Observation of solar radio bursts using swept-frequency radiospectrograph in 20 - 40 MHz band

International Nuclear Information System (INIS)

Aoyama, Takashi; Oya, Hiroshi.

1987-01-01

A new station for the observation of solar decametric radio bursts has been developed at Miyagi Vocational Training College in Tsukidate, Miyagi, Japan. Using the swept frequency radiospectrograph covering a frequency range from 20 MHz to 40 MHz within 200 msec, with bandwidth of 30 kHz, the radio outbursts from the sun have been currently monitored with colored dynamic spectrum display. After July 1982, successful observations provide the data which include all types of solar radio bursts such as type I, II, III, IV and V in the decametric wavelength range. In addition to these typical radio bursts, rising tone bursts with fast drift rate followed by strong type III bursts and a series of bursts repeating rising and falling tone bursts with slow drift rate have been observed. (author)

Ka-band to L-band frequency down-conversion based on III-V-on-silicon photonic integrated circuits

Science.gov (United States)

Van Gasse, K.; Wang, Z.; Uvin, S.; De Deckere, B.; Mariën, J.; Thomassen, L.; Roelkens, G.

2017-12-01

In this work, we present the design, simulation and characterization of a frequency down-converter based on III-V-on-silicon photonic integrated circuit technology. We first demonstrate the concept using commercial discrete components, after which we demonstrate frequency conversion using an integrated mode-locked laser and integrated modulator. In our experiments, five channels in the Ka-band (27.5-30 GHz) with 500 MHz bandwidth are down-converted to the L-band (1.5 GHz). The breadboard demonstration shows a conversion efficiency of - 20 dB and a flat response over the 500 MHz bandwidth. The simulation of a fully integrated circuit indicates that a positive conversion gain can be obtained on a millimeter-sized photonic integrated circuit.

The Low Band Observatory (LOBO): Expanding the VLA Low Frequency Commensal System for Continuous, Broad-band, sub-GHz Observations

Science.gov (United States)

Kassim, Namir E.; Clarke, Tracy E.; Helmboldt, Joseph F.; Peters, Wendy M.; Brisken, Walter; Hyman, Scott D.; Polisensky, Emil; Hicks, Brian

2015-01-01

The Naval Research Laboratory (NRL) and the National Radio Astronomy Observatory (NRAO) are currently commissioning the VLA Low Frequency Ionosphere and Transient Experiment (VLITE) on a subset of JVLA antennas at modest bandwidth. Its bounded scientific goals are to leverage thousands of JVLA on-sky hours per year for ionospheric and transient studies, and to demonstrate the practicality of a prime-focus commensal system on the JVLA. Here we explore the natural expansion of VLITE to a full-antenna, full-bandwidth Low Band Observatory (LOBO) that would follow naturally from a successful VLITE experience. The new Low Band JVLA receivers, coupled with the existing primary focus feeds, can access two frequency bands: 4 band (54 - 86 MHz) and P band (236-492 MHz). The 4 band feeds are newly designed and now undergoing testing. If they prove successful then they can be permanently mounted at the primary focus, unlike their narrow band predecessors. The combination of Low Band receivers and fixed, primary-focus feeds could provide continuous, broad-band data over two complimentary low-frequency bands. The system would also leverage the relatively large fields-of-view of ~10 degrees at 4 band, and ~2.5 degrees at P band, coupling an excellent survey capability with a natural advantage for serendipitous discoveries. We discuss the compelling science case that flows from LOBO's robust imaging and time domain capabilities coupled with thousands of hours of wide-field, JVLA observing time each year. We also touch on the possibility to incorporate Long Wavelength Array (LWA) stations as additional 'dishes' through the LOBO backend, to improve calibration and sensitivity in LOBO's 4 band.

47 CFR 101.82 - Reimbursement and relocation expenses in the 2110-2150 MHz and 2160-2200 MHz bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Reimbursement and relocation expenses in the... License Transfers, Modifications, Conditions and Forfeitures § 101.82 Reimbursement and relocation expenses in the 2110-2150 MHz and 2160-2200 MHz bands. (a) Reimbursement and relocation expenses for the...

A Novel Dual-Band Rectenna for Ambient RF Energy Harvesting at GSM 900 MHz and 1800 MHz

Directory of Open Access Journals (Sweden)

Dinh Khanh Ho

2017-06-01

Full Text Available This paper presents a novel dual-band rectenna for RF energy harvesting system. This rectenna is created from a dual-band antenna and a dual-band rectifier which operates at GSM bands (900 MHz and 1800 MHz. The printed monopole antenna is miniaturized by two meander-lines. The received signal from the receiving antenna is rectified by a voltage double using Schottky diode SMS-7630. The rectifier is optimized for low input power level of -20dBm using harmonic balance. Prototype is designed and fabricated. The simulation is validated by measurement with power conversion efficiency of 20% and 40.8% (in measurement at the input power level of -20dBm. The proposed rectenna has output voltage from 183-415 mV. From the measured results, this rectenna provides the possibility to harvest the ambient electromagnetic energy for powering low-power electronic devices.

Sharing the 620-790 MHz band allocated to terrestrial television with an audio-bandwidth social service satellite system

Science.gov (United States)

Smith, E. K.; Reinhart, E. E.

1977-01-01

A study was carried out to identify the optimum uplink and downlink frequencies for audio-bandwidth channels for use by a satellite system distributing social services. The study considered functional-user-need models for five types of social services and identified a general baseline system that is appropriate for most of them. Technical aspects and costs of this system and of the frequency bands that it might use were reviewed, leading to the identification of the 620-790 MHz band as a perferred candidate for both uplink and downlink transmissions for nonmobile applications. The study also led to some ideas as to how to configure the satellite system.

76 FR 51271 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

Science.gov (United States)

2011-08-18

... 700 MHz Band AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this document... medical services, Incorporation by reference, Individuals with disabilities, Radio, Reporting and...- 798 MHz bands. * * * * * Service Availability. The use of a public safety broadband network on a day...

MEMS Tunable Antennas to Address LTE 600 MHz-bands

DEFF Research Database (Denmark)

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

2015-01-01

The broadcast television spectrum around 600 MHz has been freed in the united states and will be put for auction to wireless carriers in 2015. The newest generation of mobile communication standards will be deployed on these newly available bands, to provide mobile device users with an enhanced c...

Circularly Polarized S Band Dual Frequency Square Patch Antenna Using Glass Microfiber Reinforced PTFE Composite

Directory of Open Access Journals (Sweden)

M. Samsuzzaman

2014-01-01

Full Text Available Circularly polarized (CP dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the desired operating band. The experimental results show that the impedance bandwidth is approximately 30 MHz (2.16 GHz to 2.19 GHz for lower band and 40 MHz (3.29 GHz to 3.33 GHz for higher band with an average peak gain of 6.59 dBiC and 5.52 dBiC, respectively. Several optimizations are performed to obtain the values of the antenna physical parameters. Moreover, the proposed antenna possesses compactness, light weight, simplicity, low cost, and circularly polarized. It is an attractive candidate for dual band satellite antennas where lower band can be used for uplink and upper band can be used for downlink.

76 FR 62309 - Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band

Science.gov (United States)

2011-10-07

... the 700 MHz Band AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: In this... spectrum of the 700 MHz band. The Commission dismissed the request, but clarified that a reasonably broad... personnel including, but not limited to, activities of police, fire and medical emergency first responders...

Microwave frequency detector at X-band using GaAs MMIC technology

International Nuclear Information System (INIS)

Zhang Jun; Liao Xiaoping; Jiao Yongchang

2009-01-01

The design, fabrication, and experimental results of an MEMS microwave frequency detector are presented for the first time. The structure consists of a microwave power divider, two CPW transmission lines, a microwave power combiner, an MEMS capacitive power sensor and a thermopile. The detector has been designed and fabricated on GaAs substrate using the MMIC process at the X-band successfully. The MEMS capacitive power sensor is used for detecting the high power signal, while the thermopile is used for detecting the low power signal. Signals of 17 and 10 dBm are measured over the X-band. The sensitivity is 0.56 MHz/fF under 17 dBm by the capacitive power sensor, and 6.67 MHz/μV under 10 dBm by the thermopile, respectively. The validity of the presented design has been confirmed by the experiment.

47 CFR 90.355 - LMS operations below 512 MHz.

Science.gov (United States)

2010-10-01

... PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.355 LMS... LMS station and the nearest co-channel base station of another licensee operating a voice system is 75... MHz, 150-170 MHz, and 450-512 MHz bands may use either base-mobile frequencies currently assigned the...

Searching for MHz Transients with the VLA Low-band Ionosphere and Transient Experiment (VLITE)

Science.gov (United States)

Polisensky, Emil; Peters, Wendy; Giacintucci, Simona; Clarke, Tracy; Kassim, Namir E.; hyman, Scott D.; van der Horst, Alexander; Linford, Justin; Waldron, Zach; Frail, Dale

2018-01-01

NRL and NRAO have expanded the low frequency capabilities of the VLA through the VLA Low-band Ionosphere and Transient Experiment (VLITE, http://vlite.nrao.edu/ ), effectively making the instrument two telescopes in one. VLITE is a commensal observing system that harvests data from the prime focus in parallel with normal Cassegrain focus observing on a subset of VLA antennas. VLITE provides over 6000 observing hours per year in a > 5 square degree field-of-view using 64 MHz bandwidth centered on 352 MHz. By operating in parallel, VLITE offers invaluable low frequency data to targeted observations of transient sources detected at higher frequencies. With arcsec resolution and mJy sensitivity, VLITE additionally offers great potential for blind searches of rarer radio-selected transients. We use catalog matching software on the imaging products from the daily astrophysics pipeline and the LOFAR Transients Pipeline (TraP) on repeated observations of the same fields to search for coherent and incoherent astronomical transients on timescales of a few seconds to years. We present the current status of the VLITE transient science program from its initial deployment on 10 antennas in November 2014 through its expansion to 16 antennas in the summer of 2017. Transient limits from VLITE’s first year of operation (Polisensky et al. 2016) are updated per the most recent analysis.

Design of dual band FSS by using quadruple L-slot technique

Science.gov (United States)

Fauzi, Noor Azamiah Md; Aziz, Mohamad Zoinol Abidin Abd.; Said, Maizatul Alice Meor; Othman, Mohd Azlishah; Ahmad, Badrul Hisham; Malek, Mohd Fareq Abd

2015-05-01

This paper presents a new design of dual band frequency selective surface (FSS) for band pass microwave transmission application. FSS can be used on energy saving glass to improve the transmission of wireless communication signals through the glass. The microwave signal will be attenuate when propagate throughout the different structure such as building. Therefore, some of the wireless communication system cannot be used in the optimum performance. The aim of this paper is designed, simulated and analyzed the new dual band FSS structure for microwave transmission. This design is based on a quadruple L slot combined with cross slot to produce pass band at 900 MHz and 2.4 GHz. The vertical of pair inverse L slot is used as the band pass for the frequency of 2.4GHz. While, the horizontal of pair inverse L slot is used as the band pass at frequency 900MHz. This design is simulated and analyzed by using Computer Simulation Technology (CST) Microwave Studio (MWS) software. The characteristics of the transmission (S21) and reflection (S11) of the dual band FSS were simulater and analyzed. The bandwidth of the first band is 118.91MHz which covered the frequency range from 833.4MHz until 952.31MHz. Meanwhile, the bandwidth for the second band is 358.84MHz which covered the frequency range from 2.1475GHz until 2.5063GHz. The resonance/center frequency of this design is obtained at 900MHz with a 26.902dB return loss and 2.37GHz with 28.506dB a return loss. This FSS is suitable as microwave filter for GSM900 and WLAN 2.4GHz application.

47 CFR 95.1119 - Specific requirements for wireless medical telemetry devices operating in the 608-614 MHz band.

Science.gov (United States)

2010-10-01

... devices operating in the 608-614 MHz band. For a wireless medical telemetry device operating within the... 47 Telecommunication 5 2010-10-01 2010-10-01 false Specific requirements for wireless medical telemetry devices operating in the 608-614 MHz band. 95.1119 Section 95.1119 Telecommunication FEDERAL...

47 CFR 87.475 - Frequencies.

Science.gov (United States)

2010-10-01

... with simultaneous radiotelephone channels and their associated glide path station frequency from the...) VHF omni-range (VOR) stations are to be assigned frequencies in the 112.050-117.950 MHz band (50 kHz channel spacing) and the following frequencies in the 108-112 MHz band: 108.200 108.250 108.400 108.450...

Evaluation of SAR in a human body model due to wireless power transmission in the 10 MHz band.

Science.gov (United States)

Laakso, Ilkka; Tsuchida, Shogo; Hirata, Akimasa; Kamimura, Yoshitsugu

2012-08-07

This study discusses a computational method for calculating the specific absorption rate (SAR) due to a wireless power transmission system in the 10 MHz frequency band. A two-step quasi-static method comprised of the method of moments and the scalar potential finite-difference method are proposed. The applicability of the quasi-static approximation for localized exposure in this frequency band is discussed by comparing the SAR in a lossy dielectric cylinder computed with a full-wave electromagnetic analysis and the quasi-static approximation. From the computational results, the input impedance of the resonant coils was affected by the existence of the cylinder. On the other hand, the magnetic field distribution in free space and considering the cylinder and an impedance matching circuit were in good agreement; the maximum difference in the amplitude of the magnetic field was 4.8%. For a cylinder-coil distance of 10 mm, the difference between the peak 10 g averaged SAR in the cylinder computed with the full-wave electromagnetic method and our quasi-static method was 7.8%. These results suggest that the quasi-static approach is applicable for conducting the dosimetry of wireless power transmission in the 10 MHz band. With our two-step quasi-static method, the SAR in the anatomically based model was computed for different exposure scenarios. From those computations, the allowable input power satisfying the limit of a peak 10 g averaged SAR of 2.0 W kg(-1) was 830 W in the worst case exposure scenario with a coil positioned at a distance of 30 mm from the chest.

Development of a new concept automatic frequency controller for an ultrasmall C-band linear accelerator guide

International Nuclear Information System (INIS)

Kamino, Yuichiro; Tsukuda, Kazuhiro; Kokubo, Masaki; Miura, Sadao; Hirai, Etsuro; Hiraoka, Masahiro; Ishikawa, Junzo

2007-01-01

We are developing a four-dimensional, image-guided radiotherapy system with a gimbaled x-ray head. The system has pursuing irradiation capability in addition to precise irradiation capability, owing to its agile x-ray head. The moving x-ray head requires a very small C-band accelerator guide. The heat intensity of the accelerator guide is much higher than that of conventional S-band medical linear accelerators. The resonance frequency varies over almost 1.0 MHz with a thermal time constant of about 30 s. An automatic frequency controller (AFC) is employed to compensate for this variation in resonance frequency. Furthermore, we noted that fast AFC response is important for step-and-shoot intensity modulation radiotherapy (IMRT), in which the beam is turned on and off frequently. Therefore, we invented a digital AFC, based on a new concept, to provide effective compensation for the thermal characteristics of the accelerator guide and to ensure stable and optimized x-ray treatment. An important aspect of the performance of the AFC is the capture-frequency range over which the AFC can seek, lock on to, and track the resonance frequency. The conventional, analog AFC used in S-band medical linear accelerators would have a capture-frequency range of about 0.9 MHz, if applied to our accelerator guide, and would be inappropriate. Conversely, our new AFC has a capture-frequency range of 24 MHz, which is well suited to our accelerator guide. The design concept behind this new AFC has been developed and verified. A full prototype system was constructed and tested on an existing accelerator guide at the rated x-ray output (500 cGy/min) of our radiotherapy system, with a pulse-repetition frequency of 300 Hz. The AFC acquired the resonance frequency of the accelerator guide within 0.15 s after beam-on, and provided stable tracking and adjustment of the frequency of the microwave source to the resonance frequency of the accelerator guide. With a planned improvement of the

ISM band to U-NII band frequency transverter and method of frequency transversion

Science.gov (United States)

Stepp, Jeffrey David [Grandview, MO; Hensley, Dale [Grandview, MO

2006-09-12

A frequency transverter (10) and method for enabling bi-frequency dual-directional transfer of digitally encoded data on an RF carrier by translating between a crowded or otherwise undesirable first frequency band, such as the 2.4 GHz ISM band, and a less-crowded or otherwise desirable second frequency band, such as the 5.0 GHz 6.0 GHz U-NII band. In a preferred embodiment, the transverter (10) connects between an existing data radio (11) and its existing antenna (30), and comprises a bandswitch (12); an input RF isolating device (14); a transmuter (16); a converter (18); a dual output local oscillator (20); an output RF isolating device (22); and an antenna (24) tuned to the second frequency band. The bandswitch (12) allows for bypassing the transverter (10), thereby facilitating its use with legacy systems. The transmuter (14) and converter (16) are adapted to convert to and from, respectively, the second frequency band.

GHz band frequency hopping PLL-based frequency synthesizers

Institute of Scientific and Technical Information of China (English)

XU Yong; WANG Zhi-gong; GUAN Yu; XU Zhi-jun; QIAO Lu-feng

2005-01-01

In this paper we describe a full-integrated circuit containing all building blocks of a completed PLL-based synthesizer except for low pass filter(LPF).The frequency synthesizer is designed for a frequency hopping (FH) transceiver operating up to 1.5 GHz as a local oscillator. The architecture of Voltage Controlled Oscillator (VCO) is optimized to get better performance, and a phase noise of -111.85-dBc/Hz @ 1 MHz and a tuning range of 250 MHz are gained at a centre frequency of 1.35 GHz.A novel Dual-Modulus Prescaler(DMP) is designed to achieve a very low jitter and a lower power.The settling time of PLL is 80 μs while the reference frequency is 400 KHz.This monolithic frequency synthesizer is to integrate all main building blocks of PLL except for the low pass filter,with a maximum VCO output frequency of 1.5 GHz,and is fabricated with a 0.18 μm mixed signal CMOS process. Low power dissipation, low phase noise, large tuning range and fast settling time are gained in this design.

Evaluation of SAR in a human body model due to wireless power transmission in the 10 MHz band

International Nuclear Information System (INIS)

Laakso, Ilkka; Tsuchida, Shogo; Hirata, Akimasa; Kamimura, Yoshitsugu

2012-01-01

This study discusses a computational method for calculating the specific absorption rate (SAR) due to a wireless power transmission system in the 10 MHz frequency band. A two-step quasi-static method comprised of the method of moments and the scalar potential finite-difference method are proposed. The applicability of the quasi-static approximation for localized exposure in this frequency band is discussed by comparing the SAR in a lossy dielectric cylinder computed with a full-wave electromagnetic analysis and the quasi-static approximation. From the computational results, the input impedance of the resonant coils was affected by the existence of the cylinder. On the other hand, the magnetic field distribution in free space and considering the cylinder and an impedance matching circuit were in good agreement; the maximum difference in the amplitude of the magnetic field was 4.8%. For a cylinder–coil distance of 10 mm, the difference between the peak 10 g averaged SAR in the cylinder computed with the full-wave electromagnetic method and our quasi-static method was 7.8%. These results suggest that the quasi-static approach is applicable for conducting the dosimetry of wireless power transmission in the 10 MHz band. With our two-step quasi-static method, the SAR in the anatomically based model was computed for different exposure scenarios. From those computations, the allowable input power satisfying the limit of a peak 10 g averaged SAR of 2.0 W kg −1 was 830 W in the worst case exposure scenario with a coil positioned at a distance of 30 mm from the chest. (paper)

Evaluation Of Electromagnetic Fields For Frequencies 900 MHz-1 800 MHz In Tirana

Directory of Open Access Journals (Sweden)

Kuqi Dhurata

2015-07-01

Full Text Available Abstract The massive use of mobile phone as a communication tool nowadays is accompanied the ever increasing interest of the public and researchers for the possibly impact on human health as a result of exposure to the electromagnetic fields that accompany these devices. Therefore knowing the level of exposure electromagnetic fields of this electronic equipment has been and will be in the future interest object to the public and the subject of study for the researchers. In this paper are presents the results of measurements of electromagnetic fields for the frequencies 900 MHz - 1800 MHz used in mobile telephone in Tirana. These frequencies are included in the area radio frequency RF and Microwave MW 300 Hz - 300 GHz in the spectrum of electromagnetic waves and belong to non-ionizing radiation. The measurements were performed in different areas of Tirana. The purpose is to assess the level of exposure electromagnetic fields especially near areas where mobile antennas are mounted construction of dynamic digital mapping and comparison with the permitted levels of the exposure defined by the International Commission of Non Ionizing Radiation Protection ICNIRP. Through this publication the aim of the authors is to provide real information and reliable for the population.

Design of 1 MHz Solid State High Frequency Power Supply

Science.gov (United States)

Parmar, Darshan; Singh, N. P.; Gajjar, Sandip; Thakar, Aruna; Patel, Amit; Raval, Bhavin; Dhola, Hitesh; Dave, Rasesh; Upadhay, Dishang; Gupta, Vikrant; Goswami, Niranjan; Mehta, Kush; Baruah, Ujjwal

2017-04-01

High Frequency Power supply (HFPS) is used for various applications like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600 W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with Class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50ohm respectively. This paper describes the conceptual design of a 200 kW high frequency power supply and experimental results of the prototype 600 W, 1 MHz source.

Dual band multi frequency rectangular patch microstrip antenna with flyswatter shaped slot for wireless systems

International Nuclear Information System (INIS)

Bhardwaj, Dheeraj; Saraswat, Shriti; Gulati, Gitansh; Shekhar, Snehanshu; Joshi, Kanika; Sharma, Komal

2016-01-01

In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S_1_1) have been investigated. The antenna design is primarily focused on achieving a dual band operation.

Dual band multi frequency rectangular patch microstrip antenna with flyswatter shaped slot for wireless systems

Energy Technology Data Exchange (ETDEWEB)

Bhardwaj, Dheeraj, E-mail: dbhardwaj.bit@gmail.com [Department of Physics, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Saraswat, Shriti, E-mail: saraswat.srishti@gmail.com; Gulati, Gitansh, E-mail: gitanshgulati@gmail.com; Shekhar, Snehanshu, E-mail: snehanshushekhar.bit@gmail.com; Joshi, Kanika, E-mail: kanika.karesh@gmail.com [Department of Electronics & Communication, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Sharma, Komal, E-mail: kbhardwaj18@gmail.com [Department of Physics, Swami Keshvanand Institute of Technology, Jaipur 302017 (India)

2016-03-09

In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S{sub 11}) have been investigated. The antenna design is primarily focused on achieving a dual band operation.

Dual band multi frequency rectangular patch microstrip antenna with flyswatter shaped slot for wireless systems

Science.gov (United States)

Bhardwaj, Dheeraj; Saraswat, Shriti; Gulati, Gitansh; Shekhar, Snehanshu; Joshi, Kanika; Sharma, Komal

2016-03-01

In this paper a dual band planar antenna has been proposed for IEEE 802.16 Wi-MAX /IEEE 802.11 WLAN/4.9 GHz public safety applications. The antenna comprises a frequency bandwidth of 560MHz (3.37GHz-3.93GHz) for WLAN and WiMAX and 372MHz (4.82GHz-5.192GHz) for 4.9 GHz public safety applications and Radio astronomy services (4.8-4.94 GHz). The proposed antenna constitutes of a single microstrip patch reactively loaded with three identical steps positioned in a zig-zag manner towards the radiating edges of the patch. The coaxially fed patch antenna characteristics (radiation pattern, antenna gain, antenna directivity, current distribution, S11) have been investigated. The antenna design is primarily focused on achieving a dual band operation.

A Compact Frequency Reconfigurable Antenna for LTE Mobile Handset Applications

Directory of Open Access Journals (Sweden)

Munyong Choi

2015-01-01

Full Text Available A compact (8 × 62 × 5 mm3; 2.48 cc frequency reconfigurable antenna that uses electrical switching with PIN diodes is proposed for the low frequency LTE band (699 MHz–862 MHz, high frequency LTE band (2496 MHz–2690 MHz, GSM850/900 bands (824 MHz–960 MHz, and DCS/PCS/WCDMA bands (1710 MHz–2170 MHz. The penta-band PIFA is first designed for GSM850/900/DCS/PCS/WCDMA bands by using two slits and ground pins within a limited antenna volume (8 × 54.6 × 5 mm3; 2.18 cc. The frequency reconfigurable antenna based on this penta-band PIFA is thus proposed to additionally cover all LTE bands. The proposed antenna has two PIN diodes with an optimal location. For State 1 (PIN diode 1: ON state, PIN diode 2: OFF state, the proposed antenna covers the low frequency LTE band, DCS/PCS/WCDMA bands, and high frequency LTE band. For State 2 (PIN diode 1: OFF state, PIN diode 2: ON state, the antenna covers the GSM850/900 bands. Simulated and measured results show that the total efficiency of the proposed antenna was greater than 40% for all operating frequency bands.

47 CFR 15.250 - Operation of wideband systems within the band 5925-7250 MHz.

Science.gov (United States)

2010-10-01

... of wideband systems within the band 5925-7250 MHz. (a) The −10 dB bandwidth of a device operating... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation of wideband systems within the band... variations in temperature and supply voltage. (b) The −10 dB bandwidth of the fundamental emission shall be...

Programmable optical processor chips: toward photonic RF filters with DSP-level flexibility and MHz-band selectivity

Directory of Open Access Journals (Sweden)

Xie Yiwei

2017-12-01

Full Text Available Integrated optical signal processors have been identified as a powerful engine for optical processing of microwave signals. They enable wideband and stable signal processing operations on miniaturized chips with ultimate control precision. As a promising application, such processors enables photonic implementations of reconfigurable radio frequency (RF filters with wide design flexibility, large bandwidth, and high-frequency selectivity. This is a key technology for photonic-assisted RF front ends that opens a path to overcoming the bandwidth limitation of current digital electronics. Here, the recent progress of integrated optical signal processors for implementing such RF filters is reviewed. We highlight the use of a low-loss, high-index-contrast stoichiometric silicon nitride waveguide which promises to serve as a practical material platform for realizing high-performance optical signal processors and points toward photonic RF filters with digital signal processing (DSP-level flexibility, hundreds-GHz bandwidth, MHz-band frequency selectivity, and full system integration on a chip scale.

Interference Measurements in the European 868 MHz ISM Band with Focus on LoRa and SigFox

DEFF Research Database (Denmark)

Lauridsen, Mads; Vejlgaard, Benny; Kovács, István

2017-01-01

In this measurement study the signal activity and power levels are measured in the European Industrial, Scientific, and Medical band 863-870 MHz in the city of Aalborg, Denmark. The target is to determine if there is any interference, which may impact deployment of Internet of Things devices....... The focus is on the Low Power Wide Area technologies LoRa and SigFox. The measurements show that there is a 22-33 % probability of interfering signals above -105 dBm within the mandatory LoRa and SigFox 868.0-868.6 MHz band in a shopping area and a business park in downtown Aalborg, which thus limits...... the potential coverage and capacity of LoRa and SigFox. However, the probability of interference is less than 3 % in the three other measurement locations in Aalborg. Finally, a hospital and an industrial area are shown to experience high activity in the RFID subband 865-868 MHz, while the wireless audio band...

A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications

Directory of Open Access Journals (Sweden)

Syed Imran Hussain Shah

2017-11-01

Full Text Available In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900–1120 MHz and 15% (2.1–2.45 GHz for the unfolded state and 20% (1.3–1.6 GHz and 14% (2.3–2.5 GHz for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

A Dual Band Frequency Reconfigurable Origami Magic Cube Antenna for Wireless Sensor Network Applications.

Science.gov (United States)

Shah, Syed Imran Hussain; Lim, Sungjoon

2017-11-20

In this paper, a novel dual band frequency reconfigurable antenna using an origami magic cube is proposed for wireless sensor network (WSN) applications. The proposed origami antenna consists of a meandered monopole folded onto three sides of the magic cube. A microstrip open-ended stub is loaded on the meandered monopole. The proposed origami magic cube can be mechanically folded and unfolded. The proposed antenna operates at 1.57 GHZ and 2.4 GHz in the folded state. In the unfolded state, the proposed antenna operates at 900 MHz and 2.3 GHz. The resonant frequency of the second band can be tunable by varying the length and position of the open stub. The origami magic cube is built on paper. Its performance is numerically and experimentally demonstrated from S-parameters and radiation patterns. The measured 10 dB impedance bandwidth of the proposed origami antenna is 18% (900-1120 MHz) and 15% (2.1-2.45 GHz) for the unfolded state and 20% (1.3-1.6 GHz) and 14% (2.3-2.5 GHz) for the folded state. The measured peak gain at 900 MHz and 2.3 GHz are 1.1 dBi and 2.32 dBi, respectively, in the unfolded state. The measured peak gain at 1.5 GHz and 2.4 GHz are 3.28 dBi and 1.98 dBi, respectively, in the folded state.

Very high frequency (beyond 100 MHz) PZT kerfless linear arrays.

Science.gov (United States)

Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K Kirk

2009-10-01

This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-microm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-microm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss).

Design of 1 MHz solid state high frequency power supply

International Nuclear Information System (INIS)

Parmar, Darshan Kumar; Singh, N.P.; Gajjar, Sandip

2015-01-01

A High Voltage High Frequency (HVHF) Power supply is used for various applications, like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources, etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼ 1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50 ohm respectively. This paper describes the conceptual design of a 200 kW power supply and experimental results of the prototype 600 W, 1 MHz source. (author)

47 CFR 90.723 - Selection and assignment of frequencies.

Science.gov (United States)

2010-10-01

... 220-222 MHz Band § 90.723 Selection and assignment of frequencies. (a) Phase II applications for frequencies in the 220-222 MHz band shall specify whether their intended use is for 10-channel nationwide... medical use. Phase II applicants for frequencies for public safety/mutual aid use or emergency medical use...

Compact multi-band frequency reconfigurable planar monopole antenna for several wireless communication applications

Directory of Open Access Journals (Sweden)

M. Abou Al-Alaa

2014-05-01

Full Text Available A compact reconfigurable multi-band monopole antenna is presented. To achieve frequency reconfigurability, a PIN diode is used. There are two states of switch. State 1: when the switch is OFF, the antenna operates at four bands: 2.45, 3, 3.69, and 5.5 GHz with impedance bandwidth of 9.95, 5.96, 12.57, and 10.76%, respectively. State 2: when a switch is ON, the antenna operates at 2.64, 3.67, 4.94, and 5.3 GHz with impedance bandwidth of 21.15, 11.76, 5.79, and 4.12%, respectively. Folded and meandered techniques are used for miniaturize antenna size. Antenna size is 15 mm × 37 mm × 0.8 mm and the radiator part is 15 mm × 9 mm × 0.8 mm. The proposed antenna is used in several applications such as Bluetooth (2400–2484 MHz, WLAN [802.11b/g/n (2.4–2.48 GHz, 802.11y (3.657–3.69 GHz, 802.11y (4.9 GHz, 802.11a/h/j/n (5.2 GHz], Wi-MAX (2.5–2.69 GHz, LTE (band 7, band 38, band 41, and band 43 and S-DMB (2605–2655 MHz. The antenna is analyzed using the transient solver of CST Microwave Studio. The proposed antenna was fabricated and tested. Measurements and simulations show good agreement.

Resonance Frequency Readout Circuit for a 900 MHz SAW Device.

Science.gov (United States)

Liu, Heng; Zhang, Chun; Weng, Zhaoyang; Guo, Yanshu; Wang, Zhihua

2017-09-15

A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency searching strategy has been proposed based on the fact that the SAW device phase-frequency response crosses zero monotonically around the resonance frequency. A dedicated instant phase difference detecting circuit is adopted to facilitate the fast SAR operation for resonance frequency searching. The readout circuit has been implemented in 180 nm CMOS technology with a core area of 3.24 mm². In the experiment, it works with a 900 MHz SAW resonator with a quality factor of Q = 130. Experimental results show that the readout circuit consumes 7 mW power from 1.6 V supply. The frequency resolution is 733 Hz, and the relative accuracy is 0.82 ppm, and it takes 0.48 ms to complete one measurement. Compared to the previous results in the literature, this work has achieved the shortest measurement time with a trade-off between measurement accuracy and measurement time.

The Frequency Spectral Properties of Electrode-Skin Contact Impedance on Human Head and Its Frequency-Dependent Effects on Frequency-Difference EIT in Stroke Detection from 10Hz to 1MHz.

Directory of Open Access Journals (Sweden)

Lin Yang

Full Text Available Frequency-difference electrical impedance tomography (fdEIT reconstructs frequency-dependent changes of a complex impedance distribution. It has a potential application in acute stroke detection because there are significant differences in impedance spectra between stroke lesions and normal brain tissues. However, fdEIT suffers from the influences of electrode-skin contact impedance since contact impedance varies greatly with frequency. When using fdEIT to detect stroke, it is critical to know the degree of measurement errors or image artifacts caused by contact impedance. To our knowledge, no study has systematically investigated the frequency spectral properties of electrode-skin contact impedance on human head and its frequency-dependent effects on fdEIT used in stroke detection within a wide frequency band (10 Hz-1 MHz. In this study, we first measured and analyzed the frequency spectral properties of electrode-skin contact impedance on 47 human subjects' heads within 10 Hz-1 MHz. Then, we quantified the frequency-dependent effects of contact impedance on fdEIT in stroke detection in terms of the current distribution beneath the electrodes and the contact impedance imbalance between two measuring electrodes. The results showed that the contact impedance at high frequencies (>100 kHz significantly changed the current distribution beneath the electrode, leading to nonnegligible errors in boundary voltages and artifacts in reconstructed images. The contact impedance imbalance at low frequencies (<1 kHz also caused significant measurement errors. We conclude that the contact impedance has critical frequency-dependent influences on fdEIT and further studies on reducing such influences are necessary to improve the application of fdEIT in stroke detection.

The Frequency Spectral Properties of Electrode-Skin Contact Impedance on Human Head and Its Frequency-Dependent Effects on Frequency-Difference EIT in Stroke Detection from 10Hz to 1MHz.

Science.gov (United States)

Yang, Lin; Dai, Meng; Xu, Canhua; Zhang, Ge; Li, Weichen; Fu, Feng; Shi, Xuetao; Dong, Xiuzhen

2017-01-01

Frequency-difference electrical impedance tomography (fdEIT) reconstructs frequency-dependent changes of a complex impedance distribution. It has a potential application in acute stroke detection because there are significant differences in impedance spectra between stroke lesions and normal brain tissues. However, fdEIT suffers from the influences of electrode-skin contact impedance since contact impedance varies greatly with frequency. When using fdEIT to detect stroke, it is critical to know the degree of measurement errors or image artifacts caused by contact impedance. To our knowledge, no study has systematically investigated the frequency spectral properties of electrode-skin contact impedance on human head and its frequency-dependent effects on fdEIT used in stroke detection within a wide frequency band (10 Hz-1 MHz). In this study, we first measured and analyzed the frequency spectral properties of electrode-skin contact impedance on 47 human subjects' heads within 10 Hz-1 MHz. Then, we quantified the frequency-dependent effects of contact impedance on fdEIT in stroke detection in terms of the current distribution beneath the electrodes and the contact impedance imbalance between two measuring electrodes. The results showed that the contact impedance at high frequencies (>100 kHz) significantly changed the current distribution beneath the electrode, leading to nonnegligible errors in boundary voltages and artifacts in reconstructed images. The contact impedance imbalance at low frequencies (<1 kHz) also caused significant measurement errors. We conclude that the contact impedance has critical frequency-dependent influences on fdEIT and further studies on reducing such influences are necessary to improve the application of fdEIT in stroke detection.

78 FR 31472 - Wireless Telecommunications Bureau Seeks To Supplement the Record on the 600 MHz Band Plan

Science.gov (United States)

2013-05-24

... Telecommunications Bureau Seeks To Supplement the Record on the 600 MHz Band Plan AGENCY: Federal Communications... Telecommunications Bureau seeks further comment on how certain band plan approaches can best accommodate market... issued. Federal Communications Commission. Ruth Milkman, Chief. Wireless Telecommunications Bureau. [FR...

Quad-Band U-Slot Antenna for Mobile Applications

Directory of Open Access Journals (Sweden)

R. L. Ruiz

2006-06-01

Full Text Available In this paper, two different planar quad-band antennas are designed, modeled, fabricated and measured. Subsequently, the antennas are redesigned using an electromagnetic band gap substrate (EBG. Those new planar antennas operate in four frequency bands: 900 MHz, 1 800 MHz (both GSM, 1 900 MHz (USA and 2 400 to 2 500 MHz (Bluetooth The antenna has four narrow U-shaped slots etched to the patch. Using software, CST Microwave Studio [1], Zeland IE3D [2], and FEMLAB [3], simulations have been carried out to investigate the antenna's performance and characteristics. The antennas designed have been also built and measured to compare the real results with those obtained from the simulations.

Dual-band frequency selective surface with large band separation and stable performance

Science.gov (United States)

Zhou, Hang; Qu, Shao-Bo; Peng, Wei-Dong; Lin, Bao-Qin; Wang, Jia-Fu; Ma, Hua; Zhang, Jie-Qiu; Bai, Peng; Wang, Xu-Hua; Xu, Zhuo

2012-05-01

A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations.

47 CFR 101.147 - Frequency assignments.

Science.gov (United States)

2010-10-01

..., will be secondary to use of the band for emerging technology services. (22) Frequencies in these bands... video entertainment material. 932.00625/941.00625 MHz to 932.24375/941.24375 MHz is licensed by Economic... transmission of the licensee's products and information services, excluding video entertainment material to the...

Experimental Limits on Gravitational Waves in the MHz frequency Range

Energy Technology Data Exchange (ETDEWEB)

Lanza, Robert Jr. [Univ. of Chicago, IL (United States)

2015-03-01

This thesis presents the results of a search for gravitational waves in the 1-11MHz frequency range using dual power-recycled Michelson laser interferometers at Fermi National Accelerator Laboratory. An unprecedented level of sensitivity to gravitational waves in this frequency range has been achieved by cross-correlating the output fluctuations of two identical and colocated 40m long interferometers. This technique produces sensitivities better than two orders of magnitude below the quantum shot-noise limit, within integration times of less than 1 hour. 95% confidence level upper limits are placed on the strain amplitude of MHz frequency gravitational waves at the 10^-21 Hz^-1/2 level, constituting the best direct limits to date at these frequencies. For gravitational wave power distributed over this frequency range, a broadband upper limit of 2.4 x 10^-21Hz^-1/2 at 95% confidence level is also obtained. This thesis covers the detector technology, the commissioning and calibration of the instrument, the statistical data analysis, and the gravitational wave limit results. Particular attention is paid to the end-to-end calibration of the instrument’s sensitivity to differential arm length motion, and so to gravitational wave strain. A detailed statistical analysis of the data is presented as well.

Dual-band frequency selective surface with large band separation and stable performance

International Nuclear Information System (INIS)

Zhou Hang; Qu Shao-Bo; Lin Bao-Qin; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Peng Wei-Dong; Bai Peng; Wang Xu-Hua; Xu Zhuo

2012-01-01

A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Charge domain filter operating up to 20 MHz clock frequency

NARCIS (Netherlands)

Gal, R.A.J.; Wallinga, Hans

1983-01-01

An analog sampled data low pass third order Butterworth filter has been realised in a buried channel CCD technology. This Charge Domain Filter, composed of transversal and recursive CCD filter sections, has been tested at clock frequencies up to 20 MHz.

Printed Circuit Board Integrated Toroidal Radio Frequency Inductors

DEFF Research Database (Denmark)

Kamby, Peter; Knott, Arnold; Andersen, Michael A. E.

2012-01-01

Modern power semiconductors allow for switching frequencies of power converters in the very high frequency (VHF) band (30 MHz to 300 MHz). The major advantage of this frequency increase is a remarkable reduction of the size of power converters due to smaller passive components. However crucial...

Frequency Usage and Digital Dividend in India

DEFF Research Database (Denmark)

Patil, Kishor P.; Prasad, Ramjee; Skouby, Knud Erik

2013-01-01

, which could be the solution for the spectrum requirement for mobile telecom services in India. The views of the different stakeholders about 700 MHz band plan is presented. Finally, the two harmonized frequency arrangement for IMT systems agreed by the Asia Pacific Telecommunity (APT) for 700 MHz band...

47 CFR 74.690 - Transition of the 1990-2025 MHz band from the Broadcast Auxiliary Service to emerging technologies.

Science.gov (United States)

2010-10-01

... Broadcast Auxiliary Service to emerging technologies. 74.690 Section 74.690 Telecommunication FEDERAL... of the 1990-2025 MHz band from the Broadcast Auxiliary Service to emerging technologies. (a) New... licensed emerging technology services will maintain primary status in the band until the Existing Licensee...

A low frequency RFI monitoring system

Science.gov (United States)

Amiri, Shahram; Shankar, N. Udaya; Girish, B. S.; Somashekar, R.

Radio frequency interference (RFI) is a growing problem for research in radio astronomy particularly at wavelengths longer than 2m. For satisfactory operation of a radio telescope, several bands have been protected for radio astronomy observations by the International Telecommunication Union. Since the radiation from cosmic sources are typically 40 to 100 dB below the emission from services operating in unprotected bands, often the out-of-band emission limits the sensitivity of astronomical observations. Moreover, several radio spectral emissions from cosmic sources are present in the frequency range outside the allocated band for radio astronomy. Thus monitoring of RFI is essential before building a receiver system for low frequency radio astronomy. We describe the design and development of an RFI monitoring system operating in the frequency band 30 to 100 MHz. This was designed keeping in view our proposal to extend the frequency of operation of GMRT down to 40 MHz. The monitor is a PC based spectrometer recording the voltage output of a receiver connected to an antenna, capable of digitizing the low frequency RF directly with an 8 bit ADC and sampling bandwidths up to 16 MHz. The system can operate continuously in almost real-time with a loss of only 2% of data. Here we will present the systems design aspects and the results of RFI monitoring carried out at the Raman Research Institute, Bangalore and at the GMRT site in Khodad.

Mars Global Surveyor Ka-Band Frequency Data Analysis

Science.gov (United States)

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

2000-01-01

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

A reconfigurable complex band-pass filter with improved passive compensation

International Nuclear Information System (INIS)

Fan Chaojie; Mo Tingting; Chen Dongpo; Zhou Jianjun

2012-01-01

This paper presents a 5th-order Chebyshev-I active RC complex filter for multi-mode multi-band global navigation satellite systems (GNSS) RF receivers. An improved passive compensation technique is used to cancel the excess phase lag of the integrators, thus ensuring the in-band flatness of the frequency response over various ambient conditions. The filter has a programmable gain from 0 to 42 dB with a 6 dB step, a tunable center frequency at either 6.4 MHz or 16 MHz, and a bandwidth from 2 to 20 MHz with less than 3% frequency uncertainty. Implemented in a 0.18 μm CMOS process, the whole filter consumes 7.8 mA from a 1.8 V supply voltage and occupies a die area of 0.4 mm 2 . (semiconductor integrated circuits)

Evaluation of a 433 MHz Band Body Sensor Network for Biomedical Applications

Science.gov (United States)

Kim, Saim; Brendle, Christian; Lee, Hyun-Young; Walter, Marian; Gloeggler, Sigrid; Krueger, Stefan; Leonhardt, Steffen

2013-01-01

Body sensor networks (BSN) are an important research topic due to various advantages over conventional measurement equipment. One main advantage is the feasibility to deploy a BSN system for 24/7 health monitoring applications. The requirements for such an application are miniaturization of the network nodes and the use of wireless data transmission technologies to ensure wearability and ease of use. Therefore, the reliability of such a system depends on the quality of the wireless data transmission. At present, most BSNs use ZigBee or other IEEE 802.15.4 based transmission technologies. Here, we evaluated the performance of a wireless transmission system of a novel BSN for biomedical applications in the 433 MHz ISM band, called Integrated Posture and Activity NEtwork by Medit Aachen (IPANEMA) BSN. The 433 MHz ISM band is used mostly by implanted sensors and thus allows easy integration of such into the BSN. Multiple measurement scenarios have been assessed, including varying antenna orientations, transmission distances and the number of network participants. The mean packet loss rate (PLR) was 0.63% for a single slave, which is comparable to IEEE 802.15.4 BSNs in the proximity of Bluetooth or WiFi networks. Secondly, an enhanced version is evaluated during on-body measurements with five slaves. The mean PLR results show a comparable good performance for measurements on a treadmill (2.5%), an outdoor track (3.4%) and in a climate chamber (1.5%). PMID:23344383

Effects of 415 MHz frequency on human lymphocyte genome

International Nuclear Information System (INIS)

Garaj-Vrhovac, V.; Fucic, A.; Kubelka, D.; Vojvodic, S.

1996-01-01

The continuously increasing use of artificial sources of electromagnetic radiation in industry and medicine has been accompanied in everyday life with telecommunication systems which is followed with great interest in possible hazardous effects of this type of radiation. The interesting applications of mobile telecommunications and the use of cellular phones are of topic interest. Numerous cytogenetic investigations are focused on the effects of microwave radiation from mobile communications frequency of 450 and 950 MHz on isolated cells in vitro. The aim of this work was to investigate the effects of microwaves from mobile telephone frequencies on human peripheral blood lymphocytes cultured in vitro. (author)

Fundamental Frequency Tuning and Its Influence on LHC 200MHz ACN Cavity

CERN Document Server

Linnecar, Trevor Paul R; Tückmantel, Joachim; CERN. Geneva. SPS and LHC Division

2001-01-01

To study the influence of the tuner on the fundamental mode frequency, the Q factor as well as the shunt impedance of the LHC 200MHz ACN cavities, 3D simulations have been done in the frequency domain using MAFIA. Curves giving the variation of RF frequency and other RF parameters with tuner position relative to the inner surface of the cavity have been obtained for the fundamental mode. This paper details the simulation results.

