Verification Test for Ultra-Light Deployment Mechanism for Sectioned Deployable Antenna Reflectors

Science.gov (United States)

Zajac, Kai; Schmidt, Tilo; Schiller, Marko; Seifart, Klaus; Schmalbach, Matthias; Scolamiero, Lucio

2013-09-01

The ultra-light deployment mechanism (UDM) is based on three carbon fibre reinforced plastics (CFRP) curved tape springs made of carbon fibre / cyanate ester prepregs.In the frame of the activity its space application suitability for the deployment of solid reflector antenna sections was investigated. A projected diameter of the full reflector of 4 m to 7 m and specific mass in the order of magnitude of 2.6kg/m2 was focused for requirement derivation.Extensive verification tests including health checks, environmental and functional tests were carried out with an engineering model to enable representative characterizing of the UDM unit.This paper presents the design and a technical description of the UDM as well as a summary of achieved development status with respect to test results and possible design improvements.

Shaping Single Offset Reflector Antennas Using Local Axis-Displaced Confocal Quadrics

Directory of Open Access Journals (Sweden)

Rafael A. Penchel

2016-01-01

Full Text Available This work investigates a novel numerical procedure for the solution of an exact formulation for the Geometrical Optics synthesis of a single reflector antenna by simultaneously imposing Snell’s Law and Conservation of Energy in a tube of rays, yielding a second-order nonlinear partial differential equation of Monge-Ampère type, which can be solved as a boundary value problem. The investigation explores the interpolating properties of confocal quadrics to locally represent the shaped reflector surface. It allows the partial derivatives involved in the formulation to be analytically expressed. To illustrate the method, two examples of offset single reflectors shaped to radiate a Gaussian power density within a superelliptical contoured beam are presented. The results are validated by Physical Optics analysis with equivalent edge currents.

Triple-Notched Band CPW fed UWB Antenna with Metallic Reflector for High Gain Performance

Directory of Open Access Journals (Sweden)

K. G. Jangid

2017-10-01

Full Text Available This paper exhibits the design and performance of a coplanar waveguide (CPW fed triple notched band ultra-wide band (UWB antenna. Proposed prototype has two U-shaped slots on the patch and an inverted U slot in feed line with a metal reflector beneath the radiating element. Proposed structure renders wider impedance bandwidth extended between frequencies 2.71GHz to 12.92 GHz for VSWR 2. The utmost simulated gain of proposed antenna with reflector is close to 9.9dBi at 7.4GHz. A sharp reduction observed in the efficiency values of the proposed structure at stop bands. Perhaps, this structure proved as a useful tool for various applications in modern communication systems including UWB.

Beam scanning offset Casegrain reflector antennas by subreflector movement

OpenAIRE

LaPean, James William

1993-01-01

In 1987 a NASA panel recommended the creation of the Mission to Planet Earth. This mission was intended to apply to remote sensing experience of the space community to earth remote sensing to enhance the understanding of the climatalogical processes of our planet and to determine if, and to what extent, the hydrological cycle of Earth is being affected by human activity. One of the systems required for the mission was a wide scanning, high gain reflector antenna system for use ...

Analysis of Arbitrary Reflector Antennas Applying the Geometrical Theory of Diffraction Together with the Master Points Technique

Directory of Open Access Journals (Sweden)

María Jesús Algar

2013-01-01

Full Text Available An efficient approach for the analysis of surface conformed reflector antennas fed arbitrarily is presented. The near field in a large number of sampling points in the aperture of the reflector is obtained applying the Geometrical Theory of Diffraction (GTD. A new technique named Master Points has been developed to reduce the complexity of the ray-tracing computations. The combination of both GTD and Master Points reduces the time requirements of this kind of analysis. To validate the new approach, several reflectors and the effects on the radiation pattern caused by shifting the feed and introducing different obstacles have been considered concerning both simple and complex geometries. The results of these analyses have been compared with the Method of Moments (MoM results.

Development of Full-Scale Ultrathin Shell Reflector

Directory of Open Access Journals (Sweden)

Durmuş Türkmen

2012-01-01

Full Text Available It is aimed that a new ultrathin shell composite reflector is developed considering different design options to optimize the stiffness/mass ratio, cost, and manufacturing. The reflector is an offset parabolic reflector with a diameter of 6 m, a focal length of 4.8 m, and an offset of 0.3 m and has the ability of folding and self-deploying. For Ku-band missions a full-scale offset parabolic reflector antenna is designed by considering different concepts of stiffening: (i reflective surface and skirt, (ii reflective surface and radial ribs, and (iii reflective surface, skirt, and radial ribs. In a preliminary study, the options are modeled using ABAQUS finite element program and compared with respect to their mass, fundamental frequency, and thermal surface errors. It is found that the option of reflective surface and skirt is more advantageous. The option is further analyzed to optimize the stiffness/mass ratio considering the design parameters of material thickness, width of the skirt, and ply angles. Using the TOPSIS method is determined the best reflector concept among thirty different designs. Accordingly, new design can be said to have some advantages in terms of mass, natural frequency, number of parts, production, and assembly than both SSBR and AstroMesh reflectors.

GO Shaping of Omnidirectional Dual-Reflector Antennas with Arbitrary Main-Beam Direction in Elevation Plane by Connecting Conic Sections

Directory of Open Access Journals (Sweden)

Rafael A. Penchel

2018-01-01

Full Text Available This work discusses an alternative geometrical optics (GO technique to synthesize omnidirectional dual-reflector antennas with uniform aperture phase distribution together with an arbitrary main-beam direction for the antenna radiation pattern. Sub- and main reflectors are bodies of revolution generated by shaped curves defined by local conic sections consecutively concatenated. The shaping formulation is derived for configurations like ADC (axis-displaced Cassegrain and ADE (axis-displaced ellipse omnidirectional antennas. As case studies, two configurations fed by a TEM coaxial horn are designed and analyzed by a hybrid technique based on mode matching and method of moments in order to validate the GO shaping procedure.

Square Van Atta reflector with conducting mounting flame

DEFF Research Database (Denmark)

Nielsen, Erik Dragø

1970-01-01

A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs by transmiss......A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs...

Flexible-Robotic Reflector for Aerospace Applications

Directory of Open Access Journals (Sweden)

Nir Shvalb

2015-01-01

Full Text Available Existing dish based antennas tend to have geometric morphologic distortion in the surface due to drastic thermal changes common in the space environment. In this paper we present a new concept for a dynamic antenna specially designed for communication satellites. The suggested flexible-robotic antenna is based on a dual-reflector structure, where the subreflector has a complex surface shaping robotic mechanism allowing it to fix most of the morphologic errors in the main reflector. We have implemented a set of searching algorithms allowing the hyper redundant robotic subreflector to adapt its surface to the morphologic distortions in the main reflector. The suggested new antenna was constructed and tested in an RF room in which it was able to fix the loss caused by distortion in the main reflector to the original gain in less than an hour.

Dynamics of large reflectors - Aerospatiale concepts

Science.gov (United States)

Flechais, A.; Picard, P.; Dauviau, C.; Truchi, C.

1992-08-01

An overview is presented of studies performed under an ESTEC contract and aimed at the identification of critical development areas of unfurlable reflectors and at the analysis of the dynamic interactions between reflectors and hosting spacecraft, in particular with respect to the design of the AOCS and antenna pointing mechanism (APM). Research and development performed by Aerospatiale since 1983 in the field of unfurlable mesh reflectors and supported by CNES are summarized. An analysis covering both the deployment phase and the deployed configuration is presented. The capabilities of classical AOCS and APM control laws for large reflectors are evaluated via simulations. It is shown that the baseline reflector under consideration is compatible with the PSDE mission and classical AOCS and APM control law designs.

Metasurface Reflector (MSR) Loading for High Performance Small Microstrip Antenna Design.

Science.gov (United States)

Ahsan, Md Rezwanul; Islam, Mohammad Tariqul; Ullah, Mohammad Habib; Singh, Mandeep Jit; Ali, Mohd Tarmizi

2015-01-01

A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR) structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15) is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10 dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%), 467 to 606 MHz (29%) and 758 MHz to 1062 MHz (40%) for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11WLAN (5.2/5.8 GHz) applications.

Metasurface Reflector (MSR Loading for High Performance Small Microstrip Antenna Design.

Directory of Open Access Journals (Sweden)

Md Rezwanul Ahsan

Full Text Available A meander stripline feed multiband microstrip antenna loaded with metasurface reflector (MSR structure has been designed, analyzed and constructed that offers the wireless communication services for UHF/microwave RFID and WLAN/WiMAX applications. The proposed MSR assimilated antenna comprises planar straight forward design of circular shaped radiator with horizontal slots on it and 2D metasurface formed by the periodic square metallic element that resembles the behavior of metamaterials. A custom made high dielectric bio-plastic substrate (εr = 15 is used for fabricating the prototype of the MSR embedded planar monopole antenna. The details of the design progress through numerical simulations and experimental results are presented and discussed accordingly. The measured impedance bandwidth, radiation patterns and gain of the proposed MSR integrated antenna are compared with the obtained results from numerical simulation, and a good compliance can be observed between them. The investigation shows that utilization of MSR structure has significantly broadened the -10 dB impedance bandwidth than the conventional patch antenna: from 540 to 632 MHz (17%, 467 to 606 MHz (29% and 758 MHz to 1062 MHz (40% for three distinct operating bands centered at 0.9, 3.5 and 5.5 GHz. Additionally, due to the assimilation of MSR, the overall realized gains have been upgraded to a higher value of 3.62 dBi, 6.09 dBi and 8.6 dBi for lower, middle and upper frequency band respectively. The measured radiation patterns, impedance bandwidths (S11<-10 dB and gains from the MSR loaded antenna prototype exhibit reasonable characteristics that can satisfy the requirements of UHF/microwave (5.8 GHz RFID, WiMAX (3.5/5.5 GHz and WLAN (5.2/5.8 GHz applications.

Millimeter Wave Imaging System Using Monopole Antenna with Cylindrical Reflector and Silicon Lens

Science.gov (United States)

Mizuno, Maya; Fukunaga, Kaori; Suzuki, Masaki; Saito, Shingo; Fujii, Katsumi; Hosako, Iwao; Yamanaka, Yukio

2011-04-01

We built a reflection imaging system that uses a monopole antenna with a cylindrical reflector and silicon semi-spherical lens for millimeter waves to identify detachments of alabaster from support material such as wood and stone, which can be subject to painting deterioration. Based on the electric field property near the monopole antenna in the system and the lens effect, the system was able to clearly image a test sample made of 2-mm width aluminium tape, which was placed within a range of approximately 10 mm from the lens. In practical imaging testing using a detachment model, which consists of alabaster and wood plating, the result also showed the possibility of observing slight detachment of the alabaster from the wood more easily than an imaging with large numerical aperture.

Directional borehole antenna - Theory

International Nuclear Information System (INIS)

Falk, L.

1992-02-01

A directional antenna has been developed for the borehole radar constructed during phase 2 of the Stripa project. The new antenna can determine the azimuth of a strong reflector with an accuracy of about 3 degrees as confirmed during experiments in Stripa, although the ratio of borehole diameter to wavelength is small, about 0.03. The antenna synthesizes the effect of a loop antenna rotating in the borehole from four signals measured in turn by a stationary antenna. These signals are also used to calculate an electric dipole signal and a check sum which is used to examine the function of the system. The theory of directional antennas is reviewed and used to design an antenna consisting of four parallel wires. The radiation pattern of this antenna is calculated using transmission line theory with due regard to polarization, which is of fundamental importance for the analysis of directional data. In particular the multipole expansion of the field is calculated to describe the antenna radiation pattern. Various sources of error, e.g. the effect of the borehole, are discussed and the methods of calibrating the antenna are reviewed. The ambiguity inherent in a loop antenna can be removed by taking the phase of the signal into account. Typical reflectors in rock, e.g. fracture zones an tunnels, may be modelled as simple geometrical structures. The corresponding analysis is described and exemplified on measurements from Stripa. Radar data is nowadays usually analyzed directly on the computer screen using the program RADINTER developed within the Stripa project. An algorithm for automatic estimation of the parameters of a reflector have been tested with some success. The relation between measured radar data and external coordinates as determined by rotational indicators is finally expressed in terms of Euler angles. (au)

A Dual-Wideband Double-Layer Magnetoelectric Dipole Antenna with a Modified Horned Reflector for 2G/3G/LTE Applications

Directory of Open Access Journals (Sweden)

Botao Feng

2013-01-01

Full Text Available A novel dual-wideband double-layer magnetoelectric dipole unidirectional antenna with a modified horned reflector for 2G/3G/LTE applications is proposed. Firstly, a double-layer electric dipole structure is presented to provide a dualwideband, whose folded lower layer mainly serves the lower frequency band while the inclined upper layer works for the upper frequency band. In addition, to reduce the size of the antenna and improve impedance matching, a new feeding structure designed with inverted U-shaped and tapered line is introduced. Finally, a modified horn-shaped reflector, instead of a ground plane, is employed to achieve stable and high gains. The antenna prototype can achieve a bandwidth of 24.4% (790 MHz–1010 MHz with a stable gain of 7.2 ± 0.6 dBi for the lower band, and a bandwidth of 67.3% (1.38 GHz–2.78 GHz with a gain of 7.5 ± 0.8 dBi for the upper band covering all the frequency bands for 2G/3G/LTE systems. To the best of our knowledge, it is the first double-layer magnetoelectric dipole antenna proposed. Compared with the existing ME dipole antennas, the proposed antenna, which is completely made of copper, can be easily fabricated at low cost and thus is practicable for 2G/3G/LTE applications.

Dual-shaped offset reflector antenna designs from solutions of the geometrical optics first-order partial differential equations

Science.gov (United States)

Galindo-Israel, V.; Imbriale, W.; Shogen, K.; Mittra, R.

1990-01-01

In obtaining solutions to the first-order nonlinear partial differential equations (PDEs) for synthesizing offset dual-shaped reflectors, it is found that previously observed computational problems can be avoided if the integration of the PDEs is started from an inner projected perimeter and integrated outward rather than starting from an outer projected perimeter and integrating inward. This procedure, however, introduces a new parameter, the main reflector inner perimeter radius p(o), when given a subreflector inner angle 0(o). Furthermore, a desired outer projected perimeter (e.g., a circle) is no longer guaranteed. Stability of the integration is maintained if some of the initial parameters are determined first from an approximate solution to the PDEs. A one-, two-, or three-parameter optimization algorithm can then be used to obtain a best set of parameters yielding a close fit to the desired projected outer rim. Good low cross-polarization mapping functions are also obtained. These methods are illustrated by synthesis of a high-gain offset-shaped Cassegrainian antenna and a low-noise offset-shaped Gregorian antenna.

Design of cost effective antennas for instrumentation radars

CSIR Research Space (South Africa)

Botha, L

2012-09-01

Full Text Available The cost of antennas for instrumentation radars are determined by the development cost. By re-use of the reflector system cost effective antennas can be designed. The factors governing the design of such antennas are described here....

Development of optical ground verification method for μm to sub-mm reflectors

Science.gov (United States)

Stockman, Y.; Thizy, C.; Lemaire, P.; Georges, M.; Mazy, E.; Mazzoli, A.; Houbrechts, Y.; Rochus, P.; Roose, S.; Doyle, D.; Ulbrich, G.

2017-11-01

Large reflectors and antennas for the IR to mm wavelength range are being planned for many Earth observation and astronomical space missions and for commercial communication satellites as well. Scientific observatories require large telescopes with precisely shaped reflectors for collecting the electro-magnetic radiation from faint sources. The challenging tasks of on-ground testing are to achieve the required accuracy in the measurement of the reflector shapes and antenna structures and to verify their performance under simulated space conditions (vacuum, low temperatures). Due to the specific surface characteristics of reflectors operating in these spectral regions, standard optical metrology methods employed in the visible spectrum do not provide useful measurement results. The current state-of-the-art commercial metrology systems are not able to measure these types of reflectors because they have to face the measurement of shape and waviness over relatively large areas with a large deformation dynamic range and encompassing a wide range of spatial frequencies. 3-D metrology (tactile coordinate measurement) machines are generally used during the manufacturing process. Unfortunately, these instruments cannot be used in the operational environmental conditions of the reflector. The application of standard visible wavelength interferometric methods is very limited or impossible due to the large relative surface roughnesses involved. A small number of infrared interferometers have been commercially developed over the last 10 years but their applications have also been limited due to poor dynamic range and the restricted spatial resolution of their detectors. These restrictions affect also the surface error slopes that can be captured and makes their application to surfaces manufactured using CRFP honeycomb technologies rather difficult or impossible. It has therefore been considered essential, from the viewpoint of supporting future ESA exploration missions, to

Active Surface Compensation for Large Radio Telescope Antennas

Directory of Open Access Journals (Sweden)

Congsi Wang

2018-01-01

Full Text Available With the development of radio telescope antennas with large apertures, high gain, and wide frequency bands, compensation methods, such as mechanical or electronic compensation, are obviously essential to ensure the electrical performance of antennas that work in complex environments. Since traditional compensation methods can only adjust antenna pointing but not the surface accuracy, which are limited for obtaining high surface precision and aperture efficiency, active surface adjustment has become an indispensable tool in this field. Therefore, the development process of electrical performance compensation methods for radio telescope antennas is introduced. Further, a series of analyses of the five key technologies of active surface adjustment is presented. Then, four typical large antennas that have been designed with active main reflector technology are presented and compared. Finally, future research directions and suggestions for reflector antenna compensation methods based on active surface adjustment are presented.

Stochastic and sensitivity analysis of shape error of inflatable antenna reflectors

Science.gov (United States)

San, Bingbing; Yang, Qingshan; Yin, Liwei

2017-03-01

Inflatable antennas are promising candidates to realize future satellite communications and space observations since they are lightweight, low-cost and small-packaged-volume. However, due to their high flexibility, inflatable reflectors are difficult to manufacture accurately, which may result in undesirable shape errors, and thus affect their performance negatively. In this paper, the stochastic characteristics of shape errors induced during manufacturing process are investigated using Latin hypercube sampling coupled with manufacture simulations. Four main random error sources are involved, including errors in membrane thickness, errors in elastic modulus of membrane, boundary deviations and pressure variations. Using regression and correlation analysis, a global sensitivity study is conducted to rank the importance of these error sources. This global sensitivity analysis is novel in that it can take into account the random variation and the interaction between error sources. Analyses are parametrically carried out with various focal-length-to-diameter ratios (F/D) and aperture sizes (D) of reflectors to investigate their effects on significance ranking of error sources. The research reveals that RMS (Root Mean Square) of shape error is a random quantity with an exponent probability distribution and features great dispersion; with the increase of F/D and D, both mean value and standard deviation of shape errors are increased; in the proposed range, the significance ranking of error sources is independent of F/D and D; boundary deviation imposes the greatest effect with a much higher weight than the others; pressure variation ranks the second; error in thickness and elastic modulus of membrane ranks the last with very close sensitivities to pressure variation. Finally, suggestions are given for the control of the shape accuracy of reflectors and allowable values of error sources are proposed from the perspective of reliability.

Analysis of acoustic reflectors for SAW temperature sensor and wireless measurement of temperature

International Nuclear Information System (INIS)

Kim, Ki Bok; Kim, Seong Hoon; Jeong, Jae Kee; Shin, Beom Soo

2013-01-01

In this study, a wireless and non power SAW (surface acoustic wave) temperature sensor was developed. The single inter digital transducer (IDT) of SAW temperature sensor of which resonance frequency is 434 MHz was fabricated on 128.deg rot-X LiNbO 3 piezoelectric substrate by semiconductor processing technology. To find optimal acoustic reflector for SAW temperature sensor, various kinds of acoustic reflectors were fabricated and their reflection characteristics were analyzed. The IDT type acoustic reflector showed better reflection characteristic than other reflectors. The wireless temperature sensing system consisting of SAW temperature sensor with dipole antenna and a microprocessor based control circuit with dipole antenna for transmitting signal to activate the SAW temperature sensor and receiving the signal from SAW temperature sensor was developed. The result with wireless SAW temperature sensing system showed that the frequency of SAW temperature sensor was linearly decreased with the increase of temperature in the range of 40 to 80.deg.C and the developed wireless SAW temperature sensing system showed the excellent performance with the coefficient of determination of 0.99

Application of Vision Metrology to In-Orbit Measurement of Large Reflector Onboard Communication Satellite for Next Generation Mobile Satellite Communication

Science.gov (United States)

Akioka, M.; Orikasa, T.; Satoh, M.; Miura, A.; Tsuji, H.; Toyoshima, M.; Fujino, Y.

2016-06-01

Satellite for next generation mobile satellite communication service with small personal terminal requires onboard antenna with very large aperture reflector larger than twenty meters diameter because small personal terminal with lower power consumption in ground base requires the large onboard reflector with high antenna gain. But, large deployable antenna will deform in orbit because the antenna is not a solid dish but the flexible structure with fine cable and mesh supported by truss. Deformation of reflector shape deteriorate the antenna performance and quality and stability of communication service. However, in case of digital beam forming antenna with phased array can modify the antenna beam performance due to adjustment of excitation amplitude and excitation phase. If we can measure the reflector shape precisely in orbit, beam pattern and antenna performance can be compensated with the updated excitation amplitude and excitation phase parameters optimized for the reflector shape measured every moment. Softbank Corporation and National Institute of Information and Communications Technology has started the project "R&D on dynamic beam control technique for next generation mobile communication satellite" as a contracted research project sponsored by Ministry of Internal Affairs and Communication of Japan. In this topic, one of the problem in vision metrology application is a strong constraints on geometry for camera arrangement on satellite bus with very limited space. On satellite in orbit, we cannot take many images from many different directions as ordinary vision metrology measurement and the available area for camera positioning is quite limited. Feasibility of vision metrology application and general methodology to apply to future mobile satellite communication satellite is to be found. Our approach is as follows: 1) Development of prototyping simulator to evaluate the expected precision for network design in zero order and first order 2) Trial

Large space antenna communications systems: Integrated Langley Research Center/Jet Propulsion Laboratory development activities. 2: Langley Research Center activities

Science.gov (United States)

Cambell, T. G.; Bailey, M. C.; Cockrell, C. R.; Beck, F. B.

1983-01-01

The electromagnetic analysis activities at the Langley Research Center are resulting in efficient and accurate analytical methods for predicting both far- and near-field radiation characteristics of large offset multiple-beam multiple-aperture mesh reflector antennas. The utilization of aperture integration augmented with Geometrical Theory of Diffraction in analyzing the large reflector antenna system is emphasized.

The geometrical theory of diffraction for axially symmetric reflectors

DEFF Research Database (Denmark)

Rusch, W.; Sørensen, O.

1975-01-01

The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...

Large space antenna concepts for ESGP

Science.gov (United States)

Love, Allan W.

1989-01-01

It is appropriate to note that 1988 marks the 100th anniversary of the birth of the reflector antenna. It was in 1888 that Heinrich Hertz constructed the first one, a parabolic cylinder made of sheet zinc bent to shape and supported by a wooden frame. Hertz demonstrated the existence of the electromagnetic waves that had been predicted theoretically by James Clerk Maxwell some 22 years earlier. In the 100 years since Hertz's pioneering work the field of electromagnetics has grown explosively: one of the technologies is that of remote sensing of planet Earth by means of electromagnetic waves, using both passive and active sensors located on an Earth Science Geostationary Platform (ESEP). For these purposes some exquisitely sensitive instruments were developed, capable of reaching to the fringes of the known universe, and relying on large reflector antennas to collect the minute signals and direct them to appropriate receiving devices. These antennas are electrically large, with diameters of 3000 to 10,000 wavelengths and with gains approaching 80 to 90 dB. Some of the reflector antennas proposed for ESGP are also electrically large. For example, at 220 GHz a 4-meter reflector is nearly 3000 wavelengths in diameter, and is electrically quite comparable with a number of the millimeter wave radiotelescopes that are being built around the world. Its surface must meet stringent requirements on rms smoothness, and ability to resist deformation. Here, however, the environmental forces at work are different. There are no varying forces due to wind and gravity, but inertial forces due to mechanical scanning must be reckoned with. With this form of beam scanning, minimizing momentum transfer to the space platform is a problem that demands an answer. Finally, reflector surface distortion due to thermal gradients caused by the solar flux probably represents the most challenging problem to be solved if these Large Space Antennas are to achieve the gain and resolution required of

Antennas for mobile satellite communications

Science.gov (United States)

Huang, John

1991-12-01

A NASA sponsored program, called the Mobile Satellite (MSAT) system, has prompted the development of several innovative antennas at L-band frequencies. In the space segment of the MSAT system, an efficient, light weight, circularly polarized microstrip array that uses linearly polarized elements was developed as a multiple beam reflector feed system. In the ground segment, a low-cost, low-profile, and very efficient microstrip Yagi array was developed as a medium-gain mechanically steered vehicle antenna. Circularly shaped microstrip patches excited at higher-order modes were also developed as low-gain vehicle antennas. A more recent effort called for the development of a 20/30 GHz mobile terminal antenna for future-generation mobile satellite communications. To combat the high insertion loss encountered at 20/30 GHz, series-fed Monolithic Microwave Integrated Circuit (MMIC) microstrip array antennas are currently being developed. These MMIC arrays may lead to the development of several small but high-gain Ka-band antennas for the Personal Access Satellite Service planned for the 2000s.

Measurement of electrostatically formed antennas using photogrammetry and theodolites

Science.gov (United States)

Goslee, J. W.; Hinson, W. F.; Kennefick, J. F.; Mihora, D. J.

1984-01-01

An antenna concept is presently being evaluated which has extremely low mass and high surface precision for potential depolyment from the Space Shuttle. This antenna concept derives its reflector surface quality from the application of electrostatic forces to tension and form a thin membrane into the desired concave reflector surface. The Shuttle-deployed antenna would have a diameter of 100 meters and an RMS surface smoothness of 10 to 1 mm for operation at 1 to 10 GHz. NASA Langley Research Center (LaRC) has built, and is currently testing, a subscale (1/20 scale) membrane reflector model of such an antenna. Several surface measurement systems were evaluated as part of the experimental surface measuring efforts. The surface measurement systems are addressed as well as some of the preliminary measurement results.

Advanced Communication Technology Satellite (ACTS) multibeam antenna analysis and experiment

Science.gov (United States)

Acosta, Roberto J.; Lagin, Alan R.; Larko, Jeffrey M.; Narvaez, Adabelle

1992-01-01

One of the most important aspects of a satellite communication system design is the accurate estimation of antenna performance degradation. Pointing error, end coverage gain, peak gain degradation, etc. are the main concerns. The thermal or dynamic distortions of a reflector antenna structural system can affect the far-field antenna power distribution in a least four ways. (1) The antenna gain is reduced; (2) the main lobe of the antenna can be mispointed thus shifting the destination of the delivered power away from the desired locations; (3) the main lobe of the antenna pattern can be broadened, thus spreading the RF power over a larger area than desired; and (4) the antenna pattern sidelobes can increase, thus increasing the chances of interference among adjacent beams of multiple beam antenna system or with antenna beams of other satellites. The in-house developed NASA Lewis Research Center thermal/structural/RF analysis program was designed to accurately simulate the ACTS in-orbit thermal environment and predict the RF antenna performance. The program combines well establish computer programs (TRASYS, SINDA and NASTAN) with a dual reflector-physical optics RF analysis program. The ACTS multibeam antenna configuration is analyzed and several thermal cases are presented and compared with measurements (pre-flight).

A note on antennas: Definitions and methods

DEFF Research Database (Denmark)

Bach, Henning

1987-01-01

Definitions of scattered and diffracted fields, originally given by R. F. Millar, are reviewed and supplemented. The definitions are used to discuss relations between results obtained by commonly used pattern prediction methods for reflector antennas.......Definitions of scattered and diffracted fields, originally given by R. F. Millar, are reviewed and supplemented. The definitions are used to discuss relations between results obtained by commonly used pattern prediction methods for reflector antennas....

Analysis of the Thermo-Elastic Response of Space Reflectors to Simulated Space Environment

Science.gov (United States)

Allegri, G.; Ivagnes, M. M.; Marchetti, M.; Poscente, F.

2002-01-01

The evaluation of space environment effects on materials and structures is a key matter to develop a proper design of long duration missions: since a large part of satellites operating in the earth orbital environment are employed for telecommunications, the development of space antennas and reflectors featured by high dimensional stability versus space environment interactions represents a major challenge for designers. The structural layout of state of the art space antennas and reflectors is very complex, since several different sensible elements and materials are employed: particular care must be placed in evaluating the actual geometrical configuration of the reflectors operating in the space environment, since very limited distortions of the designed layout can produce severe effects on the quality of the signal both received and transmitted, especially for antennas operating at high frequencies. The effects of thermal loads due to direct sunlight exposition and to earth and moon albedo can be easily taken into account employing the standard methods of structural analysis: on the other hand the thermal cycling and the exposition to the vacuum environment produce a long term damage accumulation which affects the whole structure. The typical effects of the just mentioned exposition are the outgassing of polymeric materials and the contamination of the exposed surface, which can affect sensibly the thermo-mechanical properties of the materials themselves and, therefore, the structural global response. The main aim of the present paper is to evaluate the synergistic effects of thermal cycling and of the exposition to high vacuum environment on an innovative antenna developed by Alenia Spazio S.p.a.: to this purpose, both an experimental and numerical research activity has been developed. A complete prototype of the antenna has been exposed to the space environment simulated by the SAS facility: this latter is constituted by an high vacuum chamber, equipped by

Application of the SWE-to-PWE antenna diagnostics technique to an offset reflector antenna

DEFF Research Database (Denmark)

Cappellin, Cecilia; Frandsen, Aksel; Breinbjerg, Olav

2008-01-01

Electrical and mechanical errors in an antenna may seriously affect the antenna's performance. Although their presence is usually detected by anomalies in the antenna's far-field pattern, their identification is normally possible only through an analysis of the antenna's extreme near field....... The reconstruction of the extreme near field on the basis of near- or far-field measurements is thus an essential step in antenna diagnostics....

Compact Antenna Range

Data.gov (United States)

Federal Laboratory Consortium — Facility consists of a folded compact antenna range including a computer controlled three axis position table, parabolic reflector and RF sources for the measurement...

Rotating Parabolic-Reflector Antenna Target in SAR Data: Model, Characteristics, and Parameter Estimation

Directory of Open Access Journals (Sweden)

Bin Deng

2013-01-01

Full Text Available Parabolic-reflector antennas (PRAs, usually possessing rotation, are a particular type of targets of potential interest to the synthetic aperture radar (SAR community. This paper is aimed to investigate PRA’s scattering characteristics and then to extract PRA’s parameters from SAR returns, for supporting image interpretation and target recognition. We at first obtain both closed-form and numeric solutions to PRA’s backscattering by geometrical optics (GO, physical optics, and graphical electromagnetic computation, respectively. Based on the GO solution, a migratory scattering center model is at first presented for representing the movement of the specular point with aspect angle, and then a hybrid model, named the migratory/micromotion scattering center (MMSC model, is proposed for characterizing a rotating PRA in the SAR geometry, which incorporates PRA’s rotation into its migratory scattering center model. Additionally, we in detail analyze PRA’s radar characteristics on radar cross-section, high-resolution range profiles, time-frequency distribution, and 2D images, which also confirm the models proposed. A maximal likelihood estimator is developed for jointly solving the MMSC model for PRA’s multiple parameters by optimization. By exploiting the aforementioned characteristics, the coarse parameter estimation guarantees convergency upon global minima. The signatures recovered can be favorably utilized for SAR image interpretation and target recognition.

Cellular Reflectarray Antenna

Science.gov (United States)

Romanofsky, Robert R.

2010-01-01

The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

Millimeter-wave antennas configurations and applications

CERN Document Server

du Preez, Jaco

2016-01-01

This book comprehensively reviews the state of the art in millimeter-wave antennas, traces important recent developments and provides information on a wide range of antenna configurations and applications. While fundamental theoretical aspects are discussed whenever necessary, the book primarily focuses on design principles and concepts, manufacture, measurement techniques, and practical results. Each of the various antenna types scalable to millimeter-wave dimensions is considered individually, with coverage of leaky-wave and surface-wave antennas, printed antennas, integrated antennas, and reflector and lens systems. The final two chapters address the subject from a systems perspective, providing an overview of supporting circuitry and examining in detail diverse millimeter-wave applications, including high-speed wireless communications, radio astronomy, and radar. The vast amount of information now available on millimeter-wave systems can be daunting for researchers and designers entering the field. This b...

Experiments with dipole antennas

International Nuclear Information System (INIS)

Kraftmakher, Yaakov

2009-01-01

Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a variant of the Yagi-Uda antenna is explored. The experiments are suitable as laboratory works and classroom demonstrations, and are attractive for student projects.

Fundamentals of antennas concepts and applications

CERN Document Server

Christodoulou, Christos G

2001-01-01

This tutorial explains antenna design and application for various systems, including communications, remote sensing, radar, and biomedicine. It describes basic wire and array antennas in detail and introduces other types such as reflectors, lenses, horns, Yagi, microstrip, and frequency-independent antennas. Integration issues and technical challenges are discussed. Aimed at students, engineers, researchers, and technical professionals.

Backfire antennas with dipole elements

DEFF Research Database (Denmark)

Nielsen, Erik Dragø; Pontoppidan, Knud

1970-01-01

A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...

Radio telescope reflectors historical development of design and construction

CERN Document Server

Baars, Jacob W M

2018-01-01

This book demonstrates how progress in radio astronomy is intimately linked to the development of reflector antennas of increasing size and precision. The authors describe the design and construction of major radio telescopes as those in Dwingeloo, Jodrell Bank, Parkes, Effelsberg and Green Bank since 1950 up to the present as well as millimeter wavelength telescopes as the 30m MRT of IRAM in Spain, the 50m LMT in Mexico and the ALMA submillimeter instrument. The advances in methods of structural design and coping with environmental influences (wind, temperature, gravity) as well as application of new materials are explained in a non-mathematical, descriptive and graphical way along with the story of the telescopes. Emphasis is placed on the interplay between astronomical and electromagnetic requirements and structural, mechanical and control solutions. A chapter on management aspects of large telescope projects closes the book. The authors address a readership with interest in the progress of engineering sol...

Antenna theory: Analysis and design

Science.gov (United States)

Balanis, C. A.

The book's main objective is to introduce the fundamental principles of antenna theory and to apply them to the analysis, design, and measurements of antennas. In a description of antennas, the radiation mechanism is discussed along with the current distribution on a thin wire. Fundamental parameters of antennas are examined, taking into account the radiation pattern, radiation power density, radiation intensity, directivity, numerical techniques, gain, antenna efficiency, half-power beamwidth, beam efficiency, bandwidth, polarization, input impedance, and antenna temperature. Attention is given to radiation integrals and auxiliary potential functions, linear wire antennas, loop antennas, linear and circular arrays, self- and mutual impedances of linear elements and arrays, broadband dipoles and matching techniques, traveling wave and broadband antennas, frequency independent antennas and antenna miniaturization, the geometrical theory of diffraction, horns, reflectors and lens antennas, antenna synthesis and continuous sources, and antenna measurements.

Influence of surface error on electromagnetic performance of reflectors based on Zernike polynomials

Science.gov (United States)

Li, Tuanjie; Shi, Jiachen; Tang, Yaqiong

2018-04-01

This paper investigates the influence of surface error distribution on the electromagnetic performance of antennas. The normalized Zernike polynomials are used to describe a smooth and continuous deformation surface. Based on the geometrical optics and piecewise linear fitting method, the electrical performance of reflector described by the Zernike polynomials is derived to reveal the relationship between surface error distribution and electromagnetic performance. Then the relation database between surface figure and electric performance is built for ideal and deformed surfaces to realize rapidly calculation of far-field electric performances. The simulation analysis of the influence of Zernike polynomials on the electrical properties for the axis-symmetrical reflector with the axial mode helical antenna as feed is further conducted to verify the correctness of the proposed method. Finally, the influence rules of surface error distribution on electromagnetic performance are summarized. The simulation results show that some terms of Zernike polynomials may decrease the amplitude of main lobe of antenna pattern, and some may reduce the pointing accuracy. This work extracts a new concept for reflector's shape adjustment in manufacturing process.

Total focusing method with correlation processing of antenna array signals

Science.gov (United States)

Kozhemyak, O. A.; Bortalevich, S. I.; Loginov, E. L.; Shinyakov, Y. A.; Sukhorukov, M. P.

2018-03-01

The article proposes a method of preliminary correlation processing of a complete set of antenna array signals used in the image reconstruction algorithm. The results of experimental studies of 3D reconstruction of various reflectors using and without correlation processing are presented in the article. Software ‘IDealSystem3D’ by IDeal-Technologies was used for experiments. Copper wires of different diameters located in a water bath were used as a reflector. The use of correlation processing makes it possible to obtain more accurate reconstruction of the image of the reflectors and to increase the signal-to-noise ratio. The experimental results were processed using an original program. This program allows varying the parameters of the antenna array and sampling frequency.

A Simple Ultra-Wideband Magneto-Electric Dipole Antenna With High Gain

Science.gov (United States)

Shuai, Chen-yang; Wang, Guang-ming

2017-12-01

A simple ultra-wideband magneto-electric dipole antenna utilizing a differential-fed structure is designed. The antenna mainly comprises three parts, including a novel circular horned reflector, two vertical semicircular shorted patches as a magnetic dipole, and a horizontal U-shaped semicircular electric dipole. A differential feeding structure working as a perfect balun excites the designed antenna. The results of simulation have a good match with the ones of measurement. Results indicate that the designed antenna achieves a wide frequency bandwidth of 107 % which is 3.19 10.61 GHz, when VSWR is below 2. Via introducing the circular horned reflector, the designed antenna attains a steady and high gain of 12±1.5dBi. Moreover, settled broadside direction main beam, high front-to-back ratio, low cross polarization, and the symmetrical and relatively stable radiation patterns in the E-and H-plane are gotten in the impedance bandwidth range. In the practical applications, the proposed antenna that is dc grounded and has a simple structure satisfies the requirement of many outdoor antennas.

Microwave antenna holography

Science.gov (United States)

Rochblatt, David J.; Seidel, Boris L.

1992-01-01

This microwave holography technique utilizes the Fourier transform relation between the complex far field radiation pattern of an antenna and the complex aperture field distribution. Resulting aperture phase and amplitude distribution data can be used to precisely characterize various crucial performance parameters, including panel alignment, panel shaping, subreflector position, antenna aperture illumination, directivity at various frequencies, and gravity deformation effects. The methodology of data processing presented here was successfully applied to the Deep Space Network (DSN) 34-m beam waveguide antennas. The antenna performance was improved at all operating frequencies by reducing the main reflector mechanical surface rms error to 0.43 mm. At Ka-band (32 GHz), the estimated improvement is 4.1 dB, resulting in an aperture efficiency of 52 percent. The performance improvement was verified by efficiency measurements and additional holographic measurements.

Geological signatures of drillhole radar reflectors in ONKALO

International Nuclear Information System (INIS)

Doese, C.; Gustafsson, J.

2011-12-01

The geological signatures of radar reflectors in ONKALO have been evaluated as a subactivity within the Joint Work Programme 'Rock Suitability Criteria' strategies and methodology' between Svensk Kaernbraenslehantering AB and Posiva Oy. In addition to the geological signature, the usage of geophysical data to predict large fractures was evaluated. Pilot hole radar loggings were carried out using a RAMAC GPR-250 MHz dipole antenna. The radar data were evaluated and reflectors with known position and intersection angle to the pilot hole were correlated with fractures or foliation in the pilot hole and with Tunnel Crosscutting Fractures in the tunnel. This data served as in-data for the evaluation of the geological signatures of radar reflectors. The result of the evaluation is not univocal. Half of the reflectors could be explained by fractures in the pilot hole, but only about 10 % of the reflectors can be explained by Tunnel Crosscutting Fractures. Of these 10 %, 2/3 can also be explained by foliation, leaving only some 3 % of the total reflectors more unambiguously correlated with Tunnel Crosscutting Fractures. The fractures correlated with radar reflectors do not diverge much from other fractures. Fractures having intersection angles of 30 deg- 60 deg are more likely to be detected by radar relative to other. Other properties that seem to be overrepresented in fractures correlated with radar reflectors are quartz and/or graphite content, width ≥0.8 mm and higher alteration (J a ≥3), but the data is not unambiguous. (orig.)

Application of Ruze Equation for Inflatable Aperture Antennas

Science.gov (United States)

Welch, Bryan W.

2008-01-01

Inflatable aperture reflector antennas are an emerging technology that NASA is investigating for potential uses in science and exploration missions. As inflatable aperture antennas have not been proven fully qualified for space missions, they must be characterized properly so that the behavior of the antennas can be known in advance. To properly characterize the inflatable aperture antenna, testing must be performed in a relevant environment, such as a vacuum chamber. Since the capability of having a radiofrequency (RF) test facility inside a vacuum chamber did not exist at NASA Glenn Research Center, a different methodology had to be utilized. The proposal to test an inflatable aperture antenna in a vacuum chamber entailed performing a photogrammetry study of the antenna surface by using laser ranging measurements. A root-mean-square (rms) error term was derived from the photogrammetry study to calculate the antenna surface loss as described by the Ruze equation. However, initial testing showed that problems existed in using the Ruze equation to calculate the loss due to errors on the antenna surface. This study utilized RF measurements obtained in a near-field antenna range and photogrammetry data taken from a laser range scanner to compare the expected performance of the test antenna (via the Ruze equation) with the actual RF patterns and directivity measurements. Results showed that the Ruze equation overstated the degradation in the directivity calculation. Therefore, when the photogrammetry study is performed on the test antennas in the vacuum chamber, a more complex equation must be used in light of the fact that the Ruze theory overstates the loss in directivity for inflatable aperture reflector antennas.

A smart car for the surface shape measurement of large antenna based on laser tracker

Science.gov (United States)

Gu, Yonggang; Hu, Jing; Jin, Yi; Zhai, Chao

2012-09-01

The geometric accuracy of the surface shape of large antenna is an important indicator of antenna’s quality. Currently, high-precision measurement of large antenna surface shape can be performed in two ways: photogrammetry and laser tracker. Photogrammetry is a rapid method, but its accuracy is not enough good. Laser tracker can achieve high precision, but it is very inconvenient to move the reflector (target mirror) on the surface of the antenna by hand during the measurement. So, a smart car is designed to carry the reflector in this paper. The car, controlled by wireless, has a small weight and a strong ability for climbing, and there is a holding bracket gripping the reflector and controlling reflector rise up and drop down on the car. During the measurement of laser tracker, the laser beam between laser tracker and the reflector must not be interrupted, so two high-precision three-dimensional miniature electronic compasses, which can real-time monitor the relative angle between the holding bracket and the laser tracker’s head, are both equipped on the car and the head of laser tracker to achieve automatic alignment between reflector and laser beam. With the aid of the smart car, the measurement of laser tracker has the advantages of high precision and rapidity.

Shape control of slack space reflectors using modulated solar pressure.

Science.gov (United States)

Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R

2015-07-08

The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes.

Testing of the BipiColombo Antenna Pointing Mechanism

Science.gov (United States)

Campo, Pablo; Barrio, Aingeru; Martin, Fernando

2015-09-01

BepiColombo is an ESA mission to Mercury, its planetary orbiter (MPO) has two antenna pointing mechanism, High gain antenna (HGA) pointing mechanism steers and points a large reflector which is integrated at system level by TAS-I Rome. Medium gain antenna (MGA) APM points a 1.5 m boom with a horn antenna. Both radiating elements are exposed to sun fluxes as high as 10 solar constants without protections.A previous paper [1] described the design and development process to solve the challenges of performing in harsh environment.. Current paper is focused on the testing process of the qualification units. Testing performance of antenna pointing mechanism in its specific environmental conditions has required special set-up and techniques. The process has provided valuable feedback on the design and the testing methods which have been included in the PFM design and tests.Some of the technologies and components were developed on dedicated items priort to EQM, but once integrated, test behaviour had relevant differences.Some of the major concerns for the APM testing are:- Create during the thermal vacuum testing the qualification temperature map with gradients along the APM. From of 200oC to 70oC.- Test in that conditions the radio frequency and pointing performances adding also high RF power to check the power handling and self-heating of the rotary joint.- Test in life up to 12000 equivalent APM revolutions, that is 14.3 million motor revolutions in different thermal conditions.- Measure low thermal distortion of the mechanical chain, being at the same time insulated from external environment and interfaces (55 arcsec pointing error)- Perform deployment of large items guaranteeing during the process low humidity, below 5% to protect dry lubrication- Verify stability with representative inertia of large boom or reflector 20 Kgm2.

Frequency Selective Surfaces for extended Bandwidth backing reflector functions

NARCIS (Netherlands)

Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

2008-01-01

This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

Development of a High Temperature Antenna Pointing Mechanism for BepiColombo Planetary Orbiter

Science.gov (United States)

Campo, Pablo; Barrio, Aingeru; Puente, Nicolas; Kyle, Robert

2013-09-01

BepiColombo is an ESA mission to Mercury its planetary orbiter (MPO) has two antenna pointing mechanism, High gain antenna pointing mechanism steers and points a large reflector which is integrated at system level by TAS-I Rome. Medium gain antenna (MGA) APM points a 1.5 m boom with a horn antenna. Both radiating elements exposed to sun fluxes as high as 10 solar constants without protections.The pointing mechanism is a major challenge as high performances are required in a harsh environment. It has required the development of new technologies, and components specially dedicated for the mission needs. Some of the state of the art required for the mission was achieved during the preparatory technology development activities [1]. However the number of critical elements involved, and the difficulties of some areas have required the continuation of the developments, and new research activities had to be launched in CD phase. Some of the major concerns and related areas of development are:- High temperature and long life requirements for the gearhead motors (up to 15500 equivalent APM revolutions, 19 million motor revolution)- Low thermal distortion of the mechanical chain, being at the same time insulating from external environment and interfaces (55 arcsec pointing error)- Low heat leak to the spacecraft (in the order of 50W per APM)- High precision position control, low microvibration noise and error stability in motion (16 arcsec/s)- High power radio frequency (18W in band Ka, 30 in X band) with phase stability for use in radio-science (3mm in Ka band, 5o in X band).- Wide range of motion (full 360o with end-stops)Currently HGA APM EQM azimuth and elevation stages are assembled and ready for test at actuator level.

