digital photographs were evaluated by consultant dermatologists for physician's global assessment. Subjective satisfaction surveys and adverse effects were recorded. Results Forty-nine subjects with rosacea enrolled and 12 dropped out. There were no significant differences between LPAN and PDL in the mean reduction of the erythema index (p=0.812; 3.6% vs. 2.8%), improvement of physician's global assessment (p=1.000; 88.9% vs. 89.5%), and subject-rated treatment satisfaction (p=0.842; 77.8% vs. 84.2%). PDL showed more adverse effects including vesicles than LPAN (p=0.046; 26.3% vs. 0.0%). No other serious or permanent adverse events were observed in both treatments. Conclusion Both LPAN and PDL may be effective and safe treatments for rosacea. PMID:27746641

  1. Performance of the Dual-frequency Precipitation Radar on the GPM core satellite

    Science.gov (United States)

    Iguchi, Toshio; Seto, Shinta; Awaka, Jun; Meneghini, Robert; Kubota, Takuji; Oki, Riko; Chandra, Venkatchalam; Kawamoto, Nozomi

    2016-04-01

    The GPM core satellite was launched on February 28, 2014. This paper describes some of the results of precipitation measurements with the Dual-Frequency Precipitation Radar (DPR) on the GPM core satellite. The DPR, which was developed by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT), consists of two radars: Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The performance of the DPR is evaluated by comparing the level 2 products with the corresponding TRMM/PR data and surface rain measurements. The scanning geometry and footprint size of KuPR and those of PR are nearly identical. The major differences between them are the sensitivity, visiting frequency, and the rain retrieval algorithm. KuPR's sensitivity is twice as good as PR. The increase of sensitivity reduces the cases of missing light rain. Since relatively light rain prevails in Japan, the difference in sensitivity may cause a few percentage points in the bias. Comparisons of the rain estimates by GPM/DPR with AMeDAS rain gauge data over Japan show that annual KuPR's estimates over Japan agree quite well with the rain gauge estimates although the monthly or local statistics of these two kinds of data scatter substantially. KuPR's esimates are closer to the gauge estimates than the TRMM/PR. Possible sources of the differences that include sampling errors, sensitivity, and the algorithm are examined.

  2. Study on determination of pigments in food by single wavelength spectrophotometer and dual wavelength spectrophotometer%分光光度法测定食品色素含量的研究

    Institute of Scientific and Technical Information of China (English)

    杜建中; 李青梅; 卢冬梅; 朱艺强; 丁玎; 罗科丽; 谭永辉; 赖春莲

    2011-01-01

    The single wavelength spectrophotometer was used to determine both ponceaue and brilliant blue of beverage. The results showed a good linear relationship for ponceaue at 0.2 ~ 80mg/L and for brilliant blue at 0.1~2Omg/L, the recovery was between 98% and 108%. Both single wavelength and dual wavelength spectrophotometer were used to determine tartrazine and sunset yellow in beverage simultaneously. The results showed a good linear relationship for the tartrazine at O.l~7Omg/L and sunset yellow at O.2~60mg/L also,and the recovery was between 95% and 110%.The two methods were time efficient,accurate and easy to handle. The dual wavelength spectrophotometer was used to determine tartrazine, sunset yellow, and ponceaue in fruit- flavored soda. The results showed a good linear relationship for tartrazine at O.1~6Omg/L,sunset yellow at 0.8~90mg/L,and ponceaue at 0.2~80mg/L. The average recovery was 100.5% ,102.4% ,and 101.8% respectively.%采用单波长法对饮料中胭脂红和亮蓝含量进行测定,结果显示,胭脂红在0.2-80mg/L,亮蓝在0.1-20mg/L浓度范围具有良好线性关系,回收率在98%-108%,采用单波长法和双波长法相结合对饮料中酒石黄和日落黄含量进行测定,结果显示,酒石黄在0.1-70mg/L,日落黄在0.2-60mg/L浓度范围具有良好线性关系,回收率在95%a-110%.两种方法对样品检测快速、准确,且操作简便.利用双波长比值光谱法对果味汽水中酒石黄、日落黄、胭脂红含量进行测定,结果显示,酒石黄在0.1~60mg/L,日落黄在0.8-90mg/L,胭脂红在0.2-80mg/L.浓度范围内具有良好的线性关系,平均回收率分别为100.5%,102.4%和101.8%.

  3. Content Determination of Acetylsalicylic Acid Essel Cold Tablets by Dual Wavelength Spectrophotometry%双波长分光光度法测定爱索尔感冒片中乙酰水杨酸的含量

    Institute of Scientific and Technical Information of China (English)

    吴雪冬

    2014-01-01

    目的:建立双波长分光光度法测定爱索尔感冒片中乙酰水杨酸的含量的测定方法。方法样品操作及测定方法同重复性试验,平行操作5批样品,另按照中和滴定法测定,比较两种测定方法测定所得样品的百分标示量。结果双波长法:99.2%,97.9%,98.5%,96.5%,98.2%;中和法:100.8%,98.7%,99.8%,97.1%,99.4%。乙酰水杨酸在255nm的波长处有最大吸收,盐酸吗啉胍在250nm的波长附近为225nm波长的等吸收波长,经过精选,选择250.1nm波长为参比波长,225nm波长为测定波长。乙酰水杨酸乙醇溶液放置3h基本稳定,其他成分的乙醇溶液均稳定。结论采用双波长分光光度法测定爱索尔感冒片中乙酰水杨酸的含量,操作简单,所用试剂方便易得,通过两种试验方法的比较,效果较满意。%Objective To establish a method for determination of dual wavelength determination of acetylsalicylic acid essel cold tablets by spectrophotometry. Methods the sample operation and determination method with repeated experiments, paral el operation of 5 batches of samples, determination of the other in accordance with the neutralization titration method, comparison of two determination methods of the sample percent mark. Results The dual wavelength method: 99.2%, 97.9%, 98.5%, 96.5%, 98.2%; neutralization method: 100.8%, 98.7%, 99.8%, 97.1%, 99.4%. Acetyl salicylic acid has a maximum absorption at 255nm wavelength, Moroxydine Hydrochloride absorption wavelength, 225nm wavelength around 250nm wavelength selected, select the 250.1nm wavelength as the reference wavelength, the wavelength of 225nm as the detection wavelength. Acetyl salicylic acid ethanol solution for 3 hours basical y stable, other components are stable in ethanol solution. Conclusion The operation content, determined by double wavelength acetylsalicylic acid essel cold tablets by spectrophotometry is simple, the reagent is convenient and easy, by comparing the two kinds of test

  4. Weather Radar Stations

    Data.gov (United States)

    Department of Homeland Security — These data represent Next-Generation Radar (NEXRAD) and Terminal Doppler Weather Radar (TDWR) weather radar stations within the US. The NEXRAD radar stations are...

  5. Monolithic microwave integrated circuits for sensors, radar, and communications systems; Proceedings of the Meeting, Orlando, FL, Apr. 2-4, 1991

    Science.gov (United States)

    Leonard, Regis F. (Editor); Bhasin, Kul B. (Editor)

    1991-01-01

    Consideration is given to MMICs for airborne phased arrays, monolithic GaAs integrated circuit millimeter wave imaging sensors, accurate design of multiport low-noise MMICs up to 20 GHz, an ultralinear low-noise amplifier technology for space communications, variable-gain MMIC module for space applications, a high-efficiency dual-band power amplifier for radar applications, a high-density circuit approach for low-cost MMIC circuits, coplanar SIMMWIC circuits, recent advances in monolithic phased arrays, and system-level integrated circuit development for phased-array antenna applications. Consideration is also given to performance enhancement in future communications satellites with MMIC technology insertion, application of Ka-band MMIC technology for an Orbiter/ACTS communications experiment, a space-based millimeter wave debris tracking radar, low-noise high-yield octave-band feedback amplifiers to 20 GHz, quasi-optical MESFET VCOs, and a high-dynamic-range mixer using novel balun structure.

  6. Stratiform and Convective Precipitation Observed by Multiple Radars during the DYNAMO/AMIE Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Min; Kollias, Pavlos; Feng, Zhe; Zhang, Chidong; Long, Charles N.; Kalesse, Heike; Chandra, Arunchandra; Kumar, Vickal; Protat, Alain

    2014-11-01

    The motivation for this research is to develop a precipitation classification and rain rate estimation method using cloud radar-only measurements for Atmospheric Radiation Measurement (ARM) long-term cloud observation analysis, which are crucial and unique for studying cloud lifecycle and precipitation features under different weather and climate regimes. Based on simultaneous and collocated observations of the Ka-band ARM zenith radar (KAZR), two precipitation radars (NCAR S-PolKa and Texas A&M University SMART-R), and surface precipitation during the DYNAMO/AMIE field campaign, a new cloud radar-only based precipitation classification and rain rate estimation method has been developed and evaluated. The resulting precipitation classification is equivalent to those collocated SMART-R and S-PolKa observations. Both cloud and precipitation radars detected about 5% precipitation occurrence during this period. The convective (stratiform) precipitation fraction is about 18% (82%). The 2-day collocated disdrometer observations show an increased number concentration of large raindrops in convective rain compared to dominant concentration of small raindrops in stratiform rain. The composite distributions of KAZR reflectivity and Doppler velocity also show two distinct structures for convective and stratiform rain. These indicate that the method produces physically consistent results for two types of rain. The cloud radar-only rainfall estimation is developed based on the gradient of accumulative radar reflectivity below 1 km, near-surface Ze, and collocated surface rainfall (R) measurement. The parameterization is compared with the Z-R exponential relation. The relative difference between estimated and surface measured rainfall rate shows that the two-parameter relation can improve rainfall estimation.