Thrombolysis using multi-frequency high intensity focused ultrasound at MHz range: an in vitro study

International Nuclear Information System (INIS)

Suo, Dingjie; Guo, Sijia; Jiang, Xiaoning; Jing, Yun; Lin, Weili

2015-01-01

High intensity focused ultrasound (HIFU) based thrombolysis has emerged as a promising drug-free treatment approach for ischemic stroke. The large amount of acoustic power required by this approach, however, poses a critical challenge to the future clinical translation. In this study, multi-frequency acoustic waves at MHz range (near 1.5 MHz) were introduced as HIFU excitations to reduce the required power for treatment as well as the treatment time. In vitro bovine blood clots weighing around 150 mg were treated by single-frequency and multi-frequency HIFU. The pulse length was 2 ms for all experiments except the ones where the duty cycle was changed. It was found that dual-frequency thrombolysis efficiency was statistically better than single-frequency under the same acoustic power and excitation condition. When varying the acoustic power but fixing the duty cycle at 5%, it was found that dual-frequency ultrasound can save almost 30% power in order to achieve the same thrombolysis efficiency. In the experiment where the duty cycle was increased from 0.5% to 10%, it was shown that dual-frequency ultrasound can achieve the same thrombolysis efficiency with only half of the duty cycle of single-frequency. Dual-frequency ultrasound could also accelerate the thrombolysis by a factor of 2–4 as demonstrated in this study. No significant differences were found between dual-frequencies with different frequency differences (0.025, 0.05, and 0.1 MHz) and between dual-frequency and triple-frequency. The measured cavitation doses of dual-frequency and triple-frequency excitations were at about the same level but both were significantly higher than that of single-frequency. (paper)

Sustaining GHz oscillation of carbon nanotube based oscillators via a MHz frequency excitation

International Nuclear Information System (INIS)

Motevalli, Benyamin; Taherifar, Neda; Liu, Jefferson Zhe

2016-01-01

There have been intensive studies to investigate the properties of gigahertz nano-oscillators based on multi-walled carbon nanotubes (MWCNTs). Many of these studies, however, revealed that the unique telescopic translational oscillations in such devices would damp quickly due to various energy dissipation mechanisms. This challenge remains the primary obstacle against its practical applications. Herein, we propose a design concept in which a GHz oscillation could be re-excited by a MHz mechanical motion. This design involves a triple-walled CNT, in which sliding of the longer inner tube at a MHz frequency can re-excite and sustain a GHz oscillation of the shorter middle tube. Our molecular dynamics (MD) simulations prove this design concept at ∼10 nm scale. A mathematical model is developed to explore the feasibility at a larger size scale. As an example, in an oscillatory system with the CNT’s length above 100 nm, the high oscillatory frequency range of 1.8–3.3 GHz could be excited by moving the inner tube at a much lower frequency of 53.4 MHz. This design concept together with the mechanical model could energize the development of GHz nano-oscillators in miniaturized electro-mechanical devices. (paper)

47 CFR 25.147 - Licensing provision for NGSO MSS feeder downlinks in the band 6700-6875 MHz.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provision for NGSO MSS feeder downlinks in the band 6700-6875 MHz. 25.147 Section 25.147 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Space...

DC feedback for wide band frequency fixed current source

Directory of Open Access Journals (Sweden)

Aoday Hashim Mohamad Al-Rawi

2013-03-01

Full Text Available Alternating current sources are mainly used in bioelectrical impedance devices. Nowadays 50 – 100 kHz bioelectrical impedance devices are commonly used for body composition analysis. High frequency bioelectrical impedance analysis devices are mostly used in bioimpedance tomography and blood analysis. High speed op-amps and voltage comparators are used in this circuit. Direct current feedback is used to prevent delay. An N-Channel J-FET transistor was used to establish the voltage controlled gain amplifier (VCG. A sine wave signal has been applied as input voltage. The value of this signal should be constant in 170 mV rms to keep the output current in about 1 mA rms. Four frequencies; 100 kHz, 1 MHz, 2 MHz and 3.2 MHz were applied to the circuit and the current was measured for different load resistances. The results showed that the current was stable for changes in the resistor load, bouncing around an average point as a result of bouncing DC feedback.

RRI-GBT MULTI-BAND RECEIVER: MOTIVATION, DESIGN, AND DEVELOPMENT

International Nuclear Information System (INIS)

Maan, Yogesh; Deshpande, Avinash A.; Chandrashekar, Vinutha; Chennamangalam, Jayanth; Rao, K. B. Raghavendra; Somashekar, R.; Ezhilarasi, M. S.; Sujatha, S.; Kasturi, S.; Sandhya, P.; Duraichelvan, R.; Amiri, Shahram; Aswathappa, H. A.; Sarabagopalan, G.; Ananda, H. M.; Anderson, Gary; Bauserman, Jonah; Beaudet, Carla; Bloss, Marty; Barve, Indrajit V.

2013-01-01

We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive and high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively radio frequency interference free), a common wide-band radio frequency front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Robert C. Byrd Green Bank Telescope using this receiver. The system performance implied by these results and possible improvements are also briefly discussed.

RRI-GBT MULTI-BAND RECEIVER: MOTIVATION, DESIGN, AND DEVELOPMENT

Energy Technology Data Exchange (ETDEWEB)

Maan, Yogesh; Deshpande, Avinash A.; Chandrashekar, Vinutha; Chennamangalam, Jayanth; Rao, K. B. Raghavendra; Somashekar, R.; Ezhilarasi, M. S.; Sujatha, S.; Kasturi, S.; Sandhya, P.; Duraichelvan, R.; Amiri, Shahram; Aswathappa, H. A.; Sarabagopalan, G.; Ananda, H. M. [Raman Research Institute, Bangalore (India); Anderson, Gary; Bauserman, Jonah; Beaudet, Carla; Bloss, Marty [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV (United States); Barve, Indrajit V. [Indian Institute of Astrophysics, Bangalore (India); and others

2013-01-15

We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive and high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively radio frequency interference free), a common wide-band radio frequency front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Robert C. Byrd Green Bank Telescope using this receiver. The system performance implied by these results and possible improvements are also briefly discussed.

Multiband Planar Inverted-F Antenna with Independent Operating Bands Control for Mobile Handset Applications

Directory of Open Access Journals (Sweden)

Mustapha El Halaoui

2017-01-01

Full Text Available A new compact multiband PIFA (Planar Inverted-F Antenna for mobile handset is proposed in this article. The proposed PIFA has a simple geometry with four slots integrated in the radiating patch and ground plane. The PIFA occupies a small volume of 51 × 14 × 7.2 mm3 and is placed on the top portion of mobile phone. The optimized PIFA is worked in the 790 MHz band (737–831 MHz, the 1870 MHz band (1794–1977 MHz, the 2550 MHz band (2507–2615 MHz, and the 3400 MHz band (3341–3545 MHz, to cover LTE700, LTE800, DCS1800, PCS1900, LTE1800, LTE1900, LTE2500, and WIMAX3400 bands. Each of the four operating bands can be controlled independently by the variation of a single parameter of the proposed design, with a wide control range. An omnidirectional radiation pattern to each resonant frequency is obtained with a maximum gain of 2.15 dBi at 790 MHz, 3.99 dBi at 1870 MHz, 4.57 dBi at 2550 MHz, and 6.43 dBi at 3400 MHz. The proposed PIFA is studied in the free space and in the presence of other mobile phone components such as the battery, LCD (liquid crystal display, camera, microphone, speaker, buttons, and a plastic housing. The distribution of specific absorption rate for both European and American standards for each operating band and at various distances between the antenna and the human head is also studied.

Design Study for 10MHz Beam Frequency of Post-Accelerated RIBs at HIE-ISOLDE

CERN Document Server

Fraser, M A; Magdau, I B

2013-01-01

An increased bunch spacing of approximately 100 ns is requested by several research groups targeting experimental physics at HIE-ISOLDE. A design study testing the feasibility of retrofitting the existing 101.28MHz REX (Radioactive ion beam EXperiment) RFQ [1] with a subharmonic external pre-buncher at the ISOLDE radioactive nuclear beam facility has been carried out as a means of decreasing the beam frequency by a factor of 10. The proposed scheme for the 10MHz bunch repetition frequency is presented and its performance assessed with beam dynamics simulations. The opportunity to reduce the longitudinal emittance formed in the RFQ is discussed along with the options for chopping the satellite bunches populated in the bunching process.

Measuring personal exposure from 900MHz mobile phone base stations in Australia and Belgium using a novel personal distributed exposimeter

NARCIS (Netherlands)

Bhatt, Chhavi Raj; Thielens, Arno; Redmayne, Mary; Abramson, Michael J; Billah, Baki; Sim, Malcolm R; Vermeulen, Roel; Martens, Luc; Joseph, Wout; Benke, Geza

2016-01-01

The aims of this study were to: i) measure personal exposure in the Global System for Mobile communications (GSM) 900MHz downlink (DL) frequency band with two systems of exposimeters, a personal distributed exposimeter (PDE) and a pair of ExpoM-RFs, ii) compare the GSM 900MHz DL exposures across

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

Science.gov (United States)

Wintucky, Edwin G.; Simons, Rainee N.

2015-01-01

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

47 CFR 18.303 - Prohibited frequency bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Prohibited frequency bands. 18.303 Section 18.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT Technical Standards § 18.303 Prohibited frequency bands. Operation of ISM equipment within the...

Simulation and fabrication of 0-3 composite PZT films for ultrahigh frequency (100-300 MHz) ultrasonic transducers

Science.gov (United States)

Chen, Xiaoyang; Fei, Chunlong; Chen, Zeyu; Chen, Ruimin; Yu, Ping; Chen, Zhongping; Shung, K. Kirk; Zhou, Qifa

2016-03-01

This paper presents simulation, fabrication, and characterization of single-element ultrahigh frequency (100-300-MHz) needle ultrasonic transducers based on 0-3 composite Pb(Zr0.52Ti0.48)O3 (PZT) films prepared by using composite ceramic sol-gel film and sol-infiltration technique. The center frequency of the developed transducer at 300-MHz was the highest frequency of PbTiO3 ceramic-based ultrasonic transducers ever reported. Furthermore, a brief description of the composite model was followed by the development of a new expression for predicting the longitudinal velocity, the clamped dielectric constant, and the complex electromechanical coupling coefficient kt of these films, which is very important in ultrasonic transducer design. Moreover, these parameters are difficult to obtain by measuring the frequency dependence of impedance and phase angle because of the weak signal of the previous 0-3 composite films transducer (>100 MHz). The modeling results show that the Cubes model with a geometric factor n = 0.05 fits well with the measured data. This model will be helpful for developing the 0-3 composite systems for ultrahigh frequency ultrasonic transducer design.

Design and Realization of FIR Filter for Inter Satellite Link at 50-90 MHZ Frequency using FPGA

Directory of Open Access Journals (Sweden)

Yuyu Wahyu

2016-12-01

Full Text Available In this paper, design and realization of FIR filter with a bandwidth of 40 MHz at 50-90 MHz frequency has been proposed. The design was destined to be implemented on the Inter Satellite Links (ISL. This kind of filter had been selected due to a need in linear phase responseon the ISL data communication. Equiripple method was used to design the filter becauseof its reliability in minimizing the magnitude errors. The design of this FIR filter was conducted with theoretical calculation and simulation using the R2012b Matlab. For the implementation, FPGA was used with a VHDL as the programming language with a help of Xilinx ISE Design Suite 14.5. Simulation results in Matlab and Simulink indicated that the filter design could be well implemented on ISL at frequency of 50 MHz - 90 MHz with stopband of 60 db. The phase responseresult of the realized design is quite linear so that the filter is suitable for data communication on the ISL.

47 CFR 90.615 - Individual channels available in the General Category in 806-824/851-869 MHz band.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Individual channels available in the General Category in 806-824/851-869 MHz band. 90.615 Section 90.615 Telecommunication FEDERAL COMMUNICATIONS... Critical Infrastructure Industry Categories from three to five years after the release of a public notice...

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

Science.gov (United States)

Downey, Joseph A.; Downey, James M.; Reinhart, Richard C.; Evans, Michael A.; Mortensen, Dale J.

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 2/4/8-phase shift keying (PSK) and 16/32- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 b/s/Hz) modulation combined with various LDPC encoding rates to maximize through- put. With a symbol rate of 200 M-band, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results

Radio frequency electromagnetic field compliance assessment of multi-band and MIMO equipped radio base stations.

Science.gov (United States)

Thors, Björn; Thielens, Arno; Fridén, Jonas; Colombi, Davide; Törnevik, Christer; Vermeeren, Günter; Martens, Luc; Joseph, Wout

2014-05-01

In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances. © 2014 Wiley Periodicals, Inc.

Low profile frequency agile MIMO slot antenna with TCM characterization

KAUST Repository

Ghalib, Asim

2017-06-07

In this paper, a frequency reconfigurable multiple-input-multiple-output (MIMO) slot antenna is presented. The proposed design is low profile and compact with wide tunability range, covering several well-known frequency bands from 1800 MHz to 2450 MHz. The frequency reconfigurability is achieved by loading the annular slot with varactor diodes. The antenna system is also analyzed for MIMO performance metrics. Moreover, the effect of circular slot antenna on the chassis modes is also investigated using the theory of characteristic modes (TCM). The physical principle behind frequency reconfigurability is also investigated using TCM analysis. An interesting finding is observed using varactor diodes for frequency reconfigurability, that is the reactive impedance loading does not alter the modal significance (MS) plots but only aid in the input impedance matching at different frequency bands.

Challenges and regulatory considerations in the acoustic measurement of high-frequency (>20 MHz) ultrasound.

Science.gov (United States)

Nagle, Samuel M; Sundar, Guru; Schafer, Mark E; Harris, Gerald R; Vaezy, Shahram; Gessert, James M; Howard, Samuel M; Moore, Mary K; Eaton, Richard M

2013-11-01

This article examines the challenges associated with making acoustic output measurements at high ultrasound frequencies (>20 MHz) in the context of regulatory considerations contained in the US Food and Drug Administration industry guidance document for diagnostic ultrasound devices. Error sources in the acoustic measurement, including hydrophone calibration and spatial averaging, nonlinear distortion, and mechanical alignment, are evaluated, and the limitations of currently available acoustic measurement instruments are discussed. An uncertainty analysis of acoustic intensity and power measurements is presented, and an example uncertainty calculation is done on a hypothetical 30-MHz high-frequency ultrasound system. This analysis concludes that the estimated measurement uncertainty of the acoustic intensity is +73%/-86%, and the uncertainty in the mechanical index is +37%/-43%. These values exceed the respective levels in the Food and Drug Administration guidance document of 30% and 15%, respectively, which are more representative of the measurement uncertainty associated with characterizing lower-frequency ultrasound systems. Recommendations made for minimizing the measurement uncertainty include implementing a mechanical positioning system that has sufficient repeatability and precision, reconstructing the time-pressure waveform via deconvolution using the hydrophone frequency response, and correcting for hydrophone spatial averaging.

IMPROVED DETERMINATION OF THE 1{sub 0}-0{sub 0} ROTATIONAL FREQUENCY OF NH{sub 3}D{sup +} FROM THE HIGH-RESOLUTION SPECTRUM OF THE {nu}{sub 4} INFRARED BAND

Energy Technology Data Exchange (ETDEWEB)

Domenech, J. L.; Cueto, M.; Herrero, V. J.; Tanarro, I. [Molecular Physics Department, Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, E-28006 Madrid (Spain); Tercero, B.; Cernicharo, J. [Department of Astrophysics, CAB, INTA-CSIC, Crta Torrejon-Ajalvir Km 4, E-28850 Torrejon de Ardoz, Madrid (Spain); Fuente, A., E-mail: jl.domenech@csic.es [Observatorio Astronomico Nacional, Apdo. 112, E-28803 Alcala de Henares (Spain)

2013-07-01

The high-resolution spectrum of the {nu}{sub 4} band of NH{sub 3}D{sup +} has been measured by difference frequency IR laser spectroscopy in a multipass hollow cathode discharge cell. From the set of molecular constants obtained from the analysis of the spectrum, a value of 262817 {+-} 6 MHz ({+-}3{sigma}) has been derived for the frequency of the 1{sub 0}-0{sub 0} rotational transition. This value supports the assignment to NH{sub 3}D{sup +} of lines at 262816.7 MHz recorded in radio astronomy observations in Orion-IRc2 and the cold prestellar core B1-bS.

47 CFR 27.16 - Network access requirements for Block C in the 746-757 and 776-787 MHz bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Network access requirements for Block C in the 746-757 and 776-787 MHz bands. 27.16 Section 27.16 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... network restrictions on industry-wide consensus standards, such restrictions would be presumed reasonable...

A CPW-fed Triple-band Antenna for WLAN and WiMAX Applications

Directory of Open Access Journals (Sweden)

X.L.Yang

2014-12-01

Full Text Available In this letter, a compact printed antenna fed by coplanar waveguide for triple-band is presented. The proposed antenna consists of two rectangular metallic loops in front and a slit square ring on the backside. Tri-band has been achieved, which can be easily tuned by adjusting the sizes of the rectangles. An analysis of equal lumped circuit mechanism as well the triple band operation is provided. Key parameters to tune the resonant frequencies have been identified. The overall dimension of the proposed antenna is 30×26 mm^2. Simulated results show that the presented antenna can cover three separated impedance bandwidths of ～13% at 300 MHz (2.2–2.5 GHz, ～14% at 500 MHz (3.3–3.8 GHz, and ～15% at 800 MHz (5.1–5.9 GHz, which are well applied for both 2.4/5.2/5.8-GHz WLAN bands and 3.5/5.5-GHz WiMAX bands.

Novel structural flexibility identification in narrow frequency bands

International Nuclear Information System (INIS)

Zhang, J; Moon, F L

2012-01-01

A ‘Sub-PolyMAX’ method is proposed in this paper not only for estimating modal parameters, but also for identifying structural flexibility by processing the impact test data in narrow frequency bands. The traditional PolyMAX method obtains denominator polynomial coefficients by minimizing the least square (LS) errors of frequency response function (FRF) estimates over the whole frequency range, but FRF peaks in different structural modes may have different levels of magnitude, which leads to the modal parameters identified for the modes with small FRF peaks being inaccurate. In contrast, the proposed Sub-PolyMAX method implements the LS solver in each subspace of the whole frequency range separately; thus the results identified from a narrow frequency band are not affected by FRF data in other frequency bands. In performing structural identification in narrow frequency bands, not in the whole frequency space, the proposed method has the following merits: (1) it produces accurate modal parameters, even for the modes with very small FRF peaks; (2) it significantly reduces computation cost by reducing the number of frequency lines and the model order in each LS implementation; (3) it accurately identifies structural flexibility from impact test data, from which structural deflection under any static load can be predicted. Numerical and laboratory examples are investigated to verify the effectiveness of the proposed method. (paper)

53 MHZ Feedforward beam loading compensation in the Fermilab main injector

International Nuclear Information System (INIS)

Joseph E Dey et al.

2003-01-01

53 MHz feedforward beam loading compensation is crucial to all operations of the Main Injector. Recently a system using a fundamental frequency down converter mixer, a digital bucket delay module and a fundamental frequency up converter mixer were used to produce a one-turn-delay feedforward signal. This signal was then combined with the low level RF signal to the cavities to cancel the transient beam induced voltage. During operation they have shown consistently over 20 dB reduction in side-band voltage around the fundamental frequency during Proton coalescing and over 14 dB in multi-batch antiproton coalescing

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

Science.gov (United States)

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

Improving mental task classification by adding high frequency band information.

Science.gov (United States)

Zhang, Li; He, Wei; He, Chuanhong; Wang, Ping

2010-02-01

Features extracted from delta, theta, alpha, beta and gamma bands spanning low frequency range are commonly used to classify scalp-recorded electroencephalogram (EEG) for designing brain-computer interface (BCI) and higher frequencies are often neglected as noise. In this paper, we implemented an experimental validation to demonstrate that high frequency components could provide helpful information for improving the performance of the mental task based BCI. Electromyography (EMG) and electrooculography (EOG) artifacts were removed by using blind source separation (BSS) techniques. Frequency band powers and asymmetry ratios from the high frequency band (40-100 Hz) together with those from the lower frequency bands were used to represent EEG features. Finally, Fisher discriminant analysis (FDA) combining with Mahalanobis distance were used as the classifier. In this study, four types of classifications were performed using EEG signals recorded from four subjects during five mental tasks. We obtained significantly higher classification accuracy by adding the high frequency band features compared to using the low frequency bands alone, which demonstrated that the information in high frequency components from scalp-recorded EEG is valuable for the mental task based BCI.

Low frequency electromagnetic field sensor

International Nuclear Information System (INIS)

Zhu Min; Zhou Yan; He Yicheng; Zheng Zhenxing; Liu Sunkun

2000-01-01

The measurement technique of low frequency electromagnetic field is reported. According to this principle, the authors have designed a sensor, which is used to measure the natural electromagnetic field, SLEMP and electromagnetic signals generated by some explosions. The frequency band of this sensor is from 0.08 Hz to 2 MHz

OLFAR - Orbiting low frequency antennas for radio astronomy

NARCIS (Netherlands)

Bentum, Marinus Jan

2013-01-01

One of the last unexplored frequency ranges in radio astronomy is the frequency band below 30 MHz. New interesting astronomical science drivers for low frequency radio astronomy have emerged, ranging from studies of the astronomical dark ages, the epoch of reionization, exoplanets, to ultra-high

The RFI situation for a space-based low-frequency radio astronomy instrument

NARCIS (Netherlands)

Bentum, Marinus Jan; Boonstra, A.J.

2016-01-01

Space based ultra-long wavelength radio astronomy has recently gained a lot of interest. Techniques to open the virtually unexplored frequency band below 30 MHz are becoming within reach at this moment. Due to the ionosphere and the radio interference (RFI) on Earth exploring this frequency band

Radio quite site qualification for the Brasilian Southern Space Observatory by monitoring the low frequency 10-240 MHz Eletromagnetic Spectrum

Science.gov (United States)

da Rosa, Guilherme Simon; Schuch, Nelson Jorge; Espindola Antunes, Cassio; Gomes, Natanael

The monitoring of the level of the radio interference in the Site of the Brazilian Southern Space Observatory - SSO/CRS/CIE/INPE - MCT, (29S, 53W), São Martinho da Serra, RS, in south a of Brazil, aims to gather spectral data for the Observatory's Site qualification as a radio quite site for installation of Radio Astronomy instrumentation, free of radio noise. The determination of the radio interference level is being conducted by using a spectrum analyzer and Omni directional antennas remotely controlled through a GPIB interface, via IEEE 488 bus, and programs written in C language. That procedure allows the scanning of the Electromagnetic Spectrum power over the examined frequency range from 10 - 240MHz. The methodology for these tests was to amplify the radio signal from the antenna by a block amplifier. Subsequently, the received signals are evaluated by the spectrum analyzer. A dedicated PC computer is used for the control and data acquisition, with the developed software. The data are instantly stored in digital format and remotely transferred via VNC software from the SSO-Observatory Site to the Radio Frequency and Telecommunication Laboratory at the Southern Regional Space Research Center - CRS/CIE/INPE - MCT, in Santa Maria, RS, for analysis and storage on the radio interference data base for long period. It is compared the SSO's Electromagnetic Spectrum data obtained since the beginning of the 1990's decade, before the Site constructions, with the current observed data. Some radio transmissions were found in the observed frequency range due to some local FMs, mostly between 93.5 MHz to 105.7 MHz, which were observed in previous monitoring. A good evidence of the site quality is the fact that the power of the Electromagnetic Spectrum is much lower than that measured at the Radio Frequency and Telecommunication Laboratory, in Santa Maria, RS, where the signals do not exceed -60 dB. On the Site of the SSO, due to the low power observed, weak radio signals

Amplitude of Low-Frequency Fluctuations in Multiple-Frequency Bands in Acute Mild Traumatic Brain Injury.

Science.gov (United States)

Zhan, Jie; Gao, Lei; Zhou, Fuqing; Bai, Lijun; Kuang, Hongmei; He, Laichang; Zeng, Xianjun; Gong, Honghan

2016-01-01

Functional disconnectivity during the resting state has been observed in mild traumatic brain injury (mTBI) patients during the acute stage. However, it remains largely unknown whether the abnormalities are related to specific frequency bands of the low-frequency oscillations (LFO). Here, we used the amplitude of low-frequency fluctuations (ALFF) to examine the amplitudes of LFO in different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; and typical: 0.01-0.08 Hz) in patients with acute mTBI. A total of 24 acute mTBI patients and 24 age-, sex-, and education-matched healthy controls participated in this study. In the typical band, acute mTBI patients showed lower standardized ALFF in the right middle frontal gyrus and higher standardized ALFF in the right lingual/fusiform gyrus and left middle occipital gyrus. Further analyses showed that the difference between groups was concentrated in a narrower (slow-4) frequency band. In the slow-5 band, mTBI patients only exhibited higher standardized ALFF in the occipital areas. No significant correlation between the mini-mental state examination score and the standardized ALFF value was found in any brain region in the three frequency bands. Finally, no significant interaction between frequency bands and groups was found in any brain region. We concluded that the abnormality of spontaneous brain activity in acute mTBI patients existed in the frontal lobe as well as in distributed brain regions associated with integrative, sensory, and emotional roles, and the abnormal spontaneous neuronal activity in different brain regions could be better detected by the slow-4 band. These findings might contribute to a better understanding of local neural psychopathology of acute mTBI. Future studies should take the frequency bands into account when measuring intrinsic brain activity of mTBI patients.

Amplitude of low-frequency fluctuations in multiple-frequency bands in acute mild traumatic brain injury

Directory of Open Access Journals (Sweden)

Jie eZhan

2016-02-01

Full Text Available Functional disconnectivity during the resting state has been observed in mild traumatic brain injury (mTBI patients during the acute stage. However, it remains largely unknown whether the abnormalities are related to specific frequency bands of the low-frequency oscillations (LFO. Here, we used the amplitude of low-frequency fluctuations (ALFF to examine the amplitudes of LFO in different frequency bands (slow-5: 0.01–0.027 Hz; slow-4: 0.027–0.073 Hz; and typical: 0.01–0.08 Hz in patients with acute mTBI. A total of 24 acute mTBI patients and 24 age-, sex-, and education-matched healthy controls (HC participated in this study. In the typical band, acute mTBI patients showed lower standardized ALFF in the right middle frontal gyrus and higher standardized ALFF in the right lingual/fusiform gyrus and left middle occipital gyrus. Further analyses showed that the difference between groups was concentrated in a narrower (slow-4 frequency band. In the slow-5 band, mTBI patients only exhibited higher standardized ALFF in the occipital areas. No significant correlation between the MMSE score and the standardized ALFF value was found in any brain region in the three frequency bands. Finally, no significant interaction between frequency bands and groups was found in any brain region. We concluded that the abnormality of spontaneous brain activity in acute mTBI patients existed in the frontal lobe as well as in distributed brain regions associated with integrative, sensory and emotional roles, and the abnormal spontaneous neuronal activity in different brain regions could be better detected by the slow-4 band. These findings might contribute to a better understanding of local neural psychopathology of acute mTBI. Future studies should take the frequency bands into account when measuring intrinsic brain activity of mTBI patients.

The Noisiness of Low Frequency Bands of Noise

Science.gov (United States)

Lawton, B. W.

1975-01-01

The relative noisiness of low frequency 1/3-octave bands of noise was examined. The frequency range investigated was bounded by the bands centered at 25 and 200 Hz, with intensities ranging from 50 to 95 db (SPL). Thirty-two subjects used a method of adjustment technique, producing comparison band intensities as noisy as 100 and 200 Hz standard bands at 60 and 72 db. The work resulted in contours of equal noisiness for 1/3-octave bands, ranging in intensity from approximately 58 to 86 db (SPL). These contours were compared with the standard equal noisiness contours; in the region of overlap, between 50 and 200 Hz, the agreement was good.

Dual Band Planar Inverted F Antenna (PIFA with L-Shape Configuration

Directory of Open Access Journals (Sweden)

khlouf Munzer Mohamad

2017-01-01

Full Text Available One of the most used antennas in mobile devices is planar inverted F antenna (PIFA. PIFA can be design in dual band frequencies due to the coverage of the wireless service in a mobile device that requires a multiple frequencies. However, the consideration of technical operation has to be combined with an evaluation of the antenna radiation impact on the users. A procedure of PIFA work in GSM (867-960MHz and GSM (1710-1899MHz is done using CST Software. The dual band frequency response is obtained by means of an insertion of an L-shaped slot, which is use to tune the operation frequencies. The prototype of the antenna is fabricated as model by CST Software and evaluated. It is found out that the PIFA antenna has a good efficiency, bandwidth as well as produce a maximum gain for the antenna. A key and innovative research is still underway to broaden performance parameters of the antenna.

1.55-μm mode-locked quantum-dot lasers with 300 MHz frequency tuning range

Energy Technology Data Exchange (ETDEWEB)

Sadeev, T., E-mail: tagir@mailbox.tu-berlin.de; Arsenijević, D.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, 10623 Berlin (Germany); Franke, D.; Kreissl, J.; Künzel, H. [Heinrich-Hertz-Institut, Einsteinufer 37, 10587 Berlin (Germany)

2015-01-19

Passive mode-locking of two-section quantum-dot mode-locked lasers grown by metalorganic vapor phase epitaxy on InP is reported. 1250-μm long lasers exhibit a wide tuning range of 300 MHz around the fundamental mode-locking frequency of 33.48 GHz. The frequency tuning is achieved by varying the reverse bias of the saturable absorber from 0 to −2.2 V and the gain section current from 90 to 280 mA. 3 dB optical spectra width of 6–7 nm leads to ex-facet optical pulses with full-width half-maximum down to 3.7 ps. Single-section quantum-dot mode-locked lasers show 0.8 ps broad optical pulses after external fiber-based compression. Injection current tuning from 70 to 300 mA leads to 30 MHz frequency tuning.

1.55-μm mode-locked quantum-dot lasers with 300 MHz frequency tuning range

International Nuclear Information System (INIS)

Sadeev, T.; Arsenijević, D.; Bimberg, D.; Franke, D.; Kreissl, J.; Künzel, H.

2015-01-01

Passive mode-locking of two-section quantum-dot mode-locked lasers grown by metalorganic vapor phase epitaxy on InP is reported. 1250-μm long lasers exhibit a wide tuning range of 300 MHz around the fundamental mode-locking frequency of 33.48 GHz. The frequency tuning is achieved by varying the reverse bias of the saturable absorber from 0 to −2.2 V and the gain section current from 90 to 280 mA. 3 dB optical spectra width of 6–7 nm leads to ex-facet optical pulses with full-width half-maximum down to 3.7 ps. Single-section quantum-dot mode-locked lasers show 0.8 ps broad optical pulses after external fiber-based compression. Injection current tuning from 70 to 300 mA leads to 30 MHz frequency tuning

Characterization of Definity™ Ultrasound Contrast Agent at Frequency Range of 5–15 MHz

NARCIS (Netherlands)

Faez, Telli; Goertz, David; de Jong, N.

2011-01-01

The status of vasa vasorum, which can be imaged using ultrasound contrast agents, is an indication for the progression of atherosclerosis. The preferred ultrasound frequency for this purpose is between 5 and 15 MHz. Therefore, it is essential to have knowledge about the acoustic properties of

Design and characteristics of L-C thin films filter at microwave frequency band

Science.gov (United States)

Kim, In-Sung; Min, Bok-Ki; Song, Jae-Sung

2005-12-01

Multifunction corresponding to multimedia age has furthermore required high integration to the devices at microwave band, so more evolution for multi-layer integration like system on chip(SoC) becomes to be necessary. In wireless mobile communication, portable mobile phones grew up to a huge market. Microwave devices have played an important role in the wireless communication systems. One challenge in the implementation of circuit integration is in the design of micro wave band pass filter with thin film MOM capacitor and spiral inductor. In this paper, Cu and TaO thin film with RF sputtering was deposited for inductor and capacitor on the SiO II/Si(100) substrate. MIM capacitor and spiral inductor was fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, an important devices for mobile communication. Based on the high-Q values of passive components, MIM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and was 5 dB for a 900 MHz filter. This paper also discusses a theoretical analysis and practical design to L-C band pass filter.

Time-lens based synchronizer and retimer for 10 Gb/s Ethernet packets with up to ±1MHz frequency offset

DEFF Research Database (Denmark)

Laguardia Areal, Janaina; Hu, Hao; Palushani, Evarist

2010-01-01

We present a time-lens based all-optical 10 Gb/s frame synchronizer and retimer. Our scheme can work with a 4096-bit frame, with frequency offset up to 1MHz, which is demonstrated by experimental results.......We present a time-lens based all-optical 10 Gb/s frame synchronizer and retimer. Our scheme can work with a 4096-bit frame, with frequency offset up to 1MHz, which is demonstrated by experimental results....

Demosaicking Based on Optimization and Projection in Different Frequency Bands

Directory of Open Access Journals (Sweden)

Omer OsamaA

2008-01-01

Full Text Available Abstract A fast and effective iterative demosaicking algorithm is described for reconstructing a full-color image from single-color filter array data. The missing color values are interpolated on the basis of optimization and projection in different frequency bands. A filter bank is used to decompose an initially interpolated image into low-frequency and high-frequency bands. In the low-frequency band, a quadratic cost function is minimized in accordance with the observation that the low-frequency components of chrominance slowly vary within an object region. In the high-frequency bands, the high-frequency components of the unknown values are projected onto the high-frequency components of the known values. Comparison of the proposed algorithm with seven state-of-the-art demosaicking algorithms showed that it outperforms all of them for 20 images on average in terms of objective quality and that it is competitive with them from the subjective quality and complexity points of view.

rf measurements and tuning of the 750 MHz radio frequency quadrupole

Science.gov (United States)

Koubek, Benjamin; Grudiev, Alexej; Timmins, Marc

2017-08-01

In the framework of the program on medical applications a compact 750 MHz RFQ has been designed and built to be used as an injector for a hadron therapy linac. This RFQ was designed to accelerate protons to an energy of 5 MeV within only 2 m length. It is divided into four segments and equipped with 32 tuners in total. The length of the RFQ corresponds to 5 λ which is considered to be close to the limit for field adjustment using only piston tuners. Moreover the high frequency, which is about double the frequency of existing RFQs, results in a sensitive structure and requires careful tuning. In this paper we present the tuning algorithm, the tuning procedure and rf measurements of the RFQ.

Low-frequency (0.7-7.4 mHz geomagnetic field fluctuations at high latitude: frequency dependence of the polarization pattern

Directory of Open Access Journals (Sweden)

L. Cafarella

2001-06-01

Full Text Available A statistical analysis of the polarization pattern of low-frequency geomagnetic field fluctuations (0.7-7.4 mHz covering the entire 24-h interval was performed at the Antarctic station Terra Nova Bay (80.0°S geomagnetic latitude throughout 1997 and 1998. The results show that the polarization pattern exhibits a frequency dependence, as can be expected from the frequency dependence of the latitude where the coupling between the magnetospheric compressional mode and the field line resonance takes place. The polarization analysis of single pulsation events shows that wave packets with different polarization sense, depending on frequency, can be simultaneously observed.

HTS dual-band bandpass filters using stub-loaded hair-pin resonators for mobile communication systems

Energy Technology Data Exchange (ETDEWEB)

Sekiya, N., E-mail: nsekiya@yamanashi.ac.jp; Sugiyama, S.

2014-09-15

Highlights: • We have developed a HTS five-pole dual-band bandpass filter using stub-loaded hair-pin resonators. • The proposed dual-band BPF can independently control of the center frequency. • Flexibly adjustment of the bandwidth can be achieved by the H-shaped waveguide. • The proposed BPF is evaluated by simulation and measurement with good agreement. - Abstract: A HTS dual-band bandpass filter is developed to obtain sharp-cut off characteristics for mobile communication systems. The filter is composed of five stub-loaded hair-pin resonators with H-shaped waveguides between them. The main advantage of the proposed filter is to allow independent control of the center frequency of the first and second bands. The bandwidths can be flexibly adjusted using the H-shaped waveguide. An electromagnetic simulator was used to design and analyze the filter, which have a 3.5-GHz center frequency and a 70-MHz (2%) bandwidth for the first band and a 5.0-GHz center frequency and a 100-MHz (2%) bandwidth for the second band. The filter was fabricated using YBa{sub 2}Cu{sub 3}O{sub y} thin film on an Al{sub 2}O{sub 3} substrate. Ground plane was fabricated using Au thin film. The measured frequency responses of the filter tally well with the simulated ones.

High-frequency homogenization of zero frequency stop band photonic and phononic crystals

CERN Document Server

Antonakakis, Tryfon; Guenneau, Sebastien

2013-01-01

We present an accurate methodology for representing the physics of waves, for periodic structures, through effective properties for a replacement bulk medium: This is valid even for media with zero frequency stop-bands and where high frequency phenomena dominate. Since the work of Lord Rayleigh in 1892, low frequency (or quasi-static) behaviour has been neatly encapsulated in effective anisotropic media. However such classical homogenization theories break down in the high-frequency or stop band regime. Higher frequency phenomena are of significant importance in photonics (transverse magnetic waves propagating in infinite conducting parallel fibers), phononics (anti-plane shear waves propagating in isotropic elastic materials with inclusions), and platonics (flexural waves propagating in thin-elastic plates with holes). Fortunately, the recently proposed high-frequency homogenization (HFH) theory is only constrained by the knowledge of standing waves in order to asymptotically reconstruct dispersion curves an...

Ionospheric Coherence Bandwidth Measurements in the Lower VHF Frequency Range

Science.gov (United States)

Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

2015-12-01

The United States Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 820 - 1100 MHz. In this paper, we present simultaneous ionospheric coherence bandwidth and S4 scintillation index measurements in the 32 - 44 MHz frequency range collected during the ESCINT equatorial scintillation experiment. 40-MHz continuous wave (CW) and 32 - 44 MHz swept frequency signals were transmitted simultaneously to the RFProp receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in three separate campaigns during the 2014 and 2015 equinoxes. Results show coherence bandwidths as small as ~ 1 kHz for strong scintillation (S4 > 0.7) and indicate a high degree of ionospheric variability and irregularity on 10-m spatial scales. Spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities are also observed and are dominant at low elevation angles. The results are compared to previous measurements and available scaling laws.

Study and realisation of a high frequency analyzer; Etude et realisation d'un analyseur de signaux a haute frequence

Energy Technology Data Exchange (ETDEWEB)

Bourbigot, J [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

1966-07-01

This device is designed for the amplitude and frequency analysis of electric or electromagnetic signals in the frequency range of 0 to 55 MHz. The frequency spectrum of a preset bandwidth is displayed on the screen of an oscilloscope. Conceived to analyse the electromagnetic oscillations that can be generated in a plasma, its main characteristics are the following: extended bandwidth of analysed frequencies, on both sides of the ion cyclotron frequency in a magnetic field up to 20 kGs; linear amplitude and frequency response; possibility of analysing a narrow band; high sensitivity; analysis repetition rate of 25 per second. The different parts of the analyzer are described after a discussion of the choice of the techniques used in their design. In addition to its present use, the device can be applied to perform all the functions of a commercial spectral analyzer. (author) [French] Cet appareil est destine a l'analyse en frequence et amplitude de signaux electriques ou electromagnetiques dans une gamme de frequences de 0 a 55 MHz. Couple a un oscillographe, il permet de faire apparaitre sur l'ecran, le spectre de frequences dans une gamme choisie. Etudie dans le but d'analyser les oscillations electromagnetiques pouvant apparaitre dans un plasma, ses principales caracteristiques sont les suivantes: une bande etendue de frequences analysees, de part et d'autre de la frequence cyclotronique des ions dans un champ magnetique pouvant atteindre 20 kGs (valeur maximum 55 MHz); une reponse lineaire en amplitude et en frequence; la possibilite d'analyser, une bande restreinte de frequences; une grande sensibilite La frequence d'analyse est de 25 periodes par seconde. Les diverses parties de l'analyseur sont decrites apres l'expose des motifs ayant guide le choix des solutions adoptees pour sa realisation. Les schemas electriques sont egalement presentes. En dehors du but precis qui a motive la realisation de cet appareil, son usage peut s'etendre a toutes les applications

Clamped seismic metamaterials: ultra-low frequency stop bands

International Nuclear Information System (INIS)

Achaoui, Y; Enoch, S; Guenneau, S; Antonakakis, T; Brûlé, S; Craster, R V

2017-01-01

The regularity of earthquakes, their destructive power, and the nuisance of ground vibration in urban environments, all motivate designs of defence structures to lessen the impact of seismic and ground vibration waves on buildings. Low frequency waves, in the range 1–10 Hz for earthquakes and up to a few tens of Hz for vibrations generated by human activities, cause a large amount of damage, or inconvenience; depending on the geological conditions they can travel considerable distances and may match the resonant fundamental frequency of buildings. The ultimate aim of any seismic metamaterial, or any other seismic shield, is to protect over this entire range of frequencies; the long wavelengths involved, and low frequency, have meant this has been unachievable to date. Notably this is scalable and the effects also hold for smaller devices in ultrasonics. There are three approaches to obtaining shielding effects: bragg scattering, locally resonant sub-wavelength inclusions and zero-frequency stop-band media. The former two have been explored, but the latter has not and is examined here. Elastic flexural waves, applicable in the mechanical vibrations of thin elastic plates, can be designed to have a broad zero-frequency stop-band using a periodic array of very small clamped circles. Inspired by this experimental and theoretical observation, all be it in a situation far removed from seismic waves, we demonstrate that it is possible to achieve elastic surface (Rayleigh) wave reflectors at very large wavelengths in structured soils modelled as a fully elastic layer periodically clamped to bedrock. We identify zero frequency stop-bands that only exist in the limit of columns of concrete clamped at their base to the bedrock. In a realistic configuration of a sedimentary basin 15 m deep we observe a zero frequency stop-band covering a broad frequency range of 0–30 Hz. (paper)

47 CFR 90.677 - Reconfiguration of the 806-824/851-869 MHz band in order to separate cellular systems from non...

Science.gov (United States)

2010-10-01

... in order to separate cellular systems from non-cellular systems. 90.677 Section 90.677... of the 806-824/851-869 MHz band in order to separate cellular systems from non-cellular systems. In...-density cellular systems from non-cellular systems, Nextel Communications, Inc. (Nextel) may relocate...

Providing primary standard calibrations beyond 20 MHz

International Nuclear Information System (INIS)

Bickley, C J; Zeqiri, B; Robinson, S P

2004-01-01

The number of applications of medical ultrasound utilising frequencies in excess of 20 MHz has shown a consistent increase over recent years. Coupled with the commercial availability of wide-bandwidth hydrophones whose response extends beyond 40 MHz, this has driven a growing need to develop hydrophone calibration techniques at elevated frequencies. The current National Physical Laboratory primary standard method of calibrating hydrophones is based on an optical interferometer. This has been in operation for around 20 years and provides traceability over the frequency range of 0.3 to 20 MHz. More recently, calibrations carried out using the interferometer have been extended to 60 MHz, although the uncertainties associated with these calibrations are poor, being in excess of ±20% at high frequencies. Major contributions to the degraded calibration uncertainties arise from poor signal-to-noise at higher frequencies, the frequency response of the photodiodes used and the noise floor of the instrument. To improve the uncertainty of hydrophone calibrations above 20 MHz, it has been necessary to build and commission a new interferometer. Important features of the new primary standard are its use of a higher power laser to improve the signal-to-noise ratio, along with photodiodes whose greater bandwidth to improve the overall frequency response. This paper describes the design of key aspects of the new interferometer. It also presents some initial results of the performance assessment, including a detailed comparison of calibrations of NPL reference membrane hydrophones, undertaken using old and new interferometers for calibration up to 40 MHz

New fabrication of high-frequency (100-MHz) ultrasound PZT film kerfless linear array.

Science.gov (United States)

Zhu, Benpeng; Chan, Ngai Yui; Dai, Jiyan; Shung, K Kirk; Takeuchi, Shinichi; Zhou, Qifa

2013-04-01

The paper describes the design, fabrication, and measurements of a high-frequency ultrasound kerfless linear array prepared from hydrothermal lead zirconate titanate (PZT) thick film. The 15-μm hydrothermal PZT thick film with an area of 1 × 1 cm, obtained through a self-separation process from Ti substrate, was used to fabricate a 32-element 100-MHz kerfless linear array with photolithography. The bandwidth at -6 dB without matching layer, insertion loss around center frequency, and crosstalk between adjacent elements were measured to be 39%, -30 dB, and -15 dB, respectively.

Narrow-band radio flares from red dwarf stars

Science.gov (United States)

White, Stephen M.; Kundu, Mukul R.; Jackson, Peter D.

1986-01-01

VLA observations of narrow-band behavior in 20 cm flares from two red dwarf stars, L726 - 8A and AD Leo, are reported. The flare on L726 - 8A was observed at 1415 and 1515 MHz; the flux and the evolution differed significantly at the two frequencies. The flare on AD Leo lasted for 2 hr at 1415 MHz but did not appear at 1515 MHz. The AD Leo flare appears to rule out a source drifting through the stellar corona and is unlikely to be due to plasma emission. In the cyclotron maser model the narrow-band behavior reflects the range of magnetic fields present within the source. The apparent constancy of this field for 2 hr is difficult to understand if magnetic reconnection is the source of energy for the flare. The consistent polarization exhibited by red dwarf flares at 20 cm may be related to stellar activity cycles, and changes in this polarization will permit measuring the length of these cycles.

