Sample records for radio frequency transmitter

  1. Micro-miniature radio frequency transmitter for communication and tracking applications

    SciTech Connect

    Crutcher, R.I.; Emery, M.S.; Falter, K.G.; Nowlin, C.H. [Oak Ridge National Lab., TN (United States); Rochelle, J.M.; Clonts, L.G. [Univ. of Tennessee, Knoxville, TN (United States). Electrical Engineering Dept.

    1996-12-31

    A micro-miniature radio frequency (rf) transmitter has been developed and demonstrated by the Oak Ridge National Laboratory. The objective of the rf transmitter development was to maximize the transmission distance while drastically shrinking the overall transmitter size, including antenna. Based on analysis and testing, an application-specific integrated circuit (ASIC) with a 16-GHz gallium arsenide (GaAs) oscillator and integrated on-chip antenna was designed and fabricated using microwave monolithic integrated circuit (MMIC) technology. Details of the development and the results of various field tests will be discussed. The rf transmitter is applicable to covert surveillance and tracking scenarios due to its small size of 2.2 x 2.2 mm, including the antenna. Additionally, the 16-GHz frequency is well above the operational range of consumer-grade radio scanners, providing a degree of protection from unauthorized interception. Variations of the transmitter design have been demonstrated for tracking and tagging beacons, transmission of digital data, and transmission of real-time analog video from a surveillance camera. Preliminary laboratory measurements indicate adaptability to direct-sequence spread-spectrum transmission, providing a low probability of intercept and/or detection. Concepts related to law enforcement applications will be presented.

  2. Geophysical cave detection with a portable Very Low Frequency (VLF) radio transmitter

    NASA Astrophysics Data System (ADS)

    Bosch, Frank P.; Gurk, Marcus; Jeannin, Pierre-Yves; Müller, Imre

    2010-05-01

    In the past few years several attempts have been made to delineate karstic features as caves with geophysical methods from the surface. Knowledge about the exact position of caves might be of interest for karst hydrogeology, hazard estimation or even touristy purposes. However, interpretation of data from indirect approaches as geophysics naturally always holds a certain degree of ambiguity. A geophysical field experiment at the Swiss Jura Mountains is presented, which shows the possibility for precise lateral position delineation of an accessible cave at a depth varying from 10 to about 60 meters below surface in Mesozoic limestone. For this purpose, a portable Very Low Frequency radio transmitter prototype with a loop diameter of about one meter is placed along a 150 meter long profile at several positions inside the cave with vertical transmitter loop axis orientation. In order to delineate the transmitter locations from the surface, a Radio-Magnetotelluric (RMT) receiver prototype is used simply by triangulation of the zero-signal from the transmitter loop. The zero signal of the emitted EM field should coincide with the transmitter loop axis in case of an undistorted EM field. As in-situ proof, the transmitter positions additionally have been speleologically mapped. The results of the experiment show that the lateral positions found from the surface by combined application of a VLF transmitter and RMT receiver coincide extremely well with the locations speleologically mapped. At the deepest part of the cave (about 60 meters below surface) lateral deviation between EM- and speleological results is only about one meter. Therefore, this technique for instance enables positioning of drilling locations aiming on entering cave galleries.

  3. Radio frequency detection assembly and method for detecting radio frequencies

    DOEpatents

    Cown, Steven H. (Rigby, ID); Derr, Kurt Warren (Idaho Falls, ID)

    2010-03-16

    A radio frequency detection assembly is described and which includes a radio frequency detector which detects a radio frequency emission produced by a radio frequency emitter from a given location which is remote relative to the radio frequency detector; a location assembly electrically coupled with the radio frequency detector and which is operable to estimate the location of the radio frequency emitter from the radio frequency emission which has been received; and a radio frequency transmitter electrically coupled with the radio frequency detector and the location assembly, and which transmits a radio frequency signal which reports the presence of the radio frequency emitter.

  4. EFFECTS OF EXTERNAL RADIO TRANSMITTERS ON FISH

    EPA Science Inventory

    Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) were studied to determine the effects of externally attached radio transmitter tags. Perch that had been tagged with dummy radio tags were more susceptible to predation and more sensitive to environmental...

  5. Cancer Incidence near Radio and Television Transmitters in Great Britain

    Microsoft Academic Search

    Helen Dolk; Paul Elliott; Gavin Shaddick; Peter Walls; Bharat Thakrar

    1997-01-01

    A small area study of cancer incidence, 1974-1986, near 20 high power television (TV) and frequency modulation (FM) radio transmitters in Great Britain was carried out to place in context the findings of an earlier study around the Sutton Coldfield transmitter. The national database of postcoded cancer registrations was used with population and socioeconomic data from the 1981 census. Cancers

  6. TAIL-MOUNTED RADIO TRANSMITTERS FOR WATERFOWL

    Microsoft Academic Search

    JEAN-FRANCOIS GIROUX; DAVID V. BELL; STEVE PERCIVAL; RON W. SUMMERS

    We successfully tested tail-mounted radio transmitters on Pink-footed Geese (Anser brachyrhynchus), Barnacle Geese (Branta leucopsis), Brant (Branta bernicla) and Eur- asian Wigeon (Anas penelope). The range of detection of the transmitters was approximately 1 km and some birds were tracked for up to 4 mo. Movements and activity of the birds were not affected by the packages. We conclude that

  7. Using Radio Transmitter to Simulate Amplitude Scintillation on Radio Signals

    NASA Astrophysics Data System (ADS)

    Eccles, V.; Ilayian, R.

    2014-12-01

    Rapid fluctuation of radio-frequency signal phase and/or amplitude that is generated as a signal passing through the ionosphere is commonly referred to as ionospheric scintillation. Scintillation occurs as radio frequency signals pass through a field of plasma bubbles or irregularities that can lead to signal power fading, phase cycle slips, poor GPS signals and unusable information. The goal of this research is to use radio wave transmission to simulate scintillation under controlled conditions in order examine the performance of different GPS receivers and their ability to suppress the scintillation. The information gained from the VHF (Very High Frequency) transmitter would serve as a diagnostic tool to better understand the environmental conditions that are causing these irregularities. This system could then be used as a baseline design to be upgraded by NASA engineers to 1.2 GHz - 1.5 GHz for testing out the performance of different GPS receivers. The methodology of VHF testing could be translated to higher frequencies, such as CW (Continuous Wave), which could enhance our understanding of this phenomenon.

  8. Automatic frequency control for FM transmitter

    NASA Technical Reports Server (NTRS)

    Honnell, M. A. (inventor)

    1974-01-01

    An automatic frequency control circuit for an FM television transmitter is described. The frequency of the transmitter is sampled during what is termed the back porch portion of the horizontal synchronizing pulse which occurs during the retrace interval, the frequency sample compared with the frequency of a reference oscillator, and a correction applied to the frequency of the transmitter during this portion of the retrace interval.

  9. Exposure to radio-frequency electromagnetic fields from broadcast transmitters and risk of childhood cancer: a census-based cohort study.

    PubMed

    Hauri, Dimitri D; Spycher, Ben; Huss, Anke; Zimmermann, Frank; Grotzer, Michael; von der Weid, Nicolas; Spoerri, Adrian; Kuehni, Claudia E; Röösli, Martin

    2014-04-01

    We investigated the association between exposure to radio-frequency electromagnetic fields (RF-EMFs) from broadcast transmitters and childhood cancer. First, we conducted a time-to-event analysis including children under age 16 years living in Switzerland on December 5, 2000. Follow-up lasted until December 31, 2008. Second, all children living in Switzerland for some time between 1985 and 2008 were included in an incidence density cohort. RF-EMF exposure from broadcast transmitters was modeled. Based on 997 cancer cases, adjusted hazard ratios in the time-to-event analysis for the highest exposure category (>0.2 V/m) as compared with the reference category (<0.05 V/m) were 1.03 (95% confidence interval (CI): 0.74, 1.43) for all cancers, 0.55 (95% CI: 0.26, 1.19) for childhood leukemia, and 1.68 (95% CI: 0.98, 2.91) for childhood central nervous system (CNS) tumors. Results of the incidence density analysis, based on 4,246 cancer cases, were similar for all types of cancer and leukemia but did not indicate a CNS tumor risk (incidence rate ratio = 1.03, 95% CI: 0.73, 1.46). This large census-based cohort study did not suggest an association between predicted RF-EMF exposure from broadcasting and childhood leukemia. Results for CNS tumors were less consistent, but the most comprehensive analysis did not suggest an association. PMID:24651167

  10. Effects of external radio transmitters on fish

    SciTech Connect

    Ross, M.J. (Univ. of Minnesota, Minneapolis); McCormick, J.H.

    1981-04-01

    Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) were studied to determine the effects of externally attached radio transmitter tags. Perch that had been tagged with dummy radio tags were more susceptible to predation and more sensitive to environmental stress than were controls. Feeding and respiration rates were similar among dummy tagged and control groups of perch over a 6-week period. The feeding rate of dummy tagged largemouth bass was lower than that of untagged fish over a 3,5-week period. On the basis of these studies, we conclude that weights of external transmitters in water should be less than 1.5% of the fish weight. Design considerations should include streamlining components and an anterior attachment wire at the extreme leading edge of an external transmitter to prevent entanglement of the tag in surrounding vegetation.

  11. Radio frequency power load and associated method

    NASA Technical Reports Server (NTRS)

    Sims, III, William Herbert (Inventor); Chavers, Donald Gregory (Inventor); Richeson, James J. (Inventor)

    2010-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus includes a container and a fluid having an ion source therein, the fluid being contained in the container. Two conductors are immersed in the fluid. A radio frequency transmission system includes a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus includes a fluid having an ion source therein, and two conductors immersed in the fluid. A method of dissipating power generated by a radio frequency transmission system includes the steps of: immersing two conductors of a radio frequency power load apparatus in a fluid having an ion source therein; and connecting the apparatus to an amplifier of the transmission system.

  12. Radio Frequency Power Load and Associated Method

    NASA Technical Reports Server (NTRS)

    Srinivasan, V. Karthik (Inventor); Freestone, Todd M. (Inventor); Sims, William Herbert, III (Inventor)

    2014-01-01

    A radio frequency power load and associated method. A radio frequency power load apparatus may include a container with an ionized fluid therein. The apparatus may include one conductor immersed in a fluid and another conductor electrically connected to the container. A radio frequency transmission system may include a radio frequency transmitter, a radio frequency amplifier connected to the transmitter and a radio frequency power load apparatus connected to the amplifier. The apparatus may include a fluid having an ion source therein, one conductor immersed in a fluid, and another conductor electrically connected to the container. A method of dissipating power generated by a radio frequency transmission system may include constructing a waveguide with ionized fluid in a container and connecting the waveguide to an amplifier of the transmission system.

  13. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false LPRS transmitter frequencies. 95.629 Section 95.629 Telecommunication...Standards § 95.629 LPRS transmitter frequencies. (a) LPRS transmitters may operate on any frequency listed in paragraphs...

  14. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false LPRS transmitter frequencies. 95.629 Section 95.629 Telecommunication...Standards § 95.629 LPRS transmitter frequencies. (a) LPRS transmitters may operate on any frequency listed in paragraphs...

  15. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false LPRS transmitter frequencies. 95.629 Section 95.629 Telecommunication...Standards § 95.629 LPRS transmitter frequencies. (a) LPRS transmitters may operate on any frequency listed in paragraphs...

  16. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false LPRS transmitter frequencies. 95.629 Section 95.629 Telecommunication...Standards § 95.629 LPRS transmitter frequencies. (a) LPRS transmitters may operate on any frequency listed in paragraphs...

  17. 47 CFR 95.629 - LPRS transmitter frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false LPRS transmitter frequencies. 95.629 Section 95.629 Telecommunication...Standards § 95.629 LPRS transmitter frequencies. (a) LPRS transmitters may operate on any frequency listed in paragraphs...

  18. BioRadioTransmitter: A Self-Powered Wireless Glucose-Sensing System

    PubMed Central

    Hanashi, Takuya; Yamazaki, Tomohiko; Tsugawa, Wakako; Ikebukuro, Kazunori; Sode, Koji

    2011-01-01

    Background Although an enzyme fuel cell can be utilized as a glucose sensor, the output power generated is too low to power a device such as a currently available transmitter and operating system, and an external power source is required for operating an enzyme-fuel-cell-based biosensing system. We proposed a novel biosensor that we named BioCapacitor, in which a capacitor serves as a transducer. In this study, we constructed a new BioCapacitor-based system with an added radio-transmitter circuit and a miniaturized enzyme fuel cell. Methods A miniaturized direct-electron-transfer-type compartmentless enzyme fuel cell was constructed with flavin adenine dinucleotide-dependent glucose dehydrogenase complex-based anode and a bilirubin-oxidase-based cathode. For construction of a BioRadioTransmitter wireless sensing system, a capacitor, an ultra-low-voltage charge-pump-integrated circuit, and Hartley oscillator circuit were connected to the miniaturized enzyme fuel cell. A radio-receiver circuit, comprising two field-effect transistors and a coil as an antenna, was used to amplify the signal generated from the biofuel cells. Results Radio wave signals generated by the BioRadioTransmitter were received, amplified, and converted from alternate to direct current by the radio receiver. When the capacitor discharges in the presence of glucose, the BioRadioTransmitter generates a radio wave, which is monitored by a radio receiver connected wirelessly to the sensing device. Magnitude of the radio wave transmission frequency change observed at the radio receiver was correlated to glucose concentration in the fuel cells. Conclusions We constructed a stand-alone, self-powered, wireless glucose-sensing system called a BioRadioTransmitter by using a radio transmitter in which the radio wave transmission frequency changes with the glucose concentration in the fuel cell. The BioRadioTransmitter is a significant advance toward construction of an implantable continuous glucose monitor. PMID:22027294

  19. Pressure transducer with multiplexed frequency transmitter

    Microsoft Academic Search

    R. Vrba; M. Sveda; K. Marecek

    2004-01-01

    The pressure transducer for precise and reliable pressure measurement is described. Its aim was to reach better pressure ranges with lower price. The ceramic diaphragm for pressure sensing is applied and a new principle of special ASIC with multiplexed frequency transmitter for conditioning of fX and fR frequencies controlled by CX and CR sensor capacitances is exploit. Good protection against

  20. Radio frequency spectrum management

    Microsoft Academic Search

    E. J. Sujdak Jr.

    1980-01-01

    This thesis is a study of radio frequency spectrum management as practiced by agencies and departments of the Federal Government. After a brief introduction to the international agency involved in radio frequency spectrum management, the author concentrates on Federal agencies engaged in frequency management. These agencies include the National Telecommunications and Information Administration (NTIA), the Interdepartment Radio Advisory Committee (IRAC),

  1. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209...Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to...

  2. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209...Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to...

  3. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209...Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to...

  4. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209...Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to...

  5. 47 CFR 80.209 - Transmitter frequency tolerances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Transmitter frequency tolerances. 80.209 Section 80.209...Technical Standards § 80.209 Transmitter frequency tolerances. (a) The frequency tolerance requirements applicable to...

  6. Radio frequency interference mitigation in radio astronomy

    NASA Astrophysics Data System (ADS)

    Boonstra, Albert-Jan

    2005-12-01

    The next generation of radio telescopes is expected to be one to two orders of magnitude more sensitive than the current generation. Examples of such new telescopes are the Low Frequency Array (LOFAR), currently under construction in the Netherlands, and the Square Kilometer Array (SKA), currently in a concept study phase. Another trend is that technological advances in the fields of electronics and communications systems have led to a vast increase in radio communication applications and systems, and also to an increasing demand for radio spectrum. These two trends, more sensitive telescopes and a much denser spectrum use, imply that radio astronomy will become more vulnerable to interference from radio transmitters. Although protection criteria exist for radio astronomy, it becomes increasingly difficult to keep the radio astronomy frequency bands free from interference. In order to mitigate interference in radio astronomical data, filtering techniques can be used. In this thesis, modern array signal processing techniques have been applied to narrow-band multichannel interference detection and excision, and to narrow-band spatial interference filtering. By investigating the subspace structure of the telescope array output covariance matrices, new results were found, such as upper limits on interference residuals after excision and spatial filtering. The effect of bandwidth, extendedness of the interfering sources, and multipath effects on the detection and spatial filter effectiveness were studied as well. The advantage of a multichannel approach over a single telescope approach was demonstrated by using experimental data from the Westerbork Synthesis Radio Telescope (WSRT). As the performance of mitigation algorithms can be improved by calibration of the telescope gains and noise powers, calibration algorithms were developed. These algorithms were verified both for single and dual polarised arrays. Finally, a LOFAR interference mitigation strategy was developed.

  7. The Frequency Spectrum Radio.

    ERIC Educational Resources Information Center

    Howkins, John, Ed.

    1979-01-01

    This journal issue focuses on the frequency spectrum used in radio communication and on the World Administrative Radio Conference, sponsored by the International Telecommunication Union, held in Geneva, Switzerland, in the fall of 1979. Articles describe the World Administrative Radio Conference as the most important radio communication conference…

  8. Solar radio-transmitters on snail kites in Florida

    USGS Publications Warehouse

    Snyder, N.F.R.; Beissinger, S.R.; Fuller, M.R.

    1989-01-01

    The effectiveness and safety of one- and two-stage solar radio-transmitters in tracking the movements and survival of adult and fledgling Snail Kites (Rostrhamus sociabilis) were evaluated between 1979 and 1983 in southern Florida. Transmitters were attached to birds with back-pack arrangements using teflon ribbon straps. Accessory plastic shields minimized feather coverage of the solar cells. Intact transmitters were seen on birds up to 47 mo after installation. Operating lives ranged from 8 to 21 mo for one-stage, and 10 to 14 mo for two-stage transmitters. Because survival of adult and nestling radio-marked kites was high, we conclude that our transmitter-attachment method had little effect on the birds.

  9. Implanting a Radio Transmitter in a Burmese Python

    USGS Multimedia Gallery

    Researchers implant a radio transmitter in a 16-foot, 155-pound female Burmese python (Python molurus) at the South Florida Research Center, Everglades National Park. Radio-tracking builds understanding of where pythons spend their time and therefore where they can be controlled in practice. Photo c...

  10. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

    1984-01-01

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  11. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1984-12-25

    Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

  12. Radio Link Frequency Assignment

    Microsoft Academic Search

    Bertrand Cabon; Simon De Givry; Lionel Lobjois; Thomas Schiex; Joost P. Warners

    1999-01-01

    Abstract: The problem of radio frequency assignment is to provide communication channelsfrom limited spectral resources whilst keeping to a minimum the interference suered by thosewhishing to communicate in a given radio communication network. This problem is a combinatorial(NP-hard) optimization problem. In 1993, the CELAR (the French \\\\Centre d'Electronique del'Armement") built a suite of simplied versions of Radio Link Frequency Assignment

  13. Frequency agile OPO-based transmitters for multiwavelength DIAL

    SciTech Connect

    Velsko, S.P.; Ruggiero, A.; Herman, M.

    1996-09-01

    We describe a first generation mid-infrared transmitter with pulse to pulse frequency agility and both wide and narrow band capability. This transmitter was used to make multicomponent Differential Absorption LIDAR (DIAL) measurements in the field.

  14. Radio Frequency Tomography for Tunnel Detection

    Microsoft Academic Search

    Lorenzo Lo Monte; Danilo Erricolo; Francesco Soldovieri; Michael C. Wicks

    2010-01-01

    Radio frequency (RF) tomography is proposed to detect underground voids, such as tunnels or caches, over relatively wide areas of regard. The RF tomography approach requires a set of low-cost transmitters and receivers arbitrarily deployed on the surface of the ground or slightly buried. Using the principles of inverse scattering and diffraction tomography, a simplified theory for below-ground imaging is

  15. Fitting a Bird with a Tiny Radio Transmitter

    USGS Multimedia Gallery

    A captured bird is fitted with a tiny radio transmitter (designed to fall off after a few weeks) that allows it to be tracked, as well as gather data on the bird’s age, weight, fat load, wing size and shape, and general condition. ...

  16. Oviduct Insertion of Radio Transmitters as a Means of Locating Northern Pike Spawning Habitat

    Microsoft Academic Search

    Rodney B. Pierce

    2004-01-01

    I inserted radio transmitters into the oviducts of northern pike Esox lucius in an attempt to find their spawning grounds. Oviduct insertion of miniature radio transmitters was quick and easy. I hoped that transmitters would be expelled with the eggs to aid in identifying critical habitat used for egg deposition. Ten transmitters were implanted in the egg masses of female

  17. A space-frequency transmitter diversity technique for OFDM systems

    Microsoft Academic Search

    King F. Lee; Douglas B. Williams

    2000-01-01

    A transmitter diversity technique for wireless communications over frequency selective fading channels is presented. The proposed technique utilizes orthogonal frequency division multiplexing (OFDM) to transform a frequency selective fading channel into multiple flat fading subchannels on which space-frequency processing is applied. Simulation results verify that in a slow fading environment the proposed space-frequency OFDM (SF-OFDM) transmitter diversity technique has the

  18. RADIO-CONTROLLED CYBORG BEETLES: A RADIO-FREQUENCY SYSTEM FOR

    E-print Network

    Maharbiz, Michel

    RADIO-CONTROLLED CYBORG BEETLES: A RADIO-FREQUENCY SYSTEM FOR INSECT NEURAL FLIGHT CONTROL H. Sato1, University of Michigan, Ann Arbor, MI, USA ABSTRACT We present the first report of radio control of a cyborg-controlled cyborg Mecynorhina beetle; (a) live beetle platform (Mecynorhina, 4 - 10 g, 4 - 8 cm), (b) RF transmitter

  19. Influence of radio transmitters on prairie falcons (Falco mexicanus)

    USGS Publications Warehouse

    Vekasy, M.S.; Marzluff, J.M.; Kochert, Michael N.; Lehman, Robert N.; Steenhof, Karen

    1996-01-01

    We examined the effects of backpack radio transmitters on Prairie Falcon (Falco mexicanus) reproduction (percentage of occupied territories producing young and number of nestlings produced) over four years. In addition, we observed falcon aeries during brood-rearing to determine attendance at the nest and in the territory, prey delivery rates, and prey composition. We found no effect of radio tagging on Prairie Falcon productivity (nesting success and brood size) among years, although productivity varied significantly among years. The sex of the falcon tagged did not affect productivity. Radio-tagged members of pairs did not differ significantly from un-tagged members of pairs in territory attendance, nest attendance, prey delivery rates, or caching rates. Nestlings raised by radio-tagged parents attained masses similar to those reared by control parents. During low prey years, radio-tagged males brought a greater proportion of small birds and reptiles, and fewer mammals to the nest area than control males.

  20. Radio frequency identification (RFID)

    Microsoft Academic Search

    C. M. Roberts

    2006-01-01

    First conceived in 1948, Radio Frequency Identification (RFID) has taken many years for the technology to mature to the point where it is sufficiently affordable and reliable for widespread use. From Electronic Article Surveillance (EAS) for article (mainly clothing) security to more sophisticated uses, RFID is seen by some as the inevitable replacement for bar codes. With increasing use comes

  1. Architecture and Filtering Requirements for Fully Digital Multi-radio Transmitters

    E-print Network

    Paris-Sud XI, Université de

    Architecture and Filtering Requirements for Fully Digital Multi-radio Transmitters F.Robert#*1 , A- digital transmitter and identifies technical and technological challenges. Herein, we highlight trade-offs implied by such a transmitter. This work targets a flexible and low power consumption transmitter, taking

  2. Frequency stability considerations in the design of battery-powered VHF transmitters

    E-print Network

    Klughart, Kevin Mark

    1992-01-01

    : the transducer, audio frequency amplifier/filter, VHF oscillator, mixer, radio frequency (RF) amplifier, and radiating antenna structure. Each of these elements will now be briefly discussed. 1 Mixer Radiated RF (FM) AF Transducer RF Amp Antenna...-powered applications. DESIGN OBJECTIVES Given the overall view of a typical FM transmitter in Figure 1, the design goals which this document will address will center on the &equency stability of the RF oscillator section. With &equency stability as a primary goal...

  3. Design of microwave transmitters

    Microsoft Academic Search

    G. M. Utkin

    1979-01-01

    The basic aspects of the design of radio transmitters in the decimeter and centimeter wave ranges are reviewed; attention is given to both semiconductor and microwave-tube (metal-ceramic) transmitters. Engineering methods are presented for the calculation of transmitter stages, including power amplifiers, frequency multipliers, and oscillators with high frequency stability. Design examples are presented.

  4. Hematological stress indices reveal no effect of radio-transmitters on wintering Hermit Thrushes

    Microsoft Academic Search

    Andrew K. Davis; Nora E. Diggs; Robert J. Cooper; Peter P. Marra

    2008-01-01

    Radio-telemetry is often used to track birds, and several investigators have examined the possible effects of radio-transmitters on birds. One approach to this question is to determine if transmitters induce physiological stress. Using hematological indicators of stress (heterophil-lymphocyte (H\\/L) ratios), studies of captive birds have revealed no evidence that radio-transmitters cause stress. However, studies in captivity may not reflect conditions

  5. Radio Frequency Integrated Circuits

    E-print Network

    and complete transmitters. Measured results of individual circuit blocks, subsystems (e.g. VCO together Temperature Co-fired Ceramic (LTCC) packaging has been manufactured and evaluated, including a balun structure and transmitter presented in this thesis. Fifthly, thanks to my former diploma supervisor and fellow Ph.D student

  6. WIND TUNNEL EXPERIMENTS TO ASSESS THE EFFECT OFBACK-MOUNTED RADIO TRANSMITTERS ON BIRD BODY DRAG

    Microsoft Academic Search

    Holliday H. Obrecht III; C. J. Pennycuick; Mark R. Fuller

    SUMMARY The aerodynamic drag of bird bodies was measured in a wind tunnel, with and without back-mounted dummy radio transmitters. Flight performance estimates indicate that the drag of a large transmitter can cause a substantial reduction of a migrant's range, that is, the distance it can cover in non-stop flight. The drag of the transmitter can be reduced by arranging

  7. Radio frequency coaxial feedthrough

    DOEpatents

    Owens, Thomas L. (Kingston, TN)

    1989-01-17

    An improved radio frequency coaxial transmission line vacuum feed-through provided based on the use of a half-wavelength annular dielectric pressure barrier disk, or multiple disks comprising an effective half wavelength structure to eliminate reflections from the barrier surfaces. Gas-tight seals are formed about the outer and inner diameter surfaces of the barrier disk using a sealing technique which generates radial forces sufficient to form seals by forcing the conductor walls against the surfaces of the barrier disks in a manner which does not deform the radii of the inner and outer conductors, thereby preventing enhancement of the electric field at the barrier faces which limits voltage and power handling capabilities of a feedthrough.

  8. Development and Testing of a Radio Transmitter for Englacial Trilateration

    NASA Astrophysics Data System (ADS)

    Kintner, P., III; Winebrenner, D. P.; Elam, T.; Carpenter, M.

    2014-12-01

    Recent need for englacial radiolocation of instrumentation has motivated the construction of a compact radio for GPS style trilateration. The summer of 2014 offered an opportunity to test the radio across the surface of the Greenland ice sheet. A compact crystal oscillator transmitter was developed to operate on the 10 meter amateur band, to put a watt across the transmit antenna. The transmitting antenna used was a coiled dipole antenna, which was tuned in a laboratory ice block. Multiple receive antennas were constructed, a Moxon beam, and two dipole antennas one tuned for air and another tuned for ice. Transmission was tested with a constant tone while positioning the radio above and below the glacier surface. The received signal was well defined at distances of 727m along ice surface despite the complexity and water content. The performance of each receive antenna was judged on a calculated signal to noise ratio. It was theorized the gain from the Moxon beam, reported to be 10dB, would be equal to the loss of signal in the reflection on the ice-air boundary, and thus performance for the Moxon beam and the dipole in ice would be equivalent. Preliminary results suggest this to be true. Previous modeling suggested that a signal to noise ratio above ten would give satisfactory results for trilateration. Here calculated signal to noise was greater at 730m, suggesting that developing a capable receiver would be the next step towards completing englacial trilateration.

  9. Close-Up of a Radio Transmitter on an Invasive Burmese Python

    USGS Multimedia Gallery

    This close-up is of the radio-transmitter on a 16 1/2-foot python. The snake, being removed from the wild by USGS and NPS personnel, was re-captured in a thicket in Everglades National Park in April 2012. After its first capture, the snake was equipped with a radio-transmitter and an accelerometer a...

  10. Optimal location of transmitters for micro-cellular radio communication system design

    Microsoft Academic Search

    Hanif D. Sherali; Chandra Mohan Pendyala; Theodore S. Rappaport

    1996-01-01

    This paper is concerned with the mathematical modeling and analysis of a radio communication system design problem that seeks an optimal location of a single transmitter, or that of multiple transmitters, in order to serve a specified distribution of receivers. The problem is modeled by discretizing the radio coverage region into a grid of receiver locations and by specifying a

  11. Stabilized radio-frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1982-09-29

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  12. Highly Linear Single Sideband Transmitter for Radio-Over-Fiber Systems

    Microsoft Academic Search

    Ana Ferreira; Tiago Silveira; Daniel Fonseca; Rui Ribeiro; Paulo Monteiro

    2011-01-01

    A wavelength-independent single sideband (SSB) transmitter for high-performance radio-over-fiber links is pro- posed. Third order intermodulation distortion improvement of 9 dB is experimentally verified in back-to-back comparing to a conventional SSB transmitter. Simulation results demonstrate dispersion-independent performance of the proposed transmitter, while the conventional transmitter is further penalized by 8 dB. Index Terms—Modulator linearization, optical carrier sup- pressed modulation, optical

  13. Radio Frequency Identification

    NSDL National Science Digital Library

    Leske, Cavin.

    A wealth of information about RFID is available at this site (1), ranging from background material to case studies. A discussion highlighting the myriad of uses for RFID is included. Transponder News (2) offers several articles that explore the technology in greater detail. Two in particular look at current and future trends, while others are editorial essays and technical notes. Pacific Northwest National Laboratory (3) is involved in the development of advanced tags for RFID systems. The project's homepage outlines current research efforts for three different types of radio frequency tags, which are being designed for varying degrees of sophistication and functionality. While RFID technology can be very useful, the fact that information about items is collected remotely raises concerns about privacy and security. This issue is addressed in a research paper from the Massachusetts Institute of Technology (4). The authors review current RFID systems and their operation, and then propose a number of security mechanisms that could reduce the risk associated with their use. A paper presented at the 2002 European Wireless Conference (5) compares the performance of RFID systems that use ultra-high frequency (UHF) communications to those that use microwave communications. It is argued that although microwave-based devices, such as Bluetooth, are suitable for worldwide operation, systems that communicate in the UHF range have greater range and less interference. The introduction of RFID smart tags in goods is discussed in this article (6). Now that these tags are cheap enough to be attached to thousands of items, stores will be able to track goods as they are transferred from storehouses to retail shelves, thereby minimizing the possibility of loss or theft. RFID technology has found another use in the war with Iraq. An article from May 20, 2003 (7) describes wristbands embedded with an RFID chip. The status and position of a wounded soldier who is wearing such a wristband can be monitored while he or she is recovering at a medical facility. For additional updates on the development of RFID technology, RFID News (8) maintains current news about emerging standards, innovative applications, and general issues.

  14. Frequency Allocation; The Radio Spectrum.

    ERIC Educational Resources Information Center

    Federal Communications Commission, Washington, DC.

    The Federal Communications Commission (FCC) assigns segments of the radio spectrum to categories of users, and specific frequencies within each segment to individual users. Since demand for channel space exceeds supply, the process is complex. The radio spectrum can be compared to a long ruler: the portion from 10-540 kiloHertz has been set aside…

  15. Evaluation of three miniature radio transmitter attachment methods for small passerines

    USGS Publications Warehouse

    Sykes, P.W., Jr.; Carpenter, J.W.; Holzman, S.; Geissler, P.H.

    1990-01-01

    Thirty-two immature common yellowthroats were used to evaluate three methods of attaching radio transmitters to the backs of small passerines: adhesive, velcro, and harness. There were no significant differences between the three methods; however, the adhesive method of transmitter attachment to small birds was found to be the preferred technique.

  16. An experimental performance evaluation of a novel radio-transmitter identification system under diverse environmental conditions

    Microsoft Academic Search

    O. H. Tekbas; N. Serinken; O. Ureten

    2004-01-01

    In this paper, the effects of environmental conditions on a radio-transmitter identification system are investigated. Transmissions from 10 commercial VHF FM transmitters operating under varying environmental conditions are analyzed using an experimental setup. It is observed that a change in environmental conditions such as battery voltage or ambient temperature causes the feature vectors to spread over the feature space, resulting

  17. NEW HARNESS DESIGN FOR ATTACHMENT OF RADIO TRANSMITTERS TO SMALL PASSERINES

    Microsoft Academic Search

    JOHN H. RAPPOLE

    Proper attachment of radio transmitters to small passerines is critical to success of telemetry studies. Neck loop and wing loop harnesses pose a number of problems. Gluing techniques are better, but are time consuming. A figure-8 harness that slides on over the legs of the bird, with the transmitter resting over the synsacrum, provides a rapid attachment technique that minimizes

  18. Effect of relative volume on radio transmitter expulsion in subadult common carp

    USGS Publications Warehouse

    Penne, C.R.; Ahrens, N.L.; Summerfelt, R.C.; Pierce, C.L.

    2007-01-01

    Expulsion of surgically implanted radio transmitters is a problem in some fish telemetry studies. We conducted a 109-d experiment to test the hypothesis that variation in relative volume of transmitters surgically implanted in subadult common carp Cyprinus carpio would affect transmitter expulsion. We also necropsied fish at the end of the experiment to evaluate histological evidence for the mechanism of expulsion. Survival rate was high during our experiment; all control fish and 88% of the fish subjected to the implantation surgery survived. Expulsion rate was low; of the 23 fish that received transmitters and survived the experiment, only two (9%) expelled the transmitters. One of these expulsions occurred through a rupture of the incision and the other occurred via the intestine. Retained transmitters were all encapsulated by tissue, and most exhibited multiple adhesions to the intestine, gonads, and body wall. Adhesions were more numerous in fish that received larger transmitters. ?? Copyright by the American Fisheries Society 2007.

  19. Radio tagging American mink ( Mustela vison )—experience with collar and intraperitoneal-implanted transmitters

    Microsoft Academic Search

    Jana Zschille; Norman Stier; Mechthild Roth

    2008-01-01

    American minks (Mustela vison) are difficult to radio tag because of their similar head and neck circumference as well as their semi-aquatic and frequently\\u000a subterranean behaviour patterns. During a radio-telemetry study of American mink, we compared collar transmitters and intraperitoneal-implanted\\u000a transmitters with reference to animal welfare and practicability in the field. Between October 2003 and March 2004, we fitted\\u000a eight

  20. Inflammatory Reaction to Fabric Collars From Percutaneous Antennas Attached to Intracoelomic Radio Transmitters Implanted in Harlequin Ducks (Histrionicus histrionicus)

    Microsoft Academic Search

    Daniel M. Mulcahy; K. A. Burek; Daniel Esler

    2007-01-01

    In wild birds implanted intracoelomically with radio transmitters, a synthetic fabric collar placed around the base of a percutaneous antenna is believed to function as a barrier to contamination of the coelom. We examined 13 fabric collars recovered from percutaneous antennas of radio transmitters implanted intracoelomically in harlequi nd ucks ( Histrionicus histrionicus) 12 months earlier. Both the transmitters and

  1. A Harness for Attaching Radio Transmitters to Large Owls Author(s): Thomas H. Nicholls and Dwain W. Warner

    E-print Network

    Minnesota, University of

    A Harness for Attaching Radio Transmitters to Large Owls Author(s): Thomas H. Nicholls and Dwain W TRANSMITTERS TO LARGE OWLS By THOMASH. NICHOLLSANDDWAINW. WARNER INTRODUCTION Owls seldom receive intensive this, miniature radio transmitters were placed successfully on Barred Owls (Strix varia) and Great

  2. THE 42m ELECTRO-OPTIC MODULATOR AS A FREQUENCY TRANSMITTER AND AS A FREQUENCY DOUBLERê

    Microsoft Academic Search

    V. MANEA; M. MOGÎLDEA

    A theoretical and experimental analysis of two applications of the 42m electro- optic modulator is performed in the time and in the frequency domains. The analysis refers to the case of a harmonic electric input signal. The two applications are that of frequency transmitter, when the modulation is linear and the output signal has the same frequency as the modulating

  3. Technique for Predicting the Radio Frequency Field Strength Inside an Enclosure

    NASA Technical Reports Server (NTRS)

    Hallett, Michael P.; Reddell, Jerry P.

    1997-01-01

    This technical memo represents a simple analytical technique for predicting the Radio Frequency (RF) field inside an enclosed volume in which radio frequency occurs. The technique was developed to predict the RF field strength within a launch vehicle fairing in which some payloads desire to launch with their telemetry transmitter radiating. This technique considers both the launch vehicle and the payload aspects.

  4. Radio Frequency Pulsewidth Modulation

    Microsoft Academic Search

    F. Raab

    1973-01-01

    The width of a train of square pulses can be varied to produce a modulated carrier at the pulse repetition frequency. When the pulse train is generated by switching (class D) transistors, highefficiency operation is possible. The efficiency of this type of amplifier can be significantly higher than that of conventional pulsewidth modulation amplifiers, since the switching rate is reduced.

  5. Flying radio frequency undulator

    SciTech Connect

    Kuzikov, S. V.; Vikharev, A. A. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod (Russian Federation)

    2014-07-21

    A concept for the room-temperature rf undulator, designed to produce coherent X-ray radiation by means of a relatively low-energy electron beam and pulsed mm-wavelength radiation, is proposed. The “flying” undulator is a high-power short rf pulse co-propagating together with a relativistic electron bunch in a helically corrugated waveguide. The electrons wiggle in the rf field of the ?1st spatial harmonic with the phase velocity directed in the opposite direction in respect to the bunch velocity, so that particles can irradiate high-frequency Compton's photons. A high group velocity (close to the speed of light) ensures long cooperative motion of the particles and the co-propagating rf pulse.

  6. Exposure of radio officers to radio frequency radiation on Danish merchant ships

    SciTech Connect

    Skotte, J.

    1984-12-01

    Exposure of radio officers to radio frequency radiation from telegraphy and telephony equipment on ships was investigated. Eighty-five measurements were made of 12 radio tranmitters operating in the 400 kHz to 25 MHz range (power up to 1200 W) and three VHF telephony transmitters in the 150 MHz band. Field measurments were made at positions normally occupied by radio officers approximately 1 m, 0.5 m and 0.25 m from the antenna feed lines. The distance between the radio operator and the measurement location was at least 0.5 m. The ratio of the electric and magnetic field strength squared (MF and HF transmitters) to ANSI C95.1-1982 radio frequency protection guides ranged from 0.001 to 0.26 (geometric mean 0.02) at the location of the seated radio officer's head. A minimum distance of 0.5 m between antenna feed lines and personnel is recommended. This would normally ensure an exposure below the ANSI safety levels.

  7. Design of radio-frequency powered coils for implant instruments

    Microsoft Academic Search

    Wen H. Ko; Sheau P. Liang; Cliff D. F. Fung

    1977-01-01

    Radio frequency (r.f.) has been investigated as a means of externally powering miniature and long term implant telemetry systems.\\u000a Optimum power transfer from the transmitter to the receiving coil is desired for total system efficiency. A seven step design\\u000a procedure for the transmitting and receiving coils is described based on r.f., coil diameter, coil spacing, load and the number\\u000a of

  8. METHODS OF RADIO-FREQUENCY CURRENT DRIVE

    E-print Network

    METHODS OF RADIO-FREQUENCY CURRENT DRIVE N. J. FISCH* Princeton Plasma Physics Laboratory-670 Radio-frequency waves can penetrate thermonuclear plasmas, depositing momentum and energy with great. INTRODUCTION Using radio-frequency (rf) waves to drive the toroidal current in tokamak reactors is attractive

  9. Radio frequency coaxial feedthrough device

    DOEpatents

    Owens, Thomas L. (Kingston, TN); Baity, Frederick W. (Oak Ridge, TN); Hoffman, Daniel J. (Oak Ridge, TN); Whealton, John H. (Oak Ridge, TN)

    1987-01-01

    A radio frequency coaxial vacuum feedthrough is provided which utilizes a cylindrical ceramic vacuum break formed of an alumina ceramic. The cylinder is coaxially disposed and brazed between tapered coaxial conductors to form a vacuum sealed connection between a pressurized upstream coaxial transmission line and a utilization device located within a vacuum container. The feedthrough provides 50 ohm matched impedance RF feedthrough up to about 500 MHz at power levels in the multimegawatt range.

  10. Intelligent Radio Frequency (RF) Monitoring 

    E-print Network

    Kimbrough, B.

    2010-01-01

    ? Intelligent Radio Frequency (RF) Monitoring ? 2009 Armstrong International, Inc. www.armstronginternational.com 2 ?Expect many enjoyable experiences!? David M. Armstrong Present Process Challenges ? Identifying a failure ? Procedure... $1340 $5430 Steam Loss Per Blow-Thru Trap (lb/hr) Cost Avoidance Per Blow-Thru Trap ($$$/time period) 5 ?Expect many enjoyable experiences!? David M. Armstrong Location 6 ?Expect many enjoyable experiences!? David M. Armstrong Continuous RF...