Subreflector extension for improved efficiencies in Cassegrain antennas - GTD/PO analysis. [Geometrical Theory of Diffraction/Physical Optics

Science.gov (United States)

Rahmat-Samii, Yahya

1986-01-01

Both offset and symmetric Cassegrain reflector antennas are used in satellite and ground communication systems. It is known that the subreflector diffraction can degrade the performance of these reflectors. A geometrical theory of diffraction/physical optics analysis technique is used to investigate the effects of the extended subreflector, beyond its optical rim, on the reflector efficiency and far-field patterns. Representative numerical results are shown for an offset Cassegrain reflector antenna with different feed illumination tapers and subreflector extensions. It is observed that for subreflector extensions as small as one wavelength, noticeable improvements in the overall efficiencies can be expected. Useful design data are generated for the efficiency curves and far-field patterns.

Implementasi Reflector Antena Wajanbolik Pada Layanan EVDO (Evolution Data Optimized

Directory of Open Access Journals (Sweden)

BIMA BIMA

2017-06-01

Full Text Available Abstrak Antena merupakan perangkat yang memiliki peranan yang sangat penting dalam sistem komunikasi tanpa kabel (wireless. Pada penelitian ini akan diimplementasikan reflektor antena wajanbolik yang beroperasi pada frekuensi CDMA 2000 1x EVDO 1900 MHz. Antena ini menggunakan  reflektor dari wajan, dengan waveguide dari pipa paralon yang dilapisi dengan lakban alumunium, dan penerima sinyal menggunakan USB modem adapter. Antena ini ditujukan untuk menjadi media bantu  dalam  memperkuat  penerimaan sinyal  EVDO dan memaksimalkan dan kecepatan transfer data. Antena ini memberikan gain sebesar 15,530 dB berdasarkan pengukuran dan 15,156 dB berdasarkan teoritis. Pengujian menggunakan wajanbolik menunjukkan adanya peningkatan level sinyal modem yang terendah sebesar 4 dB pada pengukuran dengan kondisi indoor di siang hari serta tertinggi sebesar 19 dB pada pengukuran dengan kondisi outdoor di malam hari. Hasil dari pengujian pun menunjukkan peningkatan kecepatan transfer data rata – rata sebesar 42 KBps sampai dengan 269 KBps dibandingkan pengukuran tanpa wajanbolik.   Kata kunci: Reflektor, Waveguide, Wajanbolik, USB adapter, EVDO.    Abstract   The antenna is a device that has a very important role in wireless communication systems (wireless. In this research will be implemented wajanbolik reflector antenna which operates at frequencies of CDMA 2000 1x EVDO 1900 MHz. This antenna uses a reflector of the pan, with the waveguide of the pipe is coated with aluminum duct tape, and a signal receiver using a USB modem adapter. This antenna is intended to be a media aids in strengthening the EVDO and signal reception to maximize data transfer speeds. This antenna give a gain of 16.015 from measurement dBi and 15.156 dBi based on theory. Tests using wajanbolik showed an increase in the level of modem signals a low of 4 dB in measurement with indoor conditions during the day and 19 dB at the peak of measurements with outdoor conditions at night

Study of Membrane Reflector Technology

Science.gov (United States)

Knapp, K.; Hedgepeth, J.

1979-01-01

Very large reflective surfaces are required by future spacecraft for such purposes as solar energy collection, antenna surfaces, thermal control, attitude and orbit control with solar pressure, and solar sailing. The performance benefits in large membrane reflector systems, which may be derived from an advancement of this film and related structures technology, are identified and qualified. The results of the study are reported and summarized. Detailed technical discussions of various aspects of the study are included in several separate technical notes which are referenced.

A nonlinear equivalent circuit method for analysis of passive intermodulation of mesh reflectors

Directory of Open Access Journals (Sweden)

Jiang Jie

2014-08-01

Full Text Available Passive intermodulation (PIM has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal (MM contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.

A Microfabricated 8-40 GHz Dual-Polarized Reflector Feed

Science.gov (United States)

Vanhille, Kenneth; Durham, Tim; Stacy, William; Karasiewicz, David; Caba, Aaron; Trent, Christopher; Lambert, Kevin; Miranda, Felix

2014-01-01

Planar antennas based on tightly coupled dipole arrays (also known as a current sheet antenna or CSA) are amenable for use as electronically scanned phased arrays. They are capable of performance nearing a decade of bandwidth. These antennas have been demonstrated in many implementations at frequencies below 18 GHz. This paper describes the implementation using a relatively new multi-layer microfabrication process resulting in a small, 6x6 element, dual-linear polarized array with beamformer that operates from 8 to 40 GHz. The beamformer includes baluns that feed the dual-polarized differential antenna elements and reactive splitter networks that also cover the full frequency range of operation. This antenna array serves as a reflector feed for a multi-band instrument designed to measure snow water equivalent (SWE) from airborne platforms. The instrument has both radar and radiome try capability at multiple frequencies. Scattering-parameter and time-domain measurements have been used to characterize the array feed. Radiation patterns of the antenna have been measured and are compared to simulation. To the best of the authors' knowledge, this work represents the most integrated multi-octave millimeter-wave antenna feed fabricated to date.

DSN Microwave Antenna Holography

Science.gov (United States)

Rochblatt, D. J.; Seidel, B. L.

1984-01-01

The DSN microwave antenna holography project will obtain three-dimensional pictures of the large DSN antenna surfaces. These pictures must be of suffi icient resolution to allow adjustment of the reflector panels to an rms surface of 0.5 mm (0.25 mm, goal). The major parameters and equations needed to define a holographic measurement system are outlined and then the proof of concept demonstration measurement that was made at DSS-43 (Australia) that resulted in contour maps with spatial resolution of 7 m in the aperture plane and resolution orthogonal to the aperture plane of 0.7 mm was discussed.

Some Recent Developments of Microstrip Antenna

Directory of Open Access Journals (Sweden)

Yong Liu

2012-01-01

Full Text Available Although the microstrip antenna has been extensively studied in the past few decades as one of the standard planar antennas, it still has a huge potential for further developments. The paper suggests three areas for further research based on our previous works on microstrip antenna elements and arrays. One is exploring the variety of microstrip antenna topologies to meet the desired requirement such as ultrawide band (UWB, high gain, miniaturization, circular polarization, multipolarized, and so on. Another is to apply microstrip antenna to form composite antenna which is more potent than the individual antenna. The last is growing towards highly integration of antenna/array and feeding network or operating at relatively high frequencies, like sub-millimeter wave or terahertz (THz wave regime, by using the advanced machining techniques. To support our points of view, some examples of antennas developed in our group are presented and discussed.

Low Radar Cross-section and Low Cost Dipole Antenna Reflector

Directory of Open Access Journals (Sweden)

G. G. Machado

2017-10-01

Full Text Available This paper presents a method for reducing Radar CrossSection (RCS of an increased gain metal backed dipole antenna. Numerical simulations were done and compared to a laboratory experiment. The results show that when a Perfect Electrical Conductor (PEC is replaced by a Frequency Selective Surface (FSS, the antenna is still able to perform with the desired characteristics, but the RCS of the structure is greatly reduced out of band. The design of the FSS and the return loss, gain improvement, and RCS are presented for an antenna operating at 4.2GHz, and the results are compared with a conventional metal backed layout. Measurements show a good agreement with the simulations, and so the advantages on other structures from the reviewed literature are mentioned.

Structural Design of the DTU-ESA MM-Wave Validation Standard Antenna

DEFF Research Database (Denmark)

Branner, Kim; Berring, Peter; Markussen, Christen Malte

2015-01-01

A new specially designed antenna to be used for inter-comparisons and validation of antenna test facilities is under development in cooperation between DTU and TICRA under a contract from the European Space Agency. The antenna is designed to be extremely thermally and mechanically stable...... in the range of temperatures 20±5°C under arbitrary orientation in the gravity field. The antenna has a characteristic length of approximately 500mm. And in order to obtain very low measuring error, the allowable deformations of the reflector and feeds are down to 2.5μm. The antenna is modelled structurally...... is connected via a glued contact formulation in MSC.MARC. Because of the size and the complexity of the model a computer cluster is applied to solve the analyses. This paper describes the structural solution to meet these extremely strict stability requirements and the structural analyses done in order...

The ExaVolt Antenna: Concept and Development Updates

Directory of Open Access Journals (Sweden)

Pfendner Carl

2017-01-01

Full Text Available A flux of ultrahigh energy neutrinos is expected both directly from sources and from interactions between ultrahigh energy cosmic rays and the cosmic microwave background. Using the cost-effective radio Cherenkov technique to search for these neutrinos, the ExaVolt Antenna (EVA is a mission concept that aims to build on the capabilities of earlier radio-based balloon-borne neutrino detectors and increase the sensitivity to lower energies and fluxes. The novel EVA design exploits the surface of the balloon to provide a focusing reflector that aims to provide a signal gain of ~ 30 dBi (compared to 10 dBi on ANITA. This increase in gain when combined with a large instantaneous viewing angle will yield a 10-fold increase in sensitivity and will allow this balloon-borne experiment to probe the expected low neutrino fluxes even at energies greater than 1019 eV. This contribution will present an overview of the mission concept, recent technology developments, and the results of a hang test of a 1:20-scale model which demonstrates the effectiveness of the design.

Optically Controlled Reconfigurable Antenna Array Based on E-Shaped Elements

Directory of Open Access Journals (Sweden)

Arismar Cerqueira Sodré Junior

2014-01-01

Full Text Available This work presents the development of optically controlled reconfigurable antenna arrays. They are based on two patch elements with E-shaped slots, a printed probe, and a photoconductive switch made from an intrinsic silicon die. Numerical simulations and experiments have been shown to be in agreement, and both demonstrate that the frequency response of the antenna arrays can be efficiently reconfigured over two different frequency ISM bands, namely, 2.4 and 5 GHz. A measured gain of 12.5 dBi has been obtained through the use of two radiating elements printed in a low-cost substrate and a dihedral corner reflector.

Photogrammetry Of A Parabolic Antenna

Science.gov (United States)

Merrick, W. D.; Lansing, F. L.; Stoller, F. W.; Lobb, V. B.

1988-01-01

Surface measured with accuracy better than 10 to the negative fifth power times diameter. Report describes use of advanced close-range photogrammetry to determine deviations of 34-m-diameter antenna main reflector and subreflector from nominal paraboloidal shapes. Measurements enable removal of linear offsets and angular misalignments of subreflector, with consequent increase of 4 percent in aperture efficiency.

Development of a New core/reflector model for coarse-mesh nodal methods

International Nuclear Information System (INIS)

Pogosbekyan, Leonid; Cho, Jin Young; Kim, Young Il; Kim, Young Jin; Joo, Hyung Kuk; Chang, Moon Hee.

1997-10-01

This work presents two approaches for reflector simulation in coarse-mesh nodal methods. The first approach is called Interface Matrix Technique (IMT), which simulates the baffle as a banishingly thin layer having the property of reflection and transmission. We applied this technique within the frame of AFEN (Analytic Function Expansion Nodal) method, and developed the AFEN-IM (Interface Matrix) method. AFEN-IM method shows 1.24% and 0.42 % in maximum and RMS (Root Mean Square) assemblywise power error for ZION-1 benchmark problem. The second approach is L-shaped reflector homogenization method. This method is based on the integral response conservation along the L-shaped core-reflector interface. The reference reflector response is calculated from 2-dimensional spectral calculation and the response of the homogenized reflector is derived from the one-node 2-dimensional AFEN problem solution. This method shows 5 times better accuracy than the 1-dimensional homogenization technique in the assemblywise power. Also, the concept of shroud/reflector homogenization for hexagonal core have been developed. The 1-dimensional spectral calculation was used for the determination of 2 group cross sections. The essence of homogenization concept consists in the calculation of equivalent shroud width, which preserve albedo for the fast neutrons in 2-dimensional reflector. This method shows a relative error less than 0.42% in assemblywise power and a difference of 9x10 -5 in multiplication factor for full-core model. (author). 9 refs., 3 tabs., 28 figs

Performance Investigations of Quasi-Yagi Loop and Dipole Antennas on Silicon Substrate for 94 GHz Applications

Directory of Open Access Journals (Sweden)

Osama M. Haraz

2014-01-01

Full Text Available This paper introduces the design and implementation of two high gain Quasi-Yagi printed antennas developed on silicon substrate for 94 GHz imaging applications. The proposed antennas are based on either driven loop or dipole antennas fed by a coplanar waveguide (CPW feeding structure. For better matching with the driven antennas, a matching section has been added between the CPW feedline and the driven antenna element. To improve the gain of either loop or dipole antennas, a ground reflector and parasitic director elements have been added. Two Quasi-Yagi antenna prototypes based on loop and dipole antenna elements have been fabricated and experimentally tested using W-band probing station (75–110 GHz. The measured results show good agreement with simulated results and confirm that the proposed antennas are working. In addition, a feed and matching configuration is proposed to enable coupling a microbolometer element to the proposed Quasi-Yagi antenna designs for performing radiation pattern measurements.

Borehole radar directionality in the time domain in small aperture antennas

CSIR Research Space (South Africa)

Vogt, DR

2008-06-01

Full Text Available by interpolation. Initial tests show that mutual coupling between the antenna elements does affect the relative timing, but does not prevent the extraction of usable directional data. Experimental data from a test tank confirms that estimates of reflector... the phase differ- ences at each antenna. They showed that mutual cou- pling was tolerable. In a related paper [9] they presented an algorithm to recover direction that performed well. II. SYSTEM DESCRIPTION In this paper, a directional antenna...

A Static Displacement Monitoring System for VLBI Antenna Using Close-Range Photogrammetry

Directory of Open Access Journals (Sweden)

Hyukgil Kim

2017-11-01

Full Text Available In this study, a static displacement monitoring program was developed to maintain the accurate performance of a Very Long Baseline Interferometry (VLBI antenna by monitoring its structural stability. The monitoring program was designed to measure static displacement, among the many displacements of the antenna’s main reflector, which can directly affect its performance. The program measures the position of a monitored object with mm-level accuracy through close-range photogrammetry that uses high-resolution Charge Coupled Device (CCD cameras. The developed program will be used to evaluate the structural soundness of an antenna based on continuous displacement measurements, which can also be used as basic data for repair and reinforcement work in the future.

Development of an environment-insensitive PWR radial reflector model applicable to modern nodal reactor analysis method

International Nuclear Information System (INIS)

Mueller, E.M.

1989-05-01

This research is concerned with the development and analysis of methods for generating equivalent nodal diffusion parameters for the radial reflector of a PWR. The requirement that the equivalent reflector data be insensitive to changing core conditions is set as a principle objective. Hence, the environment dependence of the currently most reputable nodal reflector models, almost all of which are based on the nodal equivalence theory homgenization methods of Koebke and Smith, is investigated in detail. For this purpose, a special 1-D nodal equivalence theory reflector model, called the NGET model, is developed and used in 1-D and 2-D numerical experiments. The results demonstrate that these modern radial reflector models exhibit sufficient sensitivity to core conditions to warrant the development of alternative models. A new 1-D nodal reflector model, which is based on a novel combination of the nodal equivalence theory and the response matrix homogenization methods, is developed. Numerical results varify that this homogenized baffle/reflector model, which is called the NGET-RM model, is highly insensitive to changing core conditions. It is also shown that the NGET-RM model is not inferior to any of the existing 1-D nodal reflector models and that it has features which makes it an attractive alternative model for multi-dimensional reactor analysis. 61 refs., 40 figs., 36 tabs

New Modelling Capabilities in Commercial Software for High-Gain Antennas

DEFF Research Database (Denmark)

Jørgensen, Erik; Lumholt, Michael; Meincke, Peter

2012-01-01

characterization of the reflectarray element, an initial phaseonly synthesis, followed by a full optimization procedure taking into account the near-field from the feed and the finite extent of the array. Another interesting new modelling capability is made available through the DIATOOL software, which is a new...... type of EM software tool aimed at extending the ways engineers can use antenna measurements in the antenna design process. The tool allows reconstruction of currents and near fields on a 3D surface conformal to the antenna, by using the measured antenna field as input. The currents on the antenna...... surface can provide valuable information about the antenna performance or undesired contributions, e.g. currents on a cable,can be artificially removed. Finally, the CHAMP software will be extended to cover reflector shaping and more complex materials,which combined with a much faster execution speed...

Maximum super angle optimization method for array antenna pattern synthesis

DEFF Research Database (Denmark)

Wu, Ji; Roederer, A. G

1991-01-01

Different optimization criteria related to antenna pattern synthesis are discussed. Based on the maximum criteria and vector space representation, a simple and efficient optimization method is presented for array and array fed reflector power pattern synthesis. A sector pattern synthesized by a 2...

SKB - PNC. Development of tunnel radar antennas

International Nuclear Information System (INIS)

Falk, L.

1991-07-01

Tunnel antennas for the RAMAC borehole radar system have been developed and tested in the field. The antennas are of the loaded dipole type and the receiver and transmitter electronics have been rebuilt to screen them from the antennas. A series of measurements has demonstrated that the radar pulse is short and well shaped and relatively free from ringing, even compared with the existing borehole antennas. Two antenna sets were tested: one centered at 60 MHz and another above 100 MHz. Both produced excellent radar pictures when tested in tunnels in Stripa mine. The antennas have been designed to be easy to carry, since the signal quality often depends on the way the antenna is held relative to electric conductors in the tunnels. (au) (46 figs., 57 refs.)

Development of an innovative reflector drive mechanism using magnetic repulsion force for 4S reactor

International Nuclear Information System (INIS)

Tsuji, K.; Watanabe, M.; Inagaki, H.; Nishikawa, A.; Takahashi, H.; Wakamatsu, M.; Matsumiya, H.; Nishiguchi, Y.

2001-01-01

A small sized fast reactor 4S: (Super Safe Small and Simple) which has a core of 10 - 30 years life time is controlled by reflectors. The reflector is required to be risen at very low speed to make up for the reactivity swing during operation. This report shows the development of an innovative reflector drive mechanism using magnetic repulsion force that can move at a several micrometer per one step. This drive mechanism has a passive shut down capability, and can eliminate reflector drive line. (author)

Antenna Design for Directivity-Enhanced Raman Spectroscopy

Directory of Open Access Journals (Sweden)

Aftab Ahmed

2012-01-01

Full Text Available Antenna performance can be described by two fundamental parameters: directivity and radiation efficiency. Here, we demonstrate nanoantenna designs in terms of improved directivity. Performance of the antennas is demonstrated in Raman scattering experiments. The radiated beam is directed out of the plane by using a ground plane reflector for easy integration with commercial microscopes. Parasitic elements and parabolic and waveguide nanoantennas with a ground plane are explored. The nanoantennas were fabricated by a series of electron beam evaporation steps and focused ion beam milling. As we have shown previously, the circular waveguide nanoantenna boosts the measured Raman signal by 5.5x with respect to a dipole antenna over a ground plane; here, we present the design process that led to the development of that circular waveguide nanoantenna. This work also shows that the parabolic nanoantenna produces a further fourfold improvement in the measured Raman signal with respect to a circular waveguide nanoantenna. The present designs are nearly optimal in the sense that almost all the beam power is coupled into the numerical aperture of the microscope. These designs can find applications in microscopy, spectroscopy, light-emitting devices, photovoltaics, single-photon sources, and sensing.

Development of corotational formulated FEM for application to 30m class large deployable reflector

International Nuclear Information System (INIS)

Ozawa, Satoru; Fujiwara, Yuuichi; Tsujihata, Akio

2010-01-01

JAXA, Japan Aerospace Exploration Agency, is now developing a corotational formulated finite element analysis method and its software 'Origami/ETS' for the development of 30m class large deployable reflectors. For the reason that the deployable reflector is composed of beams, cables and mesh, this analysis method is generalized for finite elements with multiple nodes, which are commonly used in linear finite element analyses. The large displacement and rotation are taken into account by the corotational formulation. The tangent stiffness matrix for finite elements with multiple nodes is obtained as follows; the geometric stiffness matrix of two node elements is derived by taking variation of the element's corotational matrix from the virtual work of finite elements with large displacement; similarly the geometric stiffness matrix for three node elements is derived; as the extension of two and three node element theories, the geometric stiffness matrix for multiple node elements is derived; with the geometric stiffness matrix for multiple node elements, the tangent stiffness matrix is obtained. The analysis method is applied for the deployment analysis and static structural analysis of the 30m class large deployable reflector. In the deployment analysis, it is confirmed that this method stably analyzes the deployment motion from the deployment configuration to the stowed configuration of the reflector. In the static analysis, it is confirmed that the mesh structure is analyzed successfully. The 30m class large deployable reflector is now still being developed and is about to undergo several tests with its prototypes. This analysis method will be used in the tests and verifications of the reflector.

Development of Ray Tracing Algorithms for Scanning Plane and Transverse Plane Analysis for Satellite Multibeam Application

Directory of Open Access Journals (Sweden)

N. H. Abd Rahman

2014-01-01

Full Text Available Reflector antennas have been widely used in many areas. In the implementation of parabolic reflector antenna for broadcasting satellite applications, it is essential for the spacecraft antenna to provide precise contoured beam to effectively serve the required region. For this purpose, combinations of more than one beam are required. Therefore, a tool utilizing ray tracing method is developed to calculate precise off-axis beams for multibeam antenna system. In the multibeam system, each beam will be fed from different feed positions to allow the main beam to be radiated at the exact direction on the coverage area. Thus, detailed study on caustics of a parabolic reflector antenna is performed and presented in this paper, which is to investigate the behaviour of the rays and its relation to various antenna parameters. In order to produce accurate data for the analysis, the caustic behaviours are investigated in two distinctive modes: scanning plane and transverse plane. This paper presents the detailed discussions on the derivation of the ray tracing algorithms, the establishment of the equations of caustic loci, and the verification of the method through calculation of radiation pattern.

PROSPECTS FOR THE DEVELOPMENT OF PHASED ANTENNA ARRAYS

Directory of Open Access Journals (Sweden)

A. P. Dzuba

2013-01-01

Full Text Available This article describes the main achievements in the development of phased antenna arrays (par in the past decade. Provides an overview of the most famous systems based on the PAR and PAR based on MMIC technology - PAR in radar stations, PAR to control the laser and optical beams. The existing options for the design of the PAR:ferroelectric antenna array; plasma antenna with electronic scanning; reflective grating on 100-mm semiconductor wafers; wideband antenna arrays with aperture; antenna arrays with digital beam forming.

An Optimal Beamforming Algorithm for Phased-Array Antennas Used in Multi-Beam Spaceborne Radiometers

DEFF Research Database (Denmark)

Iupikov, O. A.; Ivashina, M. V.; Pontoppidan, K.

2015-01-01

Strict requirements for future spaceborne ocean missions using multi-beam radiometers call for new antenna technologies, such as digital beamforming phased arrays. In this paper, we present an optimal beamforming algorithm for phased-array antenna systems designed to operate as focal plane arrays...... to a FPA feeding a torus reflector antenna (designed under the contract with the European Space Agency) and tested for multiple beams. The results demonstrate an improved performance in terms of the optimized beam characteristics, yielding much higher spatial and radiometric resolution as well as much...

Reconfigurable Magneto-Electric Dipole Antennas for Base Stations in Modern Wireless Communication Systems

Directory of Open Access Journals (Sweden)

Lei Ge

2018-01-01

Full Text Available Magneto-electric (ME dipole antennas, with the function of changing the antenna characteristics, such as frequency, polarization, or radiation patterns, are reviewed in this paper. The reconfigurability is achieved by electrically altering the states of diodes or varactors to change the surface currents distributions or reflector size of the antenna. The purpose of the designs is to obtain agile antenna characteristics together with good directive radiation performances, such as low cross-polarization level, high front-to-back ratio, and stable gain. By reconfiguring the antenna capability to support more than one wireless frequency standard, switchable polarizations, or cover tunable areas, the reconfigurable ME dipole antennas are able to switch functionality as the mission changes. Therefore, it can help increase the communication efficiency and reduce the construction cost. This shows very attractive features in base station antennas of modern wireless communication applications.

Recent developments in ICRF antenna modelling

International Nuclear Information System (INIS)

Lamalle, P.U.; Messiaen, A.M.; Dumortier, P.; Louche, F.

2005-01-01

The antennas presently developed for ICRF heating of the ITER plasma consist of a tightly packed array of a large number of radiating straps, in order to deliver a high power density without exceeding radio-frequency voltage standoffs. Recently developed commercial software has enabled important progress in the coupling analysis and optimisation of such demanding systems. Approximations allowing to convincingly include a realistic plasma description in these codes are discussed. Application of the resulting numerical tools is illustrated by simulation of the existing JET A2 ICRF array, with the goal to validate simulations for future antennas. Advances in the design of realistic test bed conditions, using salted water as a means of creating plasma-relevant antenna loading, and the appropriate scaling of a mockup are also presented. (author)

Antenna development for astroparticle and radioastronomy experiments

Energy Technology Data Exchange (ETDEWEB)

Charrier, Didier, E-mail: charrier@emn.fr [Subatech, Ecole des Mines de Nantes - CNRS/IN2P3 - Universite de Nantes (France)

2012-01-11

An active dipole antenna is in operation since five years at the Nancay radio Observatory (France) in the CODALEMA experiment. A new version of this active antenna has been developed, whose shape gave its name of 'Butterfly' antenna. Compared to the previous version, this new antenna has been designed to be more efficient at low frequencies, which could permit the detection of atmospheric showers at large distances. Despite a size of only 2 m Multiplication-Sign 1 m in each polarization, its sensitivity is excellent in the 30-80 MHz bandwidth. Three antennas in dual polarization were installed on the CODALEMA experiment, and four other have been recently installed on the Auger area in the scope of the AERA project. The main characteristics of the Butterfly antenna are detailed with an emphasis on its key features which make it a good candidate for the low frequency radioastronomy and the radio detection of transients induced by high energy cosmic rays.

Antenna development for astroparticle and radioastronomy experiments

International Nuclear Information System (INIS)

Charrier, Didier

2012-01-01

An active dipole antenna is in operation since five years at the Nançay radio Observatory (France) in the CODALEMA experiment. A new version of this active antenna has been developed, whose shape gave its name of “Butterfly” antenna. Compared to the previous version, this new antenna has been designed to be more efficient at low frequencies, which could permit the detection of atmospheric showers at large distances. Despite a size of only 2 m×1 m in each polarization, its sensitivity is excellent in the 30-80 MHz bandwidth. Three antennas in dual polarization were installed on the CODALEMA experiment, and four other have been recently installed on the Auger area in the scope of the AERA project. The main characteristics of the Butterfly antenna are detailed with an emphasis on its key features which make it a good candidate for the low frequency radioastronomy and the radio detection of transients induced by high energy cosmic rays.

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).

Resonant double loop antenna development at ORNL

International Nuclear Information System (INIS)

Taylor, D.J.; Baity, F.W.; Brown, R.A.; Bryan, W.E.; Fadnek, A.; Hoffman, D.J.; King, J.F.; Livesey, R.L.; McIlwain, R.L.

1988-01-01

As part of the development of ion cyclotron resonant heating (ICRH) systems for fusion research, Oak Ridge National Laboratory (ORNL) has built resonant double loop (RDL) antennas for the Tokamak Fusion Test Reactor (TFTR) (Princeton Plasma Physics Laboratory, Princeton, NJ, US) and Tore Supra (Centre d'Etudes Nucleaire, Cadarache, France). Each antenna has been designed to deliver 4 MW of power. The electrical circuit and the mechanical philosophy employed are the same for both antennas, but different operating environments lead to substantial differences in the designs of specific components. A description and a comparison of the technologies developed in the two designs are presented. 5 refs., 4 figs., 1 tab

Status of material development for lifetime expansion of beryllium reflector

Energy Technology Data Exchange (ETDEWEB)

Dorn, C [Materion Brush Beryllium and Composites, California (United States); Tsuchiya, Kunihiko; Kawamura, Hiroshi [Japan Atomic Energy Agency, Oarai Research and Development Center, Oarai, Ibaraki (Japan); Hatano, Y [Univ. of Toyama, Toyama (Japan); Chakrov, P [INP-KNNC, Almaty (Kazakhstan); Kodama, M [Nippon Nuclear Fuel Development Co., Ltd., Oarai, Ibaraki (Japan)

2012-03-15

Beryllium has been used as the reflector element material in the reactor, specifically S-200F structural grade beryllium manufactured by Materion Brush Beryllium and Composites (former, Brush Wellman Inc.). As a part of the reactor upgrade, the Japan Atomic Energy Agency (JAEA) also has carried out the cooperation experiments to extend the operating lifetime of the beryllium reflector elements. It will first be necessary to determine which of the material's physical, mechanical and chemical properties will be the most influential on that choice. The irradiation testing plans to evaluate the various beryllium grades are also briefly considered and prepared. In this paper, material selection, irradiation test plan and PEI development for lifetime expansion of beryllium are described for material testing reactors. (author)

Precision segmented reflectors for space applications

Science.gov (United States)

Lehman, David H.; Pawlik, Eugene V.; Meinel, Aden B.; Fichter, W. B.

1990-08-01

A project to develop precision segmented reflectors (PSRs) which operate at submillimeter wavelengths is described. The development of a light efficient means for the construction of large-aperture segmented reflecting space-based telescopes is the primary aim of the project. The 20-m Large Deployable Reflector (LDR) telescope is being developed for a survey mission, and it will make use of the reflector panels and materials, structures, and figure control being elaborated for the PSR. The surface accuracy of a 0.9-m PSR panel is shown to be 1.74-micron RMS, the goal of 100-micron RMS positioning accuracy has been achieved for a 4-m erectable structure. A voice-coil actuator for the figure control system architecture demonstrated 1-micron panel control accuracy in a 3-axis evaluation. The PSR technology is demonstrated to be of value for several NASA projects involving optical communications and interferometers as well as missions which make use of large-diameter segmented reflectors.

Study of high speed complex number algorithms. [for determining antenna for field radiation patterns

Science.gov (United States)

Heisler, R.

1981-01-01

A method of evaluating the radiation integral on the curved surface of a reflecting antenna is presented. A three dimensional Fourier transform approach is used to generate a two dimensional radiation cross-section along a planer cut at any angle phi through the far field pattern. Salient to the method is an algorithm for evaluating a subset of the total three dimensional discrete Fourier transform results. The subset elements are selectively evaluated to yield data along a geometric plane of constant. The algorithm is extremely efficient so that computation of the induced surface currents via the physical optics approximation dominates the computer time required to compute a radiation pattern. Application to paraboloid reflectors with off-focus feeds in presented, but the method is easily extended to offset antenna systems and reflectors of arbitrary shapes. Numerical results were computed for both gain and phase and are compared with other published work.

Broadband standard dipole antenna for antenna calibration

Science.gov (United States)

Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

1995-06-01

Antenna calibration of EMI antennas is mostly performed by the standard antenna method at an open-field test site using a specially designed dipole antenna as a reference. In order to develop broadband standard antennas, the antenna factors of shortened dipples are theoretically investigated. First, the effects of the dipole length are analyzed using the induced emf method. Then, baluns and loads are examined to determine their influence on the antenna factors. It is found that transformer-type baluns are very effective for improving the height dependence of the antenna factors. Resistive loads are also useful for flattening the frequency dependence. Based on these studies, a specification is developed for a broadband standard antenna operating in the 30 to 150 MHz frequency range.

Development of film antenna for diversity reception; Diversity taio film antenna no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Shigeta, K; Taniguchi, T; Kubota, K [Mazda Motor Corp., Hiroshima (Japan)

1997-10-01

Based on the principle of capacitance-loaded window antennas, a new film antenna construction pasting an antenna element on a defogger element printed on a rear window was found. The film antennas show high reception performance, and can be used as television diversity antennas or a VICS-FM multiplex antenna. This paper describes the antenna design concept, the antenna construction and the application to a recreational vehicle which styling is 1.3-Box wagon for the electric accessory. 2 refs., 11 figs.

Rectangular Ring Antenna Excited by Circular Disc Monopole for WiMAX System

Directory of Open Access Journals (Sweden)

Souphanna Vongsack

2014-01-01

Full Text Available This research presents a rectangular ring antenna excited by a circular disc monopole (CDM mounted in front of a square reflector. The proposed antenna is designed to cover a frequency range of 2.300–5.825 GHz and thereby is suitable for WiMAX applications. Multiple parametric studies were carried out using the CST Microwave Studio simulation program. A prototype antenna was fabricated and experimented. The measurements were taken and compared with the simulation results, which indicates good agreement between both results. The prototype antenna produces an impedance bandwidth (|S11| < −10 dB that covers the WiMAX frequency range and a constant unidirectional radiation pattern (θ=0° and ∅=90°. The minimum and maximum gains are 3.7 and 8.7 dBi, respectively. The proposed antenna is of compact size and has good unidirectional radiation performance. Thus, it is very suitable for a multitude of WiMAX applications.

Reconfigurable Plasma Antenna Array by Using Fluorescent Tube for Wi-Fi Application

Directory of Open Access Journals (Sweden)

H. Ja’afar

2016-06-01

Full Text Available This paper presents a new design of reconfigurable plasma antenna array using commercial fluorescent tube. A round shape reconfigurable plasma antenna array is proposed to collimate beam radiated by an omnidirectional antenna (monopole antenna operates at 2.4GHz in particular direction. The antenna design is consisted of monopole antenna located at the center of circular aluminum ground. The monopole antenna is surrounded by a cylindrical shell of conducting plasma. The plasma shield consists of 12 commercial fluorescent tubes aligned in series containing a mixture of Argon gas and mercury vapor which upon electrification forms plasma columns. The plasma behaves as a conductor and acts as a reflector in radiation, in the condition where plasma frequency,ωp is higher than operating frequency. From this concepts, when all plasma elements are activated or switched to ON, the radiation signal from monopole antenna will trapped inside the plasma blanket and meanwhile when one or more plasma elements is deactivated (switched OFF, the radiation from monopole antenna will escape. This antenna has the capability to change its patterns with beam direction at 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300° and 330° at frequency 2.4 GHz. The proposed antenna has been successfully fabricated and measured with conclusive results.

DESIGN, CONSTRUCTION AND IMPLEMENTATION OF A 3 METER SATELLITE DISH ANTENNA (PARABOLOID REFLECTORS)

OpenAIRE

Danladi A; Jerome G

2008-01-01

The objective of this work is to design, construct and implement a 3m diameter paraboloid reflector with a frequency allocation of 3GHZ and above. The design was achieved with the help of wire mesh, aluminum span, mild steel, aluminum foil and glass fiber. The designed model was able to pick up signal from Arabian Satellite CNN, Adamawa Broadcasting television station and other channels with the help of low noise amplification block (LNB)

Advanced reflector materials for solar concentrators

Science.gov (United States)

Jorgensen, Gary; Williams, Tom; Wendelin, Tim

1994-10-01

This paper describes the research and development at the US National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.

Highly miniaturised semi-loop meandered dual-band MIMO antenna system

KAUST Repository

Jehangir, Syed S.

2017-12-05

A novel dual-band two-element directional multiple-input-multiple-output (MIMO) antenna system is presented with 68% miniaturisation, which is achieved using a semi-loop meandered driven element and a small ground plane. The centre frequency of operation is 2 GHz. The antenna system covers two bands: the telemetry L-band 1.27-1.43 GHz and the global system for mobile communications/long-term evolution band 1.8-2.133 GHz. The simulation and measurement results are in good agreement. The proposed antenna system mimics the quasi-Yagi antenna configuration with a measured front-to-back ratio of around 15 dB at 1.35 GHz and 17 dB at 2 GHz, which is achieved without using a large ground plane, extra metallic structures, multiple reflector elements, or any complex technique. A gain of more than 5 dBi is measured for the single element with a total radiation efficiency of around 85% in both bands. The measured isolation of the proposed MIMO antenna is more than 15 dB with < 0.0785 measured envelope correlation coefficient values in both bands.

Highly miniaturised semi-loop meandered dual-band MIMO antenna system

KAUST Repository

Jehangir, Syed S.; Sharawi, Mohammad S.; Shamim, Atif

2017-01-01

A novel dual-band two-element directional multiple-input-multiple-output (MIMO) antenna system is presented with 68% miniaturisation, which is achieved using a semi-loop meandered driven element and a small ground plane. The centre frequency of operation is 2 GHz. The antenna system covers two bands: the telemetry L-band 1.27-1.43 GHz and the global system for mobile communications/long-term evolution band 1.8-2.133 GHz. The simulation and measurement results are in good agreement. The proposed antenna system mimics the quasi-Yagi antenna configuration with a measured front-to-back ratio of around 15 dB at 1.35 GHz and 17 dB at 2 GHz, which is achieved without using a large ground plane, extra metallic structures, multiple reflector elements, or any complex technique. A gain of more than 5 dBi is measured for the single element with a total radiation efficiency of around 85% in both bands. The measured isolation of the proposed MIMO antenna is more than 15 dB with < 0.0785 measured envelope correlation coefficient values in both bands.

3D printed 20/30-GHz dual-band offset stepped-reflector antenna

DEFF Research Database (Denmark)

Menendez, Laura G.; Kim, Oleksiy S.; Persson, Frank

2015-01-01

with a peak directivity of 36.7 dB and 40.4 dB at 20 and 30 GHz, respectively; this corresponds to an aperture efficiency of 61 % and 64 %, respectively. These results demonstrate that 3D printing is a viable manufacturing technology for medium-sized high-frequency antennas....

Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

Science.gov (United States)

Jangid, K. G.; Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

2016-03-01

This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

Cylinder-type bottom reflector

International Nuclear Information System (INIS)

Elter, C.; Fritz, R.; Kissel, K.F.; Schoening, J.

1982-01-01

Proposal of a bottom reflector for gas-cooled nuclear reactor plants with a pebble bed of spherical fuel elements, where the horizontal forces acting from the core and the bottom reflector upon the side reflector are equally distributed. This is attained by the upper edge of the bottom reflector being placed levelly and by the angle of inclination of the recesses varying. (orig.) [de

Gain Enhancement of a Microstrip Patch Antenna Using a Reflecting Layer

Directory of Open Access Journals (Sweden)

Anwer Sabah Mekki

2015-01-01

Full Text Available A low profile, unidirectional, dual layer, and narrow bandwidth microstrip patch antenna is designed to resonate at 2.45 GHz. The proposed antenna is suitable for specific applications, such as security and military systems, which require a narrow bandwidth and a small antenna size. This work is mainly focused on increasing the gain as well as reducing the size of the unidirectional patch antenna. The proposed antenna is simulated and measured. According to the simulated and measured results, it is shown that the unidirectional antenna has a higher gain and a higher front to back ratio (F/B than the bidirectional one. This is achieved by using a second flame retardant layer (FR-4, coated with an annealed copper of 0.035 mm at both sides, with an air gap of 0.04λ0 as a reflector. A gain of 5.2 dB with directivity of 7.6 dBi, F/B of 9.5 dB, and −18 dB return losses (S11 are achieved through the use of a dual substrate layer of FR-4 with a relative permittivity of 4.3 and a thickness of 1.6 mm. The proposed dual layer microstrip patch antenna has an impedance bandwidth of 2% and the designed antenna shows very low complexity during fabrication.

Development and test of the ZELT-3D computer code for unfolding power distributions using side reflector instrumentation signals

International Nuclear Information System (INIS)

Knob, P.J.

1983-01-01

The impossibility of using internal instrumentation in high temperature reactor with spherical fuel, lead to the development of an instrumentation system that will be able to monitorate power perturbations only using detectors located in the reflectors. This instrumentation is divided in three parts: one for each reflector, higher, lower and lateral. The development of a system located in the lateral reflector is shown. The system was tested for Kahter from IRE-KFA of very low dimensions and for the PNP-300 power reactor of very large dimensions. Good results were obtained. (E.G.) [pt

Surface Optimization Techniques for Deployable Reflectors, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Under this and several other programs, CTD has developed TEMBOREG deployable solid-surface reflectors (TEMBOREG Reflectors) to provide future NASA and Air Force...

Real-Time Imaging with Frequency Scanning Array Antenna for Industrial Inspection Applications at W band

Science.gov (United States)

Larumbe, Belen; Laviada, Jaime; Ibáñez-Loinaz, Asier; Teniente, Jorge

2018-01-01

A real-time imaging system based on a frequency scanning antenna for conveyor belt setups is presented in this paper. The frequency scanning antenna together with an inexpensive parabolic reflector operates at the W band enabling the detection of details with dimensions in the order of 2 mm. In addition, a low level of sidelobes is achieved by optimizing unequal dividers to window the power distribution for sidelobe reduction. Furthermore, the quality of the images is enhanced by the radiation pattern properties. The performance of the system is validated by showing simulation as well as experimental results obtained in real time, proving the feasibility of these kinds of frequency scanning antennas for cost-effective imaging applications.

Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

Energy Technology Data Exchange (ETDEWEB)

Jorgensen, G.; Gee, R.; DiGrazia, M.

2010-10-01

Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

Energy Technology Data Exchange (ETDEWEB)

Meena, M. L., E-mail: madan.meena.ece@gamil.com; Parmar, Girish, E-mail: girish-parmar2002@yahoo.com; Kumar, Mithilesh, E-mail: mith-kr@yahoo.com [Department of Electronics Engineering, Rajasthan Technical University, Kota (India)

2016-03-09

A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

Energy Technology Data Exchange (ETDEWEB)

Jangid, K. G.; Kulhar, V. S. [Department of Physics, Manipal University Jaipur, Jaipur-303007 (India); Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Bhatnagar, D., E-mail: dbhatnagar-2000@rediffmail.com [Microwave Lab, Department of Physics, University of Rajasthan, Jaipur-302004 (India)

2016-03-09

This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

A W-Band Radiometer with the Offset Parabolic Antenna for Radiometric Measurements

Directory of Open Access Journals (Sweden)

Li Wu

2016-01-01

Full Text Available This paper deals with the development of a W-band noise-adding radiometer which combines the millimeter-wave (MMW radiometric measurements with a high-resolution imager. The offset parabolic antenna is presented to achieve an accurate measurement and a high resolution. To reduce the cross-polarization level of the antenna, a multimode feed horn with a multistep structure is proposed to match the focal region fields of the reflector. It has advantages over the corrugated horns in lower mass and easier manufacturing. In addition, due to an unavoidable settling time for the noise-adding radiometer output signal passing through the low-pass filter, a theoretical criterion for the optimum duty cycle determination to reject extraneous contributions from the transient is proposed in this paper. The appropriate duty cycle threshold is 0.33 for the developed W-band radiometer. Also, a geometric correction method is presented to correct the obtained passive image suffering from a distortion for a better image interpretation. Preliminary experimental results are given to illustrate and verify the presented techniques.

Development of impedance matching technologies for ICRF antenna arrays

International Nuclear Information System (INIS)

Pinsker, R.I.

1998-01-01

All high-power ion cyclotron range of frequency (ICRF) heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time dependent on timescales as rapid as 10 -1 s, while the radio frequency (RF) generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the RF source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In 'lossy passive schemes', reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array. (author)

Development of impedance matching technologies for ICRF antenna arrays

International Nuclear Information System (INIS)

Pinsker, R.I.

1998-03-01

All high power ICRF heating systems include devices for matching the input impedance of the antenna array to the generator output impedance. For most types of antennas used, the input impedance is strongly time-dependent on timescales as rapid as 10-4 s, while the rf generators used are capable of producing full power only into a stationary load impedance. Hence, the dynamic response of the matching method is of great practical importance. In this paper, world-wide developments in this field over the past decade are reviewed. These techniques may be divided into several classes. The edge plasma parameters that determine the antenna array's input impedance may be controlled to maintain a fixed load impedance. The frequency of the rf source can be feedback controlled to compensate for changes in the edge plasma conditions, or fast variable tuning elements in the transmission line between the generator output and the antenna input connections can provide the necessary time-varying impedance transformation. In lossy passive schemes, reflected power due to the time-varying impedance of the antenna array is diverted to a dummy load. Each of these techniques can be applied to a pre-existing antenna system. If a new antenna is to be designed, recent advances allow the antenna array to have the intrinsic property of presenting a constant load to the feeding transmission lines despite the varying load seen by each antenna in the array

CNGS Reflector installed

CERN Multimedia

2006-01-01

A major component that will help target the CNGS neutrino beam for its 732km journey through the earth's crust, from CERN to the Gran Sasso laboratory in Italy, has been installed in its final position. The transport of the huge magnetic horn reflector through the CNGS access gallery. A team from CNGS and TS/IC, and the contractors DBS, transported the magnetic horn reflector on 5th December, in a carefully conducted operation that took just under two hours. The reflector is 7m long, 1.6m in diameter and 1.6 tonnes in weight. With only a matter of centimetres to spare on either side, the reflector was transported through the CNGS access gallery, before being installed in the experiment's target chamber. The larger of two magnetic horns, the reflector will help refocus sprays of high energy pions and kaons emitted after a 0.5MW stream of protons from the Super Proton Synchrotron (SPS) strikes nucleons in a graphite target. The horns are toroidal magnetic lenses and work with high pulsed currents: 150 kA f...

Analysis of the Emitted Wavelet of High-Resolution Bowtie GPR Antennas

Directory of Open Access Journals (Sweden)

Manuel Pereira

2009-06-01

Full Text Available Most Ground Penetrating Radars (GPR cover a wide frequency range by emitting very short time wavelets. In this work, we study in detail the wavelet emitted by two bowtie GPR antennas with nominal frequencies of 800 MHz and 1 GHz. Knowledge of this emitted wavelet allows us to extract as much information as possible from recorded signals, using advanced processing techniques and computer simulations. Following previously published methodology used by Rial et al. [1], which ensures system stability and reliability in data acquisition, a thorough analysis of the wavelet in both time and frequency domain is performed. Most of tests were carried out with air as propagation medium, allowing a proper analysis of the geometrical attenuation factor. Furthermore, we attempt to determine, for each antenna, a time zero in the records to allow us to correctly assign a position to the reflectors detected by the radar. Obtained results indicate that the time zero is not a constant value for the evaluated antennas, but instead depends on the characteristics of the material in contact with the antenna.