  7. Bistatic radar

    CERN Document Server

    Willis, Nick

    2004-01-01

    Annotation his book is a major extension of a chapter on bistatic radar written by the author for the Radar Handbook, 2nd edition, edited by Merrill Skolnik. It provides a history of bistatic systems that points out to potential designers the applications that have worked and the dead-ends not worth pursuing. The text reviews the basic concepts and definitions, and explains the mathematical development of relationships, such as geometry, Ovals of Cassini, dynamic range, isorange and isodoppler contours, target doppler, and clutter doppler spread.Key Features * All development and analysis are

  8. Mobile Three Frequency Radar as Research Platform for Precipitation Profiling

    Science.gov (United States)

    Schmidt, Walter; Rautiainen, Kimmo; Harri, Ari-Matti

    2014-05-01

    Precipitation profiling at the frequency bands of Ku, Ka and W bands are becoming increasingly popular in the studies of atmospheric microphysics. Ever since the introduction of Ku / Ka pair of frequencies for the Global Precipitation Measurement mission (GPM) and the success of W band in Cloudsat, the interest in precipitation profiling using these frequencies has increased. The profiling observations will also serve as ground validation instruments for several space missions such as GPM and EarthCARE [1]. In order to get better information to retrieve ice microphysics as well as to enhance sensitivity, we need to move from the standard S- and C-band weather radars to higher frequencies [2]. As was recently shown, the use of multi- frequency profiling yields important additional information compared to single-frequency radar mapping [3]. During the past four years a consortium of research, academic and private industries in Finland has been developing a flexible low-cost mobile three-band radar system for precipitation profiling. The feasibility of the concept is being demonstrated by implementing the Ku- and Ka-band part of the system. The antenna structure with antennas for Ku-, Ka- and W-band is completed allowing the pointing of all three antenna systems into the same direction during an azimuth and elevation scan. Using a freely programmable digital waveform generator and decoding electronics for the received data, the implementation of different wave form generation, compression and decoding schemes and their influence on the radar performance in the different bands can be evaluated and optimized. The modular design allows the connection of different transmitter control and receiver decoding units to any of the three band front-end electronics to evaluate the performance of different approaches in the various bands simultaneously. A real-time analysis software supports the data interpretation and system optimization during field tests. Via mobile internet

  9. Radar detection

    CERN Document Server

    DiFranco, Julius

    2004-01-01

    This book presents a comprehensive tutorial exposition of radar detection using the methods and techniques of mathematical statistics. The material presented is as current and useful to today's engineers as when the book was first published by Prentice-Hall in 1968 and then republished by Artech House in 1980. The book is divided into six parts.

  10. Coherent resonant Ka-band photonic microwave receiver

    CERN Document Server

    Ilchenko, Vladimir S; Savchenkov, Anatoliy A; Seidel, David; Matsko, Andrey B; Maleki, Lute

    2008-01-01

    We propose theoretically and demonstrate experimentally a coherent microwave photonic receiver operating at 35 GHz carrier frequency. The device is based on a lithium niobate or lithium tantalate optical whispering gallery mode resonator coupled to a microwave strip line resonator. Microwave local oscillator is fed into the microwave resonator along with the microwave signal. We show that the sensitivity of this receiver significantly exceeds the sensitivity of the incoherent quadratic receiver based on the same technology. The coherent receiver can possess a dynamic range in excess of 100 dB in 5 MHz band if a low noise laser is utilized.

  11. Weather Forecasting for Ka-band Operations: Initial Study Results

    Science.gov (United States)

    Morabito, D.; Wu, L.; Slobin, S.

    2016-08-01

    As lower frequency bands (e.g., 2.3 GHz and 8.4 GHz) have become oversubscribed during the past several decades, NASA has become interested in using higher frequency bands (e.g., 26 GHz and 32 GHz) for telemetry, thus making use of the available wider bandwidth. However, these bands are more susceptible to atmospheric degradation. Currently, flight projects tend to be conservative in preparing their communications links by using worst-case or conservative assumptions. Such assumptions result in nonoptimum data return. We explore the use of weather forecasting for Goldstone and Madrid for different weather condition scenarios to determine more optimal values of atmospheric attenuation and atmospheric noise temperature for use in telecommunication link design. We find that the use of weather forecasting can provide up to 2 dB or more of increased data return when more favorable conditions are forecast. Future plans involve further developing the technique for operational scenarios with interested flight projects.

  12. High-Power Ka-Band Window and Resonant Ring

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2006-11-29

    A stand-alone 200 MW rf test station is needed for carrying out development of accelerator structures and components for a future high-gradient multi-TeV collider, such as CLIC. A high-power rf window is needed to isolate the test station from a structure element under test. This project aimed to develop such a window for use at a frequency in the range 30-35 GHz, and to also develop a high-power resonant ring for testing the window. During Phase I, successful conceptual designs were completed for the window and the resonant ring, and cold tests of each were carried out that confirmed the designs.

  13. Miniature Ka-band Automated Swath Mapper (KASM) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal discusses the development and demonstration of a swath-based airborne instrument suite intended as a calibration and validation with relevance to the...

  14. Frequency-Agile Monolithic Ka-Band Filter

    Science.gov (United States)

    2012-10-18

    Watts, (v) low power consumption in the device and control circuit, (vi) fast switching speed, and (vii) temperature stability. The Phase II...nGimat 5. FABRICATION/TESTING nGimat/GT 6. OPTIMIZE FERRITE FILMS nGimat 7. FERRITE FILTERS nGimat/GT 8...Optimize Ferrite Films 60% 7. Ferrite Filters 35% 8. Prototyping 90% 9. Scale-up 80% 10. Customer Relations 70% 11. Report 100%

  15. Technology Issues for Mobile Ka-band Communications

    Science.gov (United States)

    Satorius, E.; Jedrey, T.; Davarian, F.; Divsalar, D.

    1993-01-01

    The key to success of any future telecommunications System is its ability to provide many users with a diversity of services in a cost-effective manner. An important consideration is system capacity which is requred to suport a large pool of users and their varied demands.

  16. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Science.gov (United States)

    Riihimaki, L. D.; Comstock, J. M.; Luke, E.; Thorsen, T. J.; Fu, Q.

    2017-07-01

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, ground-based vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement site are used to classify cloud phase within a deep convective cloud. The cloud cannot be fully observed by a lidar due to signal attenuation. Therefore, we developed an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka-band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid. Diffusional growth calculations show that the conditions for the Wegener-Bergeron-Findeisen process exist within one of these mixed-phase microstructures.

  17. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Riihimaki, Laura D.; Comstock, Jennifer M.; Luke, Edward; Thorsen, Tyler J.; Fu, Qiang

    2017-07-28

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement (ARM) site are used to classify cloud phase within a deep convective cloud in a shallow to deep convection transitional case. The cloud cannot be fully observed by a lidar due to signal attenuation. Thus we develop an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid, indicating complexity to how ice growth and diabatic heating occurs in the vertical structure of the cloud.

  18. Design Considerations for a Dual-Frequency Radar for Sea Spray Measurement in Hurricanes

    Science.gov (United States)

    Esteban-Fernandez, Daniel; Durden, Stephen L.; Chaubell, Julian; Cooper, Kenneth B.

    2010-01-01

    Over the last few years, researchers have determined that sea spray from breaking waves can have a large effect on the magnitude and distribution of the air-sea energy flux at hurricane-force wind speeds. Characterizing the fluxes requires estimates of the height-dependent droplet size distribution (DSD). Currently, the few available measurements have been acquired with spectrometer probes, which can provide only flight-level measurements. As such, in-situ measurement of near-surface droplet fluxes in hurricanes with these instruments is, at best, extremely challenging, if at all possible. This paper describes an airborne dual-wavelength radar profiler concept to retrieve the DSD of sea spray.

  19. Ka-Band Reliability Improvement. Part I. Volume III. Ka-Band SATCOM Set Analysis. Appendix C

    Science.gov (United States)

    1978-09-01

    SECURIT L S1 ICATION OF THIS PAGE flWbon flati Frtir-d NO ADDRESS ( IBFORE COLEING FRORMTTS 2. OW ACIESIOr REA E WO’S CAT MBER IS DISTA RII BITA T Y...wYwI 4 - # .1. z I op W 1 0 . . . ..a, I 𔃾*1 4l I c, . 4g c co n . ......... %%C C CoCs. 4 3’. 1 .I4 ." . . . ., 11 *1 Ir %, I -’ulx - I. . .,Z. 4 1. r

  20. Limitations of Radar Coordinates

    OpenAIRE

    Bini, Donato; Lusanna, Luca; Mashhoon, Bahram

    2004-01-01

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  1. RADAR PPI Scope Overlay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — RADAR PPI Scope Overlays are used to position a RADAR image over a station at the correct resolution. The archive maintains several different RADAR resolution types,...

  2. Advances in bistatic radar

    CERN Document Server

    Willis, Nick

    2007-01-01

    Advances in Bistatic Radar updates and extends bistatic and multistatic radar developments since publication of Willis' Bistatic Radar in 1991. New and recently declassified military applications are documented. Civil applications are detailed including commercial and scientific systems. Leading radar engineers provide expertise to each of these applications. Advances in Bistatic Radar consists of two major sections: Bistatic/Multistatic Radar Systems and Bistatic Clutter and Signal Processing. Starting with a history update, the first section documents the early and now declassified military

  3. Optoelectronic Properties of Dual-wavelength InGaN/GaN Multi-quantum Well Light-emitting Diodes%双波长InGaN/GaN多量子阱发光二极管的光电特性

    Institute of Scientific and Technical Information of China (English)

    陈献文; 吴乾; 李述体; 郑树文; 何苗; 范广涵; 章勇

    2011-01-01

    In order to realize preferable white light-emitting diodes with high color rendering index and optimized luminous efficiency, white InGaN/GaN multi-quantum-well dual-wavelength light-emitting diodes (LEDs) were grown on (0001)-oriented sapphire substrates by metal-organic chemical vapor deposition (MOCVD). Photoluminescence and electroluminescence properties of dual-wavelength LEDs with different I(.n) content were also studied. The experimental results indicated that In component plays a critical role on stability for electroluminescence spectrum and luminous efficiency ofthe dual-wavelength LED structures. In addition, YAG: Ce phosphor-converted white light emission with high color rendering index was achieved using dual-blue emitting active regions.%为了实现高显色指数和流明效率的白光发光二极管,在(0001)蓝宝石衬底上利用金属有机化学气相沉积系统,生长了双波长发射的InGaN/GaN多量子阱发光二极管结构.通过对不同In组分含量的双波长发射发光二极管结构的光致发光和电致发光性能进行分析,结果表明In组分含量对双波长发射发光二极管的光致发光谱的稳定性及发光效率有重要影响.此外,用双蓝光发射的芯片来激发YAG:Ce荧光粉实现了高显色指数白光发射.