Performance of high-temperature superconducting band-pass filters with high selectivity for base transceiver applications of digital cellular communication systems

Science.gov (United States)

Kwak, J. S.; Lee, J. H.; Kim, C. O.; Hong, J. P.; Han, S. K.; Char, K.

2002-07-01

Highly selective high-temperature superconducting band-pass filters based on spiral meander line structures have been developed for base transceiver station applications of digital cellular communication systems. The filter comprised 12-pole microstrip line resonators with a circuit size of 0.5 × 17 × 41 mm3. The filter was designed to have a bandwidth of 25 MHz at a centre frequency of 834 MHz. Particularly, the physical size of each resonator was chosen not only to reduce far-field radiation, but also to have reasonable tunability in the filter. Device characteristics exhibited a low insertion loss of 0.4 dB with a 0.2 dB ripple and a return loss better than 10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB at about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge.

Performance of high-temperature superconducting band-pass filters with high selectivity for base transceiver applications of digital cellular communication systems

Energy Technology Data Exchange (ETDEWEB)

Kwak, J.S.; Lee, J.H.; Kim, C.O.; Hong, J.P. [Department of Physics, Hanyang University, Seoul (Korea, Republic of); Han, S.K.; Char, K. [RFtron Inc., Seoul (Korea, Republic of)

2002-07-01

Highly selective high-temperature superconducting band-pass filters based on spiral meander line structures have been developed for base transceiver station applications of digital cellular communication systems. The filter comprised 12-pole microstrip line resonators with a circuit size of 0.5x17x41 mm{sup 3}. The filter was designed to have a bandwidth of 25 MHz at a centre frequency of 834 MHz. Particularly, the physical size of each resonator was chosen not only to reduce far-field radiation, but also to have reasonable tunability in the filter. Device characteristics exhibited a low insertion loss of 0.4 dB with a 0.2 dB ripple and a return loss better than 10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB at about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge. (author)

Performance of high-temperature superconducting band-pass filters with high selectivity for base transceiver applications of digital cellular communication systems

International Nuclear Information System (INIS)

Kwak, J.S.; Lee, J.H.; Kim, C.O.; Hong, J.P.; Han, S.K.; Char, K.

2002-01-01

Highly selective high-temperature superconducting band-pass filters based on spiral meander line structures have been developed for base transceiver station applications of digital cellular communication systems. The filter comprised 12-pole microstrip line resonators with a circuit size of 0.5x17x41 mm 3 . The filter was designed to have a bandwidth of 25 MHz at a centre frequency of 834 MHz. Particularly, the physical size of each resonator was chosen not only to reduce far-field radiation, but also to have reasonable tunability in the filter. Device characteristics exhibited a low insertion loss of 0.4 dB with a 0.2 dB ripple and a return loss better than 10 dB in the pass-band at 65 K. The out-of-band signals were attenuated better than 60 dB at about 3.5 MHz from the lower band edge, and 3.8 MHz from the higher band edge. (author)

47 CFR 25.221 - Blanket Licensing provisions for Earth Stations on Vessels (ESVs) receiving in the 3700-4200 MHz...

Science.gov (United States)

2010-10-01

... the 5925-6425 MHz (Earth-to-space) frequency band, operating with Geostationary Satellite Orbit (GSO) Satellites in the Fixed-Satellite Service. 25.221 Section 25.221 Telecommunication FEDERAL COMMUNICATIONS... 47 Telecommunication 2 2010-10-01 2010-10-01 false Blanket Licensing provisions for Earth Stations...

Electron density modulation in a pulsed dual-frequency (2/13.56 MHz) dual-antenna inductively coupled plasma discharge

Energy Technology Data Exchange (ETDEWEB)

Sirse, Nishant, E-mail: nishant.sirse@dcu.ie [Plasma Research Laboratory, School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Mishra, Anurag [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Yeom, Geun Y. [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, South Korea and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, Gyeunggi-do 440-746 (Korea, Republic of); Ellingboe, Albert R. [Plasma Research Laboratory, School of Physical Sciences, Dublin City University, Dublin 9, Ireland and Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

2016-09-15

The electron density, n{sub e}, modulation is measured experimentally using a resonance hairpin probe in a pulsed, dual-frequency (2/13.56 MHz), dual-antenna, inductively coupled plasma discharge produced in argon-C{sub 4}F{sub 8} (90–10) gas mixtures. The 2 MHz power is pulsed at a frequency of 1 kHz, whereas 13.56 MHz power is applied in continuous wave mode. The discharge is operated at a range of conditions covering 3–50 mTorr, 100–600 W 13.56 MHz power level, 300–600 W 2 MHz peak power level, and duty ratio of 10%–90%. The experimental results reveal that the quasisteady state n{sub e} is greatly affected by the 2 MHz power levels and slightly affected by 13.56 MHz power levels. It is observed that the electron density increases by a factor of 2–2.5 on increasing 2 MHz power level from 300 to 600 W, whereas n{sub e} increases by only ∼20% for 13.56 MHz power levels of 100–600 W. The rise time and decay time constant of n{sub e} monotonically decrease with an increase in either 2 or 13.56 MHz power level. This effect is stronger at low values of 2 MHz power level. For all the operating conditions, it is observed that the n{sub e} overshoots at the beginning of the on-phase before relaxing to a quasisteady state value. The relative overshoot density (in percent) depends on 2 and 13.56 MHz power levels. On increasing gas pressure, the n{sub e} at first increases, reaching to a maximum value, and then decreases with a further increase in gas pressure. The decay time constant of n{sub e} increases monotonically with pressure, increasing rapidly up to 10 mTorr gas pressure and at a slower rate of rise to 50 mTorr. At a fixed 2/13.56 MHz power level and 10 mTorr gas pressure, the quasisteady state n{sub e} shows maximum for 30%–40% duty ratio and decreases with a further increase in duty ratio.

MHz gravitational waves from short-term anisotropic inflation

International Nuclear Information System (INIS)

Ito, Asuka; Soda, Jiro

2016-01-01

We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around 10 −26 ∼10 −27 are copiously produced in high-frequency bands 10 MHz∼100 MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

Low Frequency (11 mHz) Oscillations in H1743-322: A New Class of Black Hole QPOs?

Science.gov (United States)

Altamirano, D.; Strohmayer, T.

2012-01-01

We report the discovery of quasi-periodic oscillations (QPO) at approx 11 mHz in two RXTE observations and one Chandra observation of the black hole candidate HI743-322. The QPO is observed only at the beginning of the 2010 and 2011 outbursts at similar hard color and intensity, suggestive of an accretion state dependence for the QPO. Although its frequency appears to be correlated with Xray intensity on timescales of a day, in successive outbursts eight months apart we measure a QPO frequency that differs by less than approximately equals 0.0015 Hz while the intensity had changed significantly. We show that this 11 mHz QPO is different from the so-called Type-C QPOs seen in black holes and that the mechanisms that produce the two flavors of variability are most probably independent. We compare the 11 mHz QPO with other variability phenomena seen in accreting black holes and neutron stars and conclude that although at 1-2 orders of magnitude lower in frequency, they best resemble the so-called "1 Hz" QPOs seen in dipping neutron star systems. If confirmed, H1743-322 is the first black hole showing this type of variability. Given the unusual characteristics and the hard-state dependence of the 11 mHz QPO, we speculate that these oscillations might instead be related to the radio jets observed in HI743-322. It remains unexplained, however, why similar QPOs have not yet been identified in other black holes and why they have only been seen in the last two outbursts of HI743-322.

High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz

International Nuclear Information System (INIS)

Huang, Chih-Chung

2010-01-01

There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r 2 ) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm -1 at 30 MHz to 0.47 Nepers mm -1 at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was maximal around a

BLAZAR SPECTRAL PROPERTIES AT 74 MHz

Energy Technology Data Exchange (ETDEWEB)

Massaro, F.; Funk, S. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Giroletti, M. [INAF Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Paggi, A.; D' Abrusco, R. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy)

2013-10-01

Blazars are the most extreme class of active galactic nuclei. Despite a previous investigation at 102 MHz for a small sample of BL Lac objects and our recent analysis of blazars detected in the Westerbork Northern Sky Survey, a systematic study of the blazar spectral properties at frequencies below 100 MHz has been never carried out. In this paper, we present the first analysis of the radio spectral behavior of blazars based on the recent Very Large Array Low-frequency Sky Survey (VLSS) at 74 MHz. We search for blazar counterparts in the VLSS catalog, confirming that they are detected at 74 MHz. We then show that blazars present radio-flat spectra (i.e., radio spectral indices of ∼0.5) when evaluated, which also about an order of magnitude in frequency lower than previous analyses. Finally, we discuss the implications of our findings in the context of the blazars-radio galaxies connection since the low-frequency radio data provide a new diagnostic tool to verify the expectations of the unification scenario for radio-loud active galaxies.

A novel method for determining calibration and behavior of PVDF ultrasonic hydrophone probes in the frequency range up to 100 MHz.

Science.gov (United States)

Bleeker, H J; Lewin, P A

2000-01-01

A new calibration technique for PVDF ultrasonic hydrophone probes is described. Current implementation of the technique allows determination of hydrophone frequency response between 2 and 100 MHz and is based on the comparison of theoretically predicted and experimentally determined pressure-time waveforms produced by a focused, circular source. The simulation model was derived from the time domain algorithm that solves the non linear KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation describing acoustic wave propagation. The calibration technique data were experimentally verified using independent calibration procedures in the frequency range from 2 to 40 MHz using a combined time delay spectrometry and reciprocity approach or calibration data provided by the National Physical Laboratory (NPL), UK. The results of verification indicated good agreement between the results obtained using KZK and the above-mentioned independent calibration techniques from 2 to 40 MHz, with the maximum discrepancy of 18% at 30 MHz. The frequency responses obtained using different hydrophone designs, including several membrane and needle probes, are presented, and it is shown that the technique developed provides a desirable tool for independent verification of primary calibration techniques such as those based on optical interferometry. Fundamental limitations of the presented calibration method are also examined.

78 FR 28749 - Private Land Mobile Radio Stations Below 800 MHz

Science.gov (United States)

2013-05-16

... these proposals, with the exception of those issues relating to Wireless Medical Telemetry Services... accomplished in the PLMR bands below 800 MHz. A trunked radio system employs technology that can search two or... prohibited by Sec. 1.935). We also take this opportunity to correct the 800 MHz band trunking rules to set...

Low frequency astronomy - the challenge in a crowded RFI environment

NARCIS (Netherlands)

Bentum, Marinus Jan; Boonstra, Albert Jan

2011-01-01

Low frequency radio astronomy is a hot topic at the moment. Many large arrays of antennas are built to facilitate the astronomical research on low frequencies. Building an instrument for the frequency band below 30 MHz on Earth will run into some problems. One of the issues is the instable and

Two efficient methods for measuring hydrophone frequency response in the 100 kHz to 2 MHz range

International Nuclear Information System (INIS)

Harris, G R; Maruvada, S; Gammell, P M

2004-01-01

As new medical applications of ultrasound emerge with operating frequencies in the hundreds of kilohertz to low megahertz region, it becomes more important to have convenient calibration methods for hydrophones in this frequency range. Furthermore, short diagnostic ultrasound pulses affected by finite amplitude distortion require that the hydrophone frequency response be known well below the center frequency. National standards laboratories can provide accurate calibration data at these frequencies, but the two methods now employed, laser interferometry and three-transducer reciprocity, are both single-frequency techniques, and they can be time-consuming procedures. Therefore, two efficient methods for generating a wideband acoustic pressure spectrum have been implemented to cover this frequency range. In one method a high-voltage pulse generator was used to excite a thick piezoelectric ceramic disk, producing a plane-wave acoustic pressure transient <1 μs in duration with peak amplitude of about 40 kPa. In the other technique, time delay spectrometry (TDS), a purpose-built 1-3 piezoelectric composite source transducer weakly focused at 20 cm was swept over the 0-2 MHz range. Its transmitting voltage response at 1 MHz was 11 kPa/V. The broadband pulse technique has the advantage of being simpler to implement, but TDS has a much greater signal-to-noise ratio because of the frequency-swept narrowband filter employed

Bandwidth-Efficient Communication through 225 MHz Ka-band Relay Satellite Channel

Science.gov (United States)

Downey, Joseph; Downey, James; Reinhart, Richard C.; Evans, Michael Alan; Mortensen, Dale John

2016-01-01

The communications and navigation space infrastructure of the National Aeronautics and Space Administration (NASA) consists of a constellation of relay satellites (called Tracking and Data Relay Satellites (TDRS)) and a global set of ground stations to receive and deliver data to researchers around the world from mission spacecraft throughout the solar system. Planning is underway to enhance and transform the infrastructure over the coming decade. Key to the upgrade will be the simultaneous and efficient use of relay transponders to minimize cost and operations while supporting science and exploration spacecraft. Efficient use of transponders necessitates bandwidth efficient communications to best use and maximize data throughput within the allocated spectrum. Experiments conducted with NASA's Space Communication and Navigation (SCaN) Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques, such as bandwidth-efficient modulations, in an operational flight system. Demonstrations of these new techniques in realistic flight conditions provides critical experience and reduces the risk of using these techniques in future missions. Efficient use of spectrum is enabled by using high-order modulations coupled with efficient forward error correction codes. This paper presents a high-rate, bandwidth-efficient waveform operating over the 225 MHz Ka-band service of the TDRS System (TDRSS). The testing explores the application of Gaussian Minimum Shift Keying (GMSK), 248-phase shift keying (PSK) and 1632- amplitude PSK (APSK) providing over three bits-per-second-per-Hertz (3 bsHz) modulation combined with various LDPC encoding rates to maximize throughput. With a symbol rate of 200 Mbaud, coded data rates of 1000 Mbps were tested in the laboratory and up to 800 Mbps over the TDRS 225 MHz channel. This paper will present on the high-rate waveform design, channel characteristics, performance results, compensation

47 CFR 90.531 - Band plan.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 763-775 MHz and 793... and portables subject to Commission-approved regional planning committee regional plans. Transmitter...

Electromagnetic design of a β=0.9, 650 MHz elliptic superconducting radio frequency cavity

International Nuclear Information System (INIS)

Jana, Arup Ratan; Kumar, V.

2011-01-01

We have recently performed two-dimensional (2D) electromagnetic design studies of a β=0.9, 650 MHz, elliptic superconducting radio frequency (SCRF) cavity using electromagnetic field solver code SUPERFISH. We have evolved the design starting from the design parameters of β=1, 1300 MHz, TESLA design SCRF cavity and then scaled it for the β=0.9 and 650 MHz case. The design has been optimized for minimizing the SCRF cavity power loss. One of the important parameters in the design of such elliptic SCRF cavities is the wall angle, which is defined as the vertical angle made by the common tangent to the iris and equator ellipses. Generally, there is a constraint on the minimum value of the wall angle, which is decided by the mechanical considerations, ease of chemical cleaning etc. In our optimization studies, we have first explored the case when there is no such constraint on wall angle. We find that from the point of view of low cavity power dissipation, the optimized design has a re-entrant geometry, where the wall angle is negative. We then perform design optimization, keeping the constraint that the wall angle should be greater than 5 degree. Keeping this constraint, we find that our optimized design parameters for the single cell match closely with the design parameters reported for Project-X. We discuss the results of 2D electromagnetic field calculations for this design using SUPERFISH. In the next, we have performed the design studies of the multi-cell β=0.9, 650 MHz, elliptic SCRF cavity. The design parameters of end-cells are optimized such that the frequency of the end-cell is matched to that of mid-cells. We have studied all the normal modes for the multi-cell cavity. The frequency of different normal modes is also calculated using a finite element code ANSYS and results are compared with those obtained using SUPERFISH. The field flatness, which is an important design criterion, is also studied. For multi-cell cavity, another important aspect is the cell

Co-channel and Adjacent Channel Interference Measurement of UMTS and GSM/EDGE Systems in 900 MHz Radio Band

Directory of Open Access Journals (Sweden)

S. Hanus

2008-09-01

Full Text Available This paper is concerned with inter-system and intra-system interference measurements of 2.5G and 3G mobile communication systems. The both systems UMTS and GSM/EDGE are assumed to operate in a common radio band of 900 MHz. The main system parameters are briefly introduced as well as the measurement scenario. Several simulations and key measurements were performed. Important results are described and commented along with a graphical representation, namely bit error ratio (BER dependence on carrier to noise ratio (CNR in the presence of additive white Gaussian noise (AWGN, the measurement of adjacent channel interference ratio of each system, the coexistence of both systems in same band and the impact of a carrier offset on BER.

rf measurements and tuning of the 750 MHz radio frequency quadrupole

Directory of Open Access Journals (Sweden)

Benjamin Koubek

2017-08-01

Full Text Available In the framework of the program on medical applications a compact 750 MHz RFQ has been designed and built to be used as an injector for a hadron therapy linac. This RFQ was designed to accelerate protons to an energy of 5 MeV within only 2 m length. It is divided into four segments and equipped with 32 tuners in total. The length of the RFQ corresponds to 5λ which is considered to be close to the limit for field adjustment using only piston tuners. Moreover the high frequency, which is about double the frequency of existing RFQs, results in a sensitive structure and requires careful tuning. In this paper we present the tuning algorithm, the tuning procedure and rf measurements of the RFQ.

Implementation of body area networks based on MICS/WMTS medical bands for healthcare systems.

Science.gov (United States)

Yuce, Mehmet R; Ho, Chee Keong

2008-01-01

A multi-hoping sensor network system has been implemented to monitor physiological parameters from multiple patient bodies by means of medical communication standards MICS (Medical Implant Communication Service) and WMTS (Wireless Medical Telemetry Service). Unlike the other medical sensor networks (they usually use 2.4 GHz ISM band), we used the two medical standards occupying the frequency bands that are mainly assigned to medical applications. The prototype system uses the MICS band (402-405 MHz) between the sensor nodes and a remote central control unit (CCU). And WMTS frequencies (608-614MHz) are used between the CCUs and the remote base stations allowing for a much larger range acting as an intermediate node. The sensor nodes in the prototype can measure up to four body signals (i.e. 4-channel) where one is dedicated to a continuous physiological signal such as ECC/EEG. The system includes firmware and software designs that can provide a long distance data transfer through the internet or a mobile network.

Research on low-frequency band gap property of a hybrid phononic crystal

Science.gov (United States)

Dong, Yake; Yao, Hong; Du, Jun; Zhao, Jingbo; Chao, Ding; Wang, Benchi

2018-05-01

A hybrid phononic crystal has been investigated. The characteristic frequency of XY mode, transmission loss and displacement vector have been calculated by the finite element method. There are Bragg scattering band gap and local resonance band gap in the band structures. We studied the influence factors of band gap. There are many flat bands in the eigenfrequencies curve. There are many flat bands in the curve. The band gap covers a large range in low frequency. The band gaps cover more than 95% below 3000 Hz.

77 FR 22720 - Service Rules for Advanced Wireless Services in the 2000-2020 MHz and 2180-2200 MHz Bands, etc.

Science.gov (United States)

2012-04-17

... operations in 1930-1995 MHz and uplink operations in 2000-2020 MHz. To address this apparent tension, we seek... includes broadcast auxiliary service (BAS) and cable television service (CARS) operations, as well as...

Narrow-band radio flares from red dwarf stars

Energy Technology Data Exchange (ETDEWEB)

White, S.M.; Kundu, M.R.; Jackson, P.D.

1986-12-01

VLA observations of narrow-band behavior in 20 cm flares from two red dwarf stars, L726 - 8A and AD Leo, are reported. The flare on L726 - 8A was observed at 1415 and 1515 MHz; the flux and the evolution differed significantly at the two frequencies. The flare on AD Leo lasted for 2 hr at 1415 MHz but did not appear at 1515 MHz. The AD Leo flare appears to rule out a source drifting through the stellar corona and is unlikely to be due to plasma emission. In the cyclotron maser model the narrow-band behavior reflects the range of magnetic fields present within the source. The apparent constancy of this field for 2 hr is difficult to understand if magnetic reconnection is the source of energy for the flare. The consistent polarization exhibited by red dwarf flares at 20 cm may be related to stellar activity cycles, and changes in this polarization will permit measuring the length of these cycles. 22 references.

Exposure assessment in front of a multi-band base station antenna.

Science.gov (United States)

Kos, Bor; Valič, Blaž; Kotnik, Tadej; Gajšek, Peter

2011-04-01

This study investigates occupational exposure to electromagnetic fields in front of a multi-band base station antenna for mobile communications at 900, 1800, and 2100 MHz. Finite-difference time-domain method was used to first validate the antenna model against measurement results published in the literature and then investigate the specific absorption rate (SAR) in two heterogeneous, anatomically correct human models (Virtual Family male and female) at distances from 10 to 1000 mm. Special attention was given to simultaneous exposure to fields of three different frequencies, their interaction and the additivity of SAR resulting from each frequency. The results show that the highest frequency--2100 MHz--results in the highest spatial-peak SAR averaged over 10 g of tissue, while the whole-body SAR is similar at all three frequencies. At distances > 200 mm from the antenna, the whole-body SAR is a more limiting factor for compliance to exposure guidelines, while at shorter distances the spatial-peak SAR may be more limiting. For the evaluation of combined exposure, a simple summation of spatial-peak SAR maxima at each frequency gives a good estimation for combined exposure, which was also found to depend on the distribution of transmitting power between the different frequency bands. Copyright © 2010 Wiley-Liss, Inc.

Simply folded band chaos in a VHF microstrip oscillator

Energy Technology Data Exchange (ETDEWEB)

Blakely, Jonathan N. [US Army Research, Development, and Engineering Command, AMSRD-AMR-WS-ST, Redstone Arsenal, AL 35898 (United States)]. E-mail: jonathan.blakely@us.army.mil; Holder, J. Darryl [US Army Research, Development, and Engineering Command, AMSRD-AMR-WS-ST, Redstone Arsenal, AL 35898 (United States); Corron, Ned J. [US Army Research, Development, and Engineering Command, AMSRD-AMR-WS-ST, Redstone Arsenal, AL 35898 (United States); Pethel, Shawn D. [US Army Research, Development, and Engineering Command, AMSRD-AMR-WS-ST, Redstone Arsenal, AL 35898 (United States)

2005-10-10

We present experimental observations of a microstrip circuit that produces Roessler-like chaos with center frequency of 175 MHz. A simply folded band chaotic attractor is created through a period doubling route. The circuit provides an experimental realization of a chaotic neutral delay differential equation, a largely unexplored type of nonlinear dynamical system.

Dual Band Parasitic Element Patch Antenna for LTE/WLAN Applications

Directory of Open Access Journals (Sweden)

BAG Biplab

2017-05-01

Full Text Available In this paper, a single layer coaxial fed dual band slotted microstrip antenna is proposed. The proposed antenna consists of two direct couple parasitic elements and L-shape slots on the main resonating element. Two resonant modes are excited and it covers 4G LTE and WLAN middle band. The -10dB impedance bandwidth for resonant frequency of 2.35GHz and 5.28GHz are 140MHz (2.25-2.39GHz and 570MHz (5.18-5.75GHz, respectively. The measured VSWR at 2.35GHz is 1.27 and at 5.28GHz is 1.41. The proposed antenna is simple in design and compact in size. The simulated and measured results are in good agreement.

Geometric optimization of the 56 MHz SRF cavity and its frequency table

International Nuclear Information System (INIS)

Chang, X.; Ben-Zvi, I.

2008-01-01

It is essential to know the frequency of a Superconducting Radio Frequency (SRF) cavity at its 'just being fabricated' stage because frequency is the key parameter in constructing the cavity. In this paper, we report our work on assessing it. We can estimate the frequency change from stage to stage theoretically and/or by simulation. At the operating stage, the frequency can be calculated accurately, and, from this value, we obtain the frequencies at other stages. They are listed in a table that serves to check the processes from stage to stage. Equally important is optimizing the geometric shape of the SRF cavity so that the peak electric-field and peak magnetic-field are as low as possible. It is particularly desirable in the 56MHz SRF cavity of RHIC to maximize the frequency sensitivity of the slow tuner. After undertaking such optimization, our resultant peak electric-field is only 44.1MV/m, and the peak magnetic-field is 1049G at 2.5MV of voltage across the cavity gap. To quench superconductivity in an SRF cavity, it is reported that the limit of the peak magnetic-field is 1800G (1), and that of the peak electric-field is more than l00MV/m for a SRF cavity (2). Our simulations employed the codes Superfish and Microwave Studio

The Daily 110 MHZ Sky Survey (bsa Fian): On-Line Database, Science Aims and First Results of Data Processing

Science.gov (United States)

Samodurov, V. A.; Rodin, A. E.; Kitaeva, M. A.; Isaev, E. A.; Dumsky, D. V.; Churakov, D. D.; Manzyuk, M. O.

From 2012 on radio telescope BSA FIAN multi beams diagram was started. It capable at July 2014 daily observing by 96 beams in declination -8 .. 42 degrees in the frequency band 109-111.5 MHz. The number of frequency bands are from 6 to 32, the time constant are from 0.1 to 0.0125 sec. In receiving mode with 32 band (plus one common band) with a time constant of 12.5 ms (80 times per second) respectively produced 33x96x80 four byte real and so daily we produced 87.5 Gbt (yearly to 32 Tbt). These data are enormous opportunities for both short and long-term monitoring of various classes of radio sources (including radio transients) and for space weather and the Earth's ionosphere monitoring, for search for different classes of radio sources, etc. The base aims of our work are: a) to obtain new scientific data on different classes of discrete radio sources, the construction of physical models and their evolution - obtained on the basis of the clock continuous digital sky radio monitoring at frequency 109-111.5 MHz and cross-analysis of data from third-party reviews on other frequencies; c) launch the streaming data on various types of high-performance computing systems, including to create a public system of distributed computing for thousands of users on the basis of BOINC technology. The BOINC client for astronomical data from the monitoring survey of the big part of entire sky almost have not analogies. We have some first science results (new pulsars, and some new type of radiosources).

Asymmetric acoustic transmission in multiple frequency bands

Energy Technology Data Exchange (ETDEWEB)

Sun, Hong-xiang, E-mail: jsdxshx@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhang, Shu-yi [Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

2015-11-23

We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices.

Asymmetric acoustic transmission in multiple frequency bands

International Nuclear Information System (INIS)

Sun, Hong-xiang; Yuan, Shou-qi; Zhang, Shu-yi

2015-01-01

We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices

An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

Directory of Open Access Journals (Sweden)

Vida Zaroushani

2015-06-01

Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

Test results of the AGS Booster low frequency RF system

International Nuclear Information System (INIS)

Sanders, R.T.; Cameron, P.; Damm, R.; Dunbar, A.; Goldman, M.; Kasha, D.; McNerney, A.; Meth, M.; Ratti, A.; Spitz, R.

1993-01-01

The Band II RF system was originally built to support the Booster operations during the acceleration of heavy ions. Designed to sweep from 0.6 to 2.5 MHz, it was build and successfully tested over a much broader range reaching 4 MHz. Voltages up to more than 20 kV were reached over the design frequency range. The system consists of two stations, each of which is made of one single gap cavity directly driven by a grounded cathode push pull power amplifier. The low Q high permeability ferrites needed in the coaxial cavity in order to reach the lower end of the band make tuning extremely easy. Both systems were thoroughly tested both at single frequencies and on a sweep and are now installed in the ring, ready for operations. Static measurements showed no high-loss effects. The Band 11 system has been fully described in a previous paper; presented here are the results of the ''bench'' tests that lead to important performance improvements

Mid-frequency Band Dynamics of Large Space Structures

Science.gov (United States)

Coppolino, Robert N.; Adams, Douglas S.

2004-01-01

High and low intensity dynamic environments experienced by a spacecraft during launch and on-orbit operations, respectively, induce structural loads and motions, which are difficult to reliably predict. Structural dynamics in low- and mid-frequency bands are sensitive to component interface uncertainty and non-linearity as evidenced in laboratory testing and flight operations. Analytical tools for prediction of linear system response are not necessarily adequate for reliable prediction of mid-frequency band dynamics and analysis of measured laboratory and flight data. A new MATLAB toolbox, designed to address the key challenges of mid-frequency band dynamics, is introduced in this paper. Finite-element models of major subassemblies are defined following rational frequency-wavelength guidelines. For computational efficiency, these subassemblies are described as linear, component mode models. The complete structural system model is composed of component mode subassemblies and linear or non-linear joint descriptions. Computation and display of structural dynamic responses are accomplished employing well-established, stable numerical methods, modern signal processing procedures and descriptive graphical tools. Parametric sensitivity and Monte-Carlo based system identification tools are used to reconcile models with experimental data and investigate the effects of uncertainties. Models and dynamic responses are exported for employment in applications, such as detailed structural integrity and mechanical-optical-control performance analyses.

Radiation from ingested wireless devices in bio-medical telemetry bands

OpenAIRE

Chirwa, L.C.; Roy, S.; Cumming, D.R.S.

2003-01-01

The performance of wireless devices, using electrically small antennae, in the human intestine is investigated using the finite difference time domain method in recommended biomedical device telemetry bands. The radiation field intensity was found to depend on position but more strongly on frequency, with a transmission peak at 650 MHz.

L-Band RFI in Japan

Science.gov (United States)

Soldo, Yan; de Matthaeis, Paolo; Le Vine, David M.

2016-01-01

In recent years, three instruments have been launched into orbit with the aim of producing global maps of sea surface salinity and soil moisture using the 1400-1427 MHz band: SMOS, Aquarius and SMAP. Although this frequency band is allocated to passive measurements only, RFI (Radio-Frequency Interference) is present in the data of all three missions. On a global scale, the three sensors have observed approximately the same distribution of RFI. Japan is an important exception that has implications for the design of RFI detection algorithms. RFI in Japan is caused by a large number of emitters belonging to the same system (TV receivers) and for this reason some traditional RFI detection strategies detect little to no RFI over Japan. The study of this case has led to an improvement of the approach to detect RFI in Aquarius data.

Beam paths of flexural Lamb waves at high frequency in the first band within phononic crystal-based acoustic lenses

Directory of Open Access Journals (Sweden)

J. Zhao

2014-12-01

Full Text Available This work deals with an analytical and numerical study of the focusing of the lowest order anti-symmetric Lamb wave in gradient index phononic crystals. Computing the ray trajectories of the elastic beam allowed us to analyze the lateral dimensions and shape of the focus, either in the inner or behind the phononic crystal-based acoustic lenses, for frequencies within a broad range in the first band. We analyzed and discussed the focusing behaviors inside the acoustic lenses where the focalization at sub-wavelength scale was achieved. The focalization behind the gradient index phononic crystal is shown to be efficient as well: we report on FMHM = 0.63λ at 11MHz.

47 CFR 25.253 - Special requirements for ancillary terrestrial components operating in the 1626.5-1660.5 MHz/1525...

Science.gov (United States)

2010-10-01

... commercial mobile radio service (CMRS) base stations that make use of Global Positioning System (GPS) time... toward the physical horizon (not to include man-made structures) of 26.9-10*log (number of carriers) dBW... 1541.5-1547.5 MHz frequency band; (4) Exceed an EIRP toward the physical horizon (not to include man...

Frequency sensitive moment tensor inversion for light to moderate magnitude earthquakes in eastern Africa

Science.gov (United States)

Barth, A.; Wenzel, F.; Giardini, D.

2007-08-01

We provide a procedure for the routine determination of moment tensors from earthquakes with magnitudes as low as M W 4.4 using data recorded by only a few permanent seismic stations at regional to teleseismic distances. Waveforms are inverted for automatically determined frequency pass-bands that depend on source-receiver locations as well as the earthquake magnitude. Inversion results are stable against small variations in the frequency band and provide low data variances, i.e., a good fit between observed and modelled waveform traces. The total frequency band used for our procedure ranges from 10 mHz to 29 mHz (periods of 35 s to 100 s). This enables us to determine focal mechanisms for earthquakes that were not derived previously by routine procedures of CMT or other agencies. As a case study, we determine focal mechanism solutions of 38 light to moderate magnitude earthquakes in eastern Africa between 1995 and 2002.

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

Science.gov (United States)

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Temporal evolution of electron density in a low pressure pulsed two-frequency (60 MHz/2 MHz) capacitively coupled plasma discharge

International Nuclear Information System (INIS)

Sirse, N; Ellingboe, A R; Jeon, M H; Yeom, G Y

2014-01-01

Time-resolved electron density, n e , is measured in a low pressure pulsed two-frequency capacitively coupled plasma discharge sustained in Ar and in Ar/CF 4 /O 2 (80 : 10 : 10) gas mixture using a floating resonance hairpin probe. The top electrode is powered by 60 MHz in pulse mode and the bottom electrode is powered by 2 MHz in continuous wave mode. The dependence of time-resolved n e on the low frequency (LF) and high frequency (HF) power levels, operating gas pressure, pulse repetition frequency (PRF) and duty cycle are investigated. It is found that the steady state n e in the long on-phase is greatly influenced by the HF power level and slightly affected by the LF power level in both Ar and Ar/CF 4 /O 2 plasma. The decay time of n e is slow (∼30–90 µs) in the case of Ar plasma and strongly depends on the LF power level, whereas in the case of Ar/CF 4 /O 2 gas mixture it is very fast (∼15 µs) and marginally dependent on LF power level. In Ar plasma the steady state n e is increasing with a rise in operating gas pressure, however, in Ar/CF 4 /O 2 plasma it first increases with gas pressure reaching to the maximum (at 20 mTorr) value and then decreases. The pressure dependence of decay time constant mimics the pressure variation of steady state n e . Furthermore, it is observed that the on-phase electron density is greatly affected by changing the PRF and duty cycle. This effect is more prominent in Ar/CF 4 /O 2 plasma when compared to Ar discharge. In addition, n e is observed to overshoot the steady state densities in the beginning of the on-phase in Ar/CF 4 /O 2 gas mixture, but this effect is either small or absent in the case of Ar plasma. (paper)

An impedance bridge measuring the capacitance ratio in the high frequency range up to 1 MHz

International Nuclear Information System (INIS)

Kim, Dan Bee; Lee, Hyung Kew; Kim, Wan-Seop

2017-01-01

This paper describes a 2-terminal-pair impedance bridge, measuring the capacitance ratio in the high frequency range up to 1 MHz. The bridge was configured with two voltage sources and a phase control unit which enabled the bridge balance by synchronizing the voltage sources with an enhanced phase resolution. Without employing the transformers such as inductive voltage divider, injection and detection transformers, etc, the bridge system is quite simple to set up, and the balance procedure is quick and easy. Using this dual-source coaxial bridge, the 1:1 and 10:1 capacitance ratios were measured with 1 pF–1 nF capacitors in the frequency range from 1 kHz to 1 MHz. The measurement values obtained by the dual-source bridge were then compared with reference values measured using a commercial precision capacitance bridge of AH2700A, the Z -matrix method developed by ourselves, and the 4-terminal-pair coaxial bridge by the Czech Metrological Institute. All the measurements agreed within the reference uncertainty range of an order of 10 −6 –10 −5 , proving the bridge ability as a trustworthy tool for measuring the capacitance ratio in the high frequency range. (paper)

Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

International Nuclear Information System (INIS)

Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

2013-01-01

An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of α mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperature of atmospheric pressure plasma could also be obtained using dual-frequency excitation

M-type barium hexa ferrite magnetic material for anti radar materials at s band frequency

International Nuclear Information System (INIS)

Priyono; Azwar Manaf

2010-01-01

In this paper, preparation and characteristic evaluation of microwave absorber materials of BaFe_1_2_-_2_x Mn_x Ti _xO_1_9 (x = 0,0 - 1,5) compositions are discussed. The absorber material was obtained by a co-substitution of Mn and Ti to Fe in a Barium Hexaferrite (BaO.6Fe_2O_3 ) basic compound through a mechanical alloying process. In this respect, a co-substitution of Mn and Ti ions for Fe was applied to Fe_2O_3 component at a temperature ~ 1,300 °C. The substituted alloy component was further alloyed mechanically with BaCO_3 to form M-Type hexaferrite after the solid state reaction. Identification of X-ray diffraction peaks for the mechanically alloyed materials indicates confidently that a single phase BaFe_1_2_-_x_-_yMn_x Ti_yO_1_9 material was formed. Materials characterization is covering the average grain sizes and absorption of microwaves in the frequency range 1-6 GHz. Absorption with a relatively high coefficient at frequencies ~ 2,000 MHz and ~ 3,500 MHz within the available frequency range was obtained. It is shown that the co-substitution of Mn and Ti ion able to widen the absorption frequency especially in the frequencies of about 3,500 MHz. (author)

Design Investigation of a Laminated Waveguide Fed Multi-Band DRA for Military Applications

Science.gov (United States)

Kumar, Pramod; Dwari, Santanu; Singh, Shailendra; Agrawal, N. K.

2017-12-01

In this paper a laminated waveguide fed DR Antenna is investigated. It can use for moderate power military applications. Cylindrical DRA is excited by two closely spaced asymmetric longitudinal slots on the broad wall of the laminated cavity are responsible for producing three different frequency bands. Parametric study of slots has been done with the help of commercial software ANSOFT HFSS. All the bands have sharp rejection. The final model of the antenna is simulated, fabricated and experimentally measured. Measured results are in quite accordant with design results. SIW feeding structures have small losses, moderate power handling capacity, low costs, compact sizes and can be seamlessly integrated with planar circuits. At all the bands 9.76 GHz, 10.53 GHz and 11.8 GHz resonant frequency, the antenna shows 56 MHz, 160 MHz, and 250 MHz impedance bandwidth (for VSWR<2) with 6 dB,6.2 dB and 6.8 dB gain respectively. Simulated and measured results reveal outstanding performance with a cross-polar level of 29 dB lower than that of the co-polar level at 9.76 GHz, the cross-polar level of 32 dB lower than that of the co-polar level at 10.53, GHz, and similarly cross-polar level of 30 dB lower than that of the co-polar level at 11.8 GHz.

VLITE-Fast: A Real-time, 350 MHz Commensal VLA Survey for Fast Transients

Science.gov (United States)

Kerr, Matthew; Ray, Paul S.; Kassim, Namir E.; Clarke, Tracy; Deneva, Julia; Polisensky, Emil

2018-01-01

The VLITE (VLA Low Band Ionosphere and Transient Experiment; http://vlite.nrao.edu) program operates commensally during all Very Large Array observations, collecting data from 320 to 384 MHz. Recently expanded to include 16 antennas, the large field of view and huge time on sky offer good coverage of the transient, low-frequency sky. We describe the VLITE-Fast system, a GPU-based signal processor capable of detecting short (system, techniques for mitigating interference, and initial results from searches for FRBs.

470‐MHz–698‐MHz IEEE 802.15.4m Compliant RF CMOS Transceiver

Directory of Open Access Journals (Sweden)

Youngho Seo

2018-04-01

Full Text Available This paper proposes an IEEE 802.15.4m compliant TV white‐space orthogonal frequency‐division multiplexing (TVWS‐(OFDM radio frequency (RF transceiver that can be adopted in advanced metering infrastructures, universal remote controllers, smart factories, consumer electronics, and other areas. The proposed TVWS‐OFDM RF transceiver consists of a receiver, a transmitter, a 25% duty‐cycle local oscillator generator, and a delta‐sigma fractional‐N phase‐locked loop. In the TV band from 470 MHz to 698 MHz, the highly linear RF transmitter protects the occupied TV signals, and the high‐Q filtering RF receiver is tolerable to in‐band interferers as strong as −20 dBm at a 3‐MHz offset. The proposed TVWS‐OFDM RF transceiver is fabricated using a 0.13‐μm CMOS process, and consumes 47 mA in the Tx mode and 35 mA in the Rx mode. The fabricated chip shows a Tx average power of 0 dBm with an error‐vector‐magnitude of  3%, and a sensitivity level of −103 dBm with a packet‐error‐rate of 3%. Using the implemented TVWS‐OFDM modules, a public demonstration of electricity metering was successfully carried out.

Alpha band frequency differences between low-trait and high-trait anxious individuals.

Science.gov (United States)

Ward, Richard T; Smith, Shelby L; Kraus, Brian T; Allen, Anna V; Moses, Michael A; Simon-Dack, Stephanie L

2018-01-17

Trait anxiety has been shown to cause significant impairments on attentional tasks. Current research has identified alpha band frequency differences between low-trait and high-trait anxious individuals. Here, we further investigated the underlying alpha band frequency differences between low-trait and high-trait anxious individuals during their resting state and the completion of an inhibition executive functioning task. Using human participants and quantitative electroencephalographic recordings, we measured alpha band frequency in individuals both high and low in trait anxiety during their resting state, and while they completed an Eriksen Flanker Task. Results indicated that high-trait anxious individuals exhibit a desynchronization in alpha band frequency from a resting state to when they complete the Eriksen Flanker Task. This suggests that high-trait anxious individuals maintain fewer attentional resources at rest and must martial resources for task performance as compared with low-trait anxious individuals, who appear to maintain stable cognitive resources between rest and task performance. These findings add to the cognitive neuroscience literature surrounding the role of alpha band frequency in low-trait and high-trait anxious individuals.

Impact of foliage on LoRa 433MHz propagation in tropical environment

Science.gov (United States)

Ahmad, Khairol Amali; Salleh, Mohd Sharil; Segaran, Jivitraa Devi; Hashim, Fakroul Ridzuan

2018-02-01

LoRa is being considered as one of the promising system for Low-Power-Wide-Area-Network (LPWAN) to support the growth of Internet of Things (IoT) applications. Designed to operate in the industrial, scientific and medical (ISM) bands, LoRa had been tested and evaluated mainly in Europe and US in the 868 MHz and 915 MHz modulation bands. Using chirp spread spectrum technology, LoRa is expected to be robust against degredation. This paper provides some early results in the performance of LoRa signal propagation of 433 MHz modulation in tropical foliage environments.

Characteristics of SiO{sub 2} etching with a C{sub 4}F{sub 8}/Ar/CHF{sub 3}/O{sub 2} gas mixture in 60-MHz/2-MHz dual-frequency capacitively coupled plasmas

Energy Technology Data Exchange (ETDEWEB)

Jeon, M. H.; Kang, S. K.; Park, J. Y.; Yeom, G. Y. [Sungkyunkwan University, Suwon (Korea, Republic of)

2011-11-15

Nanoscale SiO{sub 2} contact holes were etched by using C{sub 4}F{sub 8}/CHF{sub 3}/O{sub 2}/Ar gas mixtures in dual frequency capacitively coupled plasmas (DF-CCPs) where a 60-MHz source power was applied to the top electrode while a 2-MHz bias power was applied to the bottom electrode. The initial increase in the CHF{sub 3} gas flow rate at a fixed CHF{sub 3}+O{sub 2} flow rate increased the SiO{sub 2} etch rate as well as SiO{sub 2} etch selectivity over that of the amorphous carbon layer (ACL). When the high-frequency (HF) power was increased both SiO{sub 2} etch rate and the etch selectivity over ACL were increased. For a 300 W/500 W power ratio of 60-MHz HF power/ 2-MHz low-freqeuncy (LF) and a gas mixture of Ar (140 sccm) /C{sub 4}F{sub 8} (30 sccm) /CHF{sub 3} (25 sccm) /O{sub 2} (5 sccm) while maintaining 20 mTorr, an anisotropic etch profile with an SiO{sub 2} etch rate of 3350 A/min and an etch selectivity of higher than 6 over ACL could be obtained.

47 CFR 15.240 - Operation in the band 433.5-434.5 MHz.

Science.gov (United States)

2010-10-01

... within the specified frequency band shall not exceed 11,000 microvolts per meter measured at a distance... exceed 55,000 microvolts per meter measured at a distance of 3 meters. Additionally, devices authorized... locations where the devices are installed to the FCC Office of Engineering and Technology, which shall...

HydroCube mission concept: P-Band signals of opportunity for remote sensing of snow and root zone soil moisture

Science.gov (United States)

Yueh, Simon; Shah, Rashmi; Xu, Xiaolan; Elder, Kelly; Chae, Chun Sik; Margulis, Steve; Liston, Glen; Durand, Michael; Derksen, Chris

2017-09-01

We have developed the HydroCube mission concept with a constellation of small satellites to remotely sense Snow Water Equivalent (SWE) and Root Zone Soil Moisture (RZSM). The HydroCube satellites would operate at sun-synchronous 3- day repeat polar orbits with a spatial resolution of about 1-3 Km. The mission goals would be to improve the estimation of terrestrial water storage and weather forecasts. Root-zone soil moisture and snow water storage in land are critical parameters of the water cycle. The HydroCube Signals of Opportunity (SoOp) concept utilizes passive receivers to detect the reflection of strong existing P-band radio signals from geostationary Mobile Use Objective System (MUOS) communication satellites. The SWE remote sensing measurement principle using the P-band SoOp is based on the propagation delay (or phase change) of radio signals through the snowpack. The time delay of the reflected signal due to the snowpack with respect to snow-free conditions is directly proportional to the snowpack SWE. To address the ionospheric delay at P-band frequencies, the signals from both MUOS bands (360-380 MHz and 250-270 MHz) would be used. We have conducted an analysis to trade off the spatial resolution for a space-based sensor and measurement accuracy. Through modeling analysis, we find that the dual-band MUOS signals would allow estimation of soil moisture and surface roughness together. From the two MUOS frequencies at 260 MHz and 370 MHz, we can retrieve the soil moisture from the reflectivity ratio scaled by wavenumbers using the two P-band frequencies for MUOS. A modeling analysis using layered stratified model has been completed to determine the sensitivity requirements of HydroCube measurements. For mission concept demonstration, a field campaign has been conducted at the Fraser Experimental Forest in Colorado since February 2016. The data acquired has provided support to the HydroCube concept.