  11. Superconducting Radio-Frequency Cavities

    NASA Astrophysics Data System (ADS)

    Padamsee, Hasan S.

    2014-10-01

    Superconducting cavities have been operating routinely in a variety of accelerators with a range of demanding applications. With the success of completed projects, niobium cavities have become an enabling technology, offering upgrade paths for existing facilities and pushing frontier accelerators for nuclear physics, high-energy physics, materials science, and the life sciences. With continued progress in basic understanding of radio-frequency superconductivity, the performance of cavities has steadily improved to approach theoretical capabilities.

  12. Low-frequency radio navigation for the Army's Mobile Automated Field Instrumentation System /MAFIS/

    NASA Technical Reports Server (NTRS)

    Wallis, D. E.

    1980-01-01

    The Jet Propulsion Laboratory is engaged in the early phases of conceptual, preliminary design, and feasibility demonstration studies leading to determination of a design and implementation of the Army's proposed Mobile Automated Field Instrumentation System (MAFIS). An overview is provided of the current design concept for an experimental radio navigation subsystem to be implemented in the field as a part of the MAFIS study effort. Objectives of MAFIS include mobility, field-ruggedness and longevity of equipment, and low acquisition and life-cycle costs. The navigation subsystem comprises a 4-station radio transmitter network, plus the navigation receivers, network monitoring receivers and communications links, and interface to the command/control 'central' for transmitter status monitoring. Attention is given to accuracy goals, radio propagation effects, transmitter arrangement, radio-frequency allocations, position initialization and lane resolution, and transmitter and receiver functions.

  13. Stabilization of Fundamental-Frequency Microwave Oscillators for Radio-Relay Systems (Panel Discussion)

    Microsoft Academic Search

    Y. Kvarna

    1978-01-01

    In radio link equipment, frequency control of the transmitter by the use of a resonant cavity has been used since the very early days of the radio link technology and many different AFC arrangements have been designed. One simple design uses a cylindrical cavity where both the two orthogonal TE 111 modes are exited. One mode is tuned slightly lower

  14. Complication associated with abdominal surgical implantation of a radio transmitter in an American badger (Taxidea taxus).

    PubMed

    Quinn, Jessica H; Gaffney, Patricia M; Gilardi, Kirsten; Murray, Michael; Jessup, David A; Johnson, Christine K

    2010-03-01

    Radio telemetry has greatly advanced the understanding of wild animal ecology. Telemetry studies must ensure that placement of transmitters does not influence the health and behavior of study animals. Here, 10 American badgers (Taxidea taxus) were implanted with beeswax-coated abdominal radio transmitters under general anesthesia and tracked for an average of 14 mo. Behavior and movements of all badgers indicated successful short-term recovery from implantation; however, three mortalities were observed between 5 mo and 15 mo after capture. Cause of death could not be determined for two badgers due to decomposition of the carcasses. A third badger that was recovered in good postmortem condition died from sepsis secondary to a transmitter-related omental torsion. This study indicates that there is some risk associated with abdominally implanted radio transmitters in badgers. Future studies involving implanted transmitters in mammals should focus on identifying safe and effective telemetry devices that do not affect the health of study animals. American badger, omental adhesion, peritoneal implant, telemetry, Taxidea taxus. PMID:20722276

  15. Battery voltage variations and radio transmitter temperatures of the small spacecraft

    NASA Astrophysics Data System (ADS)

    Shakhparonov, V. M.; Karagioz, O. V.

    2014-05-01

    Diurnal variations of the storage battery voltages as well as temperatures of the radio transmitters on board the small satellite "Universitetsky" have been revealed. Double-humped dependences have been found, related to changes of the micro satellite position relative to the Earth and the Sun and to the on-board satellite systems' operation.

  16. Topic in Depth - Radio Frequency Identification

    NSDL National Science Digital Library

    Radio frequency identification (RFID) technology allows nearly anything to be tracked without human intervention, using transceiver tags and an electronic reader with radio communication. It is often used in inventory management, theft prevention, and vehicle identification.

  17. Demonstration of Space Optical Transmitter Development for Multiple High Frequency Bands

    NASA Technical Reports Server (NTRS)

    Nguyen, Hung; Simons, Rainee; Wintucky, Edwin; Freeman, Jon

    2013-01-01

    As the demand for multiple radio frequency carrier bands continues to grow in space communication systems, the design of a cost-effective compact optical transmitter that is capable of transmitting selective multiple RF bands is of great interest, particularly for NASA Space Communications Network Programs. This paper presents experimental results that demonstrate the feasibility of a concept based on an optical wavelength division multiplexing (WDM) technique that enables multiple microwave bands with different modulation formats and bandwidths to be combined and transmitted all in one unit, resulting in many benefits to space communication systems including reduced size, weight and complexity with corresponding savings in cost. Experimental results will be presented including the individual received RF signal power spectra for the L, C, X, Ku, Ka, and Q frequency bands, and measurements of the phase noise associated with each RF frequency. Also to be presented is a swept RF frequency power spectrum showing simultaneous multiple RF frequency bands transmission. The RF frequency bands in this experiment are among those most commonly used in NASA space environment communications.

  18. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, S.

    1984-02-09

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  19. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, Salvatore (Port Jefferson, NY)

    1985-01-01

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  20. Simulation of a Multi-band Class E PA with a PWM Envelope-coded Signal, for a Multi-radio Transmitter

    E-print Network

    Paris-Sud XI, Université de

    -radio Transmitter A. Diet1 , M. Suarez-Peñaloza2 , F. Robert3,2 , M. Villegas2 , G. Baudoin2 Abstract ­ This paper Power Ratio (PAPR) signals in the context of a multi-radio transmitter design. Solutions are currently/polar linearization, class E RF PA. I. Multi-radio Transmitter Design Wireless communications are widely used for our

  1. A space-time coded transmitter diversity technique for frequency selective fading channels

    Microsoft Academic Search

    King F. Lee; Douglas B. Williams

    2000-01-01

    A simple space-time coded orthogonal frequency division multiplexing (OFDM) transmitter diversity technique for wireless communications over frequency selective fading channels is presented. The proposed technique utilizes OFDM to transform frequency selective fading channels into multiple flat fading subchannels on which space-time coding is applied. A two-branch transmitter diversity system is implemented without bandwidth expansion and with a small increase in

  2. Array analysis of electromagnetic radiation from radio transmitters for submarine communication

    NASA Astrophysics Data System (ADS)

    Füllekrug, Martin; Mezentsev, Andrew; Watson, Robert; Gaffet, Stéphane; Astin, Ivan; Evans, Adrian

    2014-12-01

    The array analyses used for seismic and infrasound research are adapted and applied here to the electromagnetic radiation from radio transmitters for submarine communication. It is found that the array analysis enables a determination of the slowness and the arrival azimuth of the wave number vectors associated with the electromagnetic radiation. The array analysis is applied to measurements of ˜20-24 kHz radio waves from transmitters for submarine communication with an array of 10 radio receivers distributed over an area of ˜1 km ×1 km. The observed slowness of the observed wave number vectors range from ˜2.7 ns/m to ˜4.1 ns/m, and the deviations between the expected arrival azimuths and the observed arrival azimuths range from ˜-9.7° to ˜14.5°. The experimental results suggest that it is possible to determine the locations of radio sources from transient luminous events above thunderclouds with an array of radio receivers toward detailed investigations of the electromagnetic radiation from sprites.

  3. A 2.5 Gpulse/s, 25 pJ/pulse, CMOS Impulse Radio UWB Transmitter Based on

    E-print Network

    Wu, Hui

    important for battery-powered IR-UWB systems such as wireless sensor networks. Currently, pulse generationA 2.5 Gpulse/s, 25 pJ/pulse, ¢¡¤£¦¥¨§© CMOS Impulse Radio UWB Transmitter Based on Dual transmitter based on a newly-developed ultrafast pulse circuit technique, distributed waveform generator (DWG

  4. Spotforming with an array of ultra-wideband radio transmitters

    SciTech Connect

    Dowla, F; Spiridon, A

    2004-02-05

    Ultra-wideband (UWB) array signal processing has the distinct advantage in that it is possible to illuminate or focus on ''spots'' at distant points in space, as opposed to just illuminating or steering at certain directions for narrowband array processing. The term ''spotforming'' is used to emphasize the property that point-focusing techniques with UWB waveforms can be viewed as a generalization of the well-known narrowband beamforming techniques. Because methods in spotforming can lead to powerful applications for UWB systems, in this paper we derive, simulate and experimentally verify UWB spot size as a function of frequency, bandwidth and array aperture.

  5. Quench Localization in Superconducting Radio-frequency (SRF) Cavities

    E-print Network

    Baltisberger, Jay H.

    Quench Localization in Superconducting Radio-frequency (SRF) Cavities Ramesh Adhikari Lee Teng distance. Solution - Superconduting Radio-Frequency Cavities Ramesh Adhikari Quench Localization in SRF Cavities #12;Superconducting Radio-frequency Cavity (SRF) Accelerating structures for next generation

  6. INVERSION ALGORITHM FOR ESTIMATING RADIO FREQUENCY INTERFERENCE CHARACTERISTICS BASED ON

    E-print Network

    Ruf, Christopher

    INVERSION ALGORITHM FOR ESTIMATING RADIO FREQUENCY INTERFERENCE CHARACTERISTICS BASED ON KURTOSIS to recover power and duty-cycle of incoming Radio Frequency Interference (RFI) signals from kurtosis using experimental data. Index terms ­ Microwave radiometry, radio frequency interference, Simulated

  7. A 3.0 V 2 GHz transmitter IC for digital radio communication with integrated VCOs

    Microsoft Academic Search

    S. Heinen; S. Beyer; J. Fenk

    1995-01-01

    The digital European cordless telecommunication (DECT) standard applies to business as well as to the consumer market. Therefore cost effective solutions are required that are able to operate directly from a 3-cell power supply. A transmitter for digital data transmission is realized on a 7.5 GHz bipolar process. The IC, together with a CMOS PLL, constitutes the complete frequency synthesizer.

  8. Frequency monitoring a LIDAR transmitter for pulse-by-pulse analysis and control

    NASA Technical Reports Server (NTRS)

    Esproles, Carlos

    1992-01-01

    An electronic technique is described whereby the heterodyne mixing frequency of a pulsed LIDAR transmitter is displayed on a color-coded linear bar graph. The technique is of great utility for manually fine tuning the laser output frequency when the use of conventional frequency counters and spectrum analyzers is impractical in a rapidly firing system.

  9. Wind tunnel experiments to assess the effect of back-mounted radio transmitters on bird body drag

    USGS Publications Warehouse

    Obrecht, H.H., III; Pennycuick, C.J.; Fuller, M.R.

    1988-01-01

    The aerodynamic drag of bird bodies was measured in a wind tunnel, with and without back-mounted dummy radio transmitters. Flight performance estimates indicate that the drag of a large transmitter can cause a substantial reduction of a migrant's range, that is, the distance it can cover in non-stop flight. The drag of the transmitter can be reduced by arranging the components in an elongated shape, so minimizing the frontal area. The addition of a rounded fairing to the front end, and a pointed fairing behind, was found to reduce the drag of the transmitter by about onethird, as compared with an unfaired rectangular box.

  10. High power radio frequency attenuation device

    DOEpatents

    Kerns, Quentin A. (Bloomingdale, IL); Miller, Harold W. (Winfield, IL)

    1984-01-01

    A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

  11. Radio Hazard Safety Assessment for Marine Ship Transmitters: Measurements Using a New Data Collection Method and Comparison with ICNIRP and ARPANSA Limits.

    PubMed

    Halgamuge, Malka N

    2015-01-01

    We investigated the levels of radio frequency electromagnetic fields (RF EMFs) emitted from marine ship transmitters. In this study, we recorded the radio frequency (RF) electric field (EF) levels emitted from transmitters from a marine vessel focusing on the areas normally occupied by crew members and passengers. Previous studies considered radiation hazard safety assessment for marine vessels with a limited number of transmitters, such as very high-frequency (VHF) transceivers, radar and communication transmitters. In our investigation, EF levels from seven radio transmitters were measured, including: VHF, medium frequency/high frequency (MF/HF), satellite communication (Sat-Com C), AISnavigation, radar X-band and radar S-band. Measurements were carried out in a 40 m-long, three-level ship (upper deck, bridge deck and bridge roof) at 12 different locations. We developed a new data-collection protocol and performed it under 11 different scenarios to observe and measure the radiation emissions from all of the transmitters. In total, 528 EF field measurements were collected and averaged over all three levels of the marine ship with RF transmitters: the measured electric fields were the lowest on the upper deck (0.82-0.86 V/m), the highest on the bridge roof (2.15-3.70 V/m) and in between on the bridge deck (0.47-1.15 V/m). The measured EF levels were then assessed for compliance with the occupational and general public reference levels of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) standards. The ICNIRP and the ARPANSA limits for the general public were exceeded on the bridge roof; nevertheless, the occupational limits were respected everywhere. The measured EF levels, hence, complied with the ICNIRP guidelines and the ARPANSA standards. In this paper, we provide a new data collection model for future surveys, which could be conducted with larger samples to verify our observations. Furthermore, this new method could be useful as a reference for researchers and industry professionals without direct access to the necessary equipment. PMID:25996887

  12. Radio Hazard Safety Assessment for Marine Ship Transmitters: Measurements Using a New Data Collection Method and Comparison with ICNIRP and ARPANSA Limits

    PubMed Central

    Halgamuge, Malka N.

    2015-01-01

    We investigated the levels of radio frequency electromagnetic fields (RF EMFs) emitted from marine ship transmitters. In this study, we recorded the radio frequency (RF) electric field (EF) levels emitted from transmitters from a marine vessel focusing on the areas normally occupied by crew members and passengers. Previous studies considered radiation hazard safety assessment for marine vessels with a limited number of transmitters, such as very high-frequency (VHF) transceivers, radar and communication transmitters. In our investigation, EF levels from seven radio transmitters were measured, including: VHF, medium frequency/high frequency (MF/HF), satellite communication (Sat-Com C), AISnavigation, radar X-band and radar S-band. Measurements were carried out in a 40 m-long, three-level ship (upper deck, bridge deck and bridge roof) at 12 different locations. We developed a new data-collection protocol and performed it under 11 different scenarios to observe and measure the radiation emissions from all of the transmitters. In total, 528 EF field measurements were collected and averaged over all three levels of the marine ship with RF transmitters: the measured electric fields were the lowest on the upper deck (0.82–0.86 V/m), the highest on the bridge roof (2.15–3.70 V/m) and in between on the bridge deck (0.47–1.15 V/m). The measured EF levels were then assessed for compliance with the occupational and general public reference levels of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) standards. The ICNIRP and the ARPANSA limits for the general public were exceeded on the bridge roof; nevertheless, the occupational limits were respected everywhere. The measured EF levels, hence, complied with the ICNIRP guidelines and the ARPANSA standards. In this paper, we provide a new data collection model for future surveys, which could be conducted with larger samples to verify our observations. Furthermore, this new method could be useful as a reference for researchers and industry professionals without direct access to the necessary equipment. PMID:25996887

  13. Off-hull radio frequency emissions from below-deck spaces in ships

    Microsoft Academic Search

    G. Tait; M. Slocum; D. Hilton; C. Dilay; D. Southworth

    2010-01-01

    Measurement results and model analyses are presented for off-hull RF emissions caused by intentional transmitters radiating at 2.4 GHz and 5.8 GHz in enclosed, reflective spaces typically found within ships and aircraft. These transmissions can originate from shipboard wireless local area networks, radio frequency identification (RFID) tags and readers, handheld radios, and telemetry sources. Reverberant below-deck spaces with direct access

  14. Orbiting Low Frequency Array for Radio Astronomy

    E-print Network

    Langendoen, Koen

    either orbit the moon, whilst sampling during the Earth-radio eclipse phase, or orbit the Earth-moon L2 be implemented in moon orbit with today's technology. 1 #12;Number of satellites (or antennas) 10, scalableOrbiting Low Frequency Array for Radio Astronomy Raj Thilak Rajan ASTRON, Dwingeloo, NL rajan

  15. Radio Frequency Identification : regulating information privacy protection

    E-print Network

    Laufer, Deanna (Deanna Raquel)

    2007-01-01

    As applications of Radio Frequency Identification (RFID) become more profuse, the technology itself is stirring up some controversy. Due to its potential for amassing large amounts of information about both people and ...

  16. Monitoring Radio Frequency Interference: The Quiet Skies Project

    NASA Astrophysics Data System (ADS)

    Rapp, S.; Gear, C.; Maddalena, R. J.; Heatherly, S. A.

    2004-12-01

    The Quiet Skies Project is a result of the Research Experience for Teacher (RET) program during the summer of 2004. Teachers were involved in discovering the relationship between radio frequency interference (RFI) and radio astronomy observations. S. Rapp participated in astronomy observations with the Green Bank Telescope in order to characterize RFI issues at radio observatories and worked closely with the Green Bank Interference Protection Group. This work included such tasks as mitigation of locally-generated RFI from power poles and running radiation propagation studies for transmitters within the National Radio Quiet Zone. A curriculum was created to allow high school students to participate in a research effort to determine RFI levels in their communities. The aim of the project is to promote student awareness of radio astronomy and radio frequency interference through an inquiry-based science curriculum. It is hoped that the project will go national by 2007. A prototype RFI detector was created and tested at four wavelengths; 850, 900, 1425, and 1675 MHz. High school students used a beta version of the RFI detector to explore the occurrence of RFI at their schools and in their communities. The student goals of the Quiet Skies Project are to: Measure interference levels at their schools and in their communities; Reduce and transmit their data to an NRAO data base; Use online spectrum allocation data, and local information to determine possible causes of interference in their area; Analyze the complex trade-offs between radio astronomy's need for quiet skies, and other commercial, and non-commercial uses of the spectrum and share their insights with others. This work was funded by the NSF-RET program and a grant from the NASA-IDEAS program

  17. Algorithms for the radio link frequency assignment problem

    E-print Network

    Utrecht, Universiteit

    Algorithms for the radio link frequency assignment problem Karen Aardal Utrecht University Cor The radio link frequency assignment problem occurs when a network of radio links has to be established. Each. The radio link frequency assignment problem occurs when a network of radio links has to be established. Each

  18. 47 CFR 80.927 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Antenna radio frequency indicator. 80.927 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

  19. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Antenna radio frequency indicator. 80.1019 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

  20. 47 CFR 80.927 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Antenna radio frequency indicator. 80.927 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

  1. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Antenna radio frequency indicator. 80.1019 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

  2. 47 CFR 80.927 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Antenna radio frequency indicator. 80.927 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

  3. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Antenna radio frequency indicator. 80.1019 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

  4. 47 CFR 80.927 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Antenna radio frequency indicator. 80.927 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

  5. 47 CFR 80.927 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Antenna radio frequency indicator. 80.927 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

  6. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Antenna radio frequency indicator. 80.1019 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

  7. 47 CFR 80.1019 - Antenna radio frequency indicator.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Antenna radio frequency indicator. 80.1019 Section...CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

  8. Geolocation of frequency-hopping transmitters via satellite

    Microsoft Academic Search

    Alexander Sonnenschein; Warren K. Hutchinson

    1990-01-01

    An emitter-location technique which involves spaceborne interception of ground-to-satellite communication links is analyzed. In this scheme a number of interceptor satellites transpond the frequency band of interest to a terrestrial location for processing. The basic technique can be used on a variety of signal types: fixed-frequency, frequency-hopped, and pseudo-noise. The theoretical feasibility of geolocating terminals that are hopping in frequency

  9. Frequency-selective I\\/Q imbalance compensation for OFDM transmitters using online frequency-domain adaptive predistortion

    Microsoft Academic Search

    R. Keith McPherson

    2011-01-01

    I\\/Q imbalance in practical direct-conversion transmitters is a major impairment in OFDM systems. The demand for transmit OFDM signals with low error vector magnitude (EVM) while using increasing bandwidths illuminate the need for robust and high performance frequency-selective I\\/Q imbalance compensation in OFDM direct-conversion transmitters. Inspired by the 2008 work of Zou, Valkama, and Renfors, this paper extends an approach

  10. Radio Propagation at Frequencies above 30 Megacycles

    Microsoft Academic Search

    K. Bullington

    1947-01-01

    Radio propagation is affected by many factors, including the frequency, distance, antenna heights, curvature of the earth, atmospheric conditions, and the presence of hills and buildings. The influence of each of these factors at frequencies above about 30 megacycles is discussed, with most of the quantitative data being presented in a series of nomograms. By means of three or four

  11. LOFAR, a new low frequency radio telescope

    Microsoft Academic Search

    Huub Röttgering

    2003-01-01

    LOFAR, the Low Frequency Array, is a large radio telescope consisting of approximately 100 soccer-field sized antenna stations spread over a region of 400 km in diameter. It will operate at frequencies from ?10 to 240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will allow for studies of a broad range of

  12. Single Frequency, Pulsed Laser Diode Transmitter for Dial Water Vapor Measurements at 935nm

    NASA Technical Reports Server (NTRS)

    Switzer, Gregg W.; Cornwell, Donald M., Jr.; Krainak, Michael A.; Abshire, James B.; Rall, Johnathan A. R.

    1998-01-01

    We report a tunable, single frequency, narrow linewidth, pulsed laser diode transmitter at 935.68nm for remote sensing of atmospheric water vapor. The transmitter consists of a CW, tunable, external cavity diode laser whose output is amplified 2OdB using a tapered diode amplifier. The output is pulsed for range resolved DIAL lidar by pulsing the drive current to the diode amplifier at 4kHz with a .5% duty cycle. The output from the transmitter is 36OnJ/pulse and is single spatial mode. It maintains a linewidth of less than 25MHz as its wavelength is tuned across the water vapor absorption line at 935.68nm. The transmitter design and its use in a water vapor measurement will be discussed.

  13. Carbon nanotube composite optoacoustic transmitters for strong and high frequency ultrasound generation.

    PubMed

    Won Baac, Hyoung; Ok, Jong G; Park, Hui Joon; Ling, Tao; Chen, Sung-Liang; Hart, A John; Guo, L Jay

    2010-12-01

    We demonstrate carbon nanotube (CNT) composite-based optoacoustic transmitters that generate strong and high frequency ultrasound. The composite consists of CNTs grown on a substrate, which are embedded in elastomeric polymer used as an acoustic transfer medium. Under pulsed laser excitation, the composite generates very strong optoacoustic pressure: 18 times stronger than a Cr film reference and five times stronger than a gold nanoparticle composite with the same polymer. This enhancement persists over a broadband frequency range of up to 120 MHz and is confirmed by calculation. We suggest the CNT-polymer composites as highly efficient optoacoustic transmitters for high resolution ultrasound imaging. PMID:21200445

  14. Carbon nanotube composite optoacoustic transmitters for strong and high frequency ultrasound generation

    NASA Astrophysics Data System (ADS)

    Won Baac, Hyoung; Ok, Jong G.; Park, Hui Joon; Ling, Tao; Chen, Sung-Liang; Hart, A. John; Guo, L. Jay

    2010-12-01

    We demonstrate carbon nanotube (CNT) composite-based optoacoustic transmitters that generate strong and high frequency ultrasound. The composite consists of CNTs grown on a substrate, which are embedded in elastomeric polymer used as an acoustic transfer medium. Under pulsed laser excitation, the composite generates very strong optoacoustic pressure: 18 times stronger than a Cr film reference and five times stronger than a gold nanoparticle composite with the same polymer. This enhancement persists over a broadband frequency range of up to 120 MHz and is confirmed by calculation. We suggest the CNT-polymer composites as highly efficient optoacoustic transmitters for high resolution ultrasound imaging.

  15. 470 G. BAUDOIN, M. VILLEGAS, M. SUAREZ, A. DIET, F. ROBERT, PERFORMANCE ANALYSIS OF MULTIRADIO TRANSMITTER ... Performance Analysis of Multiradio Transmitter

    E-print Network

    Boyer, Edmond

    TRANSMITTER ... Performance Analysis of Multiradio Transmitter with Polar or Cartesian Architectures. This paper deals with wireless multi-radio transmitter architectures operating in the frequency band of 800 surface and power consumption. Transmitter architectures using sampling techniques and baseband or PWM

  16. LOFAR, a new low frequency radio telescope

    E-print Network

    H. J. A. Rottgering

    2003-09-19

    LOFAR, the Low Frequency Array, is a large radio telescope consisting of approximately 100 soccer-field sized antenna stations spread over a region of 400 km in diameter. It will operate at frequencies from ~10 to 240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will allow for studies of a broad range of astrophysical topics, including reionisation, transient radio sources and cosmic rays, distant galaxies and AGNs. In this contribution a status rapport of the LOFAR project and an overview of the science case is presented.

  17. E4.18 Radio Frequency Electronics Copyright 2006 Dr Stepan Lucyszyn Frequency Spectrum

    E-print Network

    Papavassiliou, Christos

    E4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn Frequency Spectrum and Applications #12;E4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn #12;E4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn #12;E4.18 Radio Frequency Electronics Copyright

  18. Illumination of the plasmasphere by terrestrial very low frequency transmitters: Model validation

    Microsoft Academic Search

    M. J. Starks; R. A. Quinn; G. P. Ginet; J. M. Albert; G. S. Sales; B. W. Reinisch; P. Song

    2008-01-01

    A composite model of wave propagation from terrestrial very low frequency (VLF) transmitters has been constructed to estimate the wave normal angles and fields of whistler mode waves in the plasmasphere. The model combines a simulation of the fields in the Earth-ionosphere waveguide, ionospheric absorption estimates, and geomagnetic field and plasma density models with fully three-dimensional ray tracing that includes

  19. Carbon nanotube composite optoacoustic transmitters for strong and high frequency ultrasound generation

    Microsoft Academic Search

    Hyoung Won Baac; Jong G. Ok; Hui Joon Park; Tao Ling; Sung-Liang Chen; A. John Hart; L. Jay Guo

    2010-01-01

    We demonstrate carbon nanotube (CNT) composite-based optoacoustic transmitters that generate strong and high frequency ultrasound. The composite consists of CNTs grown on a substrate, which are embedded in elastomeric polymer used as an acoustic transfer medium. Under pulsed laser excitation, the composite generates very strong optoacoustic pressure: 18 times stronger than a Cr film reference and five times stronger than

  20. Geolocation of frequency-hopping transmitters via satellite

    Microsoft Academic Search

    A. Sonnenschein; W. K. Hutchinson; W. C. Cummings

    1993-01-01

    An analysis of satellite-communications terminal geolocation performed by means of interception of ground terminal uplink transmissions in which a number of spaceborne interceptors transpond the frequency band of interest to terrestrial location for processing is presented. Interception regions for prototypical terminals and satellites are calculated and the results are presented parametrically as a function of uplink signal-to-noise ratio (SNR). The

  1. Inflammatory reaction to fabric collars from percutaneous antennas attached to intracoelomic radio transmitters implanted in harlequin ducks (Histrionicus histrionicus)

    USGS Publications Warehouse

    Mulcahy, D.M.; Burek, K.A.; Esler, Daniel

    2007-01-01

    In wild birds implanted intracoelomically with radio transmitters, a synthetic fabric collar placed around the base of a percutaneous antenna is believed to function as a barrier to contamination of the coelom. We examined 13 fabric collars recovered from percutaneous antennas of radio transmitters implanted intracoelomically in harlequin ducks (Histrionicus histrionicus) 12 months earlier. Both the transmitters and antenna collars were encapsulated in fibrous connective tissue, with adhesions to internal organs. Histologically, bacteria were evident at the fabric-plastic interface in 8 of 10 collars examined in cross section and along the length of the collar in 3 collars examined longitudinally. Bacteria were confined within the fibrotic sheath surrounding the transmitter and the antenna collar in all birds. No evidence of chronic systemic effects secondary to implantation was present on hematologic or serum biochemical testing. These findings indicate that antenna collars do not prevent the entry of bacteria along the percutaneous antenna but may help stabilize the antenna and minimize coelomic contamination. We conclude that radio transmitters implanted into the coelom of harlequin ducks do not appear to cause significant health problems for at least 1 year after implantation. ?? 2007 by the Association of Avian Veterinarians.

  2. Inflammatory reaction to fabric collars from percutaneous antennas attached to intracoelomic radio transmitters implanted in harlequin ducks (Histrionicus histrionicus).

    PubMed

    Mulcahy, Daniel M; Burek, K A; Esler, Daniel

    2007-03-01

    In wild birds implanted intracoelomically with radio transmitters, a synthetic fabric collar placed around the base of a percutaneous antenna is believed to function as a barrier to contamination of the coelom. We examined 13 fabric collars recovered from percutaneous antennas of radio transmitters implanted intracoelomically in harlequin ducks (Histrionicus histrionicus) 12 months earlier. Both the transmitters and antenna collars were encapsulated in fibrous connective tissue, with adhesions to internal organs. Histologically, bacteria were evident at the fabric-plastic interface in 8 of 10 collars examined in cross section and along the length of the collar in 3 collars examined longitudinally. Bacteria were confined within the fibrotic sheath surrounding the transmitter and the antenna collar in all birds. No evidence of chronic systemic effects secondary to implantation was present on hematologic or serum biochemical testing. These findings indicate that antenna collars do not prevent the entry of bacteria along the percutaneous antenna but may help stabilize the antenna and minimize coelomic contamination. We conclude that radio transmitters implanted into the coelom of harlequin ducks do not appear to cause significant health problems for at least 1 year after implantation. PMID:18069168

  3. Frequency stability considerations in the design of battery-powered VHF transmitters 

    E-print Network

    Klughart, Kevin Mark

    1992-01-01

    2 Table 3 Table 4 Tableau [Y], [Z], and [d] Matrix Element Translations . . . Generic, Biasing Passive Parameter Definitions. Oscillator Frequency Variation Differential Cob Characteristics. . . . 38 . . . . . 54 . . . 74 LIST OF PROGRAMS... or large metallic structures), and (3) very low power consumption in battery-powered environments. The major focus of this document will be on the frequency stability of the transmitter oscillator section, and techniques which may be employed to achieve...

  4. Adversarial Model for Radio Frequency Identification

    Microsoft Academic Search

    G. Avoine

    2006-01-01

    Abstract Radio Frequency Identification (RFID) systems aim to identify objects in open en - vironments with neither physical nor visual contact They consist of transponders inserted into objects, of readers, and usually of a database which contains information about the objects The key point is that authorised readers must be able to identify tags without an adversary being able to

  5. Radio-Frequency and Wideband Modulation Arraying

    NASA Technical Reports Server (NTRS)

    Brockman, M. H.

    1984-01-01

    Summing network receives coherent signals from all receivers in array. Method sums narrow-band radio-frequency (RF) carrier powers and wide-band spectrum powers of array of separate antenna/receiver systems designed for phase-locked-loop or suppressed-carrier operation.

  6. MICROWAVE AND RADIO-FREQUENCY POWER APPLICATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential for agricultural applications of radio-frequency (RF) energy for the solution of various problems in agricultural production, crop handling and storage, and product preservation and conditioning has been considered for many years. With the development of economical microwave power equ...

  7. GTAG: architecture and design of miniature transmitter with position logging for radio telemetry

    NASA Astrophysics Data System (ADS)

    ?e?ucha, Šimon; Bartoni?ka, Tomáš; Jedli?ka, Petr

    2011-10-01

    The radio telemetry is a well-known technique used within zoological research to exploit the behaviour of animal species. A usage of GPS for a frequent and precise position recording gives interesting possibility for a further enhancement of this method. We present our proposal of an architecture and design concepts of telemetry transmitter with GPS module, called GTAG, that is suited for study of the Egyptian fruit bat (Rousettus aegyptiacus). The model group we study set particular constrains, especially the weight limit (9 g) and prevention of any power resources recharging technique. We discuss the aspect of physical realization and the energyconsumption issues. We have developed a reference implementation that has been already deployed during telemetry sessions and we evaluate the experience and compare the estimated performance of our device to a real data.

  8. Radio Science, Volume ???, Number , Pages 15, Radio Frequency Interference Mitigation for Detection

    E-print Network

    Ellingson, Steven W.

    Radio Science, Volume ???, Number , Pages 1­5, Radio Frequency Interference Mitigation Berkeley, Berkeley, CA 94720, USA Radio frequency interference (RFI) is a significant problem for current of reionization experiments and with multi-beam feeds on single dish telescopes. 1. Introduction Radio frequency

  9. Low Frequency Radio Astronomy with the existing and future radio telescopes

    E-print Network

    Demoulin, Pascal

    Low Frequency Radio Astronomy with the existing and future radio telescopes A.A. Konovalenko;ABSTRACT. Radio astronomical investigations at low frequencies (meter-, decameter range) are very important development of the low frequency radio astronomy. This program includes the further modernization of UTR-2

  10. Linear radio frequency power detector

    Microsoft Academic Search

    Ming-Liang Shieh; Wei-Ju Lai; Jin-Shun Li; Yen-Lung Chiang; Han-Hsin Wu; Chin-Chung Xsieh; Chih-Ho Tu; Sheng-Wen Chen; Janne-Wha Wu

    2009-01-01

    In this paper, a design for high dynamic range applicable of power detector by using successive detection logarithmic amplifier (SDLA) configuration consists of PMOS load limiting amplifier and unbalanced source-coupled pairs. This device was been fabricated by TSMC 0.18-¿m 1P6M CMOS process. The experimental results show that the dynamic range of the power detector the frequency 900-MHz is almost kept

  11. 78 FR 13893 - Certain Radio Frequency Identification (“RFID”) Products and Components Thereof; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ...Certain Radio Frequency Identification (``RFID'') Products and Components Thereof...Certain Radio Frequency Identification (``RFID'') Products and Components Thereof...certain radio frequency identification (``RFID'') products and components...

  12. SITE TECHNOLOGY CAPSULE: IITRI RADIO FREQUENCY HEATING TECHNOLOGY

    EPA Science Inventory

    Radio frequency heating (RFH) technologies use electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. Contaminants are removed from in situ soils and transfe...

  13. Analysis of resonant coupled coils in the design of radio frequency transcutaneous links

    Microsoft Academic Search

    N. de N. Donaldson; T. A. Perkins

    1983-01-01

    A theory of coupled resonant coils has been developed which makes possible the design of radio frequency transcutaneous links\\u000a of simultaneously high overall efficiency and good displacement tolerance while keeping circuitry simple (particularly in\\u000a the implanted receiver). Series-tuned transmitter coils were used, obtaining high efficiency. In the first example a stimulator\\u000a which has excellent displacement tolerance because it works at

  14. 60GHz System-on-Package Transmitter Integrating SubHarmonic Frequency Amplitude Shift-Keying Modulator

    Microsoft Academic Search

    Dong Yun Jung; Won-il Chang; Ki Chan Eun; Chul Soon Park

    2007-01-01

    This paper proposes a simple low-temperature co-fired ceramic (LTCC) integrated transmitter using sub-harmonic amplitude shift-keying modulation for 60-GHz wireless communications applications. The transmitter system-on-package (SoP) has been monolithically implemented with a six-layer LTCC block embedding a resonator, modulator, and antenna and two active circuits, including a negative resistance generator and frequency doubler on the block. The transmitter SoP integrating whole

  15. Towards Optimization of Probe Placement for Radio-Frequency Ablation

    E-print Network

    Preusser, Tobias

    Towards Optimization of Probe Placement for Radio-Frequency Ablation Inga Altrogge1 , Tim Kr¨oger1 probes in radio-frequency (RF) ablation. The model is based on a numerical computation of the probe on Cartesian or tetrahedral grids. In this work we consider the radio-frequency (RF) ablation of liver tumors

  16. Radio labeling with pre-assigned frequencies Hans L. Bodlaender

    E-print Network

    Utrecht, Universiteit

    Radio labeling with pre-assigned frequencies Hans L. Bodlaender Hajo J. Broersma Fedor V. Fomin university technical report UU-CS-2002-026 www.cs.uu.nl #12; Radio labeling with pre-assigned frequencies #3, and for solving p-RL(l) for k-colorable graphs where a k-coloring is given. Keywords: Radio labeling, frequency

  17. Miniaturized superconducting metamaterials for radio frequencies Cihan Kurter,1,a

    E-print Network

    Anlage, Steven

    Miniaturized superconducting metamaterials for radio frequencies Cihan Kurter,1,a John Abrahams,1; published online 24 June 2010 We have developed a low-loss, ultrasmall radio frequency rf metamaterial calls for com- paratively large dimensions for radio frequency rf metama- terials, since the wavelength

  18. K-BAND RADIO FREQUENCY INTERFERENCE SURVEY OF SOUTHEASTERN MICHIGAN

    E-print Network

    Ruf, Christopher

    K-BAND RADIO FREQUENCY INTERFERENCE SURVEY OF SOUTHEASTERN MICHIGAN Shannon Curry1 , Michael Ahlers University of Denmark Orsteds Plads, Bldg. 348 DK 2800 Kgs. Lyngby, DENMARK Abstract ­ The Radio frequency of Radio Frequency Interference (RFI) that can affect microwave radiometers. It consists of a combined

  19. A Framework for Radio Frequency Spectrum Measurement and Analysis

    E-print Network

    Kansas, University of

    A Framework for Radio Frequency Spectrum Measurement and Analysis V. Rory Petty ITTC-FY2008-TR frequency spectrum is utilized. The radio frequency spectrum is an important national resource that impacts allocation and the burgeoning problem of spectrum scarcity have prompted an examination of how the radio

  20. Radio frequency analog electronics based on carbon nanotube transistors

    E-print Network

    Rogers, John A.

    Radio frequency analog electronics based on carbon nanotube transistors Coskun Kocabas*, Hoon that provide power gain in the radio frequency (RF) range. Here, we describe some progress in the area of SWNT frequency band. These results, together with integration of this technology in transistor radios that use

  1. SOME UNSOLVED CHALLENGES IN RADIO-FREQUENCY HEATING AND

    E-print Network

    SOME UNSOLVED CHALLENGES IN RADIO-FREQUENCY HEATING AND CURRENT DRIVE N. J. FISCH* Princeton Plasma, 2013 doi:10.13182/FST13-682 Several unsolved challenges in radio-frequency heating and current drive in the electronic version. I. INTRODUCTION There are many methods by which radio-frequency (rf) waves drive

  2. Frequency Shift of Radio Signals in Curved Spacetimes

    E-print Network

    Frequency Shift of Radio Signals in Curved Spacetimes E. J. B. PERSSON March 20, 2002 #12;Abstract the frequency shift of a light or radio signal is only dependent on the endpoints of the trajectory traversed on the striations in the ionosphere. It has been suggested that the radio signal undergoes a frequency shift

  3. Joint Time-Frequency Spectrum Sensing for Cognitive Radio

    E-print Network

    Paris-Sud XI, Université de

    Joint Time-Frequency Spectrum Sensing for Cognitive Radio Wael Guib`ene and Aawatif Hayar EURECOM-frequency plane. Index Terms--Cognitive radio, sensing algorithm, Wigner Ville distribution , algebraic detector, joint time frequency detection. I. INTRODUCTION Cognitive Radio (CR) as introduced by Mitola [1

  4. CITY OF PRINCE GEORGE: RADIO FREQUENCY TREATMENT OF PARTIALLY

    E-print Network

    . The study results showed that radio frequency (RF) sterilization of municipal biosolids is technically#12;CITY OF PRINCE GEORGE: RADIO FREQUENCY TREATMENT OF PARTIALLY DIGESTED/DEWATERED BIOSOLIDS Vancouver, B.C. V7M 3H7 #12;S-1 CITY OF PRINCE GEORGE RADIO FREQUENCY TREATMENT OF PARTIALLY DIGESTED

  5. Review of radio frequency microelectromechanical systems technology

    Microsoft Academic Search

    S. Lucyszyn

    2004-01-01

    A review of radio frequency microelectromechanical systems (RF MEMS) technology, from the perspective of its enabling technologies (e.g. fabrication, RF micromachined components and actuation mechanisms) is presented.A unique roadmap is given that shows how enabling technologies, RF MEMS components, RF MEMS circuits and RF microsystems packaging are linked together; leading towards enhanced integrated subsystems.An overview of the associated fabrication technologies

  6. Soil vapor extraction: Radio frequency heating

    SciTech Connect

    Lowe, D.F.; Oubre, C.L.; Ward, C.H. [eds.; Daniel, D.E.; Loehr, R.C.; Webster, M.T.; Kasevich, R.S.

    2000-07-01

    One of the most widely used techniques for treating soils contaminated with volatile organic compounds, soil vapor extraction (SVE) can also be applied to semi-volatile organic compounds (SVOCs) if the soil is heated, by applying electromagnetic energy in the radio frequency (FR) range, to increase the vapor pressure of the contaminants. However, questions remain concerning its viability and cost-effectiveness. This book presents detailed scientific and engineering information that answers these questions and more.

  7. Radio frequency (RF) heated supersonic flow laboratory

    SciTech Connect

    Wantuck, P.; Watanabe, H.

    1990-01-01

    A unique supersonic flow apparatus which employs an inductively-coupled, radio frequency (RF) torch to supply high enthalpy source gas to the nozzle inlet is described. The main features of this system are the plasma tube, a cooled nozzle assembly, and a combustion/expansion chamber with a heat exchanger. A description of these components with current test data is presented. In addition, a discussion of anticipated experiments utilizing this system is included.