Development and Performance Evaluation of Light Shelves Using Width-Adjustable Reflectors

Directory of Open Access Journals (Sweden)

Heangwoo Lee

2018-01-01

Full Text Available In recent years, there has been an increase in the consumption of energy for lighting purposes, which has led to an increase in the number of studies being conducted on this subject. Most studies have focused on light shelves, which are daylighting systems used for reducing the lighting energy required for the interiors of buildings. However, the existing light shelves cannot actively deal with external environmental factors, which often lead to an infringement of the right to light during the night when the performance of the light shelf deteriorates. Therefore, in this study, we propose a light shelf with a width-adjustable reflector and verify its validity using a testbed. The reflector of the proposed light shelf system is modularized so that the length can be adjusted in stages. The optimum width of the light shelf is calculated in terms of the energy reduction and uniformity ratio improvement, and the obtained optimum width is varied depending on the season. We find that the width-adjustable reflector can save 20% and 21.6% more lighting energy than light shelves with fixed reflector widths of 0.3 m and 0.6 m, respectively.

Advanced Communication Technology Satellite (ACTS) Multibeam Antenna On-Orbit Performance

Science.gov (United States)

1995-01-01

The NASA Lewis Research Center's Advanced Communication Technology Satellite (ACTS) was launched in September 1993. ACTS introduced several new technologies, including a multibeam antenna (MBA) operating at extremely short wavelengths never before used in communications. This antenna, which has both fixed and rapidly reconfigurable high-energy spot beams (150 miles in diameter), serves users equipped with small antenna terminals. Extensive structural and thermal analyses have been performed for simulating the ACTS MBA on-orbit performance. The results show that the reflector surfaces (mainly the front subreflector), antenna support assembly, and metallic surfaces on the spacecraft body will be distorted because of the thermal effects of varying solar heating, which degrade the ACTS MBA performance. Since ACTS was launched, a number of evaluations have been performed to assess MBA performance in the space environment. For example, the on-orbit performance measurements found systematic environmental disturbances to the MBA beam pointing. These disturbances were found to be imposed by the attitude control system, antenna and spacecraft mechanical alignments, and on-orbit thermal effects. As a result, the MBA may not always exactly cover the intended service area. In addition, the on-orbit measurements showed that antenna pointing accuracy is the performance parameter most sensitive to thermal distortions on the front subreflector surface and antenna support assemblies. Several compensation approaches were tested and evaluated to restore on-orbit pointing stability. A combination of autotrack (75 percent of the time) and Earth sensor control (25 percent of the time) was found to be the best way to compensate for antenna pointing error during orbit. This approach greatly minimizes the effects of thermal distortions on antenna beam pointing.

Phased Array Antenna Testbed Development at the NASA Glenn Research Center

Science.gov (United States)

Lambert, Kevin M.; Kubat, Gregory; Johnson, Sandra K.; Anzic, Godfrey

2003-01-01

Ideal phased array antennas offer advantages for communication systems, such as wide-angle scanning and multibeam operation, which can be utilized in certain NASA applications. However, physically realizable, electronically steered, phased array antennas introduce additional system performance parameters, which must be included in the evaluation of the system. The NASA Glenn Research Center (GRC) is currently conducting research to identify these parameters and to develop the tools necessary to measure them. One of these tools is a testbed where phased array antennas may be operated in an environment that simulates their use. This paper describes the development of the testbed and its use in characterizing a particular K-Band, phased array antenna.

Tailored reflectors for illumination.

Science.gov (United States)

Jenkins, D; Winston, R

1996-04-01

We report on tailored reflector design methods that allow the placement of general illumination patterns onto a target plane. The use of a new integral design method based on the edge-ray principle of nonimaging optics gives much more compact reflector shapes by eliminating the need for a gap between the source and the reflector profile. In addition, the reflectivity of the reflector is incorporated as a design parameter. We show the performance of design for constant irradiance on a distant plane, and we show how a leading-edge-ray method may be used to achieve general illumination patterns on nearby targets.

Antenna analysis using neural networks

Science.gov (United States)

Smith, William T.

1992-01-01

Conventional computing schemes have long been used to analyze problems in electromagnetics (EM). The vast majority of EM applications require computationally intensive algorithms involving numerical integration and solutions to large systems of equations. The feasibility of using neural network computing algorithms for antenna analysis is investigated. The ultimate goal is to use a trained neural network algorithm to reduce the computational demands of existing reflector surface error compensation techniques. Neural networks are computational algorithms based on neurobiological systems. Neural nets consist of massively parallel interconnected nonlinear computational elements. They are often employed in pattern recognition and image processing problems. Recently, neural network analysis has been applied in the electromagnetics area for the design of frequency selective surfaces and beam forming networks. The backpropagation training algorithm was employed to simulate classical antenna array synthesis techniques. The Woodward-Lawson (W-L) and Dolph-Chebyshev (D-C) array pattern synthesis techniques were used to train the neural network. The inputs to the network were samples of the desired synthesis pattern. The outputs are the array element excitations required to synthesize the desired pattern. Once trained, the network is used to simulate the W-L or D-C techniques. Various sector patterns and cosecant-type patterns (27 total) generated using W-L synthesis were used to train the network. Desired pattern samples were then fed to the neural network. The outputs of the network were the simulated W-L excitations. A 20 element linear array was used. There were 41 input pattern samples with 40 output excitations (20 real parts, 20 imaginary). A comparison between the simulated and actual W-L techniques is shown for a triangular-shaped pattern. Dolph-Chebyshev is a different class of synthesis technique in that D-C is used for side lobe control as opposed to pattern

Modeling and analysis of a large deployable antenna structure

Science.gov (United States)

Chu, Zhengrong; Deng, Zongquan; Qi, Xiaozhi; Li, Bing

2014-02-01

One kind of large deployable antenna (LDA) structure is proposed by combining a number of basic deployable units in this paper. In order to avoid vibration caused by fast deployment speed of the mechanism, a braking system is used to control the spring-actuated system. Comparisons between the LDA structure and a similar structure used by the large deployable reflector (LDR) indicate that the former has potential for use in antennas with up to 30 m aperture due to its lighter weight. The LDA structure is designed to form a spherical surface found by the least square fitting method so that it can be symmetrical. In this case, the positions of the terminal points in the structure are determined by two principles. A method to calculate the cable network stretched on the LDA structure is developed, which combines the original force density method and the parabolic surface constraint. Genetic algorithm is applied to ensure that each cable reaches a desired tension, which avoids the non-convergence issue effectively. We find that the pattern for the front and rear cable net must be the same when finding the shape of the rear cable net, otherwise anticlastic surface would generate.

A new antenna concept for satellite communications

Science.gov (United States)

Skahill, G.; Ciccolella, D.

1982-01-01

A novel antenna configuration of two reflecting surfaces and a phased array is examined for application to satellite communications and shown to be superior in every respect to earlier designs for service to the continental United States from synchronous orbit. The vignetting that afflicts other two reflector optical systems is eliminated by use of a reflecting field element. The remaining aberrations, predominantly coma, are isolated in the time delay distribution at the surface of the array and can be compensated by ordinary array techniques. The optics exhibits infinite bandwidth and the frequency range is limited only by the design of the array.

Developing novel 3D antennas using advanced additive manufacturing technology

Science.gov (United States)

Mirzaee, Milad

In today's world of wireless communication systems, antenna engineering is rapidly advancing as the wireless services continue to expand in support of emerging commercial applications. Antennas play a key role in the performance of advanced transceiver systems where they serve to convert electric power to electromagnetic waves and vice versa. Researchers have held significant interest in developing this crucial component for wireless communication systems by employing a variety of design techniques. In the past few years, demands for electrically small antennas continues to increase, particularly among portable and mobile wireless devices, medical electronics and aerospace systems. This trend toward smaller electronic devices makes the three dimensional (3D) antennas very appealing, since they can be designed in a way to use every available space inside the devise. Additive Manufacturing (AM) method could help to find great solutions for the antennas design for next generation of wireless communication systems. In this thesis, the design and fabrication of 3D printed antennas using AM technology is studied. To demonstrate this application of AM, different types of antennas structures have been designed and fabricated using various manufacturing processes. This thesis studies, for the first time, embedded conductive 3D printed antennas using PolyLactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) for substrate parts and high temperature carbon paste for conductive parts which can be a good candidate to overcome the limitations of direct printing on 3D surfaces that is the most popular method to fabricate conductive parts of the antennas. This thesis also studies, for the first time, the fabrication of antennas with 3D printed conductive parts which can contribute to the new generation of 3D printed antennas.

Gain Enhanced On-Chip Folded Dipole Antenna Utilizing Artificial Magnetic Conductor at 94 GHz

KAUST Repository

Nafe, Mahmoud; Syed, Ahad; Shamim, Atif

2017-01-01

On-chip antennas suffer from low gain values and distorted radiation patterns due to lossy and high permittivity Si substrate. An ideal solution would be to isolate the lossy Si substrate from the antenna through a Perfect Electric Conductor (PEC) ground plane, however the typical CMOS stack up which has multiple metal layers embedded in a thin oxide layer does not permit this. In this work, an Artificial Magnetic Conductor (AMC) reflecting surface has been utilized to isolate the Si substrate from the antenna. Contrary to the previous reports, the AMC structure is completely embedded in the thin oxide layer with the ground plane above the Si substrate. In this approach, the AMC surface acts for the first time as both a reflector and a silicon shield. As a result the antenna radiation pattern is not distorted and its gain is improved by 8 dB. The fabricated prototype demonstrates good impedance and radiation characteristics.

Gain Enhanced On-Chip Folded Dipole Antenna Utilizing Artificial Magnetic Conductor at 94 GHz

KAUST Repository

Nafe, Mahmoud

2017-09-05

On-chip antennas suffer from low gain values and distorted radiation patterns due to lossy and high permittivity Si substrate. An ideal solution would be to isolate the lossy Si substrate from the antenna through a Perfect Electric Conductor (PEC) ground plane, however the typical CMOS stack up which has multiple metal layers embedded in a thin oxide layer does not permit this. In this work, an Artificial Magnetic Conductor (AMC) reflecting surface has been utilized to isolate the Si substrate from the antenna. Contrary to the previous reports, the AMC structure is completely embedded in the thin oxide layer with the ground plane above the Si substrate. In this approach, the AMC surface acts for the first time as both a reflector and a silicon shield. As a result the antenna radiation pattern is not distorted and its gain is improved by 8 dB. The fabricated prototype demonstrates good impedance and radiation characteristics.

Flat Engineered Multichannel Reflectors

Directory of Open Access Journals (Sweden)

V. S. Asadchy

2017-09-01

Full Text Available Recent advances in engineered gradient metasurfaces have enabled unprecedented opportunities for light manipulation using optically thin sheets, such as anomalous refraction, reflection, or focusing of an incident beam. Here, we introduce a concept of multichannel functional metasurfaces, which are able to control incoming and outgoing waves in a number of propagation directions simultaneously. In particular, we reveal a possibility to engineer multichannel reflectors. Under the assumption of reciprocity and energy conservation, we find that there exist three basic functionalities of such reflectors: specular, anomalous, and retroreflections. Multichannel response of a general flat reflector can be described by a combination of these functionalities. To demonstrate the potential of the introduced concept, we design and experimentally test three different multichannel reflectors: three- and five-channel retroreflectors and a three-channel power splitter. Furthermore, by extending the concept to reflectors supporting higher-order Floquet harmonics, we forecast the emergence of other multichannel flat devices, such as isolating mirrors, complex splitters, and multi-functional gratings.

Flat Engineered Multichannel Reflectors

Science.gov (United States)

Asadchy, V. S.; Díaz-Rubio, A.; Tcvetkova, S. N.; Kwon, D.-H.; Elsakka, A.; Albooyeh, M.; Tretyakov, S. A.

2017-07-01

Recent advances in engineered gradient metasurfaces have enabled unprecedented opportunities for light manipulation using optically thin sheets, such as anomalous refraction, reflection, or focusing of an incident beam. Here, we introduce a concept of multichannel functional metasurfaces, which are able to control incoming and outgoing waves in a number of propagation directions simultaneously. In particular, we reveal a possibility to engineer multichannel reflectors. Under the assumption of reciprocity and energy conservation, we find that there exist three basic functionalities of such reflectors: specular, anomalous, and retroreflections. Multichannel response of a general flat reflector can be described by a combination of these functionalities. To demonstrate the potential of the introduced concept, we design and experimentally test three different multichannel reflectors: three- and five-channel retroreflectors and a three-channel power splitter. Furthermore, by extending the concept to reflectors supporting higher-order Floquet harmonics, we forecast the emergence of other multichannel flat devices, such as isolating mirrors, complex splitters, and multi-functional gratings.

Antenna concepts for interstellar search systems

International Nuclear Information System (INIS)

Basler, R.P.; Johnson, G.L.; Vondrak, R.R.

1977-01-01

An evaluation is made of microwave receiving systems designed to search for signals from extraterrestrial intelligence. Specific design concepts are analyzed parametrically to determine whether the optimum antenna system location is on earth, in space, or on the moon. Parameters considered include the hypothesized number of transmitting civilizations, the number of stars that must be searched to give any desired probability of receiving a signal, the antenna collecting area, the search time, the search range, and the cost. This analysis suggests that search systems based on the moon are not cost-competitive, if the search is extended only a few hundred light years from the earth, a Cyclops-type array on earth may be the most cost-effective system, for a search extending to 500 light years or more, a substantial cost and search-time advantage can be achieved with a large spherical reflector in space with multiple feeds, radio frequency interference shields can be provided for space systems, and cost can range from a few hundred million to tens of billions of dollars, depending on the parameter values assumed

Reflectors to Focus Wave Energy

DEFF Research Database (Denmark)

Kramer, Morten; Frigaard, Peter

2005-01-01

Wave Energy Converters (WEC’s) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased by approximately 30......-50%. Clearly longer wave reflectors will focus more wave energy than shorter wave reflectors. Thus the draw back is the increased wave forces for the longer wave reflectors. In the paper a procedure for calculating the energy efficiency and the wave forces on the reflectors are described, this by use of a 3D...... boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benefit for different wave reflector geometries and optimal geometrical design parameters are specified. On this basis inventors of WEC’s can...

Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas

Science.gov (United States)

Poduval, Dhruva

Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must be understood and optimized under multiple design constraints, e.g. substrate material properties and thicknesses, element to element spacing, and feed lines and their orientation and arrangements with respect to the antenna elements. The focus of this thesis is to investigate, design, and develop an aperture coupled patch array with wide operating bandwidth (30%), high gain (17.5 dBi), low side lobe level (20 dB), and high Forward to Backward (F/B) ratio (21.8 dB). The target frequency range is 2.4 to 3 GHz given its wide application in WLAN, LTE (Long Term Evolution) and other communication systems. Notwithstanding that the design concept can very well be adapted at other frequencies. Specifically, a 16 element, 4 by 4 planar microstrip patch array is designed using HFSS and experimentally developed and tested. Starting from mutual coupling minimization a corporate feeding scheme is designed to achieve the needed performance. To reduce the SLL the corporate feeding network is redesigned to obtain a specific amplitude taper. Studies are conducted to determine the optimum location for a metallic reflector under the feed line to improve the F/B. An experimental prototype of the antenna was built and tested validating and demonstrating the performance levels expected from simulation predictions

Development of ceramic-free antenna feeder

International Nuclear Information System (INIS)

Moriyama, S.; Kimura, H.; Fujii, T.; Saigusa, M.; Arai, H.

1994-01-01

We have proposed a ceramics-free antenna feeder line employing a ridged waveguide as a local support for IC antenna of next-generation tokamaks. One fourth mock-up model of the all metal waveguide designed for the ITER ICRF system is fabricated and electrical characteristics of the model including the coaxial line - waveguide converter are measured. Power reflection coefficient of the model including the coax-waveguide converter to the input coaxial line is estimated to be less than 15% below the cut-off frequency of 107 MHz and less than 3% above the cut-off frequency. It is found that this ceramics-free antenna support employing a ridged waveguide is quite available for IC antenna of next-generation tokamaks. (author)

Thermal Stability of a 4 Meter Primary Reflector for the Scanning Microwave Limb Sounder

Science.gov (United States)

Cofield, Richard E.; Kasl, Eldon P.

2011-01-01

The Scanning Microwave Limb Sounder (SMLS) is a space-borne heterodyne radiometer which will measure pressure, temperature and atmospheric constituents from thermal emission in [180,680] GHz. SMLS, planned for the NRC Decadal Survey's Global Atmospheric Composition Mission, uses a novel toric Cassegrain antenna to perform both elevation and azimuth scanning. This provides better horizontal and temporal resolution and coverage than were possible with elevation-only scanning in the two previous MLS satellite instruments. SMLS is diffraction-limited in the vertical plane but highly astigmatic in the horizontal (beam aspect ratio approx. 1:20). Nadir symmetry ensures that beam shape is nearly invariant over plus or minus 65 deg azimuth. A low-noise receiver FOV is swept over the reflector system by a small azimuth-scanning mirror. We describe the fabrication and thermal-stability test of a composite demonstration primary reflector, having full 4m height and 1/3 the width planned for flight. Using finite-element models of reflectors and structure, we evaluate thermal deformations and optical performance for 4 orbital environments and isothermal soak. We compare deformations with photogrammetric measurements made during soak tests in a chamber. The test temperature range exceeds predicted orbital ranges by large factors, implying in-orbit thermal stability of 0.21 micron rms (root mean square)/C, which meets SMLS requirements.

Space station high gain antenna concept definition and technology development

Science.gov (United States)

Wade, W. D.

1972-01-01

The layout of a technology base is reported from which a mechanically gimballed, directional antenna can be developed to support a manned space station proposed for the late 1970's. The effort includes the concept definition for the antenna assembly, an evaluation of available technology, the design of critical subassemblies and the design of critical subassembly tests.

Computational Electromagnetic Studies for Low-Frequency Compensation of the Reflector Impulse-radiating Antenna

Science.gov (United States)

2015-03-26

like the “winner”. Now the time domain characteris- tics are compared for a full understanding of the antenna performance. The boresight impulse...radio frequency distinct native attributes 121 TD time domain TDR time domain reflectometry TEM transverse electromagnetic TRP total radiated power UHF...cies. These undesirable backlobes have never been hypothesized, predicted or mea- sured, likely due in part to their alignment outside the primary

System concept for a moderate cost Large Deployable Reflector (LDR)

Science.gov (United States)

Swanson, P. N.; Breckinridge, J. B.; Diner, A.; Freeland, R. E.; Irace, W. R.; Mcelroy, P. M.; Meinel, A. B.; Tolivar, A. F.

1986-01-01

A study was carried out at JPL during the first quarter of 1985 to develop a system concept for NASA's LDR. Major features of the concept are a four-mirror, two-stage optical system; a lightweight structural composite segmented primary reflector; and a deployable truss backup structure with integral thermal shield. The two-stage optics uses active figure control at the quaternary reflector located at the primary reflector exit pupil, allowing the large primary to be passive. The lightweight composite reflector panels limit the short-wavelength operation to approximately 30 microns but reduce the total primary reflector weight by a factor of 3 to 4 over competing technologies. On-orbit thermal analysis indicates a primary reflector equilibrium temperature of less than 200 K with a maximum gradient of about 5 C across the 20-m aperture. Weight and volume estimates are consistent with a single Shuttle launch, and are based on Space Station assembly and checkout.

Localization of the pumping reflector for a Nd:YAG laser

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang Suk; Kim, Chul Joong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1994-12-01

For the first year plan of this program, the pumping reflectors, which are gold plated reflectors and ceramic diffuse reflectors, of the Nd:YAG laser have been localized. The laser output performances with these reflectors have been investigated. Developed reflectors can be applied successfully to our commercialized Nd:YAG laser which was worked in previous project. We designed the optical pumping system with GaAlAs diode laser bar to improve the pumping efficiency. Moreover, we investigated a simple pumping technique without changing the fleshlamp, which makes the Nd:YAG laser operate in a cw, a pulsed, and a mixed of the two mode. We expert many new applications of this diversification of output pulse shapes in industry and in medicine. 38 figs, 9 tabs, 18 refs. (Author).

Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors

Science.gov (United States)

Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea

2005-01-01

Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.

Development of Novel Integrated Antennas for CubeSats

Data.gov (United States)

National Aeronautics and Space Administration — The antenna system on a small satellite is a critical component, as a failure of the antenna can lead to mission failure. Present antenna systems are typically wire...

Application of adaptive antenna techniques to future commercial satellite communication

Science.gov (United States)

Ersoy, L.; Lee, E. A.; Matthews, E. W.

1987-01-01

The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further sub-divided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems.

Nonimaging reflectors for efficient uniform illumination.

Science.gov (United States)

Gordon, J M; Kashin, P; Rabl, A

1992-10-01

Nonimaging reflectors that are an extension of the design principle that was developed for compound parabolic concentrator type devices are proposed for illumination applications. The optical designs presented offer maximal lighting efficiency while they retain sharp angular control of the radiation and highly uniform flux densities on distant target planes. Our results are presented for symmetrical configurations in two dimensions (troughlike reflectors) for flat and for tubular sources. For fields of view of practical interest (half-angle in the 30-60 degrees range), these devices can achieve minimum-tomaximum intensity ratios of 0.7, while they remain compact and incur low reflective losses.

Preliminary Antenna Concept for the ngVLA

Science.gov (United States)

Di Francesco, James; Selina, Robert; Grammer, Wes; McKinnon, Mark M.

2017-01-01

The preliminary concept for a Next Generation Very Large Array (ngVLA) calls for an interferometric array having an effective collecting area and spatial resolution that are both 10 times better than that of the current VLA and operating over a frequency range of 1.2-116 GHz. Given the large number of antennas needed to meet the collecting area goal, the ngVLA antenna concept must strike a balance between competing science requirements and the programmatic targets for the array’s life cycle cost.Antenna diameters currently under consideration for the ngVLA are in the range of 12-25 m, with a nominal 18-m diameter aperture used for the conceptual design. Currently, the optimization for operations and construction cost suggests that a smaller number of larger apertures is preferable.The surface accuracy goal for the antennas is 185 µm rms (λ/16 @ 100 GHz) for the primary and subreflector combined under optimal environmental conditions. The subreflector will be optimized for performance above 10 GHz, with some degradation in aperture efficiency accepted at lower frequencies.For high dynamic range imaging, particularly at the low end of the ngVLA’s frequency range, the optimum optical configuration is likely an offset geometry. An unblocked aperture will minimize scattering, spillover, and sidelobe pickup. Both performance and maintenance requirements favor a receiver feedarm on the low side of the reflector.High pointing accuracy will also be necessary to provide the imaging dynamic range required of the system. With an unblocked aperture, variations in the antenna gain pattern are expected to be dominated by pointing errors. Preliminary requirements are for an absolute pointing accuracy of 40” RMS, with referenced pointing of 3” RMS (FWHM/10 at 10 GHz and 120 GHz, respectively, for an 18-m diameter dish).The antenna mount is expected to be a typical altitude-azimuth design. Both pedestal bearing and rail-based azimuth drives are under consideration. If fast

The healthiness of JT-60 ICRF antenna and development of its temperature measurement device

International Nuclear Information System (INIS)

Hiranai, Shinichi; Yokokura, Kenji; Moriyama, Shinichi; Sato, Tomio; Ishii, Kazuhiro; Fujii, Tsuneyuki

1998-03-01

Ion Cyclotron Range of Frequency (ICRF) heating system in JT-60 employs two antennas to couple RF power in the range of 100 MHz to the plasma. The antennas are installed in the vacuum vessel of JT-60, facing to the high temperature plasma. Due to the severe heat load from the plasma, parts of the antenna surface are suffering from melt. It is important to investigate the mechanism of the heat load and the melting. 'Temperature measurement for ICRF antenna surface' employing an infrared thermographic camera has been developed, in order to investigate the heat load to the antenna and to maintain the antenna available. We have succeeded in minimizing the melting damage of the antenna surface using the temperature measurement device. (author)

An estimation of the electrical characteristics of planetary shallow subsurfaces with TAPIR antennas

Science.gov (United States)

Le Gall, A.; Reineix, A.; Ciarletti, V.; Berthelier, J. J.; Ney, R.; Dolon, F.; Corbel, C.

2006-06-01

In the frame of the NETLANDER program, we have developed the Terrestrial And Planetary Investigation by Radar (TAPIR) imaging ground-penetrating radar to explore the Martian subsurface at kilometric depths and search for potential water reservoirs. This instrument which is to operate from a fixed lander is based on a new concept which allows one to image the various underground reflectors by determining the direction of propagation of the reflected waves. The electrical parameters of the shallow subsurface (permittivity and conductivity) need to be known to correctly determine the propagation vector. In addition, these electrical parameters can bring valuable information on the nature of the materials close to the surface. The electric antennas of the radar are 35 m long resistively loaded monopoles that are laid on the ground. Their impedance, measured during a dedicated mode of operation of the radar, depends on the electrical parameters of soil and is used to infer the permittivity and conductivity of the upper layer of the subsurface. This paper presents an experimental and theoretical study of the antenna impedance and shows that the frequency profile of the antenna complex impedance can be used to retrieve the geoelectrical characteristics of the soil. Comparisons between a numerical modeling and in situ measurements have been successfully carried over various soils, showing a very good agreement.

Final Technical Report: Development of an Abrasion-Resistant Antisoiling Coating for Front-Surface Reflectors

Energy Technology Data Exchange (ETDEWEB)

Gee, Randy C. [Sundog Solar Technology, Arvada, CO (United States)

2017-07-18

A high-performance reflective film has been successfully developed for Concentrating Solar Power (CSP) solar concentrators. Anti-soiling properties and abrasion resistance have been incorporated into the reflector to reduce reflector cleaning costs and to enhance durability. This approach has also resulted in higher reflectance and improved specularity. From the outset of this project we focused on the use of established high-volume roll-to-roll manufacturing techniques to achieve low manufacturing costs on a per ubit area basis. Roll-to-roll manufacturng equipment has a high capital cost so there is an entire industry devoted to roll-to-roll “toll” manufacturing, where the equipment is operated “around the clock” to produce a multitude of products for a large variety of uses. Using this approach, the reflective film can be manufactured by toll coaters/converters on an as-needed basis.

Detection Performance of Upgraded "Polished Panel" Optical Receiver Concept on the Deep-Space Network's 34 Meter Research Antenna

Science.gov (United States)

Vilnrotter, Victor A.

2012-01-01

The development and demonstration of a "polished panel" optical receiver concept on the 34 meter research antenna of the Deep Space Network (DSN) has been the subject of recent papers. This concept would enable simultaneous reception of optical and microwave signals by retaining the original shape of the main reflector for microwave reception, but with the aluminum panels polished to high reflectivity to enable focusing of optical signal energy as well. A test setup has been installed on the DSN's 34 meter research antenna at Deep Space Station 13 (DSS-13) of NASA's Goldstone Communications Complex in California, and preliminary experimental results have been obtained. This paper describes the results of our latest efforts to improve the point-spread function (PSF) generated by a custom polished panel, in an attempt to reduce the dimensions of the PSF, thus enabling more precise tracking and improved detection performance. The design of the new mechanical support structure and its operation are described, and the results quantified in terms of improvements in collected signal energy and optical communications performance, based on data obtained while tracking the planet Jupiter with the 34 meter research antenna at DSS-13.

APPLICATION OF QUATERNIONS FOR REFLECTOR PARAMETER

Directory of Open Access Journals (Sweden)

I. A. Konyakhin

2016-09-01

Full Text Available Subject of Research. The paper deals with application of quaternions for optimization of reflector parameters at autocollimation measurements in comparison with a matrix method. Computer-based results on the quaternionic models are presented that have given the possibility to determine conditions of measurement error reduction in view of apriori information on the rotation axis position. The practical synthesis technique for tetrahedron reflector parameters using found ratios is considered. Method. Originally, received conditions for reduction of autocollimation system measurement error are determined with the use of a matrix method for definition of an angular object position as a set of three equivalent consecutive turns about coordinate axes. At realization of these conditions the numerous recalculation of orientation parameters between various systems of coordinates is necessary that increases complexity and reduces resulting accuracy of autocollimation system at practical measurements. The method of quaternions gives the possibility to analyze the change of an absolute angular position in space, thus, there are conditions of accuracy increase regardless of the used systems of coordinates. Main Results. Researches on the mathematical model have shown, that the orthogonal arrangement of two basic constant directions for autocollimator tetrahedron reflector is optimal with respect to criterion of measurement error reduction at bisection arrangement of actual turn axis against them. Practical Relevance. On the basis of the found ratios between tetrahedron reflector angles and angles of its initial orientation parameters we have developed a practical method of reflector synthesis for autocollimation measurements in case of apriori information on an actual turn axis at monitoring measurements of the shaft or pipelines deformations.

ENERGY-EFFICIENT PASSIVE ANTENNA CODE PULSE MODULATION DUE TO THE REFLECTION OF MICROWAVE SIGNAL

Directory of Open Access Journals (Sweden)

T. A. Ismailov

2015-01-01

Full Text Available The article describes an antenna in a corner reflector with a p-i-n-diodes, integrated with the housing transceiver, which allows not only to provide bidirectional communication with the base station as a result of multipath radio three times, but with minimal energy consumption to provide digitally transmit information on the reflected wave flow of any complexity, which allow to eliminate energy in the transmit path and extend the life of the device. 

Mechanical Development of a Very Non-Standard Patch Array Antenna for Extreme Environments

Science.gov (United States)

Hughes, Richard; Chamberlain, Neil; Jakoboski, Julie; Petkov, Mihail

2012-01-01

This paper describes the mechanical development of patch antenna arrays for the Juno mission. The patch arrays are part of a six-frequency microwave radiometer instrument that will be used to measure thermal emissions from Jupiter. The very harsh environmental conditions in Jupiter orbit, as well as a demanding launch environment, resulted in a design that departs radically from conventional printed circuit patch antennas. The paper discusses the development and qualification of the Juno patch array antennas, with emphasis on the materials approach that was devised to mitigate the effects of electron charging in Jupiter orbit.

Optimization of Surrounding Reflector Material for Hyb-WT

International Nuclear Information System (INIS)

Tariq Siddique, M.; Hong, Song Hee; Kim, Myung Hyun

2013-01-01

The choice of reflector material is crucial for fusion and hybrid reactors as it was for the fission reactors. Multiple reflector materials were studied for pure fusion blanket design. The purpose of reflector in fusion blanket is to enhance the tritium breeding ratio (TBR). In fusion fission hybrid blanket the roll of reflector is slightly changed as it include the fission core and the performance of fission core also needs to be optimized and evaluated with the choice of reflector material, along with the enhancement of TBR. The performance parameters of Hyb-WT are significantly influenced by the choice of reflector material. TiC is best for TRU transmutation, TBR and reduced the neutron wall loading and graphite is best for FP transmutation. Strategy of multi reflector materials gives the best TRU and FP transmutation performance and also enhanced TBR with reduced neutron wall loading and it is a better choice for Hyb-WT reflector. The neutron flux is primarily dominated by the fission neutrons

Reflector and Protections in a Sodium-cooled Fast Reactor: Modelling and Optimization

Science.gov (United States)

Blanchet, David; Fontaine, Bruno

2017-09-01

The ASTRID project (Advanced Sodium Technological Reactor for Industrial Demonstration) is a Generation IV nuclear reactor concept under development in France [1]. In this frame, studies are underway to optimize radial reflectors and protections. Considering radial protections made in natural boron carbide, this study is conducted to assess the neutronic performances of the MgO as the reference choice for reflector material, in comparison with other possible materials including a more conventional stainless steel. The analysis is based upon a simplified 1-D and 2-D deterministic modelling of the reactor, providing simplified interfaces between core, reflector and protections. Such models allow examining detailed reaction rate distributions; they also provide physical insights into local spectral effects occurring at the Core-Reflector and at the Reflector-Protection interfaces.

Enhancing the stepped solar still performance using internal and external reflectors

International Nuclear Information System (INIS)

Omara, Z.M.; Kabeel, A.E.; Younes, M.M.

2014-01-01

Highlights: • Stepped solar still with internal and external reflectors have been investigated. • The productivity of the modified stepped solar still is higher than conventional by 103%. • The productivity of stepped still with external mirror is higher than that for conventional still by 88%. - Abstract: The performance of stepped solar still with internal and external reflectors have been investigated in the current study. The reflectors are used to enhance energy input to the stepped still. The influence of internal and external (top and bottom) reflectors on the performance of the stepped solar still is investigated. A comparison between modified stepped solar still and conventional solar still is carried out to evaluate the developed desalination system performance under the same climate conditions. The results indicated that, during experimentation the productivity of the modified stepped solar still with internal and external (top and bottom) reflectors is higher than that for conventional still approximately by 125%. In this case the estimated cost of 1 l of distillate for stepped still with reflectors and conventional solar stills is approximately 0.031$ and 0.049$, respectively

WWER radial reflector modeling by diffusion codes

International Nuclear Information System (INIS)

Petkov, P. T.; Mittag, S.

2005-01-01

The two commonly used approaches to describe the WWER radial reflectors in diffusion codes, by albedo on the core-reflector boundary and by a ring of diffusive assembly size nodes, are discussed. The advantages and disadvantages of the first approach are presented first, then the Koebke's equivalence theory is outlined and its implementation for the WWER radial reflectors is discussed. Results for the WWER-1000 reactor are presented. Then the boundary conditions on the outer reflector boundary are discussed. The possibility to divide the library into fuel assembly and reflector parts and to generate each library by a separate code package is discussed. Finally, the homogenization errors for rodded assemblies are presented and discussed (Author)

Design of optically stable image reflector system.

Science.gov (United States)

Tsai, Chung-Yu

2013-08-01

The design of a partially optically stable (POS) reflector system, in which the exit ray direction and image pose are unchanged as the reflector system rotates about a specific directional vector, was presented in an earlier study by the current group [Appl. Phys. B100, 883-890 (2010)]. The present study further proposes an optically stable image (OSI) reflector system, in which not only is the optical stability property of the POS system retained, but the image position and total ray path length are also fixed. An analytical method is proposed for the design of OSI reflector systems comprising multiple reflectors. The validity of the proposed approach is demonstrated by means of two illustrative examples.

16 CFR 1512.16 - Requirements for reflectors.

Science.gov (United States)

2010-01-01

... 1512.16 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT... vehicle headlamps. The use of reflector combinations off the center plane of the bicycle (defined in...) Front reflector. The reflector or mount shall not contact the ground plane when the bicycle is resting...

Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

Science.gov (United States)

Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

2012-01-01

Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

Pyramidal-Reflector Solar Heater

Science.gov (United States)

1982-01-01

Motor-driven reflector compensates for seasonal changes in Sun's altitude. System has flat-plate absorbers mounted on north side of attic interior. Skylight window on south-facing roof admits Sunlight into attic, lined with mirrors that reflect light to absorbers. Reflectors are inner surfaces of a pyramid lying on its side with window at its base and absorber plates in a cross-sectional plane near its apex.

Development of Antennas for Subsurface Radars within ACE

DEFF Research Database (Denmark)

Yarovoy, Alexander; Meincke, Peter; Dauvignac, Jean-Yves

2007-01-01

The paper gives an overview of the joint activities of the ACE-2 partners in the area of antennas for surface penetrating radar. Main areas of joint research and development are discussed and main results of joint activities are presented. Special attention is given to experimental verification...

Design and development of a unit element microstrip antenna for aircraft collision avoidance system

Science.gov (United States)

De, Debajit; Sahu, Prasanna Kumar

2017-10-01

Aircraft/traffic alert and collision avoidance system (ACAS/TCAS) is an airborne system which is designed to provide the service as a last defense equipment for avoiding mid-air collisions between the aircraft. In the existing system, four monopole stub-elements are used as ACAS directional antenna and one blade type element is used as ACAS omnidirectional antenna. The existing ACAS antenna has some drawbacks such as low gain, large beamwidth, frequency and beam tuning/scanning issues etc. Antenna issues like unwanted signals reception may create difficulties to identify the possible threats. In this paper, the focus is on the design and development of a unit element microstrip antenna which can be used for ACAS application and to overcome the possible limitations associated with the existing techniques. Two proposed antenna models are presented here, which are single feed and dual feed microstrip dual patch slotted antenna. These are designed and simulated in CST Microwave Studio tool. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. A good reflection coefficient, Voltage Standing Wave Ratio (VSWR), narrow beamwidth, perfect directional radiation pattern, high gain and directivity make this proposed antenna a good candidate for this application.

Advanced Manufacture of Reflectors

Energy Technology Data Exchange (ETDEWEB)

Angel, Roger [Univ. of Arizona, Tucson, AZ (United States)

2014-12-17

The main project objective has been to develop an advanced gravity sag method for molding large glass solar reflectors with either line or point focus, and with long or short focal length. The method involves taking standard sized squares of glass, 1.65 m x 1.65 m, and shaping them by gravity sag into precision steel molds. The method is designed for high volume manufacture when incorporated into a production line with separate pre-heating and cooling. The performance objectives for the self-supporting glass mirrors made by this project include mirror optical accuracy of 2 mrad root mean square (RMS), requiring surface slope errors less than 1 mrad rms, a target not met by current production of solar reflectors. Our objective also included development of new methods for rapidly shaping glass mirrors and coating them for higher reflectivity and soil resistance. Reflectivity of 95% for a glass mirror with anti-soil coating was targeted, compared to the present ~94% with no anti-soil coating. Our mirror cost objective is ~$20/m² in 2020, a significant reduction compared to the present ~$35/m² for solar trough mirrors produced for trough solar plants.

Research on optic antenna of space laser communication networking

Science.gov (United States)

Meng, Li-Xin; Li, Long; Zhang, Li-zhong; Zhao, Shan-shan; Jiang, Hui-lin

2013-08-01

With the highlights of the high transmission rate, large capacity, strong anti-interference and anti-capture ability, good security and small light, space laser communication becomes an important hotspot. At present, the focus of research of the laser communication system is point to point communication structure. However, from the application point of view, both the realization of space laser communication among multiple points and the establishment of the information transmission network can really have the practical value. Aiming at the problem of space laser communication network, this article puts forward the general idea about optical antenna to achieve multiple tracking goals at the same time. Through the analysis of the optical antenna, and the comparing of the current commonly used mirror driving mechanism, a new mirror driving mechanism is designed. The azimuth motion, containing circular grating feedback, is driven by torque motor，voice coil motor of fan produces pitch motion that has fan-shaped grating feedback, so that compression of the structure size to improve the efficiency of the reflector assembly. Through the establishment of the driving mechanism and the kinematic model of 3D entity, the relationship between the single drive azimuth and pitch angle following the angle of incident light is explained. The biggest ideal view area affecting the optical antenna is obtained by the simulation analysis of the kinematics model using MATLAB. The several factors of field overlap area and blind area offers a theoretical basis for structure optimization and control system for the subsequent optical antenna design.

The Planck Telescope reflectors

Science.gov (United States)

Stute, Thomas

2004-09-01

The mechanical division of EADS-Astrium GmbH, Friedrichshafen is currently engaged with the development, manufacturing and testing of the advanced dimensionally stable composite reflectors for the ESA satellite borne telescope Planck. The objective of the ESA mission Planck is to analyse the first light that filled the universe, the cosmic microwave background radiation. Under contract of the Danish Space Research Institute and ESA EADS-Astrium GmbH is developing the all CFRP primary and secondary reflectors for the 1.5-metre telescope which is the main instrument of the Planck satellite. The operational frequency ranges from to 25 GHz to 1000 GHz. The demanding high contour accuracy and surface roughness requirements are met. The design provides the extreme dimensional stability required by the cryogenic operational environment at around 40 K. The elliptical off-axis reflectors display a classical lightweight sandwich design with CFRP core and facesheets. Isostatic mounts provide the interfaces to the telescope structure. Protected VDA provides the reflecting surface. The manufacturing is performed at the Friedrichshafen premises of EADS-Space Transportation GmbH, the former Dornier composite workshops. Advanced manufacturing technologies like true angle lay-up by CNC fibre placement and filament winding are utilized. The protected coating is applied at the CAHA facilities at the Calar Alto Observatory, Spain. The exhaustive environmental testing is performed at the facilities of IABG, Munich (mechanical testing) and for the cryo-optical tests at CSL Liege. The project is in advanced state with both Qualification Models being under environmental testing. The flight models will be delivered in 2004. The paper gives an overview over the requirements and the main structural features how these requirements are met. Special production aspects and available test results are reported.

Lamp with a truncated reflector cup

Science.gov (United States)

Li, Ming; Allen, Steven C.; Bazydola, Sarah; Ghiu, Camil-Daniel

2013-10-15

A lamp assembly, and method for making same. The lamp assembly includes first and second truncated reflector cups. The lamp assembly also includes at least one base plate disposed between the first and second truncated reflector cups, and a light engine disposed on a top surface of the at least one base plate. The light engine is configured to emit light to be reflected by one of the first and second truncated reflector cups.

Development of local oscillator integrated antenna array for microwave imaging diagnostics

International Nuclear Information System (INIS)

Kuwahara, D.; Shinohara, S.; Ito, N.; Nagayama, Y.; Tsuchiya, H.; Yoshikawa, M.; Kohagura, J.; Yoshinaga, T.; Yamaguchi, S.; Kogi, Y.; Mase, A.

2015-01-01

Microwave imaging diagnostics are powerful tools that are used to obtain details of complex structures and behaviors of such systems as magnetically confined plasmas. For example, microwave imaging reflectometry and microwave imaging interferometers are suitable for observing phenomena that are involved with electron density fluctuations; moreover, electron cyclotron emission imaging diagnostics enable us to accomplish the significant task of observing MHD instabilities in large tokamaks. However, microwave imaging systems include difficulties in terms of multi-channelization and cost. Recently, we solved these problems by developing a Horn-antenna Mixer Array (HMA), a 50 - 110 GHz 1-D heterodyne- type antenna array, which can be easily stacked as a 2-D receiving array, because it uses an end-fire element. However, the HMA still evidenced problems owing to the requirement for local oscillation (LO) optics and an expensive high-power LO source. To solve this problem, we have developed an upgraded HMA, named the Local Integrated Antenna array (LIA), in which each channel has an internal LO supply using a frequency multiplier integrated circuit. Therefore, the proposed antenna array eliminates the need for both the LO optics and the high-power LO source. This paper describes the principle of the LIA, and provides details about an 8 channel prototype LIA

Apparatus including concave reflectors and a line of optical fibers

International Nuclear Information System (INIS)

Dolan, J.T.

1992-01-01

This patent describes an apparatus including a radiation source which emits in a multiplicity of directions for focusing radiation on an object which may receive radiation within a certain solid angle. It comprises a first reflector and a second reflector, the first reflector being elliptical in cross section and having a first focus and a second focus, the second reflector being circular in cross section and having a center, and a radius equal to the distance between the second reflector and the first focus, the first reflector and the second reflector being arranged so that a concave reflecting surface of the first reflector faces a concave reflecting surface of the second reflector, and so arranged that the first focus of the first reflector corresponds to the center of the second reflector, the radiation source being an elongated discharge bulb, the object being a group of two or more optical fibers defining at least one line of optical fibers which are located at the second focus of the first reflector

Highly accurate photogrammetric measurements of the Planck reflectors

Science.gov (United States)

Amiri Parian, Jafar; Gruen, Armin; Cozzani, Alessandro

2017-11-01

The Planck mission of the European Space Agency (ESA) is designed to image the anisotropies of the Cosmic Background Radiation Field over the whole sky. To achieve this aim, sophisticated reflectors are used as part of the Planck telescope receiving system. The system consists of secondary and primary reflectors which are sections of two different ellipsoids of revolution with mean diameters of 1 and 1.6 meters. Deformations of the reflectors which influence the optical parameters and the gain of receiving signals are investigated in vacuum and at very low temperatures. For this investigation, among the various high accuracy measurement techniques, photogrammetry was selected. With respect to the photogrammetric measurements, special considerations had to be taken into account in design steps, measurement arrangement and data processing to achieve very high accuracies. The determinability of additional parameters of the camera under the given network configuration, datum definition, reliability and precision issues as well as workspace limits and propagating errors from different sources are considered. We have designed an optimal photogrammetric network by heuristic simulation for the flight model of the primary and the secondary reflectors with relative precisions better than 1:1000'000 and 1:400'000 to achieve the requested accuracies. A least squares best fit ellipsoid method was developed to determine the optical parameters of the reflectors. In this paper we will report about the procedures, the network design and the results of real measurements.

Feasibility for the Use of Flat Booster Reflectors in Various Photovoltaic Installations

OpenAIRE

Gelegenis, John Joachim; Axaopoulos, Petros; Misailidis, Stavros; Giannakidis, George; Samarakou, Maria; Bonaros, Bassilios

2016-01-01

The feasibility for the addition of flat booster reflectors to PV panels is techno-economically investigated for various applications (building attached PVs, ground installations, grid-connected or stand-alone units) and various PV types (mono-crystalline and amorphous silicon PV panels). A model developed to this aim is applied to optimize the parameters of the PV/reflector module and to evaluate its applicability according to the solar radiation data of Athens (Greece). The reflectors may l...

Handbook of antenna technologies

CERN Document Server

Liu, Duixian; Nakano, Hisamatsu; Qing, Xianming; Zwick, Thomas

2016-01-01

The Handbook of Antenna Technologies aims to present the rapid development of antenna technologies, particularly in the past two decades, and also showcasing the newly developed technologies and the latest applications. The handbook will provide readers with the comprehensive updated reference information covering theory, modeling and optimization methods, design and measurement, new electromagnetic materials, and applications of antennas. The handbook will widely cover not only all key antenna design issues but also fundamentals, issues related to antennas (transmission, propagation, feeding structure, materials, fabrication, measurement, system, and unique design challenges in specific applications). This handbook will benefit the readers as a full and quick technical reference with a high-level historic review of technology, detailed technical descriptions and the latest practical applications.

