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1

75. Transmitter building no. 102, view of typical radio frequency ...  

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

75. Transmitter building no. 102, view of typical radio frequency switching group for lower antenna A & B and upper antenna A & B and MIP/MWOC automated interface cabinet. - 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

2

Radio frequency radiation (RFR) from TV and radio transmitters at a pilot region in Turkey.  

PubMed

For the last 30 y, the biological effects of non-ionising radiation (NIR: 0-300 GHz) have been a major topic in bioelectromagnetism. Since the number of radiofrequency (RF) systems operating in this frequency range has shown an incredible increase over the last few decades, the dangers of exposure to the fields generated thereby has become an important public health issue. In this study, the aim was to evaluate the level of RF electromagnetic radiation in Yenimahalle Sentepe Dededoruk Hill in Ankara, Turkey that is a multiple-transmitter site hosting 64 different TV and radio towers and one base station for mobile phone communication. The site has been of interest as it is nearby a residential community. Within the technical input data available on 31 of the radio and TV transmitters, the calculated radiation level in this particular region was found to be approximately four times higher than the permitted standards of Turkey, which are the same as the ICNIRP standards. Electromagnetic field measurement is needed in the site. PMID:19671591

Sirav, Bahriye; Seyhan, Nesrin

2009-09-01

3

Impact of Mobile Transmitter Sources on Radio Frequency Wireless Energy Harvesting  

E-print Network

1 Impact of Mobile Transmitter Sources on Radio Frequency Wireless Energy Harvesting Antonio work that investigates the impact of energy transfer, especially concerning the energy gain, and possibly ambient sources of energy, such as the sun, wind, naturally occurring vibrations, among others

Sanyal, Sugata

4

Micro-miniature radio frequency transmitter for communication and tracking applications  

SciTech Connect

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.

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

5

System efficiency analysis for high power solid state radio frequency transmitter  

SciTech Connect

This paper examines some important relationships, related with the system efficiency, for very high power, radio frequency solid-state transmitter; incorporating multiple solid-state power amplifier modules, power combiners, dividers, couplers, and control/interlock hardware. In particular, the characterization of such transmitters, at the component as well as the system level, is discussed. The analysis for studying the influence of the amplitude and phase imbalance, on useful performance parameters like system efficiency and power distribution is performed. This analysis is based on a scattering parameter model. This model serves as a template for fine-tuning the results, with the help of a system level simulator. For experimental study, this approach is applied to a recently designed modular and scalable solid-state transmitter, operating at the centre frequency of 505.8?MHz and capable of delivering a continuous power of 75 kW. Such first time presented, system level study and experimental characterization for the real time operation will be useful for the high power solid-state amplifier designs, deployed in particle accelerators.

Jain, Akhilesh, E-mail: ajain@rrcat.gov.in; Sharma, D. K.; Gupta, A. K.; Lad, M. R.; Hannurkar, P. R. [RF Systems Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)] [RF Systems Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Pathak, S. K. [Electromagnetics and Microwave Engineering, Institute for Plasma Research, Gandhinagar 382 428 (India)] [Electromagnetics and Microwave Engineering, Institute for Plasma Research, Gandhinagar 382 428 (India)

2014-02-15

6

System efficiency analysis for high power solid state radio frequency transmitter  

NASA Astrophysics Data System (ADS)

This paper examines some important relationships, related with the system efficiency, for very high power, radio frequency solid-state transmitter; incorporating multiple solid-state power amplifier modules, power combiners, dividers, couplers, and control/interlock hardware. In particular, the characterization of such transmitters, at the component as well as the system level, is discussed. The analysis for studying the influence of the amplitude and phase imbalance, on useful performance parameters like system efficiency and power distribution is performed. This analysis is based on a scattering parameter model. This model serves as a template for fine-tuning the results, with the help of a system level simulator. For experimental study, this approach is applied to a recently designed modular and scalable solid-state transmitter, operating at the centre frequency of 505.8 MHz and capable of delivering a continuous power of 75 kW. Such first time presented, system level study and experimental characterization for the real time operation will be useful for the high power solid-state amplifier designs, deployed in particle accelerators.

Jain, Akhilesh; Sharma, D. K.; Gupta, A. K.; Lad, M. R.; Hannurkar, P. R.; Pathak, S. K.

2014-02-01

7

SHIELDED-NEEDLE TECHNIQUE FOR SURGICALLY IMPLANTING RADIO-FREQUENCY TRANSMITTERS IN FISH  

EPA Science Inventory

Protruding whip antenna radio transmitters were implanted in fish with abdominal pelvic fins. This surgical technique enables the transmitter to be positioned anywhere in the peritoneal cavity without piercing vital organs through the use of a shielded needle to guide an antenna ...

8

Radio frequency detection assembly and method for detecting radio frequencies  

DOEpatents

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.

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

2010-03-16

9

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...

10

TAIL-MOUNTED RADIO TRANSMITTERS FOR WATERFOWL  

Microsoft Academic Search

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

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

11

EFFECTS OF RADIO TRANSMITTERS ON MIGRATING  

Microsoft Academic Search

We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of wood thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores.

LARKIN A. POWELL; DAVID G. KREMENTZ; JASON D. LANG; MICHAEL J. CONROY

12

A radio transmitter attachment technique for soras  

USGS Publications Warehouse

We modified a figure-8 leg-loop harness designed for small passerines to attach successfully 1.8-g radio transmitters over the synsacrum of migrant Soras (Porzana carolina). Because of the short caudal region of Soras, addition of a waist loop was critical to securing the transmitter while leg loops were maintained to center the package. Thin gauge (0.6-mm diameter) elastic thread proved ideal for transmitter attachment and allowed for freedom of movement and girth expansion associated with fattening during a 6-10 week stopover. Of 110 Soras radio tagged during three field seasons, only a single mortality was observed and only a single bird lost its transmitter. Migration from the study area was confirmed for 76 (69%) and suspected for another 25 birds (total 92%).

Haramis, G.M.; Kearns, G.D.

2000-01-01

13

Implanting radio transmitters in wintering canvasbacks  

USGS Publications Warehouse

To conduct telemetry studies of wintering canvasbacks (Aythya valisineria) on Chesapeake Bay [Maryland, USA], we needed to devise a suitable method of radio transmitter attachment. We describe as aseptic, intraabdominal surgical technique, using the inhalation anesthetic isoflurane, to implant 20-g radio transmitters in free-ranging canvasbacks. We evaluated the technique over 3 winters (1987-89), when an annual average of 83 female canvasbacks received implant surgery during a 9-day period in mid-December. Of 253 ducks, 248 (98%) were implanted successfully, and 200 (80.65) completed the 70-day study until early March. No mortality or abnormal behavior from surgery was identified post-release.

Olsen, G.H.; Dein, F.J.; Haramis, G.M.; Jorde, D.G.

1992-01-01

14

Implanting radio transmitters in wintering canvasbacks  

USGS Publications Warehouse

To conduct telemetry studies of wintering canvasbacks (Aythya valisineria) on Chesapeake Bay, we needed to devise a suitable method of radio transmitter attachment. We describe an aseptic, intra-abdominal surgical technique, using the inhalation anesthetic isoflurane, to implant 20-g radio transmitters in free-ranging canvasbacks. We evaluated the technique over 3 winters (1987-89), when an annual average of 83 female canvasbacks received implant surgery during a 9-day period in mid-December. Of 253 ducks, 248 (98%) were implanted successfully, and 200 (80.6%) completed the 70-day study until early March. No mortality or abnormal behavior from surgery was identified post-release.

Olsen, G.H.; Dein, F.J.; Haramis, G.M.; Jorde, D.G.

1992-01-01

15

Effects of external radio transmitters on fish  

SciTech Connect

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.

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

1981-04-01

16

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

PubMed

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

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

17

DQPSK Receiver tolerance to transmitter frequency stability  

Microsoft Academic Search

In case of Differential Quadrature Phase Shift Keying transmission, the diode laser frequency instability affects the quality of the received signal. Free-running transmitters are employed to experimentally evaluate the tolerance of the interferometric DQPSK receiver to this instability. Heterodyne measure of the frequency offset is discussed for different transmitters. Experimental data are related both with BER performance and power penalty.

Lucia Marazzi; Paola Parolari; Pierpaolo Boffi; Rocco Siano; Matteo Feroldi; M. Martinelli

2006-01-01

18

Effects of implanted radio transmitters with percutaneous antennas on the behavior of Canada Geese  

USGS Publications Warehouse

We examined whether surgically-implanted radio transmitters with percutaneous antennas affected behavior of Lesser Canada Geese (Branta canadensis parvipes) in Anchorage, Alaska. We implanted either a 26-g VHF radio transmitter or a larger VHF radio that was the same mass (35 g) and shape as a satellite transmitter in the coelom of adult females captured during molt in 2000. A control group of females was marked with leg bands. We simultaneously observed behavior of radio-marked and control females from 4-62 d following capture. We observed no differences in the proportion of time birds in different treatments allocated among grazing, resting, comfort, walking, and alert behavior. Females in different treatments spent a similar proportion of time in the water. Implantation of radio transmitters did not affect the frequency of agonistic interactions. We conclude that coelomic radio transmitters with percutaneous antennas had minimal effects on the behavior of Canada Geese.

Hupp, J.W.; Ruhl, G.A.; Pearce, J.M.; Mulcahy, D.M.; Tomeo, M.A.

2003-01-01

19

47 CFR 95.625 - CB transmitter channel frequencies.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false CB transmitter channel frequencies. 95.625 Section 95.625...Technical Standards § 95.625 CB transmitter channel frequencies. (a) The CB transmitter channel frequencies are: Channel No....

2010-10-01

20

47 CFR 95.625 - CB transmitter channel frequencies.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false CB transmitter channel frequencies. 95.625 Section 95.625...Technical Standards § 95.625 CB transmitter channel frequencies. (a) The CB transmitter channel frequencies are: Channel No....

2011-10-01

21

47 CFR 95.625 - CB transmitter channel frequencies.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false CB transmitter channel frequencies. 95.625 Section 95.625...Technical Standards § 95.625 CB transmitter channel frequencies. (a) The CB transmitter channel frequencies are: Channel No....

2012-10-01

22

47 CFR 95.625 - CB transmitter channel frequencies.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false CB transmitter channel frequencies. 95.625 Section 95.625...Technical Standards § 95.625 CB transmitter channel frequencies. (a) The CB transmitter channel frequencies are: Channel No....

2013-10-01

23

1. VIEW TO NORTHWEST WITH RADIO CONTROL HOUSE (RIGHT), TRANSMITTER ...  

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

1. VIEW TO NORTHWEST WITH RADIO CONTROL HOUSE (RIGHT), TRANSMITTER TOWER (CENTER), AND NORTH BREAKWATER LIGHT IN DISTANCE AT LEFT - Frankfort Coast Guard Station, Radio Control House, Second Street at ship channel, Frankfort, Benzie County, MI

24

Solar radio-transmitters on snail kites in Florida  

USGS Publications Warehouse

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.

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

1989-01-01

25

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...

2009-10-12

26

Effects of radio transmitters on migrating wood thrushes  

USGS Publications Warehouse

We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of Wood Thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores. We used two strengths of line, 5- and 9-kg test-strength braided Dacron, to attach the transmitters using the thigh-harness method. We recaptured 13 returning radio-marked Wood Thrushes, seven of which were still marked. Six of the seven birds marked with the 5-kg test harnesses lost their transmitters within 1 yr while all six of the 9-kg test harnesses were still attached up to 21 mo later. Radio-marking did not reduce the return rates of adults and immatures, and the transmitters did not cause radio-marked birds to lose more mass than banded-only birds. Wood Thrushes can successfully carry a transmitter during migration with no detectable negative effects. We recommend continued use of the thigh-harness method, but we encourage the use of 5-kg cotton line.

Powell, L.A.; Krementz, D.G.; Lang, J.D.; Conroy, M.J.

1998-01-01

27

Radio frequency pressure transducer  

Microsoft Academic Search

A novel system is reported here for the pressure measurement at microwave and millimetre-wave frequencies. This method consists in using a radio frequency transducer based on RF resonator. Accurate determination of the pressure is expected.

M. M. Jatlaoui; P. Pons; H. Aubert

2007-01-01

28

Stabilized radio frequency quadrupole  

DOEpatents

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.

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

1984-12-25

29

Stabilized radio frequency quadrupole  

DOEpatents

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.

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

1984-01-01

30

Radio Frequency Tomography for Tunnel Detection  

Microsoft Academic Search

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

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

2010-01-01

31

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. ...

32

Influence of radio transmitters on prairie falcons (Falco mexicanus)  

USGS Publications Warehouse

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.

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

1996-01-01

33

Radio frequency identification (RFID)  

Microsoft Academic Search

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

C. M. Roberts

2006-01-01

34

47 CFR 95.623 - R/C transmitter channel frequencies.  

Code of Federal Regulations, 2010 CFR

... 5 2010-10-01 2010-10-01 false R/C transmitter channel frequencies. 95.623...Regulations Technical Standards § 95.623 R/C transmitter channel frequencies. (a) The R/C transmitter channel frequencies are:...

2010-10-01

35

SECURING RADIO FREQUENCY IDENTIFICATION (RFID)  

E-print Network

May 2007 SECURING RADIO FREQUENCY IDENTIFICATION (RFID) SYSTEMS SECURING RADIO FREQUENCY IDENTIFICATION (RFID) SYSTEMS Karen Scarfone, EditorKaren Scarfone, Editor Computer Security Division of Standards and Technology National Institute of Standards and Technology RFID is a form of automatic

36

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

Microsoft Academic Search

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

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

2008-01-01

37

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

Microsoft Academic Search

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

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

38

A Radio Frequency Meteor Detector  

NASA Astrophysics Data System (ADS)

We report on the development of a radio/computer system for monitoring meteor activity. The radio receiver is tuned to a commercial television transmitter located beyond the local horizon, so that the system is normally unable to detect a signal. When a meteor enters the atmosphere between the transmitter and receiver it creates an ion trail which can reflect some power between them. We have interfaced the radio's automatic gain control voltage to a personal computer by means of an analog-to-digitial board. The computer is programmed to save 5 seconds of 20 Hz data whenever the signal jumps by 4 db or more. Since false triggering can be a problem, our software checks for the most common types of false positives: airplane reflections and sudden electrical impulses. Numerous meteor echos have been obtained, and are being analyzed. We plan to monitor this activity for one year, and relate the observations to the rate of meteoroids entering the atmosphere.

Mallama, A.; Espenak, F.; Mobile, R.

1996-09-01

39

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

Microsoft Academic Search

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

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

1996-01-01

40

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...

41

Radio frequency coaxial feedthrough  

DOEpatents

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.

Owens, Thomas L. (Kingston, TN)

1989-01-17

42

Stabilized radio-frequency quadrupole  

DOEpatents

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.

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

1982-09-29

43

Effects of antenna length and material on output power and detection of miniature radio transmitters  

USGS Publications Warehouse

The optimal antenna of transmitters used in small aquatic animals is often a compromise between efficient radio wave propagation and effects on animal behavior. Radio transmission efficiency generally increases with diameter and length of the conductor, but increased antenna length or weight can adversely affect animal behavior. We evaluated the effects of changing antenna length and material on the subsequent tag output power, reception, and detection of tagged fish. In a laboratory, we compared the relative signal strengths in water of 150 MHz transmitters over a range of antenna lengths (from 6 to 30 cm) and materials (one weighing about half of the other). The peak relative signal strengths were at 20 and 22 cm, which are approximately one wavelength underwater at the test frequency. The peak relative signal strengths at these lengths were approximately 50% greater than those of 30 cm antennas, a length commonly used in fisheries research. Few significant differences were present in distances for the operator to hear or the telemetry receiver to decode transmitters from a boat-mounted receiving system based on antenna length, but the percent of tagged fish detected passing a hydroelectric dam fitted with an array of receiving systems was significantly greater at the antenna length with peak output power in laboratory tests. This study indicates careful choice of antenna length and material of small transmitters can be used to reduce weight and possible antenna effects on animal behavior, to maximize tag output power and detection, or to balance these factors based on the needs of the application. ?? 2007 Springer Science+Business Media B.V.