  8. Remote sensing of the Earth's ionosphere perturbations using very low frequency transmitters

    NASA Astrophysics Data System (ADS)

    Boudjada, Mohammed Y.; Biagi, Pier F.; Al-Haddad, Eimad; Besser, Bruno; Wolbang, Daniel; Eichelberger, Hans; Galopeau, Patrick; Schwingenschuh, Konrad

    2015-04-01

    We report on electric field measurements recorded by DEMETER/ICE experiment above very low frequency (VLF) transmitter stations. The sun-synchronous orbits of the DEMETER satellite lead us to cover an invariant latitude range between -65° and +65° in a time interval of about 40 minutes. We select three ground-based transmitter stations localised in Australia (NWC, 19.8 kHz), in Germany (DFY, 16.58 kHz) and in Japan (JP, 17.8 kHz). We analyse the complete set of data recorded from August 2004 to December 2010. We distinguish between the VLF signals observed when the satellite was on day- or night-sides of the Earth at about 22 LT and 10 LT, respectively. We characterize the reception condition of the VLF signal taking into consideration the satellite position above the transmitter stations. We find that the signal amplitude is increasing (up to a maximum) and decreasing (down to a minimum) in a time interval of about 12 days. This 'regular' reception of the VLF signal is a signature of quiet ionosphere behaviour above the transmitter stations. We discuss in our contribution about the time intervals where the VLF signals were almost not detected. The origins of the signal attenuation seem to be linked to the ionospheric perturbations due to the solar activity, the earthquake occurrences and the geomagnetic activity.

  9. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...service for which the frequency is authorized and for...Transmitters with frequency capability for the Amateur Radio Services and Military Affiliate Radio System...certificated.) (b) All frequency determining...

  10. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...service for which the frequency is authorized and for...Transmitters with frequency capability for the Amateur Radio Services and Military Affiliate Radio System...certificated.) (b) All frequency determining...

  11. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...service for which the frequency is authorized and for...Transmitters with frequency capability for the Amateur Radio Services and Military Affiliate Radio System...certificated.) (b) All frequency determining...

  12. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...service for which the frequency is authorized and for...Transmitters with frequency capability for the Amateur Radio Services and Military Affiliate Radio System...certificated.) (b) All frequency determining...

  13. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...service for which the frequency is authorized and for...Transmitters with frequency capability for the Amateur Radio Services and Military Affiliate Radio System...certificated.) (b) All frequency determining...

  14. Reduced graphene oxide coated thin aluminum film as an optoacoustic transmitter for high pressure and high frequency ultrasound generation

    NASA Astrophysics Data System (ADS)

    Hwan Lee, Seok; Park, Mi-ae; Yoh, Jack J.; Song, Hyelynn; Yun Jang, Eui; Hyup Kim, Yong; Kang, Sungchan; Seop Yoon, Yong

    2012-12-01

    We demonstrate that reduced graphene oxide (rGO) coated thin aluminum film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound previously unattainable by other techniques. The rGO layer of different thickness is deposited between a 100 nm-thick aluminum film and a glass substrate. Under a pulsed laser excitation, the transmitter generates enhanced optoacoustic pressure of 64 times the aluminum-alone transmitter. A promising optoacoustic wave generation is possible by optimizing thermoelasticity of metal film and thermal conductivity of rGO in the proposed transmitter for laser-induced ultrasound applications.

  15. Transmitter Power Control for Co-channel Interference Management in Cellular Radio Systems

    Microsoft Academic Search

    Jens Zander Radio

    1993-01-01

    Transmitter power control is a necessity to combat "near-far" problems in radiosystems using receivers with limited "dynamic range" (such as conventional DSCDMAsystems). Transmitter power control, however, can also be used tocontrol cochannel interference, i.e. interference from other users using the samechannel (code or time slot). For this purpose, it has been shown that theoptimum transmitter power configuration is found by

  16. Heating of the nighttime D region by very low frequency transmitters

    NASA Technical Reports Server (NTRS)

    Rodriguez, Juan V.; Inan, Umran S.; Bell, Timothy F.

    1994-01-01

    VLF signals propagating in the Earth-ionosphere waveguide are used to probe the heated nighttime D region over three U.S. Navy very low frequency (VLF,3-30 kHz) transmitters. Ionospheric cooling and heating are observed when a transmitter turns off and on in the course of normal operations. Heating by the 24.0-kHz NAA transmitter in Cutler, Maine, (1000 kW radiated power) was observed by this method in 41 of 52 off/on episodes during December 1992, increasing the amplitude and retarding the phase of the 21.4-kHz NSS probe wave propagating from Annapolis, Maryland, to Gander, Newfoundland, by as much as 0.84 dB and 5.3 deg, respectively. In 6 of these 41 episodes, the amplitude of the 28.5-kHz NAU probe wave propagating from Puerto Rico to Gander was also perturbed by as much as 0.29 dB. The latter observations were unexpected due to the greater than 770 km distance between NAA and the NAU-Gander great circle path. Heating by the NSS (21.4 kHz, 265 kW) and NLK (24.8 kHz, 850 kW) transmitters was observed serendipitously in data from earlier measurements of the amplitudes of VLF signals propagating in the Earth-ionosphere waveguide. A three-dimensional model of wave absorption and electron heating in a magnetized, weakly ionized plasma is used to calculate the extent nad shape of the collision frequency (i.e., electron temperature) enhancement above a VLF transmitter. The enhancements are annular, with a geomagnetic north-south asymmetry and a radius at the outer half-maximum of the collision frequency enhancement of about 150 km. Heating by the NAA transmitter is predicted to increase the nighttime D region electron temperature by as much as a factor of 3. The calculated changes in the D region conductivity are used in a three-dimensional model of propagation in the Earth-ionosphere wavelength to predict the effect of the heated patch on a subionospheric VLF probe wave. The range of predicted scattered field amplitudes is in general consistent with the observed signal perturbations. Discrepanices in the predictions are attributed to lack of knowledge of the D region electron density profile along the probe wave great circle paths.

  17. Parallel PWMs Based Fully Digital Transmitter with Wide Carrier Frequency Range

    PubMed Central

    Zhou, Bo; Zhang, Kun; Zhou, Wenbiao; Zhang, Yanjun; Liu, Dake

    2013-01-01

    The carrier-frequency (CF) and intermediate-frequency (IF) pulse-width modulators (PWMs) based on delay lines are proposed, where baseband signals are conveyed by both positions and pulse widths or densities of the carrier clock. By combining IF-PWM and precorrected CF-PWM, a fully digital transmitter with unit-delay autocalibration is implemented in 180?nm CMOS for high reconfiguration. The proposed architecture achieves wide CF range of 2?M–1?GHz, high power efficiency of 70%, and low error vector magnitude (EVM) of 3%, with spectrum purity of 20?dB optimized in comparison to the existing designs. PMID:24223503

  18. On the Carrier Frequency Offset Estimation for Frequency Hopping Burst Mode Mobile Radio

    E-print Network

    Yýlmaz, Özgür

    On the Carrier Frequency Offset Estimation for Frequency Hopping Burst Mode Mobile Radio G¨okhan M to the number of radio frequency bursts (RFB) used, constellation and SNR level, and is an important measure a message over multiple radio frequency bursts (RFB) to increase the robustness of the system against

  19. Olfar orbiting low frequency antenna for radio astronomy

    Microsoft Academic Search

    Mark Bentum; Albert Jan Boonstra

    2009-01-01

    New interesting astronomical science drivers for very low frequency radio astronomy have emerged, ranging from studies of the astronomical dark ages, the epoch of reionization, exoplanets, to ultra-high energy cosmic rays. However, astronomical observations with Earth-bound radio telescopes at very low frequencies are hampered by the ionospheric plasma, which scatters impinging celestial radio waves. This effect is larger at lower

  20. Cubesat Missions for Low Frequency Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Jones, Dayton L.

    2013-01-01

    There have been many concepts and several mission proposals for low frequency radio interferometers in space during the past two decades. Most of these idea are based on multiple small spacecraft, each acting as one antenna element in a three-dimensional array. The science goals for single cubesats or arrays operating at frequencies near and below Earth's ionosphere cutoff span a wide range research areas from solar and planetary observations to galactic and extragalactic astronomy to cosmological observations of large-scale structure evolution before the epoch of reionization. Recently several groups have realized that the rapid progress in the capabilities of cubesats make them a logical basis for such mission concepts. A workshop on cubesat-based low frequency radio astronomy missions was held at the Keck Institute for Space Studies (KISS) at Caltech during July 2012. This paper will summarize the discussions and conclusions from that workshop. These include a number of future mission ideas based on cubesat technologies, as well as recommendations for near-term technology demonstrations that would reduce risk for many of the potential missions. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Support from the JPL Center for Academic Partnerships and KISS is gratefully acknowledged.

  1. Surgical and immediate post-release mortality of harlequin ducks (Histrionicus histrionicus) implanted with abdominal radio transmitters with percutaneous antennae.

    PubMed

    Mulcahy, D M; Esler, D

    1999-09-01

    Radiotelemetry is an essential tool in the study of free-ranging bird populations, and a variety of transmitter-attachment methods have been developed. A promising new method is abdominal implantation of a transmitter with a percutaneous antenna. Researchers using this technique should be concerned about and aware of mortality during surgery and during the immediate post-release period (the 14-day period following surgery). Of 307 radio-implant surgeries performed between 1995 and 1997 in harlequin ducks (Histrionicus histrionicus), 7 (2.3%) deaths were documented during surgery or anesthetic recovery. Of 295 birds released with implanted radios, 10 (3.4%) died during the immediate post-release period. Modifications to anesthetic procedures used in the 204 surgeries performed in 1996 and 1997 reduced mortality to 1.5% during surgery and 1.5% during the immediate post-release period. Anesthetic modifications included intubation of all birds, placement of birds on an elevated platform that allowed the head to rest at a level lower than the body during surgery, placement of a heated water blanket under the birds during surgery, monitoring of body temperature, and use of electrocardiogram and Doppler ultrasound to monitor heart rates and arrhythmias. Low levels of mortality associated with abdominal implantation of radio transmitters may be unavoidable, but mortality can be minimized with adjustments to anesthetic technique. PMID:10572863

  2. Surgical and immediate postrelease mortality of harlequin ducks (Histrionicus histrionicus) implanted with abdominal radio transmitters with percutaneous antennae

    USGS Publications Warehouse

    Mulcahy, D.M.; Esler, Daniel

    1999-01-01

    Radiotelemetry is an essential tool in the study of free-ranging bird populations, and a variety of transmitter-attachment methods have been developed. A promising new method is abdominal implantation of a transmitter with a percutaneous antenna. Researchers using this technique should be concerned about and aware of mortality during surgery and during the immediate postrelease period (the 14-day period following surgery). Of 307 radio-implant surgeries performed between 1995 and 1997 in harlequin ducks (Histrionicus histrionicus), 7 (2.3%) deaths were documented during surgery or anesthetic recovery. Of 295 birds released with implanted radios, 10 (3.4%) died during the immediate postrelease period. Modifications to anesthetic procedures used in the 204 surgeries performed in 1996 and 1997 reduced mortality to 1.5% during surgery and 1.5% during the immediate postrelease period. Anesthetic modifications included intubation of all birds, placement of birds on an elevated platform that allowed the head to rest at a level lower than the body during surgery, placement of a heated water blanket under the birds during surgery, monitoring of body temperature, and use of electrocardiogram and Doppler ultrasound to monitor heart rates and arrhythmias. Low levels of mortality associated with abdominal implantation of radio transmitters may be unavoidable, but mortality can be minimized with adjustments to anesthetic technique. Copyright 1999 by American Association of Zoo Veterinarians.

  3. A 78 pW 1 [b over s] 2.4 GHz radio transmitter for near-zero-power sensing applications

    E-print Network

    Mercier, Patrick P.

    This paper presents an ultra-low-standby-power radio transmitter that was designed for applications with extreme energy storage and/or energy harvesting constraints. By utilizing aggressive power gating techniques within ...

  4. Inductive coupled radio frequency plasma bridge neutralizera)

    NASA Astrophysics Data System (ADS)

    Scholze, F.; Tartz, M.; Neumann, H.

    2008-02-01

    A 13.56MHz radio frequency plasma bridge neutralizer (rf-PBN) for ion thruster applications as well as ion beam surface processing of insulating materials is presented. The energy for the plasma excitation is inductively coupled into the plasma chamber. Because no components are located inside the plasma, the lifetime of the rf-PBN is expected to be very long. A compact tuning system adapts the input power to the plasma impedance. The electron current may be controlled over a wide range by the rf input power. An electron current of up to 1.6A has been extracted.

  5. Inductive coupled radio frequency plasma bridge neutralizer

    SciTech Connect

    Scholze, F.; Tartz, M.; Neumann, H. [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318 Leipzig (Germany)

    2008-02-15

    A 13.56 MHz radio frequency plasma bridge neutralizer (rf-PBN) for ion thruster applications as well as ion beam surface processing of insulating materials is presented. The energy for the plasma excitation is inductively coupled into the plasma chamber. Because no components are located inside the plasma, the lifetime of the rf-PBN is expected to be very long. A compact tuning system adapts the input power to the plasma impedance. The electron current may be controlled over a wide range by the rf input power. An electron current of up to 1.6 A has been extracted.

  6. High efficiency, oxidation resistant radio frequency susceptor

    DOEpatents

    Besmann, Theodore M.; Klett, James W.

    2004-10-26

    An article and method of producing an article for converting energy from one form to another having a pitch-derived graphitic foam carbon foam substrate and a single layer coating applied to all exposed surfaces wherein the coating is either silicon carbide or carbides formed from a Group IVA metal. The article is used as fully coated carbon foam susceptors that more effectively absorb radio frequency (RF) band energy and more effectively convert the RF energy into thermal band energy or sensible heat. The essentially non-permeable coatings also serve as corrosion or oxidation resistant barriers.

  7. Tracing Ghost Cavities with Low Frequency Radio Observations

    E-print Network

    Tracy Clarke; Elizabeth Blanton; Craig Sarazin; Namir Kassim; Loren Anderson; Henrique Schmitt; Gopal-Krishna; Doris Neumann

    2006-12-20

    We present X-ray and multi-frequency radio observations of the central radio sources in several X-ray cavity systems. We show that targeted radio observations are key to determining if the lobes are being actively fed by the central AGN. Low frequency observations provide a unique way to study both the lifecycle of the central radio source as well as its energy input into the ICM over several outburst episodes.

  8. Radio frequency ion source operated with field effect transistor based radio frequency system

    Microsoft Academic Search

    A. Ando; A. Komuro; T. Matsuno; K. Tsumori; Y. Takeiri

    2010-01-01

    Characteristics of radio frequency (RF) plasma production are investigated using a field effect transistor inverter power supply as an RF wave source. With the frequency of around 0.3 MHz, an electron density over 1018 m-3 is produced in argon plasma. Although lower densities are obtained in hydrogen plasma, it drastically increased up to 5×1018 m-3 with an axial magnetic field

  9. Optical generation of radio-frequency power

    NASA Astrophysics Data System (ADS)

    Hietala, V. M.; Vawter, G. A.; Brennan, T. M.; Hammons, B. E.; Meyer, W. J.

    1994-11-01

    An optical technique for high-power radio-frequency (RF) signal generation is described. The technique uses a unique photodetector based on a traveling-wave design driven by an appropriately modulated light source. The traveling-wave photodetector (TWPD) exhibits simultaneously a theoretical quantum efficiency approaching 100% and a very large electrical bandwidth. Additionally, it is capable of dissipating the high-power levels required for the RF generation technique. The modulated light source is formed by either the beating together of two lasers or by the direct modulation of a light source. A system example is given which predicts RF power levels of 100's of mW's at millimeter wave frequencies with a theoretical 'wall-plug' efficiency approaching 34%.

  10. Optical generation of radio-frequency power

    SciTech Connect

    Hietala, V.M.; Vawter, G.A.; Brennan, T.M.; Hammons, B.E.; Meyer, W.J.

    1994-11-01

    An optical technique for high-power radio-frequency (RF) signal generation is described. The technique uses a unique photodetector based on a traveling-wave design driven by an appropriately modulated light source. The traveling-wave photodetector (TWPD) exhibits simultaneously a theoretical quantum efficiency approaching 100 % and a very large electrical bandwidth. Additionally, it is capable of dissipating the high-power levels required for the RF generation technique. The modulated light source is formed by either the beating together of two lasers or by the direct modulation of a light source. A system example is given which predicts RF power levels of 100`s of mW`s at millimeter wave frequencies with a theoretical ``wall-plug`` efficiency approaching 34%.

  11. Comparison of Pulsed Sinusoid Radio Frequency Interference Detection Algorithms Using Time and

    E-print Network

    Ruf, Christopher

    Comparison of Pulsed Sinusoid Radio Frequency Interference Detection Algorithms Using Time of two major Radio Frequency Interference (RFI) detection algorithms is compared. The peak detection ­ Microwave radiometry, radio frequency interference I. INTRODUCTION xtremely pervasive levels of Radio

  12. Radio-Frequency Rectification on Membrane Bound Pores

    E-print Network

    Sujatha Ramachandran; Robert H. Blick; Daniel W. van der Weide

    2007-09-12

    We present measurements on direct radio-frequency pumping of ion channels and pores bound in bilipid membranes. We make use of newly developed microcoaxes, which allow delivering the high frequency signal in close proximity to the membrane bound proteins and ion channels. We find rectification of the radio-frequency signal, which is used to pump ions through the channels and pores.

  13. Radio Frequency Mass Gauging of Propellants

    NASA Technical Reports Server (NTRS)

    Zimmerli, Gregory A.; Vaden, Karl R.; Herlacher, Michael D.; Buchanan, David A.; VanDresar, Neil T.

    2007-01-01

    A combined experimental and computer simulation effort was conducted to measure radio frequency (RF) tank resonance modes in a dewar partially filled with liquid oxygen, and compare the measurements with numerical simulations. The goal of the effort was to demonstrate that computer simulations of a tank's electromagnetic eigenmodes can be used to accurately predict ground-based measurements, thereby providing a computational tool for predicting tank modes in a low-gravity environment. Matching the measured resonant frequencies of several tank modes with computer simulations can be used to gauge the amount of liquid in a tank, thus providing a possible method to gauge cryogenic propellant tanks in low-gravity. Using a handheld RF spectrum analyzer and a small antenna in a 46 liter capacity dewar for experimental measurements, we have verified that the four lowest transverse magnetic eigenmodes can be accurately predicted as a function of liquid oxygen fill level using computer simulations. The input to the computer simulations consisted of tank dimensions, and the dielectric constant of the fluid. Without using any adjustable parameters, the calculated and measured frequencies agree such that the liquid oxygen fill level was gauged to within 2 percent full scale uncertainty. These results demonstrate the utility of using electromagnetic simulations to form the basis of an RF mass gauging technology with the power to simulate tank resonance frequencies from arbitrary fluid configurations.

  14. Nb3Sn for Radio Frequency Cavities

    SciTech Connect

    Godeke, A.

    2006-12-18

    In this article, the suitability of Nb3Sn to improve theperformance of superconducting Radio-Frequency (RF)cavities is discussed.The use of Nb3Sn in RF cavitiesis recognized as an enabling technology toretain a veryhigh cavity quality factor (Q0) at 4.2 K and tosignificantly improve the cavity accelerating efficiency per unitlength(Eacc). This potential arises through the fundamental properties ofNb3Sn. The properties that are extensively characterized in theliterature are, however, mainly related to improvements in currentcarrying capacity (Jc) in the vortex state. Much less is available forthe Meissner state, which is of key importance to cavities. Relevantdata, available for the Meissner state is summarized, and it is shown howthis already validates the use of Nb3Sn. In addition, missing knowledgeis highlighted and suggestions are given for further Meissner statespecific research.

  15. Hybrid optical radio frequency airborne communications

    NASA Astrophysics Data System (ADS)

    Bagley, Zachary C.; Hughes, David H.; Juarez, Juan C.; Kolodzy, Paul; Martin, Todd; Northcott, Malcolm; Pike, H. Alan; Plasson, Ned D.; Stadler, Brian; Stotts, Larry B.; Young, David W.

    2012-05-01

    Optical RF Communications Adjunct Program flight test results provide validation of the theoretical models and hybrid optical radio frequency (RF) airborne system concepts developed by the Defense Advanced Research Projects Agency and the U.S. Air Force Research Laboratory. Theoretical models of the free-space optical communications (FSOC), RF, and network components accurately predict the flight test results under a wide range of day and night operating conditions. The FSOC system, including the adaptive optics and optical modem, can operate under high turbulence conditions. The RF and network mechanisms of Layer 2 retransmission and failover provide increased reliability, reducing end-to-end packet error rates. Overall the test results show that stable, long-range FSOC is possible and practical for near-term operations.

  16. Radio-frequency low-coherence interferometry.

    PubMed

    Fernández-Pousa, Carlos R; Mora, José; Maestre, Haroldo; Corral, Pablo

    2014-06-15

    A method for retrieving low-coherence interferograms, based on the use of a microwave photonics filter, is proposed and demonstrated. The method is equivalent to the double-interferometer technique, with the scanning interferometer replaced by an analog fiber-optics link and the visibility recorded as the amplitude of its radio-frequency (RF) response. As a low-coherence interferometry system, it shows a decrease of resolution induced by the fiber's third-order dispersion (?3). As a displacement sensor, it provides highly linear and slope-scalable readouts of the interferometer's optical path difference in terms of RF, even in the presence of third-order dispersion. In a proof-of-concept experiment, we demonstrate 20-?m displacement readouts using C-band EDFA sources and standard single-mode fiber. PMID:24978555

  17. An improved integrally formed radio frequency quadrupole

    DOEpatents

    Abbott, S.R.

    1987-10-05

    An improved radio frequency quadrupole is provided having an elongate housing with an elongate central axis and top, bottom and two side walls symmetrically disposed about the axis, and vanes formed integrally with the walls, the vanes each having a cross-section at right angles to the central axis which tapers inwardly toward the axis to form electrode tips spaced from each other by predetermined distances. Each of the four walls, and the vanes integral therewith, is a separate structural element having a central lengthwise plane passing through the tip of the vane, the walls having flat mounting surfaces at right angles to and parallel to the control plane, respectively, which are butted together to position the walls and vane tips relative to each other. 4 figs.

  18. Transistorized frequency reference and control system for 920 channel military vehicular VHF-FM receiver-transmitter

    Microsoft Academic Search

    F. Brauer; D. Kammer

    1958-01-01

    Receiver and transmitter frequency control is accomplished by two phase comparison loops, The primary loop compares the phase of the receiver VFO with the output of a Crystal Reference System containing a total of 13 crystals and using three stages of interpolation to cover the required frequency range. The secondary loop, on transmit, uses the controlled receiver VFO for the

  19. 47 CFR 87.195 - Frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Section 87.195 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations Emergency Locator Transmitters § 87.195 Frequencies. (a)...

  20. 47 CFR 87.195 - Frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Section 87.195 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations Emergency Locator Transmitters § 87.195 Frequencies. (a)...

  1. 47 CFR 87.195 - Frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Section 87.195 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations Emergency Locator Transmitters § 87.195 Frequencies. (a)...

  2. 47 CFR 87.195 - Frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Section 87.195 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations Emergency Locator Transmitters § 87.195 Frequencies. (a)...

  3. 47 CFR 87.195 - Frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Section 87.195 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AVIATION SERVICES Aircraft Stations Emergency Locator Transmitters § 87.195 Frequencies. (a)...

  4. Power Supplies and Radio Frequency Department at Culham

    E-print Network

    Power Supplies and Radio Frequency Department at Culham Culham Centre for Fusion Energy #12;We for plasma heating; highly regulated HV DC supplies for multi-megawatt particle accelerators and radio frequency generators. We have an ongoing need for power electrical engineers and technicians across a range

  5. PHOTONIC PROCESSING OF ULTRA-BROADBAND RADIO FREQUENCY A Dissertation

    E-print Network

    Purdue University

    PHOTONIC PROCESSING OF ULTRA-BROADBAND RADIO FREQUENCY WAVEFORMS A Dissertation Submitted Hamidi and my father Esmaeil Hamidi. #12;iii ACKNOWLEDGMENTS I would like to thank my advisor Professor......................................................................................12 2. RADIO FREQUENCY PHOTONIC MATCHED FILTER.......................................14 2.1 Hyperfine

  6. DEMONSTRATION BULLETIN: RADIO FREQUENCY HEATING - KAI TECHNOLOGIES, INC.

    EPA Science Inventory

    Radio frequency heating (RFH) is a process that uses electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. An RFH system developed by KAI Technologies, I...

  7. SITE TECHNOLOGY CAPSULE: IITRI RADIO FREQUENCY HEATING TECHNOLOGY

    EPA Science Inventory

    Radio frequency heating (RFH) technologies use electromagnetic energy in the radio frequency i(RF) band to heat soil in-situ, thereby potentially enhancing the performances of standard soil vapor extraction (SVE) technologies. ontaminants are removed from in situ soils and transf...

  8. IN SITU AND SOIL DECONTAMINATION BY RADIO FREQUENCY HEATING

    EPA Science Inventory

    In situ radio frequency heating is performed by applying electromagnetic energy in the radio frequency band to an array of electrodes placed in bore holes drilled through the contaminated soil. he process removes organic contaminants from large volumes of soil by volatilization, ...

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  10. A Hybrid Radio Frequency and Broadcast Visible Light Communication System

    E-print Network

    A Hybrid Radio Frequency and Broadcast Visible Light Communication System Michael B. Rahaim , Anna and applications. Deployed networks using Radio Frequency (RF) communications are characterized by a shared medium, limited available spectrum and limited ability to scale with increasing demand. Directional communications

  11. Ion cyclotron radio frequency systems and performance on the tandem mirror experiment-upgrade (TMX-U)

    SciTech Connect

    Moore, T.L.; Molvik, A.W.; Cummins, W.F.; Pedrotti, L.R.; Henderson, A.L.; Karsner, P.G.; Scofield, D.W.; Brooksby, C.A.

    1983-12-01

    High power ion cyclotron radio frequency (ICRF) systems are now gaining greater attention than before as prime driver ion heating systems. Lawrence Livermore National Laboratory (LLNL) has installed a 200 kW high frequency (HF) transmitter system on its Tandem Mirror Experiment-Upgrade (TMX-U). This paper describes the system, antenna, controls, and monitoring apparatus. The transmitter operates into a high Q antenna installed in the central cell region of the experiment. It incorporates a dual-port feedback system to automatically adjust the transmitter's output power and allow the maximum consistent with the plasma loading of the antenna. Special techniques have been used to measure, in real-time, the dynamically changing loading values presented by the plasma. From the measurements, the antenna impedance can be optimized for specified plasma density.

  12. Sponsored by NASA/ESTO NNG05GL97G Detection of Radio Frequency Interference

    E-print Network

    Ruf, Christopher

    of Radio Frequency Interference (RFI) with the Aquarius Radiometer. The detection algorithm identifies sources or Radio Frequency Interference (RFI) are mistakenly detected and interpreted as natural radio_________________________________________ Sponsored by NASA/ESTO NNG05GL97G Detection of Radio

  13. Frequency-Selective I\\/Q Mismatch Calibration of Wideband Direct-Conversion Transmitters

    Microsoft Academic Search

    Lauri Anttila; Mikko Valkama; Markku Renfors

    2008-01-01

    The current trend in building low-cost yet flexible radio transceivers is to use the so-called direct-conversion principle, which is based on complex (I\\/Q) up- and down conversions. Such transceivers are, however, sensitive to mismatches between the I and Q branches. These mismatches are unavoidable in any practical implementation, and result in finite attenuation of the mirror frequencies. In addition to

  14. Low Frequency Study of Rotating Radio Transients

    NASA Astrophysics Data System (ADS)

    McCrackan, Michael; Miller, Rossina B.; Stovall, Kevin; McLaughlin, Maura; Taylor, Gregory B.

    2015-01-01

    Rotating Radio Transients are a type of radio emitting pulsar, first discovered in 2006, that, while possessing similar pulse widths and pulse intensities to those of regular pulsars, differ from the pulsars observed thus far due to their exhibiting a variability in the emission of their individual pulses - the pulses of RRATs are only emitted intermittently, and individual pulses are found to be emitted on timescales ranging from a few seconds up to a few hours apart. The origin of this transient nature has yet to be determined and some suggest that pulsars may not simply shut off when they near the point that they can no longer emit, but might pulse erratically and exhibit transient behavior, making them RRATs. Alternate theories posit that the RRAT transient behavior is a geometric effect and RRATs may be fundamentally similar to nulling pulsars. Additionally, interactions with a debris field may temporarily reactivate a pulsar causing it to become a RRAT.There are nearly 100 known RRATs, and it has been predicted that the number of RRATs detected in surveys may only be a small percentage of the actual number that are present in the regions studied in those surveys. If the nature of RRATs is fundamentally similar to those of regular or nulling pulsars, the total number of radio emitting pulsars may be higher than previously predicted, and RRATs may play an important role in in our understanding of the emission mechanism of pulsars and the supernova rate of our galaxy.We present preliminary results from a survey of RRATs at 30 - 80 MHz undertaken with the first station of the Long Wavelength Array (LWA1). To date very little is known about the properties of RRATs at these low frequencies. Our study aims to determine a variety of the as yet unknown properties of RRATs, such as their pulse shapes, spectral flux densities, and spectral indices. Additional benefits will be finding more accurate values for the dispersion measures and finding timing solutions for newly discovered RRATs. Such information may help place constraints on the theories for the emission mechanisms for the RRAT transient behavior, thereby illuminating their origin and their relation to both regular and nulling pulsars.

  15. Method and apparatus for radio frequency ceramic sintering

    DOEpatents

    Hoffman, D.J.; Kimrey, H.D. Jr.

    1993-11-30

    Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents. 6 figures.

  16. Method and apparatus for radio frequency ceramic sintering

    DOEpatents

    Hoffman, Daniel J. (Oak Ridge, TN); Kimrey, Jr., Harold D. (Knoxville, TN)

    1993-01-01

    Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents.

  17. Differentially-Enhanced Sideband Imaging via Radio-frequency Encoding

    E-print Network

    Fard, A M; Jalali, B

    2015-01-01

    We present a microscope paradigm that performs differential interference imaging with high sensitivity via optical amplification and radio-frequency (RF) heterodyne detection. This method, termed differentially-enhanced sideband imaging via radio-frequency encoding (DESIRE), uniquely exploits frequency-to-space mapping technique to encode the image of an object onto the RF sidebands of an illumination beam. As a proof-of-concept, we show validation experiment by implementing radio frequency (f = 15 GHz) phase modulation in conjunction with spectrally-encoded laser scanning technique to acquire one-dimensional image of a barcode-like object using a commercial RF spectrum analyzer.

  18. Effects of radio-transmitter methods on pileated woodpeckers: an improved technique for large woodpeckers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We captured and radio-marked 64 Dryocopus pileatus (Pileated Woodpecker)in bottomland hardwood forests from February 2007 to June 2010. At least 12 (35.3%) of the first 34 birds radio-tagged died within 43 d of capture (x¯ = 8.2 d). Thus, we adjusted our radio-attachment techniques adaptively from a...

  19. Wideband micromachined microphones with radio frequency detection

    NASA Astrophysics Data System (ADS)

    Hansen, Sean Thomas

    There are many commercial, scientific, and military applications for miniature wideband acoustic sensors, including monitoring the condition or wear of equipment, collecting scientific data, and identifying and localizing military targets. The application of semiconductor micromachining techniques to sensor fabrication has the potential to transform acoustic sensing with small, reproducible, and inexpensive silicon-based microphones. However, such sensors usually suffer from limited bandwidth and from non-uniformities in their frequency response due to squeeze-film damping effects and narrow air gaps. Furthermore, they may be too fragile to be left unattended in a humid or dusty outdoor environment. Silicon microphones that incorporate capacitive micromachined ultrasonic transducer membranes overcome some of the drawbacks of conventional microphones. These micromachined membranes are small and robust enough to be vacuum-sealed, and can withstand atmospheric pressure and submersion in water. In addition, the membrane mechanical response is flat from dc up to ultrasonic frequencies, resulting in a wideband sensor for accurate spectral analysis of acoustic signals. However, a sensitive detection scheme is necessary to detect the small changes in membrane displacement that result from using smaller, stiffer membranes than do conventional microphones. We propose a radio frequency detection technique, in which the capacitive membranes are incorporated into a transmission line. Variations in membrane capacitance due to impinging sound pressure are sensed through the phase variations of a carrier signal that propagates along the line. This dissertation examines the design, fabrication, modeling, and experimental measurements of wideband micromachined microphones using sealed ultrasonic membranes and RF detection. Measurements of fabricated microphones demonstrate less than 0.5 dB variation in their output responses between 0.1 Hz to 100 kHz under electrostatic actuation of the membranes. The measured equivalent noise level of a fabricated 3 mm by 3 mm sensor is 53.8 dB(A) SPL in the audio band using a simple phase detection circuit operating at 2.8 GHz. Because the vacuum-sealed membrane structure has a low mechanical noise floor, sensitivity may be improved with higher carrier frequencies and more sophisticated detection circuitry.

  20. The effects of radio frequency radiation on the dc SQUID

    SciTech Connect

    Koch, R.H.; Foglietti, V.; Rozen, J.R.; Stawiasz, K.G.; Ketchen, M.B.; Lathrop, D.K.; Sun, J.Z.; Gallagher, W.J. [IBM Thomas J. Watson Research Center, Yorktown Heights, NY (United States)

    1994-12-31

    The effects of radio frequency radiation on the dc SQUID are examined. Simulations show how the shape of the SQUID transfer characteristic is distorted by radio frequency interference (RFI). How this affects three commonly used SQUID modulation methods is discussed, and the results explain why the authors experimentally observe the bias current reversing readout method to be the least susceptible to RFI. The commonly seen increase in the low frequency flux noise power spectrum of dc SQUIDs in unshielded environments is also explained.

  1. 76 FR 56984 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-15

    ...Regulations and Procedures for Federal Radio Frequency Management AGENCY: National...Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual...Regulations and Procedures for Federal Radio Frequency Management with which...

  2. 76 FR 18652 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-05

    ...Regulations and Procedures for Federal Radio Frequency Management AGENCY: National...Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual...Regulations and Procedures for Federal Radio Frequency Management with which...

  3. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Radio Frequency Identification (RFID) using...and Clauses 552.211-92 Radio Frequency Identification (RFID) using...insert the following clause: Radio Frequency Identification (RFID)...

  4. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Radio Frequency Identification (RFID) using...and Clauses 552.211-92 Radio Frequency Identification (RFID) using...insert the following clause: Radio Frequency Identification (RFID)...

  5. 47 CFR 2.803 - Marketing of radio frequency devices prior to equipment authorization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Marketing of radio frequency devices prior to equipment authorization...RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.803 Marketing of radio frequency devices prior to equipment...

  6. Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using the

    E-print Network

    Ruf, Christopher

    Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using-- Analysis of detectability of the kurtosis algorithm for pulsed-sinusoidal Radio Frequency Interference (RFI. Index terms ­ Microwave radiometry, radio frequency interference I. INTRODUCTION easurements made

  7. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Radio Frequency Identification (RFID) using...and Clauses 552.211-92 Radio Frequency Identification (RFID) using...insert the following clause: Radio Frequency Identification (RFID)...

  8. 75 FR 6818 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-11

    ...Regulations and Procedures for Federal Radio Frequency Management AGENCY: National...Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual...Regulations and Procedures for Federal Radio Frequency Management with which...

  9. On the Performance of Digital Adaptive Spur Cancellation for Multi-Standard Radio Frequency

    E-print Network

    On the Performance of Digital Adaptive Spur Cancellation for Multi-Standard Radio Frequency and phase noise. Keywords: Multi-standard transceiver, radio frequency impairment, spurs, digital time, radio frequency (RF) tr

  10. 77 FR 75567 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-21

    ...Regulations and Procedures for Federal Radio Frequency Management AGENCY: National...Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual...Regulations and Procedures for Federal Radio Frequency Management with which...

  11. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false Radio Frequency Identification (RFID) using passive tags. 552.211-92...211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed...clause: Radio Frequency Identification (RFID) Using Passive Tags (JAN...

  12. 78 FR 19311 - Certain Radio Frequency Identification (“RFID”) Products And Components Thereof; Institution of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ...Certain Radio Frequency Identification (``RFID'') Products And Components Thereof...certain radio frequency identification (``RFID'') products and components thereof by...certain radio frequency identification (``RFID'') products and components thereof...

  13. 48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...false Radio Frequency Identification (RFID) using passive tags. 552.211-92...211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed...clause: Radio Frequency Identification (RFID) Using Passive Tags (JAN...

  14. Assessment of gaseous CO2 and AQUI-S as anesthetics when surgically implanting radio transmitters into cutthroat trout

    USGS Publications Warehouse

    Sanderson, T.B.; Hubert, W.A.

    2007-01-01

    Tricaine methanesulfonate (MS-222) and CO2 are anesthetics that can be legally used in fisheries work in the United States, but they are limited in their field applications. A mandatory 21-d withdrawal period is required for fish exposed to MS-222. Carbon dioxide is not approved by the U.S. Food and Drug Administration, but it is a "low regulatory priority drug" that can be used legally for fish anesthesia. However, stressful induction and lengthy recovery times have been associated with CO2. AQUI-S is a clove oil derivative that has the potential to become an approved anesthetic without the limitations of MS-222 or CO2. We compared the efficacy of CO2 with that of AQUI-S when surgically implanting radio transmitters into cutthroat trout Oncorhynchus clarkii. A 20% survival rate was observed when CO2 was used in combination with silk sutures, but a 100% survival rate was observed when CO2 was used in combination with surgical staples to shorten the duration of the surgical procedure. A 100% survival rate was observed when AQUI-S was used in combination with either silk sutures or surgical staples. Carbon dioxide in combination with surgical staples seemed to provide a reasonable option when surgically implanting radio transmitters into cutthroat trout, but AQUI-S may be the preferred anesthesia because high pH and dissolved oxygen levels and low free-CO2 concentrations are maintained during surgical procedures.

  15. Detection of radio frequency interference over ocean

    NASA Astrophysics Data System (ADS)

    Tian, Xiaoxu

    The geostationary satellite television (TV) signals that are reflected off the ocean surfaces could enter the AMSR-E antenna, resulting in RFI (Radio Frequency Interference) contamination in AMSR-E 10.65 and 18.7 GHz channels. If not detected, the presence of RFI signals can result in false retrievals of oceanic environmental parameters (e.g., sea surface temperature, sea surface wind speed, rain water path) from microwave imaging radiance measurements. This study first examined the geometric relationship between the RFI source, geostationary TV satellite, and AMSR-E observation. Then a normalized Principal Component Analysis (NPCA) method is proposed and applied for RFI detection over oceans in Advanced Microwave Scanning Radiometer (AMSR)-E observations. It is found that the RFI-contaminated observations on AMSR-E descending node at 10.65 and 18.7 GHz can be successively detected near coastal areas surrounding Europe and United States continents. The results yielded from the geometric examination at another angle verify those signals detected with NPCA. The proposed NPCA algorithm is applicable in an operational environment for fast data processing and data dissemination, and is different from earlier methods, which often require a priori information.

  16. Filamentation of a Magnetized, Radio Frequency Discharge

    NASA Astrophysics Data System (ADS)

    Konopka, Uwe; Lynch, Brian; Bandyopadhyay, Pintu; Sharma, Devendra; Thomas, Edward

    2014-10-01

    A filamentation instability has been observed in a radio-frequency (rf) discharge that was subject to an externally applied, homogeneous magnetic field. The instability arises in a uniform rf-discharge after the magnetic field strength is sufficiently increased. First, the plasma shows target-like glow structures, followed by spiral structures at higher fields. Finally, the plasma breaks up into individual, string-like, magnetic field aligned filaments that seem to repel each other. A variety of filamentation states can be observed, but their overall shapes follow the aforementioned rule of magnetic field strength dependency. The detailed picture of the discharge glow, however, depends on experiment specific conditions as the geometric shape and type of the discharge electrodes, the discharge pressure and power. In an effort to verify that the observed effect is universal, we compare experimental measurements made using two different high magnetic field, dusty plasma experiment facilities: the experiment that was located at the Max Planck Institute in Garching, Germany and the newly built MDPX (magnetized dusty plasma experiment) at Auburn University, Alabama. In both experimental setups we could observe filamentation. This work is supported from funding from DOE and NSF.

  17. Radio Frequency Plasma Applications for Space Propulsion

    SciTech Connect

    Baity, F.W., Jr.; Barber, G.C.; Carter, M.D.; Chang-Diaz, F.R.; Goulding, R.H.; Ilin, A.V.; Jaeger, E.F.; Sparks, D.O.; Squire, J.P.

    1999-09-13

    Recent developments in solid-state radio frequency (RF) power technologies allow for the practical consideration of RF heated plasmas for space propulsion. These technologies permit the use of any electrical power source, de-couple the power and propellant sources, and allow for the effcient use of both the propellant mass and power. Effcient use of the propellant is obtained by expelling the rocket exhaust at the highest possible velocity, which can be orders of magnitude higher than those achieved in chemical rockets. Handling the hot plasma exhaust requires the use of magnetic nozzles, and the basic physics of ion detachment from the magnetic #12;eld is discussed. The plasma can be generated by RF using helicon waves to heat electrons. Further direct heating of the ions helps to reduce the line radiation losses, and the magnetic geometry is tailored to allow ion cyclotron resonance heating. RF #12;eld and ion trajectory calculations are presented to give a reasonably self-consistent picture of the ion acceleration process.