  4. An Assessment of Wind Plant Complex Flows Using Advanced Doppler Radar Measurements

    Science.gov (United States)

    Gunter, W. S.; Schroeder, J.; Hirth, B.; Duncan, J.; Guynes, J.

    2015-12-01

    As installed wind energy capacity continues to steadily increase, the need for comprehensive measurements of wind plant complex flows to further reduce the cost of wind energy has been well advertised by the industry as a whole. Such measurements serve diverse perspectives including resource assessment, turbine inflow and power curve validation, wake and wind plant layout model verification, operations and maintenance, and the development of future advanced wind plant control schemes. While various measurement devices have been matured for wind energy applications (e.g. meteorological towers, LIDAR, SODAR), this presentation will focus on the use of advanced Doppler radar systems to observe the complex wind flows within and surrounding wind plants. Advanced Doppler radars can provide the combined advantage of a large analysis footprint (tens of square kilometers) with rapid data analysis updates (a few seconds to one minute) using both single- and dual-Doppler data collection methods. This presentation demonstrates the utility of measurements collected by the Texas Tech University Ka-band (TTUKa) radars to identify complex wind flows occurring within and nearby operational wind plants, and provide reliable forecasts of wind speeds and directions at given locations (i.e. turbine or instrumented tower sites) 45+ seconds in advance. Radar-derived wind maps reveal commonly observed features such as turbine wakes and turbine-to-turbine interaction, high momentum wind speed channels between turbine wakes, turbine array edge effects, transient boundary layer flow structures (such as wind streaks, frontal boundaries, etc.), and the impact of local terrain. Operational turbine or instrumented tower data are merged with the radar analysis to link the observed complex flow features to turbine and wind plant performance.

  5. On the Use of Radar Depolarization Ratios for Estimating Shapes of Ice Hydrometeors in Winter Clouds.

    Science.gov (United States)

    Matrosov, Sergey Y.; Reinking, Roger F.; Kropfli, Robert A.; Martner, Brooks E.; Bartram, B. W.

    2001-03-01

    An approach is suggested to relate measurements of radar depolarization ratios and aspect ratios of predominant hydrometeors in nonprecipitating and weakly precipitating layers of winter clouds. The trends of elevation angle dependencies of depolarization ratios are first used to distinguish between columnar-type and plate-type particles. For the established particle type, values of depolarization ratios observed at certain elevation angles, for which the influence of particle orientation is minimal, are then used to estimate aspect ratios when information on particle effective bulk density is assumed or inferred from other measurements. The use of different polarizations, including circular, slant-45° linear, and two elliptical polarizations, is discussed. These two elliptical polarizations are quasi-circular and quasi-linear slant-45° linear, and both are currently achievable with the National Oceanic and Atmospheric Administration Environmental Technology Laboratory's Ka-band radar. In comparison with the true circular and slant-45° linear polarizations, the discussed elliptical polarizations provide a stronger signal in the `weak' radar receiver channel; however, it is at the expense of diminished dynamic range of depolarization ratio variations. For depolarization measurements at the radar elevation angles that do not show much sensitivity to particle orientations, the available quasi-circular polarization provides a better depolarization contrast between nonspherical and spherical particles than does the available quasi-linear slant-45°polarization. The use of the proposed approach is illustrated with the experimental data collected during a recent field experiment. It is shown that it allows successful differentiation among pristine planar crystals, rimed planar crystals, long columns, blocky columns, and graupel. When a reasonable assumption about particle bulk density is made, quantitative estimates of particle aspect ratios from radar depolarization

  6. 双波长单光栅纳米测量中激光器性能非理想的影响%Effect of non-ideal performance of lasers in dual-wavelength single-grating nanometer measurement

    Institute of Scientific and Technical Information of China (English)

    王国超; 颜树华; 周卫红; 牛正一; 谢学东

    2011-01-01

    Principles of the dual-wavelength single grating nanometer displacement measurement system were presented, and its characteristics of long range, high precision and good stability were introduced. As a result of the nano-level high-precision displacement measurement, the errors caused by all sorts of adverse factors must be taken into account. The errors due to non-ideal performance of the dual-frequency laser were mainly discussed and analyzed, including linear errors caused by wavelength instability and non-linear errors caused by elliptic polarization of the laser. On the basis of theoretical modeling, the corresponding error formulas were derived as well. The simulation result shows that the limit value of linear errors caused by wavelength instability is 2 nm, and the limit value of nonlinear-errors caused by elliptic polarization is 1.54 nm on condition that Tx=0.85, Ty=l of the WLS and the size of the nonorthogonal angle is 1.1°. Moreover, the law of the error change was analyzed and researched by choosing different values of Tx and Ty.%阐述了双波长单光栅式大量程纳米级位移测量系统的基本原理,并对系统具有的量程大、精度高、稳定性好等特点进行了介绍.由于系统进行的是高精度纳米级的位移测量,必须考虑各种不利因素造成的误差影响,主要分析讨论了双频激光器性能非理想所造成的误差,包括波长不稳定造成的线性误差及椭圆极化偏振所造成的非线性误差.并在理论建模的基础上,导出了相应的误差表达式.最后通过仿真计算,指出波长不稳定造成的线性误差的极限值为2 nm,在非正交角为1.1°,渥拉斯顿棱镜的透过率Tx、Ty分别为0.85、1时,椭圆极化偏振所造成的非线性误差极值达到1.54nm,并选取不同的非正交角及Tx、Ty对误差变化规律进行了研究分析.

  7. Radar-to-Radar Interference Suppression for Distributed Radar Sensor Networks

    OpenAIRE

    Wen-Qin Wang; Huaizong Shao

    2014-01-01

    Radar sensor networks, including bi- and multi-static radars, provide several operational advantages, like reduced vulnerability, good system flexibility and an increased radar cross-section. However, radar-to-radar interference suppression is a major problem in distributed radar sensor networks. In this paper, we present a cross-matched filtering-based radar-to-radar interference suppression algorithm. This algorithm first uses an iterative filtering algorithm to suppress the radar-to-radar ...

  8. An attempt to calibrate the UHF strato-tropospheric radar at Arecibo using NexRad radar and disdrometer data

    Directory of Open Access Journals (Sweden)

    P. Kafando

    2004-12-01

    Full Text Available The goal of this paper is to present a methodology to calibrate the reflectivity of the UHF Strato-Tropospheric (ST radar located at NAIC in Puerto Rico. The UHF lower relevant altitude is at 5.9km, the melting layer being at around 4.8km. The data used for the calibration came from the observations of clouds, carried out with Strato-Tropospheric dual-wavelength (UHF and VHF radars and a disdrometer; those instruments being located on the NAIC site in Arecibo, Puerto Rico. The National Weather Service operates other instruments like the radiosondes and the NexRad Radar in other sites.

    The proposed method proceeds in two steps. The first consists of the comparison between the NexRad reflectivity and the reflectivity computed from the drop size distributions measured by the disdrometer for one day with a noticeable rainfall rate. In spite of the distance of both instruments, the agreement between the reflectivities of both instruments is enough good to be used as a reference for the UHF ST radar. The errors relative at each data set is found to be 2.75dB for the disdrometer and 4dB for the NexRad radar, following the approach of Hocking et al. (2001. The inadequacy between the two sampled volume is an important contribution in the errors.

    The second step consists of the comparison between the NexRad radar reflectivity and the UHF non-calibrated reflectivity at the 4 altitudes of common observations during one event on 15 October 1998. Similar features are observed and a coefficient is deduced. An offset around 4.7dB is observed and the correlation factor lies between 0.628 and 0.730. According to the errors of the data sets, the precision on the calibration is of the order of 2dB. This method works only when there are precipitation hydrometeors above the NAIC site. However, the result of the calibration could be applied to other data obtained during the campaign, the only

  9. Adaptive radar resource management

    CERN Document Server

    Moo, Peter

    2015-01-01

    Radar Resource Management (RRM) is vital for optimizing the performance of modern phased array radars, which are the primary sensor for aircraft, ships, and land platforms. Adaptive Radar Resource Management gives an introduction to radar resource management (RRM), presenting a clear overview of different approaches and techniques, making it very suitable for radar practitioners and researchers in industry and universities. Coverage includes: RRM's role in optimizing the performance of modern phased array radars The advantages of adaptivity in implementing RRMThe role that modelling and

  10. Radar and ARPA manual

    CERN Document Server

    Bole, A G

    2013-01-01

    Radar and ARPA Manual focuses on the theoretical and practical aspects of electronic navigation. The manual first discusses basic radar principles, including principles of range and bearing measurements and picture orientation and presentation. The text then looks at the operational principles of radar systems. Function of units; aerial, receiver, and display principles; transmitter principles; and sitting of units on board ships are discussed. The book also describes target detection, Automatic Radar Plotting Aids (ARPA), and operational controls of radar systems, and then discusses radar plo

  11. 基于多模光纤偏振烧孔效应的双波长掺铒光纤激光器%Dual-wavelength Er-doped fiber laser based on polarization hole burning of multi-mode fiber

    Institute of Scientific and Technical Information of China (English)

    董凤娟; 杨秀峰; 童峥嵘; 曹晔

    2011-01-01

    A dual-wavelength Er-doped fiber laser based on polarization hole burning (PHB) of multi-mode fiber is proposed The structure of single mode fiber (SMF)-multi-mode fiber (MMF)-SMF makes reflection modes in different polarization directions of MMF split. Thus,dual-wavelength laser output is realized through PHB. Moreover, the wavelength spacing can alter through changing the length of MMF. In this paper,the output characteristics are compared when a MMF with length of 1. 6 m and 3 m are introduced, respectively. The results indicate that the output wavelength spacing becomes smaller but the output power increases when the length of MMF increases. Finally,a stable dual-wavelength with 55 dB extinction ratio,53 dB side mode suppression ratio and -2 dBm output power is realized through the PHB and the influence of polarization-dependent isolator (PDI) and polarization controller(PC).%基于多模光纤(MMF)引入的偏振烧孔(PHB)效应,研制了一种环形双波长掺铒光纤(EDF)激光器.单模光纤(SMF)-MMF-SMF组成的结构使MMF不同偏振方向的反射模在波长上分开,利用PHB效应实现双波长的输出,输出波长间隔可通过改变MMF的长度改变.实验对比了1.6 m和3.0 m长的MMF输出波谱特性,结果表明,通过增加MMF的长度,不但可以使输出波长的波长间隔变小,而且输出功率也会有一定的提高.本文研制的激光器,通过PHB效应以及偏振相关隔离器(PDI)和偏振控制器(PC)的影响,在常温下实现了消光比为55 dB、边模抑制比为53 dB以及输出功率为-2 dBm的两个连续波长的稳定输出.