Imaging melanin cancer growth in-vivo using raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz and 100 MHz

Science.gov (United States)

Omar, Murad; Schwarz, Mathias; Soliman, Dominik; Symvoulidis, Panagiotis; Ntziachristos, Vasilis

2016-03-01

We used raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz, and at 100 MHz, to monitor tumor growth, and tumor angiogenesis, which is a central hallmark of cancer, in-vivo. In this study we compared the performance, and the effect of the 50 MHz, and the 100 MHz frequencies on the quality of the final image. The system is based on a reflection-mode implementation of RSOM. The detectors used are custom made, ultrawideband, and spherically focused. The use of such detectors enables light coupling from the same side as the detector, thus reflection-mode. Light is in turn coupled using a fiber bundle, and the detector is raster scanned in the xy-plane. Subsequently, to retrieve small features, the raw data are reconstructed using a multi-bandwidth, beamforming reconstruction algorithm. Comparison of the system performance at the different frequencies shows as expected a higher resolution in case of the 100 MHz detector compared to the 50 MHz. On the other hand the 50 MHz has a better SNR, can detect features from deeper layers, and has higher angular acceptance. Based on these characteristics the 50 MHz detector was mostly used. After comparing the performance we monitored the growth of B16F10 cells, melanin tumor, over the course of 9 days. We see correspondence between the optoacoustic measurements and the cryoslice validations. Additionally, in areas close to the tumor we see sprouting of new vessels, starting at day 4-5, which corresponds to tumor angiogenesis.

All-dielectric band stop filter at terahertz frequencies

Science.gov (United States)

Yin, Shan; Chen, Lin

2018-01-01

We design all-dielectric band stop filters with silicon subwavelength rod and block arrays at terahertz frequencies. Supporting magnetic dipole resonances originated from the Mia resonance, the all-dielectric filters can modulate the working band by simply varying the structural geometry, while eliminating the ohmic loss induced by the traditional metallic metamaterials and uninvolved with the complicated mechanism. The nature of the resonance in the silicon arrays is clarified, which is attributed to the destructive interference between the directly transmitted waves and the waves emitted from the magnetic dipole resonances, and the resonance frequency is determined by the dielectric structure. By particularly designing the geometrical parameters, the profile of the transmission spectrum can be tailored, and the step-like band edge can be obtained. The all-dielectric filters can realize 93% modulation of the transmission within 0.04 THz, and maintain the bandwidth of 0.05 THz. This work provides a method to develop THz functional devices, such as filters, switches and sensors.

Implementation and investigation of circular slot UWB antenna with dual-band-notched characteristics

Directory of Open Access Journals (Sweden)

DadashZadeh Gholamreza

2011-01-01

Full Text Available Abstract The design and analysis of an ultra wideband aperture antenna with dual-band-notched characteristics are presented. The proposed antenna consists of a circular ring exciting stub on the front side and a circular slot on the back ground plane. By utilizing a parasitic strip and a T-shaped stub on the antenna structure, two notched bands of 850 MHz (3.5-4.35 GHz and 900 MHz (5.05-5.95 GHz are achieved. The proposed antenna is fabricated and measured. Measured results show that this antenna operates from 2.3 GHz to upper 11 GHz for voltage standing wave ratio less than 2, except two frequency notched bands of 3.5-4.35 and 5.05-5.95 GHz. Moreover, the experimental results show that proposed antenna has stable radiation patterns and constant gain. A conceptual circuit model, which is based on the measured impedance of the proposed antenna, is also shown to investigate the dual-band-notched characteristics.

A Frequency Splitting Method For CFM Imaging

DEFF Research Database (Denmark)

Udesen, Jesper; Gran, Fredrik; Jensen, Jørgen Arendt

2006-01-01

The performance of conventional CFM imaging will often be degraded due to the relatively low number of pulses (4-10) used for each velocity estimate. To circumvent this problem we propose a new method using frequency splitting (FS). The FS method uses broad band chirps as excitation pulses instead...... of narrow band pulses as in conventional CFM imaging. By appropriate filtration, the returned signals are divided into a number of narrow band signals which are approximately disjoint. After clutter filtering the velocities are found from each frequency band using a conventional autocorrelation estimator......, a 5 MHz linear array transducer was used to scan a vessel situated at 30 mm depth with a maximum flow velocity of 0.1 m/s. The pulse repetition frequency was 1.8 kHz and the angle between the flow and the beam was 60 deg. A 15 mus chirp was used as excitation pulse and 40 independent velocity...

Advanced Wireless Local Area Networks in the Unlicensed Sub-1GHz ISM-bands

NARCIS (Netherlands)

Aust, S.H.

2014-01-01

This dissertation addresses the challenges of wireless local area networks (WLANs) that operate in the unlicensed sub-1GHz industrial, scientific, and medical (ISM) band. Frequencies in the 900MHz spectrum enable a wider coverage due to the longer propagation characteristics of the radio waves. To

Development of disposable membrane hydrophones for a frequency range from 1MHz to 10MHz.

Science.gov (United States)

Lee, Jae-Wan; Ohm, Won-Suk; Kim, Yong-Tae

2017-11-01

A method for fabricating disposable membrane hydrophones is presented. The disposable hydrophones are intended for onetime use in such damaging environments as chemically contaminating fluids and high-amplitude (peak amplitude ∼100MPa) shock wave fields, where the use of commercial membrane hydrophones is not recommended. Fabrication of a hydrophone is done using only off-the-shelf components and hand tools, which translates into ease of fabrication and orders-of-magnitude reduction in unit cost. In particular, poling and sputtering, the two processes that are chiefly responsible for the cost and difficulty associated with the conventional fabrication method, are replaced with the use of pre-poled polyvinylidene fluoride (PVDF) films and polyethylene terephthalate (PET)-coated aluminum foils, respectively. Despite the seemingly crude construction, these disposable hydrophones can exhibit voltage sensitivity response that compares favorably with that of commercial hydrophones. For example, one prototype having a 2mm×2mm active element shows the end-of-cable voltage sensitivity of -270 (±1.9) dB re 1V/μPa over the frequency range of 1-10MHz. Copyright © 2017 Elsevier B.V. All rights reserved.

Two-frequency radiospectrometer for studying paramagnetics under a strong magnetic field

International Nuclear Information System (INIS)

Vertii, A.A.; Gudym, I.Y.; Ivanchenko, I.V.

1994-01-01

A two-frequency radiospectrometer for studying electron paramagnetic resonance in the 120-150-GHz band and nuclear magnetic resonance in the 180-200-MHz band is described. The spectrometer is used to measure the properties of paramagnetics by a double-resonance technique in a magnetic field of up to 5 T at a temperature ranging from 1.7 to 20 degrees K

75 FR 19277 - PLMR Licensing; Frequency Coordination and Eligibility Issues

Science.gov (United States)

2010-04-14

... band (1427-1429.5 MHz), and non-medical telemetry in the upper half of the band (1429.5-1432 MHz). Non... secondary basis on those portions of the 1427-1432 MHz shared band where non-medical telemetry is primary...-medical telemetry has primary status. Some WMTS operations in the portions of the 1427-1432 MHz band where...

Multi-cavity locally resonant structure with the low frequency and broad band-gaps

Directory of Open Access Journals (Sweden)

Jiulong Jiang

2016-11-01

Full Text Available A multi-cavity periodic structure with the characteristic of local resonance was proposed in the paper. The low frequency band-gap structure was comparatively analyzed by the finite element method (FEM and electric circuit analogy (ECA. Low frequency band-gap can be opened through the dual influence of the coupling’s resonance in the cavity and the interaction among the couplings between structures. Finally, the influence of the structural factors on the band-gap was analyzed. The results show that the structure, which is divided into three parts equally, has a broader effective band-gap below the frequency of 200 Hz. It is also proved that reducing the interval between unit structures can increase the intensity of the couplings among the structures. And in this way, the width of band-gap would be expanded significantly. Through the parameters adjustment, the structure enjoys a satisfied sound insulation effect below the frequency of 500Hz. In the area of low frequency noise reduction, the structure has a lot of potential applications.

GaN-based High Efficiency Bidirectional DC-DC Converter with 10 MHz Switching Frequency

DEFF Research Database (Denmark)

Kruse, Kristian; Zhang, Zhe; Elbo, Mads

2017-01-01

-isolated bidirectional DC-DC converter equipped with Gallium Nitride (GaN) semiconductor transistors is presented. The converter’s operation principles, zero-voltage switching (ZVS) constraints and dead-time effects are studied. Moreover, the optimization and tradeoffs on the adopted high-frequency inductor...... are achieved. Moreover, the measured losses can match the theoretically calculated counterparts well, therefore the design and analysis are verified. However, from the experimental test carried out, it can also be seen, that making a compact converter, even for a GaN-based one, operate at 10 MHz and 100 W...

Narrowband-to-Narrowband Frequency Reconfiguration with Harmonic Suppression Using Fractal Dipole Antenna

Directory of Open Access Journals (Sweden)

S. A. Hamzah

2013-01-01

Full Text Available Harmonic suppressed fractal antenna with switches named TMFDB25 is developed to select desired frequency band from 400 MHz to 3.5 GHz. The radiating element length is changed to tune the operating frequency while the stub is used to eliminate the undesired harmonic frequency. The balun circuit is reduced by 75% from the original size. The antenna is built on a low loss material. It has the ability to select a single frequency out of fifteen different bands and maintain the omnidirectional radiation pattern properties. Furthermore, the antenna is designed, built, and tested. Simulation and measurement results show that the antenna operates well at the specific frequency range. Therefore, the antenna is suitable to be used for switching frequencies in the band of TV, GSM900/1800, 3G, ISM 2.4 GHz, and above.

Simultaneous multi-band channel sounding at mm-Wave frequencies

DEFF Research Database (Denmark)

Müller, Robert; Häfner, Stephan; Dupleich, Diego

2016-01-01

The vision of multi Gbit/s data rates in future mobile networks requires the change to millimeter wave (mm-Wave) frequencies for increasing bandwidth. As a consequence, new technologies have to be deployed to tackle the drawbacks of higher frequency bands, e.g. increased path loss. Development an...

A Broadband VHF-L Band Cavity-Backed Slot Spiral Antenna

Science.gov (United States)

2005-05-01

each new frequency. When the frequency list is completed, the Flight Test Engineer will contact the Test Technician and request any necessary...immediately required elsewhere. Frequency List ; 50.05 MHz, 144.05 MHz, 432.05 MHz, 902.05 MHz, 1.29605 GHz...Repeat Completed? (Y/N) Test Completed? (Y/N) Frequency List ; 50.05 MHz, 144.05 MHz, 432.05 MHz, 902.05 MHz, 1.29605 GHz

A matched Bow-tie antenna at 433MHz for use in underwater wireless sensor networks

International Nuclear Information System (INIS)

Abdou, A A; Shaw, A; Mason, A; Al-Shamma'a, A; Cullen, J; Wylie, S; Diallo, M

2013-01-01

Electromagnetic (EM) wave propagation underwater is been disregarded because of attenuation at high frequencies, however the theory predicts that propagation is possible at some useful distance in the lower Industrial, Scientific and Medical (ISM) band. Common transceivers rely on narrowband antennas and matching circuit. The aim of this paper is to design a broadband 433MHz bow-tie antenna and experiment it in air and water without a matching circuit. This antenna could be attached to wireless transceivers and form a Wireless Sensor Network for deployment in various underwater applications. The bow-tie antennas were designed, simulated and constructed in laboratory. Experiments were setup carefully by using a completely isolated transmitter from electronics to avoid airborne transmission. The 433MHz. bow-tie proved its suitability for use in Underwater.

A new low-cost 10 ns pulsed K(a)-band radar.

Science.gov (United States)

Eskelinen, Pekka; Ylinen, Juhana

2011-07-01

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

HAPS Gateway Link in the 5850-7075 MHz and Coexistence with Fixed Satellite Service

Directory of Open Access Journals (Sweden)

M. Ahmed

2013-09-01

Full Text Available Gateway link is essential to connect HAPS platform to terrestrial based networks. This crucial link is incorporated in HAPS fixed service spectrum allocation in considerably high frequencies, renders the link for more attenuations by atmospheric gases, and rain effects, especially when the regional climate is not favorable. However, under the agenda item 1.20 of World Radio Conference-2012 (WRC-12 new HAPS allocation in the 5850-7075 MHz band is proposed. Although, spectrum features are incomparably reliable, on the contrary, Fixed Satellite Service (FSS uplink transmissions will have signal levels much higher than those in HAPS systems and have the potential for causing interference at the HAPS gateway receiver. In this article a key aspect of co-channel interference phenomena is investigated to facilitate optimum frequency sharing in the band in question. By proposing mitigation techniques and statistical method this generic prediction model enhances the capability of the HAPS spectrum sharing and provides flexibility in spectrum planning for different fixed services.

Brain alterations in low-frequency fluctuations across multiple bands in obsessive compulsive disorder.

Science.gov (United States)

Giménez, Mònica; Guinea-Izquierdo, Andrés; Villalta-Gil, Victoria; Martínez-Zalacaín, Ignacio; Segalàs, Cinto; Subirà, Marta; Real, Eva; Pujol, Jesús; Harrison, Ben J; Haro, Josep Maria; Sato, Joao R; Hoexter, Marcelo Q; Cardoner, Narcís; Alonso, Pino; Menchón, José Manuel; Soriano-Mas, Carles

2017-12-01

The extent of functional abnormalities in frontal-subcortical circuits in obsessive-compulsive disorder (OCD) is still unclear. Although neuroimaging studies, in general, and resting-state functional Magnetic Resonance Imaging (rs-fMRI), in particular, have provided relevant information regarding such alterations, rs-fMRI studies have been typically limited to the analysis of between-region functional connectivity alterations at low-frequency signal fluctuations (i.e., <0.08 Hz). Conversely, the local attributes of Blood Oxygen Level Dependent (BOLD) signal across different frequency bands have been seldom studied, although they may provide valuable information. Here, we evaluated local alterations in low-frequency fluctuations across different oscillation bands in OCD. Sixty-five OCD patients and 50 healthy controls underwent an rs-fMRI assessment. Alterations in the fractional amplitude of low-frequency fluctuations (fALFF) were evaluated, voxel-wise, across four different bands (from 0.01 Hz to 0.25 Hz). OCD patients showed decreased fALFF values in medial orbitofrontal regions and increased fALFF values in the dorsal-medial prefrontal cortex (DMPFC) at frequency bands <0.08 Hz. This pattern was reversed at higher frequencies, where increased fALFF values also appeared in medial temporal lobe structures and medial thalamus. Clinical variables (i.e., symptom-specific severities) were associated with fALFF values across the different frequency bands. Our findings provide novel evidence about the nature and regional distribution of functional alterations in OCD, which should contribute to refine neurobiological models of the disorder. We suggest that the evaluation of the local attributes of BOLD signal across different frequency bands may be a sensitive approach to further characterize brain functional alterations in psychiatric disorders.

A simple, tunable, and highly sensitive radio-frequency sensor.

Science.gov (United States)

Cui, Yan; Sun, Jiwei; He, Yuxi; Wang, Zheng; Wang, Pingshan

2013-08-05

We report a radio frequency (RF) sensor that exploits tunable attenuators and phase shifters to achieve high-sensitivity and broad band frequency tunability. Three frequency bands are combined to enable sensor operations from ∼20 MHz to ∼38 GHz. The effective quality factor ( Q eff ) of the sensor is as high as ∼3.8 × 10 6 with 200  μ l of water samples. We also demonstrate the measurement of 2-proponal-water-solution permittivity at 0.01 mole concentration level from ∼1 GHz to ∼10 GHz. Methanol-water solution and de-ionized water are used to calibrate the RF sensor for the quantitative measurements.

Ultrawide low frequency band gap of phononic crystal in nacreous composite material

International Nuclear Information System (INIS)

Yin, J.; Huang, J.; Zhang, S.; Zhang, H.W.; Chen, B.S.

2014-01-01

The band structure of a nacreous composite material is studied by two proposed models, where an ultrawide low frequency band gap is observed. The first model (tension-shear chain model) with two phases including brick and mortar is investigated to describe the wave propagation in the nacreous composite material, and the dispersion relation is calculated by transfer matrix method and Bloch theorem. The results show that the frequency ranges of the pass bands are quite narrow, because a special tension-shear chain motion in the nacreous composite material is formed by some very slow modes. Furthermore, the second model (two-dimensional finite element model) is presented to investigate its band gap by a multi-level substructure scheme. Our findings will be of great value to the design and synthesis of vibration isolation materials in a wide and low frequency range. Finally, the transmission characteristics are calculated to verify the results. - Highlights: • A Brick-and-Mortar structure is used to discuss wave propagation through nacreous materials. • A 1D Bloch wave solution of nacreous materials with a tension-shear chain model is obtained. • The band structure and transmission characteristics of nacreous materials with the FE model are examined. • An ultrawide low frequency band gap is found in nacreous materials with both theory and FE model

Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

KAUST Repository

Chandran, Akhil A.

2016-09-15

Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator\\'s nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli\\'s beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

KAUST Repository

Chandran, Akhil A.; Younis, Mohammad I.

2016-01-01

Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator's nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli's beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

The driving frequency effects on the atmospheric pressure corona jet plasmas from low frequency to radio frequency

International Nuclear Information System (INIS)

Kim, Dan Bee; Jung, H.; Gweon, B.; Rhee, J. K.; Choe, W.; Moon, S. Y.

2011-01-01

Lately, the atmospheric pressure jet type corona plasma, which has been typically driven by dc to low frequency (LF: several tens of kHz), is often generated by using radio frequency of 13.56 MHz. Yet, the relationship between the plasma and its driving frequency has seldom been investigated. Hence, in this study, dependence of the atmospheric pressure corona plasma characteristics on the driving frequency was explored experimentally from LF to rf (5 kHz-13.56 MHz). The plasmas generated by the driving frequency under 2 MHz were cylindrical shape of several tens of millimeters long while the 13.56 MHz plasma is spherical and a few millimeters long. As the driving frequency was increased, the plasma length became shortened. At the lower driving frequencies (below 2 MHz), the plasmas existed as positive streamer and negative glow for each half period of the applied voltage, but the discharge was more continuous in time for the 13.56 MHz plasma. It was inferred from the measured I-V curves that the higher driving frequency induced higher discharge currents, and the gas temperature was increased as the driving frequency was increased.

Frequency band analysis of muscle activation during cycling to exhaustion

Directory of Open Access Journals (Sweden)

Fernando Diefenthaeler

2012-04-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p243 Lower limb muscles activation was assessed during cycling to exhaustion using frequency band analysis. Nine cyclists were evaluated in two days. On the first day, cyclists performed a maximal incremental cycling exercise to measure peak power output, which was used on the second day to define the workload for a constant load time to exhaustion cycling exercise (maximal aerobic power output from day 1. Muscle activation of vastus lateralis (VL, long head of biceps femoris (BF, lateral head of gastrocnemius (GL, and tibialis anterior (TA from the right lower limb was recorded during the time to exhaustion cycling exercise. A series of nine band-pass Butterworth digital filters was used to analyze muscle activity amplitude for each band. The overall amplitude of activation and the high and low frequency components were defined to assess the magnitude of fatigue effects on muscle activity via effect sizes. The profile of the overall muscle activation during the test was analyzed using a second order polynomial, and the variability of the overall bands was analyzed by the coefficient of variation for each muscle in each instant of the test. Substantial reduction in the high frequency components of VL and BF activation was observed. The overall and low frequency bands presented trivial to small changes for all muscles. High relationship between the second order polynomial fitting and muscle activity was found (R2 > 0.89 for all muscles. High variability (~25% was found for muscle activation at the four instants of the fatigue test. Changes in the spectral properties of the EMG signal were only substantial when extreme changes in fatigue state were induced.

Cermet based metamaterials for multi band absorbers over NIR to LWIR frequencies

International Nuclear Information System (INIS)

Pradhan, Jitendra K; Behera, Gangadhar; Anantha Ramakrishna, S; Agarwal, Amit K; Ghosh, Amitava

2017-01-01

Cermets or ceramic-metals are known for their use in solar thermal technologies for their absorption across the solar band. Use of cermet layers in a metamaterial perfect absorber allows for flexible control of infra-red absorption over the short wave infra-red, to long wave infra-red bands, while keeping the visible/near infra-red absorption properties constant. We design multilayered metamaterials consisting of a conducting ground plane, a low metal volume fraction cermet/ZnS as dielectric spacer layers, and a top structured layer of an array of circular discs of metal/high volume metal fraction cermet that give rise to specified absorption bands in the near-infra-red (NIR) frequencies, as well as any specified band at SWIR–LWIR frequencies. Thus, a complete decoupling of the absorption at optical/NIR frequencies and the infra-red absorption behaviour of a structured metamaterial is demonstrated. (paper)

75 FR 9586 - Solicitation of Participation In and Public Meeting to Discuss Public Safety 700 MHz Broadband...

Science.gov (United States)

2010-03-03

... to local, state and tribal public safety agencies (i.e. fire, police, emergency medical services...\\ Implementing a Nationwide, Broadband, Interoperable Public Safety Network in the 700 MHz Band, FCC WT Docket No... technology deployed in the 700 MHz bands, specific to the needs of public safety agencies. NIST has developed...

A reconfigurable frequency-selective surface for dual-mode multi-band filtering applications

Science.gov (United States)

Majidzadeh, Maryam; Ghobadi, Changiz; Nourinia, Javad

2017-03-01

A reconfigurable single-layer frequency-selective surface (FSS) with dual-mode multi-band modes of operation is presented. The proposed structure is printed on a compact 10 × 10 mm2 FR4 substrate with the thickness of 1.6 mm. A simple square loop is printed on the front side while another one along with two defected vertical arms is deployed on the backside. To realise the reconfiguration, two pin diodes are embedded on the backside square loop. Suitable insertion of conductive elements along with pin diodes yields in dual-mode multi-band rejection of applicable in service frequency ranges. The first operating mode due to diodes' 'ON' state provides rejection of 2.4 GHz WLAN in 2-3 GHz, 5.2/5.8 GHz WLAN and X band in 5-12 GHz, and a part of Ku band in 13.9-16 GHz. In diodes 'OFF' state, the FSS blocks WLAN in 4-7.3 GHz, X band in 8-12.7 GHz as well as part of Ku band in 13.7-16.7 GHz. As well, high attenuation of incident waves is observed by a high shielding effectiveness (SE) in the blocked frequency bands. Also, a stable behaviour against different polarisations and angles of incidence is obtained. Comprehensive studies are conducted on a fabricated prototype to assess its performance from which encouraging results are obtained.

VLITE Surveys the Sky: A 340 MHz Companion to the VLA Sky Survey (VLASS)

Science.gov (United States)

Peters, Wendy; Clarke, Tracy; Brisken, Walter; Cotton, William; Richards, Emily E.; Giacintucci, Simona; Kassim, Namir

2018-01-01

The VLA Low Band Ionosphere and Transient Experiment (VLITE; ) is a commensal observing system on the Karl G. Janksy Very Large Array (VLA) which was developed by the Naval Research Laboratory and NRAO. A 64 MHz sub-band from the prime focus 240-470 MHz dipoles is correlated during nearly all regular VLA observations. VLITE uses dedicated samplers and fibers, as well as a custom designed, real-time DiFX software correlator, and requires no additional resources from the VLA system running the primary science program. The experiment has been operating since November 2014 with 10 antennas; a recent expansion in summer 2017 increased that number to 16 and more than doubled the number of baselines.The VLA Sky Survey (VLASS; ), is an ongoing survey of the entire sky visible to the VLA at a frequency of 2-4 GHz. The observations are made using an "on-the-fly" (OTF) continuous RA scanning technique which fills in the sky by observing along rows of constant declination. VLITE breaks the data into 2-second integrations and correlates these at a central position every 1.5 degrees. All data for each correlator position is imaged separately, corrected and weighted by an appropriately elongated primary beam model, and then combined in the image plane to create a mosaic of the sky. A catalog of the sources is extracted to provide a 340 MHz sky model.We present preliminary images and catalogs from the 2017 VLASS observations which began in early September, 2017, and continued on a nearly daily basis throughout the fall. In addition to providing a unique sky model at 340 MHz, these data complement VLASS by providing spectral indices for all cataloged sources.

Electrodynamic characterisitcs measurements of higher order modes in S-band cavity

Science.gov (United States)

Donetsky, R.; Lalayan, M.; Sobenin, N. P.; Orlov, A.; Bulygin, A.

2017-12-01

The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM 110 and TE 111 for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

The dielectric properties of human pineal gland tissue and RF absorption due to wireless communication devices in the frequency range 400-1850 MHz

International Nuclear Information System (INIS)

Schmid, Gernot; Ueberbacher, Richard; Samaras, Theodoros; Tschabitscher, Manfred; Mazal, Peter R

2007-01-01

In order to enable a detailed analysis of radio frequency (RF) absorption in the human pineal gland, the dielectric properties of a sample of 20 freshly removed pineal glands were measured less than 20 h after death. Furthermore, a corresponding high resolution numerical model of the brain region surrounding the pineal gland was developed, based on a real human tissue sample. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-1850 MHz were carried out. For typical output power values of real handheld mobile communication devices, the obtained results showed only very small amounts of absorbed RF power in the pineal gland when compared to SAR limits according to international safety standards. The highest absorption was found for the 400 MHz irradiation. In this case the RF power absorbed inside the pineal gland (organ mass 96 mg) was as low as 11 μW, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power in the pineal gland were found to be lower by a factor of 4.2 and 36, respectively. These results indicate that temperature-related biologically relevant effects on the pineal gland induced by the RF emissions of typical handheld mobile communication devices are unlikely

Development of nanometer resolution C-Band radio frequency beam position monitors in the Final Focus Test Beam

Energy Technology Data Exchange (ETDEWEB)

Slaton, T.; Mazaheri, G. [Stanford Univ., CA (US). Stanford Linear Accelerator Center; Shintake, T. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

1998-08-01

Using a 47 GeV electron beam, the Final Focus Test Beam (FFTB) produces vertical spot sizes around 70 nm. These small beam sizes introduce an excellent opportunity to develop and test high resolution Radio Frequency Beam Position Monitors (RF-BPMs). These BPMs are designed to measure pulse to pulse beam motion (jitter) at a theoretical resolution of approximately 1 nm. The beam induces a TM{sub 110} mode with an amplitude linearly proportional to its charge and displacement from the BPM's (cylindrical cavity) axis. The C-band (5,712 MHz) TM{sub 110} signal is processed and converted into beam position for use by the Stanford Linear Collider (SLC) control system. Presented are the experimental procedures, acquisition, and analysis of data demonstrating resolution of jitter near 25 nm. With the design of future e{sup +}e{sup -} linear colliders requiring spot sizes close to 3 nm, understanding and developing RF-BPMs will be essential in resolving and controlling jitter.

Development of nanometer resolution C-Band radio frequency beam position monitors in the Final Focus Test Beam

International Nuclear Information System (INIS)

Slaton, T.; Mazaheri, G.

1998-08-01

Using a 47 GeV electron beam, the Final Focus Test Beam (FFTB) produces vertical spot sizes around 70 nm. These small beam sizes introduce an excellent opportunity to develop and test high resolution Radio Frequency Beam Position Monitors (RF-BPMs). These BPMs are designed to measure pulse to pulse beam motion (jitter) at a theoretical resolution of approximately 1 nm. The beam induces a TM 110 mode with an amplitude linearly proportional to its charge and displacement from the BPM's (cylindrical cavity) axis. The C-band (5,712 MHz) TM 110 signal is processed and converted into beam position for use by the Stanford Linear Collider (SLC) control system. Presented are the experimental procedures, acquisition, and analysis of data demonstrating resolution of jitter near 25 nm. With the design of future e + e - linear colliders requiring spot sizes close to 3 nm, understanding and developing RF-BPMs will be essential in resolving and controlling jitter

Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method)

DEFF Research Database (Denmark)

Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf......Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf...

Band Width of Acoustic Resonance Frequency Relatively Natural Frequency of Fuel Rod Vibration

Energy Technology Data Exchange (ETDEWEB)

Proskuryakov, Konstantin Nicolaevich; Moukhine, V.S.; Novikov, K.S.; Galivets, E.Yu. [MPEI - TU, 14, Krasnokazarmennaya str., Moscow, 111250 (Russian Federation)

2009-06-15

In flow induced vibrations the fluid flow is the energy source that causes vibration. Acoustic resonance in piping may lead to severe problems due to over-stressing of components or significant losses of efficiency. Steady oscillatory flow in NPP primary loop can be induced by the pulsating flow introduced by reactor circulating pump or may be set up by self-excitation. Dynamic forces generated by the turbulent flow of coolant in reactor cores cause fuel rods (FR) and fuel assembly (FA) to vibrate. Flow-induced FR and FA vibrations can generally be broken into three groups: large amplitude 'resonance type' vibrations, which can cause immediate rod failure or severe damage to the rod and its support structure, middle amplitude 'within bandwidth of resonance frequency type' vibrations responsible for more gradual wear and fatigue at the contact surface between the fuel cladding and rod support and small amplitude vibrations, 'out of bandwidth of resonance frequency type' responsible for permissible wear and fatigue at the contact surface between the fuel cladding and rod support. Ultimately, these vibration types can result in a cladding breach, and therefore must be accounted for in the thermal hydraulic design of FR and FA and reactor internals. In paper the technique of definition of quality factor (Q) of acoustic contour of the coolant is presented. The value of Q defines a range of frequencies of acoustic fluctuations of the coolant within which the resonance of oscillations of the structure and the coolant is realized. Method of evaluation of so called band width (BW) of acoustic resonance frequency is worked out and presented in the paper. BW characterises the range of the frequency of coolant pressure oscillations within which the frequency of coolant pressure oscillations matches the fuel assembly's natural frequency of vibration (its resonance frequency). Paper show the way of detuning acoustic resonance from natural

Band-gap tunable dielectric elastomer filter for low frequency noise

Science.gov (United States)

Jia, Kun; Wang, Mian; Lu, Tongqing; Zhang, Jinhua; Wang, Tiejun

2016-05-01

In the last decades, diverse materials and technologies for sound insulation have been widely applied in engineering. However, suppressing the noise radiation at low frequency still remains a challenge. In this work, a novel membrane-type smart filter, consisting of a pre-stretched dielectric elastomer membrane with two compliant electrodes coated on the both sides, is presented to control the low frequency noise. Since the stiffness of membrane dominates its acoustic properties, sound transmission band-gap of the membrane filter can be tuned by adjusting the voltage applied to the membrane. The impedance tube experiments have been carried out to measure the sound transmission loss (STL) of the filters with different electrodes, membrane thickness and pre-stretch conditions. The experimental results show that the center frequency of sound transmission band-gap mainly depends on the stress in the dielectric elastomer, and a large band-gap shift (more than 60 Hz) can be achieved by tuning the voltage applied to the 85 mm diameter VHB4910 specimen with pre-stretch {λ }0=3. Based on the experimental results and the assumption that applied electric field is independent of the membrane behavior, 3D finite element analysis has also been conducted to calculate the membrane stress variation. The sound filter proposed herein may provide a promising facility to control low frequency noise source with tonal characteristics.

A multispacecraft event study of Pc5 ultralow-frequency waves in the magnetosphere and their external drivers

International Nuclear Information System (INIS)

Wang, Chih-Ping; Thorne, Richard; Liu, Terry Z.; Hartinger, Michael D.; Nagai, Tsugunobu

2017-01-01

We investigate a quiet time event of magnetospheric Pc5 ultralow-frequency (ULF) waves and their likely external drivers using multiple spacecraft observations. Enhancements of electric and magnetic field perturbations in two narrow frequency bands, 1.5–2 mHz and 3.5–4 mHz, were observed over a large radial distance range from r ~ 5 to 11 RE. During the first half of this event, perturbations were mainly observed in the transverse components and only in the 3.5–4 mHz band. In comparison, enhancements were stronger during the second half in both transverse and compressional components and in both frequency bands. No indication of field line resonances was found for these magnetic field perturbations. Perturbations in these two bands were also observed in the magnetosheath, but not in the solar wind dynamic pressure perturbations. For the first interval, good correlations between the flow perturbations in the magnetosphere and magnetosheath and an indirect signature for Kelvin-Helmholtz (K-H) vortices suggest K-H surface waves as the driver. For the second interval, good correlations are found between the magnetosheath dynamic pressure perturbations, magnetopause deformation, and magnetospheric waves, all in good correspondence to interplanetary magnetic field (IMF) discontinuities. The characteristics of these perturbations can be explained by being driven by foreshock perturbations resulting from these IMF discontinuities. This event shows that even during quiet periods, K-H-unstable magnetopause and ion foreshock perturbations can combine to create a highly dynamic magnetospheric ULF wave environment

A broad-band (0.2-8 MHz) multiple-harmonic VITROVAC-filled acceleration structure

Energy Technology Data Exchange (ETDEWEB)

Ausset, P.; Charruau, G.; De Menezes, D.; Fougeron, C. [Laboratoire National Saturne, Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Etzkorn, F.J.; Papureanu, S.; Schnase, A.; Meuth, H. [Forschungszentrum Juelich GmbH (Germany)

1994-12-31

Higher or multiple-harmonic acceleration drives in synchrotrons are desirable, when passing the transition point, applying stochastic cooling on a bunched beam, or for many other longitudinal beam manipulations, as bunch stretching or compression. As proof-of-principle, virtually arbitrary, digitally synthesized voltage waveforms, employing contents up to fourth harmonic in the range 0.2-8 MHz, could be generated at the gap of one single (symmetric re-entrant) cavity, filled with discs of the novel ferritic amorphous metal VITROVAC of VAC, Hanau. A 10 kW amplifier produces voltages in the kV-range. As relevant examples, we achieved a flat-top waveform suitable for the transition (+27 deg, 10{sup -3} max. error), a fourth-order flattened bucket for bunched-beam cooling, and a harmonic bucket with linear restoring force. The compact cavity system should be well suited for any proton or heavy ion device operating in this frequency range, and therapy-oriented rings. (author). 9 refs., 6 figs.

A broad-band (0.2-8 MHz) multiple-harmonic VITROVAC-filled acceleration structure

International Nuclear Information System (INIS)

Ausset, P.; Charruau, G.; De Menezes, D.; Fougeron, C.; Etzkorn, F.J.; Papureanu, S.; Schnase, A.; Meuth, H.

1994-01-01

Higher or multiple-harmonic acceleration drives in synchrotrons are desirable, when passing the transition point, applying stochastic cooling on a bunched beam, or for many other longitudinal beam manipulations, as bunch stretching or compression. As proof-of-principle, virtually arbitrary, digitally synthesized voltage waveforms, employing contents up to fourth harmonic in the range 0.2-8 MHz, could be generated at the gap of one single (symmetric re-entrant) cavity, filled with discs of the novel ferritic amorphous metal VITROVAC of VAC, Hanau. A 10 kW amplifier produces voltages in the kV-range. As relevant examples, we achieved a flat-top waveform suitable for the transition (+27 deg, 10 -3 max. error), a fourth-order flattened bucket for bunched-beam cooling, and a harmonic bucket with linear restoring force. The compact cavity system should be well suited for any proton or heavy ion device operating in this frequency range, and therapy-oriented rings. (author). 9 refs., 6 figs

A 65nm CMOS low-power MedRadio-band integer-N cascaded phase-locked loop for implantable medical systems.

Science.gov (United States)

Wang, Yi-Xiao; Chen, Wei-Ming; Wu, Chung-Yu

2014-01-01

This paper presents a low-power MedRadio-band integer-N phase-locked Loop (PLL) system which is composed of two charge-pump PLLs cascade connected. The PLL provides the operation clock and local carrier signals for an implantable medical electronic system. In addition, to avoid the off-chip crystal oscillator, the 13.56 MHz Industrial, Scientific and Medical (ISM) band signal from the wireless power transmission system is adopted as the input reference signal for the PLL. Ring-based voltage controlled oscillators (VCOs) with current control units are adopted to reduce chip area and power dissipation. The proposed cascaded PLL system is designed and implemented in TSMC 65-nm CMOS technology. The measured jitter for 216.96 MHz signal is 12.23 ps and the phase noise is -65.9 dBc/Hz at 100 kHz frequency offset under 402.926 MHz carrier frequency. The measured power dissipations are 66 μW in the first PLL and 195 μW in the whole system under 1-V supply voltage. The chip area is 0.1088 mm(2) and no off-chip component is required which is suitable for the integration of the implantable medical electronic system.

Design and simulation of self-biased circulators in the ultra high frequency band

International Nuclear Information System (INIS)

Wang Jianwei; Geiler, Anton; Mistry, Perhaad; Kaeli, David R.; Harris, Vincent G.; Vittoria, Carmine

2012-01-01

Theoretical models were developed to design self-biased Y-junction circulators operating at ultra high frequency (UHF). The proposed circulator designs consist of insulating nanowires of yttrium iron garnet (YIG) embedded in high permittivity barium–strontium titanate (BSTO) substrates. A design with as many as 10 5 or greater wires may be considered in its entirety to determine the electromagnetic scattering S-parameters of a circulator design, thus helping to mitigate the computational limitations of the available finite element method (FEM) tools. The approach seeks to represent the nanowires and the BSTO substrate by an equivalent medium with effective properties inclusive of the average saturation magnetization, dynamic demagnetizing fields, and permittivity. The effective medium approach was validated in comparison with the FEM models. Using the proposed approach, a self-biased junction circulator consisting of YIG nanowires embedded in a BSTO substrate was designed and simulated in which the center frequency insertion loss was calculated to be as low as 0.16 dB with isolation of −42.3 dB at 1 GHz. The 20 dB bandwidth was calculated to be 50 MHz. These results suggest that practical self-biased circulators at the UHF band are feasible. - Highlights: ► Presented a self-biased Y-junction circulator topology on composite substrate with YIG nanowires and high permittivity BSTO. ► Developed an equivalent model to characterize the composite substrate. ► Designed a self-biased junction circulator consisting of YIG nanowires embedded in a BSTO substrate at 1 GHz.

Dual-band and high-efficiency polarization converter based on metasurfaces at microwave frequencies

Science.gov (United States)

Liu, Yajun; Xia, Song; Shi, Hongyu; Zhang, Anxue; Xu, Zhuo

2016-06-01

We present a dual-band and high-efficiency polarization converter in microwave regime. The proposed converter can convert a linearly polarized wave to its cross-polarized wave for two distinct bands: Ku (11.5-20.0 GHz) and Ka (28.8-34.0 GHz). It can also convert the linearly polarized wave to a circularly polarized wave at four other frequencies. The experimental results are in good agreement with simulation results for both frequency bands. The polarization conversion ratio is above 0.94 for the Ku-band and 0.90 for the Ka-band. Furthermore, the converter can achieve dual-band and high-efficiency polarization conversion over angles of incidence up to 45°. The converter is also polarization-selective in that only the x- and y-polarized waves can be converted. The physical mechanism of the dual-band polarization conversion effect is interpreted via decomposed electric field components that couple with different plasmon resonance modes of the structure.

Application of energies of optimal frequency bands for fault diagnosis based on modified distance function

Energy Technology Data Exchange (ETDEWEB)

Zamanian, Amir Hosein [Southern Methodist University, Dallas (United States); Ohadi, Abdolreza [Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of)

2017-06-15

Low-dimensional relevant feature sets are ideal to avoid extra data mining for classification. The current work investigates the feasibility of utilizing energies of vibration signals in optimal frequency bands as features for machine fault diagnosis application. Energies in different frequency bands were derived based on Parseval's theorem. The optimal feature sets were extracted by optimization of the related frequency bands using genetic algorithm and a Modified distance function (MDF). The frequency bands and the number of bands were optimized based on the MDF. The MDF is designed to a) maximize the distance between centers of classes, b) minimize the dispersion of features in each class separately, and c) minimize dimension of extracted feature sets. The experimental signals in two different gearboxes were used to demonstrate the efficiency of the presented technique. The results show the effectiveness of the presented technique in gear fault diagnosis application.

Attenuation and velocity dispersion in the exploration seismic frequency band

Science.gov (United States)

Sun, Langqiu

In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

Examination of High Frequency MHz Rheology of Filled Polymer Composites and Photopolymers

Science.gov (United States)

Yeh, Chyi-Huey Joshua

The quartz crystal microbalance (QCM) is a versatile characterization tool capable of tracking changes in areal mass and high frequency MHz rheology of micron thick films. The QCM primarily consists of a single quartz disc with electrodes deposited on both sides of the disc. Due to the piezoelectric nature of quartz, introduction of an oscillating voltage near the resonance condition of the quartz disc produces a traveling shear wave that can be measured with electrical admittance analysis. This technique behaves like an acoustic reflectometer, where an induced mechanical shear wave propagates and reflects at the interfaces between material layers with differing acoustic impedances. Based on how the shear wave interacts with the interfaces, information on the material properties can be quantitatively modeled. In this dissertation, a quantitative approach of determining the magnitude and sources of error is presented, so that interpretation of viscoelastic information and areal mass changes can be performed with confidence. Specifically, the role of anharmonic coupling with harmonic modes are explored and simulated with COMSOL Multiphysics. Several case studies motivating and highlighting the utility of the QCM is presented. The fracture and thermal aging behavior of several nanofilled silicone elastomers are examined using traditional mechanical tests, such as pure shear geometry and dynamic mechanical analysis (DMA). Results can be qualitatively explained by the concept of dynamic mechanical heterogeneity, where a high mechanical contrast is desired for high fracture toughness. However, DMA results can be difficult to interpret (especially at shifted high frequencies) due to thermal rheological complexity, a characteristic commonly found in many polymer composites. This motivates the application of the QCM, where MHz viscoelastic behavior can be directly probed, providing insight on the dissipative behavior at local length scales. Investigation of polysilicate

Experimental performance assessment of the sub-band minimum variance beamformer for ultrasound imaging

DEFF Research Database (Denmark)

Diamantis, Konstantinos; Greenaway, Alan H.; Anderson, Tom

2017-01-01

Recent progress in adaptive beamforming techniques for medical ultrasound has shown that current resolution limits can be surpassed. One method of obtaining improved lateral resolution is the Minimum Variance (MV) beamformer. The frequency domain implementation of this method effectively divides...... the broadband ultrasound signals into sub-bands (MVS) to conform with the narrow-band assumption of the original MV theory. This approach is investigated here using experimental Synthetic Aperture (SA) data from wire and cyst phantoms. A 7 MHz linear array transducer is used with the SARUS experimental...

Performance Analysis of Downlink Inter-band Carrier Aggregation in LTE-Advanced

DEFF Research Database (Denmark)

Wang, Hua; Rosa, Claudio; Pedersen, Klaus

2011-01-01

CC can be different. In this paper, we investigate the downlink resource allocation for inter-band CA, i.e., how to assign carrier(s) to different UEs. A simple yet effective G-factor based carrier selection algorithm, which takes both traffic load and radio channel characteristics......Carrier aggregation (CA) is one of the most distinct features for LTE-Advanced systems, which can support a much wider transmission bandwidth up to 100 MHz by aggregating two or more individual component carriers (CCs) belonging to the same (intra-band) or different (inter-band) frequency bands....... With CA, it is possible to schedule a user equipment (UE) on multiple CCs simultaneously. From radio resource management (RRM) perspective, CC selection plays an important role in optimizing the system performance, especially in the case of inter-band CA where the radio propagation characteristics of each...

Binary particle swarm optimization for frequency band selection in motor imagery based brain-computer interfaces.

Science.gov (United States)

Wei, Qingguo; Wei, Zhonghai

2015-01-01

A brain-computer interface (BCI) enables people suffering from affective neurological diseases to communicate with the external world. Common spatial pattern (CSP) is an effective algorithm for feature extraction in motor imagery based BCI systems. However, many studies have proved that the performance of CSP depends heavily on the frequency band of EEG signals used for the construction of covariance matrices. The use of different frequency bands to extract signal features may lead to different classification performances, which are determined by the discriminative and complementary information they contain. In this study, the broad frequency band (8-30 Hz) is divided into 10 sub-bands of band width 4 Hz and overlapping 2 Hz. Binary particle swarm optimization (BPSO) is used to find the best sub-band set to improve the performance of CSP and subsequent classification. Experimental results demonstrate that the proposed method achieved an average improvement of 6.91% in cross-validation accuracy when compared to broad band CSP.

Reduction of environmental MHz noise for SQUID application

Energy Technology Data Exchange (ETDEWEB)

Araya, T. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: araya@sup.ee.es.osaka-u.ac.jp; Kitamura, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Kamishiro, M. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Sakuta, K. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Itozaki, H. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: itozaki@ee.es.osaka-u.ac.jp

2006-10-01

It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise.

Reduction of environmental MHz noise for SQUID application

International Nuclear Information System (INIS)

Araya, T.; Kitamura, Y.; Kamishiro, M.; Sakuta, K.; Itozaki, H.

2006-01-01

It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise

The Path from VLITE to ngLOBO: A Roadmap for Evolving a Low Frequency Commensal System from the JVLA to the ngVLA

Science.gov (United States)

Kassim, Namir E.; Clarke, Tracy; Giacintucci, Simona; Helmboldt, Joseph; Ray, Paul S.; Peters, Wendy; Polisensky, Emil; hicks, Brian C.; Brisken, Walter; hyman, Scott D.; Deneva, Julia; Kerr, Matthew T.; Taylor, Gregory; Dowell, Jayce; Schinzel, Frank K.