  18. Errors in radio-frequency quadrupole structures

    SciTech Connect

    Lysenko, W.P.

    1983-01-01

    Performance degradation caused by certain radio-frequency quadrupole (RFQ) machine errors was studied using an efficient 3-D particle-tracing simulation code for a high-brightness example. Matched beams, for which no emittance growth occurs, exist for periodic structures and were used as input beams for particle tracing in the presence of errors. We considered both slowly varying and fast (random) errors that destroy periodicity. Random dipole errors cause emittance growth because of the mismatches they introduce and also result in a motion of the beam centroid that causes a reduction in acceptance. Because of the way RFQs are manufactured, the random error amplitudes can be kept below harmful levels. More important are the slow errors, which are harmful because they reduce acceptance even though they maintain a match (up to the point of particle loss). Slow dipole errors steer the beam toward the wall, and voltage deficiencies cause instabilities in the longitudinal direction resulting in particles not being accelerated to full energy.

  19. Reduced graphene oxide coated polydimethylsiloxane film as an optoacoustic transmitter for high pressure and high frequency ultrasound generation

    NASA Astrophysics Data System (ADS)

    Lee, Seok Hwan; Lee, Yongseon; Yoh, Jack J.

    2015-02-01

    We demonstrate that reduced graphene oxide coated thin polydimethylsiloxane (rGO-PDMS) film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound, previously unattainable using other techniques. Various coatings such as rGO-Aluminum, rGO-PDMS, PDMS-alone, and aluminum-alone are deposited on the glass substrate. Under a pulsed laser excitation, rGO-PDMS transmitter generated remarkable optoacoustic pressure which is 76 times stronger than Al-alone, 5 times stronger than PDMS-alone, and 2.2 times stronger than rGO-Al transmitter. The observed signal enhancement persisted over a broadband frequency range, and thus by optimizing the thermoelasticity of PDMS film and the thermal conductivity of rGO, a promising optoacoustic wave generation was confirmed for laser-induced ultrasound applications.

  20. High-power radio-frequency attenuation device

    DOEpatents

    Kerns, Q.A.; Miller, H.W.

    1981-12-30

    A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

  1. Mapping the radio sky with an interferometric network of low-frequency radio receivers

    NASA Astrophysics Data System (ADS)

    Mezentsev, Andrew; Füllekrug, Martin

    2013-08-01

    The structure of the 100 kHz radio sky is determined with two interferometric networks of 10 radio receivers which are distributed over local areas of ˜1 × 1 km2 and ˜10 × 10 km2. The radio waves arrive at individual receiver pairs with small time differences which are used to determine the arrival direction of the electromagnetic waves including both the bearing and the elevation angle. The results show that the major part of the 100 kHz radio wave energy comes from the horizon at bearings which are consistent with known locations of Long Range Navigation (LORAN) transmitters. Some part of the radio wave energy arrives from the sky at elevation angles which are consistent with the first and second sky hop waves of LORAN transmissions. A minor part of the 100 kHz radio wave energy comes from lightning discharges at distances up to ˜1000 km with bearings which are consistent with lightning locations reported by the arrival time difference (ATD) lightning detection network of the UK Met Office. The angular resolution for mapping the radio sky depends on the network geometry, the instrumental timing accuracy, and on the signal-to-noise ratio of the radio waves. The resulting angular resolution of the interferometric networks used in this study is ˜1° in bearing at zero elevation and several degrees in elevation.

  2. precise clock operating in the radio frequency domain).

    E-print Network

    Weiblen, George D

    365 precise clock operating in the radio frequency domain). In principle, it should be possible to a small spot size to obtain a reasonable intensity. To date, spectroscopy with frequency combs has to Witte et al., all these authors used the fundamental, not a harmonic, of a frequency comb. Despite

  3. Radio frequency identification in the UK: opportunities and challenges

    Microsoft Academic Search

    Peter Jones; Colin Clarke-Hill; Peter Shears; Daphne Comfort; David Hillier

    2004-01-01

    Radio frequency identification (RFID) is the generic name for technologies that use radio waves to automatically identify individual items that carry such identification tags. Unlike barcodes, which need line of sight sensors, RFID tags do not. As the cost of this new technology falls, the take-up rate by the retail industry will be significant, revolutionizing retailers’ control of the product

  4. Radio-Frequency Interference from Digital Television Patrick C. Crane

    E-print Network

    Ellingson, Steven W.

    Radio-Frequency Interference from Digital Television Patrick C. Crane 29 April 2008 Digital television (DTV) signals have intermittently been observed during measurements of radio and includes the VHF television channels 2-6 (54-60, 60-66, 66-72, 76-82, and 82-88 MHz); for example

  5. Supplying the Power Requirements to a Sensor Network Using Radio Frequency Power Transfer

    PubMed Central

    Percy, Steven; Knight, Chris; Cooray, Francis; Smart, Ken

    2012-01-01

    Wireless power transmission is a method of supplying power to small electronic devices when there is no wired connection. One way to increase the range of these systems is to use a directional transmitting antenna, the problem with this approach is that power can only be transmitted through a narrow beam and directly forward, requiring the transmitter to always be aligned with the sensor node position. The work outlined in this article describes the design and testing of an autonomous radio frequency power transfer system that is capable of rotating the base transmitter to track the position of sensor nodes and transferring power to that sensor node. The system's base station monitors the node's energy levels and forms a charge queue to plan charging order and maintain energy levels of the nodes. Results show a radio frequency harvesting circuit with a measured S11 value of ?31.5 dB and a conversion efficiency of 39.1%. Simulation and experimentation verified the level of power transfer and efficiency. The results of this work show a small network of three nodes with different storage types powered by a central base node. PMID:23012506

  6. On Centralized and Distributed Frequency Assignment in Cognitive Radio Based Frequency Hopping Cellular Networks

    E-print Network

    Wichmann, Felix

    On Centralized and Distributed Frequency Assignment in Cognitive Radio Based Frequency Hopping Centre, RWTH Aachen University, Germany, gross@umic.rwth-aachen.de Abstract--Frequency Assignment frequency hopping as one possible frequency assignment approach. In particular we focus our attention

  7. Commissioning of helium injector for coupled radio frequency quadrupole and separated function radio frequency quadrupole accelerator

    SciTech Connect

    Peng, Shixiang, E-mail: sxpeng@pku.edu.cn; Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu [SKLNPT and IHIP, School of Physics, Peking University, Beijing 100871 (China)] [SKLNPT and IHIP, School of Physics, Peking University, Beijing 100871 (China); Zhang, Ailing; Chen, Jia'er [SKLNPT and IHIP, School of Physics, Peking University, Beijing 100871 (China) [SKLNPT and IHIP, School of Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2014-02-15

    A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30 keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 ??mm?mrad and the fraction of He+ is about 99%.

  8. 76 FR 12995 - In the Matter of Certain Radio Control Hobby Transmitters and Receivers and Products Containing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-09

    ...Hobby Transmitters and Receivers and Products Containing...hobby transmitters and receivers and products containing...Commission, 500 E Street, SW., Room 112, Washington...hobby transmitters and receivers and products containing...Commission, 500 E Street, SW., Suite 401,...

  9. Security and Privacy in Radio-Frequency Identification Devices

    Microsoft Academic Search

    Stephen August Weis

    2003-01-01

    Radio Frequency Identification (RFID) systems are a common and useful tool in manufacturing, supply chain management and retail inventory control. Optical barcodes, another common automatic identification system, have been a familiar packaging feature on consumer items for years.

  10. An Investigation of Radio Frequency Auditory Training Units

    ERIC Educational Resources Information Center

    Matkin, Noel D.; Olsen, Wayne

    1973-01-01

    Evaluated were the performances of eight radio frequency systems by means of a measurement procedure said to be applicable to the evaluation of auditory training systems in classrooms for the aurally handicapped. (DB)

  11. 48 CFR 252.211-7006 - Passive Radio Frequency Identification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...passive radio frequency identification (RFID) or item unique identification (IUID...universally identifying physical objects via RFID tags and other means. The standardized...global standards for the adoption of passive RFID technology. Exterior...

  12. Radio-frequency spectroscopy of ultracold atomic Fermi gases

    E-print Network

    Schirotzek, Andre

    2010-01-01

    This thesis presents experiments investigating the phase diagram of ultracold atomic Fermi gases using radio-frequency spectroscopy. The tunability of many experimental parameters including the temperature, the interparticle ...

  13. Olfar, orbiting low frequency antennas for radio astronomy

    Microsoft Academic Search

    Mark Bentum; Chris Verhoeven; Albert-Jan Boonstra

    2009-01-01

    New interesting astronomical science drivers for very low frequency radio astronomy have emerged, ranging from studies of the astronomical dark ages, the epoch of reionization, exoplanets, to ultra-high energy cosmic rays. Huge efforts are currently made to establish low frequency Earthbound instruments, since today’s technology is able to support this. However, astronomical observations with Earth-bound radio telescopes at very low

  14. Investigation of indoor Wireless-N radio frequency signal strength

    Microsoft Academic Search

    Abdul Halim Ali

    2011-01-01

    Wireless local area network has become the most popular networks in connecting to internet especially at home, universities, hotels and workplaces. Therefore understanding the radio frequency behaviour of WLAN is vital in ensuring the best possible coverage. Wireless-N system operators in two frequencies band which are the 2.4GHz ISM band and 5GHz UNII band. However this paper investigates the radio

  15. Multi-dimensional ultra-high frequency passive radio frequency identification tag antenna designs

    E-print Network

    Delichatsios, Stefanie Alkistis

    2006-01-01

    In this thesis, we present the design, simulation, and empirical evaluation of two novel multi-dimensional ultra-high frequency (UHF) passive radio frequency identification (RFID) tag antennas, the Albano-Dipole antenna ...

  16. New method for recovering weak coherent radio frequency signals

    SciTech Connect

    Goree, J.

    1985-03-01

    A single radio frequency lock-in amplifier reduces broadband noise, but not rf pickup of the same frequency as the signal. If this pickup noise is at least 14 dB stronger than broadband noise, after both have passed through the lock-in, then the signal-to-noise ratio can be improved by applying the lock-in output to a second, low frequency lock-in which is synchronized to an independent modulation of the signal. Weak coherent radio frequency signals buried in both rf pickup and broadband nise can be recovered by using this double lock-in method, as demonstrated in a plasma diagnostics experiment.

  17. Joint Statistics of Radio Frequency Interference in Multiantenna Receivers

    Microsoft Academic Search

    Aditya Chopra; Brian L. Evans

    2012-01-01

    Many wireless data communications systems, such as LTE, Wi-Fi, and Wimax, have become or are rapidly becoming interference limited due to radio frequency interference (RFI) generated by both human-made and natural sources. Human-made sources of RFI include uncoordinated devices operating in the same frequency band, devices communicating in adjacent frequency bands, and computational platform subsystems radiating clock frequencies and their

  18. The solar elongation distribution of low-frequency radio bursts

    Microsoft Academic Search

    M. L. Kaiser

    1975-01-01

    Over 500 days of low-frequency (less than 1 MHz) radio observations from the IMP-6 spacecraft have been accumulated to produce a two-dimensional map (frequency vs elongation) of solar type III burst occurrences. This map indicates that most solar bursts in this frequency range are observed at the second harmonic of the plasma frequency, rather than the fundamental. The map also

  19. 47 CFR 76.616 - Operation near certain aeronautical and marine emergency radio frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...aeronautical and marine emergency radio frequencies. 76.616 Section 76.616...COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO...aeronautical and marine emergency radio frequencies. (a) The transmission...

  20. 47 CFR 76.616 - Operation near certain aeronautical and marine emergency radio frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...aeronautical and marine emergency radio frequencies. 76.616 Section 76.616...COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO...aeronautical and marine emergency radio frequencies. (a) The transmission...

  1. Calcium, calpain, and calcineurin in low-frequency depression of transmitter release.

    PubMed

    Silverman-Gavrila, Lorelei B; Praver, Moshe; Mykles, Donald L; Charlton, Milton P

    2013-01-30

    Low-frequency depression (LFD) of transmitter release occurs at phasic synapses with stimulation at 0.2 Hz in both isolated crayfish (Procambarus clarkii) neuromuscular junction (NMJ) preparations and in intact animals. LFD is regulated by presynaptic activity of the Ca(2+)-dependent phosphatase calcineurin (Silverman-Gavrila and Charlton, 2009). Since the fast Ca(2+) chelator BAPTA-AM inhibits LFD but the slow chelator EGTA-AM does not, the Ca(2+) sensor for LFD may be close to a Ca(2+) source at active zones. Calcineurin can be activated by the Ca(2+)-activated protease calpain, and immunostaining showed that both proteins are present at nerve terminals. Three calpain inhibitors, calpain inhibitor I, MDL-28170, and PD150606, but not the control compound PD145305, inhibit LFD both in the intact animal as shown by electromyograms and by intracellular recordings at neuromuscular junctions. Analysis of mini-EPSPs indicated that these inhibitors had minimal postsynaptic effects. Proteolytic activity in CNS extract, detected by a fluorescent calpain substrate, was modulated by Ca(2+) and calpain inhibitors. Western blot analysis of CNS extract showed that proteolysis of calcineurin to a fragment consistent with the constitutively active form required Ca(2+) and was blocked by calpain inhibitors. Inhibition of LFD by calpain inhibition blocks the reduction in phosphoactin and the depolymerization of tubulin that normally occurs in LFD, probably by blocking the dephosphorylation of cytoskeletal proteins by calcineurin. In contrast, high-frequency depression does not involve protein phosphorylation- or calpain-dependent mechanisms. LFD may involve a specific pathway in which local Ca(2+) signaling activates presynaptic calpain and calcineurin at active zones and causes changes of tubulin cytoskeleton. PMID:23365236

  2. Air Band Scanner with Retransmission over Local FM Radio Frequencies Using a

    E-print Network

    Yu, Chansu

    Air Band Scanner with Retransmission over Local FM Radio Frequencies Using a Software Defined Radio it uses [4]. Despite the frequencies only being slightly higher than the FM radio frequency range, air will then be retransmitted, using a BasicTX daughter, over an FM frequency that can be received using a standard FM radio

  3. Radio-Frequency Electron Accelerators for Industrial Applications

    NASA Astrophysics Data System (ADS)

    Cleland, Marshall R.

    2011-02-01

    Two types of radio-frequency electron accelerators are described in this article. They operate in the frequency range of 100-200MHz and are energized with triode or tetrode tubes instead of klystrons. They can provide more powerful electron beams than typical microwave linear accelerators.

  4. Radio-frequency scanning tunnelling microscopy U. Kemiktarak1

    E-print Network

    the dimin- ished high-frequency response of the tunnel current readout circuitry. Here we overcomeLETTERS Radio-frequency scanning tunnelling microscopy U. Kemiktarak1 , T. Ndukum3 , K. C. Schwab3 between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25

  5. Design of a fiber-optic transmitter for microwave analog transmission with high phase stability

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.; Lutes, G. F.; Primas, L. E.; Maleki, L.

    1990-01-01

    The principal considerations in the design of fiber-optic transmitters for highly phase-stable radio frequency and microwave analog transmission are discussed. Criteria for a fiber-optic transmitter design with improved amplitude and phase-noise performance are developed through consideration of factors affecting the phase noise, including low-frequency laser-bias supply noise, the magnitude and proximity of external reflections into the laser, and temperature excursions of the laser-transmitter package.

  6. Preening behavior of adult gyrfalcons tagged with backpack transmitters

    USGS Publications Warehouse

    Booms, T.L.; Schempf, P.F.; Fuller, M.R.

    2011-01-01

    Radio transmitters provide data that enhance understanding of raptor biology (Walls and Kenward 2007) and are now used to answer a multitude of research questions (Meyburg and Fuller 2007). However, transmitters affect the birds that carry them (Barron et al. 2010), and it is important to document and evaluate such effects (Casper 2009). For example, decreased survival has been documented in Prairie Falcons (Falco mexicanus; Steenhof et al. 2006), Northern Goshawks (Accipiter gentilis; Reynolds et al. 2004), and Spotted Owls (Strix occidentalis; Paton et al. 1991) tagged with radio transmitters. However, no such effects were reported for Peregrine Falcons (Falco peregrinus; Fuller et al. 1998, McGrady et al. 2002) and a number of other species (Kenward 2001). White and Garrott (1990) noted that in general, animals tagged with radio transmitters often altered their behaviors for 1–14 d after release during an adjustment period that included increased preening and grooming frequencies. Although more than 90 Gyrfalcons (Falco rusticolus) have been tagged with radio transmitters (e.g., Burnham 2007, McIntyre et al. 2009, T. Booms unpubl. data), the effects of transmitters on this species are not well documented. Anecdotal information suggests some Gyrfalcons might be negatively affected by radio-tagging (Booms et al. 2008). As part of a study investigating Gyrfalcon breeding biology, we conducted opportunistic, focused observations on two radio-tagged adult female Gyrfalcons and their unmarked mates. We here describe and quantify preening behavior of Gyrfalcons shortly after radio-tagging.

  7. The Cubesat Radio Experiment (CURE) and Beyond: Cubesat-based Low Frequency Radio Interferometry

    NASA Astrophysics Data System (ADS)

    Saint-Hilaire, P.; Sundkvist, D. J.; Martinez Oliveros, J. C.; Sample, J. G.; Pulupa, M.; Maruca, B.; Bale, S. D.; Bonnell, J. W.; Mozer, F.; Hurford, G. J.

    2014-12-01

    We have proposed a 3U cubesat, to carry a low-frequency radio receiver into low-Earth orbit to study solar radio bursts induced by solar flares and Coronal Mass Ejections. Because of the reflective properties of the Earth's ionosphere, observations of radio waves around and below 10 MHz must be made from space. The measurements will allow continuous tracking of radio bursts and associated CMEs through the inner heliosphere. These observations are important since such events are the main cause for space weather disturbances. Data products from the mission will primarily be spectra and waveforms of solar radio type II and III bursts, and the direction to the radio source as it propagates through the inner heliosphere. These data products will be available to the community through an automated pipeline nominally within a few hours of downlink. Additional science data products will be sizes of radio sources obtained via lunar occultations, and local ionospheric plasma density and electron temperature. As a first cubesat with a scientific radio instrument at these frequencies, this project is also intended as a path-finder: the instrument and sub-systems can immediately be duplicated in other cubesats, with the goal of providing the first radio interferometric measurements below the ionospheric cutoff.

  8. Characteristics of Radio-Frequency Circuits Utilizing Ferroelectric Capacitors

    NASA Technical Reports Server (NTRS)

    Eskridge, Michael; Gui, Xiao; MacLeod, Todd; Ho, Fat D.

    2011-01-01

    Ferroelectric capacitors, most commonly used in memory circuits and variable components, were studied in simple analog radio-frequency circuits such as the RLC resonator and Colpitts oscillator. The goal was to characterize the RF circuits in terms of frequency of oscillation, gain, etc, using ferroelectric capacitors. Frequencies of oscillation of both circuits were measured and studied a more accurate resonant frequency can be obtained using the ferroelectric capacitors. Many experiments were conducted and data collected. A model to simulate the experimental results will be developed. Discrepancies in gain and frequency in these RF circuits when conventional capacitors are replaced with ferroelectric ones were studied. These results will enable circuit designers to anticipate the effects of using ferroelectric components in their radio- frequency applications.

  9. Magnetoreception in birds: the effect of radio-frequency fields.

    PubMed

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-02-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field. PMID:25540238

  10. 47 CFR 22.657 - Transmitter locations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...1983 (NAD83)): Control transmitter frequency range Protected...of the most powerful mobile transmitter(s) in the system: Mobile unit ERP (watts...Co-channel protection from base transmitters with high antennas....

  11. 47 CFR 22.657 - Transmitter locations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...1983 (NAD83)): Control transmitter frequency range Protected...of the most powerful mobile transmitter(s) in the system: Mobile unit ERP (watts...Co-channel protection from base transmitters with high antennas....

  12. Spectrum Sensing in Cognitive Radios Based on Multiple Cyclic Frequencies

    Microsoft Academic Search

    Jarmo Lundén; Visa Koivunen; Anu Huttunenand; H. Vincent Poor

    2007-01-01

    Cognitive radios sense the radio spectrum in order to find unused frequency\\u000abands and use them in an agile manner. Transmission by the primary user must be\\u000adetected reliably even in the low signal-to-noise ratio (SNR) regime and in the\\u000aface of shadowing and fading. Communication signals are typically\\u000acyclostationary, and have many periodic statistical properties related to the\\u000asymbol

  13. A highly tunable radio frequency filter using bulk ferroelectric materials

    Microsoft Academic Search

    M. K. Roy; C. Kalmar; R. R. Neurgaonkar; J. R. Oliver; D. Dewing

    2004-01-01

    The desirable attribute of software defined radios (SDR) implies that RF Front-ends must be multi-band and frequency agile. Wideband SDRs need a lower size, weight, and power (SWAP) tunable filter technology to meet the military's current and future communications needs. This is essential for the SDR operating in a battery powered environment such as man-portable Joint Tactical Radios (JTRS). The

  14. AURA—A radio frequency extension to IceCube

    NASA Astrophysics Data System (ADS)

    Landsman, H.; Ruckman, L.; Varner, G. S.; IceCube Collaboration

    2009-06-01

    The excellent radio frequency (RF) transparency of cold polar ice, combined with the coherent Cherenkov emission produced by neutrino-induced showers when viewed at wavelengths longer than a few centimeters, has spurred considerable interest in a large-scale radio-wave neutrino detector array. The AURA (Askaryan Under-ice Radio Array) experimental effort, within the IceCube collaboration, seeks to take advantage of the opportunity presented by IceCube [A. Karle, Nucl. Instr. and Meth. A (2009), this issue, doi:10.1016/j.nima.2009.03.180. [1]; A. Achtenberg et al., The IceCube Collaboration, Astropart. Phys. 26 (2006) 155 [2

  15. Predicting low-frequency radio fluxes of known extrasolar planets

    E-print Network

    J. -M. Grießmeier; P. Zarka; H. Spreeuw

    2008-06-02

    Context. Close-in giant extrasolar planets (''Hot Jupiters'') are believed to be strong emitters in the decametric radio range. Aims. We present the expected characteristics of the low-frequency magnetospheric radio emission of all currently known extrasolar planets, including the maximum emission frequency and the expected radio flux. We also discuss the escape of exoplanetary radio emission from the vicinity of its source, which imposes additional constraints on detectability. Methods. We compare the different predictions obtained with all four existing analytical models for all currently known exoplanets. We also take care to use realistic values for all input parameters. Results. The four different models for planetary radio emission lead to very different results. The largest fluxes are found for the magnetic energy model, followed by the CME model and the kinetic energy model (for which our results are found to be much less optimistic than those of previous studies). The unipolar interaction model does not predict any observable emission for the present exoplanet census. We also give estimates for the planetary magnetic dipole moment of all currently known extrasolar planets, which will be useful for other studies. Conclusions. Our results show that observations of exoplanetary radio emission are feasible, but that the number of promising targets is not very high. The catalog of targets will be particularly useful for current and future radio observation campaigns (e.g. with the VLA, GMRT, UTR-2 and with LOFAR).

  16. AURA - A radio frequency extension to IceCube

    E-print Network

    H. Landsman; L. Ruckman; G. S. Varner

    2008-11-15

    The excellent radio frequency transparency of cold polar ice, combined with the coherent Cherenkov emission produced by neutrino-induced showers when viewed at wavelengths longer than a few centimeters, has spurred considerable interest in a large-scale radio-wave neutrino detector array. The AURA (Askaryan Under-ice Radio Array) experimental effort, within the IceCube collaboration, seeks to take advantage of the opportunity presented by IceCube drilling through 2010 to establish the radio frequency technology needed to achieve 100-1000 km^3 effective volumes. In the 2006-2007 Austral summer 3 deep in-ice radio frequency (RF) clusters were deployed at depths of 1300m and 300m on top of the IceCube strings. Additional 3 clusters will be deployed in the Austral summer of 2008-2009. Verification and calibration results from the current deployed clusters are presented, and the detector design and performances are discussed. Augmentation of IceCube with large-scale 1000km^3sr radio and acoustic arrays would extend the physics reach of IceCube into the EeV-ZeV regime and offer substantial technological redundancy.

  17. Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment

    E-print Network

    Le Roy, Robert J.

    Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators techniques using radio-frequency electronics. The primary objective is to frequency stabilize a volt- age is commonly applied to stabilize lasers at optical frequencies. By using only radio- frequency equipment

  18. Low frequency radio spectrum and spectral turnover of LS 5039

    E-print Network

    Sagar Godambe; Subir Bhattacharyya; Nilay Bhatt; Manojendu Choudhury

    2008-07-15

    LS 5039, a possible black hole x-ray binary, was recently observed with Giant Meterwave Radio Telescope. The observed spectrum presented here shows that the spectrum is inverted at the low frequency. When combined with the archival data with orbital phase similar to the present observations, it shows a clear indication of a spectral turnover. The combined data are fitted with a broken power-law and the break frequency signifies a possible spectral turnover of the spectrum around 964 MHz. Truly simultaneous observations in radio wavelength covering a wide range of frequencies are required to fix the spectrum and the spectral turn over which will play a crucial role in developing a deeper understanding of the radio emitting jet in LS 5039.

  19. The characteristics of atmospheric radio frequency discharges with frequency increasing at a constant power density

    SciTech Connect

    Zhang Yuantao; Li Qingquan; Lou Jie; Li Qingmin [School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China)

    2010-10-04

    A computational model is used to investigate the characteristics of atmospheric radio frequency discharges by increasing frequency from 20 to 100 MHz at a constant power density. The simulation results show that increasing frequency can effectively enhance electron density before the transition frequency but after it the ignition is quenched then the electron density decreases. However this simulation also indicates the maximum time-averaged electron energy reduces monotonically with the excitation frequency increasing at a constant power density.

  20. Stabilization of Fundamental-Frequency Microwave Oscillators for Radio-Relay Systems

    Microsoft Academic Search

    H. Yokouchi

    1978-01-01

    The cavity stabilized microwave fundamental oscillator shown in Fig. 1 is conveniently used in IF heterodyne repeater systems for the receiver local oscillator. The frequency stability of the transmitter local oscillator is nearly the same as the receiver local oscillator, and shift oscillator stability determines the overall frequency stability of the transmitter. Harmonics of the shift oscillator do not affect

  1. Optical, thermal, and electrical monitoring of radio-frequency tissue modification.

    PubMed

    Floume, Timmy; Syms, Richard R A; Darzi, Ara W; Hanna, George B

    2010-01-01

    Radio-frequency (rf) tissue fusion involves the sealing of tissue between two electrodes delivering rf currents. Applications include small bowel fusion following anastomosis. The mechanism of adhesion is poorly understood, but one hypothesis is that rf modification is correlated to thermal damage and dehydration. A multimodal monitoring system capable of acquiring tissue temperature, electrical impedance, and optical transmittance at 1325-nm wavelength during rf delivery by a modified Ligasure fusion tool is presented. Measurements carried out on single layers of ex vivo porcine small bowel tissue heated at approximately 500-kHz frequency are correlated with observation of water evaporation and histological studies on full seals. It is shown that the induced current generates a rapid quasilinear rise of temperature until the boiling point of water, that changes in tissue transmittance occur before impedance control is possible, and that a decrease in transmission occurs at typical denaturation temperatures. Experimental results are compared with a biophysical model for tissue temperature and a rate equation model for thermal damage. PMID:20210489

  2. Radio frequency dc-dc power conversion

    E-print Network

    Rivas, Juan, 1976-

    2007-01-01

    THIS THESIS addresses the development of system architectures and circuit topologies for dc-dc power conversion at very high frequencies. The systems architectures that are developed are structured to overcome limitations ...

  3. Mapping the Orion Molecular Cloud Complex in Radio Frequencies

    NASA Astrophysics Data System (ADS)

    Castelaz, Michael W.; Lemly, C.

    2013-01-01

    The purpose of this research project was to create a large-scale intensity map of the Orion Molecular Cloud Complex at a radio frequency of 1420 MHz. A mapping frequency of 1420 MHz was chosen because neutral hydrogen, which is the primary component of the Orion Molecular Complex, naturally emits radio waves at this frequency. The radio spectral data for this project were gathered using a 4.6-m radio telescope whose spectrometer was tuned to 1420 MHz and whose beam width was 2.7 degrees. The map created for this project consisted of an eight-by-eight grid centered on M42 spanning 21.6 degrees per side. The grid consisted of 64 individual squares spanning 2.7 degrees per side (corresponding to the beam width of the telescope). Radio spectra were recorded for each of these individual squares at an IF gain of 18. Each spectrum consisted of intensity on an arbitrary scale from 0 to 10 plotted as a function frequencies ranging from -400 kHz to +100 kHz around the origin of 1420 MHz. The data from all 64 radio spectra were imported into Wolfram Alpha, which was used to fit Gaussian functions to the data. The peak intensity and the frequency at which this peak intensity occurs could then be extracted from the Gaussian functions. Other helpful quantities that could be calculated from the Gaussian functions include flux (integral of Gaussian function over frequency range), average value of intensity (flux integral divided by frequency range), and half maximum of intensity. Because all of the radio spectra were redshifted, the velocities of the hydrogen gas clouds of the Orion Molecular Cloud Complex could be calculated using the Doppler equation. The data extracted from the Gaussian functions were then imported into Mathcad to create 2D grayscale maps with right ascension (RA) on the x-axis, declination on the y-axis, and intensity (or flux, etc.) represented on a scale from black to white (with white representing the highest intensities). These 2D maps were then imported into ImageJ to create 3D surface contour plots with RA on the x-axis, declination on the y-axis, and intensity (or flux, etc.) on the z-axis. The intensity map shows the best radio sources.

  4. Site selection for a radio astronomy observatory in Turkey: atmospherical, meteorological, and radio frequency analyses

    NASA Astrophysics Data System (ADS)

    Küçük, Ibrahim; Üler, Ipek; Öz, ?ükriye; Onay, Sedat; Özdemir, Ali R?za; Gül?en, Mehmet; Sar?kaya, Mikail; Dag˜Tekin, Nazl? Derya; Özeren, Ferhat Fikri

    2012-03-01

    Selecting the future site for a large Turkish radio telescope is a key issue. The National Radio Astronomy Observatory is now in the stage of construction at a site near Karaman City, in Turkey. A single-dish parabolic radio antenna of 30-40 m will be installed near a building that will contain offices, laboratories, and living accommodations. After a systematic survey of atmospheric, meteorological, and radio frequency interference (RFI) analyses, site selection studies were performed in a predetermined location in Turkey during 2007 and 2008. In this paper, we described the experimental procedure and the RFI measurements on our potential candidate's sites in Turkey, covering the frequency band from 1 to 40 GHz.

  5. The solar elongation distribution of low-frequency radio bursts

    NASA Technical Reports Server (NTRS)

    Kaiser, M. L.

    1975-01-01

    Over 500 days of low-frequency (less than 1 MHz) radio observations from the IMP-6 spacecraft have been accumulated to produce a two-dimensional map (frequency vs elongation) of solar type III burst occurrences. This map indicates that most solar bursts in this frequency range are observed at the second harmonic of the plasma frequency, rather than the fundamental. The map also shows that the solar wind electron density varies as an inverse power of heliocentric distance, with the exponent somewhat less than 2 to perhaps 3 or higher.

  6. Radio-Controlled Cyborg Beetles: A Radio-Frequency System for Insect Neural Flight Control

    Microsoft Academic Search

    H. SatoI; Y. Peeri; E. Baghoomian; C. W. Berry; M. M. Maharbiz

    2009-01-01

    We present the first report of radio control of a cyborg beetle in free-flight. The microsystem (Figs. 1,2) consisted of a radio-frequency receiver assembly, a micro battery and a live giant flower beetle platform (Mecynorhina polyphemus or Mecynorhina torquata). The assembly had six electrode stimulators implanted into the left and right optic lobes, brain, posterior pronotum (counter electrode), right and

  7. Radio frequency noise from clinical linear accelerators.

    PubMed

    Burke, B; Lamey, M; Rathee, S; Murray, B; Fallone, B G

    2009-04-21

    There is a great deal of interest in image-guided radiotherapy (IGRT), and to advance the state of IGRT, an integrated linear accelerator-magnetic resonance (linac-MR) system has been proposed. Knowledge of the radiofrequency (RF) emissions near a linac is important for the design of appropriate RF shielding to facilitate the successful integration of these two devices. The frequency spectra of both electric and magnetic fields of RF emission are measured using commercially available measurement probes near the treatment couch in three clinical linac vaults with distinct physical layouts. The magnitude spectrum of the RF power emitted from these three linacs is then estimated. The electric field spectrum was also measured at several distances from the linac modulator in order to assess the effects of variations in spatial location in the treatment vault. A large fraction of RF power is emitted at frequencies below 5 MHz. However, the measured RF power at the Larmor frequency (8.5 MHz) of the proposed 0.2 T MR in the linac-MR (0.4-14.6 microW m(-2)) is still large enough to cause artifacts in MR images. Magnetron-based linacs generally emit much larger RF power than klystron-based linacs. In the frequency range of 1-50 MHz, only slight variation in the measured electric field is observed as a function of measurement position. This study suggests that the RF emissions are strong enough to cause image artifacts in MRI systems. PMID:19336849

  8. Computer simulations of ions in radio-frequency traps

    NASA Technical Reports Server (NTRS)

    Williams, A.; Prestage, J. D.; Maleki, L.; Djomehri, J.; Harabetian, E.

    1990-01-01

    The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime.

  9. A Bio-Inspired Active Radio-Frequency Silicon Cochlea

    Microsoft Academic Search

    Soumyajit Mandal; Serhii M. Zhak; Rahul Sarpeshkar

    2009-01-01

    Fast wideband spectrum analysis is expensive in power and hardware resources. We show that the spectrum-analysis architecture used by the biological cochlea is extremely efficient: analysis time, power and hardware usage all scale linearly with N, the number of output frequency bins, versus N log(N) for the Fast Fourier Transform. We also demonstrate two on-chip radio frequency (RF) spectrum analyzers

  10. Time Flies! Radio Signals Used for Time and Frequency Measurements

    Microsoft Academic Search

    Michael A. Lombardi NIST

    The widespread use of the Global Positioning System (GPS) as a time and frequency measurement reference was discussed in the July-September 2001 issue of Cal Lab. This article describes other radio signals that serve as alternatives or backups to GPS. It describes signals used to calibrate and control frequency standards, and signals that synchronize time-of-day clocks in products including wristwatches,

  11. Radio frequency heating of ceramic windows in fusion applications

    Microsoft Academic Search

    J. D. Fowler Jr.; J. D. Jr

    1981-01-01

    Ceramic windows will be used as material barriers for radio frequency plasma heating in fusion reactors. This report examines the theory behind RF heating phenomena. Heating calculations are presented for various window materials, thicknesses, wavelengths, and power densities. The most pertinent material properties are loss tangent, thermal conductivity, dielectric constant, strength, and radiation resistance. Calculations indicate that among candidate materials,

  12. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Microsoft Academic Search

    Shawn M. Allan; Inessa Baranova; Joseph Poley; Henrique Reis

    2012-01-01

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest

  13. RADIO FREQUENCY ELECTRIC FIELDS PROCESSING OF ORANGE JUICE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The nonthermal process of radio frequency electric fields (RFEF) has been shown to inactivate bacteria in apple juice at moderately low temperatures, but has yet to be extended to inactivate bacteria in orange juice. An 80 kW RFEF pasteurizer was used to process pulp-free orange juice at flow rates ...

  14. INNOVATIVE TECHNOLOGY EVALUATION REPORT: RADIO FREQUENCY HEATING, KAI TECHNOLOGIES, INC.

    EPA Science Inventory

    A demonstration of KAI Technologies in-situ radio frequency heating system for soil treatment was conducted from January 1994 to July 1994 at Kelly Air Force Base in San Antonio, Texas. This demonstration was conducted as a joint effort between the USEPA and the USAF. The technol...

  15. Radio frequency electric fields as a nonthermal process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An overview is presented of the current state of art in microbial inactivation in food products by radio frequency electric fields (RFEF) processing. Critical process parameters determining inactivation are discussed. Some issues are offered that need further investigation in order to commercialize ...

  16. Radio frequency interference of electric motors and associated controls

    Microsoft Academic Search

    M. A. Jabbar; M. A. Rahman

    1991-01-01

    Problems of radio-frequency interference (RFI) caused by electric motors used in appliances are discussed in general terms, and some possible solutions are given. Elimination of such noise or suppression to permissible levels is difficult and expensive. Various aspects of motor design, like electric\\/magnetic loading ratio, commutation and sparkling, and brushes and brush gears, which all affect RFI, are discussed. Suppression

  17. INNOVATIVE TECHNOLOGY EVALUATION REPORT: RADIO FREQUENCY HEATING, KAI TECHNOLOGIES, INC.

    EPA Science Inventory

    A demonstration of KAI Technologies in-situ radio frequency heating system for soil treatment was conducted from January 1994 to July 1994 at Kelly Air Force Base in San Antonio, Texas. his demonstration was conducted as a joint effort between the USEPA and the USAF. he technolog...

  18. Magnetically programmable surface acoustic wave radio frequency identification tags

    NASA Astrophysics Data System (ADS)

    Chin, Matthew; Buford, Benjamin; Dhagat, Pallavi

    2011-04-01

    A reconfigurable surface acoustic wave reflector using an integrated magnetoresistive bit was fabricated and evaluated for use in programmable radio frequency identification tags. It is shown that two distinct reflectivities can be achieved depending on the magnetic state of the bit. The experimental results are compared with theoretical calculations of optimal reflectivities achievable from resistively loaded surface acoustic wave transducers.

  19. 29. View of typical radio frequency monitor group electronic tubetype ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. View of typical radio frequency monitor group electronic tube-type cabinet. System is water-cooled with antenna assist. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  20. Surface Studies on Niobium for Superconductivity Radio Frequency (SRF) Accelerator

    E-print Network

    Shaw, Leah B.

    Surface Studies on Niobium for Superconductivity Radio Frequency (SRF) Accelerator Hui Tian College Kelley, Professor of Applied Science Abstract Niobium rf superconductivity is a nanoscale, near-surface-off angle) XPS have been confounded by the effect of surface roughness. The problem was avoided here by

  1. Waste of radio frequency signal analysis for wireless energy harvester

    Microsoft Academic Search

    Mohd Aminurrahim bin Othman

    2010-01-01

    Process by which energy is derived from external sources like thermal energy, wind energy and kinetic energy, captured and stored are called `Energy Harvesting' or `Energy Scavenging'. Normally this method is applied to small autonomous robot, wearable electronic devices and wireless sensor networks. Firstly, radio frequency (RF) radiation is a subset of electromagnetic radiation with a wavelength of 100km to

  2. Geophysical subsurface probing with radio-frequency interferometry

    Microsoft Academic Search

    J. A. KONG; L. Tsang; GENE SIMMONS

    1974-01-01

    The radio-frequency interferometry method can be used to probe interiors of celestial bodies and terrestrial areas with low conductivity. Several glaciers have been studied with this technique. An experiment based on this method was designed for Apollo 17 to examine the lunar subsurface. In order to interpret the interference patterns, We have studied theoretically the electromagnetic fields due to a

  3. Radio Frequency Identification (RFID) Middleware for Existing Data Collection Systems

    Microsoft Academic Search

    John Manilla

    2007-01-01

    Two of the largest consumers of industrial products in the World, the US Department of Defense and Wal-Mart Stores, now require their suppliers to ship goods containing Radio Frequency Identification (RFID) tags in addition to the familiar barcode labels. This requirement has created the need within the industrial manufacturing and distribution industries for software that allows these concerns to quickly

  4. MICROWAVE AND RADIO FREQUENCY POWER APPLICATIONS IN AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential for agricultural applications of radio-frequency (RF) energy for the solution of various problems in agricultural production, crop handling and storage, and product preservation and conditioning has been considered for many years. With the development of economical microwave power equ...

  5. Authentication of Radio Frequency Identification Devices Using Electronic Characteristics

    ERIC Educational Resources Information Center

    Chinnappa Gounder Periaswamy, Senthilkumar

    2010-01-01

    Radio frequency identification (RFID) tags are low-cost devices that are used to uniquely identify the objects to which they are attached. Due to the low cost and size that is driving the technology, a tag has limited computational capabilities and resources. This limitation makes the implementation of conventional security protocols to prevent…

  6. Radio Frequency Noise From the Modulator of a Linac

    Microsoft Academic Search

    M. Lamey; S. Rathee; L. Johnson; M. Carlone; E. Blosser; B. G. Fallone

    2010-01-01

    A novel approach to image-guided radiotherapy being undertaken by a few groups involves the integration of a linac with a magnetic resonance imager (MRI). In order to successfully combine a linac with a MRI, it is important to understand the characteristics and major sources of radio frequency (RF) noise from the pulse power modulator of a linac since these may

  7. Radio-frequency and microwave energies, magnetic and electric fields

    NASA Technical Reports Server (NTRS)

    Michaelson, S. M.

    1975-01-01

    The biological effects of radio frequency, including microwave, radiation are considered. Effects on body temperature, the eye, reproductive systems, internal organs, blood cells, the cardiovascular system, and the central nervous system are included. Generalized effects of electric and magnetic fields are also discussed. Experimentation with animals and clinical studies on humans are cited, and possible mechanisms of the effects observed are suggested.