  12. Determination of Palladium Content in Spent Catalyst for Hydrogen Peroxide Production by Dual-Wavelength Equivalent Absorbance Spectrophotometry%双波长等吸收法测定双氧水用废催化剂中钯的含量

    Institute of Scientific and Technical Information of China (English)

    韩守礼; 赵雨; 郭俊梅; 谭文进; 贺小塘; 李琨; 李勇; 刘文; 吴喜龙; 王欢

    2015-01-01

    建立了双波长等吸收法测定双悦水用废催化剂中钯含量的方法,优化了测定条件,与GB/T 23220-2009分析方法进行了对照。结果表明,在恒定的条件下,双波长法等吸收法较单波长法测定钯的恒择性好;测定悪品中251.6~5563.9 g/t的钯,相对标准偏差(RSD,n=22)为0.387%∼0.795%,允恀差(3S)为6∼78 g/t,相对允恀差为1.2%∼2.3%;悪品加标准回收率99.35%~100.55%。测定结果与GB/T 23220-2009分析方法的结果吻合。%A method for determination of palladium content in spent catalysts for hydrogen peroxide production by dual-wavelength equivalent absorbance spectrophotometry was established. Conditions for determination of palladium were systemic investigated and optimized. Effect of errors coming from coexisting ions on determination of palladium by dual-wavelength equivalent absorbance spectrophoto-metry and odd-wavelength spectrophotometry was compared, and results determined by the proposed method were comparied with GB/T 23220-2009. Results indicated that the selectivity of dual-wavelength equivalent absorbance spectro-photometry is better than that of odd-wavelength spectrophotometry under chosen conditions. Palladium contents of 251.6~5563.9 g/t in hydrogen peroxide using spent catalysts were measured, and the relative standard deviation (RSD, n=22) was 0.387%∼0.795%, permission deviation (3S) was 6∼78 g/t, and relative permission deviation was 1.2%∼2.3%, respectively. Recoveries of standard addition were 99.35%~100.55%. Analytical results of the proposed method were in reasonable agreement with those of GB/T 23220-2009.

  13. Comprehensive Radar Observations of Clouds and Precipitation over the Tibetan Plateau and Preliminary Analysis of Cloud Properties

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Intensive fi eld experiment is an important approach to obtain microphysical information about clouds and precipitation. From 1 July to 31 August 2014, the third Tibetan Plateau Atmospheric Science Experiment was carried out and comprehensive measurements of water vapor, clouds, and precipitation were conducted at Naqu. The most advanced radars in China, such as Ka-band millimeter-wave cloud radar, Ku-band micro-rain radar, C-band continuous-wave radar and lidar, and microwave radiometer and disdrometer were deployed to observe high spatial-temporal vertical structures of clouds and precipitation. The C-band dual-linear polarization radar was coordinated with the China new generation weather radar to constitute a dual-Doppler radar system for the measurements of three-dimensional wind fi elds within convective precipitations and the structure and evolution of hydrometeors related to precipitation process. Based on the radar measurements in this experiment, the diurnal variations of several important cloud properties were analyzed, including cloud top and base, cloud depth, cloud cover, number of cloud layers, and their vertical structures during summertime over Naqu. The features of refl ectivity, velocity, and depolarization ratio for diff erent types of clouds observed by cloud radar are discussed. The results indicate that the cloud properties were successfully measured by using various radars in this fi eld experiment. During the summertime over Naqu, most of the clouds were located above 6 km and below 4 km above ground level. Statistical analysis shows that total amounts of clouds, the top of high-level clouds, and cloud depth, all demonstrated a distinct diurnal variation. Few clouds formed at 1000 LST (local standard time), whereas large amounts of clouds formed at 2000 LST. Newly formed cumulus and stratus clouds were often found at 3-km height, where there existed signifi cant updrafts. Deep convection reached up to 16.5 km (21 km above the mean sea level

  14. Principles of modern radar systems

    CERN Document Server

    Carpentier, Michel H

    1988-01-01

    Introduction to random functions ; signal and noise : the ideal receiver ; performance of radar systems equipped with ideal receivers ; analysis of the operating principles of some types of radar ; behavior of real targets, fluctuation of targets ; angle measurement using radar ; data processing of radar information, radar coverage ; applications to electronic scanning antennas to radar ; introduction to Hilbert spaces.

  15. Passive MIMO Radar Detection

    Science.gov (United States)

    2013-09-01

    cumulative distribution function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 CORA COvert RAdar...PaRaDe), developed by the Insti- tute of Electronic Systems at the Warsaw University of Technology [59, 60]; COvert RAdar ( CORA ), developed by the German

  16. Weather Radar Impact Zones

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent an inventory of the national impacts of wind turbine interference with NEXRAD radar stations. This inventory was developed by the NOAA Radar...

  17. Digital LPI Radar Detector

    OpenAIRE

    Ong, Peng Ghee; Teng, Haw Kiad

    2001-01-01

    Approved for public release; distribution is unlimited The function of a Low Probability ofIntercept (LPI) radar is to prevent its interception by an Electronic Support (ES) receiver. This objective is generally achieved through the use of a radar waveform that is mismatched to those waveforms for which an ES receiver is tuned. This allows the radar to achieve a processing gain, with respect to the ES receiver, that is equal to the time-bandwidth product ofthe radar waveform. This...

  18. Network radar countermeasure systems integrating radar and radar countermeasures

    CERN Document Server

    Jiang, Qiuxi

    2016-01-01

    This is the very first book to present the network radar countermeasure system. It explains in detail the systematic concept of combining radar and radar countermeasures from the perspective of the information acquisition of target location, the optimization of the reconnaissance and detection, the integrated attack of the signals and facilities, and technological and legal developments concerning the networked system. It achieves the integration of the initiative and passivity, detection and jamming. The book explains how the system locates targets, completes target identification, tracks targets and compiles the data.

  19. Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars

    Science.gov (United States)

    Mishra, Kumar Vijay

    The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi

  20. Deep Stochastic Radar Models

    OpenAIRE

    Wheeler, Tim Allan; Holder, Martin; Winner, Hermann; Kochenderfer, Mykel

    2017-01-01

    Accurate simulation and validation of advanced driver assistance systems requires accurate sensor models. Modeling automotive radar is complicated by effects such as multipath reflections, interference, reflective surfaces, discrete cells, and attenuation. Detailed radar simulations based on physical principles exist but are computationally intractable for realistic automotive scenes. This paper describes a methodology for the construction of stochastic automotive radar models based on deep l...

  1. Radar: Human Safety Net

    Science.gov (United States)

    Ritz, John M.

    2016-01-01

    Radar is a technology that can be used to detect distant objects not visible to the human eye. A predecessor of radar, called the telemobiloscope, was first used to detect ships in the fog in 1904 off the German coast. Many scientists have worked on the development and refinement of radar (Hertz with electromagnetic waves; Popov with determining…

  2. Radar and wind turbines; Radar en windturbines

    Energy Technology Data Exchange (ETDEWEB)

    Van Doorn, H.

    2010-03-15

    In the last years the developments of wind parks were hampered because of their possible effect on the radar for observation of air traffic. Work is currently being done on a new assessment model for wind turbines under the auspices of the steering group National Security for the military radar systems. Air traffic control Netherlands (LVNL) will look at the options for civil radars to join in. [Dutch] In de afgelopen jaren zijn windparkontwikkelingen onder meer belemmerd vanwege mogelijke effecten op radar voor de waarneming van luchtverkeer. Onder auspicien van de stuurgroep Nationale Veiligheid voor de militaire radarsystemen op land wordt gewerkt aan een nieuw beoordelingsmodel voor windturbines. De Luchtverkeersleiding Nederland (LVNL) zal bezien in hoeverre de civiele radars hierbij kunnen aansluiten.

  3. Dual wavelength spectrophotometry and K-ratio spectrophotometry in determining compatible stability of cefepime with metronidazole%紫外双波长、系数倍率法测定头孢吡肟与甲硝唑配伍的稳定性

    Institute of Scientific and Technical Information of China (English)

    罗宇芬; 叶萍; 赵珊

    2001-01-01

    目的:考察头孢吡肟与0.5%甲硝唑配伍的稳定性。方法:用紫外双波长、系数倍率法分别测定头孢吡肟与甲硝唑的含量。结果:在0,1,2,4,6 h内,2药合用的含量、pH及外观基本不变。该方法的平均回收率头孢吡肟为(100.9±0.4) %(n=5),甲硝唑为(99.8±0.6) %(n=5)。结论:2种药物配伍6 h内基本稳定。用双波长、系数倍率法分别测定其稳定性,方法简便、准确、实用性广。%AIM: To study the compatible stability of cefepime with 0.5% metronidazole injection. METHODS: Dual wavelength spectrophotometry and K-ratio spectrophotometry were described for the determination of cefepime with metronidazole injection during 6 h.  RESULTS: There was no evident variation in content during 6 h at room temperature. The average recovery rates of cefepime and metronidazole were (100.9±0.4)% and (99.8±0.6)% (n=5). CONCLUSION: The compatiblity of cefepime with metronidazole injection is stable. The method of using dual wavelength spectrophotometry and K-ratio spectrophotometry to determine the compatible stability of cefepime with metronidazole is simple, accurate and usable.