2018-01-01

The VLA Low-band Ionosphere and Transient Experiment (VLITE, ) is a commensal observing system on the NRAO Karl G. Jansky Very Large Array (VLA). The separate optical path of the prime-focus sub-GHz dipole feeds and the Cassegrain-focus GHz feeds provided an opportunity to expand the simultaneous frequency operation of the VLA through joint observations across both systems. 16 VLA antennas are outfitted with dedicated samplers and use spare fibers to transport the 320-384 MHz band to the VLITE CPU-based correlator. Initial goals included exploring the scientific potential of a commensal low frequency system for ionospheric remote sensing, astrophysics and transients. VLITE operates at nearly 70% wall time with roughly 6200 hours of VLA time recorded each year.Several papers at this meeting review VLITE science and early results. Here we consider how the project could evolve in the future. Over the next 10 years, a straightforward evolutionary path calls for an expansion of VLITE to all 27 VLA antennas and to the maximum available low band receiver bandwidth (224-480 MHz). The GPU-based correlator for this LOw Band Observatory (LOBO) would also incorporate lower frequency signals from the new VLA 74 MHz system, including from VLA dishes (60-80 MHz) and standalone Long Wavelength Array (LWA) aperture array stations (20-80 MHz).In the longer term, we look towards leveraging the vast infrastructure of the ngVLA to include a commensal low frequency capability, called ngLOBO. As described in our community white paper (Taylor et al. 2018; arXiv:1708.00090), ngLOBO has three primary scientific missions: (1) Radio Large Synoptic Survey Telescope (Radio-LSST): one naturally wide beam, commensal with ngVLA, will conduct a continuous synoptic survey of large swaths of the sky for both slow and fast transients; (2) This same commensal beam will provide complementary low frequency images of all ngVLA targets when such data enhances their value. (3) Independent beams from the ng

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.

318-MHz variability of complete samples of extragalactic radio sources. II

International Nuclear Information System (INIS)

Dennison, B.; Broderick, J.J.; Ledden, J.E.; O'Dell, S.L.; Condon, J.J.

1981-01-01

We report the remainder of two- and three-epoch 318-MHz observations of extragalactic sources in samples complete to 3 Jy at 1400 MHz and 1 Jy at 5000 MHz. From analysis of this low-frequency variability survey, we find that steep-spectrum (α> or =0.5) sources do not appear to vary, but about 40% of all flat-spectrum (α<0.5) sources exhibit low-frequency variability exceeding 8% over approx.5 yr. Among the flat-spectrum sources, those with inverted spectra show the largest fractional variations. We also find that the incidence of low-frequency variability is strongly correlated with the determination that a source is an optically violent variable. These statistical properties are consistent with models invoking relativistic beaming of radio and optical emission

Low-noise wide-band amplifiers for stochastic beam cooling experiments

International Nuclear Information System (INIS)

Leskovar, B.; Lo, C.C.

1982-01-01

Noise characteristics of the continuous-wave wide-band amplifier systems for stochastic beam cooling experiments are presented. Also, the noise performance, bandwidth capability and gain stability of components used in these amplifiers are summarized and compared in the 100 MHz to 40 GHz frequency range. This includes bipolar and field-effect transistors, parametric amplifier, Schottky diode mixer and maser. Measurements of the noise characteristics and scattering parameters of variety GaAs FETs as a function of ambient temperature are also given. Performance data and design information are presented on a broadband 150-500 MHz preamplifier having noise temperature of approximately 35 0 K at ambient temperature of 20 0 K. An analysis of preamplifier stability based on scattering parameters concept is included

Effects of corrugation shape on frequency band-gaps for longitudinal wave motion in a periodic elastic layer

DEFF Research Database (Denmark)

Sorokin, Vladislav

2016-01-01

The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band-gaps are det......The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band......, harmonic in the corrugation series. The revealed insights into the mechanism of band-gap formation can be used to predict locations and widths of all frequency band-gaps featured by any corrugation shape. These insights are general and can be valid also for other types of wave motion in periodic structures...

Atmospheric and Fog Effects on Ultra-Wide Band Radar Operating at Extremely High Frequencies.

Science.gov (United States)

Balal, Nezah; Pinhasi, Gad A; Pinhasi, Yosef

2016-05-23

The wide band at extremely high frequencies (EHF) above 30 GHz is applicable for high resolution directive radars, resolving the lack of free frequency bands within the lower part of the electromagnetic spectrum. Utilization of ultra-wideband signals in this EHF band is of interest, since it covers a relatively large spectrum, which is free of users, resulting in better resolution in both the longitudinal and transverse dimensions. Noting that frequencies in the millimeter band are subjected to high atmospheric attenuation and dispersion effects, a study of the degradation in the accuracy and resolution is presented. The fact that solid-state millimeter and sub-millimeter radiation sources are producing low power, the method of continuous-wave wideband frequency modulation becomes the natural technique for remote sensing and detection. Millimeter wave radars are used as complementary sensors for the detection of small radar cross-section objects under bad weather conditions, when small objects cannot be seen by optical cameras and infrared detectors. Theoretical analysis for the propagation of a wide "chirped" Frequency-Modulated Continuous-Wave (FMCW) radar signal in a dielectric medium is presented. It is shown that the frequency-dependent (complex) refractivity of the atmospheric medium causes distortions in the phase of the reflected signal, introducing noticeable errors in the longitudinal distance estimations, and at some frequencies may also degrade the resolution.

Cambridge observations at 38-115 MHz and their implications for space astronomy

International Nuclear Information System (INIS)

Saunders, R.

1987-01-01

The design and performance of the Cambridge LF telescopes are reviewed. Consideration is given to the 151-MHz 6C telescope, the 38-MHz and 151-MHz LF synthesis telescopes, 81.5-MHz interplanetary scintillation observations with the 3.6-hectare array, long-baseline interferometry at 81.5 MHz, and the use of the Jodrell Bank MERLIN for 151-MHz closure-phase observations of bright sources. The strict limitation on the field mappable at a given resolution in ground-based observations at these frequencies is pointed out, and some outstanding astronomical problems requiring 0.3-30-MHz space observations are listed. 7 references

Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

Science.gov (United States)

Simons, Rainee N.; Wintucky, Edwin G.

2016-01-01

This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

Relationships between electroencephalographic spectral peaks across frequency bands

Directory of Open Access Journals (Sweden)

Sacha Jennifer Van Albada

2013-03-01

Full Text Available The degree to which electroenencephalographic (EEG spectral peaks are independent, and the relationships between their frequencies have been debated. A novel fitting method was used to determine peak parameters in the range 2–35 Hz from a large sample of eyes-closed spectra, and their interrelationships were investigated. Findings were compared with a mean-field model of thalamocortical activity, which predicts near-harmonic relationships between peaks. The subject set consisted of 1424 healthy subjects from the Brain Resource International Database. Peaks in the theta range occurred on average near half the alpha peak frequency, while peaks in the beta range tended to occur near twice and three times the alpha peak frequency on an individual-subject basis. Moreover, for the majority of subjects, alpha peak frequencies were significantly positively correlated with frequencies of peaks in the theta and low and high beta ranges. Such a harmonic progression agrees semiquantitatively with theoretical predictions from the mean-field model. These findings indicate a common or analogous source for different rhythms, and help to define appropriate individual frequency bands for peak identification.

Relationships between Electroencephalographic Spectral Peaks Across Frequency Bands

Science.gov (United States)

van Albada, S. J.; Robinson, P. A.

2013-01-01

The degree to which electroencephalographic spectral peaks are independent, and the relationships between their frequencies have been debated. A novel fitting method was used to determine peak parameters in the range 2–35 Hz from a large sample of eyes-closed spectra, and their interrelationships were investigated. Findings were compared with a mean-field model of thalamocortical activity, which predicts near-harmonic relationships between peaks. The subject set consisted of 1424 healthy subjects from the Brain Resource International Database. Peaks in the theta range occurred on average near half the alpha peak frequency, while peaks in the beta range tended to occur near twice and three times the alpha peak frequency on an individual-subject basis. Moreover, for the majority of subjects, alpha peak frequencies were significantly positively correlated with frequencies of peaks in the theta and low and high beta ranges. Such a harmonic progression agrees semiquantitatively with theoretical predictions from the mean-field model. These findings indicate a common or analogous source for different rhythms, and help to define appropriate individual frequency bands for peak identification. PMID:23483663

Frequency scaling of linear super-colliders

International Nuclear Information System (INIS)

Mondelli, A.; Chernin, D.; Drobot, A.; Reiser, M.; Granatstein, V.

1986-06-01

The development of electron-positron linear colliders in the TeV energy range will be facilitated by the development of high-power rf sources at frequencies above 2856 MHz. Present S-band technology, represented by the SLC, would require a length in excess of 50 km per linac to accelerate particles to energies above 1 TeV. By raising the rf driving frequency, the rf breakdown limit is increased, thereby allowing the length of the accelerators to be reduced. Currently available rf power sources set the realizable gradient limit in an rf linac at frequencies above S-band. This paper presents a model for the frequency scaling of linear colliders, with luminosity scaled in proportion to the square of the center-of-mass energy. Since wakefield effects are the dominant deleterious effect, a separate single-bunch simulation model is described which calculates the evolution of the beam bunch with specified wakefields, including the effects of using programmed phase positioning and Landau damping. The results presented here have been obtained for a SLAC structure, scaled in proportion to wavelength

Design of an S band narrow-band bandpass BAW filter

Science.gov (United States)

Gao, Yang; Zhao, Kun-li; Han, Chao

2017-11-01

An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss - 1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designed for potential UAV measurement and control applications. According to the design specifications, the design is as follows: each FBAR's stack was designed in BAW filter by using Mason model. Each FBAR's shape was designed with the method of apodization electrode. The layout of BAW filter was designed. The acoustic-electromagnetic cosimulation model was built to validate the performance of the designed BAW filter. The presented design procedure is a common one, and there are two characteristics: 1) an A and EM co-simulation method is used for the final BAW filter performance validation in the design stage, thus ensures over-optimistic designs by the bare 1D Mason model are found and rejected in time; 2) An in-house developed auto-layout method is used to get compact BAW filter layout, which simplifies iterative error-and-try work here and output necessary in-plane geometry information to the A and EM cosimulation model.

Use of the SAR (Synthetic Aperture Radar) P band for detection of the Moche and Lambayeque canal networks in the Apurlec region, Perù

Science.gov (United States)

Ilaria Pannaccione Apa, Maria; Santovito, Maria Rosaria; Pica, Giulia; Catapano, Ilaria; Fornaro, Gianfranco; Lanari, Riccardo; Soldovieri, Francesco; Wester La Torre, Carlos; Fernandez Manayalle, Marco Antonio; Longo, Francesco; Facchinetti, Claudia; Formaro, Roberto

2016-04-01

In recent years, research attention has been devoted to the development of a new class of airborne radar systems using low frequency bands ranging from VHF/UHF to P and L ones. In this frame, the Italian Space Agency (ASI) has promoted the development of a new multi-mode and multi-band airborne radar system, which can be considered even a "proof-of-concept" for the next space-borne missions. In particular, in agreement with the ASI, the research consortium CO.RI.S.T.A. has in charge the design, development and flight validation of such a kind of system, which is the first airborne radar entirely built in Italy. The aim was to design and realize a radar system able to work in different modalities as: nadir-looking sounder at VHF band (163 MHz); side-looking imager (SAR) at P band with two channels at 450 MHz and 900 MHz. The P-band is a penetration radar. Exploiting penetration features of low frequency electromagnetic waves, dielectric discontinuities of observed scene due to inhomogeneous materials rise up and can be detected on the resulting image. Therefore buried objects or targets placed under vegetation may be detected. Penetration capabilities essentially depend on microwave frequency. Typically, penetration distance is inversely proportional to microwave frequency. The higher the frequency, the lower the penetration depth. Terrain characteristics affect penetration capabilities. Humidity acts as a shield to microwave penetration. Hence terrain with high water content are not good targets for P-band applicability. Science community, governments and space agencies have increased their interest about low frequency radar for their useful applicability in climatology, ecosystem monitoring, glaciology, archaeology. The combination of low frequency and high relative bandwidth of such a systems has a large applicability in both military and civilian applications, ranging from forestry applications, biomass measuring, archaeological and geological exploration

A compact 500 MHz 4 kW Solid-State Power Amplifier for accelerator applications

Energy Technology Data Exchange (ETDEWEB)

Gaspar, M., E-mail: marcos.gaspar@psi.c [Paul Scherrer Institute, CH 5232 Villigen PSI (Switzerland); Pedrozzi, M. [Paul Scherrer Institute, CH 5232 Villigen PSI (Switzerland); Ferreira, L.F.R. [Department of Physics, University of Coimbra, 3004-516 Coimbra (Portugal); Garvey, T. [Paul Scherrer Institute, CH 5232 Villigen PSI (Switzerland)

2011-05-01

We present the development of a compact narrow-band Solid-State Power Amplifier (SSPA). We foresee a promising application of solid-state amplifiers specifically in accelerators for new generation synchrotron light sources. Such a new technology has reached a competitive price/performance ratio and expected lifetime in comparison with klystron and IOT amplifiers. The increasing number of synchrotron light sources using 500 MHz as base frequency justifies the effort in the development of the proposed amplifier. Two different techniques are also proposed to improve the control and performance of these new distributed amplification systems which we call, respectively, complete distributed system and forced compression.

A compact 500 MHz 4 kW Solid-State Power Amplifier for accelerator applications

International Nuclear Information System (INIS)

Gaspar, M.; Pedrozzi, M.; Ferreira, L.F.R.; Garvey, T.

2011-01-01

We present the development of a compact narrow-band Solid-State Power Amplifier (SSPA). We foresee a promising application of solid-state amplifiers specifically in accelerators for new generation synchrotron light sources. Such a new technology has reached a competitive price/performance ratio and expected lifetime in comparison with klystron and IOT amplifiers. The increasing number of synchrotron light sources using 500 MHz as base frequency justifies the effort in the development of the proposed amplifier. Two different techniques are also proposed to improve the control and performance of these new distributed amplification systems which we call, respectively, complete distributed system and forced compression.

162.5 MHz digital low-level radio frequency control monitoring system design and implementation

International Nuclear Information System (INIS)

Zhang Ruifeng; Wang Xianwu; Xu Zhe; Yi Xiaoping

2014-01-01

162.5 MHz high-frequency low-level control system self-developed by Institute of Modern Physics for ADS project took digital technology. All parameters' reading and writing, including loop parameter setting, open and close-loop operation, and condition monitoring, were achieved through the monitoring system. The system used lightweight client-server working mode that client running in the PC sent command data, server running on high-frequency digital low level system responded instructions to complete parameter monitoring and control. The system consisted of three parts. Firstly, server hardware system was constructed based on Atera Stratix Ⅲ family of field-programmable gate array (FPGA) development board. Secondly, the server software system was designed based on Micro C/OS Ⅱ real-time operating systems and lightweight TCP/IP protocol stack, and finally a client PC program was designed based on MFC. After a long test, it was indicated that the monitoring system works properly and stably. TCP sends and receives throughput reached 11.931038 Mbps and 8.117624 Mbps. (authors)

High-frequency response and the possibilities of frequency-tunable narrow-band terahertz amplification in resonant tunneling nanostructures

International Nuclear Information System (INIS)

Kapaev, V. V.; Kopaev, Yu. V.; Savinov, S. A.; Murzin, V. N.

2013-01-01

The characteristics of the high-frequency response of single- and double-well resonant tunneling structures in a dc electric field are investigated on the basis of the numerical solution of a time-dependent Schrödinger equation with open boundary conditions. The frequency dependence of the real part of high frequency conductivity (high-frequency response) in In 0.53 Ga 0.47 As/AlAs/InP structures is analyzed in detail for various values of the dc voltage V dc in the negative differential resistance (NDR) region. It is shown that double-well three-barrier structures are promising for the design of terahertz-band oscillators. The presence of two resonant states with close energies in such structures leads to a resonant (in frequency) response whose frequency is determined by the energy difference between these levels and can be controlled by varying the parameters of the structure. It is shown that, in principle, such structures admit narrow-band amplification, tuning of the amplification frequency, and a fine control of the amplification (oscillation) frequency in a wide range of terahertz frequencies by varying a dc electric voltage applied to the structure. Starting from a certain width of the central intermediate barrier in double-well structures, one can observe a collapse of resonances, where the structure behaves like a single-well system. This phenomenon imposes a lower limit on the oscillation frequency in three-barrier resonant tunneling structures.

Investigation on acceptable reverberation time at various frequency bands in halls that present amplified music

DEFF Research Database (Denmark)

Adelman-Larsen, Niels Werner; Jeong, Cheol-Ho; Støfringsdal, Bård

2018-01-01

Subjective ratings from 25 professional musicians and sound engineers were obtained to assess two Danish rock venues of similar size and similar low frequency reverberation times, but different high frequency reverberation times. The musicians judged one hall significantly better than the other......, confirming a hypothesis that rock venues can have a longer reverberation time at mid to high frequencies at least in the empty condition. A fairly long reverberation time in the 63 Hz octave band is found to be acceptable, so the 125 Hz octave band is probably the single most important band to control...... for amplified music....

Low frequency phononic band structures in two-dimensional arc-shaped phononic crystals

International Nuclear Information System (INIS)

Xu, Zhenlong; Wu, Fugen; Guo, Zhongning

2012-01-01

The low frequency phononic band structures of two-dimensional arc-shaped phononic crystals (APCs) were studied by the transfer matrix method in cylindrical coordinates. The results showed the first phononic band gaps (PBGs) of APCs from zero Hz with low modes. Locally resonant (LR) gaps were obtained with higher-order rotation symmetry, due to LR frequencies corresponding to the speeds of acoustic waves in the materials. These properties can be efficiently used in a structure for low frequencies that are forbidden, or in a device that permits a narrow window of frequencies. -- Highlights: ► We report a new class of quasi-periodic hetero-structures, arc-shaped phononic crystals (APCs). ► The results show the first PBGs start with zero Hz with low modes. ► Locally resonant (LR) gaps were obtained with higher-order rotation symmetry, due to LR frequencies corresponding to the speeds of acoustic waves in the materials.

Computational dosimetry in embryos exposed to electromagnetic plane waves over the frequency range of 10 MHz-1.5 GHz

International Nuclear Information System (INIS)

Kawai, Hiroki; Nagaoka, Tomoaki; Watanabe, Soichi; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi

2010-01-01

This paper presents calculated specific absorption rate (SAR) dosimetry in 4 and 8 week Japanese pregnant-woman models exposed to plane waves over the frequency range of 10 MHz-1.5 GHz. Two types of 2 mm spatial-resolution pregnant-woman models comprised a woman model, which is similar to the average-sized Japanese adult female in height and weight, with a cubic (4 week) embryo or spheroidal (8 week) one. The averaged SAR in the embryos exposed to vertically and horizontally polarized plane waves at four kinds of propagation directions are calculated from 10 MHz to 1.5 GHz. The results indicate that the maximum average SAR in the embryos exposed to plane waves is lower than 0.08 W kg -1 when the incident power density is at the reference level of ICNIRP guideline for general public environment. (note)

1950MHz Radio Frequency Electromagnetic Radiation Inhibits Testosterone Secretion of Mouse Leydig Cells.

Science.gov (United States)

Lin, Yan-Yun; Wu, Tao; Liu, Jun-Ye; Gao, Peng; Li, Kang-Chu; Guo, Qi-Yan; Yuan, Meng; Lang, Hai-Yang; Zeng, Li-Hua; Guo, Guo-Zhen

2017-12-23

More studies that are focused on the bioeffects of radio-frequency (RF) electromagnetic radiation that is generated from the communication devices, but there were few reports with confirmed results about the bioeffects of RF radiation on reproductive cells. To explore the effects of 1950 MHz RF electromagnetic radiation (EMR) on mouse Leydig (TM3) cells. TM3 cells were irradiated or sham-irradiated continuously for 24 h by the specific absorption rate (SAR) 3 W/kg radiation. At 0, 1, 2, 3, 4, and 5 days after irradiation, cell proliferation was detected by cell counting kit-8 (CCK-8) method, cell cycle distribution, percentage of apoptosis, and cellular reactive oxygen species (ROS) were examined by flow cytometry, Testosterone level was measured using enzyme-linked immunosorbent assay (ELISA) assay, messenger ribonucleic acid (mRNA) expression level of steroidogenic acute regulatory protein (StAR) and P450scc in TM3 cells was detected by real-time polymerase chain reaction (PCR). After being irradiated for 24 h, cell proliferation obviously decreased and cell cycle distribution, secretion capacity of Testosterone, and P450scc mRNA level were reduced. While cell apoptosis, ROS, and StAR mRNA level did not change significantly. The current results indicated that 24 h of exposure at 1950 MHz 3 W/kg radiation could cause some adverse effects on TM3 cells proliferation and Testosterone secretion, further studies about the biological effects in the reproductive system that are induced by RF radiation are also needed.

Investigation on the performance of an optically generated RF local oscillator signal in Ku-band DVB-S systems

NARCIS (Netherlands)

Khan, M.R.H.; Marpaung, D.A.I.; Burla, M.; Roeloffzen, C.G.H.; Bernhardi, Edward; de Ridder, R.M.

2011-01-01

We investigate a way to externally generate the local oscillator (LO) signal used for downconversion of the Ku-band (10.7 − 12.75 GHz) RF signal received from a phased array antenna (PAA). The signal is then translated to an intermediate frequency (950 − 2150 MHz) at the output of the mixer of

Wide band ENDOR spectrometer

International Nuclear Information System (INIS)

Mendonca Filho, C.

1973-01-01

The construction of an ENDOR spectrometer operating from 0,5 to 75 MHz within a single band, with ore Klystron and homodine detection, and no fundamental changes on the electron spin resonance spectrometer was described. The ENDOR signal can be detected both by amplitude modulation of the frequency field, or direct detection of the ESR output, which is taken to a signal analyser. The signal-to-noise ratio is raised by averaging rather than filtering avoiding the use of long time constants, providing natural line widths. The experimental apparatus and the spectra obtained are described. A discussion, relating the ENDOR line amplitudes with the experimental conditions is done and ENDOR mechanism, in which there is a relevant presence of cross relaxation is proposed

Solar observations with a low frequency radio telescope

Science.gov (United States)

Myserlis, I.; Seiradakis, J.; Dogramatzidis, M.

2012-01-01

We have set up a low frequency radio monitoring station for solar bursts at the Observatory of the Aristotle University in Thessaloniki. The station consists of a dual dipole phased array, a radio receiver and a dedicated computer with the necessary software installed. The constructed radio receiver is based on NASA's Radio Jove project. It operates continuously, since July 2010, at 20.1 MHz (close to the long-wavelength ionospheric cut-off of the radio window) with a narrow bandwidth (~5 kHz). The system is properly calibrated, so that the recorded data are expressed in antenna temperature. Despite the high interference level of an urban region like Thessaloniki (strong broadcasting shortwave radio stations, periodic experimental signals, CBs, etc), we have detected several low frequency solar radio bursts and correlated them with solar flares, X-ray events and other low frequency solar observations. The received signal is monitored in ordinary ASCII format and as audio signal, in order to investigate and exclude man-made radio interference. In order to exclude narrow band interference and calculate the spectral indices of the observed events, a second monitoring station, working at 36 MHz, is under construction at the village of Nikiforos near the town of Drama, about 130 km away of Thessaloniki. Finally, we plan to construct a third monitoring station at 58 MHz, in Thessaloniki. This frequency was revealed to be relatively free of interference, after a thorough investigation of the region.

Low band gap frequencies and multiplexing properties in 1D and 2D mass spring structures

International Nuclear Information System (INIS)

Aly, Arafa H; Mehaney, Ahmed

2016-01-01

This study reports on the propagation of elastic waves in 1D and 2D mass spring structures. An analytical and computation model is presented for the 1D and 2D mass spring systems with different examples. An enhancement in the band gap values was obtained by modeling the structures to obtain low frequency band gaps at small dimensions. Additionally, the evolution of the band gap as a function of mass value is discussed. Special attention is devoted to the local resonance property in frequency ranges within the gaps in the band structure for the corresponding infinite periodic lattice in the 1D and 2D mass spring system. A linear defect formed of a row of specific masses produces an elastic waveguide that transmits at the narrow pass band frequency. The frequency of the waveguides can be selected by adjusting the mass and stiffness coefficients of the materials constituting the waveguide. Moreover, we pay more attention to analyze the wave multiplexer and DE-multiplexer in the 2D mass spring system. We show that two of these tunable waveguides with alternating materials can be employed to filter and separate specific frequencies from a broad band input signal. The presented simulation data is validated through comparison with the published research, and can be extended in the development of resonators and MEMS verification. (paper)

A low-power RF system with accurate synchronization for a S-band RF-gun using a laser-triggered photocathode

International Nuclear Information System (INIS)

Otake, Y.; Naito, T.; Shintake, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

1992-01-01

An S-band RF-gun using a laser-triggered photocathode and its low-power RF system have been constructed. The main elements of the low-power RF system comprise a 600-W amplifier, an amplitude modulator, a phase detector, a phase shifter and a frequency-divider module. Synchronization between the RF fields for acceleration and the mode-locked laser pulses for beam triggering are among the important points concerning the RF-gun. The frequency divider module which down-converts from 2856 MHz(RF) to 89.25 MHz(laser), and the electrical phase-shifter were specially developed for stable phase control. The phase jitter of the frequency divider should be less than 10 ps to satisfy our present requirements. The first experiments to trigger and accelerate beams with the above-mentioned system were carried out in January, 1992. (Author) 6 figs., 5 refs

Measuring personal exposure from 900MHz mobile phone base stations in Australia and Belgium using a novel personal distributed exposimeter.

Science.gov (United States)

Bhatt, Chhavi Raj; Thielens, Arno; Redmayne, Mary; Abramson, Michael J; Billah, Baki; Sim, Malcolm R; Vermeulen, Roel; Martens, Luc; Joseph, Wout; Benke, Geza

2016-01-01

The aims of this study were to: i) measure personal exposure in the Global System for Mobile communications (GSM) 900MHz downlink (DL) frequency band with two systems of exposimeters, a personal distributed exposimeter (PDE) and a pair of ExpoM-RFs, ii) compare the GSM 900MHz DL exposures across various microenvironments in Australia and Belgium, and iii) evaluate the correlation between the PDE and ExpoM-RFs measurements. Personal exposure data were collected using the PDE and two ExpoM-RFs simultaneously across 34 microenvironments (17 each in Australia and Belgium) located in urban, suburban and rural areas. Summary statistics of the electric field strengths (V/m) were computed and compared across similar microenvironments in Australia and Belgium. The personal exposures across urban microenvironments were higher than those in the rural or suburban microenvironments. Likewise, the exposure levels across the outdoor were higher than those for indoor microenvironments. The five highest median exposure levels were: city centre (0.248V/m), bus (0.124V/m), railway station (0.105V/m), mountain/forest (rural) (0.057V/m), and train (0.055V/m) [Australia]; and bicycle (urban) (0.238V/m), tram station (0.238V/m), city centre (0.156V/m), residential outdoor (urban) (0.139V/m) and park (0.124V/m) [Belgium]. Exposures in the GSM900 MHz frequency band across most of the microenvironments in Australia were significantly lower than the exposures across the microenvironments in Belgium. Overall correlations between the PDE and the ExpoM-RFs measurements were high. The measured exposure levels were far below the general public reference levels recommended in the guidelines of the ICNIRP and the ARPANSA. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Improved estimation of leak location of pipelines using frequency band variation

Energy Technology Data Exchange (ETDEWEB)

Lee, Young Sup [Embedded System Engineering Department, Incheon National University, Incheon (Korea, Republic of); Yoon, Dong Jin [Safety Measurement Center, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2014-02-15

Leakage is an important factor to be considered for the management of underground water supply pipelines in a smart water grid system, especially if the pipelines are aged and buried under the pavement or various structures of a highly populated city. Because the exact detection of the location of such leaks in pipelines is essential for their efficient operation, a new methodology for leak location detection based on frequency band variation, windowing filters, and probability is proposed in this paper. Because the exact detection of the leak location depends on the precision of estimation of time delay between sensor signals due to leak noise, some window functions that offer weightings at significant frequencies are applied for calculating the improved cross-correlation function. Experimental results obtained by applying this methodology to an actual buried water supply pipeline, ∼ 253.9 m long and made of cast iron, revealed that the approach of frequency band variation with those windows and probability offers better performance for leak location detection.

Improved estimation of leak location of pipelines using frequency band variation

International Nuclear Information System (INIS)

Lee, Young Sup; Yoon, Dong Jin

2014-01-01

Leakage is an important factor to be considered for the management of underground water supply pipelines in a smart water grid system, especially if the pipelines are aged and buried under the pavement or various structures of a highly populated city. Because the exact detection of the location of such leaks in pipelines is essential for their efficient operation, a new methodology for leak location detection based on frequency band variation, windowing filters, and probability is proposed in this paper. Because the exact detection of the leak location depends on the precision of estimation of time delay between sensor signals due to leak noise, some window functions that offer weightings at significant frequencies are applied for calculating the improved cross-correlation function. Experimental results obtained by applying this methodology to an actual buried water supply pipeline, ∼ 253.9 m long and made of cast iron, revealed that the approach of frequency band variation with those windows and probability offers better performance for leak location detection.

Analysis of Electromagnetic Propagation from MHz to THz with a Memory-Optimised CPML-FDTD Algorithm

Directory of Open Access Journals (Sweden)

A. Rodríguez-Sánchez

2018-01-01

Full Text Available FDTD method opened a fertile research area on the numerical analysis of electromagnetic phenomena under a wide range of media and propagation conditions, providing an extensive analysis of electromagnetic behaviour like propagation, reflection, refraction, and multitrajectory phenomena. In this paper, we present an optimised FDTD-CPML algorithm, focused in saving memory while increasing the performance of the algorithm. We particularly implement FDTD-CPML method at high frequency bands, used in several telecommunications applications as well as in nanoelectromagnetism. We show an analysis of the performance of the algorithm in single and double precision, as well as a stability of the algorithm analysis, from where we conclude that the implemented CPML ABC constitutes a robust choice in terms of precision and accuracy for the high frequencies herein considered. It is important to recall that the CPML ABC parameters provided in this paper are fixed for the tested range of frequencies, that is, from MHz to THz.

Strong RFI observed in protected 21 cm band at Zurich observatory, Switzerland

Science.gov (United States)

Monstein, C.

2014-03-01

While testing a new antenna control software tool, the telescope was moved to the most western azimuth position pointing to our own building. While de-accelerating the telescope, the spectrometer showed strong broadband radio frequency interference (RFI) and two single-frequency carriers around 1412 and 1425 MHz, both of which are in the internationally protected band. After lengthy analysis it was found out, that the Webcam AXIS2000 was the source for both the broadband and single-frequency interference. Switching off the Webcam solved the problem immediately. So, for future observations of 21 cm radiation, all nearby electronics has to be switched off. Not only the Webcam but also all unused PCs, printers, networks, monitors etc.

Magnetoelectric effect in nanogranular FeCo-MgF films at GHz frequencies

Science.gov (United States)

Ikeda, Kenji; Kobayashi, Nobukiyo; Arai, Ken-Ichi; Yabukami, Shin

2018-01-01

The magnetoelectric effect is a key issue for material science and is particularly significant in the high frequency band, where it is indispensable in industrial applications. Here, we present for the first time, a study of the high frequency tunneling magneto-dielectric (TMD) effect in nanogranular FeCo-MgF films, consisting of nanometer-sized magnetic FeCo granules dispersed in an MgF insulator matrix. Dielectric relaxation and the TMD effect are confirmed at frequencies over 10 MHz. The frequency dependence of dielectric relaxation is described by the Debye-Fröhlich model, taking relaxation time dispersion into account, which reflects variations in the nature of the microstructure, such as granule size, and the inter-spacing between the granules that affect the dielectric response. The TMD effect reaches a maximum at a frequency that is equivalent to the inverse of the relaxation time. The frequency where the peak TMD effect is observed varies between 12 MHz and 220 MHz, depending on the concentration of magnetic metal in the nanogranular films. The inter-spacing of the films decreases with increasing magnetic metal concentration, in accordance with the relaxation time. These results indicate that dielectric relaxation is controlled by changing the nanostructure, using the deposition conditions. A prospective application of these nanogranular films is in tunable impedance devices for next-generation mobile communication systems, at frequencies over 1 GHz, where capacitance is controlled using the applied magnetic field.

Performance analysis of commercial MOSFET packages in Class E converter operating at 2.56 MHz

DEFF Research Database (Denmark)

Nair, Unnikrishnan Raveendran; Munk-Nielsen, Stig; Jørgensen, Asger Bjørn

2017-01-01

resistance and high temperature operation over Si devices have aided in the paradigm shift towards wide bandgap devices. The low gate charge requirements of SiC MOSFETs enables use of these devices in radio frequency (RF) converters using resonant topologies operating at MHz frequency range. The RF...... are not commercially available and power modules have to be custom designed for these applications. This work demonstrates performance of various commercial MOSFET packages at frequency of 2.56 MHz. Commercial SiC MOSFETs in TO-247 and D2Pak packs are tested in Class E resonant converter operating at 2.56 MHz...

JNDS of interaural time delay (ITD) of selected frequency bands in speech and music signals

Science.gov (United States)

Aliphas, Avner; Colburn, H. Steven; Ghitza, Oded

2002-05-01

JNDS of interaural time delay (ITD) of selected frequency bands in the presence of other frequency bands have been reported for noiseband stimuli [Zurek (1985); Trahiotis and Bernstein (1990)]. Similar measurements will be reported for speech and music signals. When stimuli are synthesized with bandpass/band-stop operations, performance with complex stimuli are similar to noisebands (JNDS in tens or hundreds of microseconds); however, the resulting waveforms, when viewed through a model of the auditory periphery, show distortions (irregularities in phase and level) at the boundaries of the target band of frequencies. An alternate synthesis method based upon group-delay filtering operations does not show these distortions and is being used for the current measurements. Preliminary measurements indicate that when music stimuli are created using the new techniques, JNDS of ITDs are increased significantly compared to previous studies, with values on the order of milliseconds.

47 CFR 80.303 - Watch on 156.800 MHz (Channel 16).

Science.gov (United States)

2010-10-01

... Section 80.303 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Safety Watch Requirements and Procedures Coast Station Safety... maintain a safety watch on the frequency 156.800 MHz except when transmitting on 156.800 MHz. (b) A coast...

75 FR 29677 - PLMR Licensing; Frequency Coordination and Eligibility Issues

Science.gov (United States)

2010-05-27

... in the portions of the 1427-1432 MHz band where non- medical telemetry has primary status. We take... free of harmful interference. The band 1427-1432 MHz is shared between medical and non-medical telemetry operations. Generally, WMTS has primary status in the lower half of the band, and non-medical...

75 FR 9210 - Wireless Telecommunications Bureau Seeks Comment on Petition for Rulemaking Regarding 700 MHz...

Science.gov (United States)

2010-03-01

[email protected] or call the Consumer & Governmental Affairs Bureau at 202-418-0530 (Voice), 202-418-0432 (TTY... the Commission to ``assure that consumers will have access to all paired 700 MHz spectrum that the Commission licenses, to act so that the entire 700 MHz band will develop in a competitive fashion, and to...

Transistorized wide band pulse amplifier; Amplificateur d'impulsions a large bande et a transistors

Energy Technology Data Exchange (ETDEWEB)

Girard, J; Savinelli, H [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Hazoni, Y [Atomic Energy Commission (Israel)

1960-07-01

A simple wide band amplifier is described below, having a stability better than 1{sup 0}/00 deg{sup -1} centigrade, a current gain of 10{sup 3}, bandwidth of 30 MHz, and a signal to noise current ratio of about 100. This amplifier has been studied to answer the necessity of a fast transistor head amplifier for nuclear detectors, having in mind pile up and overloading problems. (author) [French] Un amplificateur simple, a large bande, est decrit ci-apres, il a une stabilite meilleure que le 0/00 par degre centigrade, un gain en courant de 10{sup 3} une largeur de bande de 30 MHz, et un rapport signal sur bruit en courant d'environ 100. Cet amplificateur a ete etudie pour repondre a la necessite de l'amplification des impulsions provenant de detecteurs nucleaires, ayant a l'esprit les problemes d'empilement et de saturation. (auteur)

Two frequency ICRF operation on TFTR

International Nuclear Information System (INIS)

Rogers, J.H.; Majeski, R.; Wilson, J.R.; Hosea, J.C.; Schilling, G.; Stevens, J.; Phillips, C.K.

1993-01-01

Modifications have been made recently to allow two of the ICRF antennas (bays L and M) on TFTR to operate at either of two frequencies, 43 MHz or 64 MHz. This was accomplished by lengthening the resonant loops (2Λ at 43 MHz, 3Λ at 64 MHz) and replacing the conventional quarter wave impedance transformers with a tapered impedance design. The other two antennas (bays K and N) will operate at a fixed frequency, 43 MHz. The two frequency operation will allow a combination of 3 He-minority and H-minority heating at near full field on TFTR. The higher frequency, 64 MHz, may also be useful in direct electron heating and current drive experiments at lower toroidal fields. Models of the antenna, resonant loops and impedance matching system are presented

Magnetic fields of AM band radio broadcast signals at the Richmond Field Station

International Nuclear Information System (INIS)

Becker, Alex; Frangos, William

1998-01-01

Non-invasive sensing of the shallow subsurface is necessary for detection and delineation of buried hazardous wastes, monitoring of the condition of clay containment caps, and a variety of other purposes. Electromagnetic methods have proven to be effective in environmental site characterization where there is a need for increased resolution in subsurface characterization. Two considerations strongly suggest the use of frequencies between 100 kHz and 100 MHz for such applications: 1) the induction response of many targets is small due to small size, and 2) a need to determine both the electrical conductivity and dielectric permittivity which are related to chemistry and hydrology. Modeling and physical parameter studies confirm that measurements at frequencies between 1 and 100 MHz can resolve variations in subsurface conductivity and permittivity. To provide the necessary technology for shallow subsurface investigations, we propose to exploit the concept of electromagnetic impedance, the ratio of orthogonal horizontal electric and magnetic fields. Prior to assembling the equipment for measuring surface impedance using controlled, local source it was felt prudent to measure the surface impedance of geological materials at the University of California at Berkeley's Richmond Field (RFS) using ambient energy in the broadcast band. As a first step toward this intermediate goal, we have examined and characterized local AM band radio signals in terms of both signal strength and polarization of the magnetic component as received at RFS. In addition, we have established the viability of a commercial radio-frequency magnetic sensor

Proposal of a novel compact P-band magnetically insulated transmission line oscillator with inclined vanes

Science.gov (United States)

Zhang, Xiaoping; Dang, Fangchao; Li, Yangmei; Jin, Zhenxing

2015-06-01

In this paper, we present a novel compact P-band magnetically insulated transmission line oscillator (MILO) with specially inclined slow-wave-structure (SWS) vanes to decrease its total dimension and weight. The dispersion characteristics of the inclined SWS are investigated in detail and made comparisons with that of the traditional straight SWS. The results show that the inclined SWS is more advantageous in operating on a steady frequency in a wide voltage range and has a better asymmetric mode segregation and a relatively large band-gap between the TM00 and TM01 modes which are in favor of avoiding the asymmetric and transverse mode competition. Besides, the transverse dimension of the proposed novel inclined SWS with the same operation frequency is decreased by about 50%, and correspondingly the device volume shrinks remarkably to its 0.35 times. In particle-in-cell simulation, the electron bunching spokes are obviously formed in the inclined SWS, and a P-band high-power microwave with a power of 5.8 GW, frequency of 645 MHz, and efficiency of 17.2% is generated by the proposed device, which indicates the feasibility of the compact design with the inclined vanes at the P-band.

A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits.

Science.gov (United States)

Ikeda, Shigeyuki; Takeuchi, Hikaru; Taki, Yasuyuki; Nouchi, Rui; Yokoyama, Ryoichi; Kotozaki, Yuka; Nakagawa, Seishu; Sekiguchi, Atsushi; Iizuka, Kunio; Yamamoto, Yuki; Hanawa, Sugiko; Araki, Tsuyoshi; Miyauchi, Carlos Makoto; Sakaki, Kohei; Nozawa, Takayuki; Yokota, Susumu; Magistro, Daniele; Kawashima, Ryuta

2017-01-01

Recently, the association between human personality traits and resting-state brain activity has gained interest in neuroimaging studies. However, it remains unclear if Big Five personality traits are represented in frequency bands (~0.25 Hz) of resting-state functional magnetic resonance imaging (fMRI) activity. Based on earlier neurophysiological studies, we investigated the correlation between the five personality traits assessed by the NEO Five-Factor Inventory (NEO-FFI), and the fractional amplitude of low-frequency fluctuation (fALFF) at four distinct frequency bands (slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz) and slow-2 (0.198-0.25 Hz)). We enrolled 835 young subjects and calculated the correlations of resting-state fMRI signals using a multiple regression analysis. We found a significant and consistent correlation between fALFF and the personality trait of extraversion at all frequency bands. Furthermore, significant correlations were detected in distinct brain regions for each frequency band. This finding supports the frequency-specific spatial representations of personality traits as previously suggested. In conclusion, our data highlight an association between human personality traits and fALFF at four distinct frequency bands.

Meandered Monopoles for 700 MHz LTE Handsets and Improved MIMO Channel Capacity Performance

Directory of Open Access Journals (Sweden)

I. Dioum

2011-12-01

Full Text Available In this paper, we present the design and the measurement of MIMO meandered monopole antennas and the computation of their channel capacity performance. The initial proposed handset-system is composed of a meandered monopole operating in the LTE 700 MHz band, connected to a parasitic radiating element for the upper 2.5 GHz LTE band. Two antennas of the same kind are then closely positioned on the same 120x50 mm2 Printed Circuit Board (PCB. A neutralization line connects the two antennas to enhance their port-to-port isolation in the 700 MHz band. The computation of the channel capacity performance in this band is based on propagation simulations performed with the GRIMM model from the CREMANT. Two system-prototypes are evaluated: one with the neutralization line for enhanced port-to-port isolation and a second without the neutralization exhibiting poor antenna-to-antenna isolation. It is demonstrated that the neutralization technique helps in giving a minimum improvement of 12% of the capacity performance of the handset-system, and a maximum improvement 46%, in the chosen environment.

Development of 650 MHz (β=0.9) single-cell SCRF cavity

International Nuclear Information System (INIS)

Bagre, M.; Jain, V.; Yedle, A.; Maurya, T.; Yadav, A.; Puntambekar, A.; Goswami, S.G.; Choudhary, R.S.; Sandha, S.; Dwivedi, J.; Kane, G.V.; Mahawar, A.; Mohania, P.; Shrivastava, P.; Sharma, S.; Gupta, R.; Sharma, S.D.; Joshi, S.C.; Mistri, K.K.; Prakash, P.N.

2013-01-01

Raja Ramanna Centre for Advanced Technology has initiated the work on development of Superconducting Radio Frequency (SCRF) cavities and associated technologies as part of R and D activities for upcoming Spallation Neutron Source (SNS) project involving superconducting Linear Accelerator (LINAC). It is planned to use 650 MHz SCRF cavities for the medium and high energy section of the proposed LINAC. Under Indian Institution Fermilab Collaboration (IIFC), Raja Ramanna Centre for Advanced Technology is also working on development of 650 MHz (β=0.9) SCRF cavities proposed to be used in the high energy section of Project-X at FNAL. The work has been initiated with design and development of 650 MHz single cell SCRF cavity. FE analysis was done to estimate change in frequency with temperature as well as to estimate the frequency of the cavity at different cavity manufacturing stages. The development cycle comprises of design and manufacturing of forming tooling, machining, welding and RF measurement fixtures as well as design for manufacturing. The half-cell and beam tubes forming and machining of all parts were done using in-house facilities. The Electron beam welding was carried out at Inter-University Accelerator Centre (IUAC), New Delhi under a MoU. One 650 MHz single cell SCRF cavity has been recently manufactured. In this paper we present the development efforts on manufacturing and pre-qualification of 650 MHz (β=0.9) single cell SCRF cavity. (author)

78 FR 66298 - Promoting Interoperability in the 700 MHz Commercial Spectrum; Requests for Waiver and Extension...

Science.gov (United States)

2013-11-05

... when the two operators use the same 2G and 3G technologies and bands), and Band Class 12 devices and... Lower 700 MHz band to improve choice and quality for consumers of mobile services. The Commission... an efficient and effective manner to improve choice and quality for consumers of mobile services. A...

Ohmic heating of peaches in the wide range of frequencies (50 Hz to 1 MHz).

Science.gov (United States)

Shynkaryk, Mykola V; Ji, Taehyun; Alvarez, Valente B; Sastry, Sudhir K

2010-09-01

The ohmic heating (OH) rate of peaches was studied at fixed electric field strength of 60 V.cm⁻¹, square-shaped instant reversal bipolar pulses, and frequencies varying within 50 Hz to 1 MHz. Thermal damage of tissue was evaluated from electrical admittivity. It showed that the time for half disruption (τ(T)) of tissue was required more than 10 h at temperatures below 40 °C. However, cellular thermal disruption occurred almost instantly (τ(T) 90 °C). Electrical conductivity σ(o) and admittivity σ(o)* of tissue at T(o)= 0 °C and their temperature coefficients (m, m*) were calculated. For freeze-thawed tissues, σ and σ* as well as m and m* were nearly indifferent to the frequency. However, for the intact tissue, both σ(o), σ(o)* and m, m* were frequency dependent. For freeze-thawed product, the power factor (P) was approximately equal to 1 and indifferent to the frequency and temperature. On the other hand, strong frequency dependence was observed for intact tissue with the minimum P approximately equal to 0.68 in the range of tens of kHz. The time required to reach a target temperature t(f) was evaluated. The t(f) increased with frequency up to the middle of the range of tens of kHz and thereafter continuously decreased. Samples exposed to the low-frequency electric field demonstrated faster electro-thermal damage rates. The textural relaxation data supported more intense damage kinetics at low-frequency OH. It has been demonstrated that a combination of high-frequency OH with pasteurization at moderate temperature followed by rapid cooling minimizes texture degradation of peach tissue. In this study, we investigated the electric field frequency effect on the rate of OH of peaches. It was shown that the time required for reaching the target temperature is strongly dependent upon the frequency. Samples exposed to low-frequency OH demonstrated higher electro-thermal damage rates. It has been shown that the combination of high-frequency OH with

Design of 118 MHz twelfth harmonic cavity of APS PAR

International Nuclear Information System (INIS)

Kang, Y.W.; Kustom, R.L.; Bridges, J.F.