  8. Radio Frequency Telemetry System for Sensors and Actuators

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor); Miranda, Felix A. (Inventor)

    2003-01-01

    The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote poweringheceiving device. Such technology has many applications, but is especially useful in the biomedical area.

  9. Electron-beam controlled radio frequency discharges for plasma processing

    E-print Network

    Kushner, Mark

    plasma ICP etching reactors.5­9 In these devices, power deposition from the inductively coupled electric During plasma etching and deposition of semiconductor materials, it is desirable to have separate control in reactive ion etching discharges since the radio frequency rf voltage applied to the substrate both

  10. MICROWAVE AND RADIO-FREQUENCY POWER APPLICATIONS IN AGRICULTURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A brief review is presented of potential applications for radio-frequency and microwave power applications in agriculture. Included are applications for stored-product insect control, seed treatment to improve germination and seedling performance, conditioning of products to improve nutritional val...

  11. Radio frequency excited CO/sub 2/ waveguide lasers

    SciTech Connect

    Sinclair, R.L.; Tulip, J.L.

    1984-10-01

    This paper reports on the operation of radio frequency (rf) excited carbon dioxide waveguide lasers. An efficiency of greater than 10% has been achieved with a maximum power of 21 W. The effects of bore size, waveguide fabrication techniques, and gas mixture are discussed.

  12. Determining radio frequency heating uniformity in mixed beans for disinfestations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our laboratory collaborates with USDA-ARS in Parlier, CA in developing thermal treatments based on radio frequency (RF) energy for insect control in legumes to meet postharvest phytosanitary regulations for international market. Our current study focuses on lentils and chickpeas that are two importa...

  13. Radio Frequency Spectra of 388 Bright 74 MHz Sources

    E-print Network

    J. F. Helmboldt; N. E. Kassim; A. S. Cohen; W. M. Lane; T. J. Lazio

    2007-07-23

    As a service to the community, we have compiled radio frequency spectra from the literature for all sources within the VLA Low Frequency Sky Survey (VLSS) that are brighter than 15 Jy at 74 MHz. Over 160 references were used to maximize the amount of spectral data used in the compilation of the spectra, while also taking care to determine the corrections needed to put the flux densities from all reference on the same absolute flux density scale. With the new VLSS data, we are able to vastly improve upon previous efforts to compile spectra of bright radio sources to frequencies below 100 MHz because (1) the VLSS flux densities are more reliable than those from some previous low frequency surveys and (2) the VLSS covers a much larger area of the sky (declination >-30 deg.) than many other low frequency surveys (e.g., the 8C survey). In this paper, we discuss how the spectra were constructed and how parameters quantifying the shapes of the spectra were derived. Both the spectra and the shape parameters are made available here to assist in the calibration of observations made with current and future low frequency radio facilities.

  14. Radio frequency noise from clinical linear accelerators

    Microsoft Academic Search

    There is a great deal of interest in image-guided radiotherapy (IGRT), and to advance the state of IGRT, an integrated linear accelerator-magnetic resonance (linac-MR) system has been proposed. Knowledge of the radiofrequency (RF) emissions near a linac is important for the design of appropriate RF shielding to facilitate the successful integration of these two devices. The frequency spectra of both

  15. Radio frequency noise from clinical linear accelerators

    Microsoft Academic Search

    B. Burke; M. Lamey; S. Rathee; B. Murray; B. G. Fallone

    2009-01-01

    There is a great deal of interest in image-guided radiotherapy (IGRT), and to advance the state of IGRT, an integrated linear accelerator-magnetic resonance (linac-MR) system has been proposed. Knowledge of the radiofrequency (RF) emissions near a linac is important for the design of appropriate RF shielding to facilitate the successful integration of these two devices. The frequency spectra of both

  16. Coplanar waveguide radio frequency ferromagnetic parametric amplifier

    Microsoft Academic Search

    Mingqiang Bao; Alexander Khitun; Yina Wu; Joo-Young Lee; Kang L. Wang; Ajey P. Jacob

    2008-01-01

    In this letter, we report a coplanar waveguide ferromagnetic parametric amplifier fabricated on a ferromagnetic Permalloy thin film. It shows a power gain of 4 dB at 1.15 GHz when the pump power is 11.1 dBm at the pump frequency of 2.30 GHz under the bias field of 13 Oe. This prototype ferromagnetic device can be integrated with the complementary

  17. PERCUTANEOUS RADIO FREQUENCY ABLATION OF SMALL RENAL TUMORS: INITIAL RESULTS

    PubMed Central

    PAVLOVICH, CHRISTIAN P.; WALTHER, McCLELLAN M.; CHOYKE, PETER L.; PAUTLER, STEPHEN E.; CHANG, RICHARD; LINEHAN, W. MARSTON; WOOD, BRADFORD J.

    2014-01-01

    Purpose Thermal tissue ablation with radio frequency energy is an experimental treatment of renal tumor. We report early results of an ongoing trial of percutaneous radio frequency ablation for small renal tumors. Materials and Methods Patients with percutaneously accessible renal tumors were evaluated for radio frequency ablation. Tumors were solid on computerized tomography (CT), 3 cm. or less in diameter and enlarging during at least 1 year. Ablation was performed at the Interventional Radiology suite under ultrasound and/or CT guidance. A 50 W., 460 kHz. electrosurgical generator delivered radio frequency energy via a percutaneously placed 15 gauge coaxial probe. At least 2, 10 to 12-minute ablation cycles were applied to each lesion. Patients were observed overnight before discharge from hospital and reevaluated 2 months later. Results A total of 24 ablations were performed in 21 patients with renal tumor, including solid von Hippel-Lindau clear cell tumor in 19 and hereditary papillary renal cancer 2. Most (22 of 24) procedures were performed with patients under conscious sedation. At 2 months postoperatively mean tumor diameter plus or minus standard deviation decreased from 2.4 ± 0.4 to 2.0 ± 0.5 cm. (p = 0.001), and a majority of tumors (19 of 24, 79%) ceased to be enhanced on contrast CT. Mean serum creatinine plus or minus standard deviation was unchanged during this interval (1.0 ± 0.2 mg./dl.). No major and 4 minor complications were encountered, including 2 episodes each of transient psoas pain and flank skin numbness. Conclusions Percutaneous radio frequency ablation of small renal tumor is well tolerated and minimally invasive. It will remain experimental until procedural and imaging parameters that correlate with tumor destruction are validated. PMID:11743264

  18. "Magic" radio-frequency dressing for trapped atomic microwave clocks

    E-print Network

    Kazakov, Georgy A

    2014-01-01

    It has been proposed to use magnetically trapped atomic ensembles to enhance the interrogation time in microwave clocks. To mitigate the perturbing effects of the magnetic trap, "near-magic field" configurations are employed, where the involved clock transition becomes independent of the atoms potential energy to first order. Still, higher order effects are a dominating source for dephasing, limiting the perfomance of this approach. Here we propose a simple method to cancel the energy dependence to both, first and second order, using weak radio-frequency dressing. We give values for dressing frequencies, amplitudes, and trapping fields for 87Rb atoms and investigate quantitatively the robustness of these "second-order magic" conditions to variations of the system parameters. We conclude that radio-frequency dressing can suppress field-induced dephasing by at least one order of magnitude for typical experimental parameters.

  19. Magic radio-frequency dressing for trapped atomic microwave clocks

    NASA Astrophysics Data System (ADS)

    Kazakov, G. A.; Schumm, T.

    2015-02-01

    It has been proposed to use magnetically trapped atomic ensembles to enhance the interrogation time in microwave clocks. To mitigate the perturbing effects of the magnetic trap, near-magic-field configurations are employed, where the involved clock transition becomes independent of the atom's potential energy to first order. Still, higher order effects are a dominating source for dephasing, limiting the performance of this approach. Here we propose a simple method to cancel the energy dependence to both first and second order, using weak radio-frequency dressing. We give values for dressing frequencies, amplitudes, and trapping fields for 87Rb atoms and investigate quantitatively the robustness of these second-order-magic conditions to variations of the system parameters. We conclude that radio-frequency dressing can suppress field-induced dephasing by at least one order of magnitude for typical experimental parameters.

  20. Presented at "RFI2004: Workshop on Mitigation of Radio Frequency Interference in Radio Astronomy"; Penticton, Canada, 16-18 July 2004

    E-print Network

    Ellingson, Steven W.

    Presented at "RFI2004: Workshop on Mitigation of Radio Frequency Interference in Radio Astronomy Driel ICSU Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science (IUCAF the radio frequency bands allocated for astronomical use. Radio telescopes are very sensitive, and their far

  1. On the Carrier Frequency Offset Estimation for Frequency Hopping Burst Mode Mobile Radio

    Microsoft Academic Search

    Gokhan M. Guvensen; Y. Tanik; A. O. Yilmaz

    2010-01-01

    In this paper, we evaluate the Cramer-Rao bounds (CRB) for the estimation of the carrier frequency offset (CFO) for general QAM modulations with no knowledge of the transmitted sequence (blind operation) in frequency hopping (FH) based short burst mode mobile radios. We investigate the blind CFO estimation problem in FH based mobile system that uses multiple short narrowband bursts in

  2. The radio astronomy explorer satellite, a low-frequency observatory.

    NASA Technical Reports Server (NTRS)

    Weber, R. R.; Alexander, J. K.; Stone, R. G.

    1971-01-01

    The RAE-1 is the first spacecraft designed exclusively for radio astronomical studies. It is a small, but relatively complex, observatory including two 229-meter antennas, several radiometer systems covering a frequency range of 0.2 to 9.2 MHz, and a variety of supporting experiments such as antenna impedance probes and TV cameras to monitor antenna shape. Since its launch in July, 1968, RAE-1 has sent back some 10 billion data bits per year on measurements of long-wavelength radio phenomena in the magnetosphere, the solar corona, and the Galaxy. In this paper we describe the design, calibration, and performance of the RAE-1 experiments in detail.

  3. 76 FR 58142 - Defense Federal Acquisition Regulation Supplement; Passive Radio Frequency Identification (DFARS...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...passive radio frequency identification (RFID). DATES: Effective Date: September...passive radio frequency identification (RFID). II. Discussion and Analysis DoD received...rule. Comment: A respondent stated that RFID tags will play an expanded role in...

  4. 47 CFR 76.616 - Operation near certain aeronautical and marine emergency radio frequencies.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Operation near certain aeronautical and marine emergency radio frequencies. 76.616 Section...Technical Standards § 76.616 Operation near certain aeronautical and marine emergency radio frequencies. (a) The...

  5. 47 CFR 76.616 - Operation near certain aeronautical and marine emergency radio frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Operation near certain aeronautical and marine emergency radio frequencies. 76.616 Section...Technical Standards § 76.616 Operation near certain aeronautical and marine emergency radio frequencies. (a) The...

  6. OLFAR - orbiting low frequency array; using a satellite swarm for building a space-based radio telescope for low frequencies

    Microsoft Academic Search

    M. J. Bentum; A. J. Boonstra; C. J. M. Verhoeven; Veen van der A. J; E. K. A. Gill; N. Saks; H. Falcke; M. Klein-Wolt; R. T. Rajan; S. J. Wijnholds; M. Arts; Klooster van't K; F. Beliën; A. Meijerink; B. Monna; J. Rotteveel; M. A. Boer; E. Bongers; E. Boom; Tuijl van E; Staveren van A

    2010-01-01

    In radio astronomy, as in astronomy in general, a wide range of frequencies is observed as each spectral band offers a unique window to study astrophysical phenomena. In the recent years, new observatories have been designed and built at the extreme limits of the radio spectrum. For the low frequencies several Earth-based radio telescopes are constructed at this moment. In

  7. Comparative study on various radio frequency spectrum sensing techniques

    NASA Astrophysics Data System (ADS)

    Gondesi, Raveendhar Reddy

    2011-12-01

    Cognitive radio (CR) is a self-monitoring wireless communication system. CR can utilize the radio frequency spectrum efficiently. The main objective of cognitive radio is to detect the primary user signal and determine whether a channel is free or not. The CR user can opportunistically use those idle spectrum bands without causing harmful interference to the licensed/primary users. There are several spectrum sensing techniques which can serve this purpose. In this research, the computational complexities for different local spectrum sensing techniques are calculated. Using the results obtained from computational complexities, the energy efficient and time efficient techniques are determined. From the results obtained in local sensing techniques, the cost efficient and bandwidth efficient combination for cooperative spectrum sensing is determined. Using MATLAB programming, the receiver operating characteristic curves for these spectrum sensing techniques are plotted.

  8. Near-field microwave magnetic nanoscopy of superconducting radio frequency cavity materials

    E-print Network

    Anlage, Steven

    Near-field microwave magnetic nanoscopy of superconducting radio frequency cavity materials Tamin measurement of the RF critical field on superconducting radio frequency (SRF) cavity materials is a key step to mass-produce bulk Nb Superconducting Radio Frequency (SRF) cavities with consistent high accelerating

  9. SUBJECT: Effective Date: Policy Number: Radio Frequency Spectrum 12-15-10 4-011

    E-print Network

    Glebov, Leon

    SUBJECT: Effective Date: Policy Number: Radio Frequency Spectrum 12-15-10 4-011 Supersedes: Page. POLICY STATEMENT: Radio frequency spectrum is a critical resource that must be managed to eliminate acquisitions of devices or systems that radiate or receive radio frequency energy by university entities must

  10. Numerical studies of current generation by radio-frequency traveling waves

    E-print Network

    Karney, Charles

    Numerical studies of current generation by radio-frequency traveling waves Charles F. F. Karney January 1979; final manuscript received 7 May 1979) By injecting radio-frequency traveling waves of the fusion power output. Recently,' the damping of high-phase-velocity radio- frequency traveling waves has

  11. Simplified radio-frequency generator for driving ion guides, traps, and other capacitive loads

    E-print Network

    Anderson, Scott L.

    NOTES Simplified radio-frequency generator for driving ion guides, traps, and other capacitive 2000 We report the design and construction details for a very simple radio-frequency rf generator-5 A few years ago, we published the design for a high voltage radio-frequency rf oscillator circuit

  12. Investigation of the Radio Frequency Characteristics of CMOS Electrostatic Discharge Protection Devices

    E-print Network

    Anlage, Steven

    1 Investigation of the Radio Frequency Characteristics of CMOS Electrostatic Discharge Protection junctions may also rectify radio-frequency signals coupled onto CMOS data lines from incidental or malicious in logic levels. This paper presents a theoretical, numerical and experimental investigation of the radio-frequency

  13. Efficient scalar spin relaxation in the rotating frame for matched radio-frequency fields

    E-print Network

    Skrynnikov, Nikolai

    Efficient scalar spin relaxation in the rotating frame for matched radio-frequency fields N. R in the presence of two radio-frequency fields applied to each of the spins individually. It is demonstrated that the relaxation rate constant T1 1 of the spin I due to scalar relaxation sharply increases when the two radio-frequency

  14. EVALUATION OF THE KURTOSIS ALGORITHM IN DETECTING RADIO FREQUENCY INTERFERENCE FROM MULTIPLE SOURCES

    E-print Network

    Ruf, Christopher

    EVALUATION OF THE KURTOSIS ALGORITHM IN DETECTING RADIO FREQUENCY INTERFERENCE FROM MULTIPLE algorithm in detecting multiple-source Radio Frequency Interference (RFI) is characterized. A new RFI to large number of RFI sources. Index Terms ­ Microwave radiometer, radio frequency interference, kurtosis

  15. SIMULATION OF RADIO-FREQUENCY ABLATION USING COMPOSITE FINITE ELEMENT METHODS

    E-print Network

    Preusser, Tobias

    SIMULATION OF RADIO-FREQUENCY ABLATION USING COMPOSITE FINITE ELEMENT METHODS T. PREUSSER AND H¨urich, Winterthurerstrasse 190, 8057 Z¨urich, Switzerland This paper deals with a model for the simulation of the radio-frequency step size. A multigrid solver further enhances the performance of the method. 1. Introduction The radio-frequency

  16. Multi-Scale Optimization of the Probe Placement for Radio-Frequency Ablation ,

    E-print Network

    Preusser, Tobias

    Multi-Scale Optimization of the Probe Placement for Radio-Frequency Ablation , Inga Altrogge in radio-frequency (RF) ablation. The model is based on a system of partial differential equations which to artificial test scenarios as well as a comparison to a real RF ablation are presented. Key words: Radio-Frequency

  17. Verification of particle simulation of radio frequency waves in fusion Animesh Kuley,1,2,a)

    E-print Network

    Lin, Zhihong

    Verification of particle simulation of radio frequency waves in fusion plasmas Animesh Kuley,1,2,a (Received 14 May 2013; accepted 8 October 2013; published online 24 October 2013) Radio frequency (RF) waves. INTRODUCTION The importance of radio frequency (RF) waves as a source for heating and current drive has been

  18. Tidal currents in the northwestern Adriatic: High-frequency radio observations and

    E-print Network

    Tidal currents in the northwestern Adriatic: High-frequency radio observations and numerical model] A 2-year deployment of high-frequency radio current meters along the Italian coast of the northwestern in the northwestern Adriatic: High-frequency radio observations and numerical model predictions, J. Geophys. Res., 112

  19. Bolometric and nonbolometric radio frequency detection in a metallic single-walled carbon nanotube

    E-print Network

    Kim, Philip

    Bolometric and nonbolometric radio frequency detection in a metallic single-walled carbon nanotube 2011; published online 31 May 2011 We characterize radio frequency detection in a high-quality metallic difficult. The goals of the present work are to study radio frequency rf detec- tion over a range

  20. Simple radio-frequency power source for ion guides and ion traps Ronald M. Jones

    E-print Network

    Anderson, Scott L.

    Simple radio-frequency power source for ion guides and ion traps Ronald M. Jones Department oscillator circuit, designed to power radio-frequency rf ion guides and traps, is described. The rf circuit by inhomoge- neous radio-frequency rf fields, in some cases with addi- tional inhomogeneous direct current dc

  1. Radio-frequency-mediated dipolar recoupling among half-integer quadrupolar spins

    E-print Network

    Griffin, Robert G.

    Radio-frequency-mediated dipolar recoupling among half-integer quadrupolar spins Marc Baldus quadrupolar spins in the presence of an appropriate radio-frequency field. Experimental and theoretical in close spatial proximity. Unfortunately, most spin-1/2 methods involving radio frequency rf irradiation

  2. Radio Frequency Charge Parity Meter M. D. Schroer,1,* M. Jung,1

    E-print Network

    Petta, Jason

    Radio Frequency Charge Parity Meter M. D. Schroer,1,* M. Jung,1 K. D. Petersson,1 and J. R. Petta1 measurement by detecting the radio frequency signal that is reflected by a lumped-element resonator coupled of the mesoscopic admittance of DQD devices. In this Letter, we probe spin-dependent effects in the radio frequency

  3. Imaging interplanetary CMEs at radio frequency from solar polar orbit

    NASA Astrophysics Data System (ADS)

    Wu, Ji; Sun, Weiying; Zheng, Jianhua; Zhang, Cheng; Liu, Hao; Yan, Jingye; Wang, Chi; Wang, Chuanbing; Wang, Shui

    2011-09-01

    Coronal mass ejections (CMEs) represent a great concentration of mass and energy input into the lower corona. They have come to be recognized as the major driver of physical conditions change in the Sun-Earth system. Consequently, observations of CMEs are important for understanding and ultimately predicting space weather conditions. This paper discusses a proposed mission, the Solar Polar Orbit Radio Telescope (SPORT) mission, which will observe the propagation of interplanetary CMEs to distances of near 0.35 AU from the Sun. The orbit of SPORT is an elliptical solar polar orbit. The inclination angle between the orbit and ecliptic plane should be about 90°. The main payload on board SPORT will be an imaging radiometer working at the meter wavelength band (radio telescope), which can follow the propagation of interplanetary CMEs. The images that are obtained by the radio telescope embody the brightness temperature of the objectives. Due to the very large size required for the antenna aperture of the radio telescope, we adopt interferometric imaging technology to reduce it. Interferometric imaging technology is based on indirect spatial frequency domain measurements plus Fourier transformation. The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind ion instrument, an energetic particle detector, a magnetometer, a wave detector and a solar radio burst spectrometer.

  4. Predictions for high-frequency radio surveys of extragalactic sources

    NASA Astrophysics Data System (ADS)

    de Zotti, G.; Ricci, R.; Mesa, D.; Silva, L.; Mazzotta, P.; Toffolatti, L.; González-Nuevo, J.

    2005-03-01

    We present detailed predictions of the contributions of the various source populations to the counts at frequencies of tens of GHz. New evolutionary models are worked out for flat-spectrum radio quasars, BL Lac objects, and steep-spectrum sources. Source populations characterized by spectra peaking at high radio frequencies, such as extreme GPS sources, ADAF/ADIOS sources and early phases of ?-ray burst afterglows are also dealt with. The counts of different populations of star-forming galaxies (normal spirals, starbursts, high-z galaxies detected by SCUBA and MAMBO surveys, interpreted as proto-spheroidal galaxies) are estimated taking into account both synchrotron and free-free emission, and dust re-radiation. Our analysis is completed by updated counts of Sunyaev-Zeldovich effects in clusters of galaxies and by a preliminary estimate of galactic-scale Sunyaev-Zeldovich signals associated to proto-galactic plasma.

  5. Radio frequency analog electronics based on carbon nanotube transistors.

    PubMed

    Kocabas, Coskun; Kim, Hoon-Sik; Banks, Tony; Rogers, John A; Pesetski, Aaron A; Baumgardner, James E; Krishnaswamy, S V; Zhang, Hong

    2008-02-01

    The potential to exploit single-walled carbon nanotubes (SWNTs) in advanced electronics represents a continuing, major source of interest in these materials. However, scalable integration of SWNTs into circuits is challenging because of difficulties in controlling the geometries, spatial positions, and electronic properties of individual tubes. We have implemented solutions to some of these challenges to yield radio frequency (RF) SWNT analog electronic devices, such as narrow band amplifiers operating in the VHF frequency band with power gains as high as 14 dB. As a demonstration, we fabricated nanotube transistor radios, in which SWNT devices provide all of the key functions, including resonant antennas, fixed RF amplifiers, RF mixers, and audio amplifiers. These results represent important first steps to practical implementation of SWNTs in high-speed analog circuits. Comparison studies indicate certain performance advantages over silicon and capabilities that complement those in existing compound semiconductor technologies. PMID:18227509

  6. Radio Spectroscopy with High Time and Frequency Resolution

    NASA Astrophysics Data System (ADS)

    Aurass, H.; Mann, G.; Hanschur, U.; Zlobec, P.

    Two multichannel spectral magnifiers supplement the sweep broadband observations at AI Potsdam during special campaigns. The 48 channel decimeter spectrograph and the 180 channel meter chirp transform polarimeter enable the detailed analysis of fine structures in radio bursts with one order of magnitude improved frequency and time resolution and twice the sensitivity of the sweep receivers. We present some observations and cross-check the spectral-polarimeter data with single frequency polarimetry at OA Trieste. Thanks to the improved sensitivity we obtain a new quality of fine structure data. Accepting the repeated beam injection - mechanism of broadband pulsations, the data lead us to a revised and simplified source model of the various radio burst continuum fine structures.

  7. Perforated-Layer Implementation Of Radio-Frequency Lenses

    NASA Technical Reports Server (NTRS)

    Dolgin, Benjamin P.

    1996-01-01

    Luneberg-type radio-frequency dielectric lenses made of stacked perforated circular dielectric sheets, according to proposal. Perforation pattern designed to achieve required spatial variation of permittivity. Consists of round holes distributed across face of each sheet in "Swiss-cheese" pattern, plus straight or curved slots that break up outer parts into petals in "daisy-wheel" pattern. Holes and slots made by numerically controlled machining.

  8. Tests of niobium cathode for the superconducting radio frequency gun

    Microsoft Academic Search

    Qiang Zhao; Triveni Srinivasan-Rao; M. Cole

    2003-01-01

    For the superconducting all-niobium photocathode radio frequency gun project, we have studied the surface preparation techniques of the niobium cathode material. The quantum efficiency (QE) of high purity niobium (RRR=250) has been intensively measured at room temperature on a dedicated DC system. After buffer chemical polishing or electrolytic polishing, the initial QE is in the order of 10-7 range tested

  9. CMOS compatible integrated all-optical radio frequency spectrum analyzer.

    PubMed

    Ferrera, Marcello; Reimer, Christian; Pasquazi, Alessia; Peccianti, Marco; Clerici, Matteo; Caspani, Lucia; Chu, Sai T; Little, Brent E; Morandotti, Roberto; Moss, David J

    2014-09-01

    We report an integrated all-optical radio frequency spectrum analyzer based on a ~4 cm long doped silica glass waveguide, with a bandwidth greater than 2.5 THz. We use this device to characterize the intensity power spectrum of ultrahigh repetition rate mode-locked lasers at repetition rates up to 400 GHz, and observe dynamic noise related behavior not observable with other techniques. PMID:25321527

  10. Multiplexing of Radio-Frequency Single Electron Transistors

    NASA Technical Reports Server (NTRS)

    Stevenson, Thomas R.; Pellerano, F. A.; Stahle, C. M.; Aidala, K.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    We present results on wavelength division multiplexing of radio-frequency single electron transistors. We use a network of resonant impedance matching circuits to direct applied rf carrier waves to different transistors depending on carrier frequency. A two-channel demonstration of this concept using discrete components successfully reconstructed input signals with small levels of cross coupling. A lithographic version of the rf circuits had measured parameters in agreement with electromagnetic modeling, with reduced cross capacitance and inductance, and should allow 20 to 50 channels to be multiplexed.

  11. A simple Lorenz circuit and its radio frequency implementation.

    PubMed

    Blakely, Jonathan N; Eskridge, Michael B; Corron, Ned J

    2007-06-01

    A remarkably simple electronic circuit design based on the chaotic Lorenz system is described. The circuit consists of just two active nonlinear elements (high-speed analog multipliers) and a few passive linear elements. Experimental implementations of the circuit exhibit the classic butterfly attractor and the hysteretic transition from steady state to chaos observed in the Lorenz equations. The simplicity of the circuit makes it suitable for radio frequency applications. The power spectrum of the observed oscillations displays a peak frequency as high as 930 kHz and significant power beyond 1 MHz. PMID:17614666

  12. A Radio Frequency Helical Deflector for keV Electrons

    E-print Network

    Gevorgian, Leckdar; Kakoyan, Vanik; Margaryan, Amur; Annand, John

    2014-01-01

    This paper describes a helical deflector to perform circular sweeps of keV electrons by means of radio frequency fields in a frequency range 500-1000 MHz. By converting the time dependence of incident electrons to a hit position dependence on a circle, this device can potentially achieve extremely precise timing. The system can be adjusted to the velocity of the electrons to exclude the reduction of deflection sensitivity due to finite transit time effects. The deflection electrodes form a resonant circuit, with quality factor Q in excess of 100, and at resonance the sensitivity of the deflection system is around 1~mm per V of applied RF input.

  13. A radio frequency helical deflector for keV electrons

    NASA Astrophysics Data System (ADS)

    Gevorgian, L.; Ajvazyan, R.; Kakoyan, V.; Margaryan, A.; Annand, J. R. M.

    2015-06-01

    This paper describes a helical deflector to perform circular sweeps of keV electrons by means of radio frequency fields in a frequency range of 500-1000 MHz. By converting the time dependence of incident electrons to a hit position dependence on a circle, this device can potentially achieve extremely precise timing. The system can be adjusted to the velocity of the electrons to exclude the reduction of deflection sensitivity due to finite transit time effects. The deflection electrodes form a resonant circuit, with quality factor Q in excess of 100, and at resonance the sensitivity of the deflection system is around 1 mm per V of applied RF input.

  14. New observations of the low frequency interplanetary radio emissions

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.

    1991-01-01

    Recent Voyager 1 observations reveal reoccurrences of the low frequency interplanetary radio emissions. Three of the new events are weak transient events which rise in frequency from the range of 2-2.5 kHz to about 3 kHz with drift rates of approximately 1.5 kHz/year. The first of the transient events begins in mid-1989 and the more recent pair of events both were first detected in late 1991. In addition, there is an apparent onset of a 2-kHz component of the emission beginning near day 70 of 1991. The new transient emissions are barely detectable on Voyager 1 and are below the threshold of detectability on Voyager 2, which is less sensitive than Voyager 1. The new activity provides new opportunities to test various theories of the triggering, generation, and propagation of the outer heliospheric radio emissions and may signal a response of the source of the radio emissions to the increased solar activity associated with the recent peak in the solar cycle.

  15. Background radio-frequency radiation and its impact on radio astronomy Michelle C. Storey, Bruce MacA Thomas and John M. Sarkissian

    E-print Network

    Sarkissian, John M.

    1 Background radio-frequency radiation and its impact on radio astronomy Michelle C. Storey, Bruce 1710 Email:mstorey@atnf.csiro.au Abstract: The use of radio-frequency telecommunications equipment is dramatically increasing, and one consequence is that background levels of radio-frequency radiation

  16. RFID Transponders' Radio Frequency Emissions in Aircraft Communication and Navigation Radio Bands

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Ely, Jay J.; Williams, Reuben A.; Koppen, Sandra V.; Salud, Maria Theresa P.

    2006-01-01

    Radiated emissions in aircraft communication and navigation bands are measured from several active radio frequency identification (RFID) tags. The individual tags are different in design and operations. They may also operate in different frequency bands. The process for measuring the emissions is discussed, and includes tag interrogation, reverberation chamber testing, and instrument settings selection. The measurement results are described and compared against aircraft emission limits. In addition, interference path loss for the cargo bays of passenger aircraft is measured. Cargo bay path loss is more appropriate for RFID tags than passenger cabin path loss. The path loss data are reported for several aircraft radio systems on a Boeing 747 and an Airbus A320.

  17. High-temperature superconducting multi-band radio-frequency metamaterial atoms

    E-print Network

    Anlage, Steven

    High-temperature superconducting multi-band radio-frequency metamaterial atoms Behnood G. Ghamsari spectrum from radio-frequency (RF) up to visible and ultra- violet wavelengths. Nevertheless, at the low-frequency-fabricated compact high-temperature superconducting (HTS) metamaterial atom operating at a frequency as low as $53

  18. Comparative Study of Frequency Agile Data Transmission Schemes for Cognitive Radio Transceivers

    E-print Network

    Kansas, University of

    Comparative Study of Frequency Agile Data Transmission Schemes for Cognitive Radio Transceivers agile data transmission schemes employed by cognitive radio transceivers for use in dynamic spectrum requirements and conditions1 are known as cognitive radios [4]. With re- cent developments in cognitive radio

  19. Low-power CMOS radio frequency integrated circuits for frequency synthesis

    Microsoft Academic Search

    Rizwan Murji

    2005-01-01

    With the minimum feature size in microelectronic devices reducing to deep submicron values, complementary metal-oxide semiconductor (CMOS) technology has become a viable choice for implementation of radio frequency (RF) integrated circuit (IC) building blocks. In addition, portable devices are required to operate for extended periods of time without the need to charge or change the battery, highlighting the importance of

  20. Physical properties of conventional explosives deduced from radio frequency emissions

    SciTech Connect

    Harlin, Jeremiah D [Los Alamos National Laboratory; Nemzek, Robert [Los Alamos National Laboratory

    2008-01-01

    Los Alamos National Laboratory collected broadband radio frequency (RF) electric field change measurements from multiple detonations of high explosives (HE). Three types of HE were used: small cylinders of flake TNT, solid TNT, and PBX-9501. Low frequency signals (<80 MHz) were shot-to-shot repeatable and occurred within the first 100 {mu} s at measured amplitudes of about 2 V m{sup -1} at 35 m distance. High frequency signals (>290 MHz) occurred later, were an order of magnitude lower in signal strength, and were not repeatable. There is a positive correlation between the maximum electric field change and the shock velocity of the HE. The amount of free charge produced in the explosion estimated from the first RF pulse is between 10 and 150 {mu} C. This implies a weakly ionized plasma with temperatures between 2600 and 2900 K.

  1. Ross Ice Shelf in situ radio-frequency ice attenuation

    E-print Network

    Taylor Barrella; Steven Barwick; David Saltzberg

    2012-05-01

    We have measured the in situ average electric field attenuation length for radio-frequency signals broadcast vertically through the Ross Ice Shelf. We chose a location, Moore Embayment, south of Minna Bluff, known for its high reflectivity at the ice-sea interface. We confirmed specular reflection and used the return pulses to measure the average attenuation length from 75-1250 MHz over the round-trip distance of 1155 m. We find the average electric field attenuation length to vary from 500 m at 75 MHz to 300 m at 1250 MHz, with an experimental uncertainty of 55 to 15 m. We discuss the implications for neutrino telescopes that use the radio technique and include the Ross Ice Shelf as part of their sensitive volume.

  2. Ross Ice Shelf in situ radio-frequency ice attenuation

    E-print Network

    Barrella, Taylor; Saltzberg, David

    2010-01-01

    We have measured the in situ average electric field attenuation length for radio-frequency signals broadcast vertically through the Ross Ice Shelf. We chose a location, Moore Embayment, south of Minna Bluff, known for its high reflectivity at the ice-sea interface. We confirmed specular reflection and used the return pulses to measure the average attenuation length from 75-1250 MHz over the round-trip distance of 1155 m. We find the average electric field attenuation length to vary from 500 m at 75 MHz to 300 m at 1250 MHz, with an experimental uncertainty of 55 to 15 m. We discuss the implications for neutrino telescopes that use the radio technique and include the Ross Ice Shelf as part of their sensitive volume.

  3. Linear polarization of molecular lines at radio frequencies

    NASA Astrophysics Data System (ADS)

    Deguchi, S.; Watson, W. D.

    1984-10-01

    Calculations of the linear polarization of molecular emission lines from interstellar clouds at radio frequencies are extended by taking into account several coupled rotational states of a diatomic molecule. The goal of the calculations is to provide improved predictions of polarization with which to evaluate the observational results of Wannier, Scoville, and Barvainis (1983). It is found that the inclusion of additional states tends to decrease the maximum polarizations by a factor of about 2, except during superthermal excitation. The maximum polarizations obtained for the J = 2 to 1 transition tend to be somewhat less than those for J = 1 to 0. The polarization effects for a single-dish radio telescope are also estimated.

  4. Microelectromechanical system radio frequency switches in a picosatellite mission

    NASA Astrophysics Data System (ADS)

    Yao, J. Jason; Chien, Charles; Mihailovich, Robert; Panov, Viktor; DeNatale, Jeffrey; Studer, Judy; Li, Xiaobin; Wang, Anhua; Park, Sangtae

    2001-12-01

    Rockwell Science Center (RSC) has designed and implemented a microelectromechanical-system- (MEMS-) based radio frequency switch experiment in a miniature satellite format (picosat) as an initial demonstration of MEMS for space applications. This effort is supported by DARPA-MTO, and the mission was conducted with Aerospace Corporation and Stanford University as partners. MEMS surface-micromachined metal contacting switches were manufactured and used in a simple, yet informative, experiment aboard the miniature satellites to study the device behavior in space, and its feasibility for space applications in general. Communication links between multiple miniature satellites, as well as between the satellites and ground, were also achieved using communications circuits constructed and provided by RSC. Details of both the MEMS and radio communications and networking efforts will be discussed in this paper.

  5. Radio Frequency and Microwave Hazards Radio frequency (rf) and microwaves occur within the range 10 kHz to 300,000 MHz and are

    E-print Network

    Shull, Kenneth R.

    Radio Frequency and Microwave Hazards Radio frequency (rf) and microwaves occur within the range 10. Extreme overexposure to microwaves can result in the development of cataracts or sterility or both microwaved. If the sterility of the contents must be preserved, screw caps may be replaced with cotton

  6. Frequency Division Multiplexed Radio-over-Fiber Transmission using an Optically Injected Laser Diode

    E-print Network

    Chan, Sze-Chun

    Frequency Division Multiplexed Radio-over-Fiber Transmission using an Optically Injected Laser: Nonlinear dynamics, optical injection, frequency division multiplexing (FDM), radio-over-fiber (Ro for application as a photonic microwave source in radio-over-fiber (RoF) systems. It is advantageous over

  7. Sensitivity of the Kurtosis Statistic as a Detector of Pulsed Sinusoidal Radio Frequency Interference in a

    E-print Network

    Ruf, Christopher

    Sensitivity of the Kurtosis Statistic as a Detector of Pulsed Sinusoidal Radio Frequency@umich.edu Abstract--Radio frequency interference (RFI) from anthropogenic sources in microwave radiometers detecting-Detectors, digital radio, interference suppression, microwave radiometry. I. INTRODUCTION The kurtosis statistic

  8. Vandermonde-subspace Frequency Division Multiplexing for Two-Tiered Cognitive Radio

    E-print Network

    Paris-Sud XI, Université de

    Vandermonde-subspace Frequency Division Multiplexing for Two-Tiered Cognitive Radio Networks--Vandermonde-subspace frequency division multi- plexing (VFDM) is an overlay spectrum sharing technique for cognitive radio. VFDM/Hz over cognitive radio systems based on unused band detection. We also present some key design parameters

  9. Using a Satellite Swarm for building a Space-based Radio Telescope for Low Frequencies

    Microsoft Academic Search

    Mark Bentum; A. J. Boonstra; C. J. M. Verhoeven; A. J. van der Veen; E. K. A. Gill; N. Saks; H. Falcke; M. Klein-Wolt; R. T. Rajan; S. J. Wijnholds; M. Arts; K. van't Klooster; F. Beliün; A. Meijerink; B. Monna; J. Rotteveel; M. A. Boer; E. Bongers; E. Boom; E. van Tuijl; A. van Staveren

    2010-01-01

    In radio astronomy, as in astronomy in general, a wide range of frequencies is observed as each spectral band offers a unique window to study astrophysical phenomena. In the recent years, new observatories have been designed and built at the extreme limits of the radio spectrum. For the low frequencies several Earth-based radio telescopes are constructed at this moment. In

  10. An Evolutionary Approach for Frequency Assignment in Cellular Radio Networks \\Lambda

    E-print Network

    Hao, Jin-Kao

    An Evolutionary Approach for Frequency Assignment in Cellular Radio Networks \\Lambda Rapha¨el Dorne The Frequency Assignment Problem (FAP) in Cel­ lular Radio Networks is a very complex application in the field Assignment Problem (FAP) in Cellular Radio Networks. This problem is of great importance both in practice

  11. Cut-off Rate based Outage Probability Analysis of Frequency Hopping Mobile Radio under Jamming

    E-print Network

    Yýlmaz, Özgür

    Cut-off Rate based Outage Probability Analysis of Frequency Hopping Mobile Radio under Jamming hopping (FH) mobile radios under heavy jamming scenarios. With the use of outage probability analysis of radio frequency bursts (RFB) (or degrees of freedom) is determined in order to transmit a message

  12. Advanced techniques for enhancing wireless RF transmitters' power efficiency

    Microsoft Academic Search

    Slim Boumaiza

    2008-01-01

    This paper expounds on power efficiency enhancement techniques that are sought for the reduction of power consumption of wireless radio frequency power amplifiers (RFPA) and transmitters. The paper will focus on advanced power amplification architectures such as doherty power amplifiers (DPA), linear amplification using nonlinear components (LINC), envelop elimination and restoration (EER) and envelope tracking (ET) techniques. Overview on each

  13. Automatic calibration of modulated fractional-N frequency synthesizers

    E-print Network

    McMahill, Dan

    2001-01-01

    The focus of this research has been the development of a low power, radio frequency transmitter architecture. Specifically, a technique for in service automatic calibration of a modulated phase locked loop (PLL) frequency ...

  14. Passive radar in the high frequency band

    Microsoft Academic Search

    Giuseppe Fabrizio; Fabiola Colone; Pierfrancesco Lombardo; Alfonso Farina

    2008-01-01

    Passive radar systems using emitters of opportunity for target detection and tracking have received significant interest recently, especially those which exploit frequency modulated (FM) radio stations and TV transmitters as signal sources. This paper is concerned with passive radar systems that utilize signal sources in the high frequency (HF) band (3-30 MHz), where due to long-distance ionospheric propagation, the transmitter

  15. Design and characterization of a radio-frequency dc/dc power converter

    E-print Network

    Jackson, David A. (David Alexander)

    2005-01-01

    The use of radio-frequency (RF) amplifier topologies in dc/dc power converters allows the operating frequency to be increased by more than two orders of magnitude over the frequency of conventional converters. This enables ...

  16. CHARACTERIZATION OF K-BAND RADIO FREQUENCY INTERFERENCE FROM AMSR-E, WINDSAT AND SSM/I

    E-print Network

    Ruf, Christopher

    CHARACTERIZATION OF K-BAND RADIO FREQUENCY INTERFERENCE FROM AMSR-E, WINDSAT AND SSM/I Darren McKague, John J. Puckett and Christopher Ruf University of Michigan ABSTRACT An algorithm to detect radio-frequency, radio-frequency interference 1. INTRODUCTION Radio Frequency Interference (RFI) from human sources

  17. Resonant-frequency discharge in a multi-cell radio frequency cavity

    NASA Astrophysics Data System (ADS)

    Popovi?, S.; Upadhyay, J.; Mammosser, J.; Nikoli?, M.; Vuškovi?, L.