  4. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  5. Understanding radar systems

    CERN Document Server

    Kingsley, Simon

    1999-01-01

    What is radar? What systems are currently in use? How do they work? This book provides engineers and scientists with answers to these critical questions, focusing on actual radar systems in use today. It is a perfect resource for those just entering the field, or as a quick refresher for experienced practitioners. The book leads readers through the specialized language and calculations that comprise the complex world of radar engineering as seen in dozens of state-of-the-art radar systems. An easy to read, wide ranging guide to the world of modern radar systems.

  6. Multidimensional radar picture

    Science.gov (United States)

    Waz, Mariusz

    2010-05-01

    In marine navigation systems, the three-dimensional (3D) visualization is often and often used. Echosonders and sonars working in hydroacustic systems can present pictures in three dimensions. Currently, vector maps also offer 3D presentation. This presentation is used in aviation and underwater navigation. In the nearest future three-dimensional presentation may be obligatory presentation in displays of navigation systems. A part of these systems work with radar and communicates with it transmitting data in a digital form. 3D presentation of radar picture require a new technology to develop. In the first step it is necessary to compile digital form of radar signal. The modern navigation radar do not present data in three-dimensional form. Progress in technology of digital signal processing make it possible to create multidimensional radar pictures. For instance, the RSC (Radar Scan Converter) - digital radar picture recording and transforming tool can be used to create new picture online. Using RSC and techniques of modern computer graphics multidimensional radar pictures can be generated. The radar pictures mentioned should be readable for ECDIS. The paper presents a method for generating multidimensional radar picture from original signal coming from radar receiver.

  7. High Power mm-Wave Transmitter System for Radar or Telecommunications

    Science.gov (United States)

    Stride, S. L.; McMaster, R. L.; Pogorzelski, R. J.

    2003-01-01

    Future NASA deep space missions able to provide tens of kilo-watts of spacecraft DC power, make it feasible to employ high power RF telecommunications systems. Traditional flight systems (e.g., Cassini), constrained by limited DC power, used a single high-gain 4m Cassegrain reflector fed by a single lower power (20W) transmitter. Increased available DC power means that high power (1000 W) transmitters can be used. Rather than continue building traditional single-transmitter systems it now becomes feasible to engineer and build multi-element active arrays that can illuminate a dish. Illuminating a 2m dish with a spherical wavefront from an offset 1kW active array can provide sufficient ERP (Effective Radiated Power) when compared to a larger Cassegrain dish. Such a system has the advantage of lower mass, lower volume, improved reliability, less stringent pointing requirements, lower cost and risk. We propose to design and build a prototype Ka-band transmit antenna with an active sub-array using 125W TWTAs. The system could be applied to a telecommunications downlink or radar transmitter used for missions such as JIMO.

  8. Development of a polarimetric radar based hydrometeor classification algorithm for winter precipitation

    Science.gov (United States)

    Thompson, Elizabeth Jennifer

    The nation-wide WSR-88D radar network is currently being upgraded for dual-polarized technology. While many convective, warm-season fuzzy-logic hydrometeor classification algorithms based on this new suite of radar variables and temperature have been refined, less progress has been made thus far in developing hydrometeor classification algorithms for winter precipitation. Unlike previous studies, the focus of this work is to exploit the discriminatory power of polarimetric variables to distinguish the most common precipitation types found in winter storms without the use of temperature as an additional variable. For the first time, detailed electromagnetic scattering of plates, dendrites, dry aggregated snowflakes, rain, freezing rain, and sleet are conducted at X-, C-, and S-band wavelengths. These physics-based results are used to determine the characteristic radar variable ranges associated with each precipitation type. A variable weighting system was also implemented in the algorithm's decision process to capitalize on the strengths of specific dual-polarimetric variables to discriminate between certain classes of hydrometeors, such as wet snow to indicate the melting layer. This algorithm was tested on observations during three different winter storms in Colorado and Oklahoma with the dual-wavelength X- and S-band CSU-CHILL, C-band OU-PRIME, and X-band CASA IP1 polarimetric radars. The algorithm showed success at all three frequencies, but was slightly more reliable at X-band because of the algorithm's strong dependence on KDP. While plates were rarely distinguished from dendrites, the latter were satisfactorily differentiated from dry aggregated snowflakes and wet snow. Sleet and freezing rain could not be distinguished from rain or light rain based on polarimetric variables alone. However, high-resolution radar observations illustrated the refreezing process of raindrops into ice pellets, which has been documented before but not yet explained. Persistent

  9. Phased-array radar design application of radar fundamentals

    CERN Document Server

    Jeffrey, Thomas

    2009-01-01

    Phased-Array Radar Design is a text-reference designed for electrical engineering graduate students in colleges and universities as well as for corporate in-house training programs for radar design engineers, especially systems engineers and analysts who would like to gain hands-on, practical knowledge and skills in radar design fundamentals, advanced radar concepts, trade-offs for radar design and radar performance analysis.

  10. Radar Signature Calculation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: The calculation, analysis, and visualization of the spatially extended radar signatures of complex objects such as ships in a sea multipath environment and...

  11. Doppler radar physiological sensing

    CERN Document Server

    Lubecke, Victor M; Droitcour, Amy D; Park, Byung-Kwon; Singh, Aditya

    2016-01-01

    Presents a comprehensive description of the theory and practical implementation of Doppler radar-based physiological monitoring. This book includes an overview of current physiological monitoring techniques and explains the fundamental technology used in remote non-contact monitoring methods. Basic radio wave propagation and radar principles are introduced along with the fundamentals of physiological motion and measurement. Specific design and implementation considerations for physiological monitoring radar systems are then discussed in detail. The authors address current research and commercial development of Doppler radar based physiological monitoring for healthcare and other applications.

  12. Combined radar and telemetry system

    Energy Technology Data Exchange (ETDEWEB)

    Rodenbeck, Christopher T.; Young, Derek; Chou, Tina; Hsieh, Lung-Hwa; Conover, Kurt; Heintzleman, Richard

    2017-08-01

    A combined radar and telemetry system is described. The combined radar and telemetry system includes a processing unit that executes instructions, where the instructions define a radar waveform and a telemetry waveform. The processor outputs a digital baseband signal based upon the instructions, where the digital baseband signal is based upon the radar waveform and the telemetry waveform. A radar and telemetry circuit transmits, simultaneously, a radar signal and telemetry signal based upon the digital baseband signal.

  13. 选择性P型量子阱垒层掺杂在双波长发光二极管光谱调控中的作用%Investigation of spectral regulation in dual wavelength light-emitting diodes by using the selective p-doped barrier*

    Institute of Scientific and Technical Information of China (English)

    陈峻; 范广涵; 张运炎

    2012-01-01

    The electrical and the optical characteristics of dual-wavelength light-emitting diode (LED) with the newly designed selective p-doped barriers are investigated numerically. The simulation results show that the selective p-doped barriers can improve the distribution equilibria of electron and hole concentrations in each quantum well (QW). The radiative recombination rate of QW is enhanced remarkably when specific number of p-doped barriers is adopted, and the electron leakage current is suppressed obviously with this new design. Therefore, the internal quantum efficiency is improved and the trend of efficiency drooping with the increase of current injection is also alleviated. Moreover, the curve peaks of the spectrum become quite uniform when the specific number of vertically-stacked QWs is adopted, and the spectral regulation of the dual-wavelength LED is more effective%采用软件理论分析的方法对选择性P型掺杂量子阱垒层在InGaN双波长发光二极管(LED)中的光谱调控作用进行模拟分析.分析结果表明,选择性P型掺杂对量子阱中电子和空穴浓度分布的均衡性起到一定的调控作用,在适当选择P型掺杂量子阱垒层层数的条件下,能够改善量子阱中载流子的辐射复合速率,降低溢出电子浓度,从而有效提高芯片内量子效率,并减缓内量子效率随驱动电流增大而快速下降的趋势.随着活性层量子阱增加到特定数量,选择性P型掺杂的调控效果更加明显,LED芯片的双波长发光峰强度达到基本均衡.

  14. Recent updates of a GPM Radar Simulator using CRM data with Bulk Microphysics

    Science.gov (United States)

    Kim, H.; Meneghini, R.; Jones, J.; Liao, L.

    2012-12-01

    The goal of Global Precipitation Measurement (GPM) mission is to provide more accurate global precipitation information within ±65° latitude every 2~4 hour. GPM core satellite which carries the Dual-frequency Precipitation Radar (DPR) operating at Ku- and Ka-band will be launched in February, 2014. A number of radar precipitation retrieval algorithms are being developed for Level-2 radar processing. To support radar algorithm developers who need test data to evaluate the performance of their algorithm, a GPM radar simulator has been developed to generate synthetic Level-1 products which include the most important component, the received echo power, as well as radar parameters required for Level-2 algorithm processing. The GPM radar simulator consists of two modules. One is the DPR scanning geometry module that specifies the characteristics of the DPR sensor and emulates the scan and antenna geometry of the DPR. The other module is the forward calculation module that takes as input the prognostic variables (mixing ratio of hydrometeors) of high resolution cloud-resolving model data, using a one moment bulk microphysics scheme, and computes radar scattering parameters consistent with the microphysical assumptions of the hydrometeors. The forward calculation module also includes a surface scattering model to compute the radar return power from the illuminated surface area by means of a model for the normalized radar cross section (σ0 or NRCS), given as a function of incidence angle and surface type (land/ocean). The simulation of the surface return power plays an important role for one of primary DPR retrieval algorithms, the Surface Reference Technique (SRT), that estimates path-integrated attenuation (PIA) from the surface returns under rain and no-rain condition. Recently, we have completed an update of the surface scattering model for land. Like the NRCS over ocean, the NRCS over land is modeled by taking realizations from a jointly Gaussian random variable

  15. Radar illusion via metamaterials

    Science.gov (United States)

    Jiang, Wei Xiang; Cui, Tie Jun

    2011-02-01

    An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

  16. Java Radar Analysis Tool

    Science.gov (United States)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  17. Determination of radar MTF

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  18. Aspects of Radar Polarimetry

    OpenAIRE

    Lüneburg, Ernst

    2002-01-01

    This contribution is a tutorial introduction to the phenomenological theory of radar polarimetry for the coherent scatter case emphasizing monostatic backscattering and forward scattering (transmission). Characteristic similarities and differences between radar polarimetry and optical polarimetry and the role of linear and antilinear operators (time-reversal) are pointed out and typical polarimetric invariants are identified.