Reflector modelization for neutronic diffusion and parameters identification

International Nuclear Information System (INIS)

Argaud, J.P.

1993-04-01

Physical parameters of neutronic diffusion equations can be adjusted to decrease calculations-measurements errors. The reflector being always difficult to modelize, we choose to elaborate a new reflector model and to use the parameters of this model as adjustment coefficients in the identification procedure. Using theoretical results, and also the physical behaviour of neutronic flux solutions, the reflector model consists then in its replacement by boundary conditions for the diffusion equations on the core only. This theoretical result of non-local operator relations leads then to some discrete approximations by taking into account the multiscaled behaviour, on the core-reflector interface, of neutronic diffusion solutions. The resulting model of this approach is then compared with previous reflector modelizations, and first results indicate that this new model gives the same representation of reflector for the core than previous. (author). 12 refs

Reflector-moderated critical assemblies

International Nuclear Information System (INIS)

Paxton, H.C.; Jarvis, G.A.; Byers, C.C.

1975-07-01

Experiments with reflector-moderated critical assemblies were part of the Rover Program at the Los Alamos Scientific Laboratory (LASL). These assemblies were characterized by thick D 2 O or beryllium reflectors surrounding large cavities that contained highly enriched uranium at low average densities. Because interest in this type of system has been revived by LASL Plasma Cavity Assembly studies, more detailed descriptions of the early assemblies than had been available in the unclassified literature are provided. (U.S.)

A Modular Approach To Developing A Large Deployable Reflector

Science.gov (United States)

Pittman, R.; Leidich, C.; Mascy, F.; Swenson, B.

1984-01-01

NASA is currently studying the feasibility of developing a Large Deployable Reflector (LDR) astronomical facility to perform astrophysical studies of the infrared and submillimeter portion of the spectrum in the mid 1990's. The LDR concept was recommended by the Astronomy Survey Committee of the National Academy of Sciences as one of two space based projects to be started this decade. The current baseline calls for a 20 m (65.6 ft) aperture telescope diffraction limited at 30 μm and automatically deployed from a single Shuttle launch. The volume, performance, and single launch constraints place great demands on the technology and place LDR beyond the state-of-the-art in certain areas such as lightweight reflector segments. The advent of the Shuttle is opening up many new options and capabilities for producing large space systems. Until now, LDR has always been conceived as an integrated system, deployed autonomously in a single launch. This paper will look at a combination of automatic deployment and on-orbit assembly that may reduce the technological complexity and cost of the LDR system. Many technological tools are now in use or under study that will greatly enhance our capabilities to do assembly in space. Two Shuttle volume budget scenarios will be examined to assess the potential of these tools to reduce the LDR system complexity. Further study will be required to reach the full optimal combination of deployment and assembly, since in most cases the capabilities of these new tools have not been demonstrated. In order to take maximum advantage of these concepts, the design of LDR must be flexible and allow one subsystem to be modified without adversely affecting the entire system. One method of achieving this flexibility is to use a modular design approach in which the major subsystems are physically separated during launch and assembled on orbit. A modular design approach facilitates this flexibility but requires that the subsystems be interfaced in a simple

Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

Science.gov (United States)

Britcliffe, M. J.; Hoppe, D. J.

2001-01-01

The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

Development of the Aquarius Antenna Deployment Mechanisms and Spring/Damper Actuator

Science.gov (United States)

Johnson, Joel A.

2008-01-01

The Aquarius Instrument s large radar reflector dish needed to be stowed for launch, and then deployed on-orbit. The Deployment Subsystem consisted of a cantilevered boom structure and two single-axis hinge mechanisms to accurately deploy and position the reflector dish relative to the radar feed horns. The cantilevered design demanded high stiffness and accuracy from the deployment mechanism at the root of the boom. A preload-generating end-of-travel latch was also required. To largely eliminate the need for control systems, each deployment mechanism was actuated by a passive spring motor with viscous-fluid damping. Tough requirements and adaptation of a heritage actuator to the new application resulted in numerous challenges. Fabrication, assembly, and testing encountered additional problems, though ultimately the system was demonstrated very successfully. This paper revisits the development to highlight which design concepts worked and the many important lessons learned.

Reflector construction by sound path curves - A method of manual reflector evaluation in the field

International Nuclear Information System (INIS)

Siciliano, F.; Heumuller, R.

1985-01-01

In order to describe the time-of-flight behavior of various reflectors we have set up models and derived from them analytical and graphic approaches to reflector reconstruction. In the course of this work, maximum achievable accuracy and possible simplifications were investigated. The aim of the time-of-flight reconstruction method is to determine the points of a reflector on the basis of a sound path function (sound path as the function of the probe index position). This method can only be used on materials which are isotropic in terms of sound velocity since the method relies on time of flight being converted into sound path. This paper deals only with two-dimensional reconstruction, in other words all statements relate to the plane of incidence. The method is based on the fact that the geometrical location of the points equidistant from a certain probe index position is a circle. If circles with radiuses equal to the associated sound path are drawn for various search unit positions the points of intersection of the circles are the desired reflector points

A figure control sensor for the Large Deployable Reflector (LDR)

Science.gov (United States)

Bartman, R.; Dubovitsky, S.

1988-01-01

A sensing and control system is required to maintain high optical figure quality in a segmented reflector. Upon detecting a deviation of the segmented surface from its ideal form, the system drives segment mounted actuators to realign the individual segments and thereby return the surface to its intended figure. When the reflector is in use, a set of figure sensors will determine positions of a number of points on the back surface of each of the reflector's segments, each sensor being assigned to a single point. By measuring the positional deviations of these points from previously established nominal values, the figure sensors provide the control system with the information required to maintain the reflector's optical figure. The optical lever, multiple wavelength interferometer, and electronic capacitive sensor, the most promising technologies for the development of the figure sensor, are illustrated. It is concluded that to select a particular implementation of the figure sensors, performance requirement will be refined and relevant technologies investigated further.

Research of flaw assessment methods for beryllium reflector elements

International Nuclear Information System (INIS)

Shibata, Akira; Ito, Masayasu; Takemoto, Noriyuki; Tanimoto, Masataka; Tsuchiya, Kunihiko; Nakatsuka, Masafumi; Ohara, Hiroshi; Kodama, Mitsuhiro

2012-02-01

Reflector elements made from metal beryllium is widely used as neutron reflectors to increase neutron flux in test reactors. When beryllium reflector elements are irradiated by neutron, bending of reflector elements caused by swelling occurs, and beryllium reflector elements must be replaced in several years. In this report, literature search and investigation for non-destructive inspection of Beryllium and experiments for Preliminary inspection to establish post irradiation examination method for research of characteristics of metal beryllium under neutron irradiation were reported. (author)

A Reconfigurable Metal-Plasma Yagi-Yuda Antenna for Microwave Applications

Directory of Open Access Journals (Sweden)

Giulia Mansutti

2017-05-01

Full Text Available This paper is an extension of the work originally presented at the European Microwave Conference (EuMC about a reconfigurable hybrid metal-plasma Yagi-Uda antenna operating at 1.55 GHz: this antenna consists of metallic reflector and active element and two plasma directors. The conference work showed through full-wave numerical simulations (CST Microwave Studio how it is possible to achieve reconfigurability with respect to the gain by turning on/off the plasma discharges. However the model that was used to represent the plasma discharges was quite ideal, so one comment that was provided questioned the actual possibility of achieving reconfigurability in a real system. Consequently we performed extensive measurements of different plasma discharges and thanks to the collected data, we noticed some important differences between the full-wave numerical model of the plasma that we used in the conference paper and the actual plasma discharges that were generated in the experimental setup: the dielectric vessel and the metallic electrodes used respectively to confine and generate the plasma have an influence on the radiation pattern of the antenna and so they must be included in the design procedure; the cylindrical plasma discharge is much easier to realize when the cylinder diameter is at least 3mm; and finally the collision frequency of the plasma in realistic cases is pretty higher than the one adopted in our previous work. Therefore this work presents a feasibility study of a more detailed and realistic model of our antenna with respect to the plasma discharges. We will show that reconfigurability can still be achieved through a proper design of the overall antenna, thus paving the way to an actual realization of the proposed reconfigurable Yagi-Uda.

Vertical reflector for bifacial PV-panels

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

2016-01-01

Bifacial solar modules offer an interesting price/performance ratio, and much work has been focused on directing the ground albedo to the back of the solar cells. In this work we design and develop a reflector for a vertical bifacial panel, with the objective to optimize the energy harvest...

Radio antennas

Science.gov (United States)

Gibson, S. W.

This book is concerned with providing an explanation of the function of an antenna without delving too deeply into the mathematics or theory. The characteristics of an antenna are examined, taking into account aspects of antenna radiation, wave motion on the antenna, resistance in the antenna, impedance, the resonant antenna, the effect of the ground, polarization, radiation patterns, coupling effects between antenna elements, and receiving vs. transmitting. Aspects of propagation are considered along with the types of antennas, transmission lines, matching devices, questions of antenna design, antennas for the lower frequency bands, antennas for more than one band, limited space antennas, VHF antennas, and antennas for 20, 15, and 10 meters. Attention is given to devices for measuring antenna parameters, approaches for evaluating the antenna, questions of safety, and legal aspects.

The effects of stainless steel radial reflector on core reactivity for small modular reactor

Energy Technology Data Exchange (ETDEWEB)

Kang, Jung Kil, E-mail: jkkang@email.kings.ac.kr; Hah, Chang Joo, E-mail: changhah@kings.ac.kr [KINGS, 658-91, Haemaji-ro, Seosaeng-myeon, Ulju-gun, Ulsan, 689-882 (Korea, Republic of); Cho, Sung Ju, E-mail: sungju@knfc.co.kr; Seong, Ki Bong, E-mail: kbseong@knfc.co.kr [KNFC, Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2016-01-22

Commercial PWR core is surrounded by a radial reflector, which consists of a baffle and water. Radial reflector is designed to reflect neutron back into the core region to improve the neutron efficiency of the reactor and to protect the reactor vessels from the embrittling effects caused by irradiation during power operation. Reflector also helps to flatten the neutron flux and power distributions in the reactor core. The conceptual nuclear design for boron-free small modular reactor (SMR) under development in Korea requires to have the cycle length of 4∼5 years, rated power of 180 MWth and enrichment less than 5 w/o. The aim of this paper is to analyze the effects of stainless steel radial reflector on the performance of the SMR using UO{sub 2} fuels. Three types of reflectors such as water, water/stainless steel 304 mixture and stainless steel 304 are selected to investigate the effect on core reactivity. Additionally, the thickness of stainless steel and double layer reflector type are also investigated. CASMO-4/SIMULATE-3 code system is used for this analysis. The results of analysis show that single layer stainless steel reflector is the most efficient reflector.

Optimized reflectors for non-tracking solar collectors with tubular absorbers

Energy Technology Data Exchange (ETDEWEB)

Muschaweck, Julius [Optics and Energy Consulting, Munich (Germany); Spirkl, Wolfgang [Ludwig-Maximilians Univ., Sektion Physik, Munich (Germany); Timinger, Andreas [Optics and Energy Consulting, Munich (Germany); ZAE Bayern, Solar Thermal and Biomass Dept., Munich (Germany); Benz, Nikolaus; Doerfler, Michael; Gut, Martin [ZAE Bayern, Solar Thermal and Biomass Dept., Munich (Germany); Kose, Erwin [microtherm Energietecjnik GmbH, Lods, 25 (France)

2000-07-01

We present an approach to find optimal reflector shapes for non-tracking solar collectors under practical constraints. We focus on cylindrical absorbers and reflectors with translational symmetry. Under idealised circumstances, edge ray reflectors are well known to be optimal. However, it is not clear how optimal reflectors should be shaped in order to obtain maximum utilisable energy for given operating temperatures under practical constraints like reflectivity less than unity, real radiation data, size limits, and gaps between the reflector and the absorber. For a prototype collector with a symmetric edge ray reflector and a tubular absorber, we derive from calorimetric measurements under outdoor conditions the optical efficiency as a function of the incidence angle. Using numerical optimisation and raytracing, we compare truncated symmetric edge ray reflectors, truncated asymmetric edge ray reflectors and free forms parametrized by Bezier splines. We find that asymmetric edge ray reflectors are optimal. For reasonable operating conditions, truncated asymmetric edge ray reflectors allow much better land use and easily adapt to a large range of roof tilt angles with marginal changes in collector construction. Except near the equator, they should increase the yearly utilisable energy per absorber tube by several percent as compared to the prototype collector with symmetric reflectors. (Author)

Modeling of compact loop antennas

International Nuclear Information System (INIS)

Baity, F.W.

1987-01-01

A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

Ultra wideband antennas design, methodologies, and performance

CERN Document Server

Galvan-Tejada, Giselle M; Jardón Aguilar, Hildeberto

2015-01-01

Ultra Wideband Antennas: Design, Methodologies, and Performance presents the current state of the art of ultra wideband (UWB) antennas, from theory specific for these radiators to guidelines for the design of omnidirectional and directional UWB antennas. Offering a comprehensive overview of the latest UWB antenna research and development, this book:Discusses the developed theory for UWB antennas in frequency and time domainsDelivers a brief exposition of numerical methods for electromagnetics oriented to antennasDescribes solid-planar equivalen

Solar reflector

Energy Technology Data Exchange (ETDEWEB)

Dvorak, J

1983-01-15

The reflector in the form of part of a cylindrical surface delimited by two envelopes is installed on a platform which can move on an inclined curvilinear path. The angle of inclination of the path depends on the latitude of the locality. The reflected rays are focused on the tubular absorber. One of the axes of the platform is linked to a brake controlled by a sensor for intensity of solar radiation. The sensor is a pipe filled with liquid with high value of the temperature expansion coefficient, for example alcohol. The pipe is insulated from one side and is accessible to the solar rays from the opposite. One end of the pipe is equipped with a bending end or piston. In order to expand the fluid in the sensor, the pipe acts on the brake, and the reflector is installed in a position corresponding to the maximum radiation intensity.

Ellisoidal reflector for measuring otoacoustic emissions

DEFF Research Database (Denmark)

Epp, Bastian; Heiskanen, Vesa; Pulkki, Ville Topias

2016-01-01

ear canal. This study presents the design and evaluation of a truncated prolate ellipsoidal reflector in combination with a large-diaphragm low-noise microphone to measure OAEs in the open ear canal of human listeners. The reflector was designed to gain information about BM processing at low...

Optimization of reflector-boosters for solar flat-collectors

Energy Technology Data Exchange (ETDEWEB)

Profant, M; Weidner, P; Boettcher, A

1979-04-01

To increase the working temperature of solar energy systems two-sided collectors together with appropriate reflectors are used. Here, the efficiency of various reflector shapes was investigated and attempts made to optimize them under several criteria. The results indicate that with cheap and simple to manufacture reflectors good energy gains can be expected.

Design of partially optically stable reflector systems and prisms

Science.gov (United States)

Tsai, Chuang-Yu

2010-09-01

The characteristics and design method of the total optically stable (TOS) reflector systems/prisms were introduced in an early paper (Tsai and Lin in Appl. Opt. 47:4158-4163, 2008), where only two types of TOS reflector system exist, namely preservation or retroreflection. In this paper, we introduce the partially optically stable (POS) reflector system, which is only optically stable about a specific directional vector; nevertheless, the exiting light ray is not restricted to preservation or retroreflection. The proposed paper also presents an analytic method for the design of POS reflector systems comprised of multiple reflectors. Furthermore, it is shown that a POS prism can be obtained by adding two refracting flat boundary surfaces with specific conditions at the entrance and exit positions of the light ray in an optical system with multiple reflectors.

Antennas from theory to practice

CERN Document Server

Huang, Yi

2008-01-01

Practical, concise and complete reference for the basics of modern antenna design Antennas: from Theory to Practice discusses the basics of modern antenna design and theory. Developed specifically for engineers and designers who work with radio communications, radar and RF engineering, this book offers practical and hands-on treatment of antenna theory and techniques, and provides its readers the skills to analyse, design and measure various antennas. Key features: Provides thorough coverage on the basics of transmission lines, radio waves and propag

Integrated reconfigurable multiple-input–multiple-output antenna system with an ultra-wideband sensing antenna for cognitive radio platforms

KAUST Repository

Hussain, Rifaqat

2015-06-18

© The Institution of Engineering and Technology 2015. A compact, novel multi-mode, multi-band frequency reconfigurable multiple-input-multiple-output (MIMO) antenna system, integrated with ultra-wideband (UWB) sensing antenna, is presented. The developed model can be used as a complete antenna platform for cognitive radio applications. The antenna system is developed on a single substrate area of dimensions 65 × 120 mm². The proposed sensing antenna is used to cover a wide range of frequency bands from 710 to 3600 MHz. The frequency reconfigurable dual-element MIMO antenna is integrated with P-type, intrinsic, N-type (PIN) diodes for frequency agility. Different modes of selection are used for the MIMO antenna system reconfigurability to support different wireless system standards. The proposed MIMO antenna configuration is used to cover various frequency bands from 755 to 3450 MHz. The complete system comprising the multi-band reconfigurable MIMO antennas and UWB sensing antenna for cognitive radio applications is proposed with a compact form factor.

Effect of phototherapy with alumunium foil reflectors on neonatal hyperbilirubinemia

Directory of Open Access Journals (Sweden)

Tony Ijong Dachlan

2015-03-01

Full Text Available Background Neonatal hyperbilirubinemia (NH is one of the most common problems in neonates, but it can be treated with blue light phototherapy. Developing countries with limited medical equipment and funds have difficulty providing effective phototherapy to treat NH, leading to increased risk of bilirubin encephalopathy. Phototherapy with white reflecting curtains can decrease the duration of phototherapy needed to reduce bilirubin levels. Objective To compare the duration of phototherapy needed in neonates with NH who underwent phototherapy with and without aluminum foil reflectors. Methods This open clinical trial was conducted from July to August 2013 at Dr. Hasan Sadikin Hospital, Bandung, Indonesia. The inclusion criteria were term neonates with uncomplicated NH presenting in their first week of life. Subjects were randomized into two groups, those who received phototherapy with or without aluminum foil reflectors. Serum bilirubin is taken at 12th, 24th, 48th hours, then every 24 hours if needed until phototherapy can be stopped according to American Academy of Pediatrics guidelines. The outcome measured was the duration of phototherapy using survival analysis. The difference between the two groups was tested by Gehan method. Results Seventy newborns who fulfilled the inclusion criteria and had similar characteristics were randomized into two groups. The duration of phototherapy needed was significantly less in the group with aluminum foil reflectors than in the group without reflectors [72 vs. 96 hours, respectively, (P<0.01]. Conclusion The required duration of phototherapy with aluminum foil reflectors is significantly less than that of phototherapy without reflectors, in neonates with NH.

Design of node record for fast active reflector

International Nuclear Information System (INIS)

Wu Wenqing; Luo Mingcheng; Tang Pengyi; Liu Jiajing; Wang Jian

2014-01-01

Active Reflector is the one of the innovations of Five hundred meter Aperture Spherical Telescope (FAST) whose performance touches on that of the overall telescope. Therefore a real time control system is needed by the Active Reflector System. In this paper, a new record type-node record is designed for EPICS-based active reflector control system of FAST, according to more than 2000 controlled node, which will be convenient for node management of IOC and prove the reusage of IOC codes. The record type is used in design of active reflector control system of FAST Miyun model. (authors)

Reflector Performance Study in Ultra-long Cycle Fast Reactor

International Nuclear Information System (INIS)

Tak, Taewoo; Kong, Chidong; Choe, Jiwon; Lee, Deokjung

2013-01-01

There are reflector assemblies outside the fuel region, surrounding the fuel assemblies and axial reflector is located at the bottom of the core to control the neutron leakage fraction which is an important factor in fast reactor system. HT-9 was used as a reflector material as well as a structure material. In this study, alternative reflector materials were proposed and their reflection performance was tested and studied focused on its physics. ODS-MA957 and SiC were chosen from iron based alloy and ceramic respectively. The two materials were tested and compared with HT-9 in UCFR-1000 as a radial and an axial reflector and it was evaluated from the neutronics point of view with comparing the core life and the coolant void reactivity. The calculation and evaluation were performed by McCARD Monte Carlo code. The reflector materials for UCFR-1000 have been investigated in the aspect of neutronics. The reflection effect shows different performance corresponding to reflector material used. Also, the neutron energy spectrum is affected by changing materials which causes spectrum softening but it is not enough to influence the core life. With more reflector material candidates such as lead-based liquid metal, reflection performance and core parameter study will be investigated for next step

Approaching conversion limit with all-dielectric solar cell reflectors.

Science.gov (United States)

Fu, Sze Ming; Lai, Yi-Chun; Tseng, Chi Wei; Yan, Sheng Lun; Zhong, Yan Kai; Shen, Chang-Hong; Shieh, Jia-Min; Li, Yu-Ren; Cheng, Huang-Chung; Chi, Gou-chung; Yu, Peichen; Lin, Albert

2015-02-09

Metallic back reflectors has been used for thin-film and wafer-based solar cells for very long time. Nonetheless, the metallic mirrors might not be the best choices for photovoltaics. In this work, we show that solar cells with all-dielectric reflectors can surpass the best-configured metal-backed devices. Theoretical and experimental results all show that superior large-angle light scattering capability can be achieved by the diffuse medium reflectors, and the solar cell J-V enhancement is higher for solar cells using all-dielectric reflectors. Specifically, the measured diffused scattering efficiency (D.S.E.) of a diffuse medium reflector is >0.8 for the light trapping spectral range (600nm-1000nm), and the measured reflectance of a diffuse medium can be as high as silver if the geometry of embedded titanium oxide(TiO(2)) nanoparticles is optimized. Moreover, the diffuse medium reflectors have the additional advantage of room-temperature processing, low cost, and very high throughput. We believe that using all-dielectric solar cell reflectors is a way to approach the thermodynamic conversion limit by completely excluding metallic dissipation.

Transport equivalent diffusion constants for reflector region in PWRs

International Nuclear Information System (INIS)

Tahara, Yoshihisa; Sekimoto, Hiroshi

2002-01-01

The diffusion-theory-based nodal method is widely used in PWR core designs for reason of its high computing speed in three-dimensional calculations. The baffle/reflector (B/R) constants used in nodal calculations are usually calculated based on a one-dimensional transport calculation. However, to achieve high accuracy of assembly power prediction, two-dimensional model is needed. For this reason, the method for calculating transport equivalent diffusion constants of reflector material was developed so that the neutron currents on the material boundaries could be calculated exactly in diffusion calculations. Two-dimensional B/R constants were calculated using the transport equivalent diffusion constants in the two-dimensional diffusion calculation whose geometry reflected the actual material configuration in the reflector region. The two-dimensional B/R constants enabled us to predict assembly power within an error of 1.5% at hot full power conditions. (author)

Efficient Wave Energy Amplification with Wave Reflectors

DEFF Research Database (Denmark)

Kramer, Morten Mejlhede; Frigaard, Peter Bak

2002-01-01

Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

Present capabilities and new developments in antenna modeling with the numerical electromagnetics code NEC

Energy Technology Data Exchange (ETDEWEB)

Burke, G.J.

1988-04-08

Computer modeling of antennas, since its start in the late 1960's, has become a powerful and widely used tool for antenna design. Computer codes have been developed based on the Method-of-Moments, Geometrical Theory of Diffraction, or integration of Maxwell's equations. Of such tools, the Numerical Electromagnetics Code-Method of Moments (NEC) has become one of the most widely used codes for modeling resonant sized antennas. There are several reasons for this including the systematic updating and extension of its capabilities, extensive user-oriented documentation and accessibility of its developers for user assistance. The result is that there are estimated to be several hundred users of various versions of NEC world wide. 23 refs., 10 figs.

Effect of graphite reflector on activation of fusion breeding blanket

International Nuclear Information System (INIS)

Lee, Cheol Woo; Lee, Young-Ouk; Lee, Dong Won; Cho, Seungyon; Ahn, Mu-Young

2016-01-01

Highlights: • The graphite reflector concept has been applied in the design of the Korea HCCR TBM for ITER and this concept is also a candidate design option for Korea Demo. • In the graphite reflector, C-14, B-11 and Be-10 are produced after an irradiation. Impurities in both case of beryllium and graphite is dominant in the shutdown dose after an irradiation. • Based on the evaluation, the graphite reflector is a good alternative of the beryllium multiplier in the view of induced activity and shutdown dose. But C-14 produced in the graphite reflector should be considered carefully in the view of radwaste management. - Abstract: Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. In this paper, activity analysis was performed and the effect of graphite reflector in the view of activation was compared to the beryllium multiplier. As a result, it is expected that using the graphite reflector instead of the beryllium multiplier decreases total activity very effectively. But the graphite reflector produces C-14 about 17.2 times than the beryllium multiplier. Therefore, C-14 produced in the graphite reflector is expected as a significant nuclide in the view of radwaste management.

The reflector effect on the neutron lifetimes in the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Gonnelli, Eduardo

2013-01-01

The aim of this study is to present the reflector effect on the neutron lifetimes in the IPEN/MB-01 reactor. The proposed method requires an approach which takes into account both the reflector and the core, so that the point kinetics equations, which constitute the theoretical basis of all mathematical development, contemplate both regions of the reactor. From these equations, as known as two regions kinetics point equations, theoretical expressions are obtained for the Auto Power Spectral Densities (APSD), which are used for least squares fit of the experimental data of APSD obtained in several subcritical states. The prompt neutron generation time, the neutron lifetimes in the reflector and the neutron return fraction from the reflector to the core are derived from the fitting. (author)

Optimal design of orientation of PV/T collector with reflectors

International Nuclear Information System (INIS)

Kostic, Lj.T.; Pavlovic, T.M.; Pavlovic, Z.T.

2010-01-01

Hybrid conversion of solar radiation implies simultaneous solar radiation conversion into thermal and electrical energy in the PV/Thermal collector. In order to get more thermal and electrical energy, flat solar radiation reflectors have been mounted on PV/T collector. To obtain higher solar radiation intensity on PV/T collector, position of reflectors has been changed and optimal position of reflectors has been determined by both experimental measurements and numerical calculation so as to obtain maximal concentration of solar radiation intensity. The calculated values have been found to be in good agreement with the measured ones, both yielding the optimal position of the flat reflector to be the lowest (5 o ) in December and the highest (38 o ) in June. In this paper, the thermal and electrical efficiency of PV/T collector without reflectors and with reflectors in optimal position have been calculated. Using these results, the total efficiency and energy-saving efficiency of PV/T collector have been determined. Energy-saving efficiency for PV/T collector without reflectors is 60.1%, which is above the conventional solar thermal collector, whereas the energy-saving efficiency for PV/T collector with reflectors in optimal position is 46.7%, which is almost equal to the values for conventional solar thermal collector. Though the energy-saving efficiency of PV/T collector decreases slightly with the solar radiation intensity concentration factor, i.e. the thermal and electrical efficiency of PV/T collector with reflectors are lower than those of PV/T collector without reflectors, the total thermal and electrical energy generated by PV/T collector with reflectors in optimal position are significantly higher than total thermal and electrical energy generated by PV/T collector without reflectors.

Nonimaging reflectors as functionals of the desired irradiance

International Nuclear Information System (INIS)

Winston, R.; Ries, H.

1993-01-01

For many tasks in illumination and collection the acceptance angle is required to vary along the reflector. If the acceptance angle function is known, then the reflector profile can be calculated as a functional of it. The total flux seen by an observer from a source of uniform brightness (radiance) is proportional to the sum of the view factor of the source and its reflection. This allows one to calculate the acceptance angle function necessary to produce a certain flux distribution and thereby construct the reflector profile. The authors demonstrate the method for several examples, including finite size sources with reflectors directly joining the source

Development and validation of a low-frequency modeling code for high-moment transmitter rod antennas

Science.gov (United States)

Jordan, Jared Williams; Sternberg, Ben K.; Dvorak, Steven L.

2009-12-01

The goal of this research is to develop and validate a low-frequency modeling code for high-moment transmitter rod antennas to aid in the design of future low-frequency TX antennas with high magnetic moments. To accomplish this goal, a quasi-static modeling algorithm was developed to simulate finite-length, permeable-core, rod antennas. This quasi-static analysis is applicable for low frequencies where eddy currents are negligible, and it can handle solid or hollow cores with winding insulation thickness between the antenna's windings and its core. The theory was programmed in Matlab, and the modeling code has the ability to predict the TX antenna's gain, maximum magnetic moment, saturation current, series inductance, and core series loss resistance, provided the user enters the corresponding complex permeability for the desired core magnetic flux density. In order to utilize the linear modeling code to model the effects of nonlinear core materials, it is necessary to use the correct complex permeability for a specific core magnetic flux density. In order to test the modeling code, we demonstrated that it can accurately predict changes in the electrical parameters associated with variations in the rod length and the core thickness for antennas made out of low carbon steel wire. These tests demonstrate that the modeling code was successful in predicting the changes in the rod antenna characteristics under high-current nonlinear conditions due to changes in the physical dimensions of the rod provided that the flux density in the core was held constant in order to keep the complex permeability from changing.

Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

Science.gov (United States)

Vilnrotter, Victor A.

2012-01-01

The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

Integrated reconfigurable multiple-input–multiple-output antenna system with an ultra-wideband sensing antenna for cognitive radio platforms

KAUST Repository

Hussain, Rifaqat; Sharawi, Mohammad S.

2015-01-01

. The developed model can be used as a complete antenna platform for cognitive radio applications. The antenna system is developed on a single substrate area of dimensions 65 × 120 mm². The proposed sensing antenna is used to cover a wide range

Contribution of LPP/ERM-KMS to the modern developments of ICRH antenna systems

Energy Technology Data Exchange (ETDEWEB)

Messiaen, A., E-mail: a.messiaen@fz-juelich.de; Ongena, J.; Dumortier, P.; Durodié, F.; Louche, F.; Ragona, R.; Vervier, M.

2016-11-15

Highlights: • Overview of ICRF antenna coupling physics, showing from first principles how to develop a state of the art ICRF system for ITER and DEMO. • Physics of conceptual solutions for the compact ITER antenna array, intended to radiate ∼10 MW/m2. • Implementing novel ideas into the matching-decoupling network of the ITER antenna array to avoid cross-coupling and to control the RF current distribution in the array. • Experimental tests of the theoretical predictions using scaled mock-ups of the ICRF antenna, including a dielectric dummy load to mimick the plasma. • Demonstrating an operational feedback control of the matching-decoupling network for the ITER antenna array, with 23 simultaneously active actuators. - Abstract: The paper gives an overview of the coupling physics of an ICRF antenna array to the plasma and of the original conceptual solutions proposed by the LPP/ERM-KMS group for the compact ITER antenna array and its matching to the RF power sources. The main contributions are (i) the use of an array of short straps grouped in triplets, (ii) the triplet feed by a four port junction and the use of a service stub to enlarge its frequency response, (iii) the multistep prematching to decrease the VSWR and minimise the voltage in the feeding transmission lines, (iv) the use of a decoupler network to neutralize the mutual coupling effects between different RF power sources and to simultaneously control the current distribution of the antenna array, (v) the various options to connect the decouplers and 3 dB hybrids for different array phasing cases in order to maintain the correct functioning of the decouplers together with load resiliency to fast variations of the plasma density in the edge (caused by e.g. pellet injection or Edge Localized Modes), (vi) the solution of the grounding problem of the ITER antenna plug-in, (vii) the test on mock-ups in front of a dielectric dummy load of the performance of the different solutions and particularly

Temperature Knowledge and Model Correlation for the Soil Moisture Active and Passive (SMAP) Reflector Mesh

Science.gov (United States)

Mikhaylov, Rebecca; Dawson, Douglas; Kwack, Eug

2014-01-01

NASA's Earth observing Soil Moisture Active & Passive (SMAP) Mission is scheduled to launch in November 2014 into a 685 km near-polar, sun synchronous orbit. SMAP will provide comprehensive global mapping measurements of soil moisture and freeze/thaw state in order to enhance understanding of the processes that link the water, energy, and carbon cycles. The primary objectives of SMAP are to improve worldwide weather and flood forecasting, enhance climate prediction, and refine drought and agriculture monitoring during its 3 year mission. The SMAP instrument architecture incorporates an L-band radar and an L-band radiometer which share a common feed horn and parabolic mesh reflector. The instrument rotates about the nadir axis at approximately 15 rpm, thereby providing a conically scanning wide swath antenna beam that is capable of achieving global coverage within 3 days. In order to make the necessary precise surface emission measurements from space, a temperature knowledge of 60 deg C for the mesh reflector is required. In order to show compliance, a thermal vacuum test was conducted using a portable solar simulator to illuminate a non flight, but flight-like test article through the quartz window of the vacuum chamber. The molybdenum wire of the antenna mesh is too fine to accommodate thermal sensors for direct temperature measurements. Instead, the mesh temperature was inferred from resistance measurements made during the test. The test article was rotated to five separate angles between 10 deg and 90 deg via chamber breaks to simulate the maximum expected on-orbit solar loading during the mission. The resistance measurements were converted to temperature via a resistance versus temperature calibration plot that was constructed from data collected in a separate calibration test. A simple thermal model of two different representations of the mesh (plate and torus) was created to correlate the mesh temperature predictions to within 60 deg C. The on-orbit mesh

Optical properties of nonimaging concentrators with corrugated reflectors

Science.gov (United States)

Roennelid, Mats; Perers, Bengt; Karlsson, Bjorn

1994-09-01

A ray tracing study has been performed on the optical properties of cylindrical nonimaging concentrators with linear corrugated reflectors. The corrugations are assumed to be V-formed and to have an extension parallel to the meridian plane of the concentrators. It is shown that the acceptance angle for radiation incident in the meridian plane can be increased for moderate corrugations. This increased acceptance is balanced by a decreased acceptance of radiation from other directions. Calculations of angular acceptance for a 2X compound parabolic concentrator is presented. It is shown that the annual irradiation on a solar collector with booster reflector can be increased if corrugated reflectors are used instead of smooth reflectors.

Telecommunications Antennas for the Juno Mission to Jupiter

Science.gov (United States)

Vacchione, Joseph D.; Kruid, Ronald C.; Prata, Aluizio, Jr.; Amaro, Luis R.; Mittskus, Anthony P.

2012-01-01

The Juno Mission to Jupiter requires a full sphere of coverage throughout its cruise to and mission at Jupiter. This coverage is accommodated through the use of five (5) antennas; forward facing low gain, medium gain, and high gain antennas, and an aft facing low gain antenna along with an aft mounted low gain antenna with a torus shaped antenna pattern. Three of the antennas (the forward low and medium gain antennas) are classical designs that have been employed on several prior NASA missions. Two of the antennas employ new technology developed to meet the Juno mission requirements. The new technology developed for the low gain with torus shaped radiation pattern represents a significant evolution of the bicone antenna. The high gain antenna employs a specialized surface shaping designed to broaden the antenna's main beam at Ka-band to ease the requirements on the spacecraft's attitude control system.

Plasma antennas: dynamically configurable antennas for communications

International Nuclear Information System (INIS)

Borg, G.; Harris, J.

1999-01-01

In recent years, the rapid growth in both communications and radar systems has led to a concomitant growth in the possible applications and requirements of antennas. These new requirements include compactness and conformality, rapid reconfigurability for directionality and frequency agility. For military applications, antennas should also allow low absolute or out-of-band radar cross-section and facilitate low probability of intercept communications. Investigations have recently begun worldwide on the use of ionised gases or plasmas as the conducting medium in antennas that could satisfy these requirements. Such plasma antennas may even offer a viable alternative to metal in existing applications when overall technical requirements are considered. A recent patent for ground penetrating radar claims the invention of a plasma antenna for the transmission of pulses shorter than 100 ns in which it is claimed that current ringing is avoided and signal processing simplified compared with a metal antenna. A recent US ONR tender has been issued for the design and construction of a compact and rapidly reconfigurable antenna for dynamic signal reception over the frequency range 1 - 45 GHz based on plasma antennas. Recent basic physics experiments at ANU have demonstrated that plasma antennas can attain adequate efficiency, predictable radiation patterns and low base-band noise for HF and VHF communications. In this paper we describe the theory of the low frequency plasma antenna and present a few experimental results

Acoustic levitation with self-adaptive flexible reflectors.

Science.gov (United States)

Hong, Z Y; Xie, W J; Wei, B

2011-07-01

Two kinds of flexible reflectors are proposed and examined in this paper to improve the stability of single-axis acoustic levitator, especially in the case of levitating high-density and high-temperature samples. One kind is those with a deformable reflecting surface, and the other kind is those with an elastic support, both of which are self-adaptive to the change of acoustic radiation pressure. High-density materials such as iridium (density 22.6 gcm(-3)) are stably levitated at room temperature with a soft reflector made of colloid as well as a rigid reflector supported by a spring. In addition, the containerless melting and solidification of binary In-Bi eutectic alloy (melting point 345.8 K) and ternary Ag-Cu-Ge eutectic alloy (melting point 812 K) are successfully achieved by applying the elastically supported reflector with the assistance of a laser beam.

Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques

Science.gov (United States)

2017-11-01

on Bio -Inspired Optimization Techniques by Canh Ly, Nghia Tran, and Ozlem Kilic Approved for public release; distribution is...Research Laboratory Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio -Inspired Optimization Techniques by...SUBTITLE Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio -Inspired Optimization Techniques 5a. CONTRACT NUMBER

ICH antenna development on the ORNL RF Test Facility

International Nuclear Information System (INIS)

Gardner, W.L.; Bigelow, T.S.; Haste, G.R.; Hoffman, D.J.; Livesey, R.L.

1987-01-01

A compact resonant loop antenna is installed on the ORNL Radio Frequency Test Facility (RFTF). Facility characteristics include a steady-state magnetic field of ∼ 0.5 T at the antenna, microwave-generated plasmas with n e ∼ 10 12 cm -3 and T e ∼ 8 eV, and 100 kW of 25-MHz rf power. The antenna is tunable from ∼22--75 MHz, is designed to handle ≥1 MW of rf power, and can be moved 5 cm with respect to the port flange. Antenna characteristics reported and discussed include the effect of magnetic field on rf voltage breakdown at the capacitor, the effects of magnetic field and plasma on rf voltage breakdown between the radiating element and the Faraday shield, the effects of graphite on Faraday shield losses, and the efficiency of coupling to the plasma. 2 refs., 4 figs

ICRF antenna and feedthrough development at ORNL

International Nuclear Information System (INIS)

Baity, F.W.; Bryan, W.E.; Hoffman, D.J.; Owens, T.L.; Rettig, C.L.; Schechter, D.E.

1985-01-01

The rf technology program at Oak Ridge National Laboratory is highlighted. Simply stated, the objective of the program is to develop the technology for ion cyclotron range of frequencies heating of the fusion machines leading up to a reactor. Results from an investigation of the importance of current strap shaping in compact antenna design are presented. Designs of the Doublet III-D and Advanced Toroidal Facility compact loop launchers are described, as are the vacuum feedthroughs for the West German tokamak TEXTOR and the Tandem Mirror Experiment Upgrade (TMX-U)

UV dichroic coatings on metallic reflectors

International Nuclear Information System (INIS)

Raghunath, C; Babu, N J; Chandran, K M

2008-01-01

The work presented here explains the design and deposition process of dichroic coating on metallic reflectors developed for UV curing systems. Special designs are adopted to achieve the spectral band and optimized to suit to the requirements. A mirror, which reflects the UV radiation (220 - 400 nm) and absorbs visible and infrared radiation (400 - 2000nm), is described in detail

UV dichroic coatings on metallic reflectors

Energy Technology Data Exchange (ETDEWEB)

Raghunath, C; Babu, N J; Chandran, K M [Hind High Vacuum Co. Pvt. Ltd. No.17, Phase 1, Peenya Industrial Area, Bangalore 560058 (India)

2008-05-01

The work presented here explains the design and deposition process of dichroic coating on metallic reflectors developed for UV curing systems. Special designs are adopted to achieve the spectral band and optimized to suit to the requirements. A mirror, which reflects the UV radiation (220 - 400 nm) and absorbs visible and infrared radiation (400 - 2000nm), is described in detail.

Efficient Placement of Directional Antennas

Energy Technology Data Exchange (ETDEWEB)

Pan, Feng [Los Alamos National Laboratory; Kasiviswanathan, Shiva [Los Alamos National Laboratory

2010-09-20

Directional antenna is an technology for the proliferation of wireless networks. In centralized wireless network, wireless devices communicate through base stations. Directed antennas are placed on base stations and form a backbone of communication. The communication between base stations and wireless devices can be interfered due to a large number of wireless device. Methodically positioning and orienting directed antennas can help to reduce the interference while saving energy. An integer linear programming is developed for siting and directing antennas on multiple base stations, and this formulation can be extended to model non-overlapping channels. Through the integer programming formulation, optimal antenna positions can be used to analyze the performance of directed antennas with different parameters like the number base stations and the number of non-overlapping channels.

Reflector Technology Development and System Design for Concentrating Solar Power Technologies

Energy Technology Data Exchange (ETDEWEB)

Adam Schaut

2011-12-30

Alcoa began this program in March of 2008 with the goal of developing and validating an advanced CSP trough design to lower the levelized cost of energy (LCOE) as compared to existing glass based, space-frame trough technology. In addition to showing a pathway to a significant LCOE reduction, Alcoa also desired to create US jobs to support the emerging CSP industry. Alcoa's objective during Phase I: Concept Feasibility was to provide the DOE with a design approach that demonstrates significant overall system cost savings without sacrificing performance. Phase I consisted of two major tasks; reflector surface development and system concept development. Two specific reflective surface technologies were investigated, silver metallized lamination, and thin film deposition both applied on an aluminum substrate. Alcoa prepared samples; performed test validation internally; and provided samples to the NREL for full-spectrum reflectivity measurements. The final objective was to report reflectivity at t = 0 and the latest durability results as of the completion of Phase 1. The target criteria for reflectance and durability were as follows: (1) initial (t = 0), hemispherical reflectance >93%, (2) initial spectral reflectance >90% for 25-mrad reading and >87% for 7-mrad reading, and (3) predicted 20 year durability of less than 5% optical performance drop. While the results of the reflective development activities were promising, Alcoa was unable to down-select on a reflective technology that met the target criteria. Given the progress and potential of both silver film and thin film technologies, Alcoa continued reflector surface development activities in Phase II. The Phase I concept development activities began with acquiring baseline CSP system information from both CSP Services and the DOE. This information was used as the basis to develop conceptual designs through ideation sessions. The concepts were evaluated based on estimated cost and high-level structural

The Development of LED-Based Dental Light Using a Multiplanar Reflector Design

Directory of Open Access Journals (Sweden)

Chi-Chang Hsieh

2014-01-01

Full Text Available A multiplanar reflector was designed to enhance the application efficiency of light-emitting diode (LED light sources that can be employed as LED-based dental lights. This study used a high-power LED developed by Nichia, that is, a single LED capable of providing a total luminous flux of 120 lm, as the primarily light source to design and develop an LED-based dental light. This LED complies with the international standards and regulations stipulated in ISO 9680:2007. The light spots produced by the prototype were rectangular, with a length of 200 mm and a width of 100 mm. These light spots achieved maximum illumination of 12,000 lux. The use of LEDs can reduce energy consumption from 50 W to 3 W, providing an energy saving of more than 90%.

Enhancement of Solar Water Pasteurization with Reflectors

OpenAIRE

Safapour, Negar; Metcalf, Robert H.

1999-01-01

A simple and reliable method that could be used in developing countries to pasteurize milk and water with solar energy is described. A cardboard reflector directs sunshine onto a black jar, heating water to pasteurizing temperatures in several hours. A reusable water pasteurization indicator verifies that pasteurization temperatures have been reached.

Enhancement of solar water pasteurization with reflectors.

Science.gov (United States)

Safapour, N; Metcalf, R H

1999-02-01

A simple and reliable method that could be used in developing countries to pasteurize milk and water with solar energy is described. A cardboard reflector directs sunshine onto a black jar, heating water to pasteurizing temperatures in several hours. A reusable water pasteurization indicator verifies that pasteurization temperatures have been reached.

Modern lens antennas for communications engineering

CERN Document Server

Thornton, John

2012-01-01

The aim of this book is to present the modern design principles and analysis of lens antennas. It gives graduates and RF/Microwave professionals the design insights in order to make full use of lens antennas.  Why do we want to write a book in lens antennas? Because this topic has not been thoroughly publicized, its importance is underestimated. As antennas play a key role in communication systems, recent development in wireless communications would indeed benefit from the characteristics of lens antennas: low profile, and low cost etc.  The major advantages of lens antennas are na

A Differentially Driven Dual-Polarized Dual-Wideband Complementary Antenna for 2G/3G/LTE Applications

Directory of Open Access Journals (Sweden)

Botao Feng

2014-01-01

Full Text Available A novel differentially driven dual-polarized dual-wideband complementary patch antenna with high isolation is proposed for 2G/3G/LTE applications. In order to generate dual-polarization and dual-wideband properties, a pair of biorthogonal dual-layer η-shaped tapered line feeding structures is utilized to feed two pairs of dual-layer U-shaped patches, respectively. The upper-layer U-shaped patches mainly serve the upper frequency band, while the lower-layer ones chiefly work for the lower frequency band. Besides, a horned reflector is introduced to improve radiation patterns and provide stable gain. The prototype antenna can achieve a bandwidth of 25.7% (0.78 GHz–1.01 GHz with a stable gain of 7.8±0.7 dBi for the lower band, and a bandwidth of 45.7% (1.69 GHz–2.69 GHz with a gain of 9.5±1.1 dBi for the upper band. Input isolation exceeding 30 dB has been obtained in the wide bandwidth. Thus, it can be potentially used as a base station antenna for 2G/3G/LTE networks.