Beeman, J.W.; Bower, N.; Juhnke, S.; Dingmon, L.; Van Den, Tillaart, M.; Thomas, T.

2007-01-01

44

Low-frequency radio navigation system  

NASA Technical Reports Server (NTRS)

A method of continuous wave navigation using four transmitters operating at sufficiently low frequencies to assure essentially pure groundwave operation is described. The transmitters are keyed to transmit constant bursts (1/4 sec) in a time-multiplexed pattern with phase modulation of at least one transmitter for identification of the transmitters and with the ability to identify the absolute phase of the modulated transmitter and the ability to modulate low rate data for transmission. The transmitters are optimally positioned to provide groundwave coverage over a service region of about 50 by 50 km for the frequencies selected in the range of 200 to 500 kHz, but their locations are not critical because of the beneficial effect of overdetermination of position of a receiver made possible by the fourth transmitter. Four frequencies are used, at least two of which are selected to provide optimal resolution. All transmitters are synchronized to an average phase as received by a monitor receiver.

Wallis, D. E. (inventor)

1983-01-01

45

Radio Frequency Identification  

NSDL National Science Digital Library

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.

Leske, Cavin.

46

Loss from harlequin ducks of abdominally implanted radio transmitters equipped with percutaneous antennas  

USGS Publications Warehouse

We documented extrusion and loss of abdominally implanted radio transmitters with percutaneous antennas from adult female Harlequin Ducks (Histrionicus histrionicus). Birds were captured during wing molt (late August to mid-September) in 1995-1997. Of 44 Harlequin Ducks implanted with radios and recaptured, 7 (16%) had lost their transmitters and 5 (11%) had radios in the process of extruding. Most (11 of 12) extrusions and losses occurred in birds implanted with radios in 1996 and recaptured in 1997. We suggest that transmitter extrusions and losses were due largely to changes in transmitter design made between 1095 and 1996. Transmitters implanted in 1996 were cylindrical rather than spherical, had a flat end with an abrupt edge, and the lower portion of the antenna was reinforced. Radio losses occurred after the 7-mo monitoring period and caused no apparent harm to the birds. Investigators using implanted radios with percutaneous antennas for long-term projects should be aware of the potential for radio extrusion and should minimize the problem by using transmitters that have no sharp edges and that are wide, rather than narrow.

Mulcahy, D.M.; Esler, Daniel; Stoskopf, M.K.

1999-01-01

47

Frequency Allocation; The Radio Spectrum.  

ERIC Educational Resources Information Center

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…

Federal Communications Commission, Washington, DC.

48

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

USGS Publications Warehouse

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.

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

2007-01-01

49

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

Microsoft Academic Search

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

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

2007-01-01

50

Radio Frequency Interference: Radio Astronomy's Biggest Enemy  

NASA Astrophysics Data System (ADS)

As technology progresses, the demand for the usage of the electromagnetic spectrum increases with it. The development is so fast and prolific that clean band space for passive users such as Radio Astronomy is becoming ever so scarce. Even though, several spectral bands have been protected for Radio Astronomy by Federal Communication Commission (in the USA) under the recommendations of the International Telecommunication Union (ITU), pressure for making more spectral space commercially usable is extreme. Although these commercial usages make our modern living at all possible, often the extreme vulnerability of passive users are are not fully appreciated, resulting in unwanted emissions (RFI) in the Radio Astronomy Bands. Another source of RFI is the fact that many of the electronic devices used in the observatories themselves generate radio waves. If proper precautions are not taken, these can be received back through the Radio Telescope itself. This problem is referred to as internal RFI. The focus of this paper is the search and diminution of internal RFI in the Arecibo Observatory in Arecibo, Puerto Rico. Using a simple setup of a log-periodic antenna and a Spectrum Analyzer, spectra spanning a frequency range of 100 - 1800 MHZ were recorded in some areas of the Observatory and the new Visitor Center (AOVEF). The measurements disclosed sources of radio emission among some of the digital electronic equipment in the Equipment room and a few displays in the AOVEF. Most prominent of these was a 2.5 MHz comb spanning the entire range of the measurements emitted from the SRENDIP and AOFTM machines. The respective groups were informed and corrective shielding & isolations were implemented immediately. In AOVEF, three displays, some audio-visual equipment, and video/digital cameras used by the visitors were found to be "leaky". In future, the use of such cameras will be prohibited and the exhibits will be screened appropriately.

Acevedo, F.; Ghosh, Tapasi

1997-12-01

51

Technique for Predicting the Radio Frequency Field Strength Inside an Enclosure  

NASA Technical Reports Server (NTRS)

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.

Hallett, Michael P.; Reddell, Jerry P.

1997-01-01

52

47 CFR 74.461 - Transmitter power.  

Code of Federal Regulations, 2010 CFR

...power is the power at the transmitter output terminals and delivered to the antenna, antenna transmission line, or any other impedance-matched, radio frequency load. For the purpose of this Subpart, the transmitter power is the carrier...

2010-10-01

53

ELF/VLF radio signals caused by ionospheric demodulation of MF/HF radio transmitter signals  

NASA Astrophysics Data System (ADS)

A quantitative theory of the generation of ELF/VLF signals, which are caused by the ionospheric demodulation of modulated signals from broadcasting MF/HF transmitters, is developed. Two cases are considered when the ionospheric current, modulated by broadcasting signals, is a one-dimensional linear current (the polar electrojet), and when it is an extended two-dimensional current sheet. It is shown that the main demodulation effect is caused by the formation of an ionospheric travelling wave antenna. In the case of the polar electrojet, this antenna radiates ELF/VLF waves in two directions, one of which coincides with the line connecting the broadcasting transmitter with the ELF/VLF receiver, and the other one is in a direction which is the mirror image of this line relative to the current direction. In this case the polarisation of the ELF/VLF magnetic field component varies widely. In the case of the extended ionospheric current, the demodulation takes place along the line connecting the MF/HF transmitter with the ELF/VLF receiver, and the horizontal ELF/VLF magnetic field component is normal to this line. Amplitude and phase distortions in the ELF/VLF signal are absent below a frequency <<< 1 kHz and appear above ~1 kHz. Quantitative estimates of the amplitude of the ELF/VLF signal give a value ~0.15pT which is close to the experimentally observed value.

Trakhtengerts, V. Y.; Demekhov, A. G.; Polyakov, S. V.; Manninen, J.; Turunen, T.; Rycroft, M. J.

1997-10-01

54

Effects of radio transmitters on the behavior of Red-headed Woodpeckers  

Microsoft Academic Search

ABSTRACT. Previous studies have revealed that radio-transmitters may affect bird behaviors, including feeding rates, foraging behavior, vigilance, and preening behavior. In addition, depending on the method of attachment,;\\u000atransmitters can potentially affect the ability of cavity-nesting birds to use cavities. Our objective was to evaluate effects of transmitters on the behavior of and use of cavities byRed-headedWoodpeckers (Melanerpes erythrocephalus). Using

Mark Vukovich; John C. Kilgo

2009-01-01

55

Effects of radio transmitters on the behavior of Red-headed Woodpeckers.  

SciTech Connect

ABSTRACT. Previous studies have revealed that radio-transmitters may affect bird behaviors, including feeding rates, foraging behavior, vigilance, and preening behavior. In addition, depending on the method of attachment, transmitters can potentially affect the ability of cavity-nesting birds to use cavities. Our objective was to evaluate effects of transmitters on the behavior of and use of cavities byRed-headedWoodpeckers (Melanerpes erythrocephalus). Using backpack harnesses, we attached 2.1-g transmitter packages that averaged 3.1% of body weight (range = 2.5–3.6%) to Red-headed Woodpeckers. We observed both radio-tagged (N = 23) and nonradio-tagged (N = 28) woodpeckers and determined the percentage of time spent engaged in each of five behaviors: flight, foraging, perching, preening, and territorial behavior. We found no difference between the two groups in the percentage of time engaged in each behavior. In addition, we found that transmitters had no apparent effect on use of cavities for roosting by radio-tagged woodpeckers (N = 25).We conclude that backpack transmitters weighing less than 3.6% of body weight had no impact on either their behavior or their ability to use cavities.

Vukovich, Mark; Kilgo, John, C.

2009-05-01

56

Flying radio frequency undulator  

NASA Astrophysics Data System (ADS)

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.

Kuzikov, S. V.; Savilov, A. V.; Vikharev, A. A.

2014-07-01

57

Radio Frequency Interference and the National Radio Astronomy Observatory  

NASA Astrophysics Data System (ADS)

Radio frequency interference (RFI) and radio astronomy have been closely linked since the emergence of radio astronomy as a scientific discipline in the 1930s. Even before the official establishment of the National Radio Astronomy Observatory, protection against contemporary and future radio noise levels was seen as crucial to ensure success of any new observatory. My talk will examine the various local, regional, national, and international efforts enacted to protect NRAO and other American radio astronomy sites from RFI.

Smith, Sierra

2014-01-01

58

Radio frequency coaxial feedthrough device  

DOEpatents

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.

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

59

Low Frequency Radio Experiment (LORE)  

NASA Astrophysics Data System (ADS)

High temporal and frequency resolution observations of solar generated disturbances below 15 MHz in the near-Sun region and at Sun-Earth distances in conjunction with optical and high energy observations of Sun are essential to understand the structure and evolution of eruptions, such as, flares, coronal mass ejections (CMEs), and their associated solar wind disturbances at heights above the photosphere and their consequences in the interplanetary medium. This talk presents a case study of Low Frequency Radio Experiment (LORE) payload to probe the corona and the solar disturbances at solar offsets greater than 2 solar radii below 30 MHz. The LORE, although not part of Aditya-L1 mission, can be complimentary to planned Aditya-L1 coronagraph and its other on-board payloads as well as synergistic to ground based observations, which are routinely carried out by Ooty Radio Telescope. We discuss the baseline design and technical details of the proposed LORE and it is particularly suitable for providing data on the detailed time and frequency structure of fast drifting Type-III and slow drifting Type-II radio bursts with unprecedented time and frequency resolution as well as goniopolarimetry, made possible with better designed antennas and state-of-art electronics, employing FPGAs and an intelligent data management system. This would enable wide ranging studies such as studies of nonlinear plasma processes, CME in-situ radio emission, CME driven phenomena, interplanetary CME driven shocks, ICMEs driven by decelerating IP shocks and space weather effects of Solar Wind interaction regions. The talk will highlight the science objectives as well as the proposed technical design features.

Manoharan, Periasamy K.; Joshi, Bhal Chandra; Naidu, Arun Kumar

60

Superconducting Radio-Frequency Cavities  

NASA Astrophysics Data System (ADS)

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.

Padamsee, Hasan S.

2014-10-01

61

Battery voltage variations and radio transmitter temperatures of the small spacecraft  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

62

A Radio Frequency Interference Mitigation Strategy for the Allen Telescope Array Geoffrey C. Bower  

E-print Network

and cellular phone signals below 1000 MHz, television and FM radio transmitters, microwave ovens, and a variety) at the Allen Telescope Array (ATA). Because of the unique broadband nature of the ATA, RFI is a greater problem Large Array. The ATA faces unique problems and opportunities with respect to radio frequency

Bower, Geoffrey

63

Low Radio Frequency Picosatellite Missions  

NASA Astrophysics Data System (ADS)

The dramatic advances in cubesat and other picosatellite capabilities are opening the door for scientifically important observations at low radio frequencies. Because simple antennas are effective at low frequencies, and receiver technology allows low mass and low power instruments, these observations are an ideal match for very small spacecraft. A workshop on cubesat missions for low frequency radio astronomy was held at the Kiss Institute for Space Sciences, Caltech, to explore mission concepts involving one up to hundreds of picosatellites. One result from this workshop was that there are opportunities for viable missions throughout this large range. For example, the sky-integrated spectral signature of highly redshifted neutral hydrogen from the dark ages and cosmic dawn epochs can be measured by a single antenna on a single spacecraft. There are challenging issues of calibration, foreground removal, and RF interference that need to be solved, but the basic concept is appealingly simple. At the other extreme, imaging of angular structure in the high-redshift hydrogen signal will require an interferometer array with a very large number of antennas. In this case the primary requirement is a sufficiently low individual spacecraft mass that hundreds can be launched affordably. The technical challenges for large arrays are long-term relative station keeping and high downlink data rates. Missions using several to a few tens of picosatellites can image and track bright sources such as solar and planetary radio bursts, and will provide essential validation of technologies needed for much larger arrays.This work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Jones, Dayton L.

2014-06-01

64

47 CFR 80.209 - Transmitter frequency tolerances.  

Code of Federal Regulations, 2011 CFR

... For narrow-band direct printing and data emissions 10 Hz. 2 For digital selective calling emissions 10 Hz. For Morse telegraphy emissions 10. For all other emissions 15 Hz. (ii) Ship stations: For transmitters with...

2011-10-01

65

47 CFR 80.209 - Transmitter frequency tolerances.  

Code of Federal Regulations, 2013 CFR

... For narrow-band direct printing and data emissions 10 Hz. 2 For digital selective calling emissions 10 Hz. For Morse telegraphy emissions 10. For all other emissions 15 Hz. (ii) Ship stations: For transmitters with...

2013-10-01

66

47 CFR 80.209 - Transmitter frequency tolerances.  

Code of Federal Regulations, 2012 CFR

... For narrow-band direct printing and data emissions 10 Hz. 2 For digital selective calling emissions 10 Hz. For Morse telegraphy emissions 10. For all other emissions 15 Hz. (ii) Ship stations: For transmitters with...

2012-10-01

67

47 CFR 95.628 - MedRadio transmitters.  

Code of Federal Regulations, 2010 CFR

...associated with medical body-worn devices, regardless...a frequency monitoring system as set forth in paragraph...intended to be implanted in a human body, radiated emissions and...a Commission-approved human body simulator and test...

2010-10-01

68

47 CFR 95.628 - MedRadio transmitters.  

Code of Federal Regulations, 2011 CFR

...associated with medical body-worn devices, regardless...a frequency monitoring system as set forth in paragraph...intended to be implanted in a human body, radiated emissions and...a Commission-approved human body simulator and test...

2011-10-01

69

Frequency of occurrence of transmittance in several wavelength regions during a 3-year period.  

PubMed

Within the framework of the OPAQUE project the transmittances in the visible, the far-infrared, and the millimeter wavelength regions as well as a number of meteorological parameters have been measured at the Ypenburg Airfield near the Hague, The Netherlands. These transmittances are presented by means of monthly histograms showing frequency and cumulative distributions of surveys over three years. Scatter-plots are used to explain the interrelationships of the transmittances. Also the relations between transmittances and rain rate, density of fog, relative and absolute humidity are shown graphically. PMID:20396008

Janssen, L H; van Schie, J

1982-06-15

70

Array analysis of electromagnetic radiation from radio transmitters for submarine communication  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

71

A radio frequency coaxial feedthrough  

DOEpatents

An improved radio frequency coaxial transmission line vacuum feedthrough is 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 reflection 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 the voltage and power handling capabilities of a feedthrough.

Owens, T.L.

1987-12-07

72

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

USGS Publications Warehouse

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.

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

1988-01-01

73

Integrally formed radio frequency quadrupole  

DOEpatents

An improved radio frequency quadrupole (10) is provided having an elongate housing (11) with an elongate central axis (12) and top, bottom and two side walls (13a-d) symmetrically disposed about the axis, and vanes (14a-d) formed integrally with the walls (13a-d), the vanes (14a-d) each having a cross-section at right angles to the central axis (12) which tapers inwardly toward the axis to form electrode tips (15a-d) spaced from each other by predetermined distances. Each of the four walls (13a-d), and the vanes (14a-d) integral therewith, is a separate structural element having a central lengthwise plane (16) passing through the tip of the vane, the walls (13a-d) having flat mounting surfaces (17, 18) at right angles to and parallel to the control plane (16), respectively, which are butted together to position the walls and vane tips relative to each other.