  19. The Cloud Radar System

    Science.gov (United States)

    Racette, Paul; Heymsfield, Gerald; Li, Lihua; Tian, Lin; Zenker, Ed

    2003-01-01

    Improvement in our understanding of the radiative impact of clouds on the climate system requires a comprehensive view of clouds including their physical dimensions, dynamical generation processes, and detailed microphysical properties. To this end, millimeter vave radar is a powerful tool by which clouds can be remotely sensed. The NASA Goddard Space Flight Center has developed the Cloud Radar System (CRS). CRS is a highly sensitive 94 GHz (W-band) pulsed-Doppler polarimetric radar that is designed to fly on board the NASA high-altitude ER-2 aircraft. The instrument is currently the only millimeter wave radar capable of cloud and precipitation measurements from above most all clouds. Because it operates from high-altitude, the CRS provides a unique measurement perspective for cirrus cloud studies. The CRS emulates a satellite view of clouds and precipitation systems thus providing valuable measurements for the implementation and algorithm validation for the upcoming NASA CloudSat mission that is designed to measure ice cloud distributions on the global scale using a spaceborne 94 GHz radar. This paper describes the CRS instrument and preliminary data from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE). The radar design is discussed. Characteristics of the radar are given. A block diagram illustrating functional components of the radar is shown. The performance of the CRS during the CRYSTAL-FACE campaign is discussed.

  20. Dual ?frequency Cloud Radar (DCR) System for EV-3 Missions and Beyond Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The effort will involve a mechanical and thermal study for installation of CRS into the Global Hawk, RF design for integrating the HIWRAP Ka-band transceiver with...

  1. Micropower impulse radar imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  2. Principles of modern radar radar applications

    CERN Document Server

    Scheer, James A

    2013-01-01

    Principles of Modern Radar: Radar Applications is the third of the three-volume seriesof what was originally designed to be accomplished in one volume. As the final volumeof the set, it finishes the original vision of a complete yet bounded reference for radartechnology. This volume describes fifteen different system applications or class ofapplications in more detail than can be found in Volumes I or II.As different as the applications described, there is a difference in how these topicsare treated by the authors. Whereas in Volumes I and II there is strict adherence tochapter format and leve

  3. Monolithic microwave integrated circuits for sensors, radar, and communications systems; Proceedings of the Meeting, Orlando, FL, Apr. 2-4, 1991

    Science.gov (United States)

    Leonard, Regis F.; Bhasin, Kul B.

    Consideration is given to MMICs for airborne phased arrays, monolithic GaAs integrated circuit millimeter wave imaging sensors, accurate design of multiport low-noise MMICs up to 20 GHz, an ultralinear low-noise amplifier technology for space communications, variable-gain MMIC module for space applications, a high-efficiency dual-band power amplifier for radar applications, a high-density circuit approach for low-cost MMIC circuits, coplanar SIMMWIC circuits, recent advances in monolithic phased arrays, and system-level integrated circuit development for phased-array antenna applications. Consideration is also given to performance enhancement in future communications satellites with MMIC technology insertion, application of Ka-band MMIC technology for an Orbiter/ACTS communications experiment, a space-based millimeter wave debris tracking radar, low-noise high-yield octave-band feedback amplifiers to 20 GHz, quasi-optical MESFET VCOs, and a high-dynamic-range mixer using novel balun structure. (For individual items see A93-25777 to A93-25814)

  4. Air-Sea Spray Airborne Radar Profiler Characterizes Energy Fluxes in Hurricanes

    Science.gov (United States)

    Durden, Stephen L.; Esteban-Fermandez, D.

    2010-01-01

    A report discusses ASAP (Air-sea Spray Airborne Profiler), a dual-wavelength radar profiler that provides measurement information about the droplet size distribution (DSD) of sea-spray, which can be used to estimate heat and moisture fluxes for hurricane research. Researchers have recently determined that sea spray can have a large effect on the magnitude and distribution of the air-sea energy flux at hurricane -force wind speeds. To obtain information about the DSD, two parameters of the DSD are required; for example, overall DSD amplitude and DSD mean diameter. This requires two measurements. Two frequencies are used, with a large enough separation that the differential frequency provides size information. One frequency is 94 GHz; the other is 220 GHz. These correspond to the Rayleigh and Mie regions. Above a surface wind speed of 10 m/ s, production of sea spray grows exponentially. Both the number of large droplets and the altitude they reach are a function of the surface wind speed.

  5. Radar cross section

    CERN Document Server

    Knott, Gene; Tuley, Michael

    2004-01-01

    This is the second edition of the first and foremost book on this subject for self-study, training, and course work. Radar cross section (RCS) is a comparison of two radar signal strengths. One is the strength of the radar beam sweeping over a target, the other is the strength of the reflected echo sensed by the receiver. This book shows how the RCS ?gauge? can be predicted for theoretical objects and how it can be measured for real targets. Predicting RCS is not easy, even for simple objects like spheres or cylinders, but this book explains the two ?exact? forms of theory so well that even a

  6. Radar and electronic navigation

    CERN Document Server

    Sonnenberg, G J

    2013-01-01

    Radar and Electronic Navigation, Sixth Edition discusses radar in marine navigation, underwater navigational aids, direction finding, the Decca navigator system, and the Omega system. The book also describes the Loran system for position fixing, the navy navigation satellite system, and the global positioning system (GPS). It reviews the principles, operation, presentations, specifications, and uses of radar. It also describes GPS, a real time position-fixing system in three dimensions (longitude, latitude, altitude), plus velocity information with Universal Time Coordinated (UTC). It is accur

  7. HIWRAP Radar Development for High-Altitude Operation on the NASA Global Hawk and ER-2

    Science.gov (United States)

    Li, Lihua; Heymsfield, Gerlad; Careswell, James; Schaubert, Dan; Creticos, Justin

    2011-01-01

    The NASA High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) is a solid-state transmitter-based, dual-frequency (Ka- and Ku-band), dual-beam (30 degree and 40 degree incidence angle), conical scan Doppler radar system, designed for operation on the NASA high-altitude (20 km) aircrafts, such as the Global Hawk Unmanned Aerial System (UAS). Supported by the NASA Instrument Incubator Program (IIP), HIWRAP was developed to provide high spatial and temporal resolution 3D wind and reflectivity data for the research of tropical cyclone and severe storms. With the simultaneous measurements at both Ku- and Ka-band two different incidence angles, HIWRAP is capable of imaging Doppler winds and volume backscattering from clouds and precipitation associated with tropical storms. In addition, HIWRAP is able to obtain ocean surface backscatter measurements for surface wind retrieval using an approach similar to QuikScat. There are three key technology advances for HIWRAP. Firstly, a compact dual-frequency, dual-beam conical scan antenna system was designed to fit the tight size and weight constraints of the aircraft platform. Secondly, The use of solid state transmitters along with a novel transmit waveform and pulse compression scheme has resulted in a system with improved performance to size, weight, and power ratios compared to typical tube based Doppler radars currently in use for clouds and precipitation measurements. Tube based radars require high voltage power supply and pressurization of the transmitter and radar front end that complicates system design and implementation. Solid state technology also significantly improves system reliability. Finally, HIWRAP technology advances also include the development of a high-speed digital receiver and processor to handle the complex receiving pulse sequences and high data rates resulting from multi receiver channels and conical scanning. This paper describes HIWRAP technology development for dual-frequency operation at

  8. Nexrad-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    Science.gov (United States)

    Im, E.; Chandrasekar, V.; Chen, S. S.; Holland, G. J.; Kakar, R.; Lewis, W. E.; Marks, F. D.; Smith, E. A.; Tanelli, S.; Tripoli, G. J.

    2007-12-01

    The Nexrad-In-Space (NIS) is a revolutionary atmospheric radar observation concept from the geostationary orbiting platform. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS radar would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with a 12-km horizontal resolution, and a minimum detectable signal of 5 dBZ. The NIS radar achieves its superb sampling capabilities by use of a 35-m diameter, deployable antenna made from lightweight membrane material. The antenna has two transmit-receive array pairs that create a dual-beam, spiral-feed combined profile image of both reflectivity and Doppler velocity approximately every 60 minutes. This sampling time can be shortened even further by increasing the number of transmit-receive array pairs. It is generally recognized that the processes important in governing hurricane intensity and structure span a wide range of spatial and temporal scales. The environmental forcing considerations require a large domain. The vortex response to the environmental forcing ultimately involves convection on small horizontal scales in the eyewall and rainband regions. Resolving this environment-vortex-convection feedback in a numerical model requires observations on the space and time scales necessary to unambiguously define these structures within and surrounding the tropical cyclone. Because the time and space scales of these processes are small, continuous 3-dimensional independent observations of the 3-dimensional wind and precipitation structures will be needed to initialize numerical models critical for this purpose. The proposed NIS Doppler radar would be the first instrument capable of accomplishing this feat at time scales less than hours, and would create the opportunity for hurricane science to enter a new era of understanding and improved prediction. This

  9. Wind Profiling Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Clutter present in radar return signals as used for wind profiling is substantially removed by carrying out a Daubechies wavelet transformation on a time series of...

  10. Imaging Radar Polarimetry

    Science.gov (United States)

    vanZyl, J. J.; Zebker, H. A.

    1993-01-01

    In this paper, we review the state of the art in imaging radar polarimetry, examine current developments in sensor technology and implementation for recording polarimetric measurements, and describe techniques and areas of application for the new remote sensing data.