Development of distortion measurement system for large deployable antenna via photogrammetry in vacuum and cryogenic environment

Science.gov (United States)

Zhang, Pengsong; Jiang, Shanping; Yang, Linhua; Zhang, Bolun

2018-01-01

In order to meet the requirement of high precision thermal distortion measurement foraΦ4.2m deployable mesh antenna of satellite in vacuum and cryogenic environment, based on Digital Close-range Photogrammetry and Space Environment Test Technology of Spacecraft, a large scale antenna distortion measurement system under vacuum and cryogenic environment is developed in this paper. The antenna Distortion measurement system (ADMS) is the first domestic independently developed thermal distortion measurement system for large antenna, which has successfully solved non-contact high precision distortion measurement problem in large spacecraft structure under vacuum and cryogenic environment. The measurement accuracy of ADMS is better than 50 μm/5m, which has reached international advanced level. The experimental results show that the measurement system has great advantages in large structural measurement of spacecrafts, and also has broad application prospects in space or other related fields.

Enhancement of Solar Water Pasteurization with Reflectors

Science.gov (United States)

Safapour, Negar; Metcalf, Robert H.

1999-01-01

A simple and reliable method that could be used in developing countries to pasteurize milk and water with solar energy is described. A cardboard reflector directs sunshine onto a black jar, heating water to pasteurizing temperatures in several hours. A reusable water pasteurization indicator verifies that pasteurization temperatures have been reached. PMID:9925631

Circularly polarized antennas

CERN Document Server

Gao, Steven; Zhu, Fuguo

2013-01-01

This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

An Approach for Smart Antenna Testbed

Science.gov (United States)

Kawitkar, R. S.; Wakde, D. G.

2003-07-01

The use of wireless, mobile, personal communications services are expanding rapidly. Adaptive or "Smart" antenna arrays can increase channel capacity through spatial division. Adaptive antennas can also track mobile users, improving both signal range and quality. For these reasons, smart antenna systems have attracted widespread interest in the telecommunications industry for applications to third generation wireless systems.This paper aims to design and develop an advanced antennas testbed to serve as a common reference for testing adaptive antenna arrays and signal combining algorithms, as well as complete systems. A flexible suite of off line processing software should be written using matlab to perform system calibration, test bed initialization, data acquisition control, data storage/transfer, off line signal processing and analysis and graph plotting. The goal of this paper is to develop low complexity smart antenna structures for 3G systems. The emphasis will be laid on ease of implementation in a multichannel / multi-user environment. A smart antenna test bed will be developed, and various state-of-the-art DSP structures and algorithms will be investigated.Facing the soaring demand for mobile communications, the use of smart antenna arrays in mobile communications systems to exploit spatial diversity to further improve spectral efficiency has recently received considerable attention. Basically, a smart antenna array comprises a number of antenna elements combined via a beamforming network (amplitude and phase control network). Some of the benefits that can be achieved by using SAS (Smart Antenna System) include lower mobile terminal power consumption, range extension, ISI reduction, higher data rate support, and ease of integration into the existing base station system. In terms of economic benefits, adaptive antenna systems employed at base station, though increases the per base station cost, can increase coverage area of each cell site, thereby reducing

Development of Radio Frequency Antenna Radiation Simulation Software

International Nuclear Information System (INIS)

Mohamad Idris Taib; Rozaimah Abd Rahim; Noor Ezati Shuib; Wan Saffiey Wan Abdullah

2014-01-01

Antennas are widely used national wide for radio frequency propagation especially for communication system. Radio frequency is electromagnetic spectrum from 10 kHz to 300 GHz and non-ionizing. These radiation exposures to human being have radiation hazard risk. This software was under development using LabVIEW for radio frequency exposure calculation. For the first phase of this development, software purposely to calculate possible maximum exposure for quick base station assessment, using prediction methods. This software also can be used for educational purpose. Some results of this software are comparing with commercial IXUS and free ware NEC software. (author)

Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

Science.gov (United States)

Meador, Mary Ann B.; Miranda, Felix A.

2014-01-01

explored the possibility of developing these arrays in thin, flexible form to make conformable antennas.

Performance of a PV module augmented by a plane reflector

Energy Technology Data Exchange (ETDEWEB)

Ahmad, G. E; Hussein, H. M. S; Mohamad, M. A [Dokki, Giza (Egypt)

2000-07-01

This paper presents a comparative experimental study on the performance of a PV module augmented by a south facing titled plane reflector and another identical one without reflector. The tilt angles of the two PV modules and reflector overhang are selected to be according to a previous theoretical study by the authors. The reflector tilt angle has been changed once a month so that the reflected beams from the plane reflector cover the total surface area of the PV module all days of every month during the high solar radiation period (i.e. three hours before and after solar noon). The study has been carried out on the two PV modules for a complete year under the actual atmospheric conditions of Cairo, Egypt. The measuring system used in the study comprises a data acquisition system, a computer, an electronic load and weather station. The experimental results indicate that the plane reflector enhances the yearly output energy of the PV module y about 22%. [Spanish] Este articulo presenta un estudio comparativo experimental sobre el rendimiento de un modulo de PV aumentado por un reflector plano inclinado mirando hacia el sur y otro identico sin reflector. Los angulos de inclinacion de los dos modulos y el reflector sobresaliente se seleccionan para que esten de acuerdo con un estudio teorico previo hecho por los autores. El angulo de inclinacion del reflector se cambio una vez al mes de manera que los rayos reflejados por el reflector plano cubrieran el area total de la superficie del modulo de PV todos los dias de cada mes durante el periodo de radiacion alto (o sea tres horas antes y despues del medio dia solar). El estudio ha sido llevado a cabo en dos modulos de PV durante un ano completo bajo condiciones atmosfericas reales de El Cairo, Egipto. El sistema de medicion usado en el estudio comprende un sistema de adquisicion de datos, una computadora, una memoria electronica y una estacion climatologica. Los resultados experimentales indican que el reflector plano

Workshop on technology development issues for the large deployable reflector (LDR)

International Nuclear Information System (INIS)

Nishioka, K.

1986-02-01

The results of the 2nd Large Deployable Reflector (LDR) Technology Review Workshop held at Asilomar, California, March 17 to 22, 1985, are summarized. The workshop was convened to update LDR Technology status and to revise as necessary the results for the first LDR Workshop held in June 1982. There were some 100 participants representing government agencies, industry, and universities. This Workshop's goal was to assess, identify, and set priorities for the LDR technology issues based on requirements identified in the first workshop. Four high-priority technology areas were identified: (1) mirror materials and construction; (2) sensing and controls; (3) system-simulation and modeling capability; and (4) submillimeter instruments. The results of the workshop were used to provide a list of technolgy issues for the development of a technology initiatives plan for the LDR by NASA's Office of Aeronautics and Space Technology

Workshop on Technology Development Issues for the Large Deployable Reflector (LDR)

Science.gov (United States)

Nishioka, Kenji (Editor)

1986-01-01

The results of the 2nd Large Deployable Reflector (LDR) Technology Review Workshop held at Asilomar, California, March 17 to 22, 1985, are summarized. The workshop was convened to update LDR Technology status and to revise as necessary the results for the first LDR Workshop held in June 1982. There were some 100 participants representing government agencies, industry, and universities. This Workshop's goal was to assess, identify, and set priorities for the LDR technology issues based on requirements identified in the first workshop. Four high-priority technology areas were identified: (1) mirror materials and construction; (2) sensing and controls; (3) system-simulation and modeling capability; and (4) submillimeter instruments. The results of the workshop were used to provide a list of technolgy issues for the development of a technology initiatives plan for the LDR by NASA's Office of Aeronautics and Space Technology.

Design of LTCC Based Fractal Antenna

KAUST Repository

AdbulGhaffar, Farhan

2010-09-01

The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array has been designed for the first time on Low Temperature Co-fired Ceramic (LTCC) based substrate. LTCC provides a suitable platform for the development of these antennas due to its properties of vertical stack up and embedded passives. The complete antenna concept involves integration of this fractal antenna array with a Fresnel lens antenna providing a total gain of 15dB which is appropriate for medium range radar applications. The thesis also presents a comparison between the designed fractal antenna and a conventional patch antenna outlining the advantages of fractal antenna over the later one. The fractal antenna has a bandwidth of 1.8 GHz which is 7.5% of the centre frequency (24GHz) as compared to 1.9% of the conventional patch antenna. Furthermore the fractal design exhibits a size reduction of 53% as compared to the patch antenna. In the end a sensitivity analysis is carried out for the fractal antenna design depicting the robustness of the proposed design against the typical LTCC fabrication tolerances.

49 CFR 393.26 - Requirements for reflectors.

Science.gov (United States)

2010-10-01

... case of motor vehicles so constructed that requirement for a 381 mm (15-inch) minimum height above the... used in lieu of reflex reflectors if the material as used on the vehicle, meets the performance... motor vehicle. (3) Such surfaces shall be at least 3 inches from any required lamp or reflector unless...

Structured surface reflector design for oblique incidence beam splitter at 610 GHz

OpenAIRE

Defrance , Fabien; Casaletti , Massimiliano; Sarrazin , Julien; Wiedner , Martina; Gibson , Hugh; Gay , Gregory; Lefevre , Roland; Delorme , Yan

2016-01-01

International audience; An iterative alternate projection-based algorithm is developed to design structured surface reflectors to operate as beam splitters at GHz and THz frequencies. To validate the method, a surface profile is determined to achieve a reflector at 610 GHz that generates four equal-intensity beams towards desired directions of ±12.6° with respect to the specular reflection axis. A prototype is fabricated and the beam splitter behavior is experimentally demonstrated. Measureme...

Optimization of MNSR upper reflector material and dimensions

International Nuclear Information System (INIS)

Albarhoum, M.

2007-04-01

Calculations for the optimization of the material and dimensions of the Syrian MNSR was performed. Calculations showed that the considerably important reflectors in this case are Beryllium, Heavy water and Graphite. Dimensions of the reflector cannot any way exceed the Shim Tray dimensions. Two different ways of filling the Shim Tray with the reflector material were established: 1- the radial filling mode, and 2- the axial mode. Both modes can be performed using single sectors or cumulative ones. The axial mode proved to be better than the radial one. The axial cumulative mode proved to be more efficient than the single axial one. The axial cumulative mode was studied from two points of view; the neutronic and the economic ones. From the neutronic point of view the beryllium proved to be the best reflector, and the best dimensions were found to coincide with a thickness equal to 0.11235 cm with the bottom end being 0.4494 cm distant from the bottom of the Shim Tray. From the economic point of view it was found that the cost of the reactivity unit is the smallest when the Graphite is used. Results of this study can be applied directly to the Syrian MNSR since fabrication of any plastic containment for the reflector can easily be achieved. This is because the reactivity worth resulting from mass unit of the reflector varies depending on its position positions in the Shim Tray.(author)

Reflector automatic acquisition and pointing based on auto-collimation theodolite

Science.gov (United States)

Luo, Jun; Wang, Zhiqian; Wen, Zhuoman; Li, Mingzhu; Liu, Shaojin; Shen, Chengwu

2018-01-01

An auto-collimation theodolite (ACT) for reflector automatic acquisition and pointing is designed based on the principle of autocollimators and theodolites. First, the principle of auto-collimation and theodolites is reviewed, and then the coaxial ACT structure is developed. Subsequently, the acquisition and pointing strategies for reflector measurements are presented, which first quickly acquires the target over a wide range and then points the laser spot to the charge coupled device zero position. Finally, experiments are conducted to verify the acquisition and pointing performance, including the calibration of the ACT, the comparison of the acquisition mode and pointing mode, and the accuracy measurement in horizontal and vertical directions. In both directions, a measurement accuracy of ±3″ is achieved. The presented ACT is suitable for automatic pointing and monitoring the reflector over a small scanning area and can be used in a wide range of applications such as bridge structure monitoring and cooperative target aiming.

Hybrid integrated single-wavelength laser with silicon micro-ring reflector

Science.gov (United States)

Ren, Min; Pu, Jing; Krishnamurthy, Vivek; Xu, Zhengji; Lee, Chee-Wei; Li, Dongdong; Gonzaga, Leonard; Toh, Yeow T.; Tjiptoharsono, Febi; Wang, Qian

2018-02-01

A hybrid integrated single-wavelength laser with silicon micro-ring reflector is demonstrated theoretically and experimentally. It consists of a heterogeneously integrated III-V section for optical gain, an adiabatic taper for light coupling, and a silicon micro-ring reflector for both wavelength selection and light reflection. Heterogeneous integration processes for multiple III-V chips bonded to an 8-inch Si wafer have been developed, which is promising for massive production of hybrid lasers on Si. The III-V layer is introduced on top of a 220-nm thick SOI layer through low-temperature wafer-boning technology. The optical coupling efficiency of >85% between III-V and Si waveguide has been achieved. The silicon micro-ring reflector, as the key element of the hybrid laser, is studied, with its maximized reflectivity of 85.6% demonstrated experimentally. The compact single-wavelength laser enables fully monolithic integration on silicon wafer for optical communication and optical sensing application.

A revolutionary concept to improve the efficiency of IC antennas

Energy Technology Data Exchange (ETDEWEB)

Milanesio, D.; Maggiora, R. [Politecnico di Torino, Dipartimento di Elettronica e Telecomunicazioni (DET), Torino (Italy)

2014-02-12

The successful design of an Ion Cyclotron (IC) antenna mainly relies on the capability of coupling high power to the plasma (MW), feature that is currently reached by allowing rather high voltages (tens of kV) on the unavoidable unmatched part of the feeding lines. This requirement is often responsible of arcs along the transmission lines and other unwanted phenomena that considerably limit the usage of IC launchers. In this work, we suggest and describe a revolutionary approach based on high impedance surfaces, which allows to increase the antenna radiation efficiency and, hence, to highly reduce the imposed voltages to couple the same level of power to the plasma. High-impedance surfaces are periodic metallic structures (patches) displaced usually on top of a dielectric substrate and grounded by means of vertical posts usually embedded inside a dielectric, in a mushroom-like shape. In terms of working properties, high impedance surfaces are electrically thin in-phase reflectors, i.e. they present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. While the usual design of a high impedance surface requires the presence of a dielectric layer, some alternative solutions can be realized in vacuum, taking advantage of double layers ofmetallic patches. After an introductory part on the properties of high impedance surfaces, this work documents both their design by means of numerical codes and their implementation on a scaled mock-up.

User manual for semi-circular compact range reflector code: Version 2

Science.gov (United States)

Gupta, Inder J.; Burnside, Walter D.

1987-01-01

A computer code has been developed at the Ohio State University ElectroScience Laboratory to analyze a semi-circular paraboloidal reflector with or without a rolled edge at the top and a skirt at the bottom. The code can be used to compute the total near field of the reflector or its individual components at a given distance from the center of the paraboloid. The code computes the fields along a radial, horizontal, vertical or axial cut at that distance. Thus, it is very effective in computing the size of the sweet spot for a semi-circular compact range reflector. This report describes the operation of the code. Various input and output statements are explained. Some results obtained using the computer code are presented to illustrate the code's capability as well as being samples of input/output sets.

Deployable reflector configurations

Science.gov (United States)

Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

Design and development of a lower-hybrid antenna for the MST reversed field pinch

International Nuclear Information System (INIS)

Thomas, M.; Cekic, M.; Lovell, T.W.; Prager, S.C.; Sarff, J.S.; Uchimoto, E.

1995-01-01

Recent theoretical studies strongly motivated the development of a radio-frequency current drive scheme for current density gradient reduction in the outer region of a reversed field pinch. The preliminary experiments using inductive current drive indicate that such current density profile modification reduces the magnetic fluctuation amplitude and related energy and particle losses. To test the theoretical predictions and to further improve confinement in the MST, the authors are planning a series of lower-hybrid wave experiments. The initial phase is the design and optimization of a low-power antenna to study slow wave propagation in a frequency range 2--3 f LH (200--300 MHz) with parallel index of refraction n parallel ∼10. Ray-tracing calculations, for typical MST plasma parameters, indicate that such a wave will spiral radially into a target zone inside the reversal layer. The antenna consists of an array of tunable loops arranged in the poloidal direction. The design is compatible with the existing box-port openings in the MST conductive shell to prevent additional magnetic field errors associated with large portholes. Antenna vacuum characteristics are studied on a test-stand designed to approximate the geometry of the MST shell. For the initial measurements of plasma response and antenna loading, the authors designed a reduced, easily insertable, vacuum antenna structure. The results of plasma impedance measurements will be compared with the numerical modeling results and incorporated in the optimized design of the antenna for wave propagation experiments

Laser reflector with an interference coating

International Nuclear Information System (INIS)

Vol'pyan, O D; Semenov, A A; Yakovlev, P P

1998-01-01

An analysis was made of the reflectivity of interference coatings intended for the use in optical pumping of solid-state lasers. Ruby and Nd 3+ :YAG lasers were used as models in comparative pumping efficiency measurements, carried out employing reflectors with interference and silver coatings. Estimates of the service life of reflectors with interference coatings were obtained. The power of a thermo-optical lens was reduced by the use of such coatings in cw lasers. (laser system components)

Disordered animal multilayer reflectors and the localization of light

Science.gov (United States)

Jordan, T. M.; Partridge, J. C.; Roberts, N. W.

2014-01-01

Multilayer optical reflectors constructed from ‘stacks’ of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered ‘coloured’ and more strongly disordered ‘silvery’ reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine–cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity. PMID:25339688

Smart Antenna UKM Testbed for Digital Beamforming System

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH array antenna and software reconfigurable digital beamforming system (DBS. The antenna is developed based on using the novel LIEH microstrip patch element design arranged into 4×1 uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance TMS320C6711TM floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88–2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.

Development and evaluation of a boat-mounted RFID antenna for monitoring freshwater mussels

Science.gov (United States)

Fischer, Jesse R.; Neebling, Travis E.; Quist, Michael C.

2012-01-01

Development of radio frequency identification (RFID) technology and passive integrated transponder (PIT) tags has substantially increased the ability of researchers and managers to monitor populations of aquatic organisms. However, use of transportable RFID antenna systems (i.e., backpack-mounted) is currently limited to wadeable aquatic environments (system regardless of tag orientation. However, burrowed mussels may require multiple passes to increase detection that would be influenced by depth, tag orientation, and tag size. Construction of the boat-mounted antenna was relatively low in cost (traditional mussel sampling techniques (diving, snorkeling) in nonwadeable habitats.

A Modal Approach to Compact MIMO Antenna Design

Science.gov (United States)

Yang, Binbin

MIMO (Multiple-Input Multiple-Output) technology offers new possibilities for wireless communication through transmission over multiple spatial channels, and enables linear increases in spectral efficiency as the number of the transmitting and receiving antennas increases. However, the physical implementation of such systems in compact devices encounters many physical constraints mainly from the design of multi-antennas. First, an antenna's bandwidth decreases dramatically as its electrical size reduces, a fact known as antenna Q limit; secondly, multiple antennas closely spaced tend to couple with each other, undermining MIMO performance. Though different MIMO antenna designs have been proposed in the literature, there is still a lack of a systematic design methodology and knowledge of performance limits. In this dissertation, we employ characteristic mode theory (CMT) as a powerful tool for MIMO antenna analysis and design. CMT allows us to examine each physical mode of the antenna aperture, and to access its many physical parameters without even exciting the antenna. For the first time, we propose efficient circuit models for MIMO antennas of arbitrary geometry using this modal decomposition technique. Those circuit models demonstrate the powerful physical insight of CMT for MIMO antenna modeling, and simplify MIMO antenna design problem to just the design of specific antenna structural modes and a modal feed network, making possible the separate design of antenna aperture and feeds. We therefore develop a feed-independent shape synthesis technique for optimization of broadband multi-mode apertures. Combining the shape synthesis and circuit modeling techniques for MIMO antennas, we propose a shape-first feed-next design methodology for MIMO antennas, and designed and fabricated two planar MIMO antennas, each occupying an aperture much smaller than the regular size of lambda/2 x lambda/2. Facilitated by the newly developed source formulation for antenna stored

Development and evaluation of a boat-mounted RFID antenna for monitoring freshwater mussels

Science.gov (United States)

Fischer, Jesse R.; Neebling, Travis E.; Quist, Michael C.

2012-01-01

Development of radio frequency identification (RFID) technology and passive integrated transponder (PIT) tags has substantially increased the ability of researchers and managers to monitor populations of aquatic organisms. However, use of transportable RFID antenna systems (i.e., backpack-mounted) is currently limited to wadeable aquatic environments (RFID antenna to detect individually PIT-tagged benthic aquatic organisms (mussels). We evaluated the effects of tag orientation on detection distances in water with a 32-mm half-duplex PIT tag. Detection distances up to 50 cm from the antenna coils were obtained, but detection distance was dependent on tag orientation. We also evaluated detection distance of PIT tags beneath the sediment to simulate detection of burrowing mussels with 23- and 32-mm tags. In sand substrate, the maximum detection distance varied from 3.5 cm and 4.5 cm (vertical tag orientation) to 24.7 cm and 39.4 cm (45° tag orientation) for the 23- and 32-mm PIT tags, respectively. Our results suggest a 1.4-m total detection width for tagged mussels on the substrate surface by the boat-mounted antenna system regardless of tag orientation. However, burrowed mussels may require multiple passes to increase detection that would be influenced by depth, tag orientation, and tag size. Construction of the boat-mounted antenna was relatively low in cost (<500 USD) and had several advantages (less labor and time intensive, increased safety) over traditional mussel sampling techniques (diving, snorkeling) in nonwadeable habitats.

Full reflector thickness and isolation thickness on neutron transport

International Nuclear Information System (INIS)

Sakai, Tomohiro; Naito, Yoshitaka; Komuro, Yuichi.

1988-08-01

A method to determine ''full reflector thickness'' and ''isolation thickness'', which is utilized for criticality safety evaluation on nuclear fuel facilities, was proposed in this paper. Firstly, a calculation was tryed to obtain the two kinds of thicknesses from the result of criticality calculations for a specific case. Then, two simple equations which calculates the two kinds of thicknesses were made from the relation between reflector (or isolator) thickness and k eff , and one-group diffusion theory. Finally, we proposed a new method to determine the thicknesses. From the method we proposed, ''full reflector thickness'' and ''isolation thickness'' can be obtain using the equations and migration length of the reflector (or isolator) and infinite and effective multiplication factor of the fuel. (author)

Experimental Evaluation of Optically Polished Aluminum Panels on the Deep Space Network's 34 Meter Antenna

Science.gov (United States)

Vilnrotter, V.

2011-01-01

The potential development of large aperture ground?based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation is to polish the aluminum reflector panels of 34?meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by state of?the?art polished aluminum panels. Theoretical analyses of receiving antenna pointing, temporal synchronization and data detection have been addressed in previous papers. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. Two polished aluminum panels (a standard DSN panel polished to high reflectance, and a custom designed aluminum panel with much better surface quality) have been mounted on the 34 meter research antenna at Deep?Space Station 13 (DSS?13), and a remotely controlled CCD camera with a large CCD sensor in a weather?proof container has been installed next to the subreflector, pointed directly at the custom polished panel. The point?spread function (PSF) generated by the Vertex polished panel has been determined to be smaller than the sensor of the CCD camera, hence a detailed picture of the PSF can be obtained every few seconds, and the sensor array data processed to determine the center of the intensity distribution. In addition to estimating the center coordinates, expected communications performance can also been evaluated with the recorded data. The results of preliminary pointing experiments with the Vertex polished panel receiver using the planet Jupiter to simulate the PSF generated by a deep?space optical transmitter are presented and discussed in this paper.

Ray Tracing modelling of reflector for vertical bifacial panel

DEFF Research Database (Denmark)

Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

2016-01-01

Bifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose a reflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, we investigate the impact of the reflector volume being filled...... with a refractive medium, and shows the refractive medium improves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel....

Simulation study of resonant reflector for S-band BWO

International Nuclear Information System (INIS)

Choyal, Y; Parmar, Nidhi; Saini, Ajay Kumar; Chhotray, S K; Bhat, K S; Kumar, Lalit

2012-01-01

This paper presents the result of simulation studies of resonant reflector used for reflection of backward wave in relativistic BWO. The resonant reflector is modelled and analyzed by CST MWS for TM 01 . A TM 01 mode is fed at the output end of the BWO and signal is observed at the cathode end. Results show that 90 percent of the backward TM 01 wave is get reflected back by the locked TM 02 mode in the resonant reflector.

Bandwidth Study of the Microwave Reflectors with Rectangular Corrugations

Science.gov (United States)

Zhang, Liang; He, Wenlong; Donaldson, Craig R.; Cross, Adrian W.

2016-09-01

The mode-selective microwave reflector with periodic rectangular corrugations in the inner surface of a circular metallic waveguide is studied in this paper. The relations between the bandwidth and reflection coefficient for different numbers of corrugation sections were studied through a global optimization method. Two types of reflectors were investigated. One does not consider the phase response and the other does. Both types of broadband reflectors operating at W-band were machined and measured to verify the numerical simulations.

Infrared diffractive filtering for extreme ultraviolet multilayer Bragg reflectors

NARCIS (Netherlands)

Medvedev, Viacheslav; van den Boogaard, Toine; van der Meer, R.; Yakshin, Andrey; Louis, Eric; Krivtsun, V.M.; Bijkerk, Frederik

2013-01-01

Abstract: We report on the development of a hybrid mirror realized by integrating an EUV-reflecting multilayer coating with a lamellar grating substrate. This hybrid irror acts as an efficient Bragg reflector for extreme ultraviolet (EUV) radiation at a given wavelength while simultaneously

Multiband Photonic Phased-Array Antenna

Science.gov (United States)

Tang, Suning

2015-01-01

A multiband phased-array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. Crystal Research, Inc., has developed a multiband photonic antenna that is based on a high-speed, optical, true-time-delay beamformer. It is capable of simultaneously steering multiple independent radio frequency (RF) beams in less than 1,000 nanoseconds. This high steering speed is 3 orders of magnitude faster than any existing optical beamformer. Unlike other approaches, this technology uses a single controlling device per operation band, eliminating the need for massive optical switches, laser diodes, and fiber Bragg gratings. More importantly, only one beamformer is needed for all antenna elements.

Inflatable Antennas Support Emergency Communication

Science.gov (United States)

2010-01-01

Glenn Research Center awarded Small Business Innovation Research (SBIR) contracts to ManTech SRS Technologies, of Newport Beach, California, to develop thin film inflatable antennas for space communication. With additional funding, SRS modified the concepts for ground-based inflatable antennas. GATR (Ground Antenna Transmit and Receive) Technologies, of Huntsville, Alabama, licensed the technology and refined it to become the world s first inflatable antenna certified by the Federal Communications Commission. Capable of providing Internet access, voice over Internet protocol, e-mail, video teleconferencing, broadcast television, and other high-bandwidth communications, the systems have provided communication during the wildfires in California, after Hurricane Katrina in Mississippi, and following the 2010 Haiti earthquake.

Review of Large Spacecraft Deployable Membrane Antenna Structures

Science.gov (United States)

Liu, Zhi-Quan; Qiu, Hui; Li, Xiao; Yang, Shu-Li

2017-11-01

The demand for large antennas in future space missions has increasingly stimulated the development of deployable membrane antenna structures owing to their light weight and small stowage volume. However, there is little literature providing a comprehensive review and comparison of different membrane antenna structures. Space-borne membrane antenna structures are mainly classified as either parabolic or planar membrane antenna structures. For parabolic membrane antenna structures, there are five deploying and forming methods, including inflation, inflation-rigidization, elastic ribs driven, Shape Memory Polymer (SMP)-inflation, and electrostatic forming. The development and detailed comparison of these five methods are presented. Then, properties of membrane materials (including polyester film and polyimide film) for parabolic membrane antennas are compared. Additionally, for planar membrane antenna structures, frame shapes have changed from circular to rectangular, and different tensioning systems have emerged successively, including single Miura-Natori, double, and multi-layer tensioning systems. Recent advances in structural configurations, tensioning system design, and dynamic analysis for planar membrane antenna structures are investigated. Finally, future trends for large space membrane antenna structures are pointed out and technical problems are proposed, including design and analysis of membrane structures, materials and processes, membrane packing, surface accuracy stability, and test and verification technology. Through a review of large deployable membrane antenna structures, guidance for space membrane-antenna research and applications is provided.

Nonimaging compound parabolic concentrator-type reflectors with variable extreme direction.

Science.gov (United States)

Gordon, J M; Rabl, A

1992-12-01

The properties of nonimaging compound parabolic concentrator (CPC)-type devices are examined in which the extreme direction is not constant but rather is a variable that can change along the reflector. One can then retain the maximal concentration or radiative efficiency of the CPC while the flux map on the absorber or target is modified, depending on whether the device is used for optical concentration or for lighting. Two general classes of reflector are derived, and all the nonimaging devices developed to date are shown to be special cases of the general solution. These two classes are the nonimaging analog of converging and diverging devices of imaging optics.

Design and Optimization of Passive UHF RFID Tag Antenna for Mounting on or inside Material Layers

Science.gov (United States)

Shao, Shuai

proximity and designing broad band and mechanically robust RFID tag antennas for elastic materials. As a first step, the effects of dielectric materials on an antenna's impedance match and radiation pattern are investigated. The detuning effect is quantified based on the theoretical frequency scaling and effective permittivity of a dielectric material of finite thickness. Using simple formulas, the operational range of a tag can be predicted without intensive full-wave simulations of different materials. Next, a spectral domain Green's function is applied to compute the antenna pattern when the tag is mounted on or inside a layered medium. The optimal placement of the tag is found based on the focusing effect that the material has on the gain pattern of the antenna. For tires, the steel ply in the sidewall of a tire looks like a periodic wire grating. The performance of an antenna placed close to a wire grating is predicted using Floquet theory. The results indicate that steel plies embedded in the tire can be utilized as a reflector to further focus the gain pattern and increase the read range of a tag. Using these design tools and theoretical analysis, several broadband RFID tag antennas are designed for multi-layered materials. A novel stretchable conductive textile (E-fiber) based tag antenna is also developed for placement in elastic materials. Prototype antennas are fabricated and embedded in a tire during the tire manufacturing process. Experimental results indicate that tags with the new antennas achieve significant improvement compared with commercially available tags.

Development of Electromagnetic Band Gap Structures in the Perspective of Microstrip Antenna Design

Directory of Open Access Journals (Sweden)

Md. Shahidul Alam

2013-01-01

Full Text Available Electromagnetic band gap (EBG technology has become a significant breakthrough in the radio frequency (RF and microwave applications due to their unique band gap characteristics at certain frequency ranges. Since 1999, the EBG structures have been investigated for improving performances of numerous RF and microwave devices utilizing the surface wave suppression and the artificial magnetic conductor (AMC properties of these special type metamaterial. Issues such as compactness, wide bandwidth with low attenuation level, tunability, and suitability with planar circuitry all play an important role in the design of EBG structures. Remarkable efforts have been undertaken for the development of EBG structures to be compatible with a wide range of wireless communication systems. This paper provides a comprehensive review on various EBG structures such as three-, two-, and one-dimensional (3D, 2D, and 1D EBG, mushroom and uniplanar EBG, and their successive advancement. Considering the related fabrication complexities, implementation of vialess EBG is an attractive topic for microwave engineers. For microstrip antennas, EBG structures are used in diversified ways, which of course found to be effective except in some cases. The EBG structures are also successfully utilized in antenna arrays for reducing the mutual coupling between elements of the array. Current challenges and limitations of the typical microstrip antennas and different EBG structures are discussed in details with some possible suggestions. Hopefully, this survey will guide to increasing efforts towards the development of more compact, wideband, and high-efficient uniplanar EBG structures for performance enhancement of antenna and other microwave devices.

Neutron spectrum in small iron pile surrounded by lead reflector

International Nuclear Information System (INIS)

Kimura, Itsuro; Hayashi, S.A.; Kobayashi, Katsuhei; Matsumura, Tetsuo; Nishihara, Hiroshi.

1978-01-01

In order to save the quantity of sample material, a possibility to assess group constants of a reactor material through measurement and analysis of neutron spectrum in a small sample pile surrounded by a reflector of heavy moderator, was investigated. As the sample and the reflector, we chose iron and lead, respectively. Although the time dispersion in moderation of neutrons was considerably prolonged by the lead reflector, this hardly interferes with the assessment of group constants. Theoretical calculation revealed that both the neutron flux spectrum and the sensitivity coefficient of group constants in an iron sphere, 35 cm in diameter surrounded by the lead reflector, 25 cm thick, were close to those of the bare iron sphere, 108 cm in diameter. The neutron spectra in a small iron pile surrounded by a lead reflector were experimentally obtained by the time-of-flight method with an electron linear accelerator and the result was compared with the predicted values. It could be confirmed that a small sample pile surrounded by a reflector, such as lead, was as useful as a much larger bulk pile for the assessment of group constants of a reactor material. (auth.)

Ultrabroadband Hybrid III-V/SOI Grating Reflector for On-chip Lasers

DEFF Research Database (Denmark)

Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

2016-01-01

We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability.......We report on a new type of III-V/SOI grating reflector with a broad stopband of 350 nm. This reflector has promising prospects for applications in high-speed III-V/SOI vertical cavity lasers with an improved heat dissipation capability....

Development of a fishbone travelling wave antenna for LHD

International Nuclear Information System (INIS)

Takase, Y.; Ejiri, A.; Shiraiwa, S.

2002-10-01

A travelling wave antenna in the ion cyclotron range of frequencies (ICRF) is being developed for LHD, motivated by the need to provide a capability for rotational transform profile control by noninductively driven current. Stability calculations suggest that it is possible to increase the beta limit and obtain access to the second stability regime by controlling the rotational transform profile. Current drive by the ICRF fast wave (magnetosonic wave) can be used for such a purpose. (author)

Equipment: Antenna systems

Science.gov (United States)

Petrie, L. E.

1986-03-01

Some antenna fundamentals as well as definitions of the principal terms used in antenna engineering are described. Methods are presented for determining the desired antenna radiation patterns for HF communication circuit or service area. Sources for obtaining or computing radiation pattern information are outlined. Comparisons are presented between the measured and computed radiation patterns. The effect of the properties of the ground on the antenna gain and the pattern are illustrated for several types of antennas. Numerous examples are given of the radiation patterns for typical antennas used on short, intermediate and long distance circuits for both mobile and fixed service operations. The application of adaptive antenna arrays and active antennas in modern HF communication systems are briefly reviewed.

Convergence studies of deterministic methods for LWR explicit reflector methodology

International Nuclear Information System (INIS)

Canepa, S.; Hursin, M.; Ferroukhi, H.; Pautz, A.

2013-01-01

The standard approach in modem 3-D core simulators, employed either for steady-state or transient simulations, is to use Albedo coefficients or explicit reflectors at the core axial and radial boundaries. In the latter approach, few-group homogenized nuclear data are a priori produced with lattice transport codes using 2-D reflector models. Recently, the explicit reflector methodology of the deterministic CASMO-4/SIMULATE-3 code system was identified to potentially constitute one of the main sources of errors for core analyses of the Swiss operating LWRs, which are all belonging to GII design. Considering that some of the new GIII designs will rely on very different reflector concepts, a review and assessment of the reflector methodology for various LWR designs appeared as relevant. Therefore, the purpose of this paper is to first recall the concepts of the explicit reflector modelling approach as employed by CASMO/SIMULATE. Then, for selected reflector configurations representative of both GII and GUI designs, a benchmarking of the few-group nuclear data produced with the deterministic lattice code CASMO-4 and its successor CASMO-5, is conducted. On this basis, a convergence study with regards to geometrical requirements when using deterministic methods with 2-D homogenous models is conducted and the effect on the downstream 3-D core analysis accuracy is evaluated for a typical GII deflector design in order to assess the results against available plant measurements. (authors)

Sensitivity analysis of reflector types and impurities in 10 MW MTR type nuclear research reactor

International Nuclear Information System (INIS)

Khattab, K.; Khamis, I.

2007-01-01

The 2-D and 3-D neutronics models for 10 MW nuclear research reactor of MTR type have been developed and presented in this paper. Our results agree very well with the results of seven countries mentioned in the IAEA-TECDOC-233. To study the effect of reflector types on the reactor effective multiplication factor, five types of reflectors such as pure beryllium, beryllium, heavy water, carbon and water are selected for this study. The pure beryllium is found to be the most efficient reflector in this group. The effect of the most important impurities, which exist on the beryllium reflector such as iron, silicon and aluminium on the reactor multiplication factor, have been analyzed as well. It is found that the iron impurity affects the reactor multiplication factor the most compared to silicon and aluminium impurities. (author)

A Nonlinear Dynamic Model and Free Vibration Analysis of Deployable Mesh Reflectors

Science.gov (United States)

Shi, H.; Yang, B.; Thomson, M.; Fang, H.

2011-01-01

This paper presents a dynamic model of deployable mesh reflectors, in which geometric and material nonlinearities of such a space structure are fully described. Then, by linearization around an equilibrium configuration of the reflector structure, a linearized model is obtained. With this linearized model, the natural frequencies and mode shapes of a reflector can be computed. The nonlinear dynamic model of deployable mesh reflectors is verified by using commercial finite element software in numerical simulation. As shall be seen, the proposed nonlinear model is useful for shape (surface) control of deployable mesh reflectors under thermal loads.

Design and Development of Compact Microstrip Patch Antenna for Wireless Applications

Directory of Open Access Journals (Sweden)

R. Nagendra

2017-09-01

Full Text Available In this paper, a novel dual band microstrip patch antenna based on composite patch antenna and radiating part. By selecting a suitable offset feed position, it is feasible to provide 50Ω characteristic impedance and thus making better impedance matching. The proposed antenna has been improved broader bandwidth by using RT Duroid substrate. The radiating part is plays a important role in creating a lower operating band (2.45 GHz in addition to achieve miniaturization. The proposed antenna has to be fabricated with RT / Duroid substrate and dimensions of 19 × 22 × 0.8 mm. The measured -10 dB bandwidth of 200 MHz at 2.45 GHz and 990 MHz at 5.45 GHz, which is quite useful for Industrial, Scientific and Medical (ISM and WLAN applications.

Feasibility study of fusion breeding blanket concept employing graphite reflector

International Nuclear Information System (INIS)

Cho, Seungyon; Ahn, Mu-Young; Lee, Cheol Woo; Kim, Eung Seon; Park, Yi-Hyun; Lee, Youngmin; Lee, Dong Won

2015-01-01

Highlights: • A Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept adopts graphite as a reflector material by reducing the amount of beryllium multiplier. • Its feasibility was investigated in view point of the nuclear performance as well as material-related issues. • A nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket. • Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions. • In conclusion, the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition. - Abstract: To obtain high tritium breeding performance with limited blanket thickness, most of solid breeder blanket concepts employ a combination of lithium ceramic as a breeder and beryllium as a multiplier. In this case, considering that huge amount of beryllium are needed in fusion power plants, its handling difficulty and cost can be a major factor to be accounted for commercial use. Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. Its feasibility has been investigated in view point of the nuclear performance as well as material-related issues. In this paper, a nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket, considering tritium breeding capability and neutron shielding and activation aspects. Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions, resulting in that the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition.

Feasibility study of fusion breeding blanket concept employing graphite reflector

Energy Technology Data Exchange (ETDEWEB)

Cho, Seungyon, E-mail: sycho@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Ahn, Mu-Young [National Fusion Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Woo; Kim, Eung Seon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Yi-Hyun; Lee, Youngmin [National Fusion Research Institute, Daejeon (Korea, Republic of); Lee, Dong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

Highlights: • A Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept adopts graphite as a reflector material by reducing the amount of beryllium multiplier. • Its feasibility was investigated in view point of the nuclear performance as well as material-related issues. • A nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket. • Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions. • In conclusion, the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition. - Abstract: To obtain high tritium breeding performance with limited blanket thickness, most of solid breeder blanket concepts employ a combination of lithium ceramic as a breeder and beryllium as a multiplier. In this case, considering that huge amount of beryllium are needed in fusion power plants, its handling difficulty and cost can be a major factor to be accounted for commercial use. Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. Its feasibility has been investigated in view point of the nuclear performance as well as material-related issues. In this paper, a nuclear analysis is performed under the fusion reactor condition to address the feasibility of graphite reflector in breeding blanket, considering tritium breeding capability and neutron shielding and activation aspects. Also, the chemical stability of the graphite is investigated considering the chemical stability under accident conditions, resulting in that the adaptation of graphite reflector in breeding blanket is intrinsically safe and plausible under fusion reactor condition.

Study of the Effect of Simulated Rain on the Offset Parabolic Antenna at Ku-Band with Different Elevation Angles

Directory of Open Access Journals (Sweden)

H. Mostafa

2007-01-01

Full Text Available Effect of rain on the receiver antenna is a major factor to degrade the system performance in a frequency above 10 GHz. This paper deals with the wet antenna attenuation at Ku-band with three different frequencies at different rain rates. During the Ku-band propagation experiment, it was discovered that rain water on the antenna caused a significant attenuation. It is necessary to estimate the losses caused by water on the antenna in order to separate these losses from the atmospheric propagation losses. The experiment was done at USM Engineering Campus to study the attenuation for these physical parameters. A Ku-band RF signal was generated by a signal generator and transmitted via horn antenna. The signal was received using a smooth offset antenna of 60 cm by 54 cm (Astro dish and measured using spectrum analyzer. In order to simulate a rain, pipes with bores of a same distance were implemented. Three cases were considered: in the first case one pipe was used to simulate low rain rate, the second case two pipes were used to simulate medium rain rate, and the third case three pipes were used to simulate heavy rain rate. In addition, the tap was used to control the flow of water in order to get more values of rain rate. The total attenuation of RF signals due to water layer on the feed and on the reflector feed was found to be 3.1 dB at worst case. On the other hand, the attenuation of RF signal due to the feed only was 2.83 dB, so the major attenuation occur was due to feed.

ANALISIS PERBANDINGAN OUTPUT DAYA LISTRIK PANEL SURYA SISTEM TRACKING DENGAN SOLAR REFLECTOR

Directory of Open Access Journals (Sweden)

I B Kd Surya Negara

2016-03-01

Full Text Available Indonesia merupakan negara beriklim tropis yang memiliki intensitas radiasi matahari yang sangat besar dan intensitas radiasi tersebut berpotensi untuk dikembangkan menjadi Pembangkit Listrik Tenaga Surya. Efisiensi dari panel surya saat ini masih perlu pertimbangan lebih lanjut. Efisiensi panel surya yang rendah ini, berpengaruh pada hasil output daya listrik yang dihasilkan. Upaya untuk meningkatkan output daya listrik panel surya, yaitu dengan sistem tracking dan solar reflector. Penelitian ini bertujuan untuk mengetahui output daya listrik yang lebih maksimal. Metode dalam penelitian ini menggunakan sistem tracking yang pergerakannya berdasarkan waktu dan menggunakan solar reflector dengan cermin datar dan sudut reflector yang berbeda. Hasil dari perbandingan sistem tracking dengan solar reflector yaitu solar reflector menghasilkan output daya listrik lebih besar dibandingan dengan sistem tracking, dimana solar reflector menghasilkan output daya listrik sebesar 0.1224 Watt dan sistem tracking sebesar 0.1136 Watt.

Large Deployable Reflector (LDR)

Science.gov (United States)

Alff, W. H.

1980-01-01

The feasibility and costs were determined for a 1 m to 30 m diameter ambient temperature, infrared to submillimeter orbiting astronomical telescope which is to be shuttle-deployed, free-flying, and have a 10 year orbital life. Baseline concepts, constraints on delivery and deployment, and the sunshield required are examined. Reflector concepts, the optical configuration, alignment and pointing, and materials are also discussed. Technology studies show that a 10 m to 30 m diameter system which is background and diffraction limited at 30 micron m is feasible within the stated time frame. A 10 m system is feasible with current mirror technology, while a 30 m system requires technology still in development.

Development and validation of a nuclear data and calculation system for Superphenix with steel reflectors

International Nuclear Information System (INIS)

Bosq, J.Ch.

1998-01-01

This thesis concerns the definition and the validation of the ERANOS neutronic calculation system for steel reflected fast reactors. The calculation system uses JEF2.2 evaluated nuclear data, the ECCO cell code and the BISTRO and VARIANT transport codes. After a description of the physical phenomena induced by the existence of the these sub-critical media, an inventory of the past studies related to steel reflectors is reported. A calculational scheme taking into account the important physical phenomena (strong neutronic slowing-down, presence of broad resonances of the structural materials and spatial variation of the spectrum in the reflector) is defined. This method is validated with the TRIPOLI4 reference Monte-Carlo code. The use of this upgraded calculation method for the analysis of the part of the CIRANO experimental program devoted to the study of steel reflected configurations leads to discrepancies between the calculated and measured values. These remaining discrepancies obtained for the reactivity and the fission rate traverses are due to inaccurate nuclear data for the structural materials. The adjustment of these nuclear data in order to reduce these discrepancies id demonstrated. The additional uncertainty associated to the integral parameters of interest for a nuclear reactor (reactivity and power distribution) induced by the replacement of a fertile blanket by a steel reflector is determined for the Superphenix reactor and is proved to be small. (author)

Design of a C- Band Circular Polarization Microstrip Antenna

Science.gov (United States)

Yohandri; Jumiah, Yusna; Tetuko Sri Sumantyo, Josaphat

2018-04-01

The development of circularly polarized microstrip antenna is an interesting topic in current research, due to its superiority in various applications. In this work, the design of a circular polarization antenna that will be operated in the C-band range will be described. The developed antenna is intended to be used for Synthetic Aperture Radar (SAR) applications. Through this application, various targets or areas on the surface of the earth, such as buildings, soil and land can be observed. To get the ideal antenna characteristic, in this research the various parameters in antenna design will be simulated. A software CST Studio will be operated in this simulation. Based on the simulation results, the optimum parameters are obtained in term of reflection coefficient, VSWR, axial ratio, and gain. The reflection coefficient of the antenna (S11) is obtained at -19.75 dB and VSWR of 1.23. Meanwhile, the axial ratio and gain of the antenna were obtained at 2.66 dB and 2.1 dBi, respectively. Based on this simulated results, antenna design is potential to be developed and fabricated for SAR sensor applications.

Beyond Wires and Seeds: Reflector-guided Breast Lesion Localization and Excision.