Abbott, Steven R. (Concord, CA)

1989-01-01

74

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

E-print Network

in the design of this system, since the FCC has tight restrictions regarding the stability of transmitters in the VHF and UHF frequency ranges. This system operates in the 450-470 MHz frequency range and is fi equency stabilized via a crystal with frequency... . . Oscillator Frequency Stability Test Setup. . Typical User Interface to Automated Test Software ?, Automated Signal Analysis Via HP-IB Instrumentation ??, Oscillator Frequency Shift Caused By Antenna Loading . . . . Oscillator Measurement Using Test...

Klughart, Kevin Mark

1992-01-01

75

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2011 CFR

... External radio frequency power amplifiers. 2.815 Section 2.815 ...External radio frequency power amplifiers. (a) As used in this part, an external radio frequency power amplifier is any device which,...

2011-10-01

76

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2012 CFR

... External radio frequency power amplifiers. 2.815 Section 2.815 ...External radio frequency power amplifiers. (a) As used in this part, an external radio frequency power amplifier is any device which,...

2012-10-01

77

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2013 CFR

... External radio frequency power amplifiers. 2.815 Section 2.815 ...External radio frequency power amplifiers. (a) As used in this part, an external radio frequency power amplifier is any device which,...

2013-10-01

78

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2014 CFR

... External radio frequency power amplifiers. 2.815 Section 2.815 ...External radio frequency power amplifiers. (a) As used in this part, an external radio frequency power amplifier is any device which,...

2014-10-01

79

47 CFR 2.815 - External radio frequency power amplifiers.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false External radio frequency power amplifiers. 2.815...COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.815...

2010-10-01

80

Wideband digital low-frequency radio receiver  

NASA Astrophysics Data System (ADS)

A wideband digital low-frequency radio receiver for scientific applications is described. The portable battery-powered instrument has the capability to record electric field strengths in the frequency range from ~4 Hz to ~400 kHz with a sampling frequency of 1 MHz, an amplitude resolution of ~35 µV and a timing accuracy of ~12 ns whilst performing continuous digital waveform recordings for several days. The instrument strictly follows a modular design such that it can be extended to higher frequencies and timing accuracy when the corresponding digital technology becomes available. The low-cost radio receiver can be developed into an interferometric network by synchronizing individual radio receivers to map the low-frequency radio sky. The first measurements of atmospheric electric fields are carried out at Exmoor National Park in Southwest England to illustrate the capabilities of the novel instrument.

Füllekrug, M.

2010-01-01

81

Multi-mode radio frequency device  

DOEpatents

A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

Gilbert, Ronald W. (Morgan Hill, CA); Carrender, Curtis Lee (Morgan Hill, CA); Anderson, Gordon A. (Benton City, WA); Steele, Kerry D. (Kennewick, WA)

2007-02-13

82

High power radio frequency attenuation device  

DOEpatents

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.

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

1984-01-01

83

Radiophysical and radio astronomical diagnostics of ionospheric effects induced by a ground-based infrasonic transmitter (preliminary results)  

Microsoft Academic Search

We present results of preliminary studies aimed at detection of weak ionospheric disturbances induced by acoustic emission\\u000a of a ground-based controlled transmitter. Radio astronomical and radiophysical facilities based on the decameter radio telescope\\u000a URAN-3 were used in these experiments. Three methods were applied in this study: occultation of the disturbed region by radio\\u000a emission from discrete cosmic sources, scattering of

V. V. Koshovy

1999-01-01

84

Long-term health effects of harness-mounted radio transmitters in red kites (Milvus milvus) in England.  

PubMed

In 1989, the Nature Conservancy Council and the Royal Society for the Protection of Birds commenced reintroduction of the red kite (Milvus milvus) according to International Union for Conservation of Nature criteria. Following 22 years of intensive effort, the red kite reintroduction programme has been a success with an estimated 1000 pairs now breeding in England. Post-release health surveillance is ongoing and has been achieved through radio-tracking, monitoring breeding at nest sites and pathological examinations of any red kites found dead. Tail-mounted radio transmitters were fitted from 1989 with harness-mounted radio transmitters being preferentially used since 2000. Since 2000, 180 individuals have been recovered for postmortem examination. Eighteen of these birds had previously had a harness-mounted radio transmitter fitted and four of these (22 per cent) had moderate to severe lesions associated with the presence of the harness and radio transmitter including chronic necrogranulomatous inflammation, deep muscular exposure and distorted muscular conformation. Failure to breed was also reported in two of these individuals over the preceding year(s), although it is not known whether the presence of the harness contributed to this failure. Duration of deployment may have been a significant factor in the formation of these lesions as those with lesions (n=4) had a statistically significant (P=0.009) longer duration of deployment compared to those without lesions (n=14). No lesions were reported in those red kites fitted with tail-transmitters. PMID:21846683

Peniche, G; Vaughan-Higgins, R; Carter, I; Pocknell, A; Simpson, D; Sainsbury, A

2011-09-17

85

47 CFR 95.621 - GMRS transmitter channel frequencies.  

Code of Federal Regulations, 2010 CFR

...carrier frequency, suppressed or otherwise, may not deviate by more than the specified frequency tolerance) are 462.5500, 462.5625, 462.5750, 462.5875, 462.6000, 462.6125, 462.6250, 462.6375, 462.6500, 462.6625, 462.6750,...

2010-10-01

86

47 CFR 95.621 - GMRS transmitter channel frequencies.  

Code of Federal Regulations, 2012 CFR

...carrier frequency, suppressed or otherwise, may not deviate by more than the specified frequency tolerance) are 462.5500, 462.5625, 462.5750, 462.5875, 462.6000, 462.6125, 462.6250, 462.6375, 462.6500, 462.6625, 462.6750,...

2012-10-01

87

47 CFR 95.621 - GMRS transmitter channel frequencies.  

Code of Federal Regulations, 2011 CFR

...carrier frequency, suppressed or otherwise, may not deviate by more than the specified frequency tolerance) are 462.5500, 462.5625, 462.5750, 462.5875, 462.6000, 462.6125, 462.6250, 462.6375, 462.6500, 462.6625, 462.6750,...

2011-10-01

88

47 CFR 95.621 - GMRS transmitter channel frequencies.  

Code of Federal Regulations, 2013 CFR

...carrier frequency, suppressed or otherwise, may not deviate by more than the specified frequency tolerance) are 462.5500, 462.5625, 462.5750, 462.5875, 462.6000, 462.6125, 462.6250, 462.6375, 462.6500, 462.6625, 462.6750,...

2013-10-01

89

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

90

LOFAR, a new low frequency radio telescope  

Microsoft Academic Search

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

Huub Röttgering

2003-01-01

91

Radio Frequency Identification iny integrated circuits equipped with radio an-  

E-print Network

Benetton's plans "to weave radio frequency ID chips into its garments to track its clothes worldwide."1 their knowledge orconsent.TypicalofthiscoverageisaWiredNewsarticle that erroneously reported clothing giant For RFID manufacturers, these tiny chips are the 21st CenturyreplacementfortheUniversalProductCodebar codes

Han, Richard Y.

92

Acquisition signal transmitter  

NASA Technical Reports Server (NTRS)

An encoded information transmitter which transmits a radio frequency carrier that is amplitude modulated by a constant frequency waveform and thereafter amplitude modulated by a predetermined encoded waveform, the constant frequency waveform modulated carrier constituting an acquisition signal and the encoded waveform modulated carrier constituting an information bearing signal, the acquisition signal providing enhanced signal acquisition and interference rejection favoring the information bearing signal. One specific application for this transmitter is as a distress transmitter where a conventional, legislated audio tone modulated signal is transmitted followed first by the acquisition signal and then the information bearing signal, the information bearing signal being encoded with, among other things, vehicle identification data. The acquistion signal enables a receiver to acquire the information bearing signal where the received signal is low and/or where the received signal has a low signal-to-noise ratio in an environment where there are multiple signals in the same frequency band as the information bearing signal.

Friedman, Morton L. (Inventor)

1989-01-01

93

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

USGS Publications Warehouse

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.

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

2007-01-01

94

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

PubMed

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

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

2007-03-01

95

Low-frequency radio emissions at Neptune  

NASA Technical Reports Server (NTRS)

The Voyager 2 plasma wave receiver detected weak radio emissions from Neptune's magnetosphere in the frequency range of 3 - 60 kHz. The emissions occurred in bursts lasting for typically 1.5 hours, often occurring twice per planetary rotation. Most of these radio bursts were detected within several degrees of the magnetic equatorial plane. During the passage through the magnetosphere, electrostatic upper hybrid resonance bands were observed close to the magnetic equator in conjunction with intensifications of the radio emissions at frequencies close to and above the upper hybrid bands. Further, near closest approach, the radio emissions were observed to cross the right-hand cutoff frequency with no apparent attenuation. It is concluded that the Neptunian radio emissions below about 60 kHz are produced by mode conversion from the upper hybrid waves and propagate in the ordinary mode into beams within about 12 deg of the magnetic equator. There is also evidence of an extraordinary mode emission at about 60 kHz which is apparently generated by an entirely different source from the escaping continuum radiation.

Kurth, W. S.; Gurnett, D. A.; Cairns, I. H.; Barbosa, D. D.; Poynter, R. L.

1990-01-01

96

Terahertz Optical Subcarrier Radio Frequency Generation  

NASA Astrophysics Data System (ADS)

There is interest to develop optically generated radio frequency signals for systems such as radar, microwave-over-fiber, and high-frequency wireless communication. Because such systems have the potential for multi-channel broadband communication. We demonstrate the generation of terahertz optical subcarrier radio frequencies in a semiconductor optical amplifier. The circuit arrangement consists of a 1550 nm pigtailed laser diode driven below its lasing threshold to generate a spectrum of spontaneous emission. The spontaneous emissions signalsare passed through a semiconductor amplifier driveninto saturation. A fraction of the output signal emerging from theamplifier is fed back into the input of the amplifier. By appropriately arranging the phases of the input and the feedback signals, optical subcarrier frequencies of up to 3.75 terahertzwere generated and measured.

Sanchez, Sonia; Donkor, Eric

2000-11-01

97

Cost cutting using radio frequency inventory control.  

PubMed

Bar coding should be a staple in every hospital by now--but it's not. The author tells how bar coding and the use of radio frequency transmission of inventory data direct to their mainframe computer has saved them time and money. PMID:10117777

Weber, J

1992-05-01

98

Low Frequency Radio Astronomy with the existing and future radio telescopes  

E-print Network

Low Frequency Radio Astronomy with the existing and future radio telescopes A.A. Konovalenko radio telescope and also the creation of new large telescope of 10 ­ 70 MHz frequency range, Emmen, "Astrophisycs in the LOFAR era") #12;#12;#12;The low-frequency radio telescopes in Europe LOFAR

Demoulin, Pascal

99

Characterization of optical microring ultrasound detector by using a high frequency focused photoacoustic transmitter  

PubMed Central

We characterize a response of optical microring resonator to high frequency focused ultrasound. To properly evaluate the response over high frequency and broadband spectrum, we use a photoacoustic concave transmitter generating and subsequently focusing the ultrasound. A detected focused profile reveals two types of spatial peaks due to the special ring-shaped detector geometry interacting with the high frequency focused ultrasound. Spectral analysis shows that those peaks are contributed by the main and the side lobes of focused ultrasound, respectively. Experimental focal widths agree with theoretical values within ±2 ?m error, which can be attributed to the narrow width of waveguide. PMID:19902003

Won Baac, Hyoung; Ling, Tao; Huang, Sheng-Wen; Ashkenazi, Shai; Guo, L. Jay

2009-01-01

100

Characterization of optical microring ultrasound detector by using a high frequency focused photoacoustic transmitter.  

PubMed

We characterize a response of optical microring resonator to high frequency focused ultrasound. To properly evaluate the response over high frequency and broadband spectrum, we use a photoacoustic concave transmitter generating and subsequently focusing the ultrasound. A detected focused profile reveals two types of spatial peaks due to the special ring-shaped detector geometry interacting with the high frequency focused ultrasound. Spectral analysis shows that those peaks are contributed by the main and the side lobes of focused ultrasound, respectively. Experimental focal widths agree with theoretical values within +/-2 mum error, which can be attributed to the narrow width of waveguide. PMID:19902003

Won Baac, Hyoung; Ling, Tao; Huang, Sheng-Wen; Ashkenazi, Shai; Guo, L Jay

2009-10-01

101

Digital avionics susceptibility to high energy radio frequency fields  

NASA Astrophysics Data System (ADS)

Generally, noncritical avionic systems for transport category aircraft have been designed to meet radio frequency (RF) susceptibility requirements set forth in RTCA DO 160B, environmental conditions and test procedures for airborne equipment. Section 20 of this document controls the electromagnetic interference (EMI) hardening for avionics equipment to levels of 1 and 2 V/m. Currently, US equipment manufacturers are designing flight-critical fly-by-wire avionics to a much higher level. The US Federal Aviation Administration (FAA) has requested that the RTCA SC-135 high-energy radio frequency (HERF) working group develop appropriate testing procedures for section 20 of RTCA DO 160B for radiated and conducted susceptibility at the box and systems level. The FAA has also requested the SAE AE4R committee to address installed systems testing, airframe shielding effects and RF environment monitoring. Emitters of interest include radar (ground, ship, and aircraft) commercial broadcast and TV station, mobile communication, and other transmitters that could possibly affect commercial aircraft.

Larsen, William E.

102

On the use of Very Low Frequency transmitter data for remote sensing of atmospheric gravity and planetary waves  

NASA Astrophysics Data System (ADS)

Continuous ground-based monitoring of Very Low Frequency (VLF) transmitter signals is an efficient remote sensing tool for studying of the lower ionosphere (60-90 km). Here, we present the use of VLF radio data to study short-period (?min-hrs) atmospheric gravity waves and long-period (?days) planetary waves. We analyse VLF data from several receiving stations obtained by ICSP-VLF network during the total solar eclipse of July, 2009 to show the existence of short-period atmospheric gravity waves. We find dominant wave periods range from 10 min to 1 h around the time of maximum eclipse phase which could be associated with atmospheric gravity waves excited due to the eclipse. We also analyse VLF amplitude data of 2007 received at ICSP, Kolkata from VTX (18.2 kHz) transmitter for planetary wave-type oscillations in the mesosphere-lower ionosphere system. Fourier and wavelet analysis show presence of periodic structures with periodicity in the range of 5-27 days. We compare VLF planetary spectrum with spectrum obtained from total column density of Ozone and mesospheric average temperature data which may indicate vertical coupling between the stratosphere and ionosphere in winter to early spring time.

Pal, Sujay; Chakraborty, Suman; Chakrabarti, Sandip K.

2015-02-01

103

Sprites in low-frequency radio noise  

NASA Astrophysics Data System (ADS)

Low-frequency radio noise is the electromagnetic background radiation which is compared here to the luminosity of 39 sprites recorded with a low-light video camera. It is found that the sprite luminosities coincide with ˜10-30 ms long sudden enhancements of the electromagnetic background radiation ˜6-8 ?V m-1Hz-1/2(˜6-9 dB) with a relative maximum near ˜125 kHz as measured with a wideband (˜1-400 kHz) digital radio receiver. The sprites cluster in 10 groups of 2-5 consecutive sprites which are paralleled by up to ˜1 s long slowly varying enhancements of the electromagnetic background radiation ˜4-5 ?V m-1Hz-1/2(˜2-4 dB). The observed electric field strengths place an upper bound on the low-frequency radiation from the electron multiplication associated with the exponential growth and branching sprite streamers predicted by Qin et al. [2012a]. This upper bound corresponds to a maximum of ˜300-5000 sprite streamers at ˜40 km height above thunderclouds. Some part of the observed electromagnetic background radiation might result from the superposition of low-frequency radiation emanating from the quick succession of numerous horizontal lightning strokes and/or stepped leaders inside thunderclouds which would constitute a fundamentally novel quasi-static discharge process inside thunderclouds radiating slowly varying low frequency radio noise.