    2014-11-01

    We are reporting experimental results on a microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency cryo-module. This discharge offers a mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the issues related to resonant detuning due to sustained multi-cell cavity plasma. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

  18. Jupiter's low-frequency radio spectrum from Cassini\\/Radio and Plasma Wave Science (RPWS) absolute flux density measurements

    Microsoft Academic Search

    P. Zarka; B. Cecconi; W. S. Kurth

    2004-01-01

    We apply the calibration method developed by Dulk et al. [2001] to the data from the Cassini\\/Radio and Plasma Wave Science (RPWS) High-Frequency Receiver in order to derive flux density measurements of six components of the Jovian low-frequency radio spectrum over the full frequency range of the instrument (3.5 kHz to 16.1 MHz). The estimated accuracy is better than 50%,

  19. Radio-frequency quadrupole: general properties and specific applications

    SciTech Connect

    Stokes, R.H.; Crandall, K.R.; Hamm, R.W.

    1980-01-01

    The radio-frequency quadrupole (RFQ) linac structure is being developed for the acceleration of low-velocity ions. Recent experimental tests have confirmed its expected performance and have led to an increased interest in a wide range of possible applications. The general properties of RFQ accelerators are reviewed and beam dynamics simulation results are presented for their use in a variety of accelerating systems. These include the low-beta sections of the Fusion Materials Irradiation Test Accelerator, a 200-MHz proton linear accelerator, and a xenon accelerator for heavy ion fusion.

  20. Plasma plume propagation characteristics of pulsed radio frequency plasma jet

    SciTech Connect

    Liu, J. H.; Liu, X. Y.; Hu, K.; Liu, D. W.; Lu, X. P. [Advanced Electromagnetic Engineering and Technology Laboratory, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2011-04-11

    A 4 cm long helium cold atmospheric pressure plasma jet with pulsed radio frequency (rf) excitation was obtained by a copper electrode inside a quartz tube. The plasma bullet propagation characteristics common to the microseconds direct current pulse and kilohertz plasma jet is not observed in this case. The space-, time-, and wavelength-resolved optical emission profiles suggest the pulsed rf plasma channel out of the tube was strengthened by ions and metastables with longer life time than the rf period, and the plasma propagation was actually an illumination of the plasma channel caused by energetic electrons accelerated along the channel.

  1. Plasma plume propagation characteristics of pulsed radio frequency plasma jet

    NASA Astrophysics Data System (ADS)

    Liu, J. H.; Liu, X. Y.; Hu, K.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2011-04-01

    A 4 cm long helium cold atmospheric pressure plasma jet with pulsed radio frequency (rf) excitation was obtained by a copper electrode inside a quartz tube. The plasma bullet propagation characteristics common to the microseconds direct current pulse and kilohertz plasma jet is not observed in this case. The space-, time-, and wavelength-resolved optical emission profiles suggest the pulsed rf plasma channel out of the tube was strengthened by ions and metastables with longer life time than the rf period, and the plasma propagation was actually an illumination of the plasma channel caused by energetic electrons accelerated along the channel.

  2. Radio Frequency Identification (RFID) in healthcare: a literature review.

    PubMed

    Kolokathi, Aikaterini; Rallis, Panagiotis

    2013-01-01

    Creating and maintaining a safe and high-quality health care environment is of great importance for global community. New technologies and their applications can help us achieve this goal. Radio-Frequency Identification (RIFD) technology is considered one of those technologies and even today there are some interesting deployments in the health industry. As a result, this work aims to present the basic idea behind RFID solutions, problems that can be addressed with the adoption of RFID and the benefits of relative applications. PMID:23823408

  3. Silicon nanowire based radio-frequency spectrum analyzer.

    PubMed

    Corcoran, Bill; Vo, Trung D; Pelusi, Mark D; Monat, Christelle; Xu, Dan-Xia; Densmore, Adam; Ma, Rubin; Janz, Siegfried; Moss, David J; Eggleton, Benjamin J

    2010-09-13

    We demonstrate a terahertz bandwidth silicon nanowire based radio-frequency spectrum analyzer using cross-phase modulation. We show that the device provides accurate characterization of 640Gbaud on-off-keyed data stream and demonstrate its potential for optical time-division multiplexing optimization and optical performance monitoring of ultrahigh speed signals on a silicon chip. We analyze the impact of free carrier effects on our device, and find that the efficiency of the device is not reduced by two-photon or free-carrier absorption, nor its accuracy compromised by free-carrier cross-chirp. PMID:20940910

  4. Nonlinear frequency coupling in dual radio-frequency driven atmospheric pressure plasmas

    SciTech Connect

    Waskoenig, J.; Gans, T. [Centre for Plasma Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2010-05-03

    Plasma ionization, and associated mode transitions, in dual radio-frequency driven atmospheric pressure plasmas are governed through nonlinear frequency coupling in the dynamics of the plasma boundary sheath. Ionization in low-power mode is determined by the nonlinear coupling of electron heating and the momentary local plasma density. Ionization in high-power mode is driven by electron avalanches during phases of transient high electric fields within the boundary sheath. The transition between these distinctly different modes is controlled by the total voltage of both frequency components.

  5. Low Frequency Radio Signal Polarisation Sensor with Applications in Attitude Estimation

    E-print Network

    Maguire, Sean; Robertson, Paul

    2014-01-01

    A novel system for estimating the attitude (orientation) of a platform using measurements of Low Frequency (LF) radio signals is reported. The sensor system consists of an array of three orthogonal solenoid coil antennas, a three channel radio...

  6. Radar transmitter procedures

    NASA Astrophysics Data System (ADS)

    1993-03-01

    This ITOP outlines the test methods used in evaluating the performance and characteristics of general types of radar transmitters to include single or variable frequency transmitters. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. This ITOP is limited to methods for measuring the performance of the radar transmitter under test as a major component. Some performance aspects of the transmitter can be tested only when configured as part of a total radar system.

  7. A radio-frequency source using direct digital synthesis and field programmable gate array for nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Weimin, Wang

    2009-12-01

    A radio-frequency (rf) source for nuclear magnetic resonance (NMR) is described. With the application of direct digital synthesis (DDS), the rf source has the ability to yield rf pulses with short switching time and high resolution in frequency and phase. To facilitate the generation of a soft pulse, a field programmable gate array (FPGA) cooperating with a pulse programmer is used as the auxiliary controller of the DDS chip. Triggered by the pulse programmer, the FPGA automatically controls the DDS to generate soft pulse according to predefined parameters, and the operation mode of the pulse programmer is optimized. The rf source is suitable for being used as transmitter in low-field (<1 T) NMR applications, for example, magnetic resonance imaging and relaxation measurement. As a compact and low-cost module, the rf source is of general use for constructing low-field NMR spectrometer.

  8. High-resolution radio study of SNR IC443 at low radio frequencies

    E-print Network

    Castelletti, G; Clarke, T; Kassim, N E

    2011-01-01

    We investigated in detail the morphology at low radio frequencies of the supernova remnant IC443 and accurately established its radio continuum spectral properties. We used the VLA in multiple configurations to produce high resolution radio images of IC443 at 74 and 330 MHz. The changes with position in the radio spectral index were correlated with data in near infrared from 2MASS, in gamma-rays from VERITAS, and with the molecular 12^CO line emission. The new image at 74 MHz has HPBW=35", rms=30 mJy/beam and at 330 MHz HPBW= 17" and rms=1.7 mJy/beam. The integrated flux densities for the whole SNR are S_74MHz=470+/-51 Jy and S_330MHz=248+/-15 Jy. For the pulsar wind nebula associated with the compact source CXOUJ061705.3+222127, we calculated S_330MHz=0.23+/-0.05 Jy, S_1420MHz=0.20+/-0.04 Jy, and alpha~0.0. Substantial variations are observed in spectral index between 74 and 330 MHz across IC443. The flattest spectral components (-0.25< alpha<-0.05) coincide with the brightest parts of the SNR along th...

  9. Simultaneous occupational exposure to FM and UHF transmitters.

    PubMed

    Vali?, Blaž; Kos, Bor; Gajšek, Peter

    2012-01-01

    Occupational exposure caused by large broadcasting transmitters exceeds current reference levels. As it is common for different radio and TV transmitters to share the location, we analysed combined exposure on a 40-m high mast. The frequency modulation (FM) transmitter, located between the 10th and 30th metre, had the power of 25 kW, whereas an ultra-high frequency (UHF) transmitter of 5 kW occupied the top 8 m of the mast. Measured and calculated values of the electric field strength exceeded the reference levels up to 10 times; however, the results for the specific absorption rate (SAR) values show that the reference levels are very conservative for FM exposure, i.e., basic restrictions are not exceeded even when the reference levels are exceeded 10 times. However, for UHF exposure the reference levels are not conservative; they give a good prediction of real exposure. PMID:22721535

  10. Humeral remodeling and soft tissue injury of the wings caused by backpack harnesses for radio transmitters in New Zealand Takah? (Porphyrio hochstetteri).

    PubMed

    Michael, Sarah; Gartrell, Brett; Hunter, Stuart

    2013-07-01

    Backpack harnesses are commonly used to attach radio and satellite transmitters to a wide range of bird species for research and conservation management. They are an integral part of the conservation management of the New Zealand Takah? (Porphyrio hochstetteri), an endangered flightless rail. Radio transmitters mounted on backpack harnesses enable the birds to be tracked in their remaining native range of remote, mountainous Fiordland, New Zealand. We evaluated 26 Takah? retrospectively at necropsy by gross examination, radiography, and computed tomography to assess damage from the backpack harness. Ten birds that had never worn a harness had no evidence of wing injury. Of the 16 birds that had worn a harness, 10 (63%) had superficial soft tissue injury to skin or patagium or more severe injury, such as remodeling of the distal humerus at the harness cord-wing interface, or pathologic fractures. Such injuries are hypothesized to be associated with discomfort, increased risk of infection or fracture, and therefore reduced fitness. These findings have implications for all avian species deployed with backpack harnesses. PMID:23778604

  11. Abstract --This paper presents the world's first fundamental frequency CMOS 210GHz transceiver. The transmitter (TX)

    E-print Network

    Heydari, Payam

    exhibits a measured in-band gain of 18dB and minimum in- band noise figure (NF) of 11dB. The TX achieves-wave/THz frequency range unfolds new ideas on super-precise sensing at micrometer-level and multi-10-gigabit instant

  12. Solar radio emission very near the plasma frequency

    SciTech Connect

    Wentzel, D.G.

    1983-07-01

    Plasma-frequency radio emission from the solar corona has been observed with very short duration and very narrow bandwidth. These observations imply an upper corona with a structured field-aligned density distribution. I evaluate the propagation characteristics of fundamental plasma radio emission when the bandwidth is small compared with the electron gyrofrequency (..cap omega..), which is small compared with the plasma frequency (..omega../sub p/). The ''normal'' group velocity, c(..cap omega../..omega../sub p/)/sup 1//sup ///sup 2/, applies only to radiation emitted nearly parallel to the magnetic field. Most of the radiation at first travels with a much lower group velocity and is delayed relative to the radiation emitted parallel to the magnetic field. Radiation emitted at one instant of time over a finite range of angles leaves the corona with a time profile of finite duration. Very short observed signals of about 20 ms duration may be explained in two ways. (1) We observe only rays from a small part of the cone of emission. Then the observed bandwidth may be small compared with the inherent bandwidth of emission. (2) The density scale height is substantially less than 10/sup 5/ km, and the direction of the density gradient is well outside the cone of emission. The shortest signals from the upper corona may indicate density variations across magnetic flux tubes with scale heights as small as 10/sup 4/ km.

  13. Stochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a)

    E-print Network

    Kaganovich, Igor

    Stochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a) V. I. Kolobov is governed by three frequencies: the frequency of the rf field , the collision frequency , and the bounce frequency . Depending on the ratio between these frequencies, different electron dynamics and a variety

  14. Anomalous Capacitive Sheath with Deep Radio-Frequency Electric-Field Penetration Igor D. Kaganovich

    E-print Network

    Kaganovich, Igor

    Anomalous Capacitive Sheath with Deep Radio-Frequency Electric-Field Penetration Igor D. Kaganovich; published 10 December 2002) A novel nonlinear effect of anomalously deep penetration of an external radio-frequency of the region is of order VT=!, where VT is the electron thermal velocity, and ! is the frequency

  15. Radio frequency electrical transduction of graphene mechanical resonators Yuehang Xu,1,2

    E-print Network

    Kim, Philip

    Radio frequency electrical transduction of graphene mechanical resonators Yuehang Xu,1,2 Changyao 2010; published online 17 December 2010 We report radio frequency rf electrical readout of graphene with resonant frequency 34 MHz, quality factor 10 000 at 77 K, and signal-to-background ratio of over 20 d

  16. Effect of radio frequency discharge power on dusty plasma parameters

    SciTech Connect

    Sheridan, T. E. [Department of Physics and Astronomy, Ohio Northern University, Ada, Ohio 45810 (United States)

    2009-08-01

    The parameters of a two-dimensional dusty plasma consisting of six, 9 mum diameter particles trapped inside a radio frequency (rf) plasma sheath have been measured as a function of rf power in a 13.5 mtorr (1.8 Pa) argon discharge. The center-of-mass and breathing frequencies are found by projecting the cluster's Brownian motion onto the associated normal mode. The center-of-mass frequency (i.e., radial confinement) is insensitive to rf power. The Debye shielding parameter kappa, as found from the breathing frequency, increases from approx =0.5 to 2 as the square root of rf power. The Debye length decreases from approx =2.7 to 0.7 mm as the inverse of the square root of rf power. The average particle charge qapprox =-17 000e is effectively independent of rf power. These results are consistent with an electron temperature that is independent of rf power and an ion density that is directly proportional to rf power, where the Debye length is determined by the ion density in combination with the electron temperature.

  17. Evaporative cooling in a radio-frequency trap

    SciTech Connect

    Garrido Alzar, Carlos L.; Perrin, Helene; Lorent, Vincent [Laboratoire de Physique des Lasers, CNRS-Universite Paris 13, Villetaneuse (France); Garraway, Barry M. [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)

    2006-11-15

    A theoretical investigation for implementing a scheme of forced evaporative cooling in radio-frequency (rf) adiabatic potentials is presented. Supposing the atoms to be trapped in a combination of a dc magnetic field and a rf field at frequency {omega}{sub 1}, the cooling procedure is facilitated using a second rf source at frequency {omega}{sub 2}. This second rf field produces a controlled coupling between the spin states dressed by {omega}{sub 1}. The evaporation is then possible in a pulsed or continuous mode. In the pulsed case, atoms with a given energy are transferred into untrapped dressed states by abruptly switching off the {omega}{sub 2} coupling. In the continuous case, it is possible for energetic atoms to adiabatically follow the doubly dressed states and escape out of the trap. Our results also show that when {omega}{sub 1} and {omega}{sub 2} are separated by at least the Rabi frequency associated with {omega}{sub 1}, additional evaporation zones appear which can make this process more efficient.

  18. Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment

    Microsoft Academic Search

    C. E. Liekhus-Schmaltz; J. D. D. Martin

    2011-01-01

    We have developed a senior undergraduate experiment that illustrates frequency stabilization techniques using radio-frequency electronics. The primary objective is to frequency stabilize a voltage controlled oscillator to a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This technique is commonly applied to stabilize lasers at optical frequencies. By using only radio-frequency equipment it is possible to systematically study aspects

  19. Low Frequency Radio Observations of GRS1915+105 with GMRT

    E-print Network

    C. H. Ishwara-Chandra; A. Pramesh Rao; Mamta Pandey; R. K. Manchanda; Philippe Durouchoux

    2005-12-02

    We present the first detailed low frequency radio measurements of the galactic microquasar GRS1915+105 with GMRT. Simultaneous observations were carried out at 610 and 244 MHz. Our data does not show any signature of spectral turn over even at low radio frequency of 244 MHz. We propose that while the radio emission at high radio frequencies could predominantly come from compact jets, the emission at lower frequency originates in the lobes at the end of the jet which acts like a reservoir of low energy electrons.

  20. 47 CFR 2.803 - Marketing of radio frequency products prior to equipment authorization.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY...of the Federal Communications Commission...developers, and system integrators...and maximum power or field...

  1. 47 CFR 2.803 - Marketing of radio frequency devices prior to equipment authorization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY...of the Federal Communications Commission...developers, and system integrators...and maximum power or field...

  2. 78 FR 43916 - Certain Radio Frequency Identification (RFID) Products and Components Thereof; Commission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-22

    ...INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-875] Certain Radio Frequency Identification (RFID) Products and Components Thereof; Commission Determination Not To Review an Initial Determination Terminating...

  3. Effects of microwave and radio frequency electromagnetic fields on lichens.

    PubMed

    Urech, M; Eicher, B; Siegenthaler, J

    1996-01-01

    The effects of electromagnetic fields on lichens were investigated. Field experiments of long duration (1-3 years) were combined with laboratory experiments and theoretical considerations. Samples of the lichen species Parmelia tiliacea and Hypogymnia physodes were exposed to microwaves (2.45 GHz; 0.2, 5, and 50 mW/cm2; and control). Both species showed a substantially reduced growth rate at 50 mW/cm2. A differentiation between thermal and nonthermal effects was not possible. Temperature measurements on lichens exposed to microwaves (2.45 GHz, 50 mW/cm2) showed a substantial increase in the surface temperature and an accelerated drying process. The thermal effect of microwave on lichens was verified. The exposure of lichens of both species was repeated near a short-wave broadcast transmitter (9.5 MHz, amplitude modulated; maximum field strength 235 V/m, 332 mA/m). No visible effects on the exposed lichens were detected. At this frequency, no thermal effects were expected, and the experimental results support this hypothesis. Theoretical estimates based on climatic data and literature showed that the growth reductions in the initial experiments could very likely have been caused by drying of the lichens from the heating with microwaves. The results of the other experiments support the hypothesis that the response of the lichens exposed to microwaves was mainly due to thermal effects and that there is a low probability of nonthermal effects. PMID:8891192

  4. Burst coherent detection with robust frequency and timing estimation for portable radio communications

    Microsoft Academic Search

    Justin C-I Chuang; Nelson Sollenberger

    1988-01-01

    The authors describe two approaches that make burst coherent demodulation robust against frequency offset between transmitter and receiver: using a second-order PLL (phase lock loop) to track frequency error, and performing transforms between phase and rectangular vector components to eliminate errors caused by wraparound discontinuities. It is found that with a small increase in circuit complexity (mostly additional read-only memory),

  5. Interplanetary type 3 radio bursts that approach the plasma frequency: Ulysses observations

    NASA Technical Reports Server (NTRS)

    Hoang, S.; Dulk, G. A.; Leblanc, Y.

    1994-01-01

    We study a set of solar type 3 radio bursts where the emission is visible from the high-frequency limit of the radio astronomy receiver of the Ulysses Unified Radio and Plasma wave (URAP) experiment down to low frequencies, sometimes near the plasma frequency, and where Langmuir wave spikes are recorded by the radio and/or plasma receivers. Our results pose questions regarding radio emission by Langmuir waves. When Langmuir waves are observed, why is it only sometimes that radio radiation is emitted at the fundamental? Put another way, why is there often a gap or a cutoff in the radiation at a frequency well above the plasma frequency? In the few cases where the radiation at times of Langmuir wave spikes is at the harmonic, why is there no fundamental?

  6. Hybrid radio-intermediate-frequency oscillator with photonic-delay-matched frequency conversion pair.

    PubMed

    Dai, Yitang; Wang, Ruixin; Yin, Feifei; Dai, Jian; Zhou, Yue; Li, Jianqiang; Xu, Kun

    2015-06-15

    A low-phase-noise, single-loop radio-frequency (RF) oscillator is proposed and experimentally demonstrated where part of the oscillation is in intermediate-frequency (IF) domain by a pair of frequency conversions. Single-mode operation is achieved by IF filtering. The key design is the matched photonic delay between the two conversions, by which the large phase noise of the common external RF local oscillation (LO) shows no impact on the RF carrier passing through the conversion pair and the low-phase-noise oscillation is guaranteed. The phase-noise performance of the delay-matched conversion pair plus IF filtering is theoretically and experimentally studied. With the proposed scheme, we achieve 120 dBc/Hz phase noise at 10-kHz offset from 10-GHz carrier frequency through a 1-?s loop cavity. PMID:26076289

  7. Radio-frequency superimposed direct current magnetron sputtered Ga:ZnO transparent conducting thin films

    NASA Astrophysics Data System (ADS)

    Sigdel, Ajaya K.; Ndione, Paul F.; Perkins, John D.; Gennett, Thomas; van Hest, Maikel F. A. M.; Shaheen, Sean E.; Ginley, David S.; Berry, Joseph J.

    2012-05-01

    The utilization of radio-frequency (RF) superimposed direct-current (DC) magnetron sputtering deposition on the properties of gallium doped ZnO (GZO) based transparent conducting oxides has been examined. The GZO films were deposited using 76.2 mm diameter ZnO:Ga2O3 (5 at. % Ga vs. Zn) ceramic oxide target on heated non-alkaline glass substrates by varying total power from 60 W to 120 W in steps of 20 W and at various power ratios of RF to DC changing from 0 to 1 in steps of 0.25. The GZO thin films grown with pure DC, mixed approach, and pure RF resulted in conductivities of 2200 ± 200 S/cm, 3920 ± 600 S/cm, and 3610 ± 400 S/cm, respectively. X-ray diffraction showed all films have wurtzite ZnO structure with the c-axis oriented perpendicular to the substrate. The films grown with increasing RF portion of the total power resulted in the improvement of crystallographic texture with smaller full-width half maximum in ? and broadening of optical gap with increased carrier concentration via more efficient doping. Independent of the total sputtering power, all films grown with 50% or higher RF power portion resulted in high mobility (˜28 ± 1 cm2/Vs), consistent with observed improvements in crystallographic texture. All films showed optical transmittance of ˜90% in the visible range.

  8. Glass-based confined structures fabricated by sol-gel and radio frequency sputtering

    NASA Astrophysics Data System (ADS)

    Chiappini, Andrea; Armellini, Cristina; Carpentiero, Alessandro; Vasilchenko, Iustyna; Lukowiak, Anna; Risti?, Davor; Varas, Stefano; Normani, Simone; Mazzola, Maurizio; Chiasera, Alessandro

    2014-07-01

    Some of the main results obtained in the field of glass-based photonic crystal (PC) systems using complementary techniques, such as radio frequency (RF) sputtering and sol-gel route, are presented. Initially, rare earth-activated one-dimensional PCs fabricated by RF-sputtering technique will be discussed, specifically the cavity is constituted by an Er-doped SiO active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO2/TiO2 layers. Moreover, from near infrared, transmittance and variable angle reflectance spectra have verified the presence of a stop band from 1500 to 2000 nm with a cavity resonance centered at 1749 nm at 0 deg and quality factor of 890. In the second case, a composite system based on polystyrene colloidal nanoparticles assembled and embedded in an elastomeric matrix will be presented in detail. This system has been designed as a structure that displays an iridescent green color that can be attributed to the PC effect. This feature has been exploited to create a chemical sensor; in fact optical measurements have evidenced that this system presents a different optical response as a function of the solvent applied on the surface, showing: (1) high sensitivity, (2) fast response, and (3) reversibility of the signal change.

  9. Radio-Frequency Superimposed Direct Current Magnetron Sputtered Ga:ZnO Transparent Conducting Thin Films

    SciTech Connect

    Sigdel, A. K.; Ndione, P. F.; Perkins, J. D.; Gennett, T.; van Hest, M. F. A. M.; Shaheen, S. E.; Ginley, D. S.; Berry, J. J.

    2012-05-01

    The utilization of radio-frequency (RF) superimposed direct-current (DC) magnetron sputtering deposition on the properties of gallium doped ZnO (GZO) based transparent conducting oxides has been examined. The GZO films were deposited using 76.2 mm diameter ZnO:Ga{sub 2}O{sub 3} (5 at. % Ga vs. Zn) ceramic oxide target on heated non-alkaline glass substrates by varying total power from 60 W to 120 W in steps of 20 W and at various power ratios of RF to DC changing from 0 to 1 in steps of 0.25. The GZO thin films grown with pure DC, mixed approach, and pure RF resulted in conductivities of 2200 {+-} 200 S/cm, 3920 {+-} 600 S/cm, and 3610 {+-} 400 S/cm, respectively. X-ray diffraction showed all films have wurtzite ZnO structure with the c-axis oriented perpendicular to the substrate. The films grown with increasing RF portion of the total power resulted in the improvement of crystallographic texture with smaller full-width half maximum in {chi} and broadening of optical gap with increased carrier concentration via more efficient doping. Independent of the total sputtering power, all films grown with 50% or higher RF power portion resulted in high mobility ({approx}28 {+-} 1 cm{sup 2}/Vs), consistent with observed improvements in crystallographic texture. All films showed optical transmittance of {approx}90% in the visible range.

  10. Radio-frequency superimposed direct current magnetron sputtered Ga:ZnO transparent conducting thin films

    SciTech Connect

    Sigdel, Ajaya K.; Shaheen, Sean E. [Department of Physics and Astronomy, University of Denver, Denver, Colorado 80208 (United States); National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Ndione, Paul F.; Perkins, John D.; Gennett, Thomas; Hest, Maikel F. A. M. van; Ginley, David S.; Berry, Joseph J. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2012-05-01

    The utilization of radio-frequency (RF) superimposed direct-current (DC) magnetron sputtering deposition on the properties of gallium doped ZnO (GZO) based transparent conducting oxides has been examined. The GZO films were deposited using 76.2 mm diameter ZnO:Ga{sub 2}O{sub 3} (5 at. % Ga vs. Zn) ceramic oxide target on heated non-alkaline glass substrates by varying total power from 60 W to 120 W in steps of 20 W and at various power ratios of RF to DC changing from 0 to 1 in steps of 0.25. The GZO thin films grown with pure DC, mixed approach, and pure RF resulted in conductivities of 2200 {+-} 200 S/cm, 3920 {+-} 600 S/cm, and 3610 {+-} 400 S/cm, respectively. X-ray diffraction showed all films have wurtzite ZnO structure with the c-axis oriented perpendicular to the substrate. The films grown with increasing RF portion of the total power resulted in the improvement of crystallographic texture with smaller full-width half maximum in {chi} and broadening of optical gap with increased carrier concentration via more efficient doping. Independent of the total sputtering power, all films grown with 50% or higher RF power portion resulted in high mobility ({approx}28 {+-} 1 cm{sup 2}/Vs), consistent with observed improvements in crystallographic texture. All films showed optical transmittance of {approx}90% in the visible range.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  12. Isotropization of the terrestrial low-frequency radio bursts

    NASA Astrophysics Data System (ADS)

    Steinberg, J.-L.; Lacombe, C.; Hoang, S.

    2000-09-01

    We analyze ISEE 3 radio data acquired in the solar wind. Using a new technique we measure the spectrum of the isotropic component ("tail" or isotropic terrestrial kilometric radiation (ITKR)) of low-frequency (LF) bursts which extends from ? fp.sw (the interplanetary (IP) medium plasma frequency) to an upper limit fmax which can reach 5×fp.sw. The relative intensities of the auroral kilometric radiation (AKR) burst, often associated with LF bursts, and of the ITKR are highly variable when observed from the Lagrange point Ll most probably because of propagation effects. In the range of frequencies 2fp.sw < f < 5fp.sw the AKR source angular radius measured from Ll is a few degrees, while that of the ITKR source is close to 90°: the radiation from these two sources must propagate through very different regions of the magneto sphere. The isotropization of the radiation from a magnetospheric source at fmax requires the presence of large overdense structures in the IP medium. For each event, such structures were identified and their peak plasma frequency fp.bump measured using ISEE 3 plasma density data acquired in the ecliptic. The frequency fmax is always larger than fp.bump and there is only a weak correlation between these quantities. Thus fp.bump cannot be taken as a characteristic of the three-dimensional IP structures needed to isotropize the radiation. These structures should be rough and capable of sending some radiation towards the Sun to reach IP regions where higher values of fp.sw will be encountered. The study of the isotropization of LF bursts requires a deeper knowledge of the dense structures of the IP medium.

  13. Design, development, and acceleration trials of radio-frequency quadrupole

    NASA Astrophysics Data System (ADS)

    Rao, S. V. L. S.; Jain, Piyush; Pande, Rajni; Roy, Shweta; Mathew, Jose V.; Kumar, Rajesh; Pande, Manjiri; Krishnagopal, S.; Gupta, S. K.; Singh, P.

    2014-04-01

    A deuteron radio frequency quadrupole (RFQ) accelerator has been designed, fabricated, and tested at BARC, which will be used for neutron generation. The RFQ operates at a frequency of 350 MHz and needs an inter-vane voltage of 44 kV to accelerate the deuteron beam to 400 keV within a length of 1.03 m. The error analysis shows that the offset of two opposite vanes in the same direction by 100 ?m leads to a change in resonant frequency by 1.3 MHz and a significant change of fields in the quadrants (˜±40% with respect to average field). From the 3D analysis, we have observed that the unwanted dipole mode frequencies are very near to the quadrupole mode frequency which will make structure sensitive to the perturbations. In order to move the dipole modes away from the quadrupole modes, we have used the dipole stabilizer rods. The 5 wire transmission line theory was used to study the perturbative analysis of the RFQ and based on this a computer program has been written to tune the cavity to get required field distribution. Based on these studies, a 1.03 m long RFQ made of OFE copper has been fabricated and tested. Even though the RFQ was designed for deuteron (D+) beam, we tested it by accelerating both the proton (H+) and D+ beams. The RFQ was operated in pulsed mode and accelerated both H+ and D+ beams to designed values of 200 and 400 keV, respectively. The measured parameters are in good agreement with the designed values validating our simulations and fabrication processes. In this paper, simulations, RF measurements, and beam commissioning results are presented.

  14. Technologies for Low Frequency Radio Observations of the Cosmic Dawn

    NASA Technical Reports Server (NTRS)

    Jones, Dayton L.

    2014-01-01

    The Jet Propulsion Laboratory (JPL) is developing concepts and technologies for low frequency radio astronomy space missions aimed at observing highly redshifted neutral Hydrogen from the Dark Ages. This is the period of cosmic history between the recombination epoch when the microwave background radiation was produced and the re-ionization of the intergalactic medium by the first generation of stars (Cosmic Dawn). This period, at redshifts greater than about 20, is a critical epoch for the formation and evolution of large-scale structure in the universe. The 21-cm spectral line of Hydrogen provides the most promising method for directly studying the Dark Ages, but the corresponding frequencies at such large redshifts are only tens of MHz and thus require space-based observations to avoid terrestrial RFI and ionospheric absorption and refraction. This paper reports on the status of several low frequency technology development activities at JPL, including deployable bi-conical dipoles for a planned lunar-orbiting mission, and both rover-deployed and inflation-deployed long dipole antennas for use on the lunar surface.

  15. Radio frequency sheaths in an oblique magnetic field

    DOE PAGESBeta

    Myra, James R.; D'Ippolito, Daniel A.

    2015-06-01

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle ? with the surface. A set of one-dimensional equations is developed that describe the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle, ? assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numericallymore »to obtain the rectified (dc) voltage, the rf voltage across the sheath and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.« less

  16. Radio frequency sheaths in an oblique magnetic field

    NASA Astrophysics Data System (ADS)

    Myra, J. R.; D'Ippolito, D. A.

    2015-06-01

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle ? with the surface. A set of one-dimensional equations is developed that describes the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle ?, assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numerically to obtain the rectified (dc) voltage, the rf voltage across the sheath, and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general, the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.

  17. Military operations in urban terrain: indoor radio frequency propagation prediction methods

    Microsoft Academic Search

    Julia Andrusenko

    2004-01-01

    This paper investigates the applicability of two current military tactical communications technologies to military operations in urban terrain (MOUT): Single channel ground and airborne radio system (SINCGARS) and squad radios. Various existing radio frequency (RF) propagation prediction (or path loss) methods for urban environments were surveyed. The primary criterion for the selection of methods of consideration was that they must

  18. Using multiple beams to identify radio frequency interference in the search for extraterrestrial intelligence

    Microsoft Academic Search

    G. R. Harp

    2005-01-01

    The Allen Telescope Array (ATA) is a multiuser instrument and will perform simultaneous radio astronomy and radio search for extraterrestrial intelligence (SETI) observations. It is a multibeam instrument, with 16 independently steerable dual-polarization beams at four different tunings. Here we describe a new method for identifying radio frequency interference (RFI) that leverages the unique attributes of the ATA. Given four

  19. Stabilization of Fundamental-Frequency Microwave Oscillators for Radio-Relay Systems (Panel)

    Microsoft Academic Search

    F. Ivanek

    1978-01-01

    Frequency tolerances for microwave communications are presently under study within the International Telecommunications Union (ITU). This is being carried out in preparation for the World Administrative Radio Conference, 1979 (WAKC-79), which will revise the existing Radio Regulations. The International Radio Consultative Committee (CCIR) will hold in the Autumn of 1978, its Special Preparatory Meeting (SPM) for the WARC-79. So far,

  20. Low frequency turbulence in the solar corona and fundamental radiation of type III solar radio burst

    Microsoft Academic Search

    T. Takakura

    1979-01-01

    On the basis of the previous numerical simulations, a new mechanism for the emission of the fundamental radio waves of solar radio type III bursts is presented. This hypothesis is to attribute the fundamental radio emission to the coalescence of the plasma waves with the low frequency turbulence, whistler or ion acoustic waves, pre-existing on the way of the electron

  1. 1.8 GHz Radio Frequency signal radiation effects on human health

    Microsoft Academic Search

    Azizah Ahmad; Rusnani Ariffin; Norhayati Mohd Noor; Meor Adzmey Sagiruddin

    2011-01-01

    Radio Frequency (RF) radiation effects are strictly relying on few critical factors, ie frequency, period of exposure and distance. Certain frequency ranges are absorbed in body tissue more than the other frequency range. The second factor is the duration of exposure. Where, over the period of time, the body will absorb more RF frequencies which hence will worsened the human

  2. Electron beam diagnostics for a superconducting radio frequency photoelectron injector.

    PubMed

    Kamps, Thorsten; Arnold, Andre; Boehlick, Daniel; Dirsat, Marc; Klemz, Guido; Lipka, Dirk; Quast, Torsten; Rudolph, Jeniffa; Schenk, Mario; Staufenbiel, Friedrich; Teichert, Jochen; Will, Ingo

    2008-09-01

    A superconducting radio frequency (SRF) photoelectron injector is currently under construction by a collaboration of BESSY, DESY, FZD, and MBI. The project aims at the design and setup of a continuous-wave SRF injector including a diagnostics beamline for the ELBE free electron laser (FEL) and to address R&D issues on low emittance injectors for future light sources such as the BESSY FEL. Of critical importance for the injector performance is the control of the electron beam parameters. For this reason a compact diagnostics beamline is under development, serving a multitude of operation settings. In this paper the layout and the rationale of the diagnostics beamline are described. Furthermore detailed information on specific components is given, together with results from laboratory tests and data taking. PMID:19044401

  3. Radio frequency heating of ceramic windows in fusion applications

    NASA Astrophysics Data System (ADS)

    Fowler, J. D., Jr.

    1981-11-01

    Ceramic windows will be used as material barriers for radio frequency plasma heating in fusion reactors. This report examines the theory behind RF heating phenomena. Heating calculations are presented for various window materials, thicknesses, wavelengths, and power densities. The most pertinent material properties are loss tangent, thermal conductivity, dielectric constant, strength, and radiation resistance. Calculations indicate that among candidate materials, beryllium oxide offers the most promise because of its large thermal conductivity and relatively low loss tangent and dielectric constant. On the other hand, beryllia is susceptible to neutron damage, and this may adversely affect its electrical properties. Another promising candidate is sapphire, particularly at lower temperatures where the thermal conductivity is high. Fused silica suffers from low thermal conductivity and large positive temperature coefficient for loss tangent, but it may be useful under some conditions.

  4. Project 8: Using Radio Frequencies to Measure the Neutrino Mass

    E-print Network

    N. S. Oblath

    2011-10-10

    It is well known that the neutrino masses affect the shape of the energy spectrum of tritium beta-decay electrons. However, experiments have yet to measure that distortion. The Project 8 experiment proposes to measure the spectral distortion in a novel way: using radio-frequency techniques to detect and measure the energies of the beta-decay electrons. We plan on measuring the radiation created from the cyclotron motion of the electrons in a strong magnetic field. I will report on the status of a prototype that is designed to demonstrate single-electron detection at energies near the tritium endpoint, 18.6 keV. I will also discuss the possibilities for scaling up to a neutrino-mass experiment.

  5. Superconducting radio-frequency modules test faciilty operating experience

    SciTech Connect

    Soyars, W.; Bossert, R.; Darve, C.; Degraff, B.; Klebaner, A.; Martinez, A.; Pei, L.; Theilacker, J.; /Fermilab

    2007-07-01

    Fermilab is heavily engaged and making strong technical contributions to the superconducting radio-frequency research and development program (SRF R&D). Four major SRF test areas are being constructed to enable vertical and horizontal cavity testing, as well as cryomodule testing. The existing Fermilab cryogenic infrastructure has been modified to service Fermilab SRF R&D needs. The first stage of the project has been successfully completed, which allows for distribution of cryogens for a single cavity cryomodule using the existing Cryogenic Test Facility (CTF) that houses three Tevatron satellite refrigerators. The cooling capacity available for cryomodule testing at MDB results from the liquefaction capacity of the CTF cryogenic system. The cryogenic system for a single 9-cell cryomodule is currently operational. The paper describes the status, challenges and operational experience of the initial phase of the project.

  6. SUPERCONDUCTING RADIO-FREQUENCY MODULES TEST FACILITY OPERATING EXPERIENCE

    SciTech Connect

    Soyars, W.; Bossert, R.; Darve, C.; Degraff, B.; Klebaner, A.; Martinez, A.; Pei, L.; Theilacker, J. [Fermi National Accelerator Laboratory Batavia, IL, 60510 (United States)

    2008-03-16

    Fermilab is heavily engaged and making strong technical contributions to the superconducting radio-frequency research and development program (SRF R and D). Four major SRF test areas are being constructed to enable vertical and horizontal cavity testing, as well as cryomodule testing. The existing Fermilab cryogenic infrastructure has been modified to service the SRF R and D needs. The project's first stage has been successfully completed, which allows for distribution of cryogens for a single-cavity cryomodule using the existing Cryogenic Test Facility (CTF) that houses three Tevatron satellite refrigerators. The cooling capacity available for cryomodule testing at Meson Detector Building (MDB) results from the liquefaction capacity of the CTF cryogenic system. The cryogenic system for a single 9-cell cryomodule is currently operational. The paper describes the status, challenges and operational experience of the initial phase of the project.

  7. Radio frequency plasma mediated dry functionalization of multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Nair, Leena G.; Mahapatra, Anirban S.; Gomathi, N.; Joseph, K.; Neogi, S.; Nair, C. P. Reghunadan

    2015-06-01

    Surface modification of multiwall carbon nanotubes (MWCNT) was carried out by radio frequency (RF) plasma discharges of oxygen and nitrogen gases to improve their dispersibility. Various oxygen and nitrogen containing functional groups were incorporated as a result of plasma treatment and were confirmed through Fourier transform infrared spectroscopy (FTIR). The effect of plasma treatment on structural properties and morphology changes of MWCNTs was analyzed by Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The morphological studies indicate that untreated MWCNT exists as closely packed with highly entangled bundle. During the plasma treatment, MWCNT tubes get disentangled. XRD, Raman and TEM confirmed the absence of any surface damage during plasma treatment. Functionalized carbon nanotubes exhibit high zeta potential values indicating their good dispersibility in water. The method offers a direct and dry means for functionalization of MWCNT without affecting the structure of MWCNT.

  8. Nanocrystalline graphite films nucleation by the radio frequency bias pretreatment.

    PubMed

    Dvorkin, V V; Dzbanovsky, N N; Krivchenko, V A; Suetin, N V; Rakhimov, A T; Timofeyev, M A; Bespalov, A V; Golikova, O L

    2011-10-01

    New method for nucleation of different nanocrystalline carbon films upon monocrystalline Si substrate was proposed. The process is based on a combination of microwave and radio frequency plasma assisted chemical vapor deposition methods. Potential of the method for nucleation was demonstrated by deposition of nanocrystalline diamond film in pure microwave plasma in one process, immediately after "seeding" procedure. The method was also used for growth of nanocrystalline graphite (NCG) films, which are currently under intensive investigation due to their exceptional electronic properties, particularly fine electron emission characteristics. Deposited NCG films have demonstrated remarkable electron field emission properties having current density of up to 10 A/cm2. The films have also possessed good adhesion to silicon substrate. Carbon films and nucleation layer were characterized by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. PMID:22400280

  9. Geophysical subsurface probing with radio-frequency interferometry

    NASA Technical Reports Server (NTRS)

    Kong, J. A.; Tsang, L.; Simmons, G.

    1974-01-01

    The radio-frequency interferometry method can be used to probe interiors of celestial bodies and terrestrial areas with low conductivity. In order to interpret the interference patterns, a theoretical study is made of the electromagnetic fields due to a dipole antenna on the surface of a horizontally stratified n-layered medium. Three approaches are used to calculate the interference patterns: direct numerical integration, asymptotic evaluation by the saddle point method, and a residue series approach. The asymptotic approach leads to the geometrical-optics interpretation. The residue approach leads to modal analysis. The validity of the formulation is checked by comparisons with analog model tank experiments and actual field data obtained from glaciers.