Science.gov (United States)

Mango, Victoria L; Wynn, Ralph T; Feldman, Sheldon; Friedlander, Lauren; Desperito, Elise; Patel, Sejal N; Gomberawalla, Ameer; Ha, Richard

2017-08-01

Purpose To evaluate outcomes of Savi Scout (Cianna Medical, Aliso Viejo, Calif) reflector-guided localization and excision of breast lesions by analyzing reflector placement, localization, and removal, along with target excision and rates of repeat excision (referred to as re-excision). Materials and Methods A single-institution retrospective review of 100 women who underwent breast lesion localization and excision by using the Savi Scout surgical guidance system from June 2015 to May 2016 was performed. By using image guidance 0-8 days before surgery, 123 nonradioactive, infrared-activated, electromagnetic wave reflectors were percutaneously inserted adjacent to or within 111 breast targets. Twenty patients had two or three reflectors placed for bracketing or for localizing multiple lesions, and when ipsilateral, they were placed as close as 2.6 cm apart. Target and reflector were localized intraoperatively by one of two breast surgeons who used a handpiece that emitted infrared light and electromagnetic waves. Radiographs of the specimen and pathologic analysis helped verify target and reflector removal. Target to reflector distance was measured on the mammogram and radiograph of the specimen, and reflector depth was measured on the mammogram. Pathologic analysis was reviewed. Re-excision rates and complications were recorded. By using statistics software, descriptive statistics were generated with 95% confidence intervals (CIs) calculated. Results By using sonographic (40 of 123; 32.5%; 95% CI: 24.9%, 41.2%) or mammographic (83 of 123; 67.5%; 95% CI: 58.8% 75.1%) guidance, 123 (100%; 95% CI: 96.4%, 100%) reflectors were placed. Mean mammographic target to reflector distance was 0.3 cm. All 123 (100%; 95% CI: 96.4%, 100%) targets and reflectors were excised. Pathologic analysis yielded 54 of 110 malignancies (49.1%; 95% CI: 39.9%, 58.3%; average, 1.0 cm; range, 0.1-5 cm), 32 high-risk lesions (29.1%; 95% CI: 21.4%, 38.2%), and 24 benign lesions (21.8%; 95% CI

Optically Transparent Nano-Patterned Antennas: A Review and Future Directions

Directory of Open Access Journals (Sweden)

Seung Yoon Lee

2018-05-01

Full Text Available Transparent antennas have been continuously developed for integration with solar cells, vehicular communications, and ultra-high-speed communications such as 5G in recent years. A transparent antenna takes advantage of spatial extensibility more so than all other antennas in terms of wide range of usable area. In addition, the production price of transparent antennas is steadily decreasing due to the development of nano-process technology. This paper reviews published studies of transparent antennas classified by various materials in terms of optical transmittance and electrical, sheet resistance. The transparent electrodes for the transparent antenna are logically classified and the transparent antennas are described according to the characteristics of each electrode. Finally, the contributions transparent antennas can make toward next-generation 5G high-speed communication are discussed.

Performance Improvement of Solar Water Stills by Using Reflectors

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Humphrey Hamusonde Maambo

2016-09-01

Full Text Available The lack of safe and clean drinking water sources is one of the problems faced in most rural communities in Zambia. Water in these communities is mostly obtained from shallow wells and rivers. However, this water might be potentially contaminated with harmful substances such as pathogenic bacteria and therefore, unsafe for drinking. Solar water distillation represents an important alternative to palliate problems of fresh water shortages. Solar water stills can be used to eliminate harmful substances from contaminated water by treating it using free solar energy before it can be consumed. Therefore, there is a need to improve solar still performance to produce a greater quantity of safe drinking water. One possible method to improve performance is through adding reflectors to solar stills. Reflectors improve performance by increasing the quantity of distillate by about 22.3 % at a water depth of 15 mm and about 2 9% at a water depth of 10 mm when compared to the distillate produced from a still without reflectors. The water produced using solar stills with reflectors was tested and adhered to World Health Organization (WHO drinking water standards. This implies that solar distillation with reflectors could be adopted at a larger scale to produce safer drinking water at a reduced cost.

Microstrip Antenna Design for Femtocell Coverage Optimization

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Afaz Uddin Ahmed

2014-01-01

Full Text Available A mircostrip antenna is designed for multielement antenna coverage optimization in femtocell network. Interference is the foremost concern for the cellular operator in vast commercial deployments of femtocell. Many techniques in physical, data link and network-layer are analysed and developed to settle down the interference issues. A multielement technique with self-configuration features is analyzed here for coverage optimization of femtocell. It also focuses on the execution of microstrip antenna for multielement configuration. The antenna is designed for LTE Band 7 by using standard FR4 dielectric substrate. The performance of the proposed antenna in the femtocell application is discussed along with results.

Reflectarray antennas theory, designs, and applications

CERN Document Server

Nayeri, Payam; Elsherbeni, Atef Z

2018-01-01

This book provides engineers with a comprehensive review of the state-of-the-art in reflectarray antenna research and development. The authors describe, in detail, design procedures for a wide range of applications, including broadband, multi-band, multi-beam, contour-beam, beam-scanning, and conformal reflectarray antennas. They provide sufficient coverage of basic reflectarray theory to fully understand reflectarray antenna design and analysis such that the readers can pursue reflectarray research on their own. Throughout the book numerous illustrative design examples including numerical and experimental results are provided. Featuring in-depth theoretical analysis along with practical design examples, Reflectarray Antennas is an excellent text/reference for engineering graduate students, researchers, and engineers in the field of antennas. It belongs on the bookshelves of university libraries, research institutes, and industrial labs and research facilities.

SAFARI-1 research reactor beryllium reflector element replacement, management and relocation

International Nuclear Information System (INIS)

Kock, Marisa De; Vlok, Jwh; Steynberg, B.J.

2012-01-01

The beryllium (Be) reflector elements of the SAFARI-1 Research Reactor were replaced in October 2011 as part of the Ageing Management Programme of the reactor. After more than three million MWh of operation over a period of 47 years, core reloading became more difficult due to the geometric deformation of the beryllium reflector elements. During the replacement of the reflector elements, criticality and reactivity worth experiments were performed and found to compare favorably with calculated values. A Beryllium Management Programme was established at SAFARI-1 to identify and apply effective and appropriate actions and practices for managing the ageing of the new beryllium reflector elements. This will provide timely detection and mitigation of ageing mechanisms relevant to beryllium reflector elements, supporting the life extension of these elements. These actions and practices include monitoring of the tritium levels in the primary water, calculating and measuring the fluxes within the beryllium reflector positions, measuring the straightness of the elements to track geometric deformation and visually inspecting the reflector elements for crack formation. Acceptance criteria indicating the end of life of the elements were established. These criteria take into account the smallest gap that could exist between elements, sudden changes in the tritium levels and formation of cracks. All the data obtained through the Beryllium Management Programme are recorded in a database. Additional benefits gained through a Beryllium Management Programme are the availability of a complete irradiation history of the beryllium reflector elements at any point in time and the establishment of a knowledge base to assists in the understanding of the behavior of the beryllium reflector elements in an irradiation environment. Straightness baseline measurements of the new beryllium reflector elements were performed with a beryllium straightness measurement tool, designed at SAFARI-1. The

SAFARI-1 research reactor beryllium reflector element replacement, management and relocation

Energy Technology Data Exchange (ETDEWEB)

Kock, Marisa De; Vlok, Jwh; Steynberg, B J [South Africa Atomic Energy Corporation (Necsa) (South Africa)

2012-03-15

The beryllium (Be) reflector elements of the SAFARI-1 Research Reactor were replaced in October 2011 as part of the Ageing Management Programme of the reactor. After more than three million MWh of operation over a period of 47 years, core reloading became more difficult due to the geometric deformation of the beryllium reflector elements. During the replacement of the reflector elements, criticality and reactivity worth experiments were performed and found to compare favorably with calculated values. A Beryllium Management Programme was established at SAFARI-1 to identify and apply effective and appropriate actions and practices for managing the ageing of the new beryllium reflector elements. This will provide timely detection and mitigation of ageing mechanisms relevant to beryllium reflector elements, supporting the life extension of these elements. These actions and practices include monitoring of the tritium levels in the primary water, calculating and measuring the fluxes within the beryllium reflector positions, measuring the straightness of the elements to track geometric deformation and visually inspecting the reflector elements for crack formation. Acceptance criteria indicating the end of life of the elements were established. These criteria take into account the smallest gap that could exist between elements, sudden changes in the tritium levels and formation of cracks. All the data obtained through the Beryllium Management Programme are recorded in a database. Additional benefits gained through a Beryllium Management Programme are the availability of a complete irradiation history of the beryllium reflector elements at any point in time and the establishment of a knowledge base to assists in the understanding of the behavior of the beryllium reflector elements in an irradiation environment. Straightness baseline measurements of the new beryllium reflector elements were performed with a beryllium straightness measurement tool, designed at SAFARI-1. The

Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

Energy Technology Data Exchange (ETDEWEB)

Stenzel, R. L., E-mail: stenzel@physics.ucla.edu; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

2015-07-15

Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B{sub 0}. Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B{sub 0}. The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B{sub 0} has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental

Magnetic antenna excitation of whistler modes. IV. Receiving antennas and reciprocity

International Nuclear Information System (INIS)

Stenzel, R. L.; Urrutia, J. M.

2015-01-01

Antenna radiation patterns are an important property of antennas. Reciprocity holds in free space and the radiation patterns for exciting and receiving antennas are the same. In anisotropic plasmas, radiation patterns are complicated by the fact that group and phase velocities differ and certain wave properties like helicity depend on the direction of wave propagation with respect to the background magnetic field B 0 . Interference and wave focusing effects are different than in free space. Reciprocity does not necessarily hold in a magnetized plasma. The present work considers the properties of various magnetic antennas used for receiving whistler modes. It is based on experimental data from exciting low frequency whistler modes in a large uniform laboratory plasma. By superposition of linear waves from different antennas, the radiation patterns of antenna arrays are derived. Plane waves are generated and used to determine receiving radiation patterns of different receiving antennas. Antenna arrays have radiation patterns with narrow lobes, whose angular position can be varied by physical rotation or electronic phase shifting. Reciprocity applies to broadside antenna arrays but not to end fire arrays which can have asymmetric lobes with respect to B 0 . The effect of a relative motion between an antenna and the plasma has been modeled by the propagation of a short wave packet moving along a linear antenna array. An antenna moving across B 0 has a radiation pattern characterized by an oscillatory “whistler wing.” A receiving antenna in motion can detect any plane wave within the group velocity resonance cone. The radiation pattern also depends on loop size relative to the wavelength. Motional effects prevent reciprocity. The concept of the radiation pattern loses its significance for wave packets since the received signal does not only depend on the antenna but also on the properties of the wave packet. The present results are of fundamental interest and of

Antennas in inhomogeneous media

CERN Document Server

Galejs, Janis; Fock, V A; Wait, J R

2013-01-01

Antennas in Inhomogeneous Media details the methods of analyzing antennas in such inhomogeneous media. The title covers the complex geometrical configurations along with its variational formulations. The coverage of the text includes various conditions the antennas are subjected to, such as antennas in the interface between two media; antennas in compressible isotropic plasma; and linear antennas in a magnetoionic medium. The selection also covers insulated loops in lossy media; slot antennas with a stratified dielectric or isotropic plasma layers; and cavity-backed slot antennas. The book wil

Slovakia: Proposal of movable reflector for fast reactor design

International Nuclear Information System (INIS)

Vrban, B.

2015-01-01

In fast reactors a larger migration area leading to a significant leak of neutrons can be observed because especially the transport cross-sections are in general smaller as compared to light water reactors. The utilization of a moveable reflector system in conjunction with dedicated safety control rods can increase the ability of accident managing due to enhanced escaping neutrons which otherwise would be reflected back into the fuel zone. The paper demonstrates the possibility of better controlling the transient reactor by additionally moving selected reflector subassemblies equipped with the neutron trap. The main purpose of the analysis of the Gas-cooled Fast Reactor (GFR) presented in the full paper is investigation of the kinetic parameters and of the control and reflector rod worth, as well as optimization of the parts used for partial reflector withdrawal. The results found in this study may serve for future design improvements of other designs such as the liquid metal cooled fast reactors

Sensitivity analysis of reflector types and impurities in a 10 MW MTR type nuclear research reactor

International Nuclear Information System (INIS)

Khattab, K.; Khamis, I.

2008-01-01

The 2-D and 3-D neutronics models for 10 MW nuclear research reactor of MTR type have been developed and presented in this paper. Our results agree very well with the results of seven countries mentioned in the IAEA-TECDOC-233. To study the effect of reflector types on the reactor effective multiplication factor, five types of reflectors such as pure beryllium, beryllium, heavy water, carbon and water are selected for this study. The pure beryllium is found to be the most efficient reflector in this group. The effect of the most important impurities, which exist on the beryllium reflector such as iron, silicon and aluminium on the reactor multiplication factor, have been analyzed as well. It is found that the iron impurity affects the reactor multiplication factor the most compared to silicon and aluminium impurities. (author)

Enhanced light absorption of silicon solar cells with dielectric nanostructured back reflector

Science.gov (United States)

Ren, Rui; Zhong, Zheng

2018-06-01

This paper investigates the light absorption property of nanostructured dielectric reflectors in silicon thin film solar cells using numerical simulation. Flat thin film solar cell with ZnO nanostructured back reflector can produce comparable photocurrent to the control model with Ag nanostructured back reflector. Furthermore, when it is integrated with nano-pillar surface decoration, a photocurrent density of 29.5 mA/cm2 can be achieved, demonstrating a photocurrent enhancement of 5% as compared to the model with Ag nanostructured back reflector.

Extended exploding reflector concept for computing prestack traveltimes for waves of different type in the DSR framework

KAUST Repository

Duchkov, Anton A.; Serdyukov, Alexander S.; Alkhalifah, Tariq Ali

2013-01-01

including reflected, head and diving waves. We develop a WENO-RK numerical scheme for solving all mentioned forms of the DSR equation. Finally the extended exploding reflector concept can be used for computing prestack traveltimes while initiating the numerical solver as if a reflector was exploding in extended imaging space.

Development and test of decoupler for ICRF antenna in EAST

Energy Technology Data Exchange (ETDEWEB)

Chen, Gen, E-mail: chengen@ipp.ac.cn; Mao, Yuzhou; Zhao, Yanping; Yuan, Shuai; Zhang, Xinjun; Qing, Chengming

2016-06-15

Highlights: • The mechanism of decoupler for ICRF antenna is proposed. • Three candidate assembly positions for the decouper can be used. • The performance relies on the ohmic dissipation and the assembly position of decoupler. - Abstract: Ion Cyclotron Range of Frequency (ICRF) heating has been adopted in EAST tokamak as one of main auxiliary heating methods. The ICRF antenna usually consists of multiple launching elements because of limited port and space of tokamak device. Mutual coupling between straps has been observed in previous EAST ICRF current drive experiments. Due to adverse effects of such mutual coupling, many issues induced by cross power cannot be ignored, such as power imbalance in feed lines, high voltage standing wave ratio (VSWR), and etc. To restrain such mutual coupling, A device named decoupler was developed and tested in EAST ICRF system. According to the admittance matrix of load, three assembly positions (oscillation position, optimum position, and smooth position) along transmission line for the decoupler were taken into account and tested. The test results showed that ohmic dissipation in decoupler could not be neglected, which partly influenced the decoupling performance. The oscillation position and optimum position could restrain such adverse effects of ohmic dissipation and showed good decoupling performance. However, they cannot ensure the steady operation during H-mod due to the load variation. Finally, the smooth position has been adopted for EAST I port antenna because of steady decoupling performance comprised with engineering error and load resilience, which sincerely enhance the capability of system operation.

5G MIMO Conformal Microstrip Antenna Design

Directory of Open Access Journals (Sweden)

Qian Wang

2017-01-01

Full Text Available With the development of wireless communication technology, 5G will develop into a new generation of wireless mobile communication systems. MIMO (multiple-input multiple-output technology is expected to be one of the key technologies in the field of 5G wireless communications. In this paper, 4 pairs of microstrip MIMO conformal antennas of 35 GHz have been designed. Eight-element microstrip Taylor antenna array with series-feeding not only achieves the deviation of the main lobe of the pattern but also increases the bandwidth of the antenna array and reduces sidelobe. MIMO antennas have been fabricated and measured. Measurement results match the simulation results well. The return loss of the antenna at 35 GHz is better than 20 dB, the first sidelobe level is −16 dB, and the angle between the main lobe and the plane of array is 60°.

Development of a linear motion antenna for the JT-60SA ECRF system

International Nuclear Information System (INIS)

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; Wada, Kenji; Sato, Yoshikatsu

2013-01-01

Highlights: ► Development of an antenna featuring linear motion (LM) concept for long pulse electron cyclotron range of frequency (ECRF) heating and current drive in JT-60SA is in progress. ► A mock-up using a metallic sliding bearing with solid lubricant was fabricated. ► A vacuum pumping test with mass analyzer showed evidence of some hydrocarbons during shaft motion. ► Injection beam profile in toroidal beam scan was checked by low power measurement with mock-up. ► Current drive characteristics with the LM antenna for typical experimental scenarios of JT-60SA have been investigated by calculation. -- Abstract: Development of an antenna that features the linear motion (LM) concept for long-pulse electron-cyclotron range of frequency heating and current drive for the JT-60SA is in progress. Combining a linearly movable first mirror and a fixed curved second mirror allows the injection-beam angle to be controlled. Cooling water is fed through the drive shaft for the first mirror and through the fixed support for the second mirror. The shaft support structure uses a metallic sliding bearing with a solid lubricant. The sliding bearing supports combined linear and rotational motion, whereas a conventional ball bearing supports either linear or rotational motion. Therefore, the sliding bearing offers the advantage of reducing the support-structure volume, which is important in the design of the relatively narrow port duct of the JT-60SA. Recently, the sliding bearing has been installed into the mockup. Results of a vacuum test with a mass analyzer indicate the presence of hydrocarbons during shaft motion. The injection-beam profile obtained from a toroidal beam scan is checked against low-power measurements taken on the mockup. Finally, for typical JT-60SA experimental scenarios, heating- and current-drive characteristics of the LM antenna are investigated theoretically

Present and future JET ICRF antennae

International Nuclear Information System (INIS)

Kaye, A.; Brown, T.; Bhatnagar, V.; Crawley, P.; Jacquinot, J.; Lobel, R.; Plancoulaine, J.; Rebut, P.H.; Wade, T.; Walker, C.

1994-01-01

Since the initial operation of the JET ICRF system in 1985, up to 22 MW has been coupled to the plasma, many heating scenarios have been demonstrated and the main technological problem of RF-specific impurity production overcome. Many developments of the antennae have taken place over this period, notably the replacement of the water-cooled nickel screens with indirectly cooled beryllium screens, and the forthcoming installation of eight new A2 antennae for operation during the pumped divertor phase of JET. The A2 antennae include enhanced provision for fast wave current drive experiments on JET. This paper describes the beryllium screens, the technological results from operation and subsequent inspection of these screens, the design of the A2 antennae and the results from high power RF testing of a model of the A2 antenna. (orig.)

Performance Verification on UWB Antennas for Breast Cancer Detection

Directory of Open Access Journals (Sweden)

Vijayasarveswari V.

2017-01-01

Full Text Available Breast cancer is a common disease among women and death figure is continuing to increase. Early breast cancer detection is very important. Ultra wide-band (UWB is the promising candidate for short communication applications. This paper presents the performance of different types of UWB antennas for breast cancer detection. Two types of antennas are used i.e: UWB pyramidal antenna and UWB horn antenna. These antennas are used to transmit and receive the UWB signal. The collected signals are fed into developed neural network module to measure the performance efficiency of each antenna. The average detection efficiency is 88.46% and 87.55% for UWB pyramidal antenna and UWB horn antenna respectively. These antennas can be used to detect breast cancer in the early stage and save precious lives.

An Overview of Antenna R&D Efforts in Support of NASA's Space Exploration Vision

Science.gov (United States)

Manning, Robert M.

2007-01-01

This presentation reviews the research and development work being conducted at Glenn Research Center in the area of antennas for space exploration. In particular, after reviewing the related goals of the agency, antenna technology development at GRC is discussed. The antennas to be presented are large aperture inflatable antennas, phased array antennas, a 256 element Ka-band antenna, a ferroelectric reflectarray antenna, multibeam antennas, and several small antennas.

Development of a Semielliptical Partial Ground Plane Antenna for RFID and GSM-900

Directory of Open Access Journals (Sweden)

M. R. Zaman

2014-01-01

Full Text Available A novel compact broadband patch antenna for UHF (ultrahigh frequency, RFID (radio frequency identification, and GSM-900 (global system for mobile communications band is shown in this paper. The antenna is composed of an ellipse shape annular ring at the patch. The ground plane of the planar antenna is modified with a semiellipse shape slot. The structure can generate substantial amount of current at the feed-line. The geometry of the antenna is evaluated by using HFSS simulation software and deliberated across the paper. Parametric study is exhibited to delineate the response change of the antenna. The antenna has a physical width of 0.24 λ and length of 0.3 λ. It covers a frequency starting from 0.9 GHz to 1.08 GHz. A fractional bandwidth of 18.2% has been achieved from 0.9 GHz till 1.08 GHz. An average gain of 5.5 dBi is achieved at the resonance frequency. The simulated and measured results have good agreement.

International Mapping of Antenna-Measurement Facilities

DEFF Research Database (Denmark)

Boccia, Luigi; Breinbjerg, Olav; Di Massa, Giuseppe

2006-01-01

This paper presents a comprehensive international mapping of antenna-measurement facilities. This initiative, conducted within the framework of the Antenna Centre of Excellence (ACE) of the European Union, is oriented toward all institutions having research, development, or operational activities...... measurements, in particular from the wireless communication industry, to identify and contact antenna-measurement facilities. The first phase of the mapping showed a significant and encouraging reaction to this initiative, with more than 50 European facilities currently registered. The next phase aims...

Photonic integration and components development for a Ku-band phased array antenna system

NARCIS (Netherlands)

Marpaung, D.A.I.; Zhuang, L.; Burla, M.; Roeloffzen, C.G.H.; Noharet, Bertrand; Wang, Qin; Beeker, W.P.; Beeker, Willem; Leinse, Arne; Heideman, Rene

2011-01-01

In this paper the development of a phased array antenna system using a photonic beamformer is reported. The paper emphasizes on the photonic integration between two main components of the beamformer, namely the photonic beamformer chip and the electroabsorption modulator array. System level

Diagnostics of the SMOS radiometer antenna system at the DTU-ESA spherical near-field antenna test facility

DEFF Research Database (Denmark)

Cappellin, Cecilia; Frandsen, A.; Pivnenko, Sergey

2007-01-01

The recently developed Spherical Wave Expansion-to-Plane Wave Expansion (SWE-to-PWE) antenna diagnostics technique is employed in an investigation of the antenna system in the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) for ESA’s Soil Moisture and Ocean Salinity (SMOS) mission...

Antenna toolkit

CERN Document Server

Carr, Joseph

2006-01-01

Joe Carr has provided radio amateurs and short-wave listeners with the definitive design guide for sending and receiving radio signals with Antenna Toolkit 2nd edition.Together with the powerful suite of CD software, the reader will have a complete solution for constructing or using an antenna - bar the actual hardware! The software provides a simple Windows-based aid to carrying out the design calculations at the heart of successful antenna design. All the user needs to do is select the antenna type and set the frequency - a much more fun and less error prone method than using a con

Low-cost Antenna Positioning System Designed with Axiomatic Design

Directory of Open Access Journals (Sweden)

Timothy Foley Joseph

2017-01-01

Full Text Available The Engineering Optimization and Modeling Center at Reykjavik University has been carrying out research on antenna CAD, including the simulation-driven design of novel antenna topologies. However, simulation is not enough to validate a design: a custom RF anechoic chamber has been built to quantify antenna performance, particularly in terms of field properties such as radiation patterns. Such experiments require careful positioning of the antenna in the chamber accurately in 3-axis with a short development time, challenging material constraints, and minimal funding. Axiomatic Design Theory principles were applied to develop an automated 3-axis positioner system for a reference antenna and the antenna to be calibrated. Each axis can be individually controlled with a repeatability of 1 degree. This 3000 USD device can be fabricated using easily available components and rapid prototyping tools.

Development and Qualification of an Antenna Pointing Mechanism for the ExoMars High-Gain Antenna

Science.gov (United States)

St-Andre, Stephane; Dumais, Marie-Christine; Lebel, Louis-Philippe; Langevin, Jean-Paul; Horth, Richard; Winton, Alistair; Lebleu, Denis

2015-09-01

The European Space Agency ExoMars 2016 mission required a gimbaled High Gain Antenna (HGA) for orbiter-to-earth communications. The ExoMars Program is a cooperative program between ESA and ROSCOSMOS with participation of NASA. The ExoMars Program industrial consortium is led by THALES ALENIA SPACE.This paper presents the design and qualification test results of the Antenna Pointing Mechanism (APM) used to point the HGA towards Earth. This electrically redundant APM includes motors, drive trains, optical encoders, cable cassette and RF Rotary Joints.Furthermore, the paper describes the design, development and the qualification approach applied to this APM. The design challenges include a wide pointing domain necessary to maximise the communication duty cycle during the early operation phase, the interplanetary cruise phase and during the mission’s orbital science phase. Other design drivers are an extended rotation cycle life with very low backlash yielding little wear and accurate position feedback on both axes. Major challenges and related areas of development include:• Large moments are induced on the APM due to aerobraking forces when the Mars atmosphere is used to slow the orbiter into its science mission orbit,• Thermal control of the critical components of the APM due to the different environments of the various phases of the mission. Also, the large travel range of the actuators complicated the radiator design in order to maintain clearances and to avoid overheating.• The APM, with a mass less than 17.5 kg, is exposed to a demanding dynamic environment due to its mounting on the spacecraft thrust tube and aggravated by its elevated location on the payload.• Power and Data transmission between elevation and azimuth axes through a compact large rotation range spiral type cable cassette.• Integration of a 16 bit redundant encoder on both axes for position feedback: Each encoder is installed on the back of a rotary actuator and is coupled using the

Conformal Lightweight Antenna Structures for Aeronautical Communication Technologies

Science.gov (United States)

Meador, Mary Ann

2017-01-01

This project is to develop antennas which enable beyond line of sight (BLOS) command and control for UAVs. We will take advantage of newly assigned provisional Ku-band spectrum for UAVs and use unique antenna designs to avoid interference with ground systems. This will involve designing antennas with high isotropic effective radiated power (EIRP) and ultra-low sidelobes. The antennas will be made with polymer aerogel as a substrate to both reduce weight and improve performance, as demonstrated in an Aero Seedling. In addition, designing the antennas to be conformal to the aircraft fuselage will reduce drag.

Ellipsoidal reflector for measuring oto-acoustic emissions

DEFF Research Database (Denmark)

Epp, Bastian; Pulkki, Ville; Heiskanen, Vesa

2014-01-01

A truncated prolate ellipsoidal reflector having the ear canal of a listener at one focal point and large- diaphragm low-noise microphone at the other focal point is proposed for free-field recordings of oto-acoustic emissions. A prototype reflector consisting of three pieces is presented, which...... enables measuring the response of the system with different truncations. The response of the system is measured with a miniature loud- speaker, and proof-of-concept measurements of oto-acoustic emissions are presented. The effect of truncation and other physical parameters to the performance of the system...

Near vertical incidence skywave propagation: Elevation angles and optimum antenna height for horizontal dipole antennas

NARCIS (Netherlands)

Witvliet, Ben A.; van Maanen, Erik; Petersen, George J.; Westenberg, Albert J.; Bentum, Marinus Jan; Slump, Cornelis H.; Schiphorst, Roelof

2015-01-01

Near Vertical Incidence Skywave (NVIS) communication uses the ionosphere as a reflector to cover a continuous area with a radius of at least 150 km around the transmitter, on frequencies typically between 3 and 10 MHz. In developing countries, in areas lacking any other telecommunication

Distribution of analytes over TXRF reflectors

International Nuclear Information System (INIS)

Bernasconi, G.; Tajani, A.

2000-01-01

One of the most frequently used methods for trace element analysis in TXRF involves the evaporation of small amounts of aqueous solutions over flat reflectors. This method has the advantage of in-situ pre-concentration of the analytes, which together with the low background due to the total reflection in the substrate leads to excellent detection limits and high signal to noise ratio. The spiking of the liquid sample with an internal standard provides also a simple way to achieve multielemental quantitative analysis. However the elements are not homogeneously distributed over the reflector after the liquid phase has been evaporated. This distribution may be different for the unknown elements and the internal standards and may influence the accuracy of the quantitative results. In this presentation we used μ-XRF techniques to map this distribution. Small (20 μl) drops of a binary solution were evaporated over silicon reflectors and then mapped using a focused X-ray beam with about 100 μm resolution. A typical ring structure showing some differences in the distribution of both elements has been observed. One of the reflectors was also measured in a TXRF setup turning it at different angles with reference to the X-ray beam (with constant incidence and take-off angles) and variations of the intensity relation between both elements were measured. This work shows the influence of the sample distribution and proposes methods to evaluate it. In order to assess the limitations of the accuracy of the results due to the sample distribution more measurements would be necessary, however due to the small size of typical TXRF samples and the tight geometry of TXRF setups the influence of the sample distribution is not large. (author)

Characterization of a Bifacial Photovoltaic Panel Integrated with External Diffuse and Semimirror Type Reflectors

Directory of Open Access Journals (Sweden)

P. Ooshaksaraei

2013-01-01

Full Text Available Silicon wafer accounts for almost one-half the cost of a photovoltaic (PV panel. A bifacial silicon solar cell is attractive due to its potential of enhancing power generation from the same silicon wafer in comparison with a conventional monofacial solar cell. The bifacial PV cell is able to capture solar radiation by back surface. This ability requires a suitable reflector appropriately oriented and separated from the cell’s rear surface. In order to optimize the bifacial solar cell performance with respect to an external back surface reflector, diffuse and semimirror reflectors were investigated at various angles and separations from the back surface. A simple bifacial solar panel, consisting of four monocrystalline Si solar cells, was designed and built. Reflection from the rear surface was provided by an extended semimirror and a white-painted diffuse reflector. Maximum power generation was observed at 30° with respect to ground for the semimirror reflector and 10° for diffuse reflector at an optimized reflector-panel separation of 115 mm. Output power enhancement of 20% and 15% from semimirror and diffuse reflectors, respectively, were observed. This loss from diffuse reflector is attributed to scattering of light beyond the rear surface capture cross-section of the bifacial solar panel.

Antenna conditioning with insulating antenna tiles in Phaedrus-T

International Nuclear Information System (INIS)

Intrator, T.; Probert, P.; Doczy, M.; Diebold, D.; Brouchous, D.

1994-01-01

In the course of our Alfven wave heating and current drive experiments several different two and four strap antennas have been installed in Phaedrus-T. The motivation focusing the redesign of the antenna into a four strap design was to enable traveling wave phasing, and to reduce the k parallel ∼0 component of the wavenumber spectrum, and consequent edge power deposition. The latest modifications to the 4 strap antenna have dramatically improved its behavior, and enabled us to suppress its RF power induced impurity generation. The remaining gas reflux fueling is significant and is not local to the antenna

Theoretical methods for neutronics calculations of core-blanket and core-reflector systems in fast reactors

International Nuclear Information System (INIS)

Corcuera, Roberto.

1975-12-01

The present work is a contribution to the neutronics calculational methods of fast neutron reactors. The first step is devoted to the analysis of the validity of the few-groups (of the order of 25) multigroup scheme, and of the transport-correction approximation for the treatment of the scattering anisotropy. This analysis includes both the reactor core, where the usual approximations are found to be satisfactory, and the reflector, where it turns out that the rapid variations of the neutron flux and of it's spectrum necessitate the improvement of the multigroup cross-sections' generation. Therefore, a zero-dimensional simple and accurate model for the average spectrum in the reflector is developed by the space-energy synthesis method. Finally using the Rayleigh-Ritz method, a model is developed in which the flux is spatially represented by an analytical function. This model is applied to the analysis of the sensitivity of reflector neutronics parameters to the variations of the cross sections [fr

Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

International Nuclear Information System (INIS)

Lee, Hyun Jin; Kim, Jong Kyu; Lee, Sang Nam

2015-01-01

In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m 2 . When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system

Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyun Jin [Kookmin Univ., Seoul (Korea, Republic of); Kim, Jong Kyu; Lee, Sang Nam [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2015-12-15

In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m{sup 2}. When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system.

Affordable Unfurlable Fan-Fold Wrapable Reflector for Small and Large Apertures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Deployable Space Systems (DSS) will focus the proposed SBIR program on the development and concept feasibility of an innovative deployable mesh/membrane reflector...

The analysis of radiation parameters dependence of rectangular waveguide on its dimensions change

Directory of Open Access Journals (Sweden)

Manoilov V.P.

2016-04-01

Full Text Available Analysis of radiation from 3 centimeter waveband rectangular waveguide at the change of the side sizes is carried out for the purpose of efficiency estimation of its use as reflector parabolic antenna exciter. Some performance characteristics of radioelectronic systems depend on antennas types which are used. Recently, the development of antenna systems occurred mainly not by creating new, and by improving the parameters and characteristics of existing antennas. Therefore, there is a practical need to find ways to improve their elements. A detailed analysis of the radiation from the open end of the rectangular waveguide allows to specify exactly which of its parameters and characteristics need to be improved. Dependence charts of directional diagram (DD in planes E and H, radiation power, directivity upon variation of side sizes a, b are received. Dependence charts of attenuation coefficient upon frequency for wave types H10, H01, H02, H11, E11 are drawn up. Estimation of reasonability of using rectangular waveguide as reflector parabolic antenna exciter is received.

Development of a new lower hybrid antenna module using a poloidal power divider

International Nuclear Information System (INIS)

Maebara, Sunao; Seki, Masami; Suganuma, Kazuaki

1996-07-01

The antenna using poloidal power divider is an effective method for simplification of Lower Hybrid Current Drive (LHCD) antenna system. This method should allow to reduce the power density in the antenna while maintaining a good flexibility of N parallel spectrum of waves. For this purpose, three types of poloidal power divider which split the power in three, and the 3 x 6 multi-junction module were developed. r.f. properties and outgassing of these components were evaluated using the CEA Cadarache RF Test Facility. A good power dividing ratio of 33 ± 4% was obtained for each of these poloidal dividers, and the reflection coefficient was lower value than 1.5%. For the 3 x 6 multi-junction, reflection coefficient was less than 1.3% and r.f. losses lower than 1.0% were measured. On the other hand, it was found in the scattering matrix analysis that reflection coefficient at plasma has to be less than a few % in order to operate these components under available conditions. In combination with two poloidal power dividers connected to the 3 x 6 multi-junction module, quasi stationary operation for r.f. injection time of 1000 sec at 300 kW was demonstrated under water cooling. In this case, it was found that the outgassing rate is in the lower range of 10 -7 Pam 3 s -1 m -2 within the maximum module temperature of ∼100degC. This report describes the experimental and analytical results of a new lower hybrid (LH) antenna module using the poloidal power divider. (author)

Active patch antennas for transponder applications

Energy Technology Data Exchange (ETDEWEB)

Biffi Gentili, G; Avitabile, G; Bonifacio, F; Salvador, C [Florence Univ. (Italy). Dip. di Ingegneria Elettronica

1996-01-01

The paper deals with two patch antenna structures that are mainly taught for short range link and non-contact identification system (RFID). The proposed antennas were developed by starting from an original concept of cross-polarization usefully applicable, in compliance with european for transponder applications are described and experimental results are reported.

Antenna Controller Replacement Software

Science.gov (United States)

Chao, Roger Y.; Morgan, Scott C.; Strain, Martha M.; Rockwell, Stephen T.; Shimizu, Kenneth J.; Tehrani, Barzia J.; Kwok, Jaclyn H.; Tuazon-Wong, Michelle; Valtier, Henry; Nalbandi, Reza;

Measurement of the stored energy in the NRX reactor reflector graphite

Energy Technology Data Exchange (ETDEWEB)

Hilton, H. B.; Larson, E. A.G.

1959-07-15

With the co-operation of workers at Windscale and Harwell, whose assistance is hereby gratefully acknowledged, the stored energy content of the inner reflector graphite of NRX has been measured. Measurements made at three different elevations and at different positions through the reflector show that there is, at present, no danger to NRX from an accidental release of the energy. The energy stored in the reflector in 1958 is less by a factor five to ten than the stored energy as measured in 1953. It appears that there has been a continual release of stored energy since 1954 when, after the rehabilitation, the maximum power was raised to 40 MW. Additional thermocouples have been installed in the inner reflector, and future stored energy measurements are being scheduled. (author)

Efficiency improvement of flat plate solar collector using reflector

Directory of Open Access Journals (Sweden)

Himangshu Bhowmik

2017-11-01

Full Text Available Solar collectors are the main components of a solar heating system. The collectors collect the sun’s energy, transform this radiation into heat, and then transfer this heat into a fluid, water or air, which has many household or industrial applications. This paper introduces a new technology to improve the performance of the solar thermal collectors. The solar reflector used here with the solar collector to increase the reflectivity of the collector. Thus, the reflector concentrates both direct and diffuse radiation of the sun toward the collector. To maximize the intensity of incident radiation, the reflector was allowed to change its angle with daytime. The radiations coming from the sun’s energy were converted into heat, and then this heat was transferred to the collector fluid, water. A prototype of a solar water heating system was constructed and obtained the improvement of the collector efficiency around 10% by using the reflector. Thus, the present solar water heating systems having the best thermal performance compared to the available systems.

Variation of reflected radiation from all reflectors of a flat plate solar collector during a year

International Nuclear Information System (INIS)

Pavlović, Zoran T.; Kostić, Ljiljana T.

2015-01-01

In this paper the impact of flat plate reflectors (bottom, top, left and right reflectors) made of Al, on total solar radiation on a solar collector during a day time over a whole year is analyzed. An analytical model for determining optimum tilt angles of a collector and reflectors for any point on the Earth is proposed. Variations of reflectors' optimal inclination angles with changes of the collector's optimal tilt angle during the year are also calculated. Optimal inclination angles of the reflectors for the South directed solar collector are calculated and compared to experimental data. It is shown that optimal inclination of the bottom reflector is the lowest in December and the highest in June, while for the top reflector the lowest value is in June and the highest value is in December. On the other hand, optimal inclination of the left and right side reflectors for optimum tilt angle of the collector does not change during the year and it is 66°. It is found that intensity of the solar radiation on the collector increases for about 80% in the summer period (June–September) by using optimally inclined reflectors, in comparison to the collector without reflectors. - Highlights: • The impacts of flat plate reflectors on solar radiation on the collector are given. • The results of the optimal inclinations of reflectors during the year are shown. • The solar radiation on the collector with reflectors is 80% higher in the summer. • This model may be applied on thermal, PV, PV/T and energy harvesting systems

Antenna Miniaturization in Complex Electromagnetic Environments

DEFF Research Database (Denmark)

Zhang, Jiaying

improved compared to the 2-D planar electrically small loop antennas. Measurement Techniques for ESAs In this dissertation we proposed two novel measurement techniques for electrically small antennas. A modified Wheeler cap method for the radiation efficiency measurement of balanced electrically small....... Moreover, the modified Wheeler cap method for measurements of small antennas in complex environments is further developed. A cable-free impedance and gain measurement technique for electrically small antennas is also proposed. The electromagnetic model of this technique is derived by using the spherical...... wave expansion, and it is valid for arbitrary electrically small AUT at arbitrary distances between the probe and AUT. The whole measurement setup is modeled by the cascade of three coupled multipleort networks. The electromagnetic model, the simulation results, and the obtained measurement results...

Development of horn antenna mixer array with internal local oscillator module for microwave imaging diagnostics

Energy Technology Data Exchange (ETDEWEB)

Kuwahara, D., E-mail: dkuwahar@cc.tuat.ac.jp [Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Ito, N. [Department of Intelligent System Engineering, Ube National College of Technology, Ube, Yamaguchi 755-8555 (Japan); Nagayama, Y. [Department of Helical Plasma Research, National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Yoshinaga, T. [Department of Applied Physics, National Defense Academy, Yokosuka, Kanagawa 239-0811 (Japan); Yamaguchi, S. [Department of Pure and Applied Physics, Kansai University, Suita, Osaka 564-8680 (Japan); Yoshikawa, M.; Kohagura, J. [Graduate School of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Sugito, S. [Equipment Development Center, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan); Kogi, Y. [Department of Information Electronics, Fukuoka Institute of Technology, Fukuoka, Fukuoka 811-0295 (Japan); Mase, A. [Art, Science and Technology Center for Cooperative Research, Kyusyu University, Kasuga, Fukuoka 816-8580 (Japan)

2014-11-15

A new antenna array is proposed in order to improve the sensitivity and complexity of microwave imaging diagnostics systems such as a microwave imaging reflectometry, a microwave imaging interferometer, and an electron cyclotron emission imaging. The antenna array consists of five elements: a horn antenna, a waveguide-to-microstrip line transition, a mixer, a local oscillation (LO) module, and an intermediate frequency amplifier. By using an LO module, the LO optics can be removed, and the supplied LO power to each element can be equalized. We report details of the antenna array and characteristics of a prototype antenna array.

Identifying Reflectors in Seismic Images via Statistic and Syntactic Methods

Directory of Open Access Journals (Sweden)

Carlos A. Perez

2010-04-01

Full Text Available In geologic interpretation of seismic reflection data, accurate identification of reflectors is the foremost step to ensure proper subsurface structural definition. Reflector information, along with other data sets, is a key factor to predict the presence of hydrocarbons. In this work, mathematic and pattern recognition theory was adapted to design two statistical and two syntactic algorithms which constitute a tool in semiautomatic reflector identification. The interpretive power of these four schemes was evaluated in terms of prediction accuracy and computational speed. Among these, the semblance method was confirmed to render the greatest accuracy and speed. Syntactic methods offer an interesting alternative due to their inherently structural search method.

Numerical form-finding method for large mesh reflectors with elastic rim trusses

Science.gov (United States)

Yang, Dongwu; Zhang, Yiqun; Li, Peng; Du, Jingli

2018-06-01

Traditional methods for designing a mesh reflector usually treat the rim truss as rigid. Due to large aperture, light weight and high accuracy requirements on spaceborne reflectors, the rim truss deformation is indeed not negligible. In order to design a cable net with asymmetric boundaries for the front and rear nets, a cable-net form-finding method is firstly introduced. Then, the form-finding method is embedded into an iterative approach for designing a mesh reflector considering the elasticity of the supporting rim truss. By iterations on form-findings of the cable-net based on the updated boundary conditions due to the rim truss deformation, a mesh reflector with a fairly uniform tension distribution in its equilibrium state could be finally designed. Applications on offset mesh reflectors with both circular and elliptical rim trusses are illustrated. The numerical results show the effectiveness of the proposed approach and that a circular rim truss is more stable than an elliptical rim truss.

Design and Verification of MIMO 2x2 Reference Antennas

DEFF Research Database (Denmark)

Szini, Istvan Janos; Pedersen, Gert Frølund; Estrada, J.

2012-01-01

The development and initial discussion of a reference MIMO 2×2 antenna concept has been presented in [1]. The reference antenna concept has been created to eliminate the uncertainties linked to the unknown antenna performance of the few LTE MIMO 2×2 reference devices or golden standards currently...... available for evaluating radiated data throughput measurement methodologies and test facilities. The proposed concept is based on simple antennas with a well-known Figure of Merit (FoM) and controllable performance. In this paper we present the recent developments on the antenna concept and report...... on the first measured performance at uniform incoming power distribution, figures and correlations between different measurement labs....

Selection of lamp reflector construction and fishing time of lift net

Directory of Open Access Journals (Sweden)

Gondo Puspito

2017-06-01

Full Text Available This study aimed to determine lift net’s lamp reflector construction which is able to give highest weight on catch and determine the best fishing time. Three lamp reflector constructions were made of cylinder shape for one construction and cone shape with opening angle α = 62° and 90° for two others. The dimension (øR × HR for each reflector are 30 × 37 (cm, 40 × 18 (cm and 40 × 39.62 (cm. Each lamp reflector was being operated by 1 lift net for 15 nights. Total fishing operations were twice per night within interval 07.00–12.00 PM and 00.00–05.00 AM. Results of the catch gave 2 schools of fish which were plankton feeders and predators. Plankton feeders included anchovy Stolephorus spp. 477 kg, mackerel (Rastrelliger spp. 1934 kg, and malayan half (Decapterus sp. 15.5 kg. Predators consisted of hairtail (Trichiurus sp. 982 kg, yellowstrip scad (Selaroides spp. 29 kg, and giant trevally (Caranx sp. 26.3 kg. The lift net which operated lamp reflector of α = 90° has the highest catch of 2,307.8 kg, while the lamp reflector of α = 62° has 1895 kg of catch. The one with cylinder shape has 1261 kg of catch.

Measurement of LHCD antenna position in Aditya tokamak

International Nuclear Information System (INIS)

Ambulkar, K K; Sharma, P K; Virani, C G; Parmar, P R; Thakur, A L; Kulkarni, S V

2010-01-01

To drive plasma current non-inductively in ADITYA tokamak, 120 kW pulsed Lower Hybrid Current Drive (LHCD) system at 3.7 GHz has been designed, fabricated and installed on ADITYA tokamak. In this system, the antenna consists of a grill structure, having two rows, each row comprising of four sub-waveguides. The coupling of LHCD power to the plasma strongly depends on the plasma density near the mouth of grill antenna. Thus the grill antenna has to be precisely positioned for efficient coupling. The movement of mechanical bellow, which contracts or expands up to 50mm, governs the movement of antenna. In order to monitor the position of the antenna precisely, the reference position of the antenna with respect to the machine/plasma position has to be accurately determined. Further a mechanical system or an electronic system to measure the relative movement of the antenna with respect to the reference position is also desired. Also due to poor accessibility inside the ADITYA machine, it is impossible to measure physically the reference position of the grill antenna with respect to machine wall, taken as reference position and hence an alternative method has to be adopted to establish these measurements reliably. In this paper we report the design and development of a mechanism, using which the antenna position measurements are made. It also describes a unique method employing which the measurements of the reference position of the antenna with respect to the inner edge of the tokamak wall is carried out, which otherwise was impossible due to poor accessibility and physical constraints. The position of the antenna is monitored using an electronic scale, which is developed and installed on the bellow. Once the reference position is derived, the linear potentiometer, attached to the bellow, measures the linear distance using position transmitter. The accuracy of measurement obtained in our setup is within +/- 0.5 % and the linearity, along with repeatability is excellent.