Füllekrug, Martin; Mezentsev, Andrew; Soula, Serge; Velde, Oscar; Farges, Thomas

2013-05-01

104

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2013-03-01

105

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

NASA Astrophysics Data System (ADS)

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.

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

106

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

107

Low Frequency Radio Signals from Sprite Streamers  

NASA Astrophysics Data System (ADS)

Sprites are mesospheric discharges that carry significant electrical currents and produce radio signals observed typically in the extremely low (ELF) to very low (VLF) frequency bands [Cummer et al., GRL, 25, 1281, 1998]. Recently, Low-Frequency (LF) radio observations of sprite-producing lightning discharges have shown the existence of consecutive broadband pulses exhibiting EM radiation that spans in the LF range, and it has been suggested that this LF radio signals may stem from non-luminous relativistic electron beams above thunderstorms [Fullekrug et al., JGR, 115, A00E09, 2010]. In this talk, we present the first theoretical estimates of the radio signals produced by individual sprite streamers using simulation results from a plasma fluid model. It is demonstrated that the spectral content of the radiation produced by sprite streamers is a function of the air density N and the lightning-induced quasi-static ambient electric field E in the regions of space where the sprite streamers are propagating. We demonstrate that the exponential growth of the current in sprite streamers at 75 km would be preferentially associated with electromagnetic radiation in the frequency range from 0 and up to ˜3 kHz, whereas the growth of the streamer current at 40 km could produce radiation with frequencies up to ˜300 kHz, consistently with the scaling of atmospheric air density [Kosar et al., JGR, 117, A08328, 2012]. We further conjecture that the periodic branching of streamers may lead to a radiation spectrum enhancement in the VLF to LF range. The present study shows that sprite streamers could be responsible for at least part of the LF radiation associated with sprite-producing lightning discharges that was detected recently by Fullekrug et al. [2010].

Qin, J.; Celestin, S. J.; Pasko, V. P.

2013-12-01

108

An Introduction to Radio Frequency Engineering  

NASA Astrophysics Data System (ADS)

Using an easily understood approach combined with numerous worked examples, illustrations and homework problems, this textbook focuses on minimizing the mathematics needed to grasp radio frequency engineering. The book includes broad coverage of RF systems, circuit design, antennas, propagation and digital techniques. Written for upper level undergraduate courses, it will also provide an excellent introduction to the subject for graduate students, researchers and practicing engineers.

Coleman, Christopher

2004-06-01

109

Review of radio frequency microelectromechanical systems technology  

Microsoft Academic Search

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

S. Lucyszyn

2004-01-01

110

Effects of external and surgically implanted dummy radio transmitters on mortality, swimming performance and physiological status of juvenile masu salmon Oncorhynchus masou.  

PubMed

The effects of external and surgically implanted radio transmitters on juvenile masu salmon Oncorhynchus masou were examined. External attachment of transmitters significantly decreased the survival of fish and caused a decreased critical swimming speed compared with surgical implantation. Although plasma cortisol, plasma glucose and haematocrit values did not differ significantly among groups, it appeared that the most suitable transmitter attachment method for juvenile O. masou may be surgical implantation. PMID:20735543

Makiguchi, Y; Ueda, H

2009-01-01

111

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

USGS Publications Warehouse

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.

Mulcahy, D.M.; Esler, D.

1999-01-01

112

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

PubMed

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

Mulcahy, D M; Esler, D

1999-09-01

113

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...COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES...Passenger Boats § 80.927 Antenna radio frequency indicator. The...

2010-10-01

114

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...COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES...Bridge-to-Bridge Act § 80.1019 Antenna radio frequency indicator. Each...

2010-10-01

115

The Mariner Mars 1971 radio frequency subsystem  

NASA Technical Reports Server (NTRS)

The radio frequency subsystem (RFS) for the Mariner Mars 1971 (MM'71) spacecraft is described. The MM'69 RFS was used as the baseline design for the MM'71 RFS, and the report describes the design changes made to the 1969 RFS for use on MM'71. It also cites various problems encountered during the fabrication and testing of the RFS, as well as the types of tests to which the RFS was subjected. In areas where significant problems were encountered, a detailed description of the problem and its solution is presented. In addition, some recommendations are given for modifications to the RFS and test techniques for future programs.

Hughes, R. S.

1972-01-01

116

Radio frequency identification applications in hospital environments.  

PubMed

Radio frequency identification (RFID) technology has recently begun to receive increased interest from practitioners and academicians. This interest is driven by mandates from major retailers such as Wal-Mart, Target and Metro Group, and the United States Department of Defense, in order to increase the efficiency and visibility of material and information flows in the supply chain. However, supply chain managers do not have a monopoly on the deployment of RFID. In this article, the authors discuss the potential benefits, the areas of applications, the implementation challenges, and the corresponding strategies of RFID in hospital environments. PMID:16913301

Wicks, Angela M; Visich, John K; Li, Suhong

2006-01-01

117

Reception conditions of low frequency (LF) transmitter signals onboard DEMETER micro-satellite  

NASA Astrophysics Data System (ADS)

We analyze the flux density variation associated to low frequency (LF) broadcasting transmitters observed by the ICE electric field experiment onboard DEMETER micro-satellite. We select five stations localised around the Mediterranean and the black seas: Tipaza (252 kHz, 02°28'E, 36°33'N, Algeria), Roumoules (216 kHz, 06°08'E, 43°47'N, Monte Carlo), Polatli (180 kHz, 32°25'E, 39°45'N, Turkey), Nador (171 kHz, 02°55'W, 35°02'N, Morocco) and Brasov (153 kHz, 25°36'E,45°40', Romania). The detection of the LF transmitter signals by DEMETER micro-satellite is found to depend on the radiated power, the emitted frequency, and the orbit paths with regard to the location of the stations. This leads us to characterise the reception condition of the LF signals and to define time intervals where the detection probability is high. We firstly discuss the dependence of the reception conditions on the ionospheric disturbances due to the geomagnetic and solar activities, and we secondly attempt to estimate the global electric environment above the Mediterranean and the black seas.

Boudjada, Mohammed Y.; Biagi, Pier F.; Sawas, Sami; Galopeau, Patrick H. M.; Besser, Bruno; Wolbang, Daniel; Prattes, Gustav; Eichelberger, Hans; Stangl, Günter; Parrot, Michel; Schwingenschuh, Konrad

2014-05-01

118

Point-to-point measurement of radio frequency attenuation in South Polar ice  

NASA Astrophysics Data System (ADS)

For ultra high energy (UHE) electromagnetic showers in a dense medium, radio frequency Cherenkov emission is enhanced due to the Askaryan effect. Present and future detectors such as RICE, ANITA, ARIANNA and the Askaryan Radio Array (ARA) exploit this effect to detect UHE neutrinos interacting with Antarctic ice. The radio frequency electromagnetic wave attenuation length (the distance over which signal amplitude diminishes by a factor of 1/e due to absorption or scattering) is of tantamount importance as it determines the size scale and effective volume of these detectors. Previous attenuation measurements rely on reflections off the bedrock of signals from a surface-mounted transmitter. Using RICE in-ice transmitters and IceCube Radio Extension in-ice receivers, we are conducting a point-to-point attenuation measurement in the upper 1500 meters of South Polar ice, the region of interest for planned near-surface detectors such as ARA. We will present the analysis method as well as preliminary results.

Richman, Michael; Hoffman, Kara

2011-04-01

119

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

E-print Network

RADIO-CONTROLLED CYBORG BEETLES: A RADIO-FREQUENCY SYSTEM FOR INSECT NEURAL FLIGHT CONTROL H. Sato1 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

Maharbiz, Michel

120

Two Phase Spectrum Sharing for Frequency-Agile Radio Networks  

E-print Network

1 Two Phase Spectrum Sharing for Frequency-Agile Radio Networks Zhenhua Feng and Yaling Yang, Blacksburg, Virginia 24060 Email: {zhenhua, yyang8}@vt.edu Abstract--Modern frequency-agile radios utilization. In this paper, we present a theoretical framework that capitalize on the frequency agility

Ha, Dong S.

121

Assessment of Barotrauma Resulting from Rapid Decompression of Depth Acclimated Juvenile Chinook Salmon Bearing Radio Telemetry Transmitters  

SciTech Connect

A multifactor study was conducted by Battelle for the US Army Corps of Engineers to assess the significance of the presence of a radio telemetry transmitter on the effects of rapid decompression from simulated hydro turbine passage on depth acclimated juvenile run-of-the-river Chinook salmon. Study factors were: (1) juvenile chinook salmon age;, subyearling or yearling, (2) radio transmitter present or absent, (3) three transmitter implantation factors: gastric, surgical, and no transmitter, and (4) four acclimation depth factors: 1, 10, 20, and 40 foot submergence equivalent absolute pressure, for a total of 48 unique treatments. Exposed fish were examined for changes in behavior, presence or absence of barotrauma injuries, and immediate or delayed mortality. Logistic models were used to test hypotheses that addressed study objectives. The presence of a radio transmitter was found to significantly increase the risk of barotrauma injury and mortality at exposure to rapid decompression. Gastric implantation was found to present a higher risk than surgical implantation. Fish were exposed within 48 hours of transmitter implantation so surgical incisions were not completely healed. The difference in results obtained for gastric and surgical implantation methods may be the result of study design and the results may have been different if tested fish had completely healed surgical wounds. However, the test did simulate the typical surgical-release time frame for in-river telemetry studies of fish survival so the results are probably representative for fish passing through a turbine shortly following release into the river. The finding of a significant difference in response to rapid decompression between fish bearing radio transmitters and those not implies a bias may exist in estimates of turbine passage survival obtained using radio telemetry. However, the rapid decompression (simulated turbine passage) conditions used for the study represented near worst case exposure for fish passing through turbines. At this time, insufficient data exist about the distribution of river-run fish entering turbines, and particularly, the distribution of fish passing through turbine runners, to extrapolate study findings to the population of fish passing through FCRPS turbines. This study is the first study examining rapid decompression study to include acclimation depth as an experimental factor for physostomous fish. We found that fish acclimated to deeper depth were significantly more vulnerable to barotrauma injury and death. Insufficient information about the distribution of fish entering turbines and their depth acclimation currently exists to extrapolate these findings to the population of fish passing through turbines. However, the risk of barotrauma for turbine-passed fish could be particularly high for subyearling Chinook salmon that migrate downstream at deeper depths late in the early summer portion of the outmigration. Barotrauma injuries led to immediate mortality delayed mortality and potential mortality due to increased susceptibility to predation resulting from loss of equilibrium or swim bladder rupture.

Brown, Richard S.; Carlson, Thomas J.; Welch, Abigail E.; Stephenson, John R.; Abernethy, Cary S.; McKinstry, Craig A.; Theriault, Marie-Helene

2007-09-06

122

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

PubMed

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 10(18) m(-3) is produced in argon plasma. Although lower densities are obtained in hydrogen plasma, it drastically increased up to 5x10(18) m(-3) with an axial magnetic field of around 100 G applied in the driver region. Effects of the magnetic field and gas pressure are investigated in the RF produced plasma with the frequency of several hundred kilohertz. PMID:20192414

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

2010-02-01

123

Radio frequency ion source operated with field effect transistor based radio frequency systema)  

NASA Astrophysics Data System (ADS)

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 of around 100 G applied in the driver region. Effects of the magnetic field and gas pressure are investigated in the RF produced plasma with the frequency of several hundred kilohertz.

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

2010-02-01

124

Radio-frequency low-coherence interferometry.  

PubMed

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

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

2014-06-15

125

An improved integrally formed radio frequency quadrupole  

DOEpatents

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.

Abbott, S.R.

1987-10-05

126

Radio-frequency quadrupole linear accelerator  

SciTech Connect

The radio-frequency quadrupole (RFQ) is a new linear accelerator concept in which rf electric fields are used to focus, bunch, and accelerate the beam. Because the RFQ can provide strong focusing at low velocities, it can capture a high-current dc ion beam from a low-voltage source and accelerate it to an energy of 1 MeV/nucleon within a distance of a few meters. A recent experimental test at the Los Alamos Scientific Laboratory (LASL) has confirmed the expected performance of this structure and has stimulated interest in a wide variety of applications. The general properties of the RFQ are reviewed and examples of applications of this new accelerator are presented.

Wangler, T.P.; Stokes, R.H.

1980-01-01

127

Requirements for radio frequency identification in healthcare.  

PubMed

Radio frequency identification (RFID) is a growing technology among different industries. As a technology, it has been used since the Second World War, but just in the last decade, the information technology (IT) community and healthcare have been taking more action on studying and developing the technology. In this paper, we represent the general requirements that healthcare sets for the RFID technology. The paper is a part of the research project MaISSI (Managing IT Services and Service Implementation) where our aim is to implement an automated identification system (AIMC) for our case hospital's medication care. The AIMC uses the RFID technology for patient identification and the bar code technology for medication identification. The system will automate the identification processes during medication administration, reduce medication errors and increase the patient safety. PMID:19745405

Lahtela, Antti; Hassinen, Marko

2009-01-01

128

Hybrid optical radio frequency airborne communications  

NASA Astrophysics Data System (ADS)

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.

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

129

Interstellar Radio Communication and the Frequency Selection Problem  

Microsoft Academic Search

THE largest microwave radio telescope on Earth, at the Arecibo Observatory of the National Astronomy and Ionosphere Center, will soon have the capability of communicating with an identical radio telescope, if such exists, anywhere in the Galaxy. But such communication assumes some previous agreement between the transmitting and receiving civilizations, or mutual discovery of the chosen radio frequency, bandpass, information

F. D. Drake; Carl Sagan

1973-01-01

130

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...

131

Phase manipulation for efficient radio frequency transmission  

E-print Network

Power amplifiers (PAs) for microwave communications are generally the most power-hungry element of a transmitter. High linearity is required for modern digital communications standards, and often is achieved at the expense ...

Barton, Taylor Wallis

2012-01-01

132

An overview of DREV's activities on pulsed CO2 laser transmitters: Frequency stability and lifetime aspects  

NASA Technical Reports Server (NTRS)

After introducing the desired features in a transmitter for laser radar applications, the output characteristics of several configurations of frequency-stable TEA-CO2 lasers are reviewed. Based on work carried out at the Defence Research Establishment Valcartier (DREV), output pulses are examined from short cavity lasers, CW-TEA hybrid lasers, and amplifiers for low power pulses. It is concluded that the technique of injecting a low-power laser beam into a TEA laser resonator with Gaussian reflectivity mirrors should be investigated because it appears well adapted to producing high energy, single mode, low chirp pulses. Finally, a brief report on tests carried out on catalysts composed of stannic oxide and noble metals demonstrates the potential of these catalysts, operating at close to room temperature, to provide complete closed-cycle laser operation.

Cruickshank, James; Pace, Paul; Mathieu, Pierre

1987-01-01

133

Radio frequency seismic gathering system employing an airborne blimp  

Microsoft Academic Search

The central station of a radio-connected seismic surveying system uses a tethered blimp carrying an antenna and an electronics package including a dc voltage\\/rf decoupler, a variable dc controlled preamplifier, a p-i-n diode switch for changing the antenna from receive to transmit operation, a transmitter and modulator and a battery. An rf coaxial cable to ground provides means for controlling

R. A. Imm; W. T. McDavid; J. M. Mckeever

1980-01-01

134

Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD)  

E-print Network

Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD) Kurt Alexander Polzin;Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD) Prepared by: Kurt Alexander Polzin Dr. Michael R. LaPointe Dissertation Reader #12;c Copyright by Kurt Alexander Polzin, 2006. All

Choueiri, Edgar

135

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...

136

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, ...