1992-01-01

Two radio frequency (RF) cavities are needed in the Positron Accumulator Ring (PAR) of the Advanced Photon Source. One is for the first harmonic frequency at 9.8 MHz, and the other is for the twelfth harmonic frequency at 118 MHz. This note reports on the design of the 118 MHz RF cavity. Computer models are used to find the mode frequencies, impedances, Q-factors, and field distributions in the cavity. The computer codes MAFIA, URMEL, and URMEL-T are useful tools which model and simulate the resonance characteristics of a cavity. These codes employ the finite difference method to solve Maxwell's equations. MAFIA is a three-dimensional problem solver and uses square patches to approximate the inner surface of a cavity. URMEL and URMEL-T are two-dimensional problem solvers and use rectangular and triangular meshes, respectively. URMEL-T and MAFIA can handle problems with arbitrary dielectric materials located inside the boundary. The cavity employs a circularly cylindrical ceramic window to limit the vacuum to the beam pipe. The ceramic window used in the modeling will have a wall thickness of 0.9 cm. This wall thickness is not negligible in determining the resonant frequencies of the cavity. In the following, results of two- and three-dimensional modeling of the cavities using the URMEL-T and MAFIA codes are reported

A 500-600 MHz GaN power amplifier with RC-LC stability network

Science.gov (United States)

Ma, Xinyu; Duan, Baoxing; Yang, Yintang

2017-08-01

A 500-600 MHz high-efficiency, high-power GaN power amplifier is designed and realized on the basis of the push-pull structure. The RC-LC stability network is proposed and applied to the power amplifier circuit for the first time. The RC-LC stability network can significantly reduce the high gain out the band, which eliminates the instability of the power amplifier circuit. The developed power amplifier exhibits 58.5 dBm (700 W) output power with a 17 dB gain and 85% PAE at 500-600 MHz, 300 μs, 20% duty cycle. It has the highest PAE in P-band among the products at home and abroad. Project supported by the National Key Basic Research Program of China (No. 2014CB339901).

A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits

Directory of Open Access Journals (Sweden)

Shigeyuki Ikeda

2017-06-01

Full Text Available Recently, the association between human personality traits and resting-state brain activity has gained interest in neuroimaging studies. However, it remains unclear if Big Five personality traits are represented in frequency bands (~0.25 Hz of resting-state functional magnetic resonance imaging (fMRI activity. Based on earlier neurophysiological studies, we investigated the correlation between the five personality traits assessed by the NEO Five-Factor Inventory (NEO-FFI, and the fractional amplitude of low-frequency fluctuation (fALFF at four distinct frequency bands (slow-5 (0.01–0.027 Hz, slow-4 (0.027–0.073 Hz, slow-3 (0.073–0.198 Hz and slow-2 (0.198–0.25 Hz. We enrolled 835 young subjects and calculated the correlations of resting-state fMRI signals using a multiple regression analysis. We found a significant and consistent correlation between fALFF and the personality trait of extraversion at all frequency bands. Furthermore, significant correlations were detected in distinct brain regions for each frequency band. This finding supports the frequency-specific spatial representations of personality traits as previously suggested. In conclusion, our data highlight an association between human personality traits and fALFF at four distinct frequency bands.

Ultrasonic flow-through filtration of microparticles in a microfluidic channel using frequency sweep technique

International Nuclear Information System (INIS)

Seo, Dae Cheol; Ahn, Bong Young; Cho, Seung Hyun; Siddique, A. K. M. Ariful Haque; Kim, Cheol Gi

2013-01-01

Many studies have been conducted on the filtration of microparticles using the acoustic radiation force of ultrasonic standing wave. The present work concerns a flow-through particle filtration method by utilizing frequency varying ultrasound. The periodical frequency sweep of the ultrasonic standing wave translocates particles across a microchannel, where particles in fluid flow are filtrated without barriers. The present filtration technique in a microfluidic channel was proposed conceptually in the 1990s. However, its experimental realization on actual particles in a microfluidic channel has not been carried out in a notable way. Several sizes of polystyrene microspheres (10 µm to 90 µm) and silicon carbide (SiC) particles (37 µm) suspended in water were applied as a test sample. For filtration of those particles, a Y-branched microfluidic channel with one inlet and two outlets was made out of steel and acrylic as a form of modulized device. Ultrasound of a few MHz in band frequency (1.75 MHz to 3.05 MHz) was transmitted into one side of the channel wall to generate a standing wave field in fluid flow. The periodical frequency sweep operation showed successful filtration performance, whereby particles in water flowed into one outlet and purified water flowed into the other outlet of the Y branch of the channel.

Crosstalk Models for Short VDSL2 Lines from Measured 30 MHz Data

Directory of Open Access Journals (Sweden)

Leshem A

2006-01-01

Full Text Available In recent years, there has been a growing interest in hybrid fiber-copper access solutions, as in fiber to the basement (FTTB and fiber to the curb/cabinet (FTTC. The twisted pair segment in these architectures is in the range of a few hundred meters, thus supporting transmission over tens of MHz. This paper provides crosstalk models derived from measured data for quad cable, lengths between 75 and 590 meters, and frequencies up to MHz. The results indicate that the log-normal statistical model (with a simple parametric law for the frequency-dependent mean fits well up to MHz for both FEXT and NEXT. This extends earlier log-normal statistical modeling and validation results for NEXT over bandwidths in the order of a few MHz. The fitted crosstalk power spectra are useful for modem design and simulation. Insertion loss, phase, and impulse response duration characteristics of the direct channels are also provided.

Bio-WiTel: A Low-Power Integrated Wireless Telemetry System for Healthcare Applications in 401-406 MHz Band of MedRadio Spectrum.

Science.gov (United States)

Srivastava, Abhishek; Sankar K, Nithin; Chatterjee, Baibhab; Das, Devarshi; Ahmad, Meraj; Kukkundoor, Rakesh Keshava; Saraf, Vivek; Ananthapadmanabhan, Jayachandran; Sharma, Dinesh Kumar; Baghini, Maryam Shojaei

2018-03-01

This paper presents a low-power integrated wireless telemetry system (Bio-WiTel) for healthcare applications in 401-406 MHz frequency band of medical device radiocommunication (MedRadio) spectrum. In this paper, necessary design considerations for telemetry system for short-range (upto 3 m) communication of biosignals are presented. These considerations help greatly in making important design decisions, which eventually lead to a simple, low power, robust, and reliable wireless system implementation. Transmitter (TX) and receiver (RX) of Bio-WiTel system have been fabricated in 180 nm mixed mode CMOS technology. While radiating -18 dBm output power to a 50 antenna, the packaged TX IC consumes 250 μW power in 100% on state from 1 V supply, whereas the RX IC consumes 990 μW power from 1.8 V supply with a sensitivity of -75 dBm. Measurement results show that TX fulfils the spectral mask requirement at a maximum data rate of 72 kb/s. The measured bit error rate (BER) of RX is less than for a data rate of 200 kb/s. The proposed Bio-WiTel system is tested successfully in home and hospital environments for the communication of electrocardiogram and photoplethysmogram signals at a data rate of 57.6 kb/s with a measured BER of <10 for a maximum distance of 3 m.

Modulation of auroral electron fluxes in the frequency range 50 kHz to 10 MHz

Science.gov (United States)

Spiger, R. J.; Murphree, J. S.; Anderson, H. R.; Loewenstein, R. F.

1976-01-01

A sounding rocket-borne electron detector of high time resolution is used to search for modulation of auroral electron fluxes in the frequency range 50 kHz to 10 MHz and energy range 5-7 keV. Data were telemetered to ground via a 93-kHz subcarrier. A cross-correlation analysis of the data collected indicates low-level modulation near the detection threshold of the instrument. Two U-1 events are observed which are interpreted as indications of modulation. The two modulation events occur during a period of increasing flux for a region marking the boundary between two current sheets detected by the payload magnetometer. The strongest argument against interference contamination is the lack of any observable modulation at times other than those mentioned in the study.

A single sensor and single actuator approach to performance tailoring over a prescribed frequency band.

Science.gov (United States)

Wang, Jiqiang

2016-03-01

Restricted sensing and actuation control represents an important area of research that has been overlooked in most of the design methodologies. In many practical control engineering problems, it is necessitated to implement the design through a single sensor and single actuator for multivariate performance variables. In this paper, a novel approach is proposed for the solution to the single sensor and single actuator control problem where performance over any prescribed frequency band can also be tailored. The results are obtained for the broad band control design based on the formulation for discrete frequency control. It is shown that the single sensor and single actuator control problem over a frequency band can be cast into a Nevanlinna-Pick interpolation problem. An optimal controller can then be obtained via the convex optimization over LMIs. Even remarkable is that robustness issues can also be tackled in this framework. A numerical example is provided for the broad band attenuation of rotor blade vibration to illustrate the proposed design procedures. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Influence of 1800 MHz GSM-like electromagnetic radiation exposure on fracture healing.

Science.gov (United States)

Aslan, Ahmet; Kırdemır, Vecihi; Kocak, Ahmet; Atay, Tolga; Baydar, Metin Lütfi; Özerdemoglu, Remzi Arif; Aydogan, Nevres Hürriyet

2014-02-01

In this study, we aimed to investigate whether 1800 MHz frequency electromagnetic radiation (EMR) has an effect on bone healing. A total of 30 Wistar albino rats were divided into two equal groups. Fractures were created in the right tibias of all rats; next, intramedullary fixations with K-wire were performed. A control group (Group I) was kept under the same experimental conditions except without EMR exposure. Rats in Group II were exposed to an 1800 MHz frequency EMR for 30 min a day for 5 days a week. Next, radiological, mechanical, and histological examinations were performed to evaluate tibial fracture healing. Radiological, histological and mechanical scores were not significantly different between groups (respectively, p = 0.114, p = 0.184 and p = 0.083), and all of these scores were lower than those of the controls. EMR at 1800 MHz frequency emitted from cellular phones has no effect on bone fracture healing. Copyright © 2014 IMSS. Published by Elsevier Inc. All rights reserved.

An open-structure sound insulator against low-frequency and wide-band acoustic waves

Science.gov (United States)

Chen, Zhe; Fan, Li; Zhang, Shu-yi; Zhang, Hui; Li, Xiao-juan; Ding, Jin

2015-10-01

To block sound, i.e., the vibration of air, most insulators are based on sealed structures and prevent the flow of the air. In this research, an acoustic metamaterial adopting side structures, loops, and labyrinths, arranged along a main tube, is presented. By combining the accurately designed side structures, an extremely wide forbidden band with a low cut-off frequency of 80 Hz is produced, which demonstrates a powerful low-frequency and wide-band sound insulation ability. Moreover, by virtue of the bypass arrangement, the metamaterial is based on an open structure, and thus air flow is allowed while acoustic waves can be insulated.

Emission characteristics of 6.78-MHz radio-frequency glow discharge plasma in a pulsed mode

Science.gov (United States)

Zhang, Xinyue; Wagatsuma, Kazuaki

2017-07-01

This paper investigated Boltzmann plots for both atomic and ionic emission lines of iron in an argon glow discharge plasma driven by 6.78-MHz radio-frequency (RF) voltage in a pulsed operation, in order to discuss how the excitation/ionization process was affected by the pulsation. For this purpose, a pulse frequency as well as a duty ratio of the pulsed RF voltage was selected as the experimenter parameters. A Grimm-style radiation source was employed at a forward RF power of 70 W and at an argon pressures of 670 Pa. The Boltzmann plot for low-lying excited levels of iron atom was on a linear relationship, which was probably attributed to thermal collisions with ultimate electrons in the negative glow region; in this case, the excitation temperature was obtained in a narrow range of 3300-3400 K, which was hardly affected by the duty ratio as well as the pulse frequency of the pulsed RF glow discharge plasma. This observation suggested that the RF plasma could be supported by a self-stabilized negative glow region, where the kinetic energy distribution of the electrons would be changed to a lesser extent. Additional non-thermal excitation processes, such as a Penning-type collision and a charge-transfer collision, led to deviations (overpopulation) of particular energy levels of iron atom or iron ion from the normal Boltzmann distribution. However, their contributions to the overall excitation/ionization were not altered so greatly, when the pulse frequency or the duty ratio was varied in the pulsed RF glow discharge plasma.

Effects of acute and chronic exposure to both 900 MHz and 2100 MHz electromagnetic radiation on glutamate receptor signaling pathway.

Science.gov (United States)

Gökçek-Saraç, Çiğdem; Er, Hakan; Kencebay Manas, Ceren; Kantar Gok, Deniz; Özen, Şükrü; Derin, Narin

2017-09-01

To demonstrate the molecular effects of acute and chronic exposure to both 900 and 2100 MHz radiofrequency electromagnetic radiation (RF-EMR) on the hippocampal level/activity of some of the enzymes - including PKA, CaMKIIα, CREB, and p44/42 MAPK - from N-methyl-D-aspartate receptor (NMDAR)-related signaling pathways. Rats were divided into the following groups: sham rats, and rats exposed to 900 and 2100 MHz RF-EMR for 2 h/day for acute (1 week) or chronic (10 weeks), respectively. Western blotting and activity measurement assays were used to assess the level/activity of the selected enzymes. The obtained results revealed that the hippocampal level/activity of selected enzymes was significantly higher in the chronic groups as compared to the acute groups at both 900 and 2100 MHz RF-EMR exposure. In addition, hippocampal level/activity of selected enzymes was significantly higher at 2100 MHz RF-EMR than 900 MHz RF-EMR in both acute and chronic groups. The present study provides experimental evidence that both exposure duration (1 week versus 10 weeks) and different carrier frequencies (900 vs. 2100 MHz) had different effects on the protein expression of hippocampus in Wistar rats, which might encourage further research on protection against RF-EMR exposure.

Comparison of 864 and 935 MHz microwave radiation effects on cell culture

International Nuclear Information System (INIS)

Pavicic, I.; Trosic, I.; Sarolic, A.

2005-01-01

The aim of our study was to evaluate and compare the effect of 864 and 935 MHz microwave radiation on proliferation, colony forming and viability of Chinese hamster lung cells, cell line V79. Cell cultures were exposed both to the 864 MHz microwave field in transversal electromagnetic mode cell (TEM-cell) and to the 935 MHz field in Gigahertz transversal electromagnetic mode cell (GTEM-cell) for 1, 2 and 3 hours. Philips PM 5508 generator connected with a signal amplifier generated the frequency of 864 MHz, whereas Hewlett Packard HP8657A signal generator was used to generate the frequency of 935 MHz. The average specific absorption rate (SAR) was 0.08 W/kg for 864 MHz and 0.12 W/kg for 935 MHz. To determine the cell growth, V79 cells were plated in the concentration of 1x10 4 cells per milliliter of nutrient medium. Cells were cultured in a humidified atmosphere at 37 degrees of C in 5% CO 2 . Cell proliferation was determined by cell counts for each hour of exposure during the five post-exposure days. To identify colony-forming ability, cells were cultivated in the concentration of 40 cells/mL of medium and incubated as described above. Colony-forming ability was assessed for each exposure time by colony count on post-exposure day 7. Trypan blue exclusion test was used to determine cell viability. On post-exposure day 3, the growth curve of 864 MHz irradiated cells showed a significant decrease (p less than 0.05) after 2 and 3 hours of exposure in comparison with control cells. Cells exposed to 935 MHz radiation showed a significant decrease (p less than 0.05) after 3 hours of exposure on post-exposure day 3. Both the colony-forming ability and viability of 864 MHz and 935 MHz exposed cells did not significantly differ from matched control cells. In conclusion, both applied RF/MW fields have shown similar effects on cell culture growth, colony forming and cell viability of the V79 cell line.(author)

NICER Discovers mHz Oscillations and Marginally Stable Burning in GS 1826-24

Science.gov (United States)

Strohmayer, Tod E.; Gendreau, Keith C.; Keek, Laurens; Bult, Peter; Mahmoodifar, Simin; Chakrabarty, Deepto; Arzoumanian, Zaven; NICER Science Team

2018-01-01

To date, marginally stable thermonuclear burning, evidenced as mHz X-ray flux oscillations, has been observed in only five accreting neutron star binaries, 4U 1636-536, 4U 1608-52, Aql X-1, 4U 1323-619 and Terzan 5 X-2. Here we report the discovery with NASA's Neutron Star Interior Composition Explorer (NICER) of such oscillations from the well-known X-ray burster GS 1826-24. NICER observed GS 1826-24 on 9 September, 2017 for a total exposure of about 4 ksec. Timing analysis revealed highly significant oscillations at a frequency of 8.2 mHz in two successive pointings. The oscillations have a fractional modulation amplitude of approximately 3% for photon energies less than 6 keV. The observed frequency is consistent with the range observed in the other mHz QPO systems, and indeed is slightly higher than the frequency measured in 4U 1636-536 below which mHz oscillations ceased and unstable burning (X-ray bursts) resumed. We discuss the mass accretion rate dependence of the oscillations as well as the X-ray spectrum as a function of pulsation phase. We place the observations in the context of the current theory of marginally stable burning and briefly discuss the potential for constraining neutron star properties using mHz oscillations.

The importance of different frequency bands in predicting subcutaneous glucose concentration in type 1 diabetic patients.

Science.gov (United States)

Lu, Yinghui; Gribok, Andrei V; Ward, W Kenneth; Reifman, Jaques

2010-08-01

We investigated the relative importance and predictive power of different frequency bands of subcutaneous glucose signals for the short-term (0-50 min) forecasting of glucose concentrations in type 1 diabetic patients with data-driven autoregressive (AR) models. The study data consisted of minute-by-minute glucose signals collected from nine deidentified patients over a five-day period using continuous glucose monitoring devices. AR models were developed using single and pairwise combinations of frequency bands of the glucose signal and compared with a reference model including all bands. The results suggest that: for open-loop applications, there is no need to explicitly represent exogenous inputs, such as meals and insulin intake, in AR models; models based on a single-frequency band, with periods between 60-120 min and 150-500 min, yield good predictive power (error bands produce predictions that are indistinguishable from those of the reference model as long as the 60-120 min period band is included; and AR models can be developed on signals of short length (approximately 300 min), i.e., ignoring long circadian rhythms, without any detriment in prediction accuracy. Together, these findings provide insights into efficient development of more effective and parsimonious data-driven models for short-term prediction of glucose concentrations in diabetic patients.

78 FR 23855 - Improving Public Safety Communications in the 800 MHz Band; New 800 MHz Band Plan for U.S.-Mexico...

Science.gov (United States)

2013-04-23

... rebanding as of the 18th month of the transition period to determine whether additional time is needed based... that ``the rule will not, if promulgated, have a significant economic impact on a substantial number of... nationwide problem of interference created by a fundamentally incompatible mix of technologies in the band...

Simulation of the High-Pass Filter for 56MHz Cavity for RHIC

International Nuclear Information System (INIS)

Wu, Q.; Ben-Zvi, I.

2010-01-01

The 56MHz Superconducting RF (SRF) cavity for RHIC places high demands High Order Mode (HOM) damping, as well as requiring a high field at gap with fundamental mode frequency. The damper of 56MHz cavity is designed to extract all modes to the resistance load outside, including the fundamental mode. Therefore, the circuit must incorporate a high-pass filter to reflect back the fundamental mode into the cavity. In this paper, we show the good frequency response map obtained from our filter's design. We extract a circuit diagram from the microwave elements that simulate well the frequency spectrum of the finalized filter. We also demonstrate that the power dissipation on the filter over its frequency range is small enough for cryogenic cooling.

47 CFR 25.254 - Special requirements for ancillary terrestrial components operating in the 1610-1626.5 MHz/2483.5...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Special requirements for ancillary terrestrial components operating in the 1610-1626.5 MHz/2483.5-2500 MHz bands. 25.254 Section 25.254 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical...

RF MEMS suspended band-stop resonator and filter for frequency and bandwidth continuous fine tuning

International Nuclear Information System (INIS)

Jang, Yun-Ho; Kim, Yong-Kweon; Llamas-Garro, Ignacio; Kim, Jung-Mu

2012-01-01

We firstly propose the concept of a frequency and bandwidth fine-tuning method using an RF MEMS-based suspended tunable band-stop resonator. We experimentally show the feasibility of the continuously tuned resonator, including a second-order filter, which consists of cascaded resonators to achieve center frequency and bandwidth fine tuning. The structure consists of a freestanding half-wavelength (λ/2) resonator connected to a large displacement comb actuator. The lateral movement of the λ/2 resonator over the main transmission line produces different electromagnetic decoupling values from the main transmission line. The decoupled energy leads to continuous center frequency and bandwidth tuning using the band-stop resonator circuit for fine-tuning applications. The freestanding λ/2 resonator plays the role of a variable capacitor as well as a decoupling resonator in the proposed structure. The fabricated tunable filter shows suitability for Ku-band wireless communication system applications with continuous reconfiguration

Characterization of the electromagnetic near-field absorption in layered biological tissue in the frequency range from 30 MHz to 6000 MHz

Energy Technology Data Exchange (ETDEWEB)

Christ, A [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland); Samaras, T [Radiocommunications Laboratory, Aristotle University of Thessaloniki, 541 24 Thessaloniki (Greece); Klingenboeck, A [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland); Kuster, N [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr 43, 8004 Zurich (Switzerland)

2006-10-07

Currently, standards for the compliance testing of wireless devices are being extended to cover a wider frequency band and different usage patterns of mobile phones as well as of novel body-worn and handheld devices. As a consequence, not only the head but also strongly varying tissue distributions of the body are exposed to electromagnetic radiation. Several authors have reported changes in the SAR absorption of body tissue due to the presence of a low permittivity fat layer. This paper identifies two different effects which can lead to increased SAR in layered tissue in comparison to the SAR assessed using homogeneous tissue simulating liquid: (1) for larger distances between the tissue and the antenna, standing wave effects occur depending on the frequency and fat layer thickness. (2) In the very close near-field (distances approximately {lambda}/40), reactive E-field components lead to high local absorption in the skin. The latter effect occurs at lower frequencies and depends on the antenna type. Modification of the parameters of the homogeneous liquids cannot compensate for these effects. However, a conservative exposure estimate can be obtained by applying a multiplication factor between 1 and 3 to the values assessed using current experimental dosimetric techniques.

Generation of three wide frequency bands within a single white-light cavity

Science.gov (United States)

Othman, Anas; Yevick, David; Al-Amri, M.

2018-04-01

We theoretically investigate the double-Λ scheme inside a Fabry-Pérot cavity employing a weak probe beam and two strong driving fields together with an incoherent pumping mechanism. By generating analytical expressions for the susceptibility and applying the white-light cavity conditions, we devise a procedure that reaches the white-light condition at a smaller gas density than the values typically cited in similar previous studies. Further, when the intensities of the two driving fields are equal, a single giant white band is obtained, while for unequal driving fields three white bands can be present in the cavity. Two additional techniques are then advanced for generating three white bands and a method is described for displacing the center frequency of the bands. Finally, some potential applications are suggested.

Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L).

Science.gov (United States)

Cheng, Y; Liu, X J; Wu, D J

2011-03-01

This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters. © 2011 Acoustical Society of America

Analysis of in-band interference in noise-based frequency offset modulation

NARCIS (Netherlands)

Bilal, Ibrahim; Meijerink, Arjan; Bentum, Marinus Jan

2014-01-01

A noise-based frequency offset modulation (N-FOM) system is considered, employing a wideband noise carrier, transmit reference modulation and a self-correlation receiver. The performance of such a system in the presence of in-band interference is studied by modeling the interference as a Gaussian

Monitoring of the state of the paper machine circulation water with a wide-band impedance measurement; Paperikoneen kiertoveden tilan seuranta laajakaistaisella impedanssimittauksella - MPKT 02

Energy Technology Data Exchange (ETDEWEB)

Varpula, T. [VTT Automation, Espoo (Finland). Measurement Technology

1998-12-31

A new measurement method for monitoring the chemical state of the circulation water in the paper machine is proposed and studied. In the method, the electrical properties - conductivity and permittivity - of the water are measured in a wide frequency band: 20 Hz - 10 mhz. Large-molecule organic compounds in the water are expected cause characteristic changes in the dielectric properties of the water. Continuous monitoring of the permittivity in the wide frequency band thus reveals their presence. Various electronic measurement setups for the measurement are constructed and studied by using test samples. If the method turns out to be promising, a prototype device will be made. (orig.)

Monitoring of the state of the paper machine circulation water with a wide-band impedance measurement; Paperikoneen kiertoveden tilan seuranta laajakaistaisella impedanssimittauksella - MPKT 02

Energy Technology Data Exchange (ETDEWEB)

Varpula, T [VTT Automation, Espoo (Finland). Measurement Technology

1999-12-31

A new measurement method for monitoring the chemical state of the circulation water in the paper machine is proposed and studied. In the method, the electrical properties - conductivity and permittivity - of the water are measured in a wide frequency band: 20 Hz - 10 mhz. Large-molecule organic compounds in the water are expected cause characteristic changes in the dielectric properties of the water. Continuous monitoring of the permittivity in the wide frequency band thus reveals their presence. Various electronic measurement setups for the measurement are constructed and studied by using test samples. If the method turns out to be promising, a prototype device will be made. (orig.)

A 6-9 GHz 5-band CMOS synthesizer for MB-OFDM UWB

International Nuclear Information System (INIS)

Chen Pufeng; Li Zhiqiang; Wang Xiaosong; Zhang Haiying; Ye Tianchun

2010-01-01

An ultra-wideband frequency synthesizer is designed to generate carrier frequencies for 5 bands distributed from 6 to 9 GHz with less than 3 ns switching time. It incorporates two phase-locked loops and one single-sideband (SSB) mixer. A 2-to-1 multiplexer with high linearity is proposed. A modified wideband SSB mixer, quadrature VCO, and layout techniques are also employed. The synthesizer is fabricated in a 0.18 μm CMOS process and operates at 1.5-1.8 V while consuming 40 mA current. The measured phase noise is -128 dBc/Hz at 10 MHz offset, and the sideband rejection is -22 dBc at 7.656 GHz.

A 6-9 GHz 5-band CMOS synthesizer for MB-OFDM UWB

Energy Technology Data Exchange (ETDEWEB)

Chen Pufeng; Li Zhiqiang; Wang Xiaosong; Zhang Haiying; Ye Tianchun, E-mail: chenpufeng@ime.ac.c [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

2010-07-15

An ultra-wideband frequency synthesizer is designed to generate carrier frequencies for 5 bands distributed from 6 to 9 GHz with less than 3 ns switching time. It incorporates two phase-locked loops and one single-sideband (SSB) mixer. A 2-to-1 multiplexer with high linearity is proposed. A modified wideband SSB mixer, quadrature VCO, and layout techniques are also employed. The synthesizer is fabricated in a 0.18 {mu}m CMOS process and operates at 1.5-1.8 V while consuming 40 mA current. The measured phase noise is -128 dBc/Hz at 10 MHz offset, and the sideband rejection is -22 dBc at 7.656 GHz.

First Measurements of High Frequency Cross-Spectra from a Pair of Large Michelson Interferometers

Energy Technology Data Exchange (ETDEWEB)

Chou, Aaron S.; Gustafson, Richard; Hogan, Craig; Kamai, Brittany; Kwon, Ohkyung; Lanza, Robert; McCuller, Lee; Meyer, Stephan S.; Richardson, Jonathan; Stoughton, Chris; Tomlin, Raymond; Waldman, Samuel; Weiss, Rainer

2016-09-01

Measurements are reported of high frequency cross-spectra of signals from the Fermilab Holometer, a pair of co-located 39 m, high power Michelson interferometers. The instrument obtains differential position sensitivity to cross-correlated signals far exceeding any previous measurement in a broad frequency band extending to the 3.8 MHz inverse light crossing time of the apparatus. A model of universal exotic spatial shear correlations that matches the Planck scale holographic information bound of space-time position states is excluded to 4.6{\\sigma} significance.

High-efficiency water-loaded microwave antenna in ultra-high-frequency band

Science.gov (United States)

Gong, Zilun; Bartone, Chris; Yang, Fuyi; Yao, Jie

2018-03-01

High-index dielectrics are widely used in microwave antennas to control the radiation characteristics. Liquid water, with a high dielectric index at microwave frequency, is an interesting material to achieving tunable functionalities. Here, we demonstrate a water-loaded microwave antenna system that has high loss-tolerance and wideband tunability enabled by fluidity. Our simulation and experimental results show that the resonance frequency can be effectively tuned by the size of loading water. Furthermore, the antenna systems with water loading can achieve high radiation efficiency (>90%) in the ultra-high-frequency (0.3-3 GHz) band. This work brings about opportunities in realistic tunable microwave antenna designs enabled by liquid.

Frequency Reconfigurable Antenna for Deca-Band 5 G/LTE/WWAN Mobile Terminal Applications

Science.gov (United States)

Yang, Lingsheng; Cheng, Biyu; Jia, Hongting

2018-04-01

In this paper, a frequency reconfigurable antenna for 5 G/LTE/WWAN mobile terminal applications is presented. The proposed antenna consists of a radiation element which is folded on a dielectric cuboid. Four PIN diodes located on the antenna element are used for frequency reconfigration. By controlling the states of four PIN diodes with an 8-bit microcontroller, a broad band which can cover deca-band as LTE700/2300/2500, GSM850/900/1800/1900, UMTS 2100, WLAN2400 and the future 5 G or LTE3600 is obtained with a compacted size of 40×8×5mm3. The antenna gain, efficiency and radiation characteristics are also shown.

A Spectroscopic Comparison of Femtosecond Laser Modified Fused Silica using kHz and MHz Laser Systems.

Energy Technology Data Exchange (ETDEWEB)

Reichman, W J; Krol, D M; Shah, L; Yoshino, F; Arai, A; Eaton, S M; Herman, P R

2005-09-29

Waveguides were written in fused silica using both a femtosecond fiber laser with a 1 MHz pulse repetition rate and a femtosecond amplified Ti:sapphire laser with a 1 kHz repetition rate. Confocal Raman and fluorescence microscopy were used to study structural changes in the waveguides written with both systems. A broad fluorescence band, centered at 650 nm, associated with non-bridging oxygen hole center (NBOHC) defects was observed after waveguide fabrication with the MHz laser. With the kHz laser system these defects were only observed for pulse energies above 1 {mu}J. Far fewer NBOHC defects were formed with the MHz laser than with kHz writing, possibly due to thermal annealing driven by heat accumulation effects at 1 MHz. When the kHz laser was used with pulse energies below 1 {mu}J, the predominant fluorescence was centered at 550 nm, a band assigned to the presence of silicon clusters (E{prime}{sub {delta}}). We also observed an increase in the intensity of the 605 cm{sup -1} Raman peak relative to the total Raman intensity, corresponding to an increase in the concentration of 3-membered rings in the lines fabricated with both laser systems.

Electron heating mode transition induced by mixing radio frequency and ultrahigh frequency dual frequency powers in capacitive discharges

International Nuclear Information System (INIS)

Sahu, B. B.; Han, Jeon G.

2016-01-01

Electron heating mode transitions induced by mixing the low- and high-frequency power in dual-frequency nitrogen discharges at 400 mTorr pressure are presented. As the low-frequency (13.56 MHz) power decreases and high-frequency (320 MHz) power increases for the fixed power of 200 W, there is a transition of electron energy distribution function (EEDF) from Druyvesteyn to bi-Maxwellian type characterized by a distinguished warm electron population. It is shown that this EEDF evolution is attributed to the transition from collisional to collisionless stochastic heating of the low-energy electrons.

ISM (Industrial Scientific and Medical standard) band flex fuel sensor using electrical metamaterial device

Science.gov (United States)

Rawat, Vaishali; Nadkarni, Vihang; Kale, S. N.

2017-01-01

A stand-alone device working on the electrical metamaterial concept, operating at 2.47 GHz (ISM band), using merely 10 μL sample is proposed to detect petrol/ethanol ratio in given hybrid fuel. Systematic shifts in the transmission frequency as well as magnitude are observed, up to a maximum of 160 MHz and 12 dBm with the hybrid fuels. The sensing was fast with an instantaneous recovery, promising an accurate and sensitive device of detection of flex fuel.

Results of using frequency banded SAFT for examining three types of defects

Science.gov (United States)

Clayton, Dwight; Barker, Alan; Santos-Villalobos, Hector

2017-02-01

A multitude of concrete-based structures are typically part of a light water reactor (LWR) plant to provide the foundation, support, shielding, and containment functions. Concrete has been used in the construction of nuclear power plants (NPPs) because of three primary properties; its low cost, structural strength, and ability to shield radiation. Examples of concrete structures important to the safety of LWR plants include the containment building, spent fuel pool, and cooling towers. This use has made concrete's long-term performance crucial for the safe operation of commercial NPPs. Extending reactor life to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. Additionally, new mechanisms of materials degradation are also possible. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular Nondestructive Evaluation (NDE) technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Because conditions in the laboratory are controlled, the number of unknown variables can be decreased, making it possible to focus on specific aspects, investigate them in detail, and gain further information on the capabilities and limitations of each method. To minimize artifacts caused by boundary effects, the dimensions of the specimens should not be too compact. In this paper, we apply the frequency banded Synthetic Aperture Focusing Technique (SAFT) technique to a 2.134 m × 2.134 m × 1.016 m concrete test specimen with twenty deliberately embedded defects. These twenty embedded defects simulate voids (honeycombs), delamination, and embedded organic construction debris. Using the time-frequency technique of wavelet packet decomposition and reconstruction, the spectral content of the signal can be divided into two resulting child nodes. The resulting two nodes can then

Analysis of Broad-band Frequency Selective Shielding Glass by FDTD method

OpenAIRE

笠嶋, 善憲; Kasashima, Yoshinori

2010-01-01

A frequency Selective shielding (FSS) glass is a print of many same size antennas on a sheet of glass, and it has high shielding properties for one specific frequency. In the past, the author analyzed theoretically the characteristics of the FSS, as a large scale array antenna. The FSS has narrow-band shielding characteristics. This time, the author analyzed accurately the characteristics of a FSS glass being a print of many same size dipole antennas on a sheet of glass by FDTD method. As the...

Analog Fiber Optic Link with DC-100 MHz Bandwidth

National Research Council Canada - National Science Library

Sullivan, C. A; Girardi, P. G; Lohrmann, Dieter R

2008-01-01

An analog fiber optic link covering the frequency range from DC to 100 MHz was designed, constructed, and tested, in order to connect a 10 kA pulse current probe to oscilloscopes for oscillographing...

Early 500 MHz prototype LEP RF Cavity with superposed storage cavity

CERN Multimedia

CERN PhotoLab

1981-01-01

The principle of transferring the RF power back and forth between the accelerating cavity and a side-coupled storage cavity was demonstrated with this 500 MHz prototype. In LEP, the accelerating frequency was 352.2 MHz, and accelerating and storage cavities were consequently larger. See also 8002294, 8006061, 8407619X, and Annual Reports 1980, p.115; 1981, p.95; 1985, vol.I, p.13.

Dual Band a-Si:H Solar-Slot Antenna for 2.4/5.2GHz WLAN Applications

Directory of Open Access Journals (Sweden)

S. V. Shynu

2009-12-01

Full Text Available A simple and compact design of solar-slot antenna for dual band 2.4/5.2GHz wireless local area networks (WLAN applications is proposed. The design employs amorphous silicon (a-Si:H solar cells in polyimide substrate with an embedded twin strip slot structure to generate dual resonant frequencies. A T-shaped microstripline feed is used to excite the twin slot in the a-Si:H solar cell. The measured impedance bandwidths for the proposed solar antenna are 25.9% (642 MHz centered at 2.482 GHz and 8.2% (420 MHz centered at 5.098 GHz. The measured gain at 2.4 and 5.2 GHz are 3.1 dBi and 2.1 dBi respectively.

A 0.13 μm CMOS ΔΣ fractional-N frequency synthesizer for WLAN transceivers

International Nuclear Information System (INIS)

Chu Xiaojie; Jia Hailong; Lin Min; Shi Yin; Foster, Dai Fa

2011-01-01

A fractional-N frequency synthesizer fabricated in a 0.13 μm CMOS technology is presented for the application of IEEE 802.11 b/g wireless local area network (WLAN) transceivers. A monolithic LC voltage controlled oscillator (VCO) is implemented with an on-chip symmetric inductor. The fractional-N frequency divider consists of a pulse swallow frequency divider and a 3rd-order multistage noise shaping (MASH) ΔΣ modulator with noise-shaped dithering techniques. Measurement results show that in all channels, phase noise of the synthesizer achieves −93 dBc/Hz and −118 dBc/Hz in band and out of band respectively with a phase-frequency detector (PFD) frequency of 20 MHz and a loop bandwidth of 100 kHz. The integrated RMS phase error is no more than 0.8°. The proposed synthesizer consumes 8.4 mW from a 1.2 V supply and occupies an area of 0.86 mm 2 . (semiconductor integrated circuits)

A 0.13 μm CMOS ΔΣ fractional-N frequency synthesizer for WLAN transceivers

Science.gov (United States)

Xiaojie, Chu; Hailong, Jia; Min, Lin; Yin, Shi; Foster, Dai Fa

2011-10-01

A fractional-N frequency synthesizer fabricated in a 0.13 μm CMOS technology is presented for the application of IEEE 802.11 b/g wireless local area network (WLAN) transceivers. A monolithic LC voltage controlled oscillator (VCO) is implemented with an on-chip symmetric inductor. The fractional-N frequency divider consists of a pulse swallow frequency divider and a 3rd-order multistage noise shaping (MASH) ΔΣ modulator with noise-shaped dithering techniques. Measurement results show that in all channels, phase noise of the synthesizer achieves -93 dBc/Hz and -118 dBc/Hz in band and out of band respectively with a phase-frequency detector (PFD) frequency of 20 MHz and a loop bandwidth of 100 kHz. The integrated RMS phase error is no more than 0.8°. The proposed synthesizer consumes 8.4 mW from a 1.2 V supply and occupies an area of 0.86 mm2.

Development of 400- to 450-MHz RFQ resonator-cavity mechanical designs

International Nuclear Information System (INIS)

Hansborough, L.D.

1982-01-01

In the development of the radio-frequency quadrupole (RFQ) linac, the resonator cavity's mechanical design may be a challenge similar in magnitude to that of the development of the accelerator structure itself. Experience with the all-copper 425-MHz RFQ proof-of-principle linac has demonstrated that the resonator cavity must be structurally stiff and easily tunable. This experience has led to development of copper-plated steel structures having vanes that may be moved within a cylinder for tuning. Design of a flexible vane-to-cylinder radio-frequency (rf) joint, the vane, and the cylinder has many constraints dictated by the small-diameter cavities in the 400-MHz-frequency region. Two types of flexible, mechanical vane-to-cylinder rf joints are being developed at Los Alamos: the C-seal and the rf clamp-joint

VizieR Online Data Catalog: The VLA Low-frequency Sky Survey at 74MHz (Perley+ 2006)

Science.gov (United States)

Perley, R. A.; Condon, J. J.; Cotton, W. D.; Cohen, A. S.; Lane, W. M.; Kassim, N. E.; Lazio, T. J. W.; Erickson, W. C.

2006-08-01

The VLA Low-Frequency Sky Survey (VLSS) is a 74MHz (4m) continuum survey covering the entire sky north of -30{deg} declination. Using the VLA in B- and BnA-configurations, we will map the entire survey region at a resolution of 80" and with an average rms noise of 0.1 Jy/beam. For a detailed description of the survey and its scientific motivations, please see the original proposal to the NRAO skeptical review committee. The VLSS is being made as a service to the astronomical community, and the principal data products are being released to the public as soon as they are produced and verified. Details and access to the images can be found at http://lwa.nrl.navy.mil/VLSS/ (1 data file).

VizieR Online Data Catalog: The VLA Low-frequency Sky Survey at 74MHz (Cohen+ 2007)

Science.gov (United States)

Cohen, A. S.; Lane, W. M.; Cotton, W. D.; Kassim, N. E.; Lazio, T. J. W.; Perley, R. A.; Condon, J. J.; Erickson, W. C.

2006-08-01

The VLA Low-Frequency Sky Survey (VLSS) is a 74MHz (4m) continuum survey covering the entire sky north of -30{deg} declination. Using the VLA in B- and BnA-configurations, we will map the entire survey region at a resolution of 80" and with an average rms noise of 0.1 Jy/beam. For a detailed description of the survey and its scientific motivations, please see the original proposal to the NRAO skeptical review committee. The VLSS is being made as a service to the astronomical community, and the principal data products are being released to the public as soon as they are produced and verified. Details and access to the images can be found at http://lwa.nrl.navy.mil/VLSS/ (1 data file).

Analysis of high resolution land clutter using an X-band radar

CSIR Research Space (South Africa)

Melebari, A

2015-10-01

Full Text Available . Measurements were performed with an X-band radar system with two instantaneous bandwidths of 40 MHz and 400 MHz. The clutter data was analyzed by fitting the amplitude Probability Distribution Function (PDF) to different distributions using the Method...

Electrostatic noise bands associated with the electron gyrofrequency and plasma frequency in the outer magnetosphere

International Nuclear Information System (INIS)

Shaw, R.R.

1975-01-01

Naturally occurring noise bands near the electron plasma frequency are frequently detected by the University of Iowa plasma wave experiment on the IMP 6 satellite in the region from just inside the plasmapause to radial distances of about 10 earth radii in the outer magnetosphere. The electric field strength of these noise bands is usually small with electric field spectral densities near 10 -15 volts 2 meter -2 Hz -1 . A wave magnetic field has been detected only in a few unusually intense cases, and in these cases the magnetic field energy density is several orders of magnitude smaller than the electric field energy density. The bands are observed at all magnetic latitudes covered by the IMP 6 orbit (parallelγ/sub m/parallel less than or equal to 45 0 ) and appear to be a permanent feature of the outer magnetosphere. They are found at all local times and occur least frequently in the quadrant from 18 to 24 hours. The bands appear to consist of two distinct spectral types, diffuse and narrow. In both types the center frequency of the noise band is bounded by consecutive harmonics of the electron gyrofrequency, and the bands occur most often between harmonics that are near the local electron plasma frequency. These bands appear to merge continuously into two types of plasma wave emissions that are found in dissimilar regions of the magnetosphere (upper hybrid resonance noise, also called Region 3 noise, inside the plasmasphere and (n + 1/2)f/sub g/ harmonics in the outer magnetosphere). It is suggested that this smooth merging is caused by changes in the plasma wave dispersion relation that occur as the spacecraft moves from the cold plasma within the plasmasphere into the warm non-Maxwellian plasma found in the outer magnetosphere

Solid state Ka-band pulse oscillator with frequency electronic switching

Directory of Open Access Journals (Sweden)

Dvornichenko V. P.

2015-08-01

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

Frequency scanning microstrip antennas

DEFF Research Database (Denmark)

Danielsen, Magnus; Jørgensen, Rolf

1979-01-01

The principles of using radiating microstrip resonators as elements in a frequency scanning antenna array are described. The resonators are cascade-coupled. This gives a scan of the main lobe due to the phase-shift in the resonator in addition to that created by the transmission line phase......-shift. Experimental results inX-band, in good agreement with the theory, show that it is possible to scan the main lobe an angle ofpm30degby a variation of the frequencypm300MHz, and where the 3 dB beamwidth is less than10deg. The directivity was 14.7 dB, while the gain was 8.1 dB. The efficiency might be improved...

Operating experience of upgraded radio frequency source at 76 MHz coupled to heavy ion RFQ

International Nuclear Information System (INIS)

Pande, Manjiri; Shiju, A.; Patel, N.R.; Shrotriya, S.D.; Bhagwat, P.V.

2015-01-01

A heavy ion radio frequency quadrupole (RFQ) accelerator has been developed at BARC (BARC). A RF source which was designed and developed at 76 MHz earlier, has been upgraded and coupled to heavy ion RFQ successfully. The DC bias supplies of this source have been replaced with new supplies having high efficiency and well filteration against RF interference (RFI). The driver of main power amplifier has been replaced with indigenously designed and developed unit. The earlier introduced microcontroller based interlock experienced RF noise issues. So, this circuit has been modified with the new circuit. With these modifications, the performance of the RF source was improved. Additionally, a separate low power RF source of around 100 + Watt was designed, developed and integrated with RFQ for its RF conditioning. This paper describes the details of up gradation of technologies implemented and coupling experience of this RF source with heavy ion RFQ. (author)

Balanced G-band Gm-boosted frequency doublers in transferred substrate InP HBT technology

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Thualfiqar, Al-Sawaf; Weimann, Nils

2016-01-01

In this paper, balanced G-band Gm-boosted frequency doublers in transferred substrate (TS) InP HBT technology are reported for the first time. The Gm-boosted frequency doublers consist of a phase compensated Marchand balun, Gm-boosted doubler stage, and an optional cascode gain stage at the outpu...

A high dynamic range programmable CMOS front-end filter with a tuning range from 1850 to 2400 MHz

DEFF Research Database (Denmark)

Christensen, Kåre Tais; Lee, Thomas H.; Bruun, Erik

2005-01-01

This paper presents a highly programmable front-end filter and amplifier intended to replace SAW filters and low noise amplifiers (LNA) in multi-mode direct conversion radio receivers. The filter has a 42 MHz bandwidth, is tunable from 1850 to 2400 MHz, achieves a 5.8 dB NF, -25 dBm in-band 1-d...