Structured surface reflector design for oblique incidence beam splitter at 610 GHz.

Science.gov (United States)

Defrance, F; Casaletti, M; Sarrazin, J; Wiedner, M C; Gibson, H; Gay, G; Lefèvre, R; Delorme, Y

2016-09-05

An iterative alternate projection-based algorithm is developed to design structured surface reflectors to operate as beam splitters at GHz and THz frequencies. To validate the method, a surface profile is determined to achieve a reflector at 610 GHz that generates four equal-intensity beams towards desired directions of ±12.6° with respect to the specular reflection axis. A prototype is fabricated and the beam splitter behavior is experimentally demonstrated. Measurements confirm a good agreement (within 1%) with computer simulations using Feko, validating the method. The beam splitter at 610 GHz has a measured efficiency of 78% under oblique incidence illumination that ensures a similar intensity between the four reflected beams (variation of about 1%).

FDTD simulation tools for UWB antenna analysis.

Energy Technology Data Exchange (ETDEWEB)

Brocato, Robert Wesley

2005-02-01

This paper describes the development of a set of software tools useful for analyzing ultra-wideband (UWB) antennas and structures. These tools are used to perform finite difference time domain (FDTD) simulation of a conical antenna with continuous wave (CW) and UWB pulsed excitations. The antenna is analyzed using spherical coordinate-based FDTD equations that are derived from first principles. The simulation results for CW excitation are compared to simulation and measured results from published sources; the results for UWB excitation are new.

FDTD simulation tools for UWB antenna analysis.

Energy Technology Data Exchange (ETDEWEB)

Brocato, Robert Wesley

2004-12-01

This paper describes the development of a set of software tools useful for analyzing ultra-wideband (UWB) antennas and structures. These tools are used to perform finite difference time domain (FDTD) simulation of a conical antenna with continuous wave (CW) and UWB pulsed excitations. The antenna is analyzed using spherical coordinate-based FDTD equations that are derived from first principles. The simulation results for CW excitation are compared to simulation and measured results from published sources; the results for UWB excitation are new.

Simultaneous delivery of electron beam therapy and ultrasound hyperthermia using scanning reflectors: a feasibility study

International Nuclear Information System (INIS)

Moros, Eduardo G.; Straube, William L.; Klein, Eric E.; Yousaf, Muhammed; Myerson, Robert J.

1995-01-01

Purpose: The feasibility of simultaneously delivering external electron beam radiation and superficial hyperthermia using a scanning ultrasound reflector-array system (SURAS) was experimentally investigated and demonstrated. Methods and Materials: A new system uses a scanning reflector to distribute the acoustic energy from a planar ultrasound array over the surface of the target volume. External photon/electron beams can be concurrently delivered with hyperthermia by irradiating through the scanning reflectors. That is, this system enables the acoustic waves and the radiation beams to enter the target volume from the same direction. Reflectors were constructed of air-equivalent materials for maximum acoustic reflection and minimum radiation attenuation. Acoustically, the air reflectors were compared to brass reflectors (assumed ideal) for reflectivity and specular quality using several single transducers ranging in frequency from 0.68 to 4.8 MHz. The relative reflectivity was determined from acoustic power measurements using a force-balance technique. The specular quality was assessed by comparing the acoustic pressure fields reflected by air reflectors with those reflected by brass reflectors. Also, acoustic pressure fields generated by a SURAS prototype for two different arrays (2.24 and 4.5 MHz) were measured to investigate field distribution variations as a function of the distance separating the array and the scanning reflector. All pressure fields were measured with a hydrophone in a degassed water tank. Finally, to determine the effect of the air reflectors on electron dose distributions, these were measured using film in a water-equivalent solid phantom after passage of a 20 MeV electron beam through the SURAS. These measurements were performed with the reflector scanning continuously across the electron beam and at rest within the electron beam. Results: The measurements performed using single ultrasound transducers showed that the air reflectors had

Reflector homogenization

Energy Technology Data Exchange (ETDEWEB)

Sanchez, R.; Ragusa, J.; Santandrea, S. [Commissariat a l' Energie Atomique, Direction de l' Energie Nucleaire, Service d' Etudes de Reacteurs et de Modelisation Avancee, CEA de Saclay, DM2S/SERMA 91 191 Gif-sur-Yvette cedex (France)]. e-mail: richard.sanchez@cea.fr

2004-07-01

The problem of the determination of a homogeneous reflector that preserves a set of prescribed albedo is considered. Duality is used for a direct estimation of the derivatives needed in the iterative calculation of the optimal homogeneous cross sections. The calculation is based on the preservation of collapsed multigroup albedo obtained from detailed reference calculations and depends on the low-order operator used for core calculations. In this work we analyze diffusion and transport as low-order operators and argue that the P{sub 0} transfers are the best choice for the unknown cross sections to be adjusted. Numerical results illustrate the new approach for SP{sub N} core calculations. (Author)

Reflector homogenization

International Nuclear Information System (INIS)

Sanchez, R.; Ragusa, J.; Santandrea, S.

2004-01-01

The problem of the determination of a homogeneous reflector that preserves a set of prescribed albedo is considered. Duality is used for a direct estimation of the derivatives needed in the iterative calculation of the optimal homogeneous cross sections. The calculation is based on the preservation of collapsed multigroup albedo obtained from detailed reference calculations and depends on the low-order operator used for core calculations. In this work we analyze diffusion and transport as low-order operators and argue that the P 0 transfers are the best choice for the unknown cross sections to be adjusted. Numerical results illustrate the new approach for SP N core calculations. (Author)

ORNL compact loop antenna design for TFTR and Tore Supra

International Nuclear Information System (INIS)

Taylor, D.J.; Baity, F.W.; Bryan, W.E.; Hoffman, D.J.; McIlwain, R.L.; Ray, J.M.

1987-01-01

The goal supplemental ion cyclotron resonance heating (ICRH) of fusion plasma is to deliver power at high efficiencies deep within the plasma. The technology for fast-wave ICRH has reached the point of requiring ''proof-of-performance'' demonstration of specific antenna configurations of specific antenna configurations and their mechanical adequacy for operating in a fusion environment. Oak Ridge National Laboratory (ORNL) has developed the compact loop antenna concept based on a resonant double loop (RDL) configuration for use in both Tokamak Fusion Test Reactor (TFTR) and the Tore Supra ICRH programs. A description and a comparison of the technologies developed in the two designs are presented. The electrical circuit and the mechanical philosophy employed are the same for both antennas, but different operating environments result in substantial differences in the design of specific components. The ORNL TFTR antenna is designed to deliver 4 MW over a 2-s pulse, and the ORNL Tore Supra antenna is designed for 4 MW and essentially steady-state conditions. The TFTR design embodies the first operations compact RDL antenna, and the Tore Supra antenna extends the technology to an operational duty cycle consistent with reactor-relevant applications. 7 refs., 5 figs

Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

Energy Technology Data Exchange (ETDEWEB)

Bakry, A. [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia); Abdulrhmann, S. [Jazan University, 114, Department of Physics, Faculty of Sciences (Saudi Arabia); Ahmed, M., E-mail: mostafa.farghal@mu.edu.eg [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia)

2016-06-15

We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.

GPS antenna designs

Science.gov (United States)

Laube, Samuel J. P.

1987-05-01

Application of the current GPS NAVSTAR system to civilian service requires that a right hand, circularly polarized, -160 dBW spread spectrum signal be received from an orbiting satellite, where the antenna environment is also moving. This presents a design challenge when inexpensive antennas are desired. The intent of this survey is to provide information on the antennas mentioned and to construct and test prototypes to determine whether the choice made by the industry, the quadrifilar helix, is the best. The helix antenna is currently the low cost standard for GPS. Prototype versions were constructed using 12 gauge wire and subminiature coaxial hardline. The constructed antennas were tested using a signal generator and a reference turnstile. A spectrum analyzer was used to measure the level of the received signal.

Borehole radar survey at the granite quarry mine, Pocheon, Kyounggi province

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Ho; Cho, Seong Jun; Yi, Myeong Jong; Chung, Seung Hwan; Lee, Hee Il; Shin, In Chul [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1997-12-01

Borehole radar survey in combination with the reflection and tomography methods was conducted at the Donga granite quarry mine of Pocheon area in Kyounggi province. The purpose of radar survey in quarry mine is to delineate the inhomogeneities including fractures and to estimate the freshness of rock. 20 MHz was adopted as the central frequency for the radar reflection and tomography surveys for the longer distance of penetration. The reflection survey using the direction finding antenna was also conducted to get the information on the spatial orientation of reflectors. Besides the various kinds of radar borehole survey, two surface geophysical methods, dipole-dipole resistivity survey and ground penetrating radar, were also applied to delineate the hidden parts of geological structures which was confirmed by geological mapping. The reflection data processing package, RADPRO ver. 2.2, developed continuously through in this study, was used to process the borehole reflection radar data. The new programs to process radar reflection data using directional antenna were devised and used to calculate and image the orientation of reflectors. The major dip angle of fractured zones were determined from the radar reflection images. With the aid of direction finding antenna and the newly developed algorithm to image the orientation of reflectors, it was possible to get the three dimensional attitudes of reflectors. Detailed interpretation results of the surveyed area are included in this report. Through the interpretation of borehole reflection data using dipole and direction finding antenna, we could determine the orientation of the major fractured zone, the boundary of two mining areas. Many of hidden inhomogeneities were found by borehole radar methods. By the image of direction finding antenna, it was confirmed that nearly all of them were located at the outside of the planned mining area or were situated very deeply. Therefore, the surveyed area consists of very fresh and

Design of Miniaturized Dual-Band Microstrip Antenna for WLAN Application

Science.gov (United States)

Yang, Jiachen; Wang, Huanling; Lv, Zhihan; Wang, Huihui

2016-01-01

Wireless local area network (WLAN) is a technology that combines computer network with wireless communication technology. The 2.4 GHz and 5 GHz frequency bands in the Industrial Scientific Medical (ISM) band can be used in the WLAN environment. Because of the development of wireless communication technology and the use of the frequency bands without the need for authorization, the application of WLAN is becoming more and more extensive. As the key part of the WLAN system, the antenna must also be adapted to the development of WLAN communication technology. This paper designs two new dual-frequency microstrip antennas with the use of electromagnetic simulation software—High Frequency Structure Simulator (HFSS). The two antennas adopt ordinary FR4 material as a dielectric substrate, with the advantages of low cost and small size. The first antenna adopts microstrip line feeding, and the antenna radiation patch is composed of a folded T-shaped radiating dipole which reduces the antenna size, and two symmetrical rectangular patches located on both sides of the T-shaped radiating patch. The second antenna is a microstrip patch antenna fed by coaxial line, and the size of the antenna is diminished by opening a stepped groove on the two edges of the patch and a folded slot inside the patch. Simulation experiments prove that the two designed antennas have a higher gain and a favourable transmission characteristic in the working frequency range, which is in accordance with the requirements of WLAN communication. PMID:27355954

Highly Enriched Uranium Metal Cylinders Surrounded by Various Reflector Materials

International Nuclear Information System (INIS)

Bernard Jones; J. Blair Briggs; Leland Monteirth

2007-01-01

A series of experiments was performed at Los Alamos Scientific Laboratory in 1958 to determine critical masses of cylinders of Oralloy (Oy) reflected by a number of materials. The experiments were all performed on the Comet Universal Critical Assembly Machine, and consisted of discs of highly enriched uranium (93.3 wt.% 235U) reflected by half-inch and one-inch-thick cylindrical shells of various reflector materials. The experiments were performed by members of Group N-2, particularly K. W. Gallup, G. E. Hansen, H. C. Paxton, and R. H. White. This experiment was intended to ascertain critical masses for criticality safety purposes, as well as to compare neutron transport cross sections to those obtained from danger coefficient measurements with the Topsy Oralloy-Tuballoy reflected and Godiva unreflected critical assemblies. The reflector materials examined in this series of experiments are as follows: magnesium, titanium, aluminum, graphite, mild steel, nickel, copper, cobalt, molybdenum, natural uranium, tungsten, beryllium, aluminum oxide, molybdenum carbide, and polythene (polyethylene). Also included are two special configurations of composite beryllium and iron reflectors. Analyses were performed in which uncertainty associated with six different parameters was evaluated; namely, extrapolation to the uranium critical mass, uranium density, 235U enrichment, reflector density, reflector thickness, and reflector impurities. In addition to the idealizations made by the experimenters (removal of the platen and diaphragm), two simplifications were also made to the benchmark models that resulted in a small bias and additional uncertainty. First of all, since impurities in core and reflector materials are only estimated, they are not included in the benchmark models. Secondly, the room, support structure, and other possible surrounding equipment were not included in the model. Bias values that result from these two simplifications were determined and associated

Cryo-optical testing of large aspheric reflectors operating in the sub mm range

Science.gov (United States)

Roose, S.; Houbrechts, Y.; Mazzoli, A.; Ninane, N.; Stockman, Y.; Daddato, R.; Kirschner, V.; Venacio, L.; de Chambure, D.

2006-02-01

The cryo-optical testing of the PLANCK primary reflector (elliptical off-axis CFRP reflector of 1550 mm x 1890 mm) is one of the major issue in the payload development program. It is requested to measure the changes of the Surface Figure Error (SFE) with respect to the best ellipsoid, between 293 K and 50 K, with a 1 μm RMS accuracy. To achieve this, Infra Red interferometry has been used and a dedicated thermo mechanical set-up has been constructed. This paper summarises the test activities, the test methods and results on the PLANCK Primary Reflector - Flight Model (PRFM) achieved in FOCAL 6.5 at Centre Spatial de Liege (CSL). Here, the Wave Front Error (WFE) will be considered, the SFE can be derived from the WFE measurement. After a brief introduction, the first part deals with the general test description. The thermo-elastic deformations will be addressed: the surface deformation in the medium frequency range (spatial wavelength down to 60 mm) and core-cell dimpling.

Development of a new lower hybrid antenna module using a poloidal power divider

International Nuclear Information System (INIS)

Maebara, S.; Imai, T.; Seki, M.; Suganuma, K.; Goniche, M.; Bibet, Ph.; Berio, S.; Brossaud, J.; Rey, G.; Tonon, G.

1997-03-01

A realistic antenna module using a poloidal divider for lower hybrid current drive (LHCD) experiment, is modelled and fabricated. In this antenna module test II, three types of poloidal dividers, which split the power in 3, are tested. (author)

Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

Science.gov (United States)

Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

2016-03-01

We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

Development of a surveillance robot for dimensional and visual inspection of fuel and reflector elements from the Fort St. Vrain HTGR

International Nuclear Information System (INIS)

Wallroth, C.F.; Marsh, N.I.; Miller, C.M.; Saurwein, J.J.; Smith, T.L.

1979-11-01

A robotic device has been developed for dimensional and visual inspection of irradiated HTGR core components. The robot consists of a rotary table and a two-finger probe, driven by stepping motors, and four remotely controlled television cameras. Automated operation is accomplished via minicomputer control. A total of 51 irradiated fuel and reflector elements were inspected at a fraction of the time and cost required for conventional methods

Enhancement of thermal neutron self-shielding in materials surrounded by reflectors

International Nuclear Information System (INIS)

Cornelia Chilian; Gregory Kennedy

2012-01-01

Materials containing from 41 to 1124 mg chlorine and surrounded by polyethylene containers of various thicknesses, from 0.01 to 5.6 mm, were irradiated in a research reactor neutron spectrum and the 38 Cl activity produced was measured as a function of polyethylene reflector thickness. For the material containing the higher amount of chlorine, the 38 Cl specific activity decreased with increasing reflector thickness, indicating increased neutron self-shielding. It was found that the amount of neutron self-shielding increased by as much as 52% with increasing reflector thickness. This is explained by neutrons which have exited the material subsequently reflecting back into it and thus increasing the total mean path length in the material. All physical and empirical models currently used to predict neutron self-shielding have ignored this effect and need to be modified. A method is given for measuring the adjustable parameter of a self-shielding model for a particular sample size and combination of neutron reflectors. (author)

Study of light collection uniformity dependence on reflector type in a large scintillation counter

International Nuclear Information System (INIS)

Astvatsaturov, R.G.; Ivanov, V.I.; Knapik, E.; Kramarenko, V.A.; Malakhov, A.I.; Khachaturyan, M.N.

1977-01-01

An investigation of the way to improve uniformity of light collection onto photoelectric multiplier photocathode, for the 100x10x2 cm scintillation counter, has been undertaken. Pulse amplitude versus the point, particles strike a scintillator, relationship, has been demonstrated for several types of reflectors. Used as reflectors were: white papar, aluminium foil, black papar and a combination of above reflectors. Experimental data analysis shows, that the combination of reflectors with different reflection coefficient, provides a means for 1,5 time improvement of counter light collection uniformity, with no impairment of amplitude characteristics

Performance of Cat's Eye Modulating Retro-Reflectors for Free-Space Optical Communications

National Research Council Canada - National Science Library

Rabinovich, W. S; Goetz, P. G; Mahon, R; Swingen, L; Murphy, J; Gilbreath, G. C; Binari, S; Waluschka, E

2004-01-01

Modulating retro-reflectors (MRR) couple passive optical retro-reflectors with electro-optic modulators to allow free-space optical communication with a laser and pointing/acquisition/tracking system required on only one end of the link...

Determination of antenna factors using a three-antenna method at open-field test site

Science.gov (United States)

Masuzawa, Hiroshi; Tejima, Teruo; Harima, Katsushige; Morikawa, Takao

1992-09-01

Recently NIST has used the three-antenna method for calibration of the antenna factor of an antenna used for EMI measurements. This method does not require the specially designed standard antennas which are necessary in the standard field method or the standard antenna method, and can be used at an open-field test site. This paper theoretically and experimentally examines the measurement errors of this method and evaluates the precision of the antenna-factor calibration. It is found that the main source of the error is the non-ideal propagation characteristics of the test site, which should therefore be measured before the calibration. The precision of the antenna-factor calibration at the test site used in these experiments, is estimated to be 0.5 dB.

Bottom reflector for power reactors

International Nuclear Information System (INIS)

Elter, C.; Kissel, K.F.; Schoening, J.; Schwiers, H.G.

1982-01-01

In pebble bed reactors erosion and damage due fuel elements movement on the surface of the bottom reflector should be minimized. This can be achieved by chamfering and/or rounding the cover edges of the graphite blocks and the edges between the drilled holes and the surface of the graphite block. (orig.) [de

Microwave monolithic integrated circuit development for future spaceborne phased array antennas

Science.gov (United States)

Anzic, G.; Kascak, T. J.; Downey, A. N.; Liu, D. C.; Connolly, D. J.

1984-01-01

The development of fully monolithic gallium arsenide (GaAs) receive and transmit modules suitable for phased array antenna applications in the 30/20 gigahertz bands is presented. Specifications and various design approaches to achieve the design goals are described. Initial design and performance of submodules and associated active and passive components are presented. A tradeoff study summary is presented, highlighting the advantages of a distributed amplifier approach compared to the conventional single power source designs. Previously announced in STAR as N84-13399

Microwave monolithic integrated circuit development for future spaceborne phased array antennas

Science.gov (United States)

Anzic, G.; Kascak, T. J.; Downey, A. N.; Liu, D. C.; Connolly, D. J.

The development of fully monolithic gallium arsenide (GaAs) receive and transmit modules suitable for phased array antenna applications in the 30/20 gigahertz bands is presented. Specifications and various design approaches to achieve the design goals are described. Initial design and performance of submodules and associated active and passive components are presented. A tradeoff study summary is presented, highlighting the advantages of a distributed amplifier approach compared to the conventional single power source designs. Previously announced in STAR as N84-13399

Living antennas on communication satellites

DEFF Research Database (Denmark)

Lumholt, Michael

2003-01-01

Crises change the global pattern of communication. The communications problems occur because the satellites are optimized to cover specific geographic areas, and these areas cannot be altered once the satellites are in Earth orbit. An effective solution to the problem is to equip communication sa...... satellites with "living" antennas that can adjust their radiation coverage areas according to the new demands. The development of living antennas is, therefore, among the focus areas identified and supported by the European Space Agency, ESA....

Initial global 2-D shielding analysis for the Advanced Neutron Source core and reflector

Energy Technology Data Exchange (ETDEWEB)

Bucholz, J.A.

1995-08-01

This document describes the initial global 2-D shielding analyses for the Advanced Neutron Source (ANS) reactor, the D{sub 2}O reflector, the reflector vessel, and the first 200 mm of light water beyond the reflector vessel. Flux files generated here will later serve as source terms in subsequent shielding analyses. In addition to reporting fluxes and other data at key points of interest, a major objective of this report was to document how these analyses were performed, the phenomena that were included, and checks that were made to verify that these phenomena were properly modeled. In these shielding analyses, the fixed neutron source distribution in the core was based on the `lifetime-averaged` spatial power distribution. Secondary gamma production cross sections in the fuel were modified so as to account intrinsically for delayed fission gammas in the fuel as well as prompt fission gammas. In and near the fuel, this increased the low-energy gamma fluxes by 50 to 250%, but out near the reflector vessel, these same fluxes changed by only a few percent. Sensitivity studies with respect to mesh size were performed, and a new 2-D mesh distribution developed after some problems were discovered with respect to the use of numerous elongated mesh cells in the reflector. All of the shielding analyses were performed sing the ANSL-V 39n/44g coupled library with 25 thermal neutron groups in order to obtain a rigorous representation of the thermal neutron spectrum throughout the reflector. Because of upscatter in the heavy water, convergence was very slow. Ultimately, the fission cross section in the various materials had to be artificially modified in order to solve this fixed source problem as an eigenvalue problem and invoke the Vondy error-mode extrapolation technique which greatly accelerated convergence in the large 2-D RZ DORT analyses. While this was quite effective, 150 outer iterations (over energy) were still required.

Initial global 2-D shielding analysis for the Advanced Neutron Source core and reflector

International Nuclear Information System (INIS)

Bucholz, J.A.

1995-08-01

This document describes the initial global 2-D shielding analyses for the Advanced Neutron Source (ANS) reactor, the D 2 O reflector, the reflector vessel, and the first 200 mm of light water beyond the reflector vessel. Flux files generated here will later serve as source terms in subsequent shielding analyses. In addition to reporting fluxes and other data at key points of interest, a major objective of this report was to document how these analyses were performed, the phenomena that were included, and checks that were made to verify that these phenomena were properly modeled. In these shielding analyses, the fixed neutron source distribution in the core was based on the 'lifetime-averaged' spatial power distribution. Secondary gamma production cross sections in the fuel were modified so as to account intrinsically for delayed fission gammas in the fuel as well as prompt fission gammas. In and near the fuel, this increased the low-energy gamma fluxes by 50 to 250%, but out near the reflector vessel, these same fluxes changed by only a few percent. Sensitivity studies with respect to mesh size were performed, and a new 2-D mesh distribution developed after some problems were discovered with respect to the use of numerous elongated mesh cells in the reflector. All of the shielding analyses were performed sing the ANSL-V 39n/44g coupled library with 25 thermal neutron groups in order to obtain a rigorous representation of the thermal neutron spectrum throughout the reflector. Because of upscatter in the heavy water, convergence was very slow. Ultimately, the fission cross section in the various materials had to be artificially modified in order to solve this fixed source problem as an eigenvalue problem and invoke the Vondy error-mode extrapolation technique which greatly accelerated convergence in the large 2-D RZ DORT analyses. While this was quite effective, 150 outer iterations (over energy) were still required

Analysis and test of a 16-foot radial rib reflector developmental model

Science.gov (United States)

Birchenough, Shawn A.

1989-01-01

Analytical and experimental modal tests were performed to determine the vibrational characteristics of a 16-foot diameter radial rib reflector model. Single rib analyses and experimental tests provided preliminary information relating to the reflector. A finite element model predicted mode shapes and frequencies of the reflector. The analyses correlated well with the experimental tests, verifying the modeling method used. The results indicate that five related, characteristic mode shapes form a group. The frequencies of the modes are determined by the relative phase of the radial ribs.

Modeling study on the thermal performance of a modified cavity receiver with glass window and secondary reflector

International Nuclear Information System (INIS)

Chang, Huawei; Duan, Chen; Wen, Ke; Liu, Yuting; Xiang, Can; Wan, Zhongmin; He, Sinian; Jing, Changwei; Shu, Shuiming

2015-01-01

Highlights: • A modified cavity receiver with glass window and secondary reflector is presented. • Optical and thermal performance of the modified cavity receiver is investigated. • Effects of glass window and secondary reflector are analyzed with comparison study. - Abstract: The development of a cavity receiver for a 1 kW beta type solar Stirling engine is presented in this work. The proposed receiver is composed of an additional quartz glass window and a secondary reflector aiming at improving the thermal performance. Monte-Carlo ray-tracing method is adopted to study the optical property and calculate radiative exchange factors of the solar collector system. The results show that the radiation flux sent to the proposed cavity receiver is 5003 W, and the optical efficiency of this receiver is 70.8%. Numerical simulation is conducted to investigate the thermal performance of this modified receiver. The proposed receiver is also compared with other three simulated receivers combining the presence and absence of the quartz glass window and the secondary reflector. The numerical simulation results show that the modified receiver with both quartz glass window and secondary trumpet reflector outperformed other designs, and its heat loss is reduced about 56% compared to the initial receiver without both quartz glass window and secondary reflector. Hence, the impact factors on the modified receiver radiation and convection heat transfer are well analyzed including temperature, the inner surface orientation and emissivity. The research indicates that the proposed cavity receiver can efficiently reduce the heat loss from cavity and is suitable for Stirling engine applications.

Performance Study of Screen-Printed Textile Antennas after Repeated Washing

Directory of Open Access Journals (Sweden)

Kazani I.

2014-06-01

Full Text Available The stability of wearable textile antennas after 20 reference washing cycles was evaluated by measuring the reflection coefficient of different antenna prototypes. The prototypes’ conductive parts were screen-printed on several textile substrates using two different silver-based conductive inks. The necessity of coating the antennas with a thermoplastic polyurethane (TPU coating was investigated by comparing coated with uncoated antennas. It is shown that covering the antennas with the TPU layer not only protects the screen-printed conductive area but also prevents delamination of the multilayered textile fabric substrates, making the antennas washable for up to 20 cycles. Furthermore, it is proven that coating is not necessary for maintaining antenna operation and this up to 20 washing cycles. However, connector detachment caused by friction during the washing process was the main problem of antenna performance degradation. Hence, other flexible, durable methods should be developed for establishing a stable electrical connection.

Quasi-optical millimeter wave rotating TE62 mode generator

International Nuclear Information System (INIS)

Li Shaopu; Zhang Conghui; Wang Zhong; Guo Feng; Chen Hongbin; Hu Linlin; Pan Wenwu

2011-01-01

The design,measurement technique and experimental results of rotating TE 6 2 mode generator are presented. The source includes millimeter wave optical system and open coaxial wave guide system. The millimeter wave optical system consists of pyramid antenna, hyperbolical reflector, parabolic reflector and quasi parabolic reflector. The open coaxial wave guide system contains open coaxial wave guide cavity, cylinder wave guide and output antenna. It is tested by network analyser and millimeter wave near field pattern auto-test system, and the purity of rotating TE 6 2 mode at 96.4 GHz is about 97%. (authors)

Unidirectional Magneto-Electric Dipole Antenna for Base Station: A Review

Science.gov (United States)

Idayachandran, Govindanarayanan; Nakkeeran, Rangaswamy

2018-04-01

Unidirectional base station antenna design using Magneto-Electric Dipole (MED) has created enormous interest among the researchers due to its excellent radiation characteristics like low back radiation, symmetrical radiation at E-plane and H-plane compared to conventional patch antenna. Generally, dual polarized antennas are used to increase channel capacity and reliability of the communication systems. In order to serve the evolving mobile communication standards like long term evolution LTE and beyond, unidirectional dual polarized MED antenna are required to have broad impedance bandwidth, broad half power beamwidth, high port isolation, low cross polarization level, high front to back ratio and high gain. In this paper, the critical electrical requirements of the base station antenna and frequently used frequency bands for modern mobile communication have been presented. It is followed by brief review on broadband patch antenna and discussion on complementary antenna concepts. Finally, the performance of linearly polarized and dual polarized magneto-electric dipole antennas along with their feeding techniques are discussed and summarized. Also, design and modeling of developed MED antenna is presented.

Large-Aperture Membrane Active Phased-Array Antennas

Science.gov (United States)

Karasik, Boris; McGrath, William; Leduc, Henry

2009-01-01

Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

Miniaturization of Multiple-Layer Folded Patch Antennas

DEFF Research Database (Denmark)

Zhang, Jiaying; Breinbjerg, Olav

2009-01-01

A new folded patch antenna with multiple layers was developed in this paper, by folding the patch in a proper way, and a highly miniaturized antenna can be realized. The multiple layer patch with 4-layer and 6-layer are designed and evaluated at 2.4 GHz, 915 MHz, and 415 MHz respectively. Then a 4...... layer patch is fabricated and measured to validate the design method. The theoretical analysis, design and simulations, fabrications, as well as the measurements are presented in this paper. All the results show that the folded patch antenna is a good candidate in making a highly miniaturized compact...

Large Deployable Reflector (LDR) feasibility study update

Science.gov (United States)

Alff, W. H.; Banderman, L. W.

1983-01-01

In 1982 a workshop was held to refine the science rationale for large deployable reflectors (LDR) and develop technology requirements that support the science rationale. At the end of the workshop, a set of LDR consensus systems requirements was established. The subject study was undertaken to update the initial LDR study using the new systems requirements. The study included mirror materials selection and configuration, thermal analysis, structural concept definition and analysis, dynamic control analysis and recommendations for further study. The primary emphasis was on the dynamic controls requirements and the sophistication of the controls system needed to meet LDR performance goals.

Albedo-adjusted fast-neutron diffusion coefficients in reactor reflectors

International Nuclear Information System (INIS)

Terney, W.B.

1975-01-01

In the newer, larger pressurized-water reactor cores, the calculated power distributions are fairly sensitive to the number of neutron groups used and to the treatment of the reflector cross sections. Comparisons between transport and diffusion calculations show that the latter substantially underpredict the reflector albedos in the fast (top) group and that the power distribution is shifted toward the core center when compared to 4-group transport theory results. When the fast-neutron diffusion coefficients are altered to make the transport- and diffusion-theory albedos agree, the power distributions are also brought into agreement. An expression for the fast-neutron diffusion coefficients in reflector regions has been derived such that the diffusion calculation reproduces the albedo obtained from a transport solution. In addition, a correction factor for mesh effects applicable to coarse mesh problems is presented. The use of the formalism gives the correct albedos and improved power distributions. (U.S.)

Performance improvement of the finned passive PVT system using reflectors like removable insulation covers

International Nuclear Information System (INIS)

Ziapour, Behrooz M.; Palideh, Vahid; Mokhtari, Farhad

2016-01-01

Highlights: • A passive PVT system means the combination of a PV panel and a compact solar water heater. • Comparative study was done on performance characteristics in passive and hybrid PVT systems. • Reflectors effects on performance of a finned passive PVT system were numerically studied. • Results show that the finned passive PVT system has higher performance than the hybrid type. • Reflectors reduce the night heat losses and increase the solar radiation rate on PVT system. - Abstract: A passive photovoltaic–thermal system (PVT) is the combination of a photovoltaic (PV) panel and a compact solar water heater for co-generation of heat and electricity. This system bears considerable heat losses to ambient, particularly at noncollection times. One simple way to overcome this problem is to use a removable insulation cover on the collector's outer glazing. In this paper, the effects of the reflectors on day and night performance of a finned passive PVT system were numerically studied. At nonenergy collection time, the reflectors can turn and cover the collector cover glass as a nonconductor material. Simulation results showed that the reflectors reduce the night heat losses and increase the solar radiation rate on the absorber plate. The use of removable insulation reflectors resulted to saving extra sensibly thermal energy. Also, the solar cells power generation (P_s_c), in the case of reflectors installed, was reinforced.

Smart antennas in aerospace applications

NARCIS (Netherlands)

Verpoorte, Jaco; Schippers, Harmen; Roeloffzen, C.G.H.; Marpaung, D.A.I.

2010-01-01

The interest in Smart Antennas for aerospace applications is growing. This paper describes smart antennas which can be used on aircraft. Two aerospace applications are discussed in more detail: a phased array antenna with optical beam forming and a large vibrating phased array antenna with

History of Antenna Technology for Mobile Communications in Korea

Science.gov (United States)

Min, Kyeong-Sik; Park, Chul-Keun; Kang, Suk-Youb

In this paper, we discuss the development of wireless and mobile communications in Korea, current technological trends, and the future outlook on technological developments. Since the introduction of the telegraph and the telephone in September 1885, Korea's wired and wireless communications industry has consistently developed for over 100 years. Since 1984, upon the provision of the mobile telecommunications service, the industry has seen drastic qualitative and quantitative growth in terms of both technical and economic aspects, which played a crucial role in the rapid growth of the digital industry in Korea. After the era of the analog cellular service based on the Advanced Mobile Phone System (AMPS), a precursor to the modern mobile service, Korea became the world's first country to commercialize Code Division Multiple Access (CDMA) in 1996 and succeeded in commercializing CDMA 2000 lx (IMT 2000) in 2001. With further developments in the mobile communication technology, the technology for antennas also saw drastic advancements. As the mobile antennas moved from the second to the third generation, they grew from external models to very small internal models. At the same time, they evolved into highly functional and high performance multiple band and wide band antennas. Furthermore, Korea was the first country to commercialize and offer the Wireless Broadband Internet (WiBro) service in 2006. By leading the wireless communications standardization and exerting remarkable efforts in research and development, Korea is consolidating its status as an Information Technology (IT) leader in the global market. The antenna's inherent importance will be further emphasized in the near future as it satisfies the performance and structural needs of portable terminals necessary for realizing the projected establishment of the ubiquitous world. It is thought that antenna technologies will not be limited to simple concepts as previously experienced but will utilize various kinds

Antenna for Ultrawideband Channel Sounding

DEFF Research Database (Denmark)

Zhekov, Stanislav Stefanov; Tatomirescu, Alexandru; Pedersen, Gert F.

2016-01-01

A novel compact antenna for ultrawideband channel sounding is presented. The antenna is composed of a symmetrical biconical antenna modified by adding a cylinder and a ring to each cone. A feeding coaxial cable is employed during the simulations in order to evaluate and reduce its impact on the a......A novel compact antenna for ultrawideband channel sounding is presented. The antenna is composed of a symmetrical biconical antenna modified by adding a cylinder and a ring to each cone. A feeding coaxial cable is employed during the simulations in order to evaluate and reduce its impact...

All-dielectric rod antenna array for terahertz communications

Science.gov (United States)

Withayachumnankul, Withawat; Yamada, Ryoumei; Fujita, Masayuki; Nagatsuma, Tadao

2018-05-01

The terahertz band holds a potential for point-to-point short-range wireless communications at sub-terabit speed. To realize this potential, supporting antennas must have a wide bandwidth to sustain high data rate and must have high gain and low dissipation to compensate for the free space path loss that scales quadratically with frequency. Here we propose an all-dielectric rod antenna array with high radiation efficiency, high gain, and wide bandwidth. The proposed array is integral to a low-loss photonic crystal waveguide platform, and intrinsic silicon is the only constituent material for both the antenna and the feed to maintain the simplicity, compactness, and efficiency. Effective medium theory plays a key role in the antenna performance and integrability. An experimental validation with continuous-wave terahertz electronic systems confirms the minimum gain of 20 dBi across 315-390 GHz. A demonstration shows that a pair of such identical rod array antennas can handle bit-error-free transmission at the speed up to 10 Gbit/s. Further development of this antenna will build critical components for future terahertz communication systems.

Improvement of Axial Reflector Cross Section Generation Model for PWR Core Analysis

Energy Technology Data Exchange (ETDEWEB)

Shim, Cheon Bo; Lee, Kyung Hoon; Cho, Jin Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

This paper covers the study for improvement of axial reflector XS generation model. In the next section, the improved 1D core model is represented in detail. Reflector XS generated by the improved model is compared to that of the conventional model in the third section. Nuclear design parameters generated by these two XS sets are also covered in that section. Significant of this study is discussed in the last section. Two-step procedure has been regarded as the most practical approach for reactor core designs because it offers core design parameters quite rapidly within acceptable range. Thus this approach is adopted for SMART (System-integrated Modular Advanced Reac- Tor) core design in KAERI with the DeCART2D1.1/ MASTER4.0 (hereafter noted as DeCART2D/ MASTER) code system. Within the framework of the two-step procedure based SMART core design, various researches have been studied to improve the core design reliability and efficiency. One of them is improvement of reflector cross section (XS) generation models. While the conventional FA/reflector two-node model used for most core designs to generate reflector XS cannot consider the actual configuration of fuel rods that intersect at right angles to axial reflectors, the revised model reflects the axial fuel configuration by introducing the radially simplified core model. The significance of the model revision is evaluated by observing HGC generated by DeCART2D, reflector XS, and core design parameters generated by adopting the two models. And it is verified that about 30 ppm CBC error can be reduced and maximum Fq error decreases from about 6 % to 2.5 % by applying the revised model. Error of AO and axial power shapes are also reduced significantly. Therefore it can be concluded that the simplified 1D core model improves the accuracy of the axial reflector XS and leads to the two-step procedure reliability enhancement. Since it is hard for core designs to be free from the two-step approach, it is necessary to find

Microwave RF antennas and circuits nonlinearity applications in engineering

CERN Document Server

Aluf, Ofer

2017-01-01

This book describes a new concept for analyzing RF/microwave circuits, which includes RF/microwave antennas. The book is unique in its emphasis on practical and innovative microwave RF engineering applications. The analysis is based on nonlinear dynamics and chaos models and shows comprehensive benefits and results. All conceptual RF microwave circuits and antennas are innovative and can be broadly implemented in engineering applications. Given the dynamics of RF microwave circuits and antennas, they are suitable for use in a broad range of applications. The book presents analytical methods for microwave RF antennas and circuit analysis, concrete examples, and geometric examples. The analysis is developed systematically, starting with basic differential equations and their bifurcations, and subsequently moving on to fixed point analysis, limit cycles and their bifurcations. Engineering applications include microwave RF circuits and antennas in a variety of topological structures, RFID ICs and antennas, micros...

One- and two-dimensional antenna arrays for microwave wireless power transfer (MWPT) systems and dual-antenna transceivers

Science.gov (United States)

Lin, Yo-Sheng; Hu, Chun-Hao; Chang, Chi-Ho; Tsao, Ping-Chang

2018-06-01

In this work, we demonstrate novel one-dimensional (1D) and two-dimensional (2D) antenna arrays for both microwave wireless power transfer (MWPT) systems and dual-antenna transceivers. The antenna array can be used as the MWPT receiving antenna of an integrated MWPT and Bluetooth (BLE) communication module (MWPT-BLE module) for smart CNC (computer numerical control) spindle incorporated with the cloud computing system SkyMars. The 2D antenna array has n rows of 1 × m 1D array, and each array is composed of multiple (m) differential feeding antenna elements. Each differential feeding antenna element is a differential feeding structure with a microstrip antenna stripe. The stripe length is shorter than one wavelength to minimise the antenna area and to prevent being excited to a high-order mode. That is, the differential feeding antenna element can suppress the even mode. The mutual coupling between the antenna elements can be suppressed, and the isolation between the receiver and the transmitter can be enhanced. An inclination angle of the main beam aligns with the broadside, and the main beam is further concentrated and shrunk at the elevation direction. Moreover, if more differential feeding antenna elements are used, antenna gain and isolation can be further enhanced. The excellent performance of the proposed antenna arrays indicates that they are suitable for both MWPT systems and dual-antenna transceivers.

Bifacial PV cell with reflector for stand-alone mast for sensor powering purposes

Science.gov (United States)

Jakobsen, Michael L.; Thorsteinsson, Sune; Poulsen, Peter B.; Riedel, N.; Rødder, Peter M.; Rødder, Kristin

2017-09-01

Reflectors to bifacial PV-cells are simulated and prototyped in this work. The aim is to optimize the reflector to specific latitudes, and particularly northern latitudes. Specifically, by using minimum semiconductor area the reflector must be able to deliver the electrical power required at the condition of minimum solar travel above the horizon, worst weather condition etc. We will test a bifacial PV-module with a retroreflector, and compare the output with simulations combined with local solar data.

Investigation of the crack in a reflector element of JRR-4

International Nuclear Information System (INIS)

2008-09-01

The JRR-4 (Japan Research Reactor No.4) has been used as a shared utilization facility for many researches since the first criticality in January 1965. A crack was ascertained on a weld area of one reflector element on December 28, 2007. The Department of Research Reactor and Tandem Accelerator set up an ad hoc working group of experts in the JAEA (Japan Atomic Energy Agency), and investigated cause of crack on the weld area. The following examinations were carried out; visual examination, dimensional examination, fractography examination and so on. It was concluded that the main cause of the crack is the swelling of graphite in the reflector element. The swelling must be due to neutron irradiation. We carried out a radiografical examination of the other reflector elements. As the result, we determined that many of them were not in a suitable state to be used because of swelling of graphite. The design of the new reflector elements should be carried out, based on the relation between the irradiation does and swelling rate, which has been obtained in these investigation. (author)

Low-Profile, Dual-Wavelength, Dual-Polarized Antenna

Science.gov (United States)

Carswell, James R.

2010-01-01

A single-aperture, low-profile antenna design has been developed that supports dual-polarization and simultaneous operation at two wavelengths. It realizes multiple beams in the elevation plane, and supports radiometric, radar, and conical scanning applications. This antenna consists of multiple azimuth sticks, with each stick being a multilayer, hybrid design. Each stick forms the h-plane pattern of the C and Ku-band vertically and horizontally polarized antenna beams. By combining several azimuth sticks together, the elevation beam is formed. With a separate transceiver for each stick, the transmit phase and amplitude of each stick can be controlled to synthesize a beam at a specific incidence angle and to realize a particular side-lobe pattern. By changing the transmit phase distribution through the transceivers, the transmit antenna beam can be steered to different incidence angles. By controlling the amplitude distribution, different side lobe patterns and efficiencies can be realized. The receive beams are formed using digital beam synthesis techniques, resulting in very little loss in the receive path, thus enabling a very-low loss receive antenna to support passive measurements.

Antenna-coupled bolometer arrays using transition-edge sensors

Energy Technology Data Exchange (ETDEWEB)

Myers, Michael J. [Department of Physics, University of California, Berkeley, California 94720 (United States)]. E-mail: mmyers@cosmology.berkeley.edu; Ade, Peter [School of Physics and Astronomy, Cardiff University, Cardiff, Wales (United Kingdom); Arnold, Kam [Department of Physics, University of California, Berkeley, California 94720 (United States); Engargiola, Greg [Department of Astronomy, University of California, Berkeley, California 94720 (United States); Holzapfel, Bill [Department of Physics, University of California, Berkeley, California 94720 (United States); Lee, Adrian T. [Department of Physics, University of California, Berkeley, California 94720 (United States); O' Brient, Roger [Department of Physics, University of California, Berkeley, California 94720 (United States); Richards, Paul L. [Department of Physics, University of California, Berkeley, California 94720 (United States); Smith, Andy [Northrop Grumman, Redondo Beach, California 90278 (United States); Spieler, Helmuth [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Tran, Huan T. [Department of Physics, University of California, Berkeley, California 94720 (United States)

2006-04-15

We are developing antenna-coupled Transition-Edge Sensor (TES) bolometer arrays for use in measurements of the CMB polarization. TES bolometers have many well-known advantages over conventional bolometers, such as increased speed, linearity, and the existence of readout multiplexers. Antenna-coupled bolometers use an on-chip planar antenna to couple light into the bolometer. The antenna directivity and polarization sensitivity, along with the potential for on-chip band defining filters and channelizing circuits, allow a significant increase in focal plane integration. This eliminates the bulky horns, quasioptical filters, dichroics, and polarizers which might otherwise be needed in a conventional bolometric system. This simplification will ease the construction of receivers with larger numbers of pixels. We report on the fabrication and optical testing of single antenna-coupled bolometer pixels with integrated band defining filters. We will also discuss current progress on fabrication of a bolometer array based on this design.

Design of the Graphite Reflectors in Research Reactors

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Haeng; Cho, Yeong Garp; Kim, Tae Kyu; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

Graphite is often used as one of reflector materials for research reactors because of its low neutron absorption cross-section, good moderating properties, and relatively low and stable price. In addition, graphite has excellent properties at high temperatures, so it is widely used as a core material in high temperature reactors. However, its material characteristics such as strength, elastic modulus, thermal expansion coefficient, dimensional change, and thermal conductivity sensitively depend on neutron fluence, temperature, and its manufacturing process. In addition, the Wigner energy and the treatment of the graphite waste such as C-14 should also be considered. For the design of the graphite reflectors, it is therefore essential to understand the material characteristics of chosen graphite materials at given conditions. Especially, the dimensional changes and the thermal conductivity are very important factors to design the nuclear components using graphite as a nonstructural material. Hence, in this study, the material characteristics of graphite are investigated via some experiments in literature. Improving design methods for graphite reflectors in research reactors are then suggested to minimize the problems, and the advantages and disadvantages of each method are also discussed

Microstrip patch antenna for simultaneous strain and temperature sensing

Science.gov (United States)

Mbanya Tchafa, F.; Huang, H.