137

Radio Frequency Ablation Registration, Segmentation, and Fusion Tool  

Microsoft Academic Search

The Radio Frequency Ablation Segmentation Tool (RFAST) is a software application developed using NIH's Medical Image Processing Analysis and Visualization (MIPAV) API for the specific purpose of assisting physicians in the planning of radio frequency ablation (RFA) procedures. The RFAST application sequentially leads the physician through the steps necessary to register, fuse, segment, visualize and plan the RFA treatment. Three-dimensional

Evan S. Mccreedy; Ruida Cheng; Paul F. Hemler; Anand Viswanathan; Brad J. Wood; Matthew J. Mcauliffe

2005-01-01

138

Radio Frequency Ablation Registration, Segmentation, and Fusion Tool  

Microsoft Academic Search

Abstract— The Radio Frequency Ablation Segmentation Tool (RFAST) is a software application developed using NIH’s Medical Image Processing Analysis and Visualization (MIPAV) API for the specific purpose of assisting physicians in the planning of radio frequency ablation (RFA) procedures. The RFAST application sequentially leads the physician through the steps necessary to register, fuse, segment, visualize and plan the RFA treatment.

Evan S. Mccreedy; Ruida Cheng; Paul F. Hemler; Anand Viswanathan; Bradford J. Wood; Matthew J. Mcauliffe

2006-01-01

139

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...

140

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

USGS Publications Warehouse

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.

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

2007-01-01

141

Cassini/RPWS: A low frequency radio imager at Saturn  

NASA Astrophysics Data System (ADS)

The High Frequency Receiver (HFR) of the Radio and Plasma Waves Science experiment (RPWS) onboard Cassini is a sensitive, and versatile radio instrument. Although the radio antenna connected to this instrument have no intrinsic directivity, the HFR measurements can provide instantaneous direction of arrival, flux density and polarization degree of the observed radio waves. Hence, the HFR can be described as an full-sky radio imager. As the instrument provides direction of arrival, radio sources can be located with some assumption on the propagation between the source and the observer. Hence, it is possible to produce radio source maps and correlate them with observations at other wavelengths, such as UV or IR observations of the auroral regions of Saturn. The flux and polarization measurements together with the time-frequency shape of the radio emissions can also be used to identify the radio emission processes. We present a review of the results of the Cassini/RPWS/HFR observations since its arrival at Saturn in 2004: interpretation of the radio arc shapes and equatorial shadow zones; in-situ observations in the radio source region; comparison with other wavelengths and particle measurements; confirmation of the Cyclotron Maser Instability (CMI) as the main emission mechanism for auroral radio emissions; monitoring of the radio emission variability in time and location, etc.

Cecconi, Baptiste; Lamy, Laurent; Zarka, Philippe

2014-05-01

142

SOUTHEASTERN NATURALIST2010 9(X):0000 Avian Radio-transmitter Harness Wear and Failure  

E-print Network

methods (polyester thread, cotton thread, and Gorilla Super GlueTM) using dummy transmitters exposed harnesses using Gorilla Super GlueTM resulted in the earliest and most consistent harness failure. Polyester times for both 7-mm- and 9-mm-wide polyester- coated rubber elastic and Gorilla Super GlueTM fastening

Gawlik, Dale E.

143

47 CFR 87.195 - Frequencies.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

144

47 CFR 87.195 - Frequencies.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

145

47 CFR 87.195 - Frequencies.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

146

47 CFR 87.195 - Frequencies.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

147

Low Frequency Study of Rotating Radio Transients  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

148

Method and apparatus for radio frequency ceramic sintering  

DOEpatents

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.

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

1993-01-01

149

Method and apparatus for radio frequency ceramic sintering  

DOEpatents

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.

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

1993-11-30

150

Directional Radio-Frequency Identification Tag Reader  

NASA Technical Reports Server (NTRS)

A directional radio-frequency identification (RFID) tag reader has been designed to facilitate finding a specific object among many objects in a crowded room. The device could be an adjunct to an electronic inventory system that tracks RFID-tagged objects as they move through reader-equipped doorways. Whereas commercial RFID-tag readers do not measure directions to tagged objects, the device is equipped with a phased-array antenna and a received signal-strength indicator (RSSI) circuit for measuring direction. At the beginning of operation, it is set to address only the RFID tag of interest. It then continuously transmits a signal to interrogate that tag while varying the radiation pattern of the antenna. It identifies the direction to the tag as the radiation pattern direction of peak strength of the signal returned by the tag. An approximate distance to the tag is calculated from the peak signal strength. The direction and distance can be displayed on a screen. A prototype containing a Yagi antenna was found to be capable of detecting a 915.5-MHz tag at a distance of approximately equal to 15 ft (approximately equal to 4.6 m).

Medelius, Pedro J.; Taylor, John D.; Henderson, John J.

2004-01-01

151

Extending the ICRF to Higher Radio Frequencies  

NASA Technical Reports Server (NTRS)

The ICRF forms the basis for all astrometry including use as the inertial coordinate system for navigating deep space missions. This frame was defined using S/X-band observations over the past 20+ years. In January 2002, the VLBA approved our proposal for observing time to extend the ICRF to K-band (24 GHz) and Q-band (43 GHz). The first step will be observations at K- and Q-bands on a subset of ICRF sources. Eventually, K- and Q-band multi-epoch observations will be used to estimate positions, flux density and source structure for a large fraction of the current S/X-band ICRF source list. This work will benefit the radio astronomy community by extending the VLBA calibrator list at these bands. In the longer term, we would also like to extend the ICRF to Ka-band (32 GHz). A celestial reference frame will be needed at this frequency to support deep space navigation. A navigation demonstration is being considered for NASA's Mars 2005 mission. The initial K- and Q-band work will serve to identify candidate sources at Ka-band for use with that mission.

Jacobs, C. S.; Jones, D. L.; Lanyi, G. E.; Lowe, S. T.; Naudet, C. J.; Resch, G. M.; Steppe, J. A.; Zhang, L. D.; Ulvestad, J. S.; Taylor, G. B.

2002-01-01

152

The effects of radio frequency radiation on the dc SQUID  

SciTech Connect

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.

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

153

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2012 CFR

...External radio frequency power amplifiers and antenna modifications. 15.204 Section 15...External radio frequency power amplifiers and antenna modifications. (a) Except...radio frequency power amplifier, and an antenna, may be authorized, marketed...

2012-10-01

154

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2011 CFR

...External radio frequency power amplifiers and antenna modifications. 15.204 Section 15...External radio frequency power amplifiers and antenna modifications. (a) Except...radio frequency power amplifier, and an antenna, may be authorized, marketed...

2011-10-01

155

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2010 CFR

...External radio frequency power amplifiers and antenna modifications. 15.204 Section 15...External radio frequency power amplifiers and antenna modifications. (a) Except...radio frequency power amplifier, and an antenna, may be authorized, marketed...

2010-10-01

156

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2013 CFR

...External radio frequency power amplifiers and antenna modifications. 15.204 Section 15...External radio frequency power amplifiers and antenna modifications. (a) Except...radio frequency power amplifier, and an antenna, may be authorized, marketed...

2013-10-01

157

47 CFR 15.204 - External radio frequency power amplifiers and antenna modifications.  

Code of Federal Regulations, 2014 CFR

...External radio frequency power amplifiers and antenna modifications. 15.204 Section 15...External radio frequency power amplifiers and antenna modifications. (a) Except...radio frequency power amplifier, and an antenna, may be authorized, marketed...

2014-10-01

158

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

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

159

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

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

160

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

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

161

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

Code of Federal Regulations, 2014 CFR

...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...

2014-10-01

162

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2013-03-29

163

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

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

164

78 FR 52097 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management  

Federal Register 2010, 2011, 2012, 2013, 2014

...Regulations and Procedures for Federal Radio Frequency Management AGENCY: National...Regulations and Procedures for Federal Radio Frequency Management (NTIA Manual...must comply with when requesting use of radio frequency spectrum. DATES: This...

2013-08-22

165

75 FR 54790 - Revision to the Manual of Regulations and Procedures for Federal Radio Frequency Management  

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2010-09-09

166

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2011-09-15

167

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2012-12-21

168

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

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Marketing of radio frequency devices prior to equipment authorization...COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Marketing of Radio-frequency Devices § 2.803...

2010-10-01

169

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2010-02-11

170

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2011-04-05

171

High-power radio-frequency attenuation device  

DOEpatents

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.

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

1981-12-30

172

The Use of a Solid State Analog Television Transmitter as a Superconducting Electron Gun Power Amplifier  

SciTech Connect

A solid state analog television transmitter designed for 200 MHz operation is being commissioned as a radio frequency power amplifier on the Wisconsin superconducting electron gun cavity. The amplifier consists of three separate radio frequency power combiner cabinets and one monitor and control cabinet. The transmitter employs rugged field effect transistors built into one kilowatt drawers that are individually hot swappable at maximum continuous power output. The total combined power of the transmitter system is 33 kW at 200 MHz, output through a standard coaxial transmission line. A low level radio frequency system is employed to digitally synthesize the 200 MHz signal and precisely control amplitude and phase.

J.G. Kulpin, K.J. Kleman, R.A. Legg

2012-07-01

173

Hybrid Coherent and Frequency-Shifted-Reference Ultrawideband Radio  

E-print Network

Hybrid Coherent and Frequency-Shifted-Reference Ultrawideband Radio Huaping Liu, Member, IEEE fading channels. Index Terms-- Pulsed ultrawideband, frequency-shifted refer- ence, coherent rake, hybrid in the frequency domain. A receiver thus only has to implement a mixer, and not a delay line, and is thus much

Liu, Huaping

174

Radio frequency analog electronics based on carbon nanotube transistors  

E-print Network

Radio frequency analog electronics based on carbon nanotube transistors Coskun Kocabas*, Hoon band with power gains as high as 14 dB. As a demon- stration, we fabricated nanotube transistor radios technologies. The invention of the transistor in 1947 represents the birth of the solid state electronics age

Rogers, John A.

175

Solar observations with a low frequency radio telescope  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

176

An overview of backscattered radio frequency identification system (RFID)  

Microsoft Academic Search

A radio frequency identification (RFID) system is a wireless communication system in which the radio link between the base station and the transponders are furnished by the modulated backscattered waves. The present paper is intended to provide a brief description of various subsystems of the RFID. The various applications of RFID are discussed. Sample results on read\\/write range for a

K. V. S. Rao

1999-01-01

177

DEMONSTRATION BULLETIN: RADIO FREQUENCY HEATING - IIT RESEARCH INSTITUTE  

EPA Science Inventory

Radio frequency heating (RFH) is a process that uses electromagnetic energy generated by radio waves to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. An RFH system developed by the IIT Research Institute ...

178

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

PubMed

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%. PMID:24593446

Peng, Shixiang; Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Zhang, Ailing; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu; Chen, Jia'er

2014-02-01

179

Supplying the power requirements to a sensor network using radio frequency power transfer.  

PubMed

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

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

2012-01-01

180

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

PubMed Central

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

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

2012-01-01

181

Numerical modelling of a radio-frequency micro ion thruster  

E-print Network

A simple performance model is developed for an inductively-coupled radio-frequency micro ion thruster. Methods of particle and energy balance are utilized for modeling the chamber plasma discharge. A transformer model is ...

Tsay, Michael Meng-Tsuan

2006-01-01

182

Radio-frequency spectroscopy of ultracold atomic Fermi gases  

E-print Network

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 ...

Schirotzek, Andre

2010-01-01

183

Radio frequency identification (RFID) applications in semiconductor manufacturing  

E-print Network

Radio frequency identification (RFID) has an enormous potential impact within the semiconductor supply chain, especially within semiconductor manufacturing. The end benefit of RFID will be in the mass serialization, and ...

Cassett, David Ian, 1971-

2004-01-01

184

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

185

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

186

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

187

48 CFR 252.211-7006 - Passive Radio Frequency Identification.  

Code of Federal Regulations, 2014 CFR

...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...

2014-10-01

188

60 FR 3942 - Regulation of Broadcast Radio Frequencies (South Africa)  

Federal Register 2010, 2011, 2012, 2013, 2014

...of Broadcast Radio Frequencies (South Africa) ACTION: Notice--Request for...two-way exchange project to assist South Africa's Independent Broadcasting Authority...Information Service (USIS) posts in South Africa in the development of the...

1995-01-19

189

Radio Frequency & Microwave Energy for the Petro Chemical Industry  

E-print Network

be reviewed to mcet the challenges. OVERVIEW What is electromagnetic energy? Electromagnetic enerb'Y is genemted by taking conventional electricity at a frequcncy of 60 cycles/sec (Hertz) and increasing it to higher Radio Frequency (RF) or Microwave...--- -- ----- ------ ----~ ~ ~ CommunicarioflJ &: Powlr lndusmols RADIO FREQUENCY & MICROWAVE ENERGY FOR THE PETRO CHEMICAL INDUSTRY Rod Raburn - Senior Marketing Communications & Power Industries (Cpr) - Palo Alto California ABSTRACT Electro...

Raburn, R.

190

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

E-print Network

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 ...

Delichatsios, Stefanie Alkistis

2006-01-01

191

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

Code of Federal Regulations, 2010 CFR

...certain aeronautical and marine emergency radio frequencies. 76.616 Section 76...COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE...certain aeronautical and marine emergency radio frequencies. (a) The...

2010-10-01

192

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

193

47 CFR 2.944 - Software defined radios.  

Code of Federal Regulations, 2013 CFR

...the transmitter with operating frequencies, output power, modulation types or other radio frequency parameters outside those...would affect the operating parameters of frequency range, modulation type or maximum output power (either radiated or...

2013-10-01

194

47 CFR 2.944 - Software defined radios.  

Code of Federal Regulations, 2014 CFR

...the transmitter with operating frequencies, output power, modulation types or other radio frequency parameters outside those...would affect the operating parameters of frequency range, modulation type or maximum output power (either radiated or...

2014-10-01

195

Analog optoelectronic independent component analysis for radio frequency signals  

Microsoft Academic Search

This thesis addresses the problem of blind source separation of signals at radio frequencies. Independent component analysis (ICA), which includes a second-order decorrelation followed by a fourth-order decorrelation, uses signal independence to estimate the original signals from the received mixtures. Until now, ICA has been applied to many applications at or below audio frequencies. The work presented here demonstrates that

Martha-Elizabeth Baylor

2007-01-01

196

47 CFR 95.627 - MedRadio transmitters in the 401-406 MHz band.  

Code of Federal Regulations, 2012 CFR

...associated with medical body-worn devices, regardless...a frequency monitoring system as set forth in paragraph...intended to be implanted in a human body, radiated emissions and...a Commission-approved human body simulator and test...

2012-10-01

197

47 CFR 95.627 - MedRadio transmitters in the 401-406 MHz band.  

Code of Federal Regulations, 2013 CFR

...associated with medical body-worn devices, regardless...a frequency monitoring system as set forth in paragraph...intended to be implanted in a human body, radiated emissions and...a Commission-approved human body simulator and test...

2013-10-01

198

Characteristics of Radio-Frequency Circuits Utilizing Ferroelectric Capacitors  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

199

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

PubMed

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

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

2015-02-01

200

Radio frequency interference at Jodrell Bank Observatory within the protected 21 cm band.  

PubMed

Radio frequency interference (RFI) will provide one of the most difficult challenges to systematic Searches for Extraterrestrial Intelligence (SETI) at microwave frequencies. The SETI-specific equipment is being optimized for the detection of signals generated by a technology rather than those generated by natural processes in the universe. If this equipment performs as expected, then it will inevitably detect many signals originating from terrestrial technology. If these terrestrial signals are too numerous and/or strong, the equipment will effectively be blinded to the (presumably) weaker extraterrestrial signals being sought. It is very difficult to assess how much of a problem RFI will actually represent to future observations, without employing the equipment and beginning the search. In 1983 a very high resolution spectrometer was placed at the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England. This equipment permitted an investigation of the interference environment at Jodrell Bank, at that epoch, and at frequencies within the 21 cm band. This band was chosen because it has long been "protected" by international agreement; no transmitters should have been operating at those frequencies. The data collected at Jodrell Bank were expected to serve as a "best case" interference scenario and provide the minimum design requirements for SETI equipment that must function in the real and noisy environment. This paper describes the data collection and analysis along with some preliminary conclusions concerning the nature of the interference environment at Jodrell Bank. PMID:11537747

Tarter, J

1989-01-01

201

Predicting low-frequency radio fluxes of known extrasolar planets  

E-print Network

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).