  10. Fiducialization of Superconducting Radio Frequency Cryomodules at Jefferson Lab

    SciTech Connect

    C. J. Curtis; J. Dahlberg; W. Oren; J. Preble; K. Tremblay

    2006-09-26

    During the early 1990's the Continuous Electron Beam Accelerator Facility (CEBAF), was under construction in Newport News, Virginia. The facility was to be the first of its kind in that it was to provide a continuous beam of electrons for experimental physics at energies of several GeV. One of the key elements of this unique machine was the 338 superconducting radio frequency (SRF) cavities built into 42 cryomodules and arranged in two linacs. These were linked by arcs of conventional magnets which allowed recirculation through the linacs up to five times, in order to achieve the design energy of 4GeV. Within each cryomodule the cavities were aligned and referenced to external fiducials allowing alignment on the design beampath. This paper describes the process developed to achieve this, how it evolved with improving instrumentation, and the results obtained. Suggestions for alternative methods which may prove useful for future projects are also discussed.

  11. Reactivable passive radio-frequency identification temperature indicator

    NASA Astrophysics Data System (ADS)

    Windl, Roman; Bruckner, Florian; Abert, Claas; Suess, Dieter; Huber, Thomas; Vogler, Christoph; Satz, Armin

    2015-05-01

    A low cost, passive radio-frequency identification (RFID) temperature indicator with (re-) activation at any point of time is presented. The capability to detect a temperature excursion is realized by magnets and a solution with a melting point at the critical temperature. As the critical temperature is exceeded, a magnetic indicator switches to non-reversible and this can be monitored via a giant magnetoresistance sensor connected to a RFID tag. Depending on the solutions or metal alloys, detection of critical temperatures in a wide range from below 0 °C and up to more than 100 °C is possible. The information if a threshold temperature was exceeded (indicator state) as well as the identification number, current temperature, and user defined data can be obtained via RFID.

  12. Radio Frequency Single Electron Transistors on Si/SiGe

    NASA Astrophysics Data System (ADS)

    Yuan, Mingyun; Yang, Zhen; Rimberg, A. J.; Eriksson, M. A.; Savage, D. E.

    2011-03-01

    Superconducting single electron transistors (S-SETs) are ideal for charge state readout due to their high sensitivity and low back-action. Upon successful formation of quantum dots(QDs) on Si/SiGe, aluminum S-SETs are added in the vicinity of the QDs. Coupling of the S-SET to the QD is confirmed by using the S-SET to perform sensing of the QD charge state at 0.3 K. We have formed a matching network for an SET with an off-chip inductor. The reflection coefficient of the radio frequency(RF) signal is shown to be modulated by the SET resistance. Efforts to develop an on-chip matching network and perform charge sensing with the RF-SETs are in progress. Recent experimental results will be discussed. This research was supported by the NSA, LPS and ARO.

  13. Single-crystalline graphene radio-frequency nanoswitches

    NASA Astrophysics Data System (ADS)

    Li, Peng; Cui, Tianhong

    2015-07-01

    Growth of monolayer single-crystalline graphene (SCG) using the low-pressure chemical vapor deposition method is reported. Graphene’s superb quality and single-crystalline nature were characterized and verified by Raman microscopy, atomic force microscopy, and carrier mobility measurement. Radio-frequency (RF) nanoelectromechanical switches based on coplanar waveguide double-clamped SCG membrane were achieved, and the superb properties of SCG enable the switches to operate at a pull-in voltage as low as 1?V, with switch time in the nanosecond regime. Owing to their single-crystalline nature, the switches’ lifetime (>5000 times) is much longer than that of polycrystalline graphene ones reported. The RF devices exhibit good isolation (?30?dB at 40?GHz (Ka band)), which can be further improved by SCG’s conductivity variation due to actuation voltage.

  14. Ultrafast electron diffraction with radio-frequency compressed electron pulses

    SciTech Connect

    Chatelain, Robert P.; Morrison, Vance R.; Godbout, Chris; Siwick, Bradley J. [Departments of Physics and Chemistry, Center for the Physics of Materials, McGill University, Montreal (Canada)

    2012-08-20

    We report on the complete characterization of time resolution in an ultrafast electron diffraction (UED) instrument based on radio-frequency electron pulse compression. The temporal impulse response function of the instrument was determined directly in pump-probe geometry by performing electron-laser pulse cross-correlation measurements using the ponderomotive interaction. With optimal settings, a stable impulse response of 334{+-}10 fs was measured at a bunch charge of 0.1 pC (6.24 Multiplication-Sign 10{sup 5} electrons/pulse); a dramatic improvement compared to performance without pulse compression. Phase stability currently limits the impulse response of the UED diffractometer to the range of 334-500 fs, for bunch charges ranging between 0.1 and 0.6 pC.

  15. Numerical model study of radio frequency vessel sealing thermodynamics

    NASA Astrophysics Data System (ADS)

    Pearce, John

    2015-03-01

    Several clinically successful clinical radio frequency vessel-sealing devices are currently available. The dominant thermodynamic principles at work involve tissue water vaporization processes. It is necessary to thermally denature vessel collagen, elastin and their adherent proteins to achieve a successful fusion. Collagens denature at middle temperatures, between about 60 and 90 C depending on heating time and rate. Elastin, and its adherent proteins, are more thermally robust, and require temperatures in excess of the boiling point of water at atmospheric pressure to thermally fuse. Rapid boiling at low apposition pressures leads to steam vacuole formation, brittle tissue remnants and frequently to substantial disruption in the vessel wall, particularly in high elastin-content arteries. High apposition pressures substantially increase the equilibrium boiling point of tissue water and are necessary to ensure a high probability of a successful seal. The FDM numerical models illustrate the beneficial effects of high apposition pressures.

  16. Solid-state radar transmitters

    Microsoft Academic Search

    E. D. Ostroff; M. Borkowski; H. Thomas; J. Curtis

    1985-01-01

    The technology and design procedures for introducing transistors into radio transmitters are discussed. The design characteristics of solid-state radar transmitters are described, with emphasis given to power amplifier\\/modules and devices for summing the output power in space or in an output combiner. Some design issues related to power supplies, pulse waveform amplitude regulation; reliability; and cost; and also considered. Some

  17. Photonic radio-frequency dissemination via optical fiber with high-phase stability.

    PubMed

    Wang, Xiaocheng; Liu, Zhangweiyi; Wang, Siwei; Sun, Dongning; Dong, Yi; Hu, Weisheng

    2015-06-01

    We demonstrate a photonic radio-frequency transmission system via optical fiber. Optical radio-frequency signal is generated utilizing a Mach-Zehnder modulator based on double-side-band with carrier suppression modulation scheme. The phase error induced by optical fiber transmission is transferred to an intermediate frequency signal by the dual-heterodyne phase error transfer scheme, and then canceled by a phase locked loop. With precise phase compensation, a radio frequency with high-phase stability can be obtained at the remote end. We performed 20.07-GHz radio-frequency transfer over 100-km optical fiber, and achieved residual phase noise of -65??dBc/Hz at 1-Hz offset frequency, and the RMS timing jitter in the frequency range from 0.01 Hz to 1 MHz reaches 110 fs. The long-term frequency stability also achieves 8×10-17 at 10,000 s averaging time. PMID:26030572

  18. Enhancement of electromagnetic propagation through complex media for Radio Frequency Identification

    E-print Network

    Marti, Uttara P

    2005-01-01

    In this thesis, I present and examine the fundamental limitations involved in Radio Frequency Identification (RFID) as well as provide a means to improve reader-tag communication in ultra high frequency RFID systems. The ...

  19. Application of Modulation Techniques to Atomic Emission Spectrometry with Inductively-Coupled Radio-Frequency Plasma and Radio-Frequency Glow Discharge Plasma

    Microsoft Academic Search

    Kazuaki Wagatsuma

    2002-01-01

    Three novel measuring systems for modulation technique to be applied to atomic emission spectrometry are reviewed. A plasma gas modulation technique is employed for an improvement in the detection sensitivity in inductively-coupled radio-frequency plasma atomic emission spectrometry (ICP-AES). Both an amplitude modulation technique and a bias current modulation technique are effective for obtaining better analytical performance in radio-frequency glow discharge

  20. High-resolution radio study of SNR IC 443 at low radio frequencies

    NASA Astrophysics Data System (ADS)

    Castelletti, G.; Dubner, G.; Clarke, T.; Kassim, N. E.

    2011-10-01

    Aims: We investigate the morphology at low radio frequencies of the supernova remnant (SNR) IC 443 in detail and accurately establish its radio continuum spectral properties. Methods: We used the VLA in multiple configurations to produce high-resolution radio images of IC 443 at 74 and 330 MHz. From these data we produced the first sensitive, spatially resolved spectral analysis of the radio emission at long wavelengths. The changes with position in the radio spectral index were correlated with data in near infrared (NIR) from 2MASS, in gamma-rays from VERITAS, and with the molecular 12CO (J = 1 - 0) line emission. Results: The new image at 74 MHz has HPBW = 35'' and rms = 30 mJy beam-1 and at 330 MHz HPBW = 17'' and rms = 1.7 mJy beam-1. The integrated flux densities for the whole SNR are S74 MHzSNR=470±51 Jy and S330 MHzSNR=248±15 Jy. Improved estimates of the integrated spectrum were derived taking a turnover into account to fit the lowest frequency measurements in the literature. Combining our measurements with existing data, we derive an integrated spectral index ?10 MHz10700 MHz=-0.39±0.01 with a free-free continuum optical depth at 330 MHz ?330 ~ 7 × 10-4 (?10 = 1.07); all measurements above ~ 10 MHz are equally consistent with a power law spectrum. For the pulsar wind nebula associated with the compact source CXOU J061705.3+222127, we calculated S330 MHzPWN=0.23±0.05 Jy, S1420 MHzPWN=0.20±0.04 Jy, and ?330 MHz8460 MHz˜ 0.0. Substantial variations are observed in spectral index between 74 and 330 MHz across IC 443. The flattest spectral components ( - 0.25 ? ? ? - 0.05) coincide with the brightest parts of the SNR along the eastern border, with an impressive agreement with ionic lines as observed in the 2MASS J and H bands. The diffuse interior of IC 443 has a spectrum steeper than found anywhere in the SNR ( - 0.85 ? ? ? - 0.6), while the southern ridge again has a flatter spectrum (? ~ -0.4). With the available statistics the VERITAS ?-ray emission strikingly matches the CO distribution, but no clear evidence is found for a morphological correlation between the TeV distribution and radio emission. Conclusions: The excellent correspondence between the eastern radio flattest spectrum region and NIR ionic lines strongly suggests that the passage of a fast, dissociating J-type shock across the interacting molecular cloud dissociated the molecules and ionized the gas. We therefore conclude that thermal absorption at 74 MHz (?74 up to ~0.3) is responsible for the localized spectral index flattening observed along the eastern border of IC 443. Towards the interior of IC 443, the spectrum is consistent with those expected from linear diffusive shock acceleration, while the flatter spectrum in the southern ridge is a consequence of the strong shock/molecular cloud interaction.

  1. Structural and optical properties of a radio frequency magnetron-sputtered ZnO thin film with different growth angles.

    PubMed

    Ko, Ki-Han; Joung, Yeun-Ho; Choi, Won Seok; Park, Mungi; Lee, Jaehyung; Hwang, Hyun-Suk

    2012-01-01

    This study introduces optical properties of a columnar structured zinc oxide [ZnO] antireflection coating for solar cells. We obtained ZnO films of columnar structure on glass substrates using a specially designed radio frequency magnetron sputtering system with different growth angles. Field-emission scanning electron microscopy was utilized to check the growth angles of the ZnO films which were controlled at 0°, 15°, and 30°. The film thickness was fixed at 100 nm to get a constant experiment condition. Grain sizes of the ZnO films were measured by X-ray diffraction. A UV-visible spectrometer was used to measure the transmittance and reflectance of the ZnO film columnar structures as a function of the growth angles. PMID:22221542

  2. Frequency allocations for passive use of the radio spectrum to make scientific studies

    NASA Technical Reports Server (NTRS)

    Stull, M. A.; Alexander, G.

    1976-01-01

    The paper examines the legal implications of frequency allocations for passive use of the radio spectrum, which refer to receive-only radio services. Such receive-only services refer to the reception of radio signals generated by nonhuman agencies as in radio astronomy or in the search for extraterrestrial intelligence. Juridical interpretations of the public interest and of necessity are applied to these passive services.

  3. Radio-Frequency Tank Eigenmode Sensor for Propellant Quantity Gauging

    NASA Technical Reports Server (NTRS)

    Zimmerli, Gregory A.; Buchanan, David A.; Follo, Jeffrey C.; Vaden, Karl R.; Wagner, James D.; Asipauskas, Marius; Herlacher, Michael D.

    2010-01-01

    Although there are several methods for determining liquid level in a tank, there are no proven methods to quickly gauge the amount of propellant in a tank while it is in low gravity or under low-settling thrust conditions where propellant sloshing is an issue. Having the ability to quickly and accurately gauge propellant tanks in low-gravity is an enabling technology that would allow a spacecraft crew or mission control to always know the amount of propellant onboard, thus increasing the chances for a successful mission. The Radio Frequency Mass Gauge (RFMG) technique measures the electromagnetic eigenmodes, or natural resonant frequencies, of a tank containing a dielectric fluid. The essential hardware components consist of an RF network analyzer that measures the reflected power from an antenna probe mounted internal to the tank. At a resonant frequency, there is a drop in the reflected power, and these inverted peaks in the reflected power spectrum are identified as the tank eigenmode frequencies using a peak-detection software algorithm. This information is passed to a pattern-matching algorithm, which compares the measured eigenmode frequencies with a database of simulated eigenmode frequencies at various fill levels. A best match between the simulated and measured frequency values occurs at some fill level, which is then reported as the gauged fill level. The database of simulated eigenmode frequencies is created by using RF simulation software to calculate the tank eigenmodes at various fill levels. The input to the simulations consists of a fairly high-fidelity tank model with proper dimensions and including internal tank hardware, the dielectric properties of the fluid, and a defined liquid/vapor interface. Because of small discrepancies between the model and actual hardware, the measured empty tank spectra and simulations are used to create a set of correction factors for each mode (typically in the range of 0.999 1.001), which effectively accounts for the small discrepancies. These correction factors are multiplied to the modes at all fill levels. By comparing several measured modes with the simulations, it is possible to accurately gauge the amount of propellant in the tank. An advantage of the RFMG approach of applying computer simulations and a pattern-matching algorithm is that the Although there are several methods for determining liquid level in a tank, there are no proven methods to quickly gauge the amount of propellant in a tank while it is in low gravity or under low-settling thrust conditions where propellant sloshing is an issue. Having the ability to quickly and accurately gauge propellant tanks in low-gravity is an enabling technology that would allow a spacecraft crew or mission control to always know the amount of propellant onboard, thus increasing the chances for a successful mission. The Radio Frequency Mass Gauge (RFMG) technique measures the electromagnetic eigenmodes, or natural resonant frequencies, of a tank containing a dielectric fluid. The essential hardware components consist of an RF network analyzer that measures the reflected power from an antenna probe mounted internal to the tank. At a resonant frequency, there is a drop in the reflected power, and these inverted peaks in the reflected power spectrum are identified as the tank eigenmode frequencies using a peak-detection software algorithm. This information is passed to a pattern-matching algorithm, which compares the measured eigenmode frequencies with a database of simulated eigenmode frequencies at various fill levels. A best match between the simulated and measured frequency values occurs at some fill level, which is then reported as the gauged fill level. The database of simulated eigenmode frequencies is created by using RF simulation software to calculate the tank eigenmodes at various fill levels. The input to the simulations consists of a fairly high-fidelity tank model with proper dimensions and including internal tank harare, the dielectric properties of the fluid, and a defined liquid/vapor interface. Because of sma

  4. NIST Special Publication 250-67 NIST Time and Frequency Radio Stations

    E-print Network

    NIST Special Publication 250-67 NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB Glenn K. Nelson Michael A. Lombardi Dean T. Okayama #12;NIST Special Publication 250-67 NIST Time and Frequency Radio Stations: WWV, WWVH, and WWVB Glenn K. Nelson Michael A. Lombardi Dean T. Okayama Time

  5. A high-performance cryogenic amplifier based on a radio-frequency single electron transistor

    E-print Network

    Segall, Ken

    amplifier based on a radio-frequency single-electron- transistor rf-SET . The high charge sensitivity impedance sources. In this letter we present a demonstration of a high- performance amplifier based on a rfA high-performance cryogenic amplifier based on a radio-frequency single electron transistor K

  6. Exploring radio frequency identification technology and its impact on business systems

    Microsoft Academic Search

    Alan D. Smith

    2005-01-01

    Purpose – To provide practitioners of management a sense of the importance of strategically leveraging the current and historic development of radio frequency identification (RFID) in order to find inexpensive applications of radio frequency-based (RF) technologies in many areas. Design\\/methodology\\/approach – A review of the applied literature on RFID, as well as from practical experience, resulted in a basic model

  7. Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS

    E-print Network

    Gurnett, Donald A.

    Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS N. Meyer 2008; published 7 February 2009. [1] We analyse wave observations by the Cassini/RPWS instrument at radio frequencies: Jovian dust stream impacts on Cassini/RPWS, Geophys. Res. Lett., 36, L03103, doi:10

  8. A Two-Dimensional Model of Chemical Vapor Infiltration With Radio Frequency Heating

    E-print Network

    Economou, Demetre J.

    -consistently the power absorbed by the preform from a radio frequency induction coil. The model equations were solved an "inverted" temperature gradient. As the reactant gas diffuses into the preform, this temperature gradient either in a conven- tional microwave oven or by using a radio frequency (RF) induction coil

  9. A comparative study of radio frequency-based indoor location sensing systems

    Microsoft Academic Search

    Shomit S. Manapure; Houshang Darabi; Vishal Patel; Prashant Banerjee

    2004-01-01

    The growing popularity and use of the radio frequency (RF) in different applications, predominantly in the area of identification and location aware system, has driven many researchers. Versatile qualities, easy availability and simplicity of use have led a spate of development of different systems and technologies based on radio frequency identification (RFID). This paper is an attempt to survey the

  10. Coordinated observations using the world largest low-frequency radio telescopes and space misiions

    NASA Astrophysics Data System (ADS)

    Konovalenko, A. A.; Zarka, Ph.; Kolyadin, V. L.; Zakharenko, V. V.; Stepkin, S. V.; Panchenko, M.; Lecacheux, A.; Rucker, H. O.; Fischer, G.; Ulyanov, O. M.; Melnik, V. N.; Litvinenko, G. V.; Sidorchuk, M. A.; Bubnov, I. N.; Vasilyeva, Ya. Yu.; Bojko, A. I.; Shaposhnikov, V.; Mann, G.; Kalinichenko, N. N.; Falkovich, I. S.; Koval, A. A.; Mylostna, K.; Pylaev, O. S.; Shepelev, V. A.; Reznik, A. P.

    2013-09-01

    The positive possibilities of astrophysical objects studies(including the Solar system investigations) using coordinated observations with the largest existing and coming low frequency radio telescopes are shown. The observations of the Sun, Jupiter, Saturn, ant others with UTR-2, URAN, NDA radio telescopes, and WIND, Cassini and STEREO space missions at frequencies lower than 40 MHz have been carried out.

  11. Controller design issues in the feedback control of radio frequency plasma processing reactors

    E-print Network

    Kushner, Mark

    Controller design issues in the feedback control of radio frequency plasma processing reactors the potential for improving the reliability and performance of radio frequency rf plasma processing reactors for microelectronics etching, deposition, and cleaning applications. Implementation of real-time-control strategies has

  12. An L-band Radio Frequency Interference (RFI) Detection and Mitigation Testbed for Microwave

    E-print Network

    Ruf, Christopher

    An L-band Radio Frequency Interference (RFI) Detection and Mitigation Testbed for Microwave specifically designed to detect and mitigate many types of Radio Frequency Interference (RFI) is described. The L-band RFI Detection and Mitigation Testbed (DetMit Testbed) will not be optimized for radiometric

  13. Nonlinear Exothermic Contributions to RadioFrequency Bonding of Adhesives 1

    E-print Network

    Nonlinear Exothermic Contributions to Radio­Frequency Bonding of Adhesives 1 H.T. Banks 2 S This work describes an effort to model the radio­frequency curing of epoxy adhesives in bonding and adhesively bonded in sandwich fashion around their perimeters to form rigid structures. The adhesive

  14. Low Frequency Radio-wave System for subsurface investigation

    NASA Astrophysics Data System (ADS)

    Soldovieri, Francesco; Gennarelli, Gianluca; Kudelya, Anatoliy; Denisov, Alexander

    2015-04-01

    Low frequency radio-wave methods (RWM) allow subsurface investigations in terms of lithological structure characterization, detection of filtration flows of ground water, anthropogenic and natural cavities. In this contribution, we present a RWM that exploits two coils working at frequencies of few MHz as transmitting and receiving antennas. The basic principle of this inductive method is as follows. The primary alternating electromagnetic field radiated by the transmitting coil induces eddy currents in the subsurface mainly due to the conductivity anomalies. These eddy currents generate a secondary (scattered) magnetic field which overlaps to the incident magnetic field and is detected by the receiving coil. Despite the simple operation of the system, the complexity of the electromagnetic scattering phenomenon at hand must be properly modeled to achieve adequate performance. Therefore, an advanced data processing technique, belonging to the class of the inverse scattering approaches, has been developed by the authors in a full 3D geometry. The proposed method allows to deal with data collected on a scanning surface under a dipole inductive profiling (DIP) modality, where the transmitting/receiving coils are moved simultaneously with fixed offset (multi-bistatic configuration). The hardware, called Dipole Inductive Radio-wave System (DIRS), is composed by an electronic unit and transmitting and receiving loop antennas radiating at frequencies of few MHz (2-4 MHz), which are installed on theodolite supports. The compactness of DIRS and its robustness to external electromagnetic interference offers the possibility to perform geophysical research up to the depth of some tens of meters and under several types of ground and water surfaces, vegetation, and weather conditions. The light weight and small size of system (the single antenna with support weights about 5 kg and has a diameter of 0.5m) allows two operators to perform geophysical research without disturbing the surface integrity of investigated ground massif. The value of base and the value of voltage induced on the digital voltmeter of the receiver are stored in memory on a SD-card for a subsequent visualization and processing. Realistic cases of application of the DIRS system enhanced by the inverse scattering approach will be presented at the conference with regard to the geological characterization of a mine shaft and an archaeological site.

  15. Design, Construction and Operation of a Low-Power, Autonomous Radio-Frequency Data-Acquisition Station for the TARA Experiment

    E-print Network

    Kunwar, S; Allen, C; Belz, J; Besson, D; Byrne, M; Farhang-Boroujeny, B; Gillman, W H; Hanlon, W; Hanson, J; Myers, I; Novikov, A; Prohira, S; Ratzlaff, K; Rezazadeh, A; Sanivarapu, V; Schurig, D; Shustov, A; Smirnova, M; Takai, H; Thomson, G B; Young, R

    2015-01-01

    Employing a 40-kW radio-frequency transmitter just west of Delta, UT, and operating at 54.1 MHz, the TARA (Telescope Array RAdar) experiment seeks radar detection of extensive air showers (EAS) initiated by ultra-high energy cosmic rays (UHECR). For UHECR with energies in excess of $10^{19}$ eV, the Doppler-shifted "chirps" resulting from EAS shower core radar reflections should be observable above background (dominantly galactic) at distances of tens of km from the TARA transmitter. In order to stereoscopically reconstruct cosmic ray chirps, two remote, autonomous self-powered receiver stations have been deployed. Each remote station (RS) combines both low power consumption as well as low cost. Triggering logic, the powering and communication systems, and some specific details of hardware components are discussed.

  16. Signal processing approaches to radio frequency interference (RFI) suppression

    NASA Astrophysics Data System (ADS)

    Braunstein, Matthew; Ralston, James M.; Sparrow, David A.

    1994-06-01

    Ultra-wideband radar (UWB) has been shown to be among the most powerful techniques available for underground and obscured object detection. The value of such systems is that they combine the penetration enhancement associated with VHF/UHF (and lower) frequencies with the resolution of wide absolute bandwidth. Such systems necessarily make use of much of the frequency spectrum already in heavy use by other services, such as television and mobile communications. Although this spectral overlap provides occasion for adverse consequences in both directions, to date the principal consequence has been often-severe impact on UWB radar measurements. Even in remote locations, the average interference power often exceeds receiver noise by many dB, becoming the limiting factor on system sensitivity. Nor are UWB radar designers free to overcome this interference by increasing radar power, since regulatory sanction for UWB operation will depend on maintaining sufficiently low spectral power densities to assure that other, prior, services are not appreciably degraded. Given the importance of radio frequency interference (RFI) on practical ultrawide band ground penetrating radar systems, it is important to consider how and to what extent the effects of RFI noise may be reduced. The overall problem of RFI and its impacts will be described and several signal processing approaches to removal of RFI will be discussed. These include spectral estimation and coherent subtraction algorithms and various filter approaches, which have been developed and applied by the signal processing community in other contexts. These methods will be applied to several different real-world experimental data sets, and quantitative measures of the effectiveness of each of these algorithms in removing RFI noise will be presented. Although computationally-intensive, most of the techniques to be described achieve substantial increases in S/RFI without requiring concomitant increases in radar average power.

  17. Low-power UWB transmitter using a combined mixer and power amplifier

    Microsoft Academic Search

    Silvia Soldà; M. Caruso; Daniele Vogrig; Andrea Bevilacqua; Andrea Gerosa; Andrea Neviani

    2010-01-01

    This paper presents an energy-efficient transmitter for UWB impulse-radio. The proposed circuit uses a novel combined mixer and power amplifier to generate a Gaussian pulse with 1.25GHz bandwidth and center frequency of 7.87GHz. The combined MXR-PA includes a monolithic transformer to reach a maximum output voltage swing of 3.2Vpp. The transformer has been designed so as to maximize the transmitter

  18. December 6, 1985 EstiBate of the Radio Frequency Properties of the Vacuue Chamber

    E-print Network

    Kemner, Ken

    LS- 43 December 6, 1985 T. Khoe EstiBate of the Radio Frequency Properties of the Vacuue Chamber 1. Cutoff frequencies The lowest cutoff frequency is that of the TE waves. A very approximate calculation of the cutoff frequency can be made by considering region II as a capacitance and regions I and III

  19. Dynamics of ion-ion plasmas under radio frequency bias Vikas Midhaa)

    E-print Network

    Economou, Demetre J.

    Dynamics of ion-ion plasmas under radio frequency bias Vikas Midhaa) and Demetre J. Economoub equation for the electrostatic field. Special emphasis was placed on the effect of applied bias frequency profound structure changes as the bias frequency is varied. For low bias frequencies 100 kHz , the charge

  20. OLFAR: the orbiting low frequency array, how a cube sat swarm becomes a novel radio astronomy instrument in space

    Microsoft Academic Search

    Mark Bentum; Arjan Meijerink; Albert-Jan Boonstra; Chris Verhoeven; Veen van der Alle-Jan

    2010-01-01

    To study the physical processes in the Universe, observations are done at various wavelengths, from Gamma rays to optical and radio frequencies. At this moment research at low frequencies is one of the major topics in radio astronomy. Several Earth-based radio telescopes are being built and will be operational very soon (for instance the LOFAR radio telescope in the Netherlands

  1. Adhoc electromagnetic compatibility testing of non-implantable medical devices and radio frequency identification

    PubMed Central

    2013-01-01

    Background The use of radiofrequency identification (RFID) in healthcare is increasing and concerns for electromagnetic compatibility (EMC) pose one of the biggest obstacles for widespread adoption. Numerous studies have documented that RFID can interfere with medical devices. The majority of past studies have concentrated on implantable medical devices such as implantable pacemakers and implantable cardioverter defibrillators (ICDs). This study examined EMC between RFID systems and non-implantable medical devices. Methods Medical devices were exposed to 19 different RFID readers and one RFID active tag. The RFID systems used covered 5 different frequency bands: 125–134 kHz (low frequency (LF)); 13.56 MHz (high frequency (HF)); 433 MHz; 915 MHz (ultra high frequency (UHF])) and 2.4 GHz. We tested three syringe pumps, three infusion pumps, four automatic external defibrillators (AEDs), and one ventilator. The testing procedure is modified from American National Standards Institute (ANSI) C63.18, Recommended Practice for an On-Site, Ad Hoc Test Method for Estimating Radiated Electromagnetic Immunity of Medical Devices to Specific Radio-Frequency Transmitters. Results For syringe pumps, we observed electromagnetic interference (EMI) during 13 of 60 experiments (22%) at a maximum distance of 59 cm. For infusion pumps, we observed EMI during 10 of 60 experiments (17%) at a maximum distance of 136 cm. For AEDs, we observed EMI during 18 of 75 experiments (24%) at a maximum distance of 51 cm. The majority of the EMI observed was classified as probably clinically significant or left the device inoperable. No EMI was observed for all medical devices tested during exposure to 433 MHz (two readers, one active tag) or 2.4 GHz RFID (two readers). Conclusion Testing confirms that RFID has the ability to interfere with critical medical equipment. Hospital staff should be aware of the potential for medical device EMI caused by RFID systems and should be encouraged to perform on-site RF immunity tests prior to RFID system deployment or prior to placing new medical devices in an RFID environment. The methods presented in this paper are time-consuming and burdensome and suggest the need for standard test methods for assessing the immunity of medical devices to RFID systems. PMID:23845013

  2. Low-temperature growth of InxGa1-xN films by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, J.; Shi, X. J.; Zhu, J.

    2013-01-01

    The low-temperature growth of InxGa1-xN films on quartz glass substrates utilizing radio-frequency magnetron sputtering is investigated. In the InxGa1-xN films prepared using an In-Ga alloy target, grazing incidence X-ray diffraction (GIXRD) peaks corresponding to wurtzite structure were observed. X-ray photoelectron spectroscopy (XPS) was applied to study the extent of oxygen contamination and chemical states, and secondary ion mass spectrometry (SIMS) was used to evaluate the distribution profiles of oxygen impurity in the as-grown InxGa1-xN thin films. XPS and SIMS analysis indicate that the entire thin films have oxide phases. However, no evidence of In2O3, Ga2O3, or indium oxynitride phases was shown in XRD studies. It may be predicted that the oxygen impurities formed amorphous oxide phases embedded in InxGa1-xN matrix. According to our findings, indium is a major phase in the InxGa1-xN thin films which suggests that a significant amount of indium remains un-reacted with N2. The optical transmittance spectra of the as-grown films show interference fringe patterns. The indium fraction x of the as-deposited InxGa1-xN thin films can be calculated out by the transmittance data.

  3. THE LOW-FREQUENCY RADIO CATALOG OF FLAT-SPECTRUM SOURCES

    SciTech Connect

    Massaro, F. [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); D'Abrusco, R.; Paggi, A.; Cowperthwaite, Philip S. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Masetti, N. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy); Funk, S., E-mail: fmassaro79@gmail.com [Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States)

    2014-07-01

    A well known property of the ?-ray sources detected by Cos-B in the 1970s, by the Compton Gamma-Ray Observatory in the 1990s, and recently by the Fermi observations is the presence of radio counterparts, particularly for those associated with extragalactic objects. This observational evidence is the basis of the radio-?-ray connection established for the class of active galactic nuclei known as blazars. In particular, the main spectral property of the radio counterparts associated with ?-ray blazars is that they show a flat spectrum in the GHz frequency range. Our recent analysis dedicated to search blazar-like candidates as potential counterparts for the unidentified ?-ray sources allowed us to extend the radio-?-ray connection in the MHz regime. We also showed that blazars below 1 GHz maintain flat radio spectra. Thus, on the basis of these new results, we assembled a low-frequency radio catalog of flat-spectrum sources built by combining the radio observations of the Westerbork Northern Sky Survey and of the Westerbork in the southern hemisphere catalog with those of the NRAO Very Large Array Sky survey (NVSS). This could be used in the future to search for new, unknown blazar-like counterparts of ?-ray sources. First, we found NVSS counterparts of Westerbork Synthesis Radio Telescope radio sources, and then we selected flat-spectrum radio sources according to a new spectral criterion, specifically defined for radio observations performed below 1 GHz. We also described the main properties of the catalog listing 28,358 radio sources and their logN-logS distributions. Finally, a comparison with the Green Bank 6 cm radio source catalog was performed to investigate the spectral shape of the low-frequency flat-spectrum radio sources at higher frequencies.

  4. Modulation of Radio Frequency Signals by Nonlinearly Generated Acoustic Fields

    NASA Astrophysics Data System (ADS)

    Johnson, Spencer Joseph

    Acousto-electromagnetic scattering is a process in which an acoustic excitation is utilized to induce modulation on an electromagnetic (EM) wave. This phenomenon can be exploited in remote sensing and detection schemes whereby target objects are mechanically excited by high powered acoustic waves resulting in unique object characterizations when interrogated with EM signals. Implementation of acousto-EM sensing schemes, however, are limited by a lack of fundamental understanding of the nonlinear interaction between acoustic and EM waves and inefficient simulation methods in the determination of the radiation patterns of higher order scattered acoustic fields. To address the insufficient simulation issue, a computationally efficient mathematical model describing higher order scattered sound fields, particularly of third-order in which a 40x increase in computation speed is achieved, is derived using a multi-Gaussian beam (MGB) expansion that expresses the sound field of any arbitrary axially symmetric beam as a series of Gaussian base functions. The third-order intermodulation (IM3) frequency components are produced by considering the cascaded nonlinear second-order effects when analyzing the interaction between the first- and second-order frequency components during the nonlinear scattering of sound by sound from two noncollinear ultrasonic baffled piston sources. The theory is extended to the modeling of the sound beams generated by parametric transducer arrays, showing that the MGB model can be efficiently used to calculate both the second- and third-order sound fields of the array. Additionally, a near-to-far-field (NTFF) transformation method is developed to model the far-field characteristics of scattered sound fields, extending Kirchhoff's theorem, typically applied to EM waves, determining the far-field patterns of an acoustic source from amplitude and phase measurements made in the near-field by including the higher order sound fields generated by the nonlinear scattering of sound by sound as the acoustic waves propagate into the far-field. With improvements in the sensitivity of radio frequency (RF) receivers, spectral content previously below the measurable noise floor, such as the nonlinear content produced by acousto-EM scattering, can now be examined and analyzed. Through the use of a high dynamic range nonlinear measurement system based on analog cancellation, the ability to experimentally investigate the effects of nonlinear interaction between acoustic and EM waves previously unattainable is enabled. To further the understanding of the effects of acousto-EM scattering and verify experimental results, a mathematical description of the periodic change in the medium characteristics due to the propagation of a high powered acoustic wave through a medium that modulates an EM signal proportional to the acoustic frequency is developed.

  5. A new design for a very low frequency spaceborne radio interferometer

    Microsoft Academic Search

    Divya Oberoi; Jean-Louis Pinçon

    2005-01-01

    The nontransparency and severe propagation effects of the terrestrial ionosphere make it impossible for Earth-based instruments to study the universe at low radio frequencies. An exploration of the low-frequency radio window with the resolution and sensitivity essential to meet the scientific objectives will necessarily require a dedicated satellite-based interferometer operating at these frequencies. Such missions have been proposed in the

  6. Radio frequency coil technology for small-animal MRI.

    PubMed

    Doty, F David; Entzminger, George; Kulkarni, Jatin; Pamarthy, Kranti; Staab, John P

    2007-05-01

    A review of the theory, technology, and use of radio frequency (RF) coils for small-animal MRI is presented. It includes a brief overview of MR signal-to-noise (S/N) analysis and discussions of the various coils commonly used in small-animal MR: surface coils, linear volume coils, birdcages, and their derivatives. The scope is limited to mid-range coils, i.e. coils where the product (fd) of the frequency f and the coil diameter d is in the range 2-30 MHz-m. Common applications include mouse brain and body coils from 125 to 750 MHz, rat body coils up to 500 MHz, and small surface coils at all fields. In this regime, all the sources of loss (coil, capacitor, sample, shield, and transmission lines) are important. All such losses may be accurately captured in some modern full-wave 3D electromagnetics software, and new simulation results are presented for a selection of surface coils using Microwave Studio 2006 by Computer Simulation Technology, showing the dramatic importance of the "lift-off effect". Standard linear circuit simulators have been shown to be useful in optimization of complex coil tuning and matching circuits. There appears to be considerable potential for trading S/N for speed using phased arrays, especially for a larger field of view. Circuit simulators are shown to be useful for optimal mismatching of ultra-low-noise preamps based on the enhancement-mode pseudomorphic high-electron-mobility transistor for optimal coil decoupling in phased arrays. Cryogenically cooled RF coils are shown to offer considerable opportunity for future gains in S/N in smaller samples. PMID:17451180

  7. Monitoring of tumor radio frequency ablation using derivative spectroscopy

    NASA Astrophysics Data System (ADS)

    Spliethoff, Jarich W.; Tanis, Erik; Evers, Daniel J.; Hendriks, Benno H. W.; Prevoo, Warner; Ruers, Theo J. M.

    2014-09-01

    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffuse reflectance (DR) spectra were measured from human blood samples during gradual heating of the samples from 37 to 60, 70, and 85°C. Additionally, reflectance spectra were recorded real-time during RF ablation of human liver tissue ex vivo and in vivo. Specific spectral characteristics of methemoglobin were extracted from the spectral slopes using a custom optical ablation ratio. Thermal coagulation of blood caused significant changes in the spectral slopes, which is thought to be caused by the formation of methemoglobin. The time course of these changes was clearly dependent on the heating temperature. RF ablation of liver tissue essentially led to similar spectral alterations. In vivo DR measurements confirmed that the method could be used to assess the degree of thermal damage during RF ablation and long after the tissue cooled.

  8. Cruising through molecular bound state manifolds with radio frequency

    E-print Network

    F. Lang; P. v. d. Straten; B. Brandstätter; G. Thalhammer; K. Winkler; P. S. Julienne; R. Grimm; J. Hecker Denschlag

    2007-08-29

    The emerging field of ultracold molecules with their rich internal structure is currently attracting a lot of interest. Various methods have been developed to produce ultracold molecules in pre-set quantum states. For future experiments it will be important to efficiently transfer these molecules from their initial quantum state to other quantum states of interest. Optical Raman schemes are excellent tools for transfer, but can be involved in terms of equipment, laser stabilization and finding the right transitions. Here we demonstrate a very general and simple way for transfer of molecules from one quantum state to a neighboring quantum state with better than 99% efficiency. The scheme is based on Zeeman tuning the molecular state to avoided level crossings where radio-frequency transitions can then be carried out. By repeating this process at different crossings, molecules can be successively transported through a large manifold of quantum states. As an important spin-off of our experiments, we demonstrate a high-precision spectroscopy method for investigating level crossings.

  9. The Stabiliy of Radio-Frequency Plasma Treated Polydimethylsiloxane Surface

    PubMed Central

    Chen, I-Jane

    2008-01-01

    Polydimethylsiloxane (PDMS) is a widely used material for manufacturing lab-on-chip devices. However, the hydrophobic nature of PDMS is a disadvantage in micro-fluidic systems. To transform the hydrophobic PDMS surface to hydrophilic it has been treated with radio frequency (RF) air plasma at 150, 300 and 500 mtorr pressure for up to 30 minutes. Following the surface treatment, the PDMS specimens were stored in air, deionized water or 0.14 M NaCl solution at 4 °C, 20 °C, and 70 °C. The change in the hydrophilicity (wettability) of the PDMS surfaces has been followed by contact angle measurements and Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) Spectroscopy as a function of time. As an effect of the RF plasma treatment the contact angles measured on PDMS surfaces dropped from 113±4 degrees to 9±3 degrees. The chamber pressure and the treatment time had no or negligible effect on the results. However, the PDMS surface gradually lost its hydrophilic properties in time. The rate of this process is influenced by the difference in the dielectric constants of the PDMS and its ambient environment. It has been the smallest at low temperatures in deionized water and largest at high temperatures in air. Apparently, the OH groups generated on the PDMS surface during the plasma treatment tend towards a more hydrophilic/less hydrophobic environment during the relaxation processes. The correlation between FTIR–ATR spectral information and contact angle data supports this interpretation. PMID:17279784

  10. An Analytical Model for the Radio-Frequency Sheath

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe

    2013-09-01

    An analytical model for the planar radio frequency (RF) sheath in capacitive discharges is developed based on the applied RF voltage as the boundary condition. In a first step, the individual sheath voltages and the self-bias are calculated using a cubic-charge voltage relation. In the second step, a single integro-differential equation is derived to describe the ion flow velocity in the sheath under all conditions of collisionality. Central to the model is the screening function that describes the screening of the ion density by the mean electron density in the sheath. Numerical integration of the sheath equation is straight forward. However, for the collisionless as well as the collisional case explicit, simple, and precise analytical approximations can be found. Drift velocities, densities, fields, currents, and charge-voltage relations are calculated. Further, the Child-Langmuir laws for both cases of collisonality are derived. These solutions are in very good agreement with experimental data from the literature based on laser electric field measurements, the Brinkmann sheath model, and PIC simulations. The technique works well also for other waveforms, e.g. the electrical asymmetry effect or tailored pulse waveforms.