  11. Radar Landmass Simulation Computer Programming (Interim Report).

    Science.gov (United States)

    RADAR SCANNING, TERRAIN), (*NAVAL TRAINING, RADAR OPERATORS), (*FLIGHT SIMULATORS, TERRAIN AVOIDANCE), (* COMPUTER PROGRAMMING , INSTRUCTION MANUALS), PLAN POSITION INDICATORS, REAL TIME, DISPLAY SYSTEMS, RADAR IMAGES, SIMULATION

  12. Current status of the dual-frequency precipitation radar on the global precipitation measurement core spacecraft and the new version of GPM standard products

    Science.gov (United States)

    Furukawa, K.; Nio, T.; Konishi, T.; Masaki, T.; Kubota, T.; Oki, R.; Iguchi, T.

    2016-10-01

    The Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core satellite was developed by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT). The objective of the GPM mission is to observe global precipitation more frequently and accurately. The GPM core satellite is a joint product of National Aeronautics and Space Administration (NASA), JAXA and NICT. NASA developed the satellite bus and the GPM Microwave Imager (GMI), and JAXA and NICT developed the DPR. The inclination of the GPM core satellite is 65 degrees, and the nominal flight altitude is 407 km. The non-sunsynchronous circular orbit is necessary for measuring the diurnal change of rainfall. The DPR consists of two radars, which are Ku-band precipitation radar (KuPR) and Ka-band precipitation radar (KaPR). GPM core observatory was successfully launched by H2A launch vehicle on Feb. 28, 2014. DPR keeps its performances on orbit after launch. DPR products were released to the public on Sep. 2, 2014. JAXA is continuing DPR trend monitoring, calibration and validation operations to confirm that DPR keeps its function and performance on orbit. JAXA have started to provide new version (Version 4) of GPM standard products on March 3, 2016. Various improvements of the DPR algorithm were implemented in the Version 4 product. Moreover, the latent heat product based on the Spectral Latent Heating (SLH) algorithm is available since Version 4 product. Current orbital operation status of the GPM/DPR and highlights of the Version 4 product are reported.

  13. Downhole pulse radar

    Science.gov (United States)

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  14. 基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术%A technique for tunable microwave/millimeter-wave generation based on a polarization-stable dual-wavelength polarization maintaining fiber Bragg grating laser

    Institute of Scientific and Technical Information of China (English)

    裴丽; 刘观辉; 宁提纲; 高嵩; 李晶; 张义军

    2012-01-01

    首次提出了一种基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术,利用保偏光纤光栅选频产生两个偏振稳定的激光信号,采用扰偏器确保激光输出的两个正交偏振态功率的一致性,最后输入高速光电探测器产生微波/毫米波.通过对保偏光纤光栅施加不同大小的侧向应力,可以灵活调谐输出的毫米波频率.实验制作了基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生装置,通过对保偏光纤光栅施加不同的轴向拉力分别产生了20.407和22.050 GHz的微波信号.仿真产生了60 GHz的毫米波信号,并分析该毫米波在光纤无线通信下行链路的传输性能,结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端,解调后仍然得到很好的眼图,充分证明了本方案的优越传输性能.%A technique for tunable microwave/millimeter-wave generation based on a polarization-stable dual-wavelength polarization maintaining fiber Bragg grating(PMFBG) laser is proposed in which the frequency selecting of PMFBG is used to produce two polarizationstable lasing signals,the polarization scrambler is adopted to ensure the consistency of the orthogonal polarization's power,and then the beating frequency in high-speed photodetector is used to generate the microwave/millimeter-wave.Lateral strain loading on the PMFBG allows the frequency of the microwave/millimeter to be controlled.In the experiment,a scheme for tunable microwave/millimeter-wave generation based on a polarization-stable dual-wavelength PMFBG laser is produced,and the microwave signals of 20.407 GHz and 22.050 GHz are generated by different axial pulls loading on PMFBG.In the simulation,the millimeter-wave of 60 GHz is generated and transmission performance of the millimeter-wave in radio-over-fiber downlink is analyzed.The results show that the eye diagrams

  15. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  16. Delay time calculation for dual-wavelength quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hamadou, A., E-mail: abd-hamado@yahoo.fr [Département des Sciences et Techniques, Faculté des Sciences et de la Technologie, Université de Bordj Bou Arreridj 34000 (Algeria); Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Lamari, S. [Laboratoire d’étude des surfaces et interfaces des matériaux solides (LESIMS), Sétif 19000 (Algeria); Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 (Algeria); Thobel, J.-L. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR 8520, Université Lille1, Avenue Poincaré, BP 60069, 59652 Villeneuve d' Ascq Cédex (France)

    2013-11-28

    In this paper, we calculate the turn-on delay (t{sub th}) and buildup (Δt) times of a midinfrared quantum cascade laser operating simultaneously on two laser lines having a common upper level. The approach is based on the four-level rate equations model describing the variation of the electron number in the states and the photon number present within the cavity. We obtain simple analytical formulae for the turn-on delay and buildup times that determine the delay times and numerically apply our results to both the single and bimode states of a quantum cascade laser, in addition the effects of current injection on t{sub th} and Δt are explored.

  17. A dual-wavelength single particle aerosol fluorescence monitor

    Science.gov (United States)

    Kaye, Paul H.; Stanley, Warren R.; Foot, Virginia; Baxter, Karen; Barrington, Stephen J.

    2005-10-01

    Laser diodes and light-emitting diodes capable of continuous sub-300 nm radiation emission will ultimately represent optimal excitation sources for compact and fieldable bio-aerosol monitors. However, until such devices are routinely available and whilst solid-state UV lasers remain relatively expensive, other low-cost sources of UV can offer advantages. This paper describes one such prototype that employs compact xenon discharge UV sources to excite intrinsic fluorescence from individual particles within an ambient aerosol sample. The prototype monitor samples ambient air via a laminar sheathed-flow arrangement such that particles within the sample flow column are rendered in single file as they intersect the beam from a continuous-wave 660nm diode laser. Each individual particle produces a scattered light signal from which an estimate of particle size (down to ~1 um) may be derived. This same signal also initiates the sequential firing (~10 us apart) of two xenon sources which irradiate the particle with UV pulses centred upon ~280 nm and ~370 nm wavelength, optimal for excitation of bio-fluorophores tryptophan and NADH respectively. For each excitation wavelength, fluorescence is detected across two bands embracing the peak emissions of the same bio-fluorophores. Thus, for each particle, a 2-dimensional fluorescence excitation-emission matrix is recorded together with an estimate of particle size. Current measurement rates are up to ~125 particles/s (limited by the xenon recharge time), corresponding to all particles for concentrations up to ~2 x 104 particles/l. Developments to increase this to ~500 particles/s are in hand. Analysis of results from aerosols of E.coli, BG spores, and a variety of non-biological materials are given.

  18. 双波长比值光谱法测定银黄口服液中绿原酸和黄芩苷含量%Determination of chlorogenic acid and baicalin in Yinhuang oral solution by dual-wavelength ration spectrometry

    Institute of Scientific and Technical Information of China (English)

    孙增先; 李永溟; 李瑞真; 王奎兴; 张骞峰

    2001-01-01

    OBJECTIVE:To determine of chlorogenic acid and baicalin in Yinhuang oral solution by dual-wavelength ration spectrometry.METHODS:With the feature of ratio spectrometry for chlorogenic acid and baicalin,266 and 342nm were chosen as their determination wavelengthes.RESULTS:Linear range of chlorogenic acid and baicalin were 2~20μg/ml and 2~10μg/ml respectively.The recovery of chlorogenic acid and baicalin rate were 98.9%(RSD=1.58%) and 100.4%(RSD=1.32%) respectively.CONCLUSION:As a precise,accute and sample method,it could be spread to the assay of other traditional Chinese medicine products.%目的:应用双波长比值光谱法对银黄口服液中绿原酸和黄芩苷含量测定进行研究。方法:依据绿原酸和黄芩苷的比值光谱特征,选择266和342nm作为测定波长。结果:绿原酸线性范围2~20μg/ml,回收率98.9,RSD为1.58%;黄芩苷线性范围2~16μg/ml,回收率100.4%,RSD为1.32%。结论:本法为一种灵敏、准确和简便的分析方法,可在其他中药制剂中推广应用。

  19. A barrier radar concept

    Science.gov (United States)

    Marshall, J.; Ball, C.; Weissman, I.

    A description is given of a low power, light-weight radar that can be quickly set up and operated on batteries for extended periods of time to detect airborne intruders. With low equipment and operating costs, it becomes practical to employ a multiplicity of such radars to provide an unbroken intrusion fence over the desired perimeter. Each radar establishes a single transmitted fan beam extending vertically from horizon to horizon. The beam is generated by a two-face array antenna built in an A-frame configuration and is shaped, through phasing of the array elements, to concentrate the transmitter power in a manner consistent with the expected operating altitude ceiling of the targets of interest. The angular width of this beam in the dimension transverse to the fan depends on the radar transmission frequency and the antenna aperture dimension, but is typically wide enough so that a target at the maximum altitude or range will require tens of seconds to pass through the beam. A large number of independent samples of radar data will thus be available to provide many opportunities for target detection.

  20. Airport Surveillance Radar : Model 8 -

    Data.gov (United States)

    Department of Transportation — The Airport Surveillance Radar Model 8 (ASR-8) is a short-range (60 nautical mile (nmi)), analog radar system used to detect and report the presence and location of...

  1. Airport Surveillance Radar : Model 7 -

    Data.gov (United States)

    Department of Transportation — The Airport Surveillance Radar Model 7 (ASR-7) is a short-range (60 nautical miles (nmi)) analog radar system used to detect and report the presence and location of...

  2. Radar for tracer particles

    CERN Document Server

    Ott, Felix; Huang, Kai

    2016-01-01

    We introduce a radar system capable of tracking a $5$mm spherical target continuously in three dimensions. The $10$GHz (X-band) radar system has a transmission power of $1$W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-Mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the calibration, we reconstruct the target trajectory in a three-dimensional Cartesian system. Finally, we test the tracking algorithm with target moving in circular as well as in pendulum motions, and discuss the capability of the radar system.