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

2008-06-02

202

Dual radio frequency plasma source: Understanding via electrical asymmetry effect  

SciTech Connect

On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies ({xi}), ourstudies also predict local maxima for odd integer values of 2{xi} as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources.

Bora, B. [Departamento de Plasma Termonuclear, Comision Chilena de Energia Nuclear (CCHEN), Casilla 188-D, Santiago (Chile); Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Bhuyan, H.; Favre, M.; Wyndham, E. [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Wong, C. S. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2013-04-21

203

Black phosphorus radio-frequency transistors.  

PubMed

Few-layer and thin film forms of layered black phosphorus (BP) have recently emerged as a promising material for applications in high performance nanoelectronics and infrared optoelectronics. Layered BP thin films offer a moderate bandgap of around 0.3 eV and high carrier mobility, which lead to transistors with decent on-off ratios and high on-state current densities. Here, we demonstrate the gigahertz frequency operation of BP field-effect transistors for the first time. The BP transistors demonstrated here show respectable current saturation with an on-off ratio that exceeds 2 × 10(3). We achieved a current density in excess of 270 mA/mm and DC transconductance above 180 mS/mm for hole conduction. Using standard high frequency characterization techniques, we measured a short-circuit current-gain cutoff frequency fT of 12 GHz and a maximum oscillation frequency fmax of 20 GHz in 300 nm channel length devices. BP devices may offer advantages over graphene transistors for high frequency electronics in terms of voltage and power gain due to the good current saturation properties arising from their finite bandgap, thus can be considered as a promising candidate for the future high performance thin film electronics technology for operation in the multi-GHz frequency range and beyond. PMID:25347787

Wang, Han; Wang, Xiaomu; Xia, Fengnian; Wang, Luhao; Jiang, Hao; Xia, Qiangfei; Chin, Matthew L; Dubey, Madan; Han, Shu-jen

2014-11-12

204

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

E-print Network

Air Band Scanner with Retransmission over Local FM Radio Frequencies Using a Software Defined Radio and demodulation functions that are typically implemented in the hardware portion of a radio. #12;Midterm Report it uses [4]. Despite the frequencies only being slightly higher than the FM radio frequency range, air

Yu, Chansu

205

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

NASA Technical Reports Server (NTRS)

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

Simons, Rainee N.; Wintucky, Edwin G.

2014-01-01

206

Detecting Rot in Power Poles with Radio Frequency Scanning  

NASA Astrophysics Data System (ADS)

The potential for detecting rot in power poles with a radio frequency method was tested. Five pentachlorophenol-treated pole sections containing both sound and decayed wood were obtained from out-of-service power poles. Sections were conditioned in 12-percent equilibrium moisture content (EMC) conditions for 12 months prior to testing. Pole sections were scanned over their length by a laboratory prototype that applied 250, 500 and 2000 kHz radio frequency signals to opposed 1-inch diameter metal electrodes in contact with the pole surface. Each capacitor pair scanned each pole cross sectionally at multiple positions along pole longitudinal axis. Signal voltage attenuation and phase shift values for sound and decayed wood sections were recorded. Radio frequency signals for sound wood were compared to those of decayed wood. Radio frequency signals of 2000 kHz yielded the greatest difference in attenuation and phase shift response between sound and decayed wood. For even the best-performing 2000 kHz signal, evaluation of attenuation appeared to be an impractical means to differentiate sound from decayed wood. However, phase shift performed consistently in differentiating sound from decayed wood and, for signal frequencies of 2000 kHz and above, appears to have considerable potential for this purpose.

Steele, P. H.; Cooper, J. E.

2004-02-01

207

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

Microsoft Academic Search

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

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

2009-01-01

208

Four-Sector Cylindrical Radio-Frequency Ion Trap  

NASA Technical Reports Server (NTRS)

Proposed linear radio-frequency ion trap consists of closed metal cylinder partitioned into four equal cylindrical-sector electrodes and two circular end electrodes. Features include relatively large ion-storage capacity and shielding against external fields. Used in frequency-standard laboratories to confine 199Hg+ ions electrodynamically in isolation from external environment. Similar to device described in "Linear Ion Trap for Atomic Clock" (NPO-17758).

Melbourne, Ruthann K.; Prestage, John D.; Maleki, Lutfollah

1992-01-01

209

Carbon Nanotube Radio-Frequency Single-Electron Transistor  

Microsoft Academic Search

We discuss the theory of the radio-frequency single-electron transistor and the measurements that use multiwalled carbon nanotubes as active elements. Our devices made of plasma-enhanced chemical-vapor-deposition nanotubes yield charge sensitivities of 10-20 ?e\\/\\u000a

Leif Roschier; Mika Sillanpää; Wang Taihong; Markus Ahlskog; Sumio Iijima; Pertti Hakonen

2004-01-01

210

Fabrication of the APS Storage Ring radio frequency accelerating cavities  

SciTech Connect

Specification, heat treatment, strength, and fatigue life of the Advanced Photon Source (APS) Storage Ring 352-MHz radio frequency (RF) accelerating cavity copper is discussed. Heat transfer studies, including finite element analysis, and configuration of water cooling is described. Requirements for and techniques of machining are considered. Braze and electron beam joint designs are compared. Vacuum considerations during fabrication are discussed.

Primdahl, K.; Bridges, J.; DePaola, F.; Kustom, R. [Argonne National Lab., IL (US); Snee, D. [Fermi National Accelerator Lab., Batavia, IL (US)

1993-07-01

211

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

Microsoft Academic Search

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

Shawn M

2012-01-01

212

K-BAND RADIO FREQUENCY INTERFERENCE SURVEY OF SOUTHEASTERN MICHIGAN  

E-print Network

K-BAND RADIO FREQUENCY INTERFERENCE SURVEY OF SOUTHEASTERN MICHIGAN Shannon Curry1 , Michael Ahlers University of Michigan 2455 Hayward St. Ann Arbor, MI 48109-2143 USA cruf@umich.edu 2 DTU Space Technical resolution. A K-Band airborne version has been built and flown across southeast Michigan. A kurtosis detector

Ruf, Christopher

213

A Hybrid Radio Frequency and Broadcast Visible Light Communication System  

E-print Network

, limited available spectrum and limited ability to scale with increasing demand. Directional communications Workshop on Optical Wireless Communications, December 5 - 9, 2011, Houston, Texas, USA. This workA Hybrid Radio Frequency and Broadcast Visible Light Communication System Michael B. Rahaim , Anna

214

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

215

Radio frequency telemetry system for sensors and actuators  

NASA Technical Reports Server (NTRS)

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 powering/receiving device. Such technology has many applications, but is especially useful in the biomedical area.

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

2003-01-01

216

Radio Frequency Telemetry System for Sensors and Actuators  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

217

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 employ over 70 power electrical and power electronic engineers and technicians. The department supplies power to the JET and MAST nuclear fusion experiments at Culham. Culham is fed from the grid at 400k

218

Authentication of Radio Frequency Identification Devices Using Electronic Characteristics  

ERIC Educational Resources Information Center

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…

Chinnappa Gounder Periaswamy, Senthilkumar

2010-01-01

219

Radio-frequency quadrupole: General properties and specific applications  

Microsoft Academic Search

The general properties of radio frequency quadrupole accelerators are reviewed and beam dynamics simulation results are presented for their use in a variety of accelerating systems. 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 are included. Bibtex entry for this abstract Preferred format for

R. H. Stokes; K. R. Crandall; R. W. Hamm; F. J. Humphry; R. A. Jameson; E. A. Knapp; J. M. Potter; G. W. Rodenz; J. E. Stovall; D. A. Swenson

1980-01-01

220

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...

221

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...

222

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...

223

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...

224

Localized radio frequency communication using asynchronous transfer mode protocol  

DOEpatents

A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.

Witzke, Edward L. (Edgewood, NM); Robertson, Perry J. (Albuquerque, NM); Pierson, Lyndon G. (Albuquerque, NM)

2007-08-14

225

Development of radio frequency treatments for dried pulses  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chemical fumigants are typically used to disinfest dried pulses of insect pests before shipment to importing countries, but the industry is exploring non-chemical alternatives. One possible alternative is the use of radio frequency (RF) energy to rapidly heat product to insecticidal levels. The cowp...

226

Passive chip-less millimeter wave Radio Frequency Identification  

Microsoft Academic Search

This article describe a passive, chip-less millimeter wave radio frequency identification (RFID) technology that uses an array of microscopic resonant elements implanted into the paper, cardboard, and plastic substrates typically used for an optical label, such as a barcode. When illuminated with RF energy, the resonant array provides a ldquoRF Fingerprintrdquo based on parameters including density, thickness, and orientation of

Andrew Wu; Kamran Mahbobi; Houman Ghajari; Yuriy Mykula; Brian Woods

2008-01-01

227

Radio frequency and infrared drying of sized textile warp yarns  

SciTech Connect

Drying sized textile warp yarns without contacting the warp is easily accomplished by either radio frequency or infrared techniques. Although the process is more expensive than conventional drying, the substantial savings accrued during subsequent weaving and finishing of the cloth can help keep the US textile industry competitive and support electrical load. 5 refs., 8 figs., 14 tabs.

Ruddick, H.G. (West Point Foundry and Machine Co., GA (USA))

1990-11-01

228

Modification of the DSN radio frequency angular tropospheric refraction model  

NASA Technical Reports Server (NTRS)

The previously derived DSN Radio Frequency Angular Tropospheric Refraction Model contained an assumption which was subsequently seen to be at a variance with the theoretical basis of angular refraction. The modification necessary to correct the model is minor in that the value of a constant is changed.

Berman, A. L.

1977-01-01

229

A radio frequency compensated emissive probe  

NASA Astrophysics Data System (ADS)

We discuss a technique for using an emissive probe to measure accurately the time-invariant plasma potential in a rf generated plasma, usually used in plasma processing. With an emissive probe, a short length of filament, heated to thermionic emission, is immersed in the plasma. We have introduced into each lead of the filament two LC circuits, one resonant at 13.6 MHz, the fundamental rf frequency, and the other at 27.2 MHz, the first harmonic. With the LC circuits in place a single peak of di/dv versus v occurs with a maximum at the time-invariant plasma potential. The inflection point method of measuring this potential described by Smith, Hershkowitz, and Coakley [Rev. Sci. Instrum. 50, 210 (1979)] in a dc plasma is now operative. The estimated error in measuring this potential is ±3.5%.

Kang, Jungwon; Carlile, Robert N.; O'Hanlon, John F.

1996-05-01

230

Adaptive Beam Steering Smart Antenna System for Ultra-High-Frequency Radio Frequency Identification Applications  

Microsoft Academic Search

Smart antenna technologies have been widely applied in many wireless communication systems due to performance enhancement in terms of data range, coverage and capacity. Up to now, not much effort was devoted for ultra high-frequency (UHF) radio frequency identification (RFID) applications mainly due to the relatively large size of the antenna element. In this paper, we present a compact-sized electrically

Ting-Jui Huang; Pei-Hsuan Pan; Heng-Tung Hsu

2012-01-01

231

78 FR 49529 - Radio Frequency Wireless Technology in Medical Devices; Guidance for Industry and Food and Drug...  

Federal Register 2010, 2011, 2012, 2013, 2014

...formerly Docket No. 2006D-0504) Radio Frequency Wireless Technology in Medical...availability of the guidance entitled ``Radio Frequency Wireless Technology in Medical...to the incorporation and integration of radio frequency (RF) wireless technology...

2013-08-14

232

Dowsing can be interfered with by radio frequency radiation.  

PubMed

The soil radiation, watercourses and ores have been located for centuries by sensitive persons, dowsers. An ideomotoric explanation of the dowsing reaction, with no physical interaction, has been accepted. Our present re-analyses of some such results have shown, that there could be a physical phenomenon connecting the human reactions in field experiments, where the test subjects walked or were sitting in a slow-moving car, with the windows covered, and a dowsing rod in their hands was recorded. The correlations between the reaction points by test subjects in the moving car and the points by walking along the same path were highly significant. The correlation was not seen in all test locations. The distance between the test location and the radio tower, and the incidence angle of the transmitted radio wave, possibly had an effect on results. We hypothesize that the experiments carried out in the 20th century were interfered with by man-made radio frequency radiation, mainly FM radio and TV broadcasting, as test subjects' bodies absorbed the radio waves and unconscious hand movement reactions took place following the standing waves or intensity variations due to multipath propagation. PMID:22365422

Huttunen, Paavo; Niinimaa, Ahti; Myllylä, Risto

2012-04-01

233

ELF radio signals produced in the auroral ionosphere by non-linear demodulation of signals from high-power amplitude-modulated transmitters  

NASA Astrophysics Data System (ADS)

ELF and VLF radio signals recorded in the afternoon and early morning (local time) between March 24 and April 4, 1979, in Northern Scandinavia are discussed. In addition to signals of natural origin, timing signals (six pips of equal duration of 105 + or - 8 ms, at 1 kHz + or - 0.5 Hz) were observed on the hour UT. It was found that such signals occur only on days of relatively high geomagnetic activity during enhanced auroral electrojet activity. These signals are thought to be generated by nonlinear demodulation (self-detection) of signals from two or more amplitude modulated transmitters in the USSR, operating at 173, 200, 236, 263, and 657 kHz. The simplest explanation for the observations is thought to be provided by the three transmitters operating at 173 kHz.

Rycroft, M. J.; Cannon, P. S.; Turunen, T.

234

Numerical studies of current generation by radio-frequency traveling waves  

E-print Network

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

Karney, Charles

235

A Two-Dimensional Model of Chemical Vapor Infiltration With Radio Frequency Heating  

E-print Network

A Two-Dimensional Model of Chemical Vapor Infiltration With Radio Frequency Heating Vikas Midha with radio frequency heating. The model included equations for energy transport, multicomponent mass-consistently the power absorbed by the preform from a radio frequency induction coil. The model equations were solved

Economou, Demetre J.

236

Ultrasound Monitoring of InVitro Radio Frequency Ablation by Echo  

E-print Network

characteristic nterstitial thermal ablation methods, including radio frequency and laser approaches, haveUltrasound Monitoring of InVitro Radio Frequency Ablation by Echo Decorrelation Imaging T. Douglas imaging for mapping and characterization of tissue effects caused by radio frequency ablation (RFA

Mast, T. Douglas

237

Radio frequency communication system utilizing radiating transmission lines  

DOEpatents

A radio communication system for use in tunnels, mines, buildings or other shielded locations in which a pair of radiating transmission lines (30), (31) extend through such location in spaced coextensive relation to each other. Each transmission line (30), (31) has at least one unidirectional amplifier (32), (33) interposed therein with the sense of the unidirectional amplifier (32) of one transmission line (30) being opposite to the sense of the unidirectional amplifier (33) of the other transmission line (31). Each of the amplifiers (32), (33) has a gain which is less than the coupling loss between the transmission lines (30), (31). Two or more mobile transceivers (35) in the location served by the system are coupled to the transmission lines (30), (31) by electromagnetic wave propagation in space in order to communicate directly with each other at a given radio frequency within the frequency range of the system.

Struven, Warren C. (San Carlos, CA)

1984-01-01

238

Radio frequency analog electronics based on carbon nanotube transistors.  