  11. Noninvasive radio frequency for skin tightening and body contouring.

    PubMed

    Weiss, Robert A

    2013-03-01

    The medical use of radio frequency (RF) is based on an oscillating electrical current forcing collisions between charged molecules and ions, which are then transformed into heat. RF heating occurs irrespective of chromophore or skin type and is not dependent on selective photothermolysis. RF can be delivered using monopolar, bipolar, and unipolar devices, and each method has theoretical limits of depth penetration. A variant of bipolar delivery is fractional RF delivery. In monopolar configurations, RF will penetrate deeply and return via a grounding electrode. Multiple devices are available and are detailed later in the text. RF thermal stimulation is believed to result in a microinflammatory process that promotes new collagen. By manipulating skin cooling, RF can also be used for heating and reduction of fat. Currently, the most common uses of RF-based devices are to noninvasively manage and treat skin tightening of lax skin (including sagging jowls, abdomen, thighs, and arms), as well as wrinkle reduction, cellulite improvement, and body contouring. PMID:24049924

  12. A graphical approach to radio frequency quadrupole design

    NASA Astrophysics Data System (ADS)

    Turemen, G.; Unel, G.; Yasatekin, B.

    2015-07-01

    The design of a radio frequency quadrupole, an important section of all ion accelerators, and the calculation of its beam dynamics properties can be achieved using the existing computational tools. These programs, originally designed in 1980s, show effects of aging in their user interfaces and in their output. The authors believe there is room for improvement in both design techniques using a graphical approach and in the amount of analytical calculations before going into CPU burning finite element analysis techniques. Additionally an emphasis on the graphical method of controlling the evolution of the relevant parameters using the drag-to-change paradigm is bound to be beneficial to the designer. A computer code, named DEMIRCI, has been written in C++ to demonstrate these ideas. This tool has been used in the design of Turkish Atomic Energy Authority (TAEK)'s 1.5 MeV proton beamline at Saraykoy Nuclear Research and Training Center (SANAEM). DEMIRCI starts with a simple analytical model, calculates the RFQ behavior and produces 3D design files that can be fed to a milling machine. The paper discusses the experience gained during design process of SANAEM Project Prometheus (SPP) RFQ and underlines some of DEMIRCI's capabilities.

  13. Large-area radio frequency plasma sources for fusion applications

    NASA Astrophysics Data System (ADS)

    Kraus, W.; Speth, E.; Feist, J.-H.; Frank, P.; Heinemann, B.; Riedl, R.; Trainham, R.; Jacquot, C.

    1998-02-01

    Four powerful inductively coupled radio frequency (rf) plasma generators producing 90 A, 55 kV hydrogen beams were manufactured for the second injector of ASDEX Upgrade. The design of the source and the power supply was optimized based on the experience with a prototype source. During conditioning of the first two sources, it was demonstrated that power efficiency, transmission of the beam power and reliability meet all requirements. The start of the neutral beam injection with the second injector is scheduled for October 1997. Recently, also negative ions in rf sources are being investigated within a collaboration with CEA Cadarache. In this development project a positive ion prototype rf source is being utilized with a small extraction area (48 cm2) and a 700 G cm magnetic filter. Without cesium a current density of 4.5 mA/cm2 was achieved so far at elevated pressure (1.6 Pa), the H--current density being proportional to the rf power. At medium pressure (0.6 Pa) the current density is lower approximately by a factor of 5, but preliminary results with cesium injection show a relative increase by almost the same factor in this pressure range. Probe measurements indicate electron temperatures of 2.5-4.5 eV close to the plasma grid. Attempts to improve the performance by better plasma confinement, different wall materials, and filter strengths are under way.

  14. Analyzing Radio-Frequency Coverage for the ISS

    NASA Technical Reports Server (NTRS)

    Bolen, Steven M.; Sham, Catherine C.

    2007-01-01

    The Interactive Coverage Analysis Tool (iCAT) is an interactive desktop computer program serving to (1) support planning of coverage, and management of usage of frequencies, of current and proposed radio communication systems on and near the International Space Station (ISS) and (2) enable definition of requirements for development of future such systems. The iCAT can also be used in design trade studies for other (both outer-space and terrestrial) communication systems. A user can enter the parameters of a communication-system link budget in a table in a worksheet. The nominal (onaxis) link values for the bit-to-noise-energy ratio, received isotropic power (RIP), carrier-to-noise ratio (C/N), power flux density (PFD), and link margin of the system are calculated and displayed in the table. Plots of field gradients for the RIP, C/N, PFD, and link margin are constructed in an ISS coordinate system, at a specified link range, for both the forward and return link parameters, and are displayed in worksheets. The forward and reverse link antenna gain patterns are also constructed and displayed. Line-of-sight (LOS) obstructions can be both incorporated into the gradient plots and displayed on separate plots.

  15. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    SciTech Connect

    Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

    2009-11-11

    Ceralink Inc. developed FastFuse™, a rapid, new, energy saving process for lamination of glass and composites using radio frequency (RF) heating technology. The Inventions and Innovations program supported the technical and commercial research and development needed to elevate the innovation from bench scale to a self-supporting technology with significant potential for growth. The attached report provides an overview of the technical and commerical progress achieved for FastFuse™ during the course of the project. FastFuse™ has the potential to revolutionize the laminate manufacturing industries by replacing energy intensive, multi-step processes with an energy efficient, single-step process that allows higher throughput. FastFuse™ transmits RF energy directly into the interlayer to generate heat, eliminating the need to directly heat glass layers and the surrounding enclosures, such as autoclaves or vacuum systems. FastFuse™ offers lower start-up and energy costs (up to 90% or more reduction in energy costs), and faster cycles times (less than 5 minutes). FastFuse™ is compatible with EVA, TPU, and PVB interlayers, and has been demonstrated for glass, plastics, and multi-material structures such as photovoltaics and transparent armor.

  16. Rapid prototyping for radio-frequency geolocation applications

    SciTech Connect

    Briles, S. C. (Scott C.); Arrowood, J. L. (Joseph L.); Braun, T. R. (Thomas R.); Turcotte, D. (Dakx); Fiset, E. (Etienne)

    2004-01-01

    Previous space-to-ground, single-platform geolocation experiments exploiting time-difference-of arrival (TDOA) via interferometry were successful at separating and quantitatively characterizing interfering radio frequency (RF) signals from expected RF transmissions. Much of the success of these experiments rested on the use of embedded processors to perform the required signal processing. The experiments handled data in a 'snapshot' fashion: digitized data was collected, the data was processed via a digital signal processing (DSP) microprocessor to yield differential phase measurements, and these measurements were transmitted to the Earth for geolocation processing. With the utilization of FPGAs (field programmable gate arrays) for the intensive number-crunching algorithms, the processing of streaming real-time data is feasible for bandwidths on the order of 20 MHz. By partitioning the signal processing algorithm so there is a significant reduction in the data rate as data flows through the FPGA, a DSP microprocessor can now be employed to perform further decision-oriented processing on the FPGA output. This hybrid architecture, employing both FPGAs and DSPs, typically requires an expensive and lengthy development cycle. However, the use of graphical development environments with auto-code generation and hardware-in-the-loop testing can result in rapid prototyping for geolocation experiments, which enables adaptation to emerging signals of interest in a cost and time effective manner.

  17. Radio-frequency energy quantification in magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Alon, Leeor

    Mapping of radio frequency (RF) energy deposition has been challenging for 50+ years, especially, when scanning patients in the magnetic resonance imaging (MRI) environment. As result, electromagnetic simulation software is often used for estimating the specific absorption rate (SAR), the rate of RF energy deposition in tissue. The thesis work presents challenges associated with aligning information provided by electromagnetic simulation and MRI experiments. As result of the limitations of simulations, experimental methods for the quantification of SAR were established. A system for quantification of the total RF energy deposition was developed for parallel transmit MRI (a system that uses multiple antennas to excite and image the body). The system is capable of monitoring and predicting channel-by-channel RF energy deposition, whole body SAR and capable of tracking potential hardware failures that occur in the transmit chain and may cause the deposition of excessive energy into patients. Similarly, we demonstrated that local RF power deposition can be mapped and predicted for parallel transmit systems based on a series of MRI temperature mapping acquisitions. Resulting from the work, we developed tools for optimal reconstruction temperature maps from MRI acquisitions. The tools developed for temperature mapping paved the way for utilizing MRI as a diagnostic tool for evaluation of RF/microwave emitting device safety. Quantification of the RF energy was demonstrated for both MRI compatible and non-MRI-compatible devices (such as cell phones), while having the advantage of being noninvasive, of providing millimeter resolution and high accuracy.

  18. Dynamic impedance measurements during radio-frequency heating of cornea.

    PubMed

    Choi, Bernard; Kim, Jihoon; Welch, Ashley J; Pearce, John A

    2002-12-01

    Hyperopia affects approximately 25% of the population. The aim of different heating modalities for the treatment of hyperopia is to steepen the central curvature of the cornea. Conductive keratoplasty (CK) involves the placement of radio-frequency (RF) lesions around a 7-mm-diameter ring concentric with the pupil of the eye. Dynamics of lesion formation during CK depend on corneal electrical impedance, which is expected to change during each 600-ms-long macropulse. The purpose of this study was to measure impedance dynamics during CK. RF lesions were made in in vitro porcine eyes at different power settings. Voltage and current measurements were acquired using a high-speed computer-based data acquisition system. Root-mean-square voltages (VRMS) and curre (IRMS) were calculated for each micropulse, and impedance was determined by calculating the quotient VRMS/IRMS. Initial corneal impedance in vitro was approximately 2000 ohms. During the macropulse, impedance decreased initially due to increased mobility of conductive ions. At higher power settings (e.g., > 70%, or maximum peak-to-peak voltage of 233 V), impedance increased after the initial decrease, indicative of local water vaporization and/or tissue coagulation. Preliminary impedance data obtained for in vivo porcine eyes were similar in magnitude to the in vitro values. PMID:12549743

  19. Method of making radio frequency ion source antenna

    DOEpatents

    Ehlers, Kenneth W. (Alamo, CA); Leung, Ka-Ngo (Hercules, CA)

    1988-01-01

    In the method, the radio frequency (RF) antenna is made by providing a clean coil made of copper tubing or other metal conductor, which is coated with a tacky organic binder, and then with a powdered glass frit, as by sprinkling the frit uniformly over the binder. The coil is then heated internally in an inert gas atmosphere, preferably by passing an electrical heating current along the coil. Initially, the coil is internally heated to about 200.degree. C. to boil off the water from the binder, and then to about 750.degree. C.-850.degree. C. to melt the glass frit, while also burning off the organic binder. The melted frit forms a molten glass coating on the metal coil, which is then cooled to solidify the glass, so that the metal coil is covered with a thin continuous homogeneous impervious glass coating of substantially uniform thickness. The glass coating affords complete electrical insulation and complete dielectric protection for the metal coil of the RF antenna, to withstand voltage breakdown and to prevent sputtering, while also doubling the plasma generating efficiency of the RF antenna, when energized with RF power in the vacuum chamber of an ion source for a particle accelerator or the like. The glass frit preferably contains apprxoimately 45% lead oxide.

  20. Radio-frequency capacitance spectroscopy of metallic nanoparticles.

    PubMed

    Frake, James C; Kano, Shinya; Ciccarelli, Chiara; Griffiths, Jonathan; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka; Smith, Charles G; Buitelaar, Mark R

    2015-01-01

    Recent years have seen great progress in our understanding of the electronic properties of nanomaterials in which at least one dimension measures less than 100?nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge as even state-of-the-art nanofabrication techniques such as electron-beam lithography have a resolution of a few nm at best. Here we present a fabrication and measurement technique that allows high sensitivity and high bandwidth readout of discrete quantum states of metallic nanoparticles which does not require nm resolution or precision. This is achieved by coupling the nanoparticles to resonant electrical circuits and measurement of the phase of a reflected radio-frequency signal. This requires only a single tunnel contact to the nanoparticles thus simplifying device fabrication and improving yield and reliability. The technique is demonstrated by measurements on 2.7?nm thiol coated gold nanoparticles which are shown to be in excellent quantitative agreement with theory. PMID:26042729

  1. Monitoring of tumor radio frequency ablation using derivative spectroscopy.

    PubMed

    Spliethoff, Jarich W; Tanis, Erik; Evers, Daniel J; Hendriks, Benno H W; Prevoo, Warner; Ruers, Theo J M

    2014-09-01

    Despite the widespread use of radio frequency (RF) ablation, an effective way to assess thermal tissue damage during and after the procedure is still lacking. We present a method for monitoring RF ablation efficacy based on thermally induced methemoglobin as a marker for full tissue ablation. Diffuse reflectance (DR) spectra were measured from human blood samples during gradual heating of the samples from 37 to 60, 70, and 85°C. Additionally, reflectance spectra were recorded real-time during RF ablation of human liver tissue ex vivo and in vivo. Specific spectral characteristics of methemoglobin were extracted from the spectral slopes using a custom optical ablation ratio. Thermal coagulation of blood caused significant changes in the spectral slopes, which is thought to be caused by the formation of methemoglobin. The time course of these changes was clearly dependent on the heating temperature. RF ablation of liver tissue essentially led to similar spectral alterations. In vivo DR measurements confirmed that the method could be used to assess the degree of thermal damage during RF ablation and long after the tissue cooled. PMID:25239499

  2. Operating a radio-frequency plasma source on water vapor.

    PubMed

    Nguyen, Sonca V T; Foster, John E; Gallimore, Alec D

    2009-08-01

    A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n(i) approximately = n(e), where n(i) is the positive ion density. But in the electronegative water plasma, quasineutrality requires n(i+) = n(i-) + n(e). The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production. PMID:19725651

  3. A Graphical Approach to Radio Frequency Quadrupole Design

    E-print Network

    Turemen, G; Yasatekin, B

    2014-01-01

    The design of a radio frequency quadrupole, an important section of all ion accelerators, and the calculation of its beam dynamics properties can be achieved using the existing computational tools. These programs, originally designed in 1980s, show effects of aging in their user interfaces and in their output. The authors believe there is room for improvement in both design techniques using a graphical approach and in the amount of analytical calculations before going into CPU burning finite element analysis techniques. Additionally an emphasis on the graphical method of controlling the evolution of the relevant parameters using the drag-to-change paradigm is bound to be beneficial to the designer. A computer code, named DEMIRCI, has been written in C++ to demonstrate these ideas. This tool has been used in the design of Turkish Atomic Energy Authority (TAEK)'s 1.5 MeV proton beamline at Saraykoy Nuclear Research and Training Center (SANAEM). DEMIRCI starts with a simple analytical model, calculates the RFQ b...

  4. A whole body statistical shape model for radio frequency simulation.

    PubMed

    Lee, Su-Lin; Ali, Khaleda; Brizzi, Alessio; Keegan, Jennifer; Hao, Yang; Yang, Guang-Zhong

    2011-01-01

    The development of ultra low power wireless sensors for customized wearable and implantable medical devices requires patient specific models for radio frequency simulation to understand wave propagation in the body. In practice, the creation of a patient specific whole-body model is difficult and time consuming to create. It is therefore necessary to establish a method for studying a population in a statistical manner. In this paper, we present a statistical shape model for the whole body for RF simulation. It is built from 10 male and 10 female subjects of varying size and height. This model has the ability to instantiate a new surface mesh with the parameters allowed by the training set. This model would provide shapes of varying sizes for studies, without the requirement of obtaining subject specific whole body models. Results from finite-differences time-domain simulation are presented on the extreme shapes from the model and demonstrate the need for a full understanding of the range in body shapes. PMID:22255985

  5. Single-electron transistor as a radio-frequency mixer R. Knobel, C. S. Yung, and A. N. Clelanda)

    E-print Network

    Knobel, Robert

    Single-electron transistor as a radio-frequency mixer R. Knobel, C. S. Yung, and A. N. Clelanda-electron transistor as a radio-frequency mixer, based on the nonlinear dependence of current on gate charge of the SET is matched to a 50 cable. This technique, termed a radio-frequency SET rf-SET , allows operation

  6. Fast modeling of the low-pressure capacitively coupled radio-frequency discharge based on the nonlocal approach

    E-print Network

    Kaganovich, Igor

    Fast modeling of the low-pressure capacitively coupled radio-frequency discharge based August 1996 The results of modeling a low-pressure capacitively coupled radio-frequency rf discharge of electron and ion processes in low-pressure radio-frequency rf glow dis- charges has stimulated experimental

  7. Plasma sheath model and ion energy distribution for all radio frequencies Theodoros Panagopoulos and Demetre J. Economoua)

    E-print Network

    Economou, Demetre J.

    Plasma sheath model and ion energy distribution for all radio frequencies Theodoros Panagopoulos electropositive glow discharge were studied with a model that is valid for arbitrary radio frequencies rf formed over a radio frequency rf powered electrode immersed in a plasma is important from both

  8. 3742 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 47, NO. 11, NOVEMBER 2009 Microwave Radiometer Radio-Frequency

    E-print Network

    Ruf, Christopher

    Radiometer Radio-Frequency Interference Detection Algorithms: A Comparative Study Sidharth Misra, Priscilla N, and Joel T. Johnson, Fellow, IEEE Abstract--Two algorithms used in microwave radiometry for radio-frequency of radio-frequency interference (RFI) have begun to be observed by a number of spaceborne microwave

  9. 1448 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 50, NO. 5, MAY 2012 Analysis of Radio Frequency Interference Detection

    E-print Network

    Ruf, Christopher

    , and Christopher S. Ruf, Fellow, IEEE Abstract--Radio frequency interference (RFI) detection tech- niques have) are considered. Index Terms--Interferometry, microwave radiometry, radio frequency interference (RFI), Soil radio frequency interference (RFI) signals corrupting Tb measurements at the L-band. Initial SMOS

  10. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 46, NO. 10, OCTOBER 2008 3123 Detection of Radio-Frequency Interference

    E-print Network

    Ruf, Christopher

    of Radio-Frequency Interference for the Aquarius Radiometer Sidharth Misra and Christopher S. Ruf, Fellow, IEEE Abstract--A radio-frequency interference (RFI) detection algo- rithm has been developed to measure SSS [2]. The contamination of radiometer data is possible if man-made sources of radio- frequency

  11. Low-power radio-frequency ICs for portable communications

    Microsoft Academic Search

    ASAD A. ABIDI

    1995-01-01

    The contributions of integrated circuits to the RF front-end of wireless receivers and transmitters operating in broadcast and personal communications bands are surveyed. It is seen from this that when ICs enable a rethinking of the RF architecture, the wireless device can sometimes become significantly smaller, and consume much less power. Examples are taken from FM broadcast receivers, pagers, and

  12. Investigation of over-horizon VHF radio signals associated with earthquakes

    Microsoft Academic Search

    Y. Fukumoto; M. Hayakawa; H. Yasuda

    2001-01-01

    This paper presents the preliminary results on the possible reception of over-horizon VHF radio signals from a FM (frequency modulation) transmitter during abnormal situations (probably in close association with earthquakes). The transmitter is FM Sendai (frequency = 77.1 MHz) and the receiving station is our university (UEC) at Chofu, Tokyo, with the transmitter-receiver distance being about 310 km. We first

  13. Investigation on the Frequency Allocation for Radio Astronomy at the L Band

    NASA Astrophysics Data System (ADS)

    Abidin, Z. Z.; Umar, R.; Ibrahim, Z. A.; Rosli, Z.; Asanok, K.; Gasiprong, N.

    2013-09-01

    In this paper, the frequency allocation reserved for radio astronomy in the L band set by the International Telecommunication Union (ITU), which is between 1400 and 1427 MHz, is reviewed. We argue that the nearby frequencies are still very important for radio astronomers on the ground by investigating radio objects (H i sources) around 1300-1500 MHz. The L-band window is separated into a group of four windows, namely 1400-1427 MHz (window A), 1380-1400 MHz (window B), 1350-1380 MHz (window C), and 1300-1350 MHz (window D). These windows are selected according to their redshifts from a rest frequency for hydrogen spectral line at 1420.4057 MHz. Radio objects up to z ? 0.1 or frequency down to 1300 MHz are examined. We argue that since window B has important radio objects within the four windows, this window should also be given to radio astronomy. They are galaxies, spiral galaxies, and galaxy clusters. This underlines the significance of window B for radio astronomers on the ground. By investigating the severeness of radio frequency interference (RFI) within these windows, we have determined that window B still has significant, consistent RFI. The main RFI sources in the four windows have also been identified. We also found that the Department of Civil Aviation of Malaysia is assigned a frequency range of 1215-1427 MHz, which is transmitted within the four windows and inside the protected frequency for radio astronomy. We also investigated the RFI in the four windows on proposed sites of future radio astronomy observatories in Malaysia and Thailand and found the two best sites as Universiti Pendidikan Sultan Idris (UPSI) and Ubon Ratchathani, respectively. It has also been determined that RFI in window B increases with population density.

  14. An in situ measurement of the radio-frequency attenuation in ice at Summit Station, Greenland

    E-print Network

    J. Avva; J. M. Kovac; C. Miki; D. Saltzberg; A. G. Vieregg

    2014-09-30

    We report an in situ measurement of the electric field attenuation length at radio frequencies for the bulk ice at Summit Station, Greenland, made by broadcasting radio-frequency signals vertically through the ice and measuring the relative power in the return ground bounce signal. We find the depth-averaged field attenuation length to be 947 +92/-85 meters at 75 MHz. While this measurement has clear radioglaciological applications, the radio clarity of the ice also has implications for the detection of ultra-high energy (UHE) astrophysical particles via their radio emission in dielectric media such as ice. The measured attenuation length at Summit Station is comparable to previously measured radio-frequency attenuation lengths at candidate particle detector sites around the world, and strengthens the case for Summit Station as the most promising northern site for UHE neutrino detection.

  15. Effect of driving frequency on plasma property in radio frequency and very high frequency magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Huang, Fupei; Ye, Chao; He, Haijie; Liu, Yi; Wang, Xiangying; Ning, Zhaoyuan

    2014-02-01

    Ion energy distributions (IEDs), electron energy distributions (EEDs) and other plasma parameters of magnetron sputtering discharges driven by 13.56, 27.12 and 60 MHz sources were investigated by a retarding field energy analyzer and Langmuir probe measurements. An increase in driving frequency leads to an increase in ion energy and the evolution of IEDs from a uni-modal distribution at the 13.56 MHz discharge toward a bi-modal distribution at 27.12 MHz, and a multi-modal distribution at the 60 MHz discharge. For IEDs near the target surface, this evolution is related to the ion acceleration and the charge transfer collisions between Ar atoms and Ar+ ions in the presheath, while for IEDs at the substrate, the evolution depends on the ratio of the ion transit time across the sheath to the radio frequency period. The increase in driving frequency also leads to the evolution of EED function from a Maxwellian type at the 13.56 MHz discharge toward a bi-Maxwellian type at the 27.12 MHz discharge and a Druyvesteyn-like type at the 60 MHz discharge due to the change in the generation and loss mechanisms of electrons. In addition, increasing the driving frequency can lead to a higher electron temperature and a lower electron density. Therefore, the driving frequency becomes an effective tool to control the plasma properties of magnetron sputtering discharges.

  16. Routing in frequency-hop packet radio networks with partial-band jamming

    Microsoft Academic Search

    Michael B. Pursley; Harlan B. Russell

    1993-01-01

    Research in adaptive, decentralized routing for frequency-hop packet radio networks with mobile partial-band jamming. A routing technique called least-resistance routing (LRR) is developed, and various versions of this routing method are examined. LRR uses a quantitative assessment of the interference environment experienced by a radio's receiver to determine a resistance value for that radio. Two components for the interference environment

  17. Routing in frequency-hop packet radio networks with partial-band jamming

    Microsoft Academic Search

    M. B. Pursley; H. B. Russell

    1990-01-01

    Describes research in adaptive, decentralized routing for frequency-hop packet radio networks with mobile partial-band jamming. A new routing technique, called least-resistance routing (LRR) is developed, and various versions of this routing method are examined. LRR uses a quantitative assessment of the interference environment at a radio to determine a resistance for that radio. This resistance is a measure of the

  18. Routing in frequency-hop packet radio networks with partial-band jamming

    Microsoft Academic Search

    Michael B. Pursley; Harlan B. Russell

    1993-01-01

    This paper describes research in adaptive, decentralized routing for frequency-hop packet radio networks with mobile partial-band jamming. A new routing technique, called least-resistance routing (LRR) is developed, and various versions of this routing method are examined. LRR uses a quantitative assessment of the interference environment experienced by a radio's receiver to determine a resistance value for that radio. Two components

  19. Low Frequency Radio Observations of Interactions in Cooling Core Clusters

    Microsoft Academic Search

    T. E. Clarke; C. L. Sarazin; E. L. Blanton; N. E. Kassim; D. Neumann

    2005-01-01

    X-ray observations of the central regions of cooling core clusters have revealed a wealth of spatial detail in the thermal gas. One of the most spectacular results is the profound effect that central radio sources appear to have on the structure of the ICM. In addition to depressions associated with the active radio galaxy, there are \\

  20. Homonuclear radio frequency-driven recoupling in rotating solids Andrew E. Bennett,a)

    E-print Network

    Griffin, Robert G.

    Homonuclear radio frequency-driven recoupling in rotating solids Andrew E. Bennett,a) Chad M-labeled sample of the tetrapeptide achatin-II Gly-L-Phe-L-Ala-L-Asp . In addition, a frequency-selective approach difference between two spins matches a multiple of the spin- ning frequency, m r .12­14 Rotational resonance

  1. Quasilinear theory of collisionless electron heating in radio frequency gas discharges

    E-print Network

    Kaganovich, Igor

    Quasilinear theory of collisionless electron heating in radio frequency gas discharges Yu. M. Aliev confinement. Plasma heating by direct current and external high frequency electric fields was also, the effective frequency of electron scatter- ing becomes larger than the usual particle­particle collision

  2. Scattering of radio frequency waves by blobs in tokamak plasmas

    SciTech Connect

    Ram, Abhay K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hizanidis, Kyriakos; Kominis, Yannis [School of Electrical and Computer Engineering, National Technical University of Athens, Association EURATOM-Hellenic Republic, Athens, GR-15773 (Greece)] [School of Electrical and Computer Engineering, National Technical University of Athens, Association EURATOM-Hellenic Republic, Athens, GR-15773 (Greece)

    2013-05-15

    The density fluctuations and blobs present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction, reflection, diffraction, and coupling to other plasma waves. This, in turn, affects the spectrum of the RF waves and the electromagnetic power that reaches the core of the plasma. The usual geometric optics analysis of RF scattering by density blobs accounts for only refractive effects. It is valid when the amplitude of the fluctuations is small, of the order of 10%, compared to the background density. In experiments, density fluctuations with much larger amplitudes are routinely observed, so that a more general treatment of the scattering process is needed. In this paper, a full-wave model for the scattering of RF waves by a blob is developed. The full-wave approach extends the range of validity well beyond that of geometric optics; however, it is theoretically and computationally much more challenging. The theoretical procedure, although similar to that followed for the Mie solution of Maxwell's equations, is generalized to plasmas in a magnetic field. Besides diffraction and reflection, the model includes coupling to a different plasma wave than the one imposed by the external antenna structure. In the model, it is assumed that the RF waves interact with a spherical blob. The plasma inside and around the blob is cold, homogeneous, and imbedded in a uniform magnetic field. After formulating the complete analytical theory, the effect of the blob on short wavelength electron cyclotron waves and longer wavelength lower hybrid waves is studied numerically.

  3. Radio frequency needle hyperthermia of normal and cancerous animal tissue

    NASA Astrophysics Data System (ADS)

    Shalhav, Arieh; Ramon, J.; Goldwasser, Benad; Nativ, Ofer; Cherniack, Ramy; Zajdel, Liliana

    1994-12-01

    Capacitative radio frequency (RF) was met with little success when used to treat human cancer. Conductive rf needle hyperthermia (RFNH) is used successfully for human tissue ablation in neurosurgery, cardiology, and recently in urology. RFNH ablates tissue by causing thermal damage limited to the vicinity of the rf needle. We conducted a series of studies to evaluate the effect of RFNH on cancerous and normal tissue. RFNH was applied to normal porcine livers during open surgery. Liver function tests were elevated two days post treatment, then returned to normal. Pigs were sequentially sacrificed. RFNH induced lesions were found to be maximal in size on days 2 - 4 post treatment and later became smaller as liver regenerated. Phase 2 included mice bearing two subcutaneous murine bladder tumors (MBT2). The rf needle was inserted into both tumors of each mouse, but rf current was applied to one tumor only. Energies of 3 to 7.5 watts were applied for 30 seconds to 5 minutes using a 0.02 inch needle. Mice were sacrificed 0, 1, and 3 days after treatment. Necrotic lesions 0.5 - 1.2 cm in diameter were found within the treated tumors. In phase 3, mice bearing a single 8 - 18 mm subcutaneous tumor were treated by RFNH aiming for complete tumor destruction. All control mice died of huge tumors within 31 days. Treated mice were alive with no signs of tumor when sacrificed 60 days after treatment. In phase 3 RFNH is capable of complete tumor eradication with little damage to surrounding normal tissue. It may have clinical applications for percutaneous endoscopic and laparoscopic treatment of tumors.

  4. H- radio frequency source development at the Spallation Neutron Sourcea)

    NASA Astrophysics Data System (ADS)

    Welton, R. F.; Dudnikov, V. G.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P.; Turvey, M. W.

    2012-02-01

    The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent ˜38 mA peak current in the linac and an availability of ˜90%. H- beam pulses (˜1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, ˜60 kW) of a copper antenna that has been encased with a thickness of ˜0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of ˜99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of ˜75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to ˜100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

  5. Thermal epiphysiodesis performed with radio frequency in a porcine model

    PubMed Central

    Shiguetomi-Medina, Juan M; Rahbek, Ole; Abood, Ahmed Abdul-Hussein; Stødkilde-Jørgensen, Hans; Møller-Madsen, Bjarne

    2014-01-01

    Background and purpose Current techniques for epiphysiodesis involve opening of cortical windows; use of staples, screws, and tension devices; and fusion with curettes or drills. Complications may have serious consequences. There is a need for a more reliable, precise, and less traumatic procedure that overcomes the known complications from existing techniques. We analyzed a new epiphysiodesis technique using radio-frequency ablation (RFA) in a porcine model. Methods Six 35-kg and two 25-kg immature pigs were used. 1 hind leg of each animal was randomly selected and the proximal tibia growth plate was ablated laterally and medially. The contralateral leg was used as a control. MR images were obtained immediately after the ablation and 12 weeks later for 6 animals, and 24 weeks later for the other 2 animals. CT was done for the 2 animals that were followed for 24 weeks for proof of bone bridges. Results Both tibias were equal in length initially. At the 12-week follow-up, there was an average leg length discrepancy of 3.9 mm (95% CI: 3.0–4.8), and at 24 weeks the difference was 8.4 mm and 7.5 mm. No damage to the adjacent tissue was found. Bone bridges and physeal closure were found after 24 weeks. The pigs showed no discomfort after the intervention. Interpretation We found RFA to be feasible for epiphysiodesis in a pig model. The method is minimally invasive and recovery may be quick compared to conventional methods. We recommend that the method should be tested in larger-scale safety studies before clinical application. PMID:25036720

  6. Radio-Frequency Plasma Cleaning of a Penning Malmberg Trap

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III; Martin, James; Pearson, J. Boise; Lewis, Raymond

    2005-01-01

    Radio-frequency-generated plasma has been demonstrated to be a promising means of cleaning the interior surfaces of a Penning-Malmberg trap that is used in experiments on the confinement of antimatter. {Such a trap was reported in Modified Penning-Malmberg Trap for Storing Antiprotons (MFS-31780), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 66.} Cleaning of the interior surfaces is necessary to minimize numbers of contaminant atoms and molecules, which reduce confinement times by engaging in matter/antimatter-annihilation reactions with confined antimatter particles. A modified Penning-Malmberg trap like the one described in the cited prior article includes several collinear ring electrodes (some of which are segmented) inside a tubular vacuum chamber, as illustrated in Figure 1. During operation of the trap, a small cloud of charged antiparticles (e.g., antiprotons or positrons) is confined to a spheroidal central region by means of a magnetic field in combination with DC and radiofrequency (RF) electric fields applied via the electrodes. In the present developmental method of cleaning by use of RF-generated plasma, one evacuates the vacuum chamber, backfills the chamber with hydrogen at a suitable low pressure, and uses an RF-signal generator and baluns to apply RF voltages to the ring electrodes. Each ring is excited in the polarity opposite that of the adjacent ring. The electric field generated by the RF signal creates a discharge in the low-pressure gas. The RF power and gas pressure are adjusted so that the plasma generated in the discharge (see Figure 2) physically and chemically attacks any solid, liquid, and gaseous contaminant layers on the electrode surfaces. The products of the physical and chemical cleaning reactions are gaseous and are removed by the vacuum pumps.

  7. Modified transmitter attachment method for adult ducks

    USGS Publications Warehouse

    Pietz, P.J.; Brandt, D.A.; Krapu, G.L.; Buhl, D.A.

    1995-01-01

    The value of radio telemetry for waterfowl research depends on the availability of suitable methods of attaching transmitters. In previous studies, external transmitters attached to adult Mallards (Anas platyrhynchos) with sutures and glue did not stay on birds reliably. In an attempt to improve transmitter retention, a method of attachment was tested in which 4-g transmitters were attached mid-dorsally with sutures and with a stainless steel anchor-shaped wire inserted subcutaneously (anchor transmitters). Field tests indicated that all of 26 female Mallards and 63 of 65 female Gadwalls (Anas strepera) retained their anchor transmitters during 4369 bird-days of monitoring during nesting and brood rearing. Survival rates of females with anchor transmitters compared favorably with those reported from other studies. In this study, females with and without anchor transmitters did not differ with respect to survival rates of their ducklings. The anchor transmitter may be suitable for a variety of field studies on numerous species.

  8. Sleep EEG alterations: effects of pulsed magnetic fields versus pulse-modulated radio frequency electromagnetic fields.

    PubMed

    Schmid, Marc R; Murbach, Manuel; Lustenberger, Caroline; Maire, Micheline; Kuster, Niels; Achermann, Peter; Loughran, Sarah P

    2012-12-01

    Studies have repeatedly shown that electroencephalographic power during sleep is enhanced in the spindle frequency range following radio frequency electromagnetic field exposures pulse-modulated with fundamental frequency components of 2, 8, 14 or 217 Hz and combinations of these. However, signals used in previous studies also had significant harmonic components above 20 Hz. The current study aimed: (i) to determine if modulation components above 20 Hz, in combination with radio frequency, are necessary to alter the electroencephalogram; and (ii) to test the demodulation hypothesis, if the same effects occur after magnetic field exposure with the same pulse sequence used in the pulse-modulated radio frequency exposure. In a randomized double-blind crossover design, 25 young healthy men were exposed at weekly intervals to three different conditions for 30 min before sleep. Cognitive tasks were also performed during exposure. The conditions were a 2-Hz pulse-modulated radio frequency field, a 2-Hz pulsed magnetic field, and sham. Radio frequency exposure increased electroencephalogram power in the spindle frequency range. Furthermore, delta and theta activity (non-rapid eye movement sleep), and alpha and delta activity (rapid eye movement sleep) were affected following both exposure conditions. No effect on sleep architecture and no clear impact of exposure on cognition was observed. These results demonstrate that both pulse-modulated radio frequency and pulsed magnetic fields affect brain physiology, and the presence of significant frequency components above 20 Hz are not fundamental for these effects to occur. Because responses were not identical for all exposures, the study does not support the hypothesis that effects of radio frequency exposure are based on demodulation of the signal only. PMID:22724534

  9. Analytical model for the radio-frequency sheath.

    PubMed

    Czarnetzki, Uwe

    2013-12-01

    A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary symmetry. The externally applied rf voltage is assumed to be sinusoidal, although the model can be extended to arbitrary wave forms, e.g., for dual-frequency discharges. The model calculates explicitly the cubic correction parameter in the charge-voltage relation for the case of highly asymmetric discharges. It is shown that the cubic correction is generally moderate but more pronounced in the collisionless case. The analytical results are compared to experimental data from the literature obtained by laser electric field measurements of the mean and dynamic fields in the capacitive sheath for various gases and pressures. Very good agreement is found throughout. PMID:24483571

  10. Calculus, Radio Dials and the Straight-Line Frequency Variable Capacitor

    ERIC Educational Resources Information Center

    Boyadzhiev, Khristo N.

    2010-01-01

    Most often radio dials of analogue radios are not uniformly graded; the frequencies are cramped on the left side or on the right side. This makes tuning more difficult. Why are dials made this way? We shall see here that simple calculus can help understand this problem and solve it. (Contains 7 figures.)

  11. PHOTONIC SYNTHESIS AND HARDWARE CORRELATIONS OF ULTRABROADBAND RADIO-FREQUENCY WAVEFORMS AND POWER

    E-print Network

    Purdue University

    PHOTONIC SYNTHESIS AND HARDWARE CORRELATIONS OF ULTRABROADBAND RADIO-FREQUENCY WAVEFORMS AND POWER Purdue University West Lafayette, Indiana #12;ii This thesis is dedicated to my Father Tsing-Fa Lin who.....................................10 2.4.1 Introduction to Ultra-Wide Bandwidth Impulse Radio

  12. Design of radio frequency energy harvesting system for an unmanned airplane

    Microsoft Academic Search

    Wei Zhao; Kwangsik Choi; Zeynep Dilli; Scott Bauman; Thomas Salter; Martin Peckerar

    2011-01-01

    Energy harvesting is a promising technique that can be used to drive various sorts of passively powered devices [1]. Viable energy sources include wind, sunlight, thermal energy, radio waves, mechanical vibration and so on. As an energy source existing ubiquitously in our environment, radio frequency (RF) energy harvesting has the potential to be widely applied. In this work, an RF

  13. Supporting the ILWS Program with the New Capabilities of Emerging Low-Frequency Radio Arrays

    Microsoft Academic Search

    J. Kasper; D. Oberoi; M. Morales; A. Lazarus; C. Lonsdale; J. Salah; R. Capallo; M. Bird

    2004-01-01

    The recent pace of advancements in computational power and network capacity will soon usher in a new era for radio astronomy in the form of next generation, low-frequency, digital aperture synthesis radio interferometers. In a digital array, the signals from each antenna are digitized and sent to a central processing facility for simultaneous aperture synthesis in multiple directions whose number

  14. Preliminary analysis of investigation Radio Frequency Interference (RFI) profile analysis at Universiti Teknologi MARA

    Microsoft Academic Search

    Z. S. Hamidi; Z. Z. Abidin; Z. A. Ibrahim; N. N. M. Shariff; Ungku Ferwani Salwa Ungku Ibrahim; R. Umar

    2011-01-01

    In this paper, we have identified some important Radio Frequency Interference (RFI) sources that can potentially be a problem for any future radio astronomical observations in Universiti Teknologi MARA (UiTM) and possibly in Malaysia as a whole. Analysis is done by classifying and characterizing the strength of the sources' RFI profiles. Comparison of the RFI profiles between the indoor (Faculty

  15. 1\\TM-1074 I ASE GRENADE TRANSMITTER

    E-print Network

    Rathbun, Julie A.

    1\\TM-1074 I ASE GRENADE TRANSMITTER FREQUENCY DRIFT 01' zo DAiE 19 Nov 197 1 This ATM provides a projection of the maximum frequency of the Flight 5 and Spare ASE grenade transmitters up to 6 years from transmitter acceptance testing. This projection is based on recent KSC test results and provides assurance

  16. Two signaling schemes for improving the error performance of frequency-division-duplex (FDD) transmission systems using transmitter antenna diversity

    Microsoft Academic Search

    N. Seshadri; Jack H. Winters

    1993-01-01

    Two signaling schemes that exploit the availability of multiple (N) antennas at the transmitter to provide diversity benefit to the receiver are proposed. In the first scheme, a channel code of length N and minimum Hamming distance dmin ⩽ N is used to encode a group of K information bits. The channel code symbol ci is transmitted with the ith

  17. Laparoscopic Application Of Radio Frequency Energy Enables In Situ Renal Tumor Ablation And Partial Nephrectomy

    Microsoft Academic Search

    LUCAS JACOMIDES; KENNETH OGAN; LORI WATUMULL; JEFFREY A. CADEDDU

    2003-01-01

    PurposeTo our knowledge we present the initial series of renal mass in situ laparoscopic radio frequency ablation. We also discuss the indications for and results of subsequent laparoscopic partial nephrectomy.

  18. Radio Frequency Hearing Aids: The Need for Complementary and Compatible Channel Allocation.

    ERIC Educational Resources Information Center

    Burgess, Vic; And Others

    1979-01-01

    The article discusses the use of radio frequency hearing aids, which provide a practical means of improving the signal-to-noise ratio of conventional hearing aids used by the aurally handicapped. (Author/DLS)

  19. Impedance matching and DC-DC converter designs for tunable radio frequency based mobile telecommunication systems 

    E-print Network

    Wong, Yan Chiew

    2014-06-30

    Tunability and adaptability for radio frequency (RF) front-ends are highly desirable because they not only enhance functionality and performance but also reduce the circuit size and cost. This thesis presents a number ...

  20. 75 FR 54790 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-09

    ...requesting use of the radio frequency spectrum. DATES: Effective Date: This regulation...effect, is available in the Office of Spectrum Management, 1401 Constitution Avenue...CONTACT: William Mitchell, Office of Spectrum Management at (202) 482-8124 or...