Suitable RF spectrum in ISM band for 2-way advanced metering network in India

Science.gov (United States)

Mishra, A.; Khan, M. A.; Gaur, M. S.

2013-01-01

The ISM (Industrial Scientific and Medical) bands in the radio frequency space in India offer two alternative spectra to implement wireless network for advanced metering infrastructure (AMI). These bands lie in the range of 2.4GHz and sub-GHz frequencies 865 to 867 MHz This paper aims to examine the suitability of both options by designing and executing experiments in laboratory as well as carrying out field trials on electricity meters to validate the selected option. A parameter, communication effectiveness index (CEI2) is defined to measure the effectiveness of 2 way data communication (packet exchange) between two points under different scenarios of buildings and free space. Both 2.4 GHz and Sub-GHz designs were implemented to compare the results. The experiments were conducted across 3 floors of a building. Validation of the selected option was carried out by conducting a field trial by integrating the selected radio frequency (RF) modem into the single phase electricity meters and installing these meters across three floors of the building. The methodology, implementation details, observations and resulting analytical conclusion are described in the paper.

Low-frequency and multiple-bands sound insulation using hollow boxes with membrane-type faces

Science.gov (United States)

Yu, Wei-wei; Fan, Li; Ma, Ren-hao; Zhang, Hui; Zhang, Shu-yi

2018-04-01

Hollow boxes with their faces made up of elastic membranes are used to block acoustic waves. It is demonstrated that placing a cuboid membrane-type box inside a pipe can effectively insulate acoustic waves even if the box is smaller than the cross-section of the pipe. The sound insulation is achieved within multiple frequency-bands below 500 Hz based on different mechanisms, which originate from the coaction of the cavity, membrane-type faces, and the intervals between the box and pipe walls. Furthermore, by adjusting the structural parameters and establishing an array of boxes, we can achieve better sound insulation at more frequency-bands.

Developments and directions in 200 MHz very high power RF at LAMPF

International Nuclear Information System (INIS)

Cliff, R.; Bush, E.D.; DeHaven, R.A.; Harris, H.W.; Parsons, M.

1991-01-01

The Los Alamos Meson Physics Facility (LAMPF), is a linear particle accelerator a half-mile long. It produces an 800 million electron- volt hydrogen-ion beam at an average current of more than one milliamp. The first RF section of the accelerator consists of four Alvarez drift-tube structures. Each of these structures is excited by an amplifier module at a frequency of 201.25 MHz. These amplifiers operate at a duty of 13 percent or more and at peak pulsed power levels of about 2.5 million watts. The second RF accelerator section consists of forty-four side-coupled-cavity structures. Each of these is excited by an amplifier module at a frequency of 805 MHz. These amplifiers operate at a duty of up to 12 percent and at peak pulsed power levels of about 1.2 million watts. The relatively high average beam current in the accelerator places a heavy demand upon components in the RF systems. The 201-MHz modules have always required a large share of maintenance efforts. In recent years, the four 201.25 MHz modules have been responsible for more than twice as much accelerator down-time as have the forty-four 805 MHz modules. This paper reviews recent, ongoing, and planned improvements in the 201-MHz systems. The Burle Industries 7835 super power triode is used in the final power amplifiers of each of the 201-MHz modules. This tube has been modified for operation at LAMPF by the addition of Penning ion vacuum''pumps.'' This has enabled more effective tube conditioning and restarting. A calorimetry system of high accuracy is in development to monitor tube plate-power dissipation

[Effect of Low-Intensity 900 MHz Frequency Electromagnetic Radiation on Rat Brain Enzyme Activities Linked to Energy Metabolism].

Science.gov (United States)

Petrosyan, M S; Nersesova, L S; Gazaryants, M G; Meliksetyan, G O; Malakyan, M G; Bajinyan, S A; Akopian, J I

2015-01-01

The research deals with the effect of low-intensity 900 MHz frequency electromagnetic radiation (EMR), power density 25 μW/cm2, on the following rat brain and blood serum enzyme activities: creatine kinase (CK), playing a central role in the process of storing and distributing the cell energy, as well as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) that play a key role in providing the conjunction of carbohydrate and amino acid metabolism. The comparative analysis of the changes in the enzyme activity studied at different times following the two-hour single, as well as fractional, radiation equivalent of the total time showed that the most radiosensitive enzyme is the brain creatine kinase, which may then be recommended as a marker of the radio frequency radiation impact. According to the analysis of the changing dynamics of the CK, ALT and AST activity level, with time these changes acquire the adaptive character and are directed to compensate the damaged cell energy metabolism.

Fatigue level estimation of monetary bills based on frequency band acoustic signals with feature selection by supervised SOM

Science.gov (United States)

Teranishi, Masaru; Omatu, Sigeru; Kosaka, Toshihisa

Fatigued monetary bills adversely affect the daily operation of automated teller machines (ATMs). In order to make the classification of fatigued bills more efficient, the development of an automatic fatigued monetary bill classification method is desirable. We propose a new method by which to estimate the fatigue level of monetary bills from the feature-selected frequency band acoustic energy pattern of banking machines. By using a supervised self-organizing map (SOM), we effectively estimate the fatigue level using only the feature-selected frequency band acoustic energy pattern. Furthermore, the feature-selected frequency band acoustic energy pattern improves the estimation accuracy of the fatigue level of monetary bills by adding frequency domain information to the acoustic energy pattern. The experimental results with real monetary bill samples reveal the effectiveness of the proposed method.

Study of a dual frequency atmospheric pressure corona plasma

International Nuclear Information System (INIS)

Kim, Dan Bee; Moon, S. Y.; Jung, H.; Gweon, B.; Choe, Wonho

2010-01-01

Radio frequency mixing of 2 and 13.56 MHz was investigated by performing experimental measurements on the atmospheric pressure corona plasma. As a result of the dual frequency, length, current density, and electron excitation temperature of the plasma were increased, while the gas temperature was maintained at roughly the same level when compared to the respective single frequency plasmas. Moreover, observation of time-resolved images revealed that the dual frequency plasma has a discharge mode of 2 MHz positive streamer, 2 MHz negative glow, and 13.56 MHz continuous glow.

Effects of weak nonlinearity on dispersion relations and frequency band-gaps of periodic structures

DEFF Research Database (Denmark)

Sorokin, Vladislav; Thomsen, Jon Juel

2015-01-01

of these for nonlinear problems is impossible or cumbersome, since Floquet theory is applicable for linear systems only. Thus the nonlinear effects for periodic structures are not yet fully uncovered, while at the same time applica-tions may demand effects of nonlinearity on structural response to be accounted for....... The present work deals with analytically predicting dynamic responses for nonlinear continuous elastic periodic structures. Specifically, the effects of weak nonlinearity on the dispersion re-lation and frequency band-gaps of a periodic Bernoulli-Euler beam performing bending os-cillations are analyzed......The analysis of the behaviour of linear periodic structures can be traced back over 300 years, to Sir Isaac Newton, and still attracts much attention. An essential feature of periodic struc-tures is the presence of frequency band-gaps, i.e. frequency ranges in which waves cannot propagate...

LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY

Energy Technology Data Exchange (ETDEWEB)

McKinley, B.; Briggs, F. [Research School of Astronomy and Astrophysics, Australian National University, Canberra (Australia); Kaplan, D. L. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI (United States); Greenhill, L. J.; Bernardi, G.; De Oliveira-Costa, A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Bowman, J. D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Tingay, S. J.; Gaensler, B. M. [ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), School of Physics, The University of Sydney, Sydney, NSW (Australia); Oberoi, D. [National Centre for Radio Astrophysics, Tata Institute for Fundamental Research, Pune (India); Johnston-Hollitt, M. [School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington (New Zealand); Arcus, W.; Emrich, D. [International Centre for Radio Astronomy Research, Curtin University, Perth (Australia); Barnes, D. [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne (Australia); Bunton, J. D. [CSIRO Astronomy and Space Science, Canberra (Australia); Cappallo, R. J.; Corey, B. E. [MIT Haystack Observatory, Westford, MA (United States); Deshpande, A. [Raman Research Institute, Bangalore (India); DeSouza, L. [Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney (Australia); Goeke, R. [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA (United States); and others

2013-01-01

A new generation of low-frequency radio telescopes is seeking to observe the redshifted 21 cm signal from the epoch of reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of wide-field low-frequency radio interferometry. Precise calibration will be required to separate the expected small EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300 MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognized frequency modulated (FM) radio band. The observations have implications for future low-frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at meter wavelengths to an observer beyond our own solar system.

An Empirical Outdoor-to-Indoor Path Loss Model from below 6 GHz to cm-Wave Frequency Bands

DEFF Research Database (Denmark)

Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Kovács, István Z.

2017-01-01

This letter presents an empirical multi-frequency outdoor-to-indoor path loss model. The model is based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5 and 5.2 GHz), up to cm-wave fre......This letter presents an empirical multi-frequency outdoor-to-indoor path loss model. The model is based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5 and 5.2 GHz), up to cm...

Dual-etalon cavity ring-down frequency-comb spectroscopy with broad band light source

Science.gov (United States)

Chandler, David W; Strecker, Kevin E

2014-04-01

In an embodiment, a dual-etalon cavity-ring-down frequency-comb spectrometer system is described. A broad band light source is split into two beams. One beam travels through a first etalon and a sample under test, while the other beam travels through a second etalon, and the two beams are recombined onto a single detector. If the free spectral ranges ("FSR") of the two etalons are not identical, the interference pattern at the detector will consist of a series of beat frequencies. By monitoring these beat frequencies, optical frequencies where light is absorbed may be determined.

Feasibility Studies on the Use of Higher Frequency Bands and Beamforming Selection Scheme for High Speed Train Communication

Directory of Open Access Journals (Sweden)

Ayotunde O. Laiyemo

2017-01-01

Full Text Available With increasing popularity of high speed trains and traffic forecast for future cellular networks, the need to provide improved data rates using higher frequency bands (HFBs for train passengers is becoming crucial. In this paper, we modify the OFDM frame structure for HST, taking into account the increasing sensitivity to speed at HFBs. A lower bound on the SNR/SINR for a given rate for reliable communication was derived considering the physical layer parameters from the OFDM frame. We also analyze different pathloss models in the context of examining the required gain needed to achieve the same performance as with microwave bands. Finally, we present a time-based analogue beamforming selection approach for HST. We observed that, irrespective of the pathloss models used, the required gains are within the same range. For the same SNR/SINR at different frequency bands, the achievable data rate varies with respect to the frequency bands. Our results show the potential of the use of HFBs. However, due to the increased sensitivity of some channel parameters, a maximum frequency band of 38 GHz is suggested. Evaluation of our proposed beamforming scheme indicates a close performance to the optimal SVD scheme with a marginal rate gap of less than 2 b/s/Hz.

Heat transfer enhancement using 2MHz ultrasound.

Science.gov (United States)

Bulliard-Sauret, Odin; Ferrouillat, Sebastien; Vignal, Laure; Memponteil, Alain; Gondrexon, Nicolas

2017-11-01

The present work focuses on possible heat transfer enhancement from a heating plate towards tap water in forced convection by means of 2MHz ultrasound. The thermal approach allows to observe the increase of local convective heat transfer coefficients in the presence of ultrasound and to deduce a correlation between ultrasound power and Nusselt number. Heat transfer coefficient under ultrasound remains constant while heat transfer coefficient under silent conditions increases with Reynolds number from 900 up to 5000. Therefore, heat transfer enhancement factor ranges from 25% up to 90% for the same energy conditions (supplied ultrasonic power=110W and supplied thermal power=450W). In the same time cavitational activity due to 2MHz ultrasound emission was characterized from mechanical and chemical viewpoints without significant results. At least, Particle Image Velocimetry (PIV) measurements have been performed in order to investigate hydrodynamic modifications due to the presence of 2MHz ultrasound. It was therefore possible to propose a better understanding of heat transfer enhancement mechanism with high frequency ultrasound. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals

Science.gov (United States)

Bakir, A.; Rocher, C.; Maréchal, B.; Bigler, E.; Boudot, R.; Kersalé, Y.; Millo, J.

2018-05-01

We report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10-14 at 1 s integration time and in the low 10-16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz-1 GHz range.

A chip-scale, telecommunications-band frequency conversion interface for quantum emitters.

Science.gov (United States)

Agha, Imad; Ates, Serkan; Davanço, Marcelo; Srinivasan, Kartik

2013-09-09

We describe a chip-scale, telecommunications-band frequency conversion interface designed for low-noise operation at wavelengths desirable for common single photon emitters. Four-wave-mixing Bragg scattering in silicon nitride waveguides is used to demonstrate frequency upconversion and downconversion between the 980 nm and 1550 nm wavelength regions, with signal-to-background levels > 10 and conversion efficiency of ≈ -60 dB at low continuous wave input pump powers ( 25 % in existing geometries. Finally, we present waveguide designs that can be used to connect shorter wavelength (637 nm to 852 nm) quantum emitters with 1550 nm.

The 40 MHz trigger-less DAQ for the LHCb Upgrade

Energy Technology Data Exchange (ETDEWEB)

Campora Perez, D.H. [INFN CNAF, Bologna (Italy); Falabella, A., E-mail: antonio.falabella@cnaf.infn.it [CERN, Geneva (Switzerland); Galli, D. [INFN Sezione di Bologna, Bologna (Italy); Università Bologna, Bologna (Italy); Giacomini, F. [CERN, Geneva (Switzerland); Gligorov, V. [INFN CNAF, Bologna (Italy); Manzali, M. [Università Bologna, Bologna (Italy); Università Ferrara, Ferrara (Italy); Marconi, U. [INFN Sezione di Bologna, Bologna (Italy); Neufeld, N.; Otto, A. [INFN CNAF, Bologna (Italy); Pisani, F. [INFN CNAF, Bologna (Italy); Università la Sapienza, Roma (Italy); Vagnoni, V.M. [INFN Sezione di Bologna, Bologna (Italy)

2016-07-11

The LHCb experiment will undergo a major upgrade during the second long shutdown (2018–2019), aiming to let LHCb collect an order of magnitude more data with respect to Run 1 and Run 2. The maximum readout rate of 1 MHz is the main limitation of the present LHCb trigger. The upgraded detector, apart from major detector upgrades, foresees a full read-out, running at the LHC bunch crossing frequency of 40 MHz, using an entirely software based trigger. A new high-throughput PCIe Generation 3 based read-out board, named PCIe40, has been designed for this purpose. The read-out board will allow an efficient and cost-effective implementation of the DAQ system by means of high-speed PC networks. The network-based DAQ system reads data fragments, performs the event building, and transports events to the High-Level Trigger at an estimated aggregate rate of about 32 Tbit/s. Different architecture for the DAQ can be implemented, such as push, pull and traffic shaping with barrel-shifter. Possible technology candidates for the foreseen event-builder under study are InfiniBand and Gigabit Ethernet. In order to define the best implementation of the event-builder we are performing tests of the event-builder on different platforms with different technologies. For testing we are using an event-builder evaluator, which consists of a flexible software implementation, to be used on small size test beds as well as on HPC scale facilities. The architecture of DAQ system and up to date performance results will be presented.

Resting-state functional under-connectivity within and between large-scale cortical networks across three low-frequency bands in adolescents with autism.

Science.gov (United States)

Duan, Xujun; Chen, Heng; He, Changchun; Long, Zhiliang; Guo, Xiaonan; Zhou, Yuanyue; Uddin, Lucina Q; Chen, Huafu

2017-10-03

Although evidence is accumulating that autism spectrum disorder (ASD) is associated with disruption of functional connections between and within brain networks, it remains largely unknown whether these abnormalities are related to specific frequency bands. To address this question, network contingency analysis was performed on brain functional connectomes obtained from 213 adolescent participants across nine sites in the Autism Brain Imaging Data Exchange (ABIDE) multisite sample, to determine the disrupted connections between and within seven major cortical networks in adolescents with ASD at Slow-5, Slow-4 and Slow-3 frequency bands and further assess whether the aberrant intra- and inter-network connectivity varied as a function of ASD symptoms. Overall under-connectivity within and between large-scale intrinsic networks in ASD was revealed across the three frequency bands. Specifically, decreased connectivity strength within the default mode network (DMN), between DMN and visual network (VN), ventral attention network (VAN), and between dorsal attention network (DAN) and VAN was observed in the lower frequency band (slow-5, slow-4), while decreased connectivity between limbic network (LN) and frontal-parietal network (FPN) was observed in the higher frequency band (slow-3). Furthermore, weaker connectivity within and between specific networks correlated with poorer communication and social interaction skills in the slow-5 band, uniquely. These results demonstrate intrinsic under-connectivity within and between multiple brain networks within predefined frequency bands in ASD, suggesting that frequency-related properties underlie abnormal brain network organization in the disorder. Copyright © 2017 Elsevier Inc. All rights reserved.

Dielectric spectroscopy in aqueous solutions of paracetamol over the frequency range of 20 Hz to 2 MHz at 293.15 K temperature

Science.gov (United States)

Pandit, T. R.; Rana, V. A.

2018-05-01

Frequency domain dielectric relaxation spectroscopy plays an important role in the study of pharmaceutical drug molecules. The complex relative dielectric permittivity ɛ*(ω) = ɛ' - j ɛ" of aqueous solutions of paracetamol in the frequency range of 20 Hz to 2 MHz at a temperature range of 293.15 K are measured with the help of Agilent precision LCR meter E4980A along with four terminal liquid test fixture Agilent 16452A. Data of complex relative permittivity are used to calculate loss tangent for all concentrations of paracetamol in distilled water. Electrode polarization relaxation time has been calculated for all solutions. Effect of variation of concentrations of paracetamol in distilled water on these dielectric parameters is discussed.

Balanced homodyne detection of optical quantum states at audio-band frequencies and below

International Nuclear Information System (INIS)

Stefszky, M S; Mow-Lowry, C M; Chua, S S Y; Shaddock, D A; Buchler, B C; Lam, P K; McClelland, D E; Vahlbruch, H; Khalaidovski, A; Schnabel, R

2012-01-01

The advent of stable, highly squeezed states of light has generated great interest in the gravitational wave community as a means for improving the quantum-noise-limited performance of advanced interferometric detectors. To confidently measure these squeezed states, it is first necessary to measure the shot-noise across the frequency band of interest. Technical noise, such as non-stationary events, beam pointing, and parasitic interference, can corrupt shot-noise measurements at low Fourier frequencies, below tens of kilo-hertz. In this paper we present a qualitative investigation into all of the relevant noise sources and the methods by which they can be identified and mitigated in order to achieve quantum noise limited balanced homodyne detection. Using these techniques, flat shot-noise down to Fourier frequencies below 0.5 Hz is produced. This enables the direct observation of large magnitudes of squeezing across the entire audio-band, of particular interest for ground-based interferometric gravitational wave detectors. 11.6 dB of shot-noise suppression is directly observed, with more than 10 dB down to 10 Hz. (paper)

Narrow-band 1, 2, 3, 4, 8, 16 and 24 cycles/360o angular frequency filters

Directory of Open Access Journals (Sweden)

Simas M.L.B.

2002-01-01

Full Text Available We measured human frequency response functions for seven angular frequency filters whose test frequencies were centered at 1, 2, 3, 4, 8, 16 or 24 cycles/360º using a supra-threshold summation method. The seven functions of 17 experimental conditions each were measured nine times for five observers. For the arbitrarily selected filter phases, the maximum summation effect occurred at test frequency for filters at 1, 2, 3, 4 and 8 cycles/360º. For both 16 and 24 cycles/360º test frequencies, maximum summation occurred at the lower harmonics. These results allow us to conclude that there are narrow-band angular frequency filters operating somehow in the human visual system either through summation or inhibition of specific frequency ranges. Furthermore, as a general result, it appears that addition of higher angular frequencies to lower ones disturbs low angular frequency perception (i.e., 1, 2, 3 and 4 cycles/360º, whereas addition of lower harmonics to higher ones seems to improve detection of high angular frequency harmonics (i.e., 8, 16 and 24 cycles/360º. Finally, we discuss the possible involvement of coupled radial and angular frequency filters in face perception using an example where narrow-band low angular frequency filters could have a major role.

78 FR 8229 - Service Rules for Advanced Wireless Services in the 2000-2020 MHz and 2180-2200 MHz Bands, etc.

Science.gov (United States)

2013-02-05

... band in this proceeding; such determinations are outside its scope. However, in our role as spectrum... the AWS-4 and 2 GHz MSS uplink bands and harmful overload interference, if any occurs, from operators...

Comparative study of laminar and turbulent flow model with different operating parameters for radio frequency-inductively coupled plasma torch working at 3  MHz frequency at atmospheric pressure

International Nuclear Information System (INIS)

Punjabi, Sangeeta B.; Sahasrabudhe, S. N.; Das, A. K.; Joshi, N. K.; Mangalvedekar, H. A.; Kothari, D. C.

2014-01-01

This paper provides 2D comparative study of results obtained using laminar and turbulent flow model for RF (radio frequency) Inductively Coupled Plasma (ICP) torch. The study was done for the RF-ICP torch operating at 50 kW DC power and 3 MHz frequency located at BARC. The numerical modeling for this RF-ICP torch is done using ANSYS software with the developed User Defined Function. A comparative study is done between laminar and turbulent flow model to investigate how temperature and flow fields change when using different operating conditions such as (a) swirl and no swirl velocity for sheath gas flow rate, (b) variation in sheath gas flow rate, and (c) variation in plasma gas flow rate. These studies will be useful for different material processing applications

Germination Response of MR 219 Rice Variety to Different Exposure Times and Periods of 2450 MHz Microwave Frequency

Directory of Open Access Journals (Sweden)

Daryush Talei

2013-01-01

Full Text Available Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR, germination percentage (GP, and mean germination time (MGT were analyzed by exposing its seeds to 2450 MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GPa3 ranged from 93% to 98%, they failed to reduce the MGTa3. The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length. Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity.

Deposition of organosilicone thin film from hexamethyldisiloxane (HMDSO) with 50 kHz/33 MHz dual-frequency atmospheric-pressure plasma jet

Science.gov (United States)

Li, Jiaojiao; Yuan, Qianghua; Chang, Xiaowei; Wang, Yong; Yin, Guiqin; Dong, Chenzhong

2017-04-01

The deposition of organosilicone thin films from hexamethyldisiloxane(HMDSO) by using a dual-frequency (50 kHz/33 MHz) atmospheric-pressure micro-plasma jet with an admixture of a small volume of HMDSO and Ar was investigated. The topography was measured by using scanning electron microscopy. The chemical bond and composition of these films were analyzed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy. The results indicated that the as-deposited film was constituted by silicon, carbon, and oxygen elements, and FTIR suggested the films are organosilicon with the organic component (-CH x ) and hydroxyl functional group(-OH) connected to the Si-O-Si backbone. Thin-film hardness was recorded by an MH-5-VM Digital Micro-Hardness Tester. Radio frequency power had a strong impact on film hardness and the hardness increased with increasing power.

A Multiple-Channel Sub-Band Transient Detection System

Energy Technology Data Exchange (ETDEWEB)

David A. Smith

1998-11-01

We have developed a unique multiple-channel sub-band transient detection system to record transient electromagnetic signals in carrier-dominated radio environments; the system has been used to make unique observations of weak, transient HF signals. The detection system has made these observations possible through improved sensitivity compared to conventional broadband transient detection systems; the sensitivity improvement is estimated to be at least 20 dB. The increase in sensitivity has been achieved through subdivision of the band of interest (an 18 MHz tunable bandwidth) into eight sub-band independent detection channels, each with a 400 kHz bandwidth and its own criteria. The system generates a system trigger signal when a predetermined number of channels (typically five) trigger within a predetermined window of time (typically 100 ~s). Events are recorded with a broadband data acquisition system sampling at 50 or 100 Msample/s, so despite the fact that the detection system operates on portions of the signal confined to narrow bands, data acquisition is broadband. Between May and September of 1994, the system was used to detect and record over six thousand transient events in the frequency band from 3 to 30 MHz. Approximately 500 of the events have been characterized as paired bursts of radio noise with individual durations of 2 to 10 ps and separations between the bursts of 5 to 160 ps. The paired transients are typically 5 to 40 dB brighter than the background electromagnetic spectrum between carrier signals. We have termed these events SubIonospheric Pulse Pairs (SIPPS) and presently have no explanation as to their source. Our observations of SIPPS resemble observations of TransIonospheric Pulse Pairs (TIPPs) recorded by the Blackboard instrument on the ALEXIS satellite; the source of TIPP events is also unknown. Most of the recorded SIPP events do not exhibit frequency dispersion, implying propagation along a line-of-sight (groundwave) path; but seven of

Practically Efficient Blind Speech Separation Using Frequency Band Selection Based on Magnitude Squared Coherence and a Small Dodecahedral Microphone Array

Directory of Open Access Journals (Sweden)

Kazunobu Kondo

2012-01-01

Full Text Available Small agglomerative microphone array systems have been proposed for use with speech communication and recognition systems. Blind source separation methods based on frequency domain independent component analysis have shown significant separation performance, and the microphone arrays are small enough to make them portable. However, the level of computational complexity involved is very high because the conventional signal collection and processing method uses 60 microphones. In this paper, we propose a band selection method based on magnitude squared coherence. Frequency bands are selected based on the spatial and geometric characteristics of the microphone array device which is strongly related to the dodecahedral shape, and the selected bands are nonuniformly spaced. The estimated reduction in the computational complexity is 90% with a 68% reduction in the number of frequency bands. Separation performance achieved during our experimental evaluation was 7.45 (dB (signal-to-noise ratio and 2.30 (dB (cepstral distortion. These results show improvement in performance compared to the use of uniformly spaced frequency band.

Fully integrated low-loss band-pass filters for wireless applications

International Nuclear Information System (INIS)

Rais-Zadeh, M; Kapoor, A; Lavasani, H M; Ayazi, F

2009-01-01

Fully integrated low insertion loss micromachined band-pass filters are designed and fabricated on the silicon substrate (ρ = 10–20 Ω cm, ε r = 11.9) for UHF applications. Filters are made of silver, which has the highest conductivity of all metals, to minimize the ohmic loss. A detailed analysis for realizing low insertion loss and high out-of-band rejection filters using elliptic magnitude characteristics is presented, and a comprehensive model to take into account inductive parasitics of the interconnects is developed. Temperature characteristics of the filters are measured and show stable performance. The presented filters are different from the previously reported lumped element filters in that all filters are fully integrated on silicon substrate and occupy a remarkably smaller die area. Two filters are fabricated using the silver micromachining technique with center frequencies at 1.05 and 1.35 GHz. The filters have a constant 3 dB bandwidth of 300 MHz (28.6% and 22.2%) and an insertion loss of 1.4–1.7 dB. The low insertion loss and CMOS compatibility make the presented filters suitable candidates for radio frequency integrated circuits

Observation of band gaps in the gigahertz range and deaf bands in a hypersonic aluminum nitride phononic crystal slab

Science.gov (United States)

Gorisse, M.; Benchabane, S.; Teissier, G.; Billard, C.; Reinhardt, A.; Laude, V.; Defaÿ, E.; Aïd, M.

2011-06-01

We report on the observation of elastic waves propagating in a two-dimensional phononic crystal composed of air holes drilled in an aluminum nitride membrane. The theoretical band structure indicates the existence of an acoustic band gap centered around 800 MHz with a relative bandwidth of 6.5% that is confirmed by gigahertz optical images of the surface displacement. Further electrical measurements and computation of the transmission reveal a much wider attenuation band that is explained by the deaf character of certain bands resulting from the orthogonality of their polarization with that of the source.

Development of a Magnetron Resonance Frequency Auto Tuning System for Medical Xband [9300 MHz] RF Linear Accelerator

Energy Technology Data Exchange (ETDEWEB)

Cha, Sung Su; Lee, Byung Cheol [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Yujong; Park, Hyung Dal; Lee, Byeong-No; Joo, Youngwoo; Cha, Hyungki; Lee, Soo Min; Song, Ki Baek [KAERI, Daejeon (Korea, Republic of); Lee, Seung Hyun [Sungkyunkwan University, Suwon (Korea, Republic of)

2015-05-15

The total components of the accelerator are the magnetron, electron gun, accelerating structure, a set of solenoid magnets, four sets of steering coils, a modulator, and a circulator. One of the accelerator components of the accelerating structure is made of oxygen-free high-conductivity copper (OFHC), and its volume is changed according to the ambient temperature. As the volume changes, the resonant frequency of the accelerating structure is changed. Accordingly, the resonance frequency is mismatched between the source of the magnetron and the accelerating structure. An automatic frequency tuning system is automatically matched with the resonant frequency of the magnetron and accelerating structure, which allows a high output power and reliable accelerator operation. An automatic frequency tuning system is composed of a step motor control part for correcting the frequency of the source and power measuring parts, i.e., the forward and reflected power between the magnetron and accelerating structure. In this paper, the design, fabrication, and RF power test of the automatic frequency tuning system for the X-band linac are presented. A frequency tuning system was developed to overcome an unstable accelerator operation owing to the frequency mismatch between the magnetron and accelerating structure. The frequency measurement accuracy is 100 kHz and 0.72 degree per pulse.

Band-notched spiral antenna

Science.gov (United States)

Jeon, Jae; Chang, John

2018-03-13

A band-notched spiral antenna having one or more spiral arms extending from a radially inner end to a radially outer end for transmitting or receiving electromagnetic radiation over a frequency range, and one or more resonance structures positioned adjacent one or more segments of the spiral arm associated with a notch frequency band or bands of the frequency range so as to resonate and suppress the transmission or reception of electromagnetic radiation over said notch frequency band or bands.

Dual-function photonic integrated circuit for frequency octo-tupling or single-side-band modulation.

Science.gov (United States)

Hasan, Mehedi; Maldonado-Basilio, Ramón; Hall, Trevor J

2015-06-01

A dual-function photonic integrated circuit for microwave photonic applications is proposed. The circuit consists of four linear electro-optic phase modulators connected optically in parallel within a generalized Mach-Zehnder interferometer architecture. The photonic circuit is arranged to have two separate output ports. A first port provides frequency up-conversion of a microwave signal from the electrical to the optical domain; equivalently single-side-band modulation. A second port provides tunable millimeter wave carriers by frequency octo-tupling of an appropriate amplitude RF carrier. The circuit exploits the intrinsic relative phases between the ports of multi-mode interference couplers to provide substantially all the static optical phases needed. The operation of the proposed dual-function photonic integrated circuit is verified by computer simulations. The performance of the frequency octo-tupling and up-conversion functions is analyzed in terms of the electrical signal to harmonic distortion ratio and the optical single side band to unwanted harmonics ratio, respectively.

Cytogenetic studies in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (835.62 MHz, FDMA).

Science.gov (United States)

Vijayalaxmi; Leal, B Z; Meltz, M L; Pickard, W F; Bisht, K S; Roti Roti JL; Straube, W L; Moros, E G

2001-01-01

Freshly collected peripheral blood samples from four healthy human volunteers were diluted with RPMI 1640 tissue culture medium and exposed in sterile T-75 tissue culture flasks in vitro for 24 h to 835.62 MHz radiofrequency (RF) radiation, a frequency employed for customer-to-base station transmission of cellular telephone communications. An analog signal was used, and the access technology was frequency division multiple access (FDMA, continuous wave). A nominal net forward power of 68 W was used, and the nominal power density at the center of the exposure flask was 860 W/m(2). The mean specific absorption rate in the exposure flask was 4.4 or 5.0 W/kg. Aliquots of diluted blood that were sham-exposed or exposed in vitro to an acute dose of 1.50 Gy of gamma radiation were used as negative or positive controls. Immediately after the exposures, the lymphocytes were stimulated with a mitogen, phytohemagglutinin, and cultured for 48 or 72 h to determine the extent of genetic damage, as assessed from the frequencies of chromosomal aberrations and micronuclei. The extent of alteration in the kinetics of cell proliferation was determined from the mitotic indices in 48-h cultures and from the incidence of binucleate cells in 72-h cultures. The data indicated no significant differences between RF-radiation- and sham-exposed lymphocytes with respect to mitotic indices, incidence of exchange aberrations, excess fragments, binucleate cells, and micronuclei. In contrast, the response of the lymphocytes exposed to gamma radiation was significantly different from both RF-radiation- and sham-exposed cells for all of these indices. Thus, under the experimental conditions tested, there is no evidence for the induction of chromosomal aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to 835.62 MHz RF radiation at SARs of 4.4 or 5.0 W/kg.

Can comodulation masking release occur when frequency changes could promote perceptual segregation of the on-frequency and flanking bands?

DEFF Research Database (Denmark)

Verhey, Jesko L; Epp, Bastian; Stasiak, Arkadiusz

2013-01-01

A common characteristic of natural sounds is that the level fluctuations in different frequency regions are coherent. The ability of the auditory system to use this comodulation is shown when a sinusoidal signal is masked by a masker centred at the signal frequency (on-frequency masker, OFM......) and one or more off-frequency components, commonly referred to as flanking bands (FBs). In general, the threshold of the signal masked by comodulated masker components is lower than when masked by masker components with uncorrelated envelopes or in the presence of the OFM only. This effect is commonly...... referred to as comodulation masking release (CMR). The present study investigates if CMR is also observed for a sinusoidal signal embedded in the OFM when the centre frequencies of the FBs are swept over time with a sweep rate of one octave per second. Both a common change of different frequencies...

The very low-frequency band of heart rate variability represents the slow recovery component after a mental stress task.

Science.gov (United States)

Usui, Harunobu; Nishida, Yusuke

2017-01-01

The very low-frequency (VLF) band of heart rate variability (HRV) has different characteristics compared with other HRV components. Here we investigated differences in HRV changes after a mental stress task. After the task, the high-frequency (HF) band and ratio of high- to low-frequency bands (LF/HF) immediately returned to baseline. We evaluated the characteristics of VLF band changes after a mental stress task. We hypothesized that the VLF band decreases during the Stroop color word task and there would be a delayed recovery for 2 h after the task (i.e., the VLF change would exhibit a "slow recovery"). Nineteen healthy, young subjects were instructed to rest for 10 min, followed by a Stroop color word task for 20 min. After the task, the subjects were instructed to rest for 120 min. For all subjects, R-R interval data were collected; analysis was performed for VLF, HF, and LF/HF ratio. HRV during the rest time and each 15-min interval of the recovery time were compared. An analysis of the covariance was performed to adjust for the HF band and LF/HF ratio as confounding variables of the VLF component. HF and VLF bands significantly decreased and the LF/HF ratio significantly increased during the task compared with those during rest time. During recovery, the VLF band was significantly decreased compared with the rest time. After the task, the HF band and LF/HF ratio immediately returned to baseline and were not significantly different from the resting values. After adjusting for HF and LF/HF ratio, the VLF band had significantly decreased compared with that during rest. The VLF band is the "slow recovery" component and the HF band and LF/HF ratio are the "quick recovery" components of HRV. This VLF characteristic may clarify the unexplained association of the VLF band in cardiovascular disease prevention.

Investigation of Capacitively Coupled Argon Plasma Driven by Dual-Frequency with Different Frequency Configurations

International Nuclear Information System (INIS)

Yu Yiqing; Xin Yu; Ning Zhaoyuan; Lu Wenqi

2011-01-01

Low pressure argon dual-frequency (DF) capacitively coupled plasma (CCP) is generated by using different frequency configurations, such as 13.56/2, 27/2, 41/2, and 60/2 MHz. Characteristics of the plasma are investigated by using a floating double electrical probe and optical emission spectroscopy (OES). It is shown that in the DF-CCPs, the electron temperature T e decreases with the increase in exciting frequency, while the onset of 2 MHz induces a sudden increase in T e and the electron density increases basically with the increase in low frequency (LF) power. The intensity of 750.4 nm emission line increases with the LF power in the case of 13.56/2 MHz, while different tendencies of line intensity with the LF power appear for other configurations. The reason for this is also discussed.

LOW-FREQUENCY IMAGING OF FIELDS AT HIGH GALACTIC LATITUDE WITH THE MURCHISON WIDEFIELD ARRAY 32 ELEMENT PROTOTYPE

Energy Technology Data Exchange (ETDEWEB)

Williams, Christopher L.; Hewitt, Jacqueline N.; Levine, Alan M. [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA (United States); De Oliveira-Costa, Angelica; Hernquist, Lars L.; Bernardi, Gianni [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Bowman, Judd D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Briggs, Frank H. [Research School of Astronomy and Astrophysics, The Australian National University, Canberra (Australia); Gaensler, B. M.; Mitchell, Daniel A.; Subrahmanyan, Ravi; Sadler, Elaine M. [ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia); Morales, Miguel F. [Department of Physics, University of Washington, Seattle, WA (United States); Sethi, Shiv K. [Raman Research Institute, Bangalore (India); Arcus, Wayne; Crosse, Brian W. [International Centre for Radio Astronomy Research, Curtin University, Perth (Australia); Barnes, David G. [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne (Australia); Bunton, John D. [CSIRO Astronomy and Space Science, Epping (Australia); Cappallo, Roger C.; Corey, Brian E., E-mail: clmw@mit.edu [MIT Haystack Observatory, Westford, MA (United States); and others

2012-08-10

The Murchison Widefield Array (MWA) is a new low-frequency, wide-field-of-view radio interferometer under development at the Murchison Radio-astronomy Observatory in Western Australia. We have used a 32 element MWA prototype interferometer (MWA-32T) to observe two 50 Degree-Sign diameter fields in the southern sky, covering a total of {approx}2700 deg{sup 2}, in order to evaluate the performance of the MWA-32T, to develop techniques for epoch of reionization experiments, and to make measurements of astronomical foregrounds. We developed a calibration and imaging pipeline for the MWA-32T, and used it to produce {approx}15' angular resolution maps of the two fields in the 110-200 MHz band. We perform a blind source extraction using these confusion-limited images, and detect 655 sources at high significance with an additional 871 lower significance source candidates. We compare these sources with existing low-frequency radio surveys in order to assess the MWA-32T system performance, wide-field analysis algorithms, and catalog quality. Our source catalog is found to agree well with existing low-frequency surveys in these regions of the sky and with statistical distributions of point sources derived from Northern Hemisphere surveys; it represents one of the deepest surveys to date of this sky field in the 110-200 MHz band.

Cyclic stress at mHz frequencies aligns fibroblasts in direction of zero strain.

Directory of Open Access Journals (Sweden)

Uta Faust

Full Text Available Recognition of external mechanical signals is vital for mammalian cells. Cyclic stretch, e.g. around blood vessels, is one such signal that induces cell reorientation from parallel to almost perpendicular to the direction of stretch. Here, we present quantitative analyses of both, cell and cytoskeletal reorientation of umbilical cord fibroblasts. Cyclic strain of preset amplitudes was applied at mHz frequencies. Elastomeric chambers were specifically designed and characterized to distinguish between zero strain and minimal stress directions and to allow accurate theoretical modeling. Reorientation was only induced when the applied stretch exceeded a specific amplitude, suggesting a non-linear response. However, on very soft substrates no mechanoresponse occurs even for high strain. For all stretch amplitudes, the angular distributions of reoriented cells are in very good agreement with a theory modeling stretched cells as active force dipoles. Cyclic stretch increases the number of stress fibers and the coupling to adhesions. We show that changes in cell shape follow cytoskeletal reorientation with a significant temporal delay. Our data identify the importance of environmental stiffness for cell reorientation, here in direction of zero strain. These in vitro experiments on cultured cells argue for the necessity of rather stiff environmental conditions to induce cellular reorientation in mammalian tissues.

Status of 174 MHz RF system for BEP

International Nuclear Information System (INIS)

Biryuchevsky, Yu.A.; Gorniker, E.I.; Kendjebulatov, E.K.; Krutikhin, S.A.; Kurkin, G.Ya.; Petrov, V.M.; Pilan, A.M.

2012-01-01

The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system.

Integrated Common Radio Resource Management with Spectrum Aggregation over Non-Contiguous Frequency Bands

DEFF Research Database (Denmark)

Cabral, Orlando; Meucci, Filippo; Mihovska, Albena D.

2011-01-01

This paper proposes an integrated Common Radio Resource Management (iCRRM). The iCRRM performs classic CRRM functionalities jointly with Spectrum Aggregation (SA), being able to switch users between non-contiguous frequency bands. The SA scheduling is obtained with an optimised General Multi...

The VLA Low-band Ionosphere and Transient Experiment (VLITE)

Science.gov (United States)

Clarke, Tracy; Peters, Wendy; Brisken, Walter; Giacintucci, Simona; Kassim, Namir; Polisensky, Emil; Helmboldt, Joseph; Richards, Emily E.; Erickson, Alan; Ray, Paul S.; Kerr, Matthew T.; Deneva, Julia; Coburn, William; Huber, Robert; Long, Jeff

2018-01-01

The VLA Low-band Ionosphere and Transient Experiment (VLITE, http://vlite.nrao.edu/ ) is a commensal low-frequency observing system that has been operational on the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array (VLA) since late 2014. The separate optical paths of the prime-focus sub-GHz dipole feeds and the Cassegrain-focus 1-50 GHz feeds allow both systems to operate simultaneously with independent correlators. The initial 2.5 years of VLITE operation provided real-time correlation of 10 antennas across the 320-384 MHz band with a total observing time approaching 12,000 hours. During the summer of 2017, VLITE was upgraded to a total of 16 antennas (more than doubling the number of baselines) with enhanced correlator capabilities to enable correlation of the on-the-fly observing mode being used for the new NRAO VLA Sky Survey (VLASS).We present an overview of the VLITE system, including highlights of the complexities of a commensal observing program, sparse-array challenges, and scientific capabilities from our science-ready data pipeline. In the longer term, we seek a path to broadband expansion across all VLA antennas to develop a powerful new LOw Band Observatory (LOBO).

Self-oscillating Galvanic Isolated Bidirectional Very High Frequency DC-DC Converter

DEFF Research Database (Denmark)

Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Knott, Arnold

2015-01-01

This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has to be synch......This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has...

Design of high–order HTS dual–band bandpass filters with receiver subsystem for future mobile communication systems

Energy Technology Data Exchange (ETDEWEB)

Sekiya, N., E-mail: nsekiya@yamanashi.ac.jp

2016-08-15

Highlights: • We have developed two high-order HTS dual-band BPFs with a receiver subsystem for future mobile communication systems. • We developed a method for flexibly adjusting the coupling coefficient for the two passbands. • We demonstrated an HTS dual-band BPF receiver subsystem that uses a pulse tube cryocooler and a wideband LNA. • The proposed BPF is evaluated by simulation and measurement with good agreement. - Abstract: We have developed two high-order high-temperature superconducting (HTS) dual-band bandpass filters (BPFs) with a receiver subsystem for future mobile communication systems. They feature stub-loaded hair-pin resonators with two types of microstrip lines between them. One has a six-pole design, and the other has an eight-pole design. Both were designed to operate at 2.15 GHz with a 43-MHz (2%) bandwidth for the lower passband and at 3.50 GHz with a 70-MHz (2%) bandwidth for the upper one. They were fabricated using YBa{sub 2}Cu{sub 3}O{sub y} thin film on a CeO{sub 2}-bufferd r-Al{sub 2}O{sub 3} substrate. The measured results for both filters agree well with the simulated ones. The HTS dual-band BPF receiver subsystem uses a pulse tube cryocooler and a wideband low noise amplifier (LNA). We measured the frequency response of the six-pole dual-band BPF with and without a wideband LNA with a gain of 10 dB. The measured return losses were close.

Fully inkjet printed wide band cantor fractal antenna for RF energy harvesting application

KAUST Repository

Bakytbekov, Azamat

2017-06-07

Energy harvesting from ambient RF signals is feasible, particularly from the GSM bands such as 900MHz, 1800MHz and the 3G band at 2.1GHz. This requires a wideband receive antenna which can cover all these bands with decent gain performance and an omnidirectional radiation pattern. In this work, a novel Cantor fractal antenna has been designed which fulfills the above mentioned performance requirements. Antenna has been realized through a combination of 3D inkjet printing of plastic substrate and 2D inkjet printing of metallic nanoparticles based ink. The stable impedance and radiation performance of the antenna over a bandwidth of 0.8GHz to 2.2GHz (93 %) shows the feasibility of its employment in wide band energy harvesting applications.

Rotational structure of the five lowest frequency fundamental vibrational states of dimethylsulfoxide

Science.gov (United States)

Cuisset, Arnaud; Drumel, Marie-Aline Martin; Hindle, Francis; Mouret, Gaël; Sadovskií, Dmitrií A.

2013-10-01

We report on the successful extended analysis of the high-frequency (200-700 GHz) part of the gas phase (sub)mm-wave spectra of dimethylsulfoxide (DMSO). The spectrum was recorded at 100 kHz resolution using a solid state subTHz spectrometer. The five lowest energy fundamental vibrational states of DMSO with frequencies below 400 cm-1 were observed as sidebands along with the main 0←0 band. Neglecting the internal rotation of methyls, our rotational Hamiltonian reproduced the spectrum to the subMHz accuracy. We have found that the asymmetric bending state ν23 is the only low frequency fundamental vibrational state with the "anomalous" rotational structure uncovered in Cuisset et al. [1]. dmsomw 2013-09-04 15:03

Effect of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency

International Nuclear Information System (INIS)

Ding Xueyong; Li Hongfan; Lv Zhensu

2012-01-01

Based on the mode-coupling method, numerical analysis is presented to demonstrate the influence of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency. Results show that the interval between the band-gaps of the competing mode and the desired working mode is narrowed by use of positive-taper ripples, but is expanded if negative-taper ripples are employed, and the influence of the negative-taper ripples is obviously more advantageous than the positive-taper ripples; the band-gap overlap of modes can be efficiently separated by use of negative-taper ripples. The residual side-lobes of the frequency response in a coaxial Bragg structure with ripple taper also can be effectively suppressed by employing the windowing-function technique. These peculiarities provide potential advantage in constructing a coaxial Bragg cavity with high quality factor for single higher-order-mode operation of a high-power free-electron maser in the terahertz frequency range.