PubMed

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

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

2008-02-01

239

Pressure micro-sensor based on Radio-Frequency transducer  

Microsoft Academic Search

A new type of pressure micro-sensors is reported in this communication. It is based on the use of a Radio-Frequency transducer. The pressure to be measured is applied on a silicon membrane located in the close vicinity of a coplanar millimeter-wave resonator: when varying the applied pressure, the distance between the membrane and the planar resonator is modified and consequently,

Mohamed Mehdi Jatlaoui; Patrick Pons; Herve Aubert

2008-01-01

240

Radio frequency interference from near-earth satellites  

NASA Technical Reports Server (NTRS)

A pessimistic statistical model was developed for predicting the extent of radio frequency interference (RF1). Based on the assumptions underlying the model, DSN S-band operations can expect one RF1 interruption every 4.1 days, with the average incident lasting 24 s. This implies that 52 or more such satellites, with uncorrelated orbital trajectories, will cause in excess of 5 min of RF1 per day at a DSN station.

Levitt, B. K.; Lesh, J. R.

1977-01-01

241

Biological Effects of High Peak Power Radio Frequency Pulses  

Microsoft Academic Search

\\u000a During the early years of research on the potential hazards of Radio Frequency (RF) radiation, scientists have considered\\u000a the possibility that a pulsed RF field could produce effects other than those produced by continuous-wave (CW) radiation at\\u000a the same average power. Recent developments in high peak power pulsed microwave systems have rekindled interest in exploring\\u000a potential biological effects of high

Shin-Tsu Lu; John O. Lorge

242

Corneal reshaping by radio frequency current: numerical model studies  

NASA Astrophysics Data System (ADS)

The cornea may be reshaped to correct for hyperopia by selective shrinkage of collagen in the stroma using radio frequency (RF) current from a needle electrode. Pulsed current is used to maximize therapeutic effect while minimizing radiating thermal damage. Finite difference numerical models of the electric fields and resulting thermal events were used to study the process parameters. The models were calibrated by comparison to histologic data using predicted and measured loss of birefringence in collagen as the standard of comparison.

Pearce, John A.

2001-06-01

243

Chaos generated noise in radio frequency SQUID magnetometers  

SciTech Connect

In this paper we consider from a theoretical viewpoint the interaction between a single macroscopic quantum object (a SQUID ring) and a classical circuit apparatus (a radio frequency resonant circuit). We demonstrate that chaotic solutions exist for this coupled system over a wide range of parameters and that this chaotic behaviour is determined by the quantum state of the SQUID ring. {copyright} {ital 1996 American Institute of Physics.}

Diggins, J.; Ralph, J.F.; Spiller, T.P.; Clark, T.D.; Prance, H.; Prance, R.J. [Physics Division, School of Mathematical and Physical Sciences, University of Sussex, Brighton, Sussex, BN1 9QH (United Kingdom); Brouers, F. [Physics Department, University of Liege, Sart Tilman, Liege 4000 (Belgium)

1996-05-01

244

Optical beat-note frequency stabilization between two lasers using a radio frequency interferometer in the gigahertz frequency band  

NASA Astrophysics Data System (ADS)

A beat-note frequency stabilization system using a distributed-feedback laser and external cavity laser diode has become a very important technique for laser spectroscopy, where highly stabilized high-frequency beat notes are required. We have developed a simple and versatile system capable of stabilizing the high-frequency beat notes (3 to 11 GHz) of two lasers using a delayed radio frequency self-heterodyne interferometer and have confirmed its basic operation. The frequency stability of the obtained beat notes is higher than 1 MHz in the 3- to 11-GHz frequency range with an average time of 20 s.

Uehara, Tomoyuki; Tsuji, Kenichiro; Hagiwara, Kohei; Onodera, Noriaki

2014-12-01

245

Multiplexing of Radio-Frequency Single Electron Transistors  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

246

Radio frequency seismic gathering system employing an airborne blimp  

SciTech Connect

The central station of a radio-connected seismic surveying system uses a tethered blimp carrying an antenna and an electronics package including a dc voltage/rf decoupler, a variable dc controlled preamplifier, a p-i-n diode switch for changing the antenna from receive to transmit operation, a transmitter and modulator and a battery. An rf coaxial cable to ground provides means for controlling the preamplifier gain and for switching the central station to the transmit mode by using appropriate dc signals. In the receive mode, the cable carries detected field unit seismic signals, which are detected by the blimp-carried antenna and preamplified by the blimp preamplifier, to the ground for suitable recording and further processing in the ground portion of the central station. An audio channel can also be modulated onto the transmit carrier of approximately 70 mhz to provide voice communications via the blimp electronics, if desired. Both the ground portion and the blimp portion of the central station are packaged for helicopter transporting.

Imm, R.A.; McDavid, W.T.; Mckeever, J.M.

1980-11-25

247

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

E-print Network

) Smart munitions Secure Communications Explosive/Biological weapon Detection Altimeters Remote sensing.g. Low earth orbit mobile systems, Steerable phased-array antennas For footprint control) Remote sensing Station-keeping #12;E4.18 Radio Frequency Electronics Copyright © 2006 Dr Stepan Lucyszyn Civil

Papavassiliou, Christos

248

Physical properties of conventional explosives deduced from radio frequency emissions  

SciTech Connect

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.

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

2008-01-01

249

A very low frequency radio astronomy observatory on the Moon  

NASA Technical Reports Server (NTRS)

Because of terrestrial ionospheric absorption, very little is known of the radio sky beyond 10 m wavelength. An extremely simple, low cost very low frequency radio telescope is proposed, consisting of a large array of short wires laid on the lunar surface, each wire equipped with an amplifier and a digitizer, and connected to a common computer. The telescope could do simultaneous multifrequency observations of much of the visible sky with high resolution in the 10 to 100 m wavelength range, and with lower resolution in the 100 to 1000 m range. It would explore structure and spectra of galactic and extragalactic point sources, objects, and clouds, and would produce detailed quasi-three-dimensional mapping of interstellar matter within several thousand parsecs of the Sun.

Douglas, James N.; Smith, Harlan J.

1988-01-01

250

Detection of NMR signals with a radio-frequency atomic magnetometer I.M. Savukov 1  

E-print Network

Detection of NMR signals with a radio-frequency atomic magnetometer I.M. Savukov 1 , S.J. Seltzer of proton NMR signals with a radio-frequency (rf) atomic magnetometer tuned to the NMR frequency of 62 kHz. High-frequency operation of the atomic magnetometer makes it relatively insensitive to ambient magnetic

Romalis, Mike

251

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

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

Shull, Kenneth R.

252

Ground based studies of auroral medium frequency burst radio emissions  

NASA Astrophysics Data System (ADS)

MF burst is an impulsive auroral radio emission at ˜1.3-4.5 MHz commonly detected by ground-based instruments for a few minutes at substorm onsets. The Dartmouth College MF radio interferometer at Toolik Field Station, Alaska (68.51° invariant latitude) measured spectra, amplitudes, and directions of arrival (DOA) of naturally occurring auroral radio waves between between 0.1 and 5 MHz beginning in the fall of 2006. DOA case studies reveal temporal and spatial coincidence with expanding auroral arcs for substorms observed on 23 March and 20 November 2007. DOA statistical studies show that MF bursts are observed predominantly from the south and east of Toolik, which can be attributed to propagation effects. Statistical and case studies of DOA data of MF burst show that higher-frequency components of MF burst arrive at higher elevation angles than lower-frequency components. Ray-tracing analysis shows that this trend implies that sources of the higher-frequency components of the MF burst are at higher altitudes than those of the lower-frequency components. Full resolution observations show that MF burst consists of a superposition of "structured" (showing sharp time-frequency edges/features), and "unstructured" (more diffuse) features. Structured features show a repeatable frequency-time structure in which a leading edge decreases, from a well-defined upper bound, in frequency of 100s of kHz over ˜100ms. Despite several suggested theories, the exact generation mechanism for MF burst still remains a mystery. The foremost theory suggests MF burst originates from mode conversion of Langmuir or upper hybrid waves excited over a range of altitudes in the bottomside F-region. However, analysis of plasmas with two electron components implies existence of additional normal modes, called the electron acoustic (EA) and electron cyclotron sound (ECS) modes, which have previously been suggested to play a role in MF burst. Further analytical calculations, using WHAMP and other dispersion solving codes, suggest that instability of these modes in the presence of an auroral electron distribution is possible. The same analysis suggests that LO-cannot be directly excited. The above recent experimental and analytical studies combined with a discussion on viable normal wave modes available in the auroral ionosphere allow us to constrain potential modes of generation for MF burst.

Bunch, Nicholas L.

253

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

PubMed

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

Michael, Sarah; Gartrell, Brett; Hunter, Stuart

2013-07-01

254

A CMOS dual-channel, 100MHz to 1.1GHz transmitter for cable applications  

Microsoft Academic Search

A dual-channel wide-band transmitter for cable applications is presented that has more than a decade frequency coverage. The chip consists of two parallel transmitters that are both fully operational from 100 MHz up to 1.1 GHz. Using a single-ended current-mode output topology, the radio-frequency (RF) output signals are lossless combined by summing the output currents. The third-order harmonic of the

Marc A. F. Borremans; C. R. C. De Ranter; M. S. J. Steyaert

1999-01-01

255

47 CFR 90.463 - Transmitter control points.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Transmitter control points. 90.463 Section 90.463 Telecommunication...PRIVATE LAND MOBILE RADIO SERVICES Transmitter Control § 90.463 Transmitter control points. (a) A control operator is...

2010-10-01

256

47 CFR 90.463 - Transmitter control points.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Transmitter control points. 90.463 Section 90.463 Telecommunication...PRIVATE LAND MOBILE RADIO SERVICES Transmitter Control § 90.463 Transmitter control points. (a) A control operator is...

2011-10-01

257

Simultaneous occupational exposure to FM and UHF transmitters.  

PubMed

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

Vali?, Blaž; Kos, Bor; Gajšek, Peter

2012-01-01

258

A radio-frequency quadrupole accelerator longitudinal field stabilizer  

SciTech Connect

The fields in a 600-MHz model of a radio-frequency quadrupole (RFQ) accelerator have been longitudinally stabilized over 86% of its length. The stabilizing elements consist of four external transverse electromagnetic (TEM) lines. Each line is coupled to the RFQ by two magnetic loops attached to voltage maxima of the TEM line. These resonant lines stabilize the RFQ fields by providing an alternate longitudinal power flow path in the RFQ. Stabilization depends on the TEM line Q and the TEM line RFQ coupling. Each stabilizer coupling-loop location in the RFQ needs to be fully azimuthally stabilized. Substantial coupling between stabilizer elements destroys stabilization. 3 refs., 13 figs., 2 tabs.

Gray, E.R.; Spalek, G.; Shapiro, A.

1988-01-01

259

The radio-frequency impedance of individual intrinsic Josephson junctions  

SciTech Connect

We have measured the response of an array of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} intrinsic Josephson junctions to irradiation at 3 GHz. By measuring the dependence of the switching current upon the radio-frequency current for five of the junctions in the array we show quantitatively that the junctions have identical impedances at 3 GHz, this impedance being given by the inverse of the slope of the current-voltage characteristics.

Leiner, Johannes; Saleem, Sajid; Fenton, J. C.; Warburton, P. A. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Yamamoto, Takashi; Kadowaki, Kazuo [Institute of Materials Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

2009-12-21

260

Diffuse ?-mode atmospheric pressure radio-frequency discharge in neon  

NASA Astrophysics Data System (ADS)

In this work, a radio-frequency (RF) atmospheric pressure glow discharge burning in neon between planar metal electrodes is achieved for the first time. The RF discharge can operate in two stable modes: in a diffuse ?-mode with uniformly covered electrode surfaces and in a constricted ?-mode. Similarities are revealed when the discharge is compared against the RF atmospheric pressure glow discharge in helium, namely both discharges show a discontinuity and a hysteresis in the current-voltage characteristic at the mode transition; the spatio-temporal profiles of the light emission in the ?-mode from neon, helium and atomic oxygen are also similar.

Navrátil, Z.; Dosoudilová, L.; Josepson, R.; Dvo?ák, P.; Trunec, D.

2014-08-01

261

Plasma plume propagation characteristics of pulsed radio frequency plasma jet  

SciTech Connect

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.

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

262

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

PubMed

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

Kolokathi, Aikaterini; Rallis, Panagiotis

2013-01-01

263

Hollow metal target magnetron sputter type radio frequency ion source  

SciTech Connect

A 70 mm diameter 70 mm long compact ion source equipped with a hollow sputtering target has been designed and tested. The hollow sputtering target serves as the radio frequency (RF) plasma excitation electrode at 13.56 MHz. A stable beam of Cu{sup +} has been extracted when Ar was used as the discharge support gas. In the extracted beam, Cu{sup +} had occupied more than 85% of the total ion current. Further increase in Cu{sup +} ions in the beam is anticipated by increasing the RF power and Ar pressure.

Yamada, N., E-mail: mwada@mail.doshisha.ac.jp; Kasuya, T.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyoto 610–0321 (Japan)] [Graduate School of Science and Engineering, Doshisha University, Kyoto 610–0321 (Japan); Tsubouchi, N. [Kansai Institute, Advanced Industrial Science and Technology, Osaka 563–8577 (Japan)] [Kansai Institute, Advanced Industrial Science and Technology, Osaka 563–8577 (Japan)

2014-02-15

264

Automatic calibration of modulated fractional-N frequency synthesizers  

E-print Network

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 ...

McMahill, Dan

2001-01-01

265

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

SciTech Connect

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.

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

2010-05-03

266

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

Microsoft Academic Search

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%,

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

2004-01-01

267

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

E-print Network

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 ...

Jackson, David A. (David Alexander)

2005-01-01

268

Radio frequency based label-free detection of glucose.  

PubMed

We investigated the frequency based mediator-free glucose sensor in the radio-frequency (RF) range. Frequency dependent power signal showed clear dependence on the glucose concentration with free enzymatic condition. Also, the passive electrical components such as the resistance, inductance, shunt conductance, and capacitance were extracted based on the transmission line model for further analysis. These various parameters proposed by the signal processing provided more effective verification for instant multi-components in-situ readings without any added supporters. Additionally the residual signal (RS), impedance (Z), and propagation constant (?) were also calculated from measured S-parameters for glucose analysis. These parameters basically showed amplitude variation and interestingly, some parameters such as inductance and impedance showed frequency shift of resonance dip. The results support that the frequency based sensing technique including the parameter based analysis can enable effective multi-dimensional detection of glucose. Moreover, this technique showed that glucose sensing is also possible over a diabetic patient's serum. PMID:24269756

Park, Hyunggoo; Seo Yoon, Hyung; Patil, Umakant; Anoop, Rani; Lee, Juho; Lim, Juhwan; Lee, Woonhyoung; Chan Jun, Seong

2014-04-15

269

Imaging radio-frequency fields using a scanning SQUID microscope  

SciTech Connect

Using a liquid-nitrogen-cooled scanning SQUID magnetic microscope, we have developed a technique for broadband imaging of radio-frequency (rf) and microwave fields with a spatial resolution of about 15 [mu]m. We have produced images of the amplitude of 50 MHz fields with an rms noise of 2.6 nT and a 300 [mu]m/s scan rate. Detection is accomplished by using the nonlinearity of the voltage-flux characteristic of the SQUID to rectify the rf fields. Our present technique is limited by cavity mode resonances in the SrTiO[sub 3] substrate of our SQUID sensor. Using a small excitation probe, we have directly imaged these resonances at frequencies up to about 12.5 GHz.