2018-06-01

A patch antenna, consisting of a radiation patch, a dielectric substrate, and a ground plane, resonates at distinct fundamental frequencies that depend on the substrate dielectric constant and the dimensions of the radiation patch. Since these parameters change with the applied strain and temperature, this study investigates simultaneous strain and temperature sensing using a single antenna that has two fundamental resonant frequencies. The theoretical relationship between the antenna resonant frequency shifts, the temperature, and the applied strain was first established to guide the selection of the dielectric substrate, based on which an antenna sensor with a rectangular radiation patch was designed and fabricated. A tensile test specimen instrumented with the antenna sensor was subjected to thermo-mechanical tests. Experiment results validated the theoretical predictions that the normalized antenna resonant frequency shifts are linearly proportional to the applied strain and temperature changes. An inverse method was developed to determine the strain and temperature changes from the normalized antenna resonant frequency shifts, yielding measurement uncertainty of 0.4 °C and 17.22 μ \\varepsilon for temperature and strain measurement, respectively.

SAR antenna design for ambiguity and multipath suppression

DEFF Research Database (Denmark)

Christensen, Erik Lintz; Dich, Mikael

1993-01-01

A high resolution airborne synthetic aperture radar (SAR) has been developed at the Electromagnetics Institute (EMI) for remote sensing applications. The paper considers the radiation of antennas for a SAR system from a systems perspective. The basic specifications of an idealised antenna...... are obtained from the required swath and the azimuth footprint needed for the SAR processing. The radiation from a real antenna causes unwanted signal returns that lead to intensity variations (multipath) and ghost echoes (ambiguity). Additional specifications are deduced by considering these signals...

Optically addressed ultra-wideband phased antenna array

Science.gov (United States)

Bai, Jian

Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization

Analysis of the stress-deformed condition of the disassembly parabolic antenna

Science.gov (United States)

Odinets, M. N.; Kaygorodtseva, N. V.; Krysova, I. V.

2018-01-01

Active development of satellite communications and computer-aided design systems raises the problem of designing parabolic antennas on a new round of development. The aim of the work was to investigate the influence of the design of the mirror of a parabolic antenna on its endurance under wind load. The research task was an automated analysis of the stress-deformed condition of various designs of computer models of a paraboloid mirror (segmented or holistic) at modeling the exploitation conditions. The peculiarity of the research was that the assembly model of the antenna’s mirror was subjected to rigid connections on the contacting surfaces of the segments and only then the finite element grid was generated. The analysis showed the advantage of the design of the demountable antenna, which consists of cyclic segments, in front of the construction of the holistic antenna. Calculation of the stress-deformed condition of the antennas allows us to conclude that dividing the design of the antenna’s mirror on parabolic and cyclic segments increases it strength and rigidity. In the future, this can be used to minimize the mass of antenna and the dimensions of the disassembled antenna. The presented way of modeling a mirror of a parabolic antenna using to the method of the finite-element analysis can be used in the production of antennas.

Heavy reflector experiments in the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Santos, Adimir dos; Silva, Graciete Simoes de Andrade e; Mura, Luis Felipe; Fuga, Rinaldo; Jerez, Rogerio; Mendonca, Arlindo Gilson

2012-01-01

Full text: The heavy reflector experiments performed in the IPEN/MB-01 research reactor facility comprise a set of critical configurations employing the standard 28x26-fuel-rod configuration. The heavy reflector either Stainless Steel, Carbon Steel or Nickel plates was placed at one of the faces of the IPEN/MB-01 reactor. Criticality is achieved by inserting the control banks BC1 and BC2 to the critical position. 32 plates around 0.3 mm thick were used in the experiment. The chosen distance between last fuel rod row and the first laminate for both type of laminates was 5.5 mm. Considering initially the SS case, the experimental data reveal that the reactivity decreases up to the sixth plate and after that it increases, becomes nearly zero (which was equivalent to initial zero excess reactivity with zero plates) for the 21 plates case and reaches a value of 154.91 pcm when the whole set of 32 plates are inserted in the reflector. This is a very striking result because it demonstrates that when all 32 plates are inserted in the reflector there is a net gain of reactivity. The reactivity behavior demonstrates all the physics events already mentioned in this work. When the number of plates are small (around 6), the neutron absorption in the plates is more important than the neutron reflection and the reactivity decreases. This condition holds up to a point where the neutron reflection becomes more important than the neutron absorption in the plates and the reactivity increases. The experimental data for the Carbon Steel and Nickel case shows the main features of the SS case, but for the Carbon Steel case the reactivity gain is small, thus demonstrating that Carbon Steel or essentially iron has not the reflector capability as the SS laminates do. The measured data of Nickel plates show a higher reactivity gain, thus demonstrating that Nickel is a good reflector. The theoretical analysis employing MCNP5 and ENDF/B-VII.0 show that the SS calculated results are in a good

Uranium Enrichment Reduction in the Prototype Gen-IV Sodium-Cooled Fast Reactor (PGSFR with PBO Reflector

Directory of Open Access Journals (Sweden)

Chihyung Kim

2016-04-01

Full Text Available The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

Uranium enrichment reduction in the Prototype Gen-IV sodium-cooled fast reactor (PGSFR) with PBO reflector

Energy Technology Data Exchange (ETDEWEB)

Hartanto, Donny; Kim, Chi Hyung; Kim, Yong Hee [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of)

2016-04-15

The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR) is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

New two-port multimode interference reflectors

NARCIS (Netherlands)

Kleijn, E.; Smit, M.K.; Wale, M.J.; Leijtens, X.J.M.

2012-01-01

Multi-mode interference reflectors (MIRs) are versatile components. Two new MIR designs with a fixed 50/50 reflection to transmission ratio are introduced. Measurements on these new devices and on devices similar to those in [1] are presented and compared to the design values. Measured losses are

Antenna theory analysis and design

CERN Document Server

Balanis, Constantine A

2005-01-01

The discipline of antenna theory has experienced vast technological changes. In response, Constantine Balanis has updated his classic text, Antenna Theory, offering the most recent look at all the necessary topics. New material includes smart antennas and fractal antennas, along with the latest applications in wireless communications. Multimedia material on an accompanying CD presents PowerPoint viewgraphs of lecture notes, interactive review questions, Java animations and applets, and MATLAB features. Like the previous editions, Antenna Theory, Third Edition meets the needs of e

Deployable reflector configurations. [for space telescope

Science.gov (United States)

Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

1983-01-01

Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

A New Fractal-Based Miniaturized Dual Band Patch Antenna for RF Energy Harvesting

Directory of Open Access Journals (Sweden)

Sika Shrestha

2014-01-01

Full Text Available The growth of wireless communications in recent years has made it necessary to develop compact, lightweight multiband antennas. Compact antennas can achieve the same performance as large antennas do with low price and with greater system integration. Dual-frequency microstrip antennas for transmission and reception represent promising approach for doubling the system capacity. In this work, a miniaturized dual band antenna operable at 2.45 and 5.8 GHz is constructed by modifying the standard microstrip patch antenna geometry into a fractal structure. In addition to miniaturization and dual band nature, the proposed antenna also removes unwanted harmonics without the use of additional filter component. Using a finite-element-method-based high frequency structure simulator (HFSS, the antenna is designed and its performance in terms of return loss, impedance matching, radiation pattern, and voltage standing wave ratio (VSWR is demonstrated. Simulation results are shown to be in close agreement with performance measurements from an actual antenna fabricated on an FR4 substrate. The proposed antenna can be integrated with a rectifier circuit to develop a compact rectenna that can harvest RF energy in both of these frequency bands at a reduction in size of 25.98% relative to a conventional rectangular patch antenna.

Value Engineering and Function Analysis: Frameworks for Innovation in Antenna Systems

Directory of Open Access Journals (Sweden)

Hamid Reza Fartookzadeh

2018-04-01

Full Text Available Value engineering (VE and function analysis (FA are technological tools for the functional enhancement and cost reduction of engineering projects. They also help to overcome mental inertia by acknowledging the voice of the customer in complicated systems. Antenna engineering, providing electromagnetic remote links, is an important area in engineering science, with a large number of innovative concepts. However, managing innovative ideas to improve performance, reliability, quality, safety, and reduce life cycle costs, is still a work in progress. This research was designed to apply VE and FA as frameworks for innovative ideas in antenna systems, especially with regard to imaging and radar systems. FA diagrams free a designers’ mind from tools to instead focus on purpose, which can help them to obtain better ideas for solutions to problems. It was identified that there were several options available for functionality enhancement and cost reduction. The required functionalities of the components of antenna systems, and their advantages and limitations were indicated. In addition, it was identified that some of the advantages and limitations appeared for combinations of the components. Alternative methods for applications, such as polarization conversion and the separation of outgoing and incoming electromagnetic waves, were studied. Circular polarization (CP is important for two-way communication, since left-handed circularly polarized waves usually return with right-handed CP from targets. Therefore, various methods for producing CP were discussed, such as metamaterial-based linear to circular polarization converters and waveguide polarizers. Also, potential extra applications for these systems were explained. Two examples were: (1 merging multiple systems with different operating frequencies using multiband components; and (2 applying a feeding system for multiple reflectors using surfaces that reflect half of the wave and transmit the other

3D electromagnetic theory of ICRF multi PORT multi loop antenna

International Nuclear Information System (INIS)

Vdovin, V.L.; Kamenskij, I.V.

1997-01-01

In this report the theory of three dimensional antenna in Ion Cyclotron Resonance Frequency (ICRF) is developed for a plasma with circular magnetic surfaces. The multi loop antenna is located in ITER several ports. Circular plasma and antenna geometry provides new important tools to account for: 1) right loading antenna impedance matrix calculation urgently needed for a matching of RF generator with an antenna; 2) right calculation of an antenna toroidal and poloidal excited spectra because the DIFFRACTION, refraction and REFLECTION effects for the Fast Waves (FW) are in FIRST time are included self consistently in 3D ICRF antenna - plasma treatment; 3) right calculation of RF power deposition profiles because self consistently found 3D antenna - plasma FW excited spectra in non slab plasma model are important ones in a weakly dissipated plasma for Fast Waves (even for ITER parameters). (J.P.N.)

Multi-antenna synthetic aperture radar

CERN Document Server

Wang, Wen-Qin

2013-01-01

Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

Current Monitoring System for ITER Like ICRH Antenna

International Nuclear Information System (INIS)

Argouarch, A.

2006-01-01

On TS antennas, the power transfer optimization from ICRH antenna to Plasma load is performed using feedback internal matching system. Experimental handling is required to mach the reactive impedance accordingly to the fluctuant plasma loading. As part of the development of the new ICRH prototype antenna, an additional measurement system based on Rogowski coils was developed to monitor the current distribution in antenna straps. The objective is to control module and phase of the antenna current straps with measurement provided by the coil system. Matching capacitors values, generators power and phase can also be controlled using the output of the devices, improving the real time matching control of the array. This paper details the new measurement layout, the Rogowski coil, and the whole system connected on each strap design for RF currents measurement between 40 MHz - 60 MHz for maximum amplitude of 1 kA. On the new ICRH prototype antenna, the measurement coils are coupled to the point where the strap currents are short circuited to the frame. The module and phase measurements are performed with the coils by direct magnetic induction in a vacuum and high temperature environment. Also, the Rogowski coils were characterized at low level power with vector network analyzer and the design adapted in order to obtain a controlled and reproducible gain in the desire bandwidth. The transconductive function is established with an experimental gain near -80 dB between primary circuit and inductive signal generated by the Rogowski coil. In a second step, the system with its associated electronic was qualified under high RF power. First results with high RF current (closed to 500 A at 57 MHz) match the desire Rogowski coil response. Compromises with electrical response at low power level and the coil under thermal/RF stresses were the most challenging part of the development. The overall response of the system and the current module/phase measurements are promising. A proper

From antenna to antenna: lateral shift of olfactory memory recall by honeybees.

Science.gov (United States)

Rogers, Lesley J; Vallortigara, Giorgio

2008-06-04

Honeybees, Apis mellifera, readily learn to associate odours with sugar rewards and we show here that recall of the olfactory memory, as demonstrated by the bee extending its proboscis when presented with the trained odour, involves first the right and then the left antenna. At 1-2 hour after training using both antennae, recall is possible mainly when the bee uses its right antenna but by 6 hours after training a lateral shift has occurred and the memory can now be recalled mainly when the left antenna is in use. Long-term memory one day after training is also accessed mainly via the left antenna. This time-dependent shift from right to left antenna is also seen as side biases in responding to odour presented to the bee's left or right side. Hence, not only are the cellular events of memory formation similar in bees and vertebrate species but also the lateralized networks involved may be similar. These findings therefore seem to call for remarkable parallel evolution and suggest that the proper functioning of memory formation in a bilateral animal, either vertebrate or invertebrate, requires lateralization of processing.

From antenna to antenna: lateral shift of olfactory memory recall by honeybees.

Directory of Open Access Journals (Sweden)

Lesley J Rogers

Full Text Available Honeybees, Apis mellifera, readily learn to associate odours with sugar rewards and we show here that recall of the olfactory memory, as demonstrated by the bee extending its proboscis when presented with the trained odour, involves first the right and then the left antenna. At 1-2 hour after training using both antennae, recall is possible mainly when the bee uses its right antenna but by 6 hours after training a lateral shift has occurred and the memory can now be recalled mainly when the left antenna is in use. Long-term memory one day after training is also accessed mainly via the left antenna. This time-dependent shift from right to left antenna is also seen as side biases in responding to odour presented to the bee's left or right side. Hence, not only are the cellular events of memory formation similar in bees and vertebrate species but also the lateralized networks involved may be similar. These findings therefore seem to call for remarkable parallel evolution and suggest that the proper functioning of memory formation in a bilateral animal, either vertebrate or invertebrate, requires lateralization of processing.

Design and performance of the ALMA-J prototype antenna

Science.gov (United States)

Ukita, Nobuharu; Saito, Masao; Ezawa, Hajime; Ikenoue, Bungo; Ishizaki, Hideharu; Iwashita, Hiroyuki; Yamaguchi, Nobuyuki; Hayakawa, Takahiro

2004-10-01

The National Astronomical Observatory of Japan has constructed a prototype 12-m antenna of the Atacama Compact Array to evaluate its performance at the ALMA Test Facility in the NRAO VLA observatory in New Mexico, the United States. The antenna has a CFRP tube backup structure (BUS) with CFRP boards to support 205 machined Aluminum surface panels. Their accuracies were measured to be 5.9 m rms on average. A chemical treatment technique of the surface panels has successfully applied to scatter the solar radiation, which resulted in a subreflector temperature increase of about 25 degrees relative to ambient temperature during direct solar observations. Holography measurements and panel adjustments led to a final surface accuracy of 20 m rms, (weighted by 12dB edge taper), after three rounds of the panel adjustments. Based on a long term temperature monitoring of the BUS and thermal deformation FEM calculation, the BUS thermal deformation was estimated to be less than 3.1 m rms. We have employed gear drive mechanism both for a fast position switching capability and for smooth drive at low velocities. Servo errors measured with angle encoders were found to be less than 0.1 arcseconds rms at rotational velocities below 0.1 degrees s-1 and to increase to 0.7 arcseconds rms at the maximum speed of the 'on-the-fly' scan as a single dish, 0.5 deg s-1 induced by the irregularity of individual gear tooth profiles. Simultaneous measurements of the antenna motion with the angle encoders and seismic accelerometers mounted at the primary reflector mirror edges and at the subreflector showed the same amplitude and phase of oscillation, indicating that they are rigid, suggesting that it is possible to estimate where the antenna is actually pointing from the encoder readout. Continuous tracking measurements of Polaris during day and night have revealed a large pointing drift due to thermal distortion of the yoke structure. We have applied retrospective thermal corrections to

Experimental Study on RFID Antenna Reading Areas in a Tunnel System

Directory of Open Access Journals (Sweden)

Kai Kordelin

2017-01-01

Full Text Available We study optimized antenna reading area mappings for a radiofrequency identification- (RFID- based access monitoring system, used in an underground nuclear waste storage facility. We shortly introduce the access monitoring system developed for the ONKALO tunnel in Finland and describe the antenna mounting points as well as the research area. Finally, we study the measurement results of the antenna reading areas and factors that affect the reading area size. Based on our results, in addition to antenna location and direction, absorption to obstacles, reflections, diffraction, scattering, and refraction affect the antenna reading area.

Antenna subset selection at multi-antenna relay with adaptive modulation

KAUST Repository

Choi, Seyeong

2011-06-01

In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

Antenna subset selection at multi-antenna relay with adaptive modulation

KAUST Repository

Choi, Seyeong; Hasna, Mazen Omar; Yang, Hongchuan; Alouini, Mohamed-Slim

2011-01-01

In this paper, we proposed several antenna selection schemes for cooperative diversity systems with adaptive transmission. The proposed schemes were based on dual-hop relaying where a relay with multiple-antenna capabilities at reception and transmission is deployed between the source and the destination nodes. We analyzed the performance of the proposed schemes by quantifying the average spectral efficiency and the outage probability. We also investigated the trade-off of performance and complexity by comparing the average number of active antennas, path estimations, and signal-to-noise ratio comparisons of the different proposed schemes. Copyright © 2011 John Wiley & Sons, Ltd.

Global shielding analysis of the 2-element ANS core and reflector with photoneutrons

International Nuclear Information System (INIS)

Bucholz, J.A.

1996-01-01

This paper describes the initial global 2-D shielding analyses for the 2-element, heavy-water cooled and reflected Advanced Neutron Source reactor which was to have been built in Oak Ridge, Tennessee. The portion of the system analyzed encompassed the highly enriched core, the 1.5-m-thick heavy-water reflector, the aluminum reflector vessel, and the first 0.2 m of light water beyond the reflector vessel. While some results are presented, this paper focuses primarily on the lessons learned during the analysis of this rather unique system

Dual-Beam Antenna Design for Autonomous Sensor Network Applications

Directory of Open Access Journals (Sweden)

Jean-Marie Floc'h

2012-01-01

Full Text Available This paper describes our contribution in the ANR project called CAPNET dedicated to the site security (autonomous sensor network. The network is autonomous in term of energy and it is very easy to deploy on the site (the time to deploy each node of the network is around 10 minutes. The first demonstrator was deployed in the fire base station of Brest, France with 10 nodes with a security perimeter around 1.5 km. Our contribution takes place in the field of antennas, with the development of two systems: a single-beam antenna reserved for the supervisor or the last node of the network, and a dual-beam antenna dedicated to the node in linear configuration. For the design and optimization of antennas, we use HFSS CAD software from ANSOFT. The antennas have been designed and successfully measured.

Antenna Design Considerations for the Advanced Extravehicular Mobility Unit

Science.gov (United States)

Bakula, Casey J.; Theofylaktos, Onoufrios

2015-01-01

NASA is designing an Advanced Extravehicular Mobility Unit (AEMU)to support future manned missions beyond low-Earth orbit (LEO). A key component of the AEMU is the communications assembly that allows for the wireless transfer of voice, video, and suit telemetry. The Extravehicular Mobility Unit (EMU) currently used on the International Space Station (ISS) contains a radio system with a single omni-directional resonant cavity antenna operating slightly above 400 MHz capable of transmitting and receiving data at a rate of about 125 kbps. Recent wireless communications architectures are calling for the inclusion of commercial wireless standards such as 802.11 that operate in higher frequency bands at much higher data rates. The current AEMU radio design supports a 400 MHz band for low-rate mission-critical data and a high-rate band based on commercial wireless local area network (WLAN) technology to support video, communication with non-extravehicular activity (EVA) assets such as wireless sensors and robotic assistants, and a redundant path for mission-critical EVA data. This paper recommends the replacement of the existing EMU antenna with a new antenna that maintains the performance characteristics of the current antenna but with lower weight and volume footprints. NASA has funded several firms to develop such an antenna over the past few years, and the most promising designs are variations on the basic patch antenna. This antenna technology at UHF is considered by the authors to be mature and ready for infusion into NASA AEMU technology development programs.

Design of broadband single polarized antenna

Science.gov (United States)

Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

2015-05-01

In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

Visualization of electromagnetic exposure near LTE antennae

Science.gov (United States)

Zvezdina, M. Yu; Shokova, Yu A.; Nazarova, O. Yu; Al-Ali, H. T. A.; Al-Farhan, G. H. A.

2018-01-01

Technical progress in wireless data transfer has given an opportunity to apply information and communication technologies in various areas of economics. Digital economy is linked to the 4th and 5th generation mobile network deployment. The peculiarities of the abovementioned standards decrease BTS antenna range three times in dense developed areas and worsen electromagnetic background in big cities. In the paper the comparative assessment results for rooftop electromagnetic exposure near BTS LTE and BTS GSM antennae are given. It is shown, that at the same level of transmitter power, energy flux density for LTE standard is three times less than the one for GSM. Moreover, the conclusion is made that the rooftop could be considered safe for people for indefinite time if antenna is placed more than 5 meters above the rooftop. The value of antenna height is taken to be on the safe side, as it is required by an application of “preventive principle”.

Modeling for control of an inflatable space reflector, the linear 1-D case

NARCIS (Netherlands)

Voß, T.; Scherpen, J.M.A.; van der Schaft, A.J.

2008-01-01

In this paper we develop a mathematical model of the dynamics for an inflatable space reflector, which can be used to design a controller for the shape of the inflatable structure. Inflatable structures have very nice properties, suitable for aerospace applications. We can construct e.g. a huge

Modeling for control of an inflatable space reflector, the nonlinear 1-D case

NARCIS (Netherlands)

Voß, T.; Scherpen, J.M.A.; Onck, P.R.

2008-01-01

In this paper we develop a mathematical model of the dynamics for an inflatable space reflector, which can be used to design a controller for the shape of the inflatable structure. Inflatable structures have very nice properties, suitable for aerospace applications. We can construct e.g. a huge

Non-uniformly sampled grids in double pole coordinate system for freeform reflector construction

Science.gov (United States)

Ma, Donglin; Pacheco, Shaun; Feng, Zexin; Liang, Rongguang

2015-08-01

We propose a new method to design freeform reflectors by nonuniformly sampling the source intensity distribution in double pole coordinate system. In double pole coordinate system, there is no pole for the whole hemisphere because both poles of the spherical coordinate system are moved to southernmost point of the sphere and overlapped together. With symmetric definition of both angular coordinates in the modified double pole coordinate system, a better match between the source intensity distribution and target irradiance distribution can be achieved for reflectors with large acceptance solid angle, leading to higher light efficiency and better uniformity on the target surface. With non-uniform sampling of the source intensity, we can design circular freeform reflector to obtain uniform rectangular illumination pattern. Aided by the feedback optimization, the freeform reflector can achieve the collection efficiency for ideal point source over 0.7 and relative standard deviation (RSD) less than 0.1.

Antenna Miniaturization with MEMS Tunable Capacitors

DEFF Research Database (Denmark)

Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

2014-01-01

In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss and their characterist......In today’s mobile device market, there is a strong need for efficient antenna miniaturization. Tunable antennas are a very promising way to reduce antenna volume while enlarging its operating bandwidth. MEMS tunable capacitors are state-ofthe- art in terms of insertion loss...

Resonant-bar gravitational radiation antennas

International Nuclear Information System (INIS)

Blair, D.G.

1987-01-01

This paper reviews the concept of gravitational radiation, and describes the worldwide research programme for the development of high-sensitivity resonant-bar antennas which are aimed at detecting gravitational radiation from astrophysical sources. (author)

Design and measured performances of a plane reflector augmented box-type solar-energy cooker

International Nuclear Information System (INIS)

Ekechukwu, O.V.

2001-06-01

The design philosophy, construction and measured performances of a plane-reflector augmented box-type solar-energy cooker are presented. The experimental solar cooker consists of an aluminum plate absorber painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator. The reflector consists of a wooden-framed commercially-available specular plane mirror which is sized to form a cover for the box when not in use. Provision is made for four cooking vessels each capable of holding up to 1 kg of water. Results of thermal performance tests show stagnation absorber plate temperatures of 138 deg. C and 119 deg. C for the cooker with and without the plane reflector in place, respectively. Boiling times of 60 minutes (3600 seconds) and 70 minutes (4200 seconds) for 1 kg of water, for the cooker with and without the reflector in place, respectively, were recorded. The solar cooker performance has been rated using the first figure of merit (F 1 ) on the no-load test and the second figure of merit (F 2 ) on the sensible heat tests. Predicted water boiling times using the two figures of merit compared favourable with measured values. The performance of the cooker with the plane reflector in place was improved tremendously compared to that without the reflector in place. (author)

The Millimeter Wave Observatory antenna now at INAOE-Mexico

Science.gov (United States)

Luna, A.

2017-07-01

The antenna of 5 meters in diameter of the legendary "Millimeter Wave Observatory" is now installed in the INAOE-Mexico. This historic antenna was reinstalled and was equipped with a control system and basic primary focus receivers that enabled it in teaching activities. We work on the characterization of its surface and on the development of receivers and spectrometers to allow it to do research Solar and astronomical masers. The historical contributions of this antenna to science and technology in radio astronomy, serve as the guiding force and the inspiration of the students and technicians of our postgrade in Astrophysics. It is enough to remember that it was with this antenna, that the first molecular outflow was discovered, several lines of molecular emission were discovered and it was the first antenna whose surface was characterized by holography; among many other technological and scientific contributions.

Phased array antenna control

Science.gov (United States)

Doland, G. D. (Inventor)

1978-01-01

Several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements are provided. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.

Electromagnetic reciprocity in antenna theory

CERN Document Server

Stumpf, Martin

2018-01-01

The reciprocity theorem is among the most intriguing concepts in wave field theory and has become an integral part of almost all standard textbooks on electromagnetic (EM) theory. This book makes use of the theorem to quantitatively describe EM interactions concerning general multiport antenna systems. It covers a general reciprocity-based description of antenna systems, their EM scattering properties, and further related aspects. Beginning with an introduction to the subject, Electromagnetic Reciprocity in Antenna Theory provides readers first with the basic prerequisites before offering coverage of the equivalent multiport circuit antenna representations, EM coupling between multiport antenna systems and their EM interactions with scatterers, accompanied with the corresponding EM compensation theorems.

Geodetic antenna calibration test in the Antarctic environment

Science.gov (United States)

Grejner-Brzezinska, A.; Vazquez, E.; Hothem, L.

2006-01-01

TransAntarctic Mountain DEFormation (TAMDEF) Monitoring Network is the NSF-sponsored OSU and USGS project, aimed at measuring crustal motion in the Transantarctic Mountains of Victoria Land using GPS carrier phase measurements. Station monumentation, antenna mounts, antenna types, and data processing strategies were optimized to achieve mm-level estimates for the rates of motion. These data contributes also to regional Antarctic frame definition. Significant amount of data collected over several years allow the investigation of unique aspects of GPS geodesy in Antarctica, to determine how the error spectrum compares to the mid-latitude regions, and to identify the optimum measurement and data processing schemes for Antarctic conditions, in order to test the predicted rates of motion (mm-level w.r.t. time). The data collection for the TAMDEF project was initiated in 1996. The primary antenna used has been the Ashtech L1/L2 Dorne Margolin (D/M) choke ring. A few occupations involved the use of a Trimble D/M choke ring. The data were processed using the antenna calibration data available from the National Geodetic Survey (NGS). The recent developments in new antenna designs that are lighter in weight and lower in cost are being considered as a possible alternative to the bulkier and more expensive D/M choke ring design. In November 2003, in situ testing of three alternative models of L1/L2 antennas was conducted at a site located in the vicinity of McMurdo Station, Antarctica (S77.87, E166.56). The antenna models used in this test were: Ashtech D/M choke ring, Trimble D/M choke ring, Trimble Zephyr, and the NovAtel GPS-702. Two stations, spaced within 30 meters, were used in the test. Both had the characteristics similar to the stations of the TAMDEF network, i.e., the UNAVCO fixed-height, force-centered level mounts with a constant antenna offset were used, ensuring extreme stability of the antenna/ mount/pin set up. During each of the four 3-day test data collection

Simulating the JET ITER-like Antenna circuit

International Nuclear Information System (INIS)

Van Eester, D.; Lerche, E.; Durodie, F.; Evrard, M.; Huygen, S.; Ongena, J.; Vrancken, M.; Argouarch, A.; Blackman, T.; Jacquet, P.; Mayoral, M.-L.; Monakhov, I.; Nightingale, M.; Wooldridge, E.; Whitehurst, A.; Goulding, R. H.

2009-01-01

A set of simulation/interpretation tools based on transmission line theory and on the RF model developed by M. Vrancken has been developed to study the ITER-like Antenna (ILA) at JET. For given tuning element settings, the unique solution of the equations governing the ILA circuit requires solving a system of coupled linear equations relating the voltages and currents at the antenna straps and other key locations. This computation allows cross-checking predicted values against measured experimental ones. Further more, a minimization procedure allows improving the correspondence with the quantities measured in the circuit during shots, thus coping with unavoidable errors arising from uncertainties in the measurements or from inaccuracies in the adopted RF model. Typical applications are e.g. fine-tuning of the second-stage of the ILA circuit for increased ELM-resilience, cross-checking the calibration of the measurements throughout the circuit and predicting the antenna performance and matching conditions in new plasma scenarios.

The upgrade of intense pulsed neutron source (IPNS) through the change of coolant and reflector

CERN Document Server

Baek, I C; Iverson, E B

2002-01-01

The current intense pulsed neutron source (IPNS) depleted uranium target is cooled by light water. The inner reflector material is graphite and the outer reflector material is beryllium. The presence of H sub 2 O in the target moderates neutrons and leads to a higher absorption loss in the target than is necessary. D sub 2 O coolant in the small quantities required minimizes this effect. We have studied the possible improvement in IPNS beam fluxes that would result from changing the coolant from H sub 2 O to D sub 2 O and the inner reflector from graphite to beryllium. Neutron intensities were calculated for directions normal to the viewed surface of each moderator for four different cases of combinations of target coolant and reflector materials. The simulations reported here were performed using the MCNPX (version 2.1.5) computer program. Our results show that substantial gains in neutron beam intensities can be achieved by appropriate combination of target coolant and reflector materials. The combination o...

DEVELOPMENT OF CONCEPT OF HARDWARE-SOFTWARE COMPLEX OF MODULAR DESIGN FOR DETERMINATION OF ANTENNA SYSTEMS׳ CHARACTERISTICS BASED ON MEASUREMENTS IN THE NEAR FIELD

Directory of Open Access Journals (Sweden)

A. G. Buday

2017-01-01

Full Text Available Measuring the amplitude-phase distribution of the radiation field of complex antenna systems on a certain surface close to the radiating aperture allows solving the problem of reconstructing the free-space diagram in the far field and also helps in determining the influence of various structural elements and defects of radiating surfaces on formation of directional diagram. The purpose of this work was to develop a universal hardware-software complex of a modular design aimed for determining the characteristics of wide range of antenna systems in respect of measurements of the amplitude-phase distribution of the radiation field in the near zone.The equations that connect the structure of radiation fields of the antenna system at various distances from it in planar, cylindrical and spherical coordinate systems as well as structural diagrams of the hardware part of measuring complexes have been analyzed.As a result, the concept of constructing a universal hardware-software complex for measuring the radiation field of various types of antenna systems with any type of measurement surface for solving a wide range of applied problems has been developed. A modular structure of hardware and software has been proposed; it allows reconfiguring the complex rapidly in order to measure the characteristics of any particular antenna system at all stages of product development and testing, and also makes the complex economically accessible even for small enterprises and organizations.

Novel method to control antenna currents based on theory of characteristic modes

Science.gov (United States)

Elghannai, Ezdeen Ahmed

Characteristic Mode Theory is one of the very few numerical methods that provide a great deal of physical insight because it allows us to determine the natural modes of the radiating structure. The key feature of these modes is that the total induced antenna current, input impedance/admittance and radiation pattern can be expressed as a linear weighted combination of individual modes. Using this decomposition method, it is possible to study the behavior of the individual modes, understand them and therefore control the antennas behavior; in other words, control the currents induced on the antenna structure. This dissertation advances the topic of antenna design by carefully controlling the antenna currents over the desired frequency band to achieve the desired performance specifications for a set of constraints. Here, a systematic method based on the Theory of Characteristic Modes (CM) and lumped reactive loading to achieve the goal of current control is developed. The lumped reactive loads are determined based on the desired behavior of the antenna currents. This technique can also be used to impedance match the antenna to the source/generator connected to it. The technique is much more general than the traditional impedance matching. Generally, the reactive loads that properly control the currents exhibit a combination of Foster and non-Foster behavior. The former can be implemented with lumped passive reactive components, while the latter can be implemented with lumped non-Foster circuits (NFC). The concept of current control is applied to design antennas with a wide band (impedance/pattern) behavior using reactive loads. We successfully applied this novel technique to design multi band and wide band antennas for wireless applications. The technique was developed to match the antenna to resistive and/or complex source impedance and control the radiation pattern at these frequency bands, considering size and volume constraints. A wide band patch antenna was

The principles of radio engineering and antennas. II Antennas (2nd revised and enlarged edition)

Science.gov (United States)

Belotserkovskii, G. B.

This book represents the second part of a textbook for technical schools. The characteristics and parameters of antennas are considered along with transmission lines, the theory of single dipoles and radiator systems, and the technological realization of elements and units of the antenna-feeder system, taking into account filters and multiport networks for microwave communications applications, and ferrite circulators and isolators. The first edition of this textbook was published in 1969. For the current edition, the material in the first edition has been revised, and new material has been introduced. Much attention is given to microwave antennas, including, in particular, arrays with electrical scanning characteristics. Other topics discussed are related to the general principles of antennas, the matching of the impedance of transmission lines, the elements of transmission lines, aperture-type antennas for microwaves, and the functional characteristics of antennas for ultrashort waves.

Nanometers to centimeters: novel optical nano-antennas, with an eye to scaled production

Science.gov (United States)

James, Timothy D.; Cadusch, Jasper J.; Earl, Stuart K.; Panchenko, Evgeniy; Mulvaney, Paul; Davis, Timothy J.; Roberts, Ann

2016-03-01

Optical nano-antennas have been the focus of intense research recently due to their ability to manipulate electromagnetic radiation on a subwavelength scale, and there is major interest in such devices for a wide variety of applications in photonics, sensing, and imaging. Significant effort has been put into developing highly compact, novel, next-generation light sources, which have great potential in realizing efficient sub-wavelength single photon sources and enhanced biological and chemical sensors. We have developed a number of innovative optical antenna designs including elements of chiral metasurfaces for enabling circularly polarized emission from quantum sources, new designs derived from Radio Frequency (RF) elements for quantum source enhancement and directionality, and nanostructures for investigating plasmonic dark-modes that have the ability to significantly reduce the Q-factor of nano-antennas. A challenge, however, remains the development of a scalable nanofabrication technology. The capacity to mass-produce nano-antennas will have a considerable impact on the commercial viability of these devices, and greatly improve research throughput. Here we present recent progress in the development of scalable fabrication strategies for producing of nano-antennas and antenna arrays, along with slot based plasmonic optical devices.

Measuring device for bending of beryllium reflector

International Nuclear Information System (INIS)

Nishida, Seiri; Sakamoto, Naoki.

1994-01-01

The device of the present invention can measure bending of a beryllium reflector formed in a reactor core of a nuclear reactor by a relatively easy operation. Namely, a sensor portion comprises a long-support that can be inserted to a fuel element-insertion hole disposed in the reactor and a plurality of distance sensors disposed in a longitudinal direction of the support. A supersonic wave sensor which is advantageous in the heat resistance, the size and the accuracy and can conduct measurement in water relatively easily is used as the distance sensors. However, other sensors, instead of the sensor described above, may also be used. The plurality of distance sensors detect the bending amount of the beryllium reflector in the longitudinal direction by such an easy operation of inserting such a sensor portion to the fuel element-insertion hole upon exchange of fuel elements. (I.S.)

Multiple Antenna Systems with Inherently Decoupled Radiators

DEFF Research Database (Denmark)

Pelosi, Mauro; Knudsen, Mikael B.; Pedersen, Gert Frølund

2012-01-01

In multiple antenna systems mutual coupling needs to be minimized. We propose an alternative novel decoupling technique, investigating several multiple antenna configurations for small handsets through measurements and numerical simulations. The influence of different novel designs on performance...... metrics such as total loss, antenna isolation and envelope correlation coefficient are investigated. By varying antenna impedance bandwidth and antenna location with respect to the handset, both Planar Inverted F Antenna (PIFA) and Inverted F Antennas (IFA) were investigated in different UMTS frequency...

REVIEW ARTICLE: Bioluminescent signals and the role of reflectors

Science.gov (United States)

Herring, Peter J.

2000-11-01

Organisms in a well lit environment use optical signals derived from the selective reflection of ambient light. In a dim or dark environment it is very difficult (because of low photon numbers) to detect the contrast between light reflected from the organism and that from the background, and many organisms use bioluminescent signals instead. The use of such signals on land is largely restricted to sexual signalling by the luminous beetles, but in the deep ocean their use is widespread, involving both many different organisms and a range of uses which parallel those of reflective signals on land. Some bioluminescent signals rely almost entirely on an optically unmodified light source (e.g. a secretion) but others depend upon complex optical structures, particularly reflectors, in the light-emitting organs. Reflectors in the light organs of many shrimp, squid and fish are based on constructive interference systems but employ different biological materials. They and other structures modify the angular, spectral and intensity distributions of bioluminescent signals. The ready availability of highly efficient biological reflectors has been a formative influence in the evolution of bioluminescent signalling in the sea.

Wireless interrogation of passive antenna sensors

International Nuclear Information System (INIS)

Deshmukh, S; Huang, H

2010-01-01

Recently, we discovered that the resonant frequency of a microstrip patch antenna is sensitive to mechanical strains or crack presence in the ground plane. Based on this principle, antenna sensors have been demonstrated to measure strain and detect crack in metallic structures. This paper presents a wireless method to remotely interrogate a dual-frequency antenna sensor. An interrogation horn antenna was used to irradiate the antenna sensor with a linear chirp microwave signal. By implementing a light-activated switch at the sensor node and performing signal processing of the backscattered signals, the resonant frequencies of the antenna sensor along both polarizations can be measured remotely. Since the antenna sensor does not need a local power source and can be interrogated wirelessly, electric wiring can be eliminated. The sensor implementation, the signal processing and the experimental setup that validate the remote interrogation of the antenna sensor are presented. A power budget model has also been established to estimate the maximum interrogation range

Stretchable antenna for wearable electronics

KAUST Repository

Hussain, Muhammad Mustafa

2017-04-13

Various examples are provided for stretchable antennas that can be used for applications such as wearable electronics. In one example, a stretchable antenna includes a flexible support structure including a lateral spring section having a proximal end and at a distal end; a metallic antenna disposed on at least a portion of the lateral spring section, the metallic antenna extending along the lateral spring section from the proximal end; and a metallic feed coupled to the metallic antenna at the proximal end of the lateral spring section. In another example, a method includes patterning a polymer layer disposed on a substrate to define a lateral spring section; disposing a metal layer on at least a portion of the lateral spring section, the metal layer forming an antenna extending along the portion of the lateral spring section; and releasing the polymer layer and the metal layer from the substrate.

A Compact UWB Diversity Antenna

Directory of Open Access Journals (Sweden)

Hui Zhao

2014-01-01

Full Text Available A compact printed ultrawideband (UWB diversity antenna with a size of 30 mm × 36 mm operating at a frequency range of 3.1–10.6 GHz is proposed. The antenna is composed of two semielliptical monopoles fed by two microstrip lines. Two semicircular slots, two rectangular slots, and one stub are introduced in the ground plane to adjust the impedance bandwidth of the antenna and improve the isolation between two feeding ports. The simulated and measured results show that impedance bandwidth of the proposed antenna can cover the whole UWB band with a good isolation of < −15 dB. The radiation patterns, peak antenna gain, and envelope correlation coefficient are also measured and discussed. The measured results show that the proposed antenna can be a good candidate for some portable MIMO/diversity UWB applications.

Flexible, angle-independent, structural color reflectors inspired by morpho butterfly wings.

Science.gov (United States)

Chung, Kyungjae; Yu, Sunkyu; Heo, Chul-Joon; Shim, Jae Won; Yang, Seung-Man; Han, Moon Gyu; Lee, Hong-Seok; Jin, Yongwan; Lee, Sang Yoon; Park, Namkyoo; Shin, Jung H

2012-05-08

Thin-film color reflectors inspired by Morpho butterflies are fabricated. Using a combination of directional deposition, silica microspheres with a wide size distribution, and a PDMS (polydimethylsiloxane) encasing, a large, flexible reflector is created that actually provides better angle-independent color characteristics than Morpho butterflies and which can even be bent and folded freely without losing its Morpho-mimetic photonic properties. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A combination of transformation optics and surface impedance modulation to design compact retrodirective reflectors

Directory of Open Access Journals (Sweden)

H. Haddad

2018-02-01

Full Text Available This study proposes a new approach to flatten retrodirective corner reflectors. The proposed method enables compact reflectors via Transformation Optics (TO combined with Surface Impedance Modulation (SIM. This combination permits to relax the constraints on the anisotropic material resulting from the TO. Phase gradient approach is generalized to be used within anisotropic media and is implemented with SIM. Different reflector setups are designed, simulated and compared for fop = 8GHz using ANSYS® HFSS® in order to validate the use of such a combination.

The development of the miniaturized waveform receiver with the function measuring Antenna Impedance in space plasmas

Science.gov (United States)

Ishii, H.; Kojima, H.; Fukuhara, H.; Okada, S.; Yamakawa, H.

2012-04-01

Plasma wave is one of the most essential physical quantities in the solar terrestrial physics. The role of plasma wave receiver onboard satellites is to detect plasma waves in space with a good signal to noise ratio. There are two types of plasma wave receivers, the sweep frequency analyzer and the waveform capture. While the sweep frequency analyzer provides plasma wave spectra, the waveform capture obtains waveforms with phase information that is significant in studying nonlinear phenomena. Antenna sensors to observe electric fields of the plasma waves show different features in plasmas from in vacuum. The antenna impedances have specific characteristics in the frequency domain because of the dispersion of plasmas. These antenna impedances are expressed with complex number. We need to know not only the antenna impedances but also the transfer functions of plasma wave receiver's circuits in order to calibrate observed waveforms precisely. The impedances of the electric field antennas are affected by a state of surrounding plasmas. Since satellites run through various regions with different plasma parameters, we precisely should measure the antenna impedances onboard spacecraft. On the contrary, we can obtain the plasma density and by measuring the antenna impedances. Several formulas of the antenna impedance measurement system were proposed. A synchronous detection method is used on the BepiColombo Mercury Magnetospheric Orbiter (MMO), which will be launched in 2014. The digital data are stored in the onboard memory. They are read out and converted to the analog waveforms by D/A converter. They are fed into the input of the preamplifiers of antenna sensors through a resistor. We can calculate a transfer function of the circuit by applying the synchronous detection method to the output waveform from waveform receivers and digital data as a signal source. The size of this system is same as an A5 board. In recent years, Application Specific Integrated Circuit (ASIC

Radiation and scattering from cylindrically conformal printed antennas. Ph.D. Thesis Final Report

Science.gov (United States)

Kempel, Leo C.; Volakis, John L.

1994-01-01

Microstrip patch antennas offer considerable advantages in terms of weight, aerodynamic drag, cost, flexibility, and observables over more conventional protruding antennas. These flat patch antennas were first proposed over thirty years ago by Deschamps in the United States and Gutton and Baisinot in France. Such antennas have been analyzed and developed for planar as well as curved platforms. However, the methods used in these designs employ gross approximations, suffer from extreme computational burden, or require expensive physical experiments. The goal of this thesis is to develop accurate and efficient numerical modeling techniques which represent actual antenna structures mounted on curved surfaces with a high degree of fidelity. In this thesis, the finite element method is extended to cavity-backed conformal antenna arrays embedded in a circular, metallic, infinite cylinder. Both the boundary integral and absorbing boundary mesh closure conditions will be used for terminating the mesh. These two approaches will be contrasted and used to study the scattering and radiation behavior of several useful antenna configurations. An important feature of this study will be to examine the effect of curvature and cavity size on the scattering and radiation properties of wraparound conformal antenna arrays.

47 CFR 73.510 - Antenna systems.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.510 Section 73.510... Noncommercial Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial educational... § 73.316 concerning antenna systems contained in subpart B of this part. (b) Directional antenna. No...

DEA deformed stretchable patch antenna

International Nuclear Information System (INIS)

Jiang, X-J; Jalali Mazlouman, S; Menon, C; Mahanfar, A; Vaughan, R G

2012-01-01

A stretchable patch antenna (SPA) whose frequency is tuned by a planar dielectric elastomer actuator (DEA) is presented in this paper. This mechanically reconfigurable antenna system has a configuration resembling a pre-stretched silicone belt. Part of the belt is embedded with a layer of conductive liquid metal to form the patch antenna. Part of the belt is sandwiched between conductive electrodes to form the DEA. Electrical activation of the DEA results in a contraction of the patch antenna, and as a result, in a variation of its resonance frequency. Design and fabrication steps of this system are presented. Measurement results for deformation, resonance frequency variation and efficiency of the patch antenna are also presented. (paper)

The ICRF antennas for TFTR

International Nuclear Information System (INIS)

Hoffman, D.J.; Colestock, P.L.; Gardner, W.L.; Hosea, J.C.; Nagy, A.; Stevens, J.; Swain, D.W.; Wilson, J.R.

1988-01-01

Two compact loop antennas have been designed to provide ion cyclotron resonant frequency (ICRF) heating for TFTR. The antennas can convey a total of 10 MW to accomplish core heating in either high-density or high-temperature plasmas. The near-term goal of heating TFTR plasmas and the longer-term goals of ease in handling (for remote maintenance) and high reliability (in an inaccessible tritium tokamak environment) were major considerations in the antenna designs. The compact loop configuration facilitates handling because the antennas fit completely through their ports. Conservative design and extensive testing were used to attain the reliability required for TFTR. This paper summarizes how these antennas will accomplish these goals. 5 figs, 1 tab