Precise fabrication of X-band accelerating structure

International Nuclear Information System (INIS)

Higo, T.; Sakai, H.; Higashi, Y.; Koike, S.; Takatomi, T.

1994-01-01

An accelerating structure with a/λ=0.16 is being fabricated to study a precise fabrication method. A frequency control of each cell better than 10 -4 level is required to realize a detuned structure. The present machining level is nearly 1 MHz/11.4 GHz in relative frequency error, which just satisfies the above requirement. To keep this machining precision, the diffusion bonding technique is found preferable to join the cells. Various diffusion conditions were tried. The frequency change can be less than 1 MHz/11.4 GHz and it can be controlled well better than that. (author)

A 3D printed dual GSM band near isotropic on-package antenna

KAUST Repository

Zhen, Su

2017-10-25

In this paper, we propose an on-package dual band monopole antenna with near-isotropic radiation pattern for GSM mobile applications. The proposed antenna is well matched for both GSM 900 and 1800 bands and provides decent gain for both the bands (1.67 and 3.27 dBi at 900 MHz and 1800 MHz respectively). The antenna is printed with silver ink on a 3D printed polymer based package. The package houses the GSM electronics and the battery. By optimizing the antenna arms width and length, a near-isotropic radiation pattern is achieved. Unlike the published isotropic antennas which are either single band or large in size, the proposed antenna covers both GSM bands with required bandwidth and is only half wavelength long. The design is low cost and highly suitable for various GSM applications such as localization, in additional to conventional communication applications.

HERA Broadband Feed Design for Low-Frequency Radio Astronomy

Science.gov (United States)

Garza, Sierra; Trung, Vincent; Ewall-Wice, Aaron Michael; Li, Jianshu; Hewitt, Jacqueline; Riley, Daniel; Bradley, Richard F.; Makhija, Krishna

2018-01-01

As part of the Hydrogen Epoch of Reionization Array (HERA) project, we are designing a broadband low-frequency radio feed to extend the bandwidth from 100-200 MHz to 50-220 MHz. By extending the lower-limit to 50 MHz, we hope to detect the signatures of the first black holes heating the hydrogen gas in the intergalactic medium.The isolation of a very faint signal from vastly brighter foregrounds sets strict requirements on antenna spectral smoothness, polarization purity, forward gain, and internal reflections. We are currently working to meet these requirements with a broad-band sinuous antenna feed suspended over the 14-m parabolic HERA dish, using a combination of measurements and simulations to verify the performance of our design.A sinuous feed has been designed and simulated with Computer Simulation Technology (CST) software. We will present the construction of a prototype sinuous antenna and measurements of its reflection coefficient, S11, including laboratory characterization of baluns. Our measurements agree well with the CST simulations of the antenna’s performance, giving us confidence in our ability to model the feed and ensure that it meets the requirements of a 21cm cosmology measurement.

Improved capacitance sensor with variable operating frequency for scanning capacitance microscopy

International Nuclear Information System (INIS)

Kwon, Joonhyung; Kim, Joonhui; Jeong, Jong-Hwa; Lee, Euy-Kyu; Seok Kim, Yong; Kang, Chi Jung; Park, Sang-il

2005-01-01

Scanning capacitance microscopy (SCM) has been gaining attention for its capability to measure local electrical properties in doping profile, oxide thickness, trapped charges and charge dynamics. In many cases, stray capacitance produced by different samples and measurement conditions affects the resonance frequency of a capacitance sensor. The applications of conventional SCM are critically limited by the fixed operating frequency and lack of tunability in its SCM sensor. In order to widen SCM application to various samples, we have developed a novel SCM sensor with variable operating frequency. By performing variable frequency sweep over the band of 160 MHz, the SCM sensor is tuned to select the best and optimized resonance frequency and quality factor for each sample measurement. The fundamental advantage of the new variable frequency SCM sensor was demonstrated in the SCM imaging of silicon oxide nano-crystals. Typical sensitivity of the variable frequency SCM sensor was found to be 10 -19 F/V

A search for interplanetary scintillation of Cygnus A at 81.5 MHz

International Nuclear Information System (INIS)

Tsien, S.C.; Duffett-Smith, P.J.

1982-01-01

IPS observations of Cygnus A at 81.5 MHz with the Cambridge 3.6-hectare array set an upper limit on the scintillation of 0.07 per cent of the total flux density. This suggests that the hotspots seen at high frequencies are much less prominent at low frequencies. (author)

Acoustic transfer function of cavity and its application to rapid evaluation of sound field at low frequency band

Institute of Scientific and Technical Information of China (English)

YIN Gang; CHEN Hualing; HU Xuanli; HUANG Xieqing

2001-01-01

A new method to obtain numerical solution of Acoustic Transfer Function (ATF) by BEM is presented. For a simply supported panel backed by a rectangular cavity at low frequency band (0-200 Hz), the frequency property of ATF is analyzed. The relation between the accuracy of the rapid evaluation of sound field and the discretization schemes of the vibrational panel is discussed. The result shows that the method to obtain ATF and the rapid evaluation of sound field using the ATF is suitable to low frequency band. If an appropriate discretization scheme is choosed based on the frequency involved and the effort to obtain ATF, the accuracy of the rapid evaluation of sound field is acceptable.

47 CFR 90.477 - Interconnected systems.

Science.gov (United States)

2010-10-01

... part and medical emergency systems in the 450-470 MHz band, interconnection will be permitted only... operating on frequencies in the bands below 800 MHz are not subject to the interconnection provisions of...

120 MW, 800 MHz Magnicon for a Future Muon Collider

International Nuclear Information System (INIS)

Jay L. Hirshfield

2005-01-01

Development of a pulsed magnicon at 800 MHz was carried out for the muon collider application, based on experience with similar amplifiers in the frequency range between 915 MHz and 34.3 GHz. Numerical simulations using proven computer codes were employed for the conceptual design, while established design technologies were incorporated into the engineering design. A cohesive design for the 800 MHz magnicon amplifier was carried out, including design of a 200 MW diode electron gun, design of the magnet system, optimization of beam dynamics including space charge effects in the transient and steady-state regimes, design of the drive, gain, and output cavities including an rf choke in the beam exit aperture, analysis of parasitic oscillations and design means to eliminate them, and design of the beam collector capable of 20 kW average power operation

Exploiting elastic anharmonicity in aluminum nitride matrix for phase-synchronous frequency reference generation

Science.gov (United States)

Ghatge, Mayur; Tabrizian, Roozbeh

2018-03-01

A matrix of aluminum-nitride (AlN) waveguides is acoustically engineered to realize electrically isolated phase-synchronous frequency references through nonlinear wave-mixing. AlN rectangular waveguides are cross-coupled through a periodically perforated plate that is engineered to have a wide acoustic bandgap around a desirable frequency ( f1≈509 MHz). While the coupling plate isolates the matrix from resonant vibrations of individual waveguide constituents at f1, it is transparent to the third-order harmonic waves (3f1) that are generated through nonlinear wave-mixing. Therefore, large-signal excitation of the f1 mode in a constituent waveguide generates acoustic waves at 3f1 with an efficiency defined by elastic anharmonicity of the AlN film. The phase-synchronous propagation of the third harmonic through the matrix is amplified by a high quality-factor resonance mode at f2≈1529 MHz, which is sufficiently close to 3f1 (f2 ≅ 3f1). Such an architecture enables realization of frequency-multiplied and phase-synchronous, yet electrically and spectrally isolated, references for multi-band/carrier and spread-spectrum wireless communication systems.

SIMULTANEOUS OBSERVATIONS OF GIANT PULSES FROM PULSAR PSR B0031-07 AT 38 AND 74 MHz

Energy Technology Data Exchange (ETDEWEB)

Tsai, Jr-Wei; Simonetti, John H.; Bear, Brandon [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Gough, Jonathan D. [Department of Chemistry, Lehman College, CUNY, Bronx, NY 10468 (United States); Newton, Joseph R. [Department of Chemistry and Physics, Augusta University, Augusta, GA 30912 (United States); Kavic, Michael [Department of Physics, Long Island University, Brooklyn, NY 11201 (United States)

2016-03-15

The first station of the Long Wavelength Array was used to study PSR B0031-07 with simultaneous observations at 38 and 74 MHz. We found that 158 (0.35%) of the observed pulses at 38 MHz and 221 (0.49%) of the observed pulses at 74 MHz qualified as giant pulses (GPs) in a total of 12 hr of observations. GPs are defined as having flux densities of a factor of ≥90 times that of an average pulse (AP) at 38 MHz and ≥80 times that of an AP at 74 MHz. The cumulative distribution of pulse strength follows a power law, with an index of −4.2 at 38 MHz and −4.9 at 74 MHz. This distribution has a much more gradual slope than would be expected if observing the tail of a Gaussian distribution of normal pulses. The dispersion measure (DM) value which resulted in the largest signal to noise for dedispersed pulses was DM = 10.9 pc cm{sup −3}. No other transient pulses were detected in the data in the wide DM range from 1 to 5000 pc cm{sup −3}. There were 12 GPs detected within the same period from both 38 and 74 MHz, meaning that the majority of them are not generated in a wide band.

Compact MIMO Microstrip Antennas for USB Dongle Operating in 2.5–2.7 GHz Frequency Band

Directory of Open Access Journals (Sweden)

Vladimir Ssorin

2012-01-01

Full Text Available This paper considers design of microstrip MIMO antennas for an LTE/WiMAX USB dongle operating in the 2.5–2.7 GHz frequency band. The MIMO system includes two antenna elements with an additional requirement of high isolation between them that is especially difficult to realize due to size limitations of a USB dongle. Three approaches to achieve the needed system characteristics using microstrip PCB antennas are proposed. For the first design, high port-to-port isolation is achieved by using a decoupling techniques based on a direct connection of the antenna elements. For the second approach, high port-to-port isolation of the MIMO antenna system is realized by a lumped decorrelation capacitance between antenna elements feeding points. The third proposed antenna system does not use any special techniques, and high port-to-port isolation is achieved by using only the properties of a developed printed inverted-F antenna element. The designed MIMO antenna systems have the return loss S11 and the insertion loss S21 bandwidths of more than 200 MHz at the −8 dB level with the correlation coefficient lower than 0.1 and exhibit pattern diversity when different antenna elements are excited. Experimental measurements of the fabricated antenna systems proved the characteristics obtained from electromagnetic simulation.

Potential of Sub-GHz Wireless for Future IoT Wearables and Design of Compact 915 MHz Antenna

Directory of Open Access Journals (Sweden)

Adolfo Di Serio

2017-12-01

Full Text Available Internet of Things (IoT technology is rapidly emerging in medical applications as it offers the possibility of lower-cost personalized healthcare monitoring. At the present time, the 2.45 GHz band is in widespread use for these applications but in this paper, the authors investigate the potential of the 915 MHz ISM band in implementing future, wearable IoT devices. The target sensor is a wrist-worn wireless heart rate and arterial oxygen saturation (SpO2 monitor with the goal of providing efficient wireless functionality and long battery lifetime using a commercial Sub-GHz low-power radio transceiver. A detailed analysis of current consumption for various wireless protocols is also presented and analyzed. A novel 915 MHz antenna design of compact size is reported that has good resilience to detuning by the human body. The antenna also incorporates a matching network to meet the challenging bandwidth requirements and is fabricated using standard, low-cost FR-4 material. Full-Wave EM simulations are presented for the antenna placed in both free-space and on-body cases. A prototype antenna is demonstrated and has dimensions of 44 mm × 28 mm × 1.6 mm. The measured results at 915 MHz show a 10 dB return loss bandwidth of 55 MHz, a peak realized gain of − 2.37 dBi in free-space and − 6.1 dBi on-body. The paper concludes by highlighting the potential benefits of 915 MHz operation for future IoT devices.

Potential of Sub-GHz Wireless for Future IoT Wearables and Design of Compact 915 MHz Antenna.

Science.gov (United States)

Di Serio, Adolfo; Buckley, John; Barton, John; Newberry, Robert; Rodencal, Matthew; Dunlop, Gary; O'Flynn, Brendan

2017-12-22

Internet of Things (IoT) technology is rapidly emerging in medical applications as it offers the possibility of lower-cost personalized healthcare monitoring. At the present time, the 2.45 GHz band is in widespread use for these applications but in this paper, the authors investigate the potential of the 915 MHz ISM band in implementing future, wearable IoT devices. The target sensor is a wrist-worn wireless heart rate and arterial oxygen saturation (SpO2) monitor with the goal of providing efficient wireless functionality and long battery lifetime using a commercial Sub-GHz low-power radio transceiver. A detailed analysis of current consumption for various wireless protocols is also presented and analyzed. A novel 915 MHz antenna design of compact size is reported that has good resilience to detuning by the human body. The antenna also incorporates a matching network to meet the challenging bandwidth requirements and is fabricated using standard, low-cost FR-4 material. Full-Wave EM simulations are presented for the antenna placed in both free-space and on-body cases. A prototype antenna is demonstrated and has dimensions of 44 mm × 28 mm × 1.6 mm. The measured results at 915 MHz show a 10 dB return loss bandwidth of 55 MHz, a peak realized gain of - 2.37 dBi in free-space and - 6.1 dBi on-body. The paper concludes by highlighting the potential benefits of 915 MHz operation for future IoT devices.

Experimental performance assessment of the sub-band minimum variance beamformer for ultrasound imaging

DEFF Research Database (Denmark)

Diamantis, Konstantinos; Greenaway, Alan H.; Anderson, Tom

2017-01-01

Recent progress in adaptive beamforming techniques for medical ultrasound has shown that current resolution limits can be surpassed. One method of obtaining improved lateral resolution is the Minimum Variance (MV) beamformer. The frequency domain implementation of this method effectively divides...... the broadband ultrasound signals into sub-bands (MVS) to conform with the narrow-band assumption of the original MV theory. This approach is investigated here using experimental Synthetic Aperture (SA) data from wire and cyst phantoms. A 7 MHz linear array transducer is used with the SARUS experimental...... ultrasound scanner for the data acquisition. The lateral resolution and the contrast obtained, are evaluated and compared with those from the conventional Delay-and-Sum (DAS) beamformer and the MV temporal implementation (MVT). From the wire phantom the Full-Width-at-Half-Maximum (FWHM) measured at a depth...

Infrared Spectra of the 10-μm Bands of 1,2-Difluoroethane and 1,1,2-Trifluoroethane: Vibrationally Mediated Torsional Tunneling in 1,1,2-Trifluoroethane

Science.gov (United States)

Stone, Stephen C.; Miller, C. Cameron; Philips, Laura A.; Andrews, A. M.; Fraser, G. T.; Pate, B. H.; Xu, Li-Hong

1995-12-01

The 3-MHz-resolution infrared spectra of the 10-μm bands of thegaucheconformer of 1,2-difluoroethane (HFC152) and theC1-symmetry conformer of 1,1,2-trifluoroethane (HFC143) have been measured using a molecular-beam electric-resonance optothermal spectrometer with a tunable microwave-sideband CO2laser source. For 1,2-difluoroethane, two bands have been studied, the ν17B-symmetry C-F stretch at 1077.3 cm-1and the ν13B-symmetry CH2rock at 896.6 cm-1. Both bands are well fit to a asymmetric-rotor Hamiltonian to better than 0.5 MHz. The ν13band is effectively unperturbed, while the ν17band is weakly perturbed, as shown by the large change in centrifugal distortion constants from the ground state values. Two bands have also been studied for 1,1,2-trifluoroethane, the ν11symmetric CF2stretch at 1077.2 cm-1and the ν13C-C stretch at 905.1 cm-1. One of the two bands, ν11, is unperturbed and fit to near the experimental precision. The ν13vibration, on the other hand, is weakly perturbed by an interaction with a nearby state. This perturbation leads to a doubling or splitting of the lines, due to a perturbation-induced lifting of the degeneracy of the symmetric and antisymmetric tunneling states associated with tunneling between the two equivalentC1forms. For theJ,Kastates studied, the splittings are as large as 37 MHz. Combining this observation with published low-resolution far-infrared measurements of torsional sequence-band and hot-band frequencies and calculations from an empirical torsional potential allows us to identify the perturbing state as ν17+ 6ν18. Here, ν17is the CF2twist and ν18is the torsion. The matrix element responsible for this interaction exchanges eight vibrational quanta!

Experimental demonstrations in audible frequency range of band gap tunability and negative refraction in two-dimensional sonic crystal.

Science.gov (United States)

Pichard, Hélène; Richoux, Olivier; Groby, Jean-Philippe

2012-10-01

The propagation of audible acoustic waves in two-dimensional square lattice tunable sonic crystals (SC) made of square cross-section infinitely rigid rods embedded in air is investigated experimentally. The band structure is calculated with the plane wave expansion (PWE) method and compared with experimental measurements carried out on a finite extend structure of 200 cm width, 70 cm depth and 15 cm height. The structure is made of square inclusions of 5 cm side with a periodicity of L = 7.5 cm placed inbetween two rigid plates. The existence of tunable complete band gaps in the audible frequency range is demonstrated experimentally by rotating the scatterers around their vertical axis. Negative refraction is then analyzed by use of the anisotropy of the equi-frequency surface (EFS) in the first band and of a finite difference time domain (FDTD) method. Experimental results finally show negative refraction in the audible frequency range.

47 CFR 90.1203 - Eligibility.

Science.gov (United States)

2010-10-01

... are eligible to hold a Commission license for systems operating in the 4940-4990 MHz band. All of the... MOBILE RADIO SERVICES Regulations Governing Licensing and Use of Frequencies in the 4940-4990 MHz Band...

The very low-frequency band of heart rate variability represents the slow recovery component after a mental stress task.

Directory of Open Access Journals (Sweden)

Harunobu Usui

Full Text Available The very low-frequency (VLF band of heart rate variability (HRV has different characteristics compared with other HRV components. Here we investigated differences in HRV changes after a mental stress task. After the task, the high-frequency (HF band and ratio of high- to low-frequency bands (LF/HF immediately returned to baseline. We evaluated the characteristics of VLF band changes after a mental stress task. We hypothesized that the VLF band decreases during the Stroop color word task and there would be a delayed recovery for 2 h after the task (i.e., the VLF change would exhibit a "slow recovery". Nineteen healthy, young subjects were instructed to rest for 10 min, followed by a Stroop color word task for 20 min. After the task, the subjects were instructed to rest for 120 min. For all subjects, R-R interval data were collected; analysis was performed for VLF, HF, and LF/HF ratio. HRV during the rest time and each 15-min interval of the recovery time were compared. An analysis of the covariance was performed to adjust for the HF band and LF/HF ratio as confounding variables of the VLF component. HF and VLF bands significantly decreased and the LF/HF ratio significantly increased during the task compared with those during rest time. During recovery, the VLF band was significantly decreased compared with the rest time. After the task, the HF band and LF/HF ratio immediately returned to baseline and were not significantly different from the resting values. After adjusting for HF and LF/HF ratio, the VLF band had significantly decreased compared with that during rest. The VLF band is the "slow recovery" component and the HF band and LF/HF ratio are the "quick recovery" components of HRV. This VLF characteristic may clarify the unexplained association of the VLF band in cardiovascular disease prevention.

A novel pulse compression algorithm for frequency modulated active thermography using band-pass filter

Science.gov (United States)

Chatterjee, Krishnendu; Roy, Deboshree; Tuli, Suneet

2017-05-01

This paper proposes a novel pulse compression algorithm, in the context of frequency modulated thermal wave imaging. The compression filter is derived from a predefined reference pixel in a recorded video, which contains direct measurement of the excitation signal alongside the thermal image of a test piece. The filter causes all the phases of the constituent frequencies to be adjusted to nearly zero value, so that on reconstruction a pulse is obtained. Further, due to band-limited nature of the excitation, signal-to-noise ratio is improved by suppressing out-of-band noise. The result is similar to that of a pulsed thermography experiment, although the peak power is drastically reduced. The algorithm is successfully demonstrated on mild steel and carbon fibre reference samples. Objective comparisons of the proposed pulse compression algorithm with the existing techniques are presented.

Wavelet Based Characterization of Low Radio Frequency Solar Emissions

Science.gov (United States)

Suresh, A.; Sharma, R.; Das, S. B.; Oberoi, D.; Pankratius, V.; Lonsdale, C.

2016-12-01

Low-frequency solar radio observations with the Murchison Widefield Array (MWA) have revealed the presence of numerous short-lived, narrow-band weak radio features, even during quiet solar conditions. In their appearance in in the frequency-time plane, they come closest to the solar type III bursts, but with much shorter spectral spans and flux densities, so much so that they are not detectable with the usual swept frequency radio spectrographs. These features occur at rates of many thousand features per hour in the 30.72 MHz MWA bandwidth, and hence necessarily require an automated approach to determine robust statistical estimates of their properties, e.g., distributions of spectral widths, temporal spans, flux densities, slopes in the time-frequency plane and distribution over frequency. To achieve this, a wavelet decomposition approach has been developed for feature recognition and subsequent parameter extraction from the MWA dynamic spectrum. This work builds on earlier work by the members of this team to achieve a reliable flux calibration in a computationally efficient manner. Preliminary results show that the distribution of spectral span of these features peaks around 3 MHz, most of them last for less than two seconds and are characterized by flux densities of about 60% of the background solar emission. In analogy with the solar type III bursts, this non-thermal emission is envisaged to arise via coherent emission processes. There is also an exciting possibility that these features might correspond to radio signatures of nanoflares, hypothesized (Gold, 1964; Parker, 1972) to explain coronal heating.

Compact Dual-Band Dipole Antenna with Asymmetric Arms for WLAN Applications

Directory of Open Access Journals (Sweden)

Chung-Hsiu Chiu

2014-01-01

Full Text Available A dual-band dipole antenna that consists of a horn- and a C-shaped metallic arm is presented. Depending on the asymmetric arms, the antenna provides two −10 dB impedance bandwidths of 225 MHz (about 9.2% at 2.45 GHz and 1190 MHz (about 21.6% at 5.5 GHz, respectively. This feature enables it to cover the required bandwidths for wireless local area network (WLAN operation at the 2.4 GHz band and 5.2/5.8 GHz bands for IEEE 802.11 a/b/g standards. More importantly, the compact size (7 mm × 24 mm and good radiating performance of the antenna are profitable to be integrated with wireless communication devices on restricted RF-elements spaces.

Digital predistortion of 75–110 GHz W-band frequency multiplier for fiber wireless short range access systems

DEFF Research Database (Denmark)

Zhao, Ying; Deng, Lei; Pang, Xiaodan

2011-01-01

be effectively pre-compensated. Without using costly W-band components, a transmission system with 26km fiber and 4m wireless transmission operating at 99.6GHz is experimentally validated. Adjacent-channel power ratio (ACPR) improvements for IQ-modulated vector signals are guaranteed and transmission......We present a W-band fiber-wireless transmission system based on a nonlinear frequency multiplier for high-speed wireless short range access applications. By implementing a baseband digital signal predistortion scheme, intensive nonlinear distortions induced in a sextuple frequency multiplier can...... performances for fiber and wireless channels are studied. This W-band predistortion technique is a promising candidate for applications in high capacity wireless-fiber access systems....

Design, construction and tuning of S-band coupler for electron linear accelerator of institute for research in fundamental sciences (IPM E-linac)

International Nuclear Information System (INIS)

Ghasemi, F.; Abbasi Davani, F.; Lamehi Rachti, M.; Shaker, H.; Ahmadiannamin, S.

2015-01-01

Design and construction of an electron linear accelerator by Institute for Research in Fundamental Science (IPM) is considered as Iran’s first attempt to construct such an accelerator. In order to design a linear accelerating tube, after defining the accelerating tube and buncher geometries, RF input and output couplers must be designed. In this article, firstly, a brief report on the specifications of an S-band electron linear accelerator which is in progress in the school of particles and accelerators is presented and then, the design process and construction reports of the couplers required for this accelerator are described. Through performing necessary calculations and tuning the coupling factor and resonant frequency, couplers with desired specification have been fabricated by shrinking method. The final obtained coupling factor and resonant frequency have been respectively 1.05 and 2997 MHz for the first coupler, and 0.98 and 2996.9 MHz for the second one that are close to calculation results

An automatic frequency control system of 2-MeV electronic LINAC

International Nuclear Information System (INIS)

Hu Xue; Zhang Junqiang; Zhong Shaopeng; Zhao Minghua

2013-01-01

Background: In electronic LINAC, the magnetron is often used as power source. The output frequency of magnetron always changes with the environment and the frequency difference between the output of magnetron and the frequency of accelerator, which will result in the bad performance of LINAC systems. Purpose: To ensure the performance of the work of entire LINAC system effectively, an automatic frequency control system is necessary. Methods: A phase locked frequency discriminator is designed to discriminate the frequency of accelerator guide and magnetron, and analogue circuit is used to process the output signals of frequency discriminator unit. Results: Working with the automatic frequency control (AFC) system, the output frequency of magnetron can be controlled in the range of (2998 MHz, 2998 MHz + 70 kHz) and (2998 MHz, 2998 MHz - 30 kHz). Conclusions: Under the measurement and debug, the functionality of frequency discriminator unit and signal processor circuit is tested effectively. (authors)

A low-spurious fast-hopping MB-OFDM UWB synthesizer

Energy Technology Data Exchange (ETDEWEB)

Chen Danfeng; Li Wei; Li Ning; Ren Junyan, E-mail: w-li@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

2010-06-15

A frequency synthesizer for the ultra-wide band (UWB) group no. 1 is proposed. The synthesizer uses a phase-locked loop (PLL) and single-sideband (SSB) mixers to generate the three center frequencies of the first band group by mixing 4224 MHz with {+-}264 MHz and 792 MHz, respectively. A novel multi-QSSB mixer is designed to combine the function of frequency selection and frequency conversion for low power and high linearity. The synthesizer is fabricated in Jazz 0.18-{mu}m RF CMOS technology. The measured reference spur is as low as -69 dBc and the maximum spur is the LO leakage of -32 dBc. A low phase noise of -110 dBc/Hz - 1 MHz offset and an integrated phase noise of 1.86{sup 0} are achieved. The hopping time between different bands is less than 1.8 ns. The synthesizer consumes 30 mA from a 1.8 V supply. (semiconductor integrated circuits)

A low-spurious fast-hopping MB-OFDM UWB synthesizer

International Nuclear Information System (INIS)

Chen Danfeng; Li Wei; Li Ning; Ren Junyan

2010-01-01

A frequency synthesizer for the ultra-wide band (UWB) group no. 1 is proposed. The synthesizer uses a phase-locked loop (PLL) and single-sideband (SSB) mixers to generate the three center frequencies of the first band group by mixing 4224 MHz with ±264 MHz and 792 MHz, respectively. A novel multi-QSSB mixer is designed to combine the function of frequency selection and frequency conversion for low power and high linearity. The synthesizer is fabricated in Jazz 0.18-μm RF CMOS technology. The measured reference spur is as low as -69 dBc and the maximum spur is the LO leakage of -32 dBc. A low phase noise of -110 dBc/Hz - 1 MHz offset and an integrated phase noise of 1.86 0 are achieved. The hopping time between different bands is less than 1.8 ns. The synthesizer consumes 30 mA from a 1.8 V supply. (semiconductor integrated circuits)

An Unusual Rotationally Modulated Attenuation Band in the Jovian Hectometric Radio Emission Spectrum

Science.gov (United States)

Gurnett, D. A.; Kurth, W. S.; Menietti, J. D.; Persoon, A. M.

1998-01-01

A well-defined attenuation band modulated by the rotation of Jupiter has been found in the spectrum of Jovian hectometric radiation using data from the Galileo plasma wave instrument. The center frequency of this band usually occurs in the frequency range from about 1 to 3 MHz and the bandwidth is about 10 to 20 percent. The center frequency varies systematically with the rotation of Jupiter and has two peaks per rotation, the first at a system III longitude of about 50 deg, and the second at about 185 deg. It is now believed that the attenuation occurs as the ray path from a high-latitude cyclotron maser source passes approximately parallel to the magnetic field near the northern or southern edges of the Io L-shell. The peak at 50 deg system 3 longitude is attributed to radiation from a southern hemisphere source and the peak at 185 deg is from a northern hemisphere source. The attenuation is thought to be caused by coherent scattering or shallow angle reflection from field-aligned density irregularities near the Io L-shell. The narrow bandwidth indicates that the density irregularities are confined to a very narrow range of L values (Delta L = 0.2 to 0.4) near the Io L-shell.

Direct phase-locking of a 8.6-μm quantum cascade laser to a mid-IR optical frequency comb: application to precision spectroscopy of N2O.

Science.gov (United States)

Gambetta, Alessio; Cassinerio, Marco; Coluccelli, Nicola; Fasci, Eugenio; Castrillo, Antonio; Gianfrani, Livio; Gatti, Davide; Marangoni, Marco; Laporta, Paolo; Galzerano, Gianluca

2015-02-01

We developed a high-precision spectroscopic system at 8.6 μm based on direct heterodyne detection and phase-locking of a room-temperature quantum-cascade-laser against an harmonic, 250-MHz mid-IR frequency comb obtained by difference-frequency generation. The ∼30  dB signal-to-noise ratio of the detected beat-note together with the achieved closed-loop locking bandwidth of ∼500  kHz allows for a residual integrated phase noise of 0.78 rad (1 Hz-5 MHz), for an ultimate resolution of ∼21  kHz, limited by the measured linewidth of the mid-IR comb. The system was used to perform absolute measurement of line-center frequencies for the rotational components of the ν2 vibrational band of N2O, with a relative precision of 3×10(-10).

Increased parietal circuit-breaker activity in delta frequency band and abnormal delta/theta band connectivity in salience network in hyperacusis subjects.

Directory of Open Access Journals (Sweden)

Jae Joon Han

Full Text Available Recent studies have suggested that hyperacusis, an abnormal hypersensitivity to ordinary environmental sounds, may be characterized by certain resting-state cortical oscillatory patterns, even with no sound stimulus. However, previous studies are limited in that most studied subjects with other comorbidities that may have affected cortical activity. In this regard, to assess ongoing cortical oscillatory activity in idiopathic hyperacusis patients with no comorbidities, we compared differences in resting-state cortical oscillatory patterns between five idiopathic hyperacusis subjects and five normal controls. The hyperacusis group demonstrated significantly higher electrical activity in the right auditory-related cortex for the gamma frequency band and left superior parietal lobule (SPL for the delta frequency band versus the control group. The hyperacusis group also showed significantly decreased functional connectivity between the left auditory cortex (AC and left orbitofrontal cortex (OFC, between the left AC and left subgenual anterior cingulate cortex (sgACC for the gamma band, and between the right insula and bilateral dorsal anterior cingulate cortex (dACC and between the left AC and left sgACC for the theta band versus the control group. The higher electrical activity in the SPL may indicate a readiness of "circuit-breaker" activity to shift attention to forthcoming sound stimuli. Also, because of the disrupted salience network, consisting of the dACC and insula, abnormally increased salience to all sound stimuli may emerge, as a consequence of decreased top-down control of the AC by the dACC and dysfunctional emotional weight attached to auditory stimuli by the OFC. Taken together, abnormally enhanced attention and salience to forthcoming sound stimuli may render hyperacusis subjects hyperresponsive to non-noxious auditory stimuli.

CONSTRAINING THE SOLAR CORONAL MAGNETIC FIELD STRENGTH USING SPLIT-BAND TYPE II RADIO BURST OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C. [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore—560034 (India); Gopalswamy, N., E-mail: kishore@iiap.res.in [Code 671, Solar Physics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

2016-11-20

We report on low-frequency radio (85–35 MHz) spectral observations of four different type II radio bursts, which exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely associated with a whitelight coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the location of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the deprojected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the deprojected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa.

Waveguide circuit for LHRF heating in 'JT-60'

International Nuclear Information System (INIS)

Uehara, Kazuya; Saegusa, Mikio; Mizuno, Takenori; Sano, Keigo; Hara, Mitsuru; Oishi, Isamu; Kanai, Takao.

1985-01-01

As the heating method for attaining the critical condition in the critical plasma experiment apparatus 'JT-60' in the Japan Atomic Energy Research Institute, in addition to Joule heating, as the second heating method, neutral beam injection heating and high frequency heating have been adopted. For this high frequency heating, several tens to 200 MHz band of ICRF heating, several hundreds MHz to several GHz band of LHRF heating and several tens to 200 GHz band of ECR heating were considered, and in the JT-60, 100 MHz band (ICRF) and 2 GHz band (LHRF) have been adopted. Furukawa Electric Co., Ltd. has engaged in the development and manufacture of the waveguides of transmission system used for this high frequency heating through NEC Corp. This high frequency heating is to heat plasma by injecting high frequency radio waves into plasma proper, and reaches 10 MW for the whole high frequency heating. The system efficiently transmitting the radio waves of large power from a Klystron as a high frequency source to the JT-60 is the transmission system. The outline of the waveguides of the 2 GHz band transmission system and the individual performance of respective waveguides are reported. (Kako, I.)

High-frequency harmonic imaging of the eye

Science.gov (United States)

Silverman, Ronald H.; Coleman, D. Jackson; Ketterling, Jeffrey A.; Lizzi, Frederic L.

2005-04-01

Purpose: Harmonic imaging has become a well-established technique for ultrasonic imaging at fundamental frequencies of 10 MHz or less. Ophthalmology has benefited from the use of fundamentals of 20 MHz to 50 MHz. Our aim was to explore the ability to generate harmonics for this frequency range, and to generate harmonic images of the eye. Methods: The presence of harmonics was determined in both water and bovine vitreous propagation media by pulse/echo and hydrophone at a series of increasing excitation pulse intensities and frequencies. Hydrophone measurements were made at the focal point and in the near- and far-fields of 20 MHz and 40 MHz transducers. Harmonic images of the anterior segment of the rabbit eye were obtained by a combination of analog filtering and digital post-processing. Results: Harmonics were generated nearly identically in both water and vitreous. Hydrophone measurements showed the maximum second harmonic to be -5 dB relative to the 35 MHz fundamental at the focus, while in pulse/echo the maximum harmonic amplitude was -15dB relative to the fundamental. Harmonics were absent in the near-field, but present in the far-field. Harmonic images of the eye showed improved resolution. Conclusion: Harmonics can be readily generated at very high frequencies, and at power levels compliant with FDA guidelines for ophthalmology. This technique may yield further improvements to the already impressive resolutions obtainable in this frequency range. Improved imaging of the macular region, in particular, may provide significant improvements in diagnosis of retinal disease.

Expansion of lower-frequency locally resonant band gaps using a double-sided stubbed composite phononic crystals plate with composite stubs

Energy Technology Data Exchange (ETDEWEB)

Li, Suobin; Chen, Tianning [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Wang, Xiaopeng, E-mail: xpwang@mail.xjtu.edu.cn [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Li, Yinggang [Key Laboratory of High Performance Ship Technology of Ministry of Education, Wuhan University of Technology, Wuhan, 430070 (China); Chen, Weihua [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)

2016-06-03

We studied the expansion of locally resonant complete band gaps in two-dimensional phononic crystals (PCs) using a double-sided stubbed composite PC plate with composite stubs. Results show that the introduction of the proposed structure gives rise to a significant expansion of the relative bandwidth by a factor of 1.5 and decreases the opening location of the first complete band gap by a factor of 3 compared to the classic double-sided stubbed PC plate with composite stubs. Furthermore, more band gaps appear in the lower-frequency range (0.006). These phenomena can be attributed to the strong coupling between the “analogous rigid mode” of the stub and the anti-symmetric Lamb modes of the plate. The “analogous rigid mode” of the stub is produced by strengthening the localized resonance effect of the composite plates through the double-sided stubs, and is further strengthened through the introduction of composite stubs. The “analogous rigid mode” of the stubs expands the out-of-plane band gap, which overlaps with in-plane band gap in the lower-frequency range. As a result, the complete band gap is expanded and more complete band gaps appear. - Highlights: • Expansion of lower-frequency locally resonant BGs using novel composite phononic crystals plates. • The proposed structure expands the relative bandwidth 1.5 times compared to classic doubled-sided stubbed PC plates. • The opening location of the first complete BG decreases 3 times compared to the classic doubled-sided stubbed PC plates. • The concept “analogous rigid mode” is put forward to explain the expansion of lower-frequency BGs.

Dual-Frequency Impedance Transformer Using Coupled-Line For Ultra-High Transforming Ratio

Directory of Open Access Journals (Sweden)

R. K. Barik

2017-12-01

Full Text Available In this paper, a new type of dual-frequency impedance transformer is presented for ultra-high transforming ratio. The proposed configuration consists of parallel coupled-line, series transmission lines and short-ended stubs. The even and odd-mode analysis is applied to obtain the design equations and hence to provide an accurate solution. Three examples of the dual-frequency transformer with load impedance of 500, 1000 and 1500 Ω are designed to study the matching capability and bandwidth property. To prove the frequency agility of the proposed network, three prototypes of dual-frequency impedance transformer with transforming ratio of 10, 20 and 30 are fabricated and tested. The measured return loss is greater than 15 dB at two operating frequencies for all the prototypes. Also, the bandwidth is more than 60 MHz at each frequency band for all the prototypes. The measured return loss is found in good agreement with the circuit and full-wave simulations.

A power scalable PLL frequency synthesizer for high-speed Δ—Σ ADC

International Nuclear Information System (INIS)

Han Siyang; Chi Baoyong; Zhang Xinwang; Wang Zhihua

2014-01-01

A 35–130 MHz/300–360 MHz phase-locked loop frequency synthesizer for Δ—Σ analog-to-digital converter (ADC) in 65 nm CMOS is presented. The frequency synthesizer can work in low phase-noise mode (300–360 MHz) or in low-power mode (35–130 MHz) to satisfy the ADC's requirements. To switch between these two modes, a high frequency GHz LC VCO followed by a divided-by-four frequency divider and a low frequency ring VCO followed by a divided-by-two frequency divider are integrated on-chip. The measured results show that the frequency synthesizer achieves a phase-noise of −132 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 1.12 ps with 1.74 mW power consumption from a 1.2 V power supply in low phase-noise mode. In low-power mode, the frequency synthesizer achieves a phase-noise of −112 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 7.23 ps with 0.92 mW power consumption from a 1.2 V power supply. (semiconductor integrated circuits)

47 CFR 95.1101 - Scope.

Science.gov (United States)

2010-10-01

... SERVICES Wireless Medical Telemetry Service (WMTS) General Provisions § 95.1101 Scope. This subpart sets out the regulations governing the operation of Wireless Medical Telemetry Devices in the 608-614 MHz, 1395-1400 MHz, and 1427-1432 MHz frequency bands. See § 95.630 regarding permissible frequencies. [75...

Performance Analysis of Trench Power MOSFETs in High-Frequency Synchronous Buck Converter Applications

Directory of Open Access Journals (Sweden)

Yali Xiong

2008-01-01

Full Text Available This paper investigates the performance perspectives and theoretical limitations of trench power MOSFETs in synchronous rectifier buck converters operating in the MHz frequency range. Several trench MOSFET technologies are studied using a mixed-mode device/circuit modeling approach. Individual power loss contributions from the control and synchronous MOSFETs, and their dependence on switching frequency between 500 kHz and 5 MHz are discussed in detail. It is observed that the conduction loss contribution decreases from 40% to 4% while the switching loss contribution increases from 60% to 96% as the switching frequency increases from 500 KHz to 5 MHz. Beyond 1 MHz frequency there is no obvious benefit to increase the die size of either SyncFET or CtrlFET. The RDS(ON×QG figure of merit (FOM still correlates well to the overall converter efficiency in the MHz frequency range. The efficiency of the hard switching buck topology is limited to 80% at 2 MHz and 65% at 5 MHz even with the most advanced trench MOSFET technologies.

A Dual-Band Multiple Input Multiple Output Frequency Agile Antenna for GPSL1/Wi-Fi/WLAN2400/LTE Applications

Directory of Open Access Journals (Sweden)

Sajid Aqeel

2016-01-01

Full Text Available A novel dual-band, single element multiple input multiple output (MIMO dielectric resonator antenna (DRA with a modest frequency tuning ability is presented in this communication. The proposed antenna operates at GPS L1/Bluetooth/Wi-Fi/LTE2500/WLAN2400 frequency bands. A single dielectric resonator element is fed by two coaxial probes to excite the orthogonal modes. A couple of slots are introduced on the ground plane to improve the isolation between antenna ports. The slots also serve the purpose of reconfiguration in the lower band on placement of switches at optimized locations. The measured impedance bandwidth is 5.16% (1.41–1.49 GHz in the lower band and 26% (2.2–2.85 GHz in the higher band. The lower band reconfigures with an impedance bandwidth of 6.5% (1.55–1.65 GHz when PIN diodes are switched ON. The gain, efficiency, correlation coefficient, and diversity gain of the MIMO DRA are presented with a close agreement between simulated and measured results.

The Noisiness of Low-Frequency One-Third Octave Bands of Noise. M.S. Thesis - Southampton Univ.

Science.gov (United States)

Lawton, B. W.

1975-01-01

This study examined the relative noisiness of low frequency one-third octave bands of noise bounded by the bands centered at 25 Hz and 200 Hz, with intensities ranging from 50 db sound pressure level (SPL) to 95 db SPL. The thirty-two subjects used a method-of-adjustment technique, producing comparison-band intensities as noisy as standard bands centered at 100 Hz and 200 Hz with intensities of 60 db SPL and 72 db SPL. Four contours of equal noisiness were developed for one-third octave bands, extending down to 25 Hz and ranging in intensity from approximately 58 db SPL to 86 db SPL. These curves were compared with the contours of equal noisiness of Kryter and Pearsons. In the region of overlap (between 50 Hz and 200 Hz) the agreement was good.

Accurate frequency measurements on gyrotrons using a ''gyro-radiometer''

International Nuclear Information System (INIS)

Rebuffi, L.

1986-08-01

Using an heterodyne system, called ''Gyro-radiometer'', accurated frequency measurements have been carried out on VARIAN 60 GHz gyrotrons. Changing the principal tuning parameters of a gyrotron, we have detected frequency variations up to 100 MHz, ∼ 40 MHz frequency jumps and smaller jumps (∼ 10 MHz) when mismatches in the transmission line were present. FWHM bandwidth of 300 KHz, parasitic frequencies and frequency drift during 100 msec pulses have also been observed. An efficient method to find a stable-, high power-, long pulse-working point of a gyrotron loaded by a transmission line, has been derived. In general, for any power value it is possible to find stable working conditions tuning the principal parameters of the tube in correspondance of a maximum of the emitted frequency

Multiharmonic Frequency-Chirped Transducers for Surface-Acoustic-Wave Optomechanics

Science.gov (United States)

Weiß, Matthias; Hörner, Andreas L.; Zallo, Eugenio; Atkinson, Paola; Rastelli, Armando; Schmidt, Oliver G.; Wixforth, Achim; Krenner, Hubert J.

2018-01-01

Wide-passband interdigital transducers are employed to establish a stable phase lock between a train of laser pulses emitted by a mode-locked laser and a surface acoustic wave generated electrically by the transducer. The transducer design is based on a multiharmonic split-finger architecture for the excitation of a fundamental surface acoustic wave and a discrete number of its overtones. Simply by introducing a variation of the transducer's periodicity p , a frequency chirp is added. This combination results in wide frequency bands for each harmonic. The transducer's conversion efficiency from the electrical to the acoustic domain is characterized optomechanically using single quantum dots acting as nanoscale pressure sensors. The ability to generate surface acoustic waves over a wide band of frequencies enables advanced acousto-optic spectroscopy using mode-locked lasers with fixed repetition rate. Stable phase locking between the electrically generated acoustic wave and the train of laser pulses is confirmed by performing stroboscopic spectroscopy on a single quantum dot at a frequency of 320 MHz. Finally, the dynamic spectral modulation of the quantum dot is directly monitored in the time domain combining stable phase-locked optical excitation and time-correlated single-photon counting. The demonstrated scheme will be particularly useful for the experimental implementation of surface-acoustic-wave-driven quantum gates of optically addressable qubits or collective quantum states or for multicomponent Fourier synthesis of tailored nanomechanical waveforms.

Dual-etalon, cavity-ring-down, frequency comb spectroscopy.

Energy Technology Data Exchange (ETDEWEB)

Strecker, Kevin E.; Chandler, David W.

2010-10-01

The 'dual etalon frequency comb spectrometer' is a novel low cost spectometer with limited moving parts. A broad band light source (pulsed laser, LED, lamp ...) is split into two beam paths. One travels through an etalon and a sample gas, while the second arm is just an etalon cavity, and the two beams are recombined onto a single detector. If the free spectral ranges (FSR) of the two cavities are not identical, the intensity pattern at the detector with consist of a series of heterodyne frequencies. Each mode out of the sample arm etalon with have a unique frequency in RF (radio-frequency) range, where modern electronics can easily record the signals. By monitoring these RF beat frequencies we can then determine when an optical frequencies is absorbed. The resolution is set by the FSR of the cavity, typically 10 MHz, with a bandwidth up to 100s of cm{sup -1}. In this report, the new spectrometer is described in detail and demonstration experiments on Iodine absorption are carried out. Further we discuss powerful potential next generation steps to developing this into a point sensor for monitoring combustion by-products, environmental pollutants, and warfare agents.