  3. Localizing Ground-Penetrating Radar

    Science.gov (United States)

    2014-11-01

    ing Ground-Penetrating Radar (LGPR) uses very high frequency (VHF) radar reflections of underground features to generate base- line maps and then...Innovative ground- penetrating radar that maps underground geological features provides autonomous vehicles with real-time localization. Localizing...NOV 2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Localizing Ground-Penetrating Radar 5a. CONTRACT NUMBER

  4. Mode S Baseline Radar Tracking.

    Science.gov (United States)

    1982-11-01

    range units and 20 azimuth units) overlaying the position of the beacon reports. In the cases analyzed where beacon reports were not radar reinforced ...82/53 j~ C ~ 7 C _ _ _ _ _ _ 4. Title end Su.btitle 5. Neget at. November 1982 MDDE S BASELINE RADAR TRACKIN4G 6. Poelin Orgeuianti.. Cede ACT-100...Ground Clutter 33 Mode S/ARTS III 100-Scan False Radar Track Summary 74 34 Percent Beacon Radar Reinforcement 77 vii INTRODUCTION PURPOSE. The purpose of

  5. Systems and Methods for Radar Data Communication

    Science.gov (United States)

    Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

    2013-01-01

    A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

  6. Noise Radar Technology Basics

    Science.gov (United States)

    2006-12-01

    poursuite, estimation Doppler, polarimétrie, interférométrie, sondage du sol ou profilage de la sous- surface , détection, imagerie SAR (radar à synthèse...mesure de distance et d’estimation Doppler. Deux récepteurs de traitement cohérent, soit le récepteur de corrélation et le récep- teur de traitement DSP... traitement spectral double) des échos radar sont décrits et une estimation de leur portée est présentée. Les capacités LPI (faible probabilité

  7. Ground penetrating radar

    CERN Document Server

    Daniels, David J

    2004-01-01

    Ground-penetrating radar has come to public attention in recent criminal investigations, but has actually been a developing and maturing remote sensing field for some time. In the light of recent expansion of the technique to a wide range of applications, the need for an up-to-date reference has become pressing. This fully revised and expanded edition of the best-selling Surface-Penetrating Radar (IEE, 1996) presents, for the non-specialist user or engineer, all the key elements of this technique, which span several disciplines including electromagnetics, geophysics and signal processing. The

  8. Human walking estimation with radar

    NARCIS (Netherlands)

    Dorp, Ph. van; Groen, F.C.A.

    2003-01-01

    Radar can be used to observe humans that are obscured by objects such as walls. These humans cannot be visually observed. The radar measurements are used to animate an obscured human in virtual reality. This requires detailed information about the motion. The radar measurements give detailed informa

  9. Radar Test Range Design Considerations.

    Science.gov (United States)

    1980-04-29

    radar cross section associated with dihedral and trihedral corner reflectors is highly dependent upon the squareness or alignment of the...slightly misaligned. We now show how the radar cross section for dihedral and trihedral corner reflectors depends upon their surface misalignment. All...coefficients, p and q, for the dihedral corner reflector , one must consider the radar cross section

  10. Status Of Imaging Radar Polarimetry

    Science.gov (United States)

    Van Zyl, Jakob J.; Zebker, Howard A.

    1991-01-01

    Report pulls together information on imaging radar polarimetry from a variety of sources. Topics include theory, equipment, and experimental data. Reviews state of the art, examines current applicable developments in radar equipment, describes recording and processing of radar polarimetric measurements, and discusses interpretation and application of resulting polarimetric images.

  11. Human walking estimation with radar

    NARCIS (Netherlands)

    Dorp, Ph. van; Groen, F.C.A.

    2003-01-01

    Radar can be used to observe humans that are obscured by objects such as walls. These humans cannot be visually observed. The radar measurements are used to animate an obscured human in virtual reality. This requires detailed information about the motion. The radar measurements give detailed

  12. Coded continuous wave meteor radar

    OpenAIRE

    2015-01-01

    The concept of coded continuous wave meteor radar is introduced. The radar uses a continuously transmitted pseudo-random waveform, which has several advantages: coding avoids range aliased echoes, which are often seen with commonly used pulsed specular meteor radars (SMRs); continuous transmissions maximize pulse compression gain, allowing operation with significantly lower peak transmit power; the temporal resolution can be changed after ...

  13. A Revolutionary Wind and Precipitation Scanning Radar for Unmanned Aerial Vehicles Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives for the proposed Phase I study are: 1.Develop a compact, dual-wavelength antenna system capable of electronically scanning or producing...

  14. The Newcastle meteor radar

    Science.gov (United States)

    Keay, Colin

    1987-01-01

    A brief history and development of the Newcastle Meteor Radar system is given. Also described are its geographical coordinates and its method of operation. The initial objective when the project was commenced was to develop an entirely digital analyzer capable of recognizing meteor echo signals and recording as many of their parameters as possible. This objective was achieved.

  15. Compressive CFAR radar detection

    NARCIS (Netherlands)

    Anitori, L.; Otten, M.P.G.; Rossum, W.L. van; Maleki, A.; Baraniuk, R.

    2012-01-01

    In this paper we develop the first Compressive Sensing (CS) adaptive radar detector. We propose three novel architectures and demonstrate how a classical Constant False Alarm Rate (CFAR) detector can be combined with ℓ1-norm minimization. Using asymptotic arguments and the Complex Approximate Messag

  16. Compressive CFAR Radar Processing

    NARCIS (Netherlands)

    Anitori, L.; Rossum, W.L. van; Otten, M.P.G.; Maleki, A.; Baraniuk, R.

    2013-01-01

    In this paper we investigate the performance of a combined Compressive Sensing (CS) Constant False Alarm Rate (CFAR) radar processor under different interference scenarios using both the Cell Averaging (CA) and Order Statistic (OS) CFAR detectors. Using the properties of the Complex Approximate Mess

  17. Synthetic Aperture Radar Interferometry

    Science.gov (United States)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  18. Spaceborne Radar Study

    Science.gov (United States)

    1974-06-28

    via either the oomm beam or the omnichannel . Satellite instrumentation data are sent to the ground station following every radar signal transmission...If comm beam contact is lost, the instrumentation data are sent via the omnichannel transmitter on command of the ground station. There are six ways

  19. AMIE Gan Island Ancillary Disdrometer Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Oue, Mariko [Stony Brook Univ., NY (United States)

    2016-04-01

    As part of the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement Climate Research Facility (ARM) Madden-Julian Oscillation (MJO) Investigation Experiment (AMIE), in January 2012 a disdrometer observation took place with the second ARM Mobile Facility (AMF2), the Scanning ARM Cloud Radar (SACR), the Texas A&M SMART-R C-band radar, and the National Center for Atmospheric Research (NCAR) dual wavelength S- and Ka-bands polarimetric (SPolKa) radar on Gan Island, Maldives. In order to measure raindrop size distributions, a disdrometer of Nagoya University, Japan, was set up close to the ARM Two-Dimensional (2D) Video Disdrometer (2DVD). The SMART-R and SPolKa radars performed range-height-indicator scanning in the direction of the disdrometer site. Comparing the disdrometer data with 2DVD data, the raindrop size distribution data will be calibrated. Furthermore, the analysis of the raindrop size distribution and radar data will be expected to clarify the microphysics in tropical convective clouds.

  20. Using the Rapid-Scanning, Ultra-Portable, Canopy Biomass Lidar (CBL) Alone and In Tandem with the Full-Waveform Dual-Wavelength Echidna® Lidar (DWEL) to Establish Forest Structure and Biomass Estimates in a Variety of Ecosystems

    Science.gov (United States)

    Schaaf, C.; Paynter, I.; Saenz, E. J.; Li, Z.; Strahler, A. H.; Peri, F.; Erb, A.; Raumonen, P.; Muir, J.; Howe, G.; Hewawasam, K.; Martel, J.; Douglas, E. S.; Chakrabarti, S.; Cook, T.; Schaefer, M.; Newnham, G.; Jupp, D. L. B.; van Aardt, J. A.; Kelbe, D.; Romanczyk, P.; Faulring, J.

    2014-12-01

    Terrestrial lidars are increasingly being deployed in a variety of ecosystems to calibrate and validate large scale airborne and spaceborne estimates of forest structure and biomass. While these lidars provide a wealth of high resolution information on canopy structure and understory vegetation, they tend to be expensive, slow scanning and somewhat ponderous to deploy. Therefore, frequent deployments and characterization of larger areas of a hectare or more can still be challenging. This suggests a role for low cost, ultra-portable, rapid scanning (but lower resolution) instruments -- particularly in scanning extreme environments and as a way to augment and extend strategically placed scans from the more highly capable lidars. The Canopy Biomass Lidar (CBL) is an inexpensive, highly portable, fast-scanning (33 seconds), time-of-flight, terrestrial laser scanning (TLS) instrument, built in collaboration with RIT, by U Mass Boston. The instrument uses a 905nm SICK time of flight laser with a 0.25o resolution and 30m range. The higher resolution, full-waveform Dual Wavelength Echidna® Lidar (DWEL), developed by Boston University, U Mass Lowell and U Mass Boston, builds on the Australian CSIRO single wavelength, full-waveform Echidna® Validation Instrument (EVI), but utilizes two simultaneous laser pulses at 1064 and 1548 nm to separate woody returns from those of foliage at a range of up to 100m range. The UMass Boston CBL has been deployed in rangelands (San Joaquin Experimental Range, CA), high altitude conifers (Sierra National Forest, CA), mixed forests (Harvard Forest LTER MA), tropical forests (La Selva and Sirena Biological Stations, Costa Rica), eucalypts (Karawatha, Brisbane TERN, Australia), and woodlands (Alice Holt Forest, UK), frequently along-side the DWEL, as well as in more challenging environments such as mangrove forests (Corcovado National Park, Costa Rica) and Massachusetts salt marshes and eroding bluffs (Plum Island LTER, and UMass Boston