Black, R.C.; Wellstood, F.C. (Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States)); Dantsker, E.; Miklich, A.H.; Koelle, D.; Ludwig, F.; Clarke, J. (Department of Physics, University of California and Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

1995-03-06

270

Ground and space observations of medium frequency auroral radio emissions  

NASA Astrophysics Data System (ADS)

The auroral zone is a rich source of natural radio emissions that can be observed in space and at ground-level. By studying these waves, scientists can gain insight into the plasma processes that generate them and use the near-Earth space environment as a large-scale plasma physics laboratory. This thesis uses both ground-level and in situ observations to study two kinds of natural radio emissions. First, we report observations of a new kind of auroral radio emission. The waves have frequencies ranging from 1.3-2.2 MHz, bandwidths ranging from 90-272 kHz, and durations ranging from 16-355 s. Spectral analysis of the waveform data has revealed that the emission has a complex combination of at least three kinds of fine structures. For model auroral electron distributions, calculations indicate that Langmuir waves could be excited at frequencies consistent with observations. The remainder of the thesis discusses auroral medium frequency (MF) burst, an impulsive, broadband natural radio emission observed at ground-level within a few minutes of local substorm onset. LaBelle [2011] proposed that MF burst originates as Langmuir/Z-mode waves on the topside of the ionosphere that subsequently mode convert to L-mode waves and propagate to ground-level. Using continuous waveform measurements and combined observations with the Sondrestrom Incoherent Scatter Radar, we have performed two tests of this mechanism. The results of these tests are consistent with the mechanism described in LaBelle [2011]. A survey of 8,624 half-orbits of the DEMETER spacecraft has revealed 68 observations of bursty MF waves. We have compared the wave properties of these waves to those of MF burst and have found that although it is uncertain, the balance of the evidence suggests that the bursty MF waves observed with DEMETER are the same phenomenon as the ground-level MF burst. Finally, we have used numerical simulations to model both the fine structure of MF burst and to estimate the attenuation the waves would experience due to Landau damping on the topside ionosphere and mode conversion on the bottomside ionosphere. The amount of Landau damping is sensitive to the ratio of secondary to background electrons nse/ne0. Ignoring collisional damping in the lower ionosphere, these calculations suggest that for nse/n e0<0.4%, 0.01-45% of the initial Langmuir wave power would reach ground-level. The above experimental and numerical studies constrain the conditions under which MF burst could plausibly originate as Langmuir/Z-mode waves on the topside of the ionosphere.

Broughton, Matthew C.

271

Radio-frequency identification: its potential in healthcare.  

PubMed

Radio-frequency identification (RFID) technology is just starting to make inroads into healthcare. RFID uses radio-frequency tags attached to people or objects to provide identification, tracking, security, and other functions that fall under the general heading of automatic identification and data capture (AIDC). In the retail supply chain, RFID is already well established as a way to reduce theft and track objects from manufacture through shipment to delivery. In healthcare, basic RFID is already being used to track patients for anti-elopement and anti-abduction programs. As more sophisticated systems move into hospitals, RFID is also beginning to see use to provide more extensive patient identification than traditional bar coding can, and to track and locate capital equipment within the hospital. In years to come, RFID could be used for a variety of applications, including tracking and matching blood for transfusions, tracking pharmaceuticals, and combating the counterfeiting of medical products. RFID may ultimately be used for many of the functions currently carried out using bar coding--but not until the cost of RFID comes down. For the foreseeable future, the two technologies are likely to be used in tandem in many hospitals. In this article, we describe the components and operation of RFID systems and detail the different ways in which these systems are being used, and could be used, in hospitals. PMID:16048121

2005-05-01

272

Hermetic aluminum radio frequency interconnection and method for making  

DOEpatents

The present invention provides a light-weight, hermetic coaxial radio-frequency (RF) interconnection having an electrically conductive outer housing made of aluminum or an aluminum alloy, a central electrical conductor made of ferrous or non-ferrous material, and a cylinder of dielectric material comprising a low-melting-temperature, high-thermal-expansion aluminophosphate glass composition for hermetically sealing between the aluminum-alloy outer housing and the ferrous or non-ferrous center conductor. The entire RF interconnection assembly is made permanently hermetic by thermally fusing the center conductor, glass, and housing concurrently by bringing the glass to the melt point by way of exposure to an atmospheric temperature sufficient to melt the glass, less than 540.degree. C., but that does not melt the center conductor or the outer aluminum or aluminum alloy housing. The composition of the glass used is controlled to provide a suitable low dielectric constant so that an appropriate electrical characteristic impedance, for example 50 ohms, can be achieved for an electrical interconnection that performs well at high radio frequencies and also provides an interconnection maintaining a relatively small physical size.

Kilgo, Riley D. (Albuquerque, NM); Kovacic, Larry (Albuquerque, NM); Brow, Richard K. (Rolla, MO)

2000-01-01

273

In situ observations of medium frequency auroral radio emissions  

NASA Astrophysics Data System (ADS)

The auroral ionosphere is a region rich with plasma waves that can be studied both in space and on the ground. These waves may mediate energy exchange between particle populations and provide information about the local plasma properties and boundaries. Auroral medium frequency (MF) burst is an impulsive radio emission observed at ground-level from 1.3-4.5 MHz that is associated with local substorm onset. There have been two recent reports of impulsive, broadband, MF waves at high latitudes. Burchill and Pfaff [2005] reported observations from the FAST satellite of impulsive, broadband, MF and low frequency (LF) radio waves. Using data from the DEMETER satellite, Parrot et al. [2009] surveyed MF waves caused by lightning. This study did show a high-latitude population of MF waves. We investigate whether the waves observed by these two satellites are related to auroral MF burst. Using FAST satellite burst mode electric field data from high-latitude (> 60 degrees magnetic), low-altitude (< 1000 km) intervals of moderate to large geomagnetic activity (Kp > 3) from 1996-2002, we have found forty-four examples of impulsive MF waves, all of which are associated with impulsive LF waves. Although MF burst and the waves observed by FAST have similar spectral signatures, they have different magnetic local time dependencies, which suggests that they may be unrelated. A study of MF waves observed at high latitude by DEMETER is ongoing. In situ observations of MF burst could provide crucial information about this heretofore unexplained natural radio emission.

Broughton, M.; Labelle, J. W.; Pfaff, R. F.; Parrot, M.; Yan, X.; Burchill, J. K.

2013-12-01

274

Differential frequency-dependent regulation of transmitter release by endogenous nitric oxide at the amphibian neuromuscular synapse.  

PubMed

Nitric oxide (NO) is a potent neuromodulator in the CNS and PNS. At the frog neuromuscular junction (nmj), exogenous application of NO reduces neurotransmitter release, and NO synthases (NOSs), the enzymes producing NO, are present at this synapse. This work aimed at studying the molecular mechanisms by which NO modulates synaptic efficacy at the nmj using electrophysiological recordings and Ca(2+)-imaging techniques. Bath application of the NO donors S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside decreased end plate potential (EPP) amplitude as well as the frequency of miniature EPPs but not their amplitude. Ca(2+) responses elicited in presynaptic terminals by single action potentials were unaffected by NO, but responses evoked by a short train of stimuli were increased. Tonic endogenous production of NO was observed as suggested by the increase in EPP amplitude by bath application of the NO scavenger hemoglobin and the neuronal NOS inhibitor 3-bromo-7-nitroindazole sodium salt. A soluble guanylate cyclase inhibitor, 6-anilino-5,8-quinolinedione (LY-83583), increased EPP amplitude and occluded the effects of the NO donor, suggesting that NO acts via a cGMP-dependent mechanism. High-frequency-induced depression was reduced in the presence of the NO scavenger but not by LY-83583. However, adenosine-induced depression was significantly reduced after bath perfusion of SNAP and in the presence of LY-83583. Our results indicate that NO regulates transmitter release and adenosine-induced depression via a cGMP-dependent mechanism that occurs after Ca(2+) entry and that high-frequency-induced synaptic depression is regulated by NO in a cGMP-independent manner. PMID:11160378

Thomas, S; Robitaille, R

2001-02-15

275

Radio-frequency identification of surgical sponges in the abdominal cavity of pigs  

PubMed Central

Background Counting the sponges is an important step in surgical procedures. A miscount may impact the patient's health, and it also has legal implications for the surgeon. This is an experimental study evaluating radio-frequency technology used in the perioperative period to identify surgical sponges left in the peritoneal cavity of swine. Methods Radio-frequency labeled-disc identification tags were sewn into 40 surgical towels. Twenty labels had the ability to emit radio-frequency waves, and 20 labels were inert to radio-frequency identification. Twenty adult pigs that underwent laparotomy and randomly received two surgical sponges were scanned by a radio-frequency identification antenna. Results This method presented a positive predictive value of 100% and 100% specificity and sensitivity, as all of the tagged surgical sponges were detected. Conclusion Radio-frequency identification has been proved to be a useful method for the identification of surgical sponges within the abdominal cavities of swine. PMID:25568782

Wiederkehr, Julio Cesar; Gama, Ricardo R.; Wiederkehr, Henrique A.; Stelmasuk, Kleber; Carvalho, Caroline A.; Wiederkehr, Barbara A.

2014-01-01

276

Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance  

E-print Network

Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance S 20 November 2006 A radio-frequency tunable atomic magnetometer is developed for detection of nuclearHz 14 N NQR frequency of ammonium nitrate. A potential application of the magnetometer is detection

Romalis, Mike

277

A novel radio frequency assisted heat pump dryer  

SciTech Connect

This paper compares an experimental heat pump batch dryer with the implementation of volumetric Radio Frequency (RF) heating, in the combination drying of crushed brick particulate. Results are presented showing overall improvements in drying. A simplified mathematical drying model including the RF energy source has been developed using mass and energy conservation, confirming the experimental results. Drying is a widespread, energy intensive industrial unit operation. The economics of a drying process operation largely depend upon the dryers performance and ultimately the cost of energy consumption. To enhance the performance of a drying system, the damp air stream that exits the drying chamber can be recycled to reclaim the enthalpy of evaporation that it carries, by using a heat pump (Hodgett, 1976). However, because the medium that dries is still warm air, this system also suffers from heat transfer limitations, particularly towards the falling drying rate period. Such limitations in drying performance can be overcome with the use of Radio Frequency (RF) energy which generates heat volumetrically within the wet material by the combined mechanisms of dipole rotation and conduction effects which speeds up the drying process (Metaxas et al, 1983). Despite the clear advantages that heat pumps and high frequency heating offer for drying, the combination of these two techniques until recently has not been studied (Kolly et al, 1990; Marshall et al, 1995).A series of experiments carried out comprising a motor driven heat pump which was retro-fitted with the ability of imparting RF energy into a material at various stages of the drying cycle are described and compared with a mathematical model.

Marshall, M.G.; Metaxas, A.C.

1999-09-01

278

Minimizing the effects of radio-frequency heating in multidimensional NMR experiments.  

PubMed

Application of radio-frequency power in multidimensional NMR experiments can significantly increase the sample temperature compared to that of the surrounding gas flow. Radio-frequency heating effects become more severe at higher magnetic field strengths and ionic strengths. The effects are particularly noticeable for experiments that utilize 1H and/or 13C isotropic mixing and broadband decoupling. If radio-frequency power is applied during the systematically increasing evolution period t1, the sample temperature can change with t1 and thereby cause line-shape distortions. Such distortions are easily avoided by ensuring that the average radio-frequency power remains constant during the entire experiment. PMID:8111234

Wang, A C; Bax, A

1993-11-01

279

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2013-07-22

280

47 CFR 87.133 - Frequency stability.  

Code of Federal Regulations, 2011 CFR

...20 Hz. 9 Where specific frequencies are not assigned to radar stations, the bandwidth occupied by the emissions of such...10 Hz. (2) All aircraft stations—20 Hz. (d) For radar transmitters, except non-pulse signal radio...

2011-10-01

281

47 CFR 87.133 - Frequency stability.  

Code of Federal Regulations, 2012 CFR

...20 Hz. 9 Where specific frequencies are not assigned to radar stations, the bandwidth occupied by the emissions of such...10 Hz. (2) All aircraft stations—20 Hz. (d) For radar transmitters, except non-pulse signal radio...

2012-10-01

282

47 CFR 87.133 - Frequency stability.  

Code of Federal Regulations, 2013 CFR

...20 Hz. 9 Where specific frequencies are not assigned to radar stations, the bandwidth occupied by the emissions of such...10 Hz. (2) All aircraft stations—20 Hz. (d) For radar transmitters, except non-pulse signal radio...

2013-10-01

283

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

SciTech Connect

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.

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

284

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

SciTech Connect

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{sup +}) beam, we tested it by accelerating both the proton (H{sup +}) and D{sup +} beams. The RFQ was operated in pulsed mode and accelerated both H{sup +} and D{sup +} 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.

Rao, S. V. L. S., E-mail: svlsrao@gmail.com; Jain, Piyush; Pande, Rajni; Roy, Shweta; Mathew, Jose V.; Kumar, Rajesh; Pande, Manjiri; Krishnagopal, S.; Gupta, S. K.; Singh, P. [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)] [Ion Accelerator Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2014-04-15

285

Radio frequency identification enabled wireless sensing for intelligent food logistics.  

PubMed

Future technologies and applications for the Internet of Things (IoT) will evolve the process of the food supply chain and create added value of business. Radio frequency identifications (RFIDs) and wireless sensor networks (WSNs) have been considered as the key technological enablers. Intelligent tags, powered by autonomous energy, are attached on objects, networked by short-range wireless links, allowing the physical parameters such as temperatures and humidities as well as the location information to seamlessly integrate with the enterprise information system over the Internet. In this paper, challenges, considerations and design examples are reviewed from system, implementation and application perspectives, particularly with focus on intelligent packaging and logistics for the fresh food tracking and monitoring service. An IoT platform with a two-layer network architecture is introduced consisting of an asymmetric tag-reader link (RFID layer) and an ad-hoc link between readers (WSN layer), which are further connected to the Internet via cellular or Wi-Fi. Then, we provide insights into the enabling technology of RFID with sensing capabilities. Passive, semi-passive and active RFID solutions are discussed. In particular, we describe ultra-wideband radio RFID which has been considered as one of the most promising techniques for ultra-low-power and low-cost wireless sensing. Finally, an example is provided in the form of an application in fresh food tracking services and corresponding field testing results. PMID:24797140

Zou, Zhuo; Chen, Qiang; Chen, Qing; Uysal, Ismail; Zheng, Lirong

2014-06-13

286

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

PubMed

In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600?MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10?g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances. PMID:24523232

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

2014-05-01

287

The Radio Frequency Heating of Magnum-psi  

SciTech Connect

Magnum-psi is a linear device to be constructed at the FOM-Rijnhuizen institute and designed to produce plasmas allowing the study of plasma-surface interaction processes relevant to the ITER divertor. The plasma cross-section will be about 100 cm{sup 2}, the plasma density around 10{sup 20} m{sup -3} and the temperature around 3eV. The plasma will be confined by a strong magnetic field (up to 3T). In order to reach the adequate temperature and power flux, it is foreseen to heat the plasma with radio-frequency power, typically at the level of 100kW. In this paper, we investigate which heating system would match the requirements of the experiment.

Koch, R. [LPP-ERM/KMS, Euratom-Belgian State Association (Belgium); Messiaen, A.M. [LPP-ERM/KMS, Euratom-Belgian State Association (Belgium); Lopes Cardozo, N.J. [FOM-Institute for Plasma Physics Rijnhuizen, Association Euratom-FOM (Netherlands)

2005-01-15

288

Design and fabrication of the BNL radio frequency quadrupole  

SciTech Connect

The Brookhaven National Laboratory polarized H/sup -/ injection program for the AGS will utilize a Radio Frequency Quadrupole for acceleration between the polarized source and the Alvarez Linac. Although operation will commence with a few ..mu.. amperes of H/sup -/ current, it is anticipated that future polarized H/sup -/ sources will have a considerably improved output. The RFQ will operate at 201.25 MHz and will be capable of handling a beam current of 0.02 amperes with a duty cycle of 0.25%. The resulting low average power has allowed novel solutions to the problems of vane alignment, rf current contacts, and removal of heat from the vanes. The cavity design philosophy will be discussed together with the thermodynamics of heat removal from the vane. Details of the fabrication will be presented with a status report.

McKenzie-Wilson, R.B.

1983-01-01

289

Radio frequency identification (RFID) applied to surgical sponges.  

PubMed

Use of gauze sponges that have been embedded with passive radio frequency identification (RFID) tags presents a high probability of reducing or eliminating instances of gossypiboma, or retained surgical sponge. The use of human counts during surgical operations, especially during instances where unexpected or emergency events occur, can result in errors where surgical instruments, most often gauze sponges, are retained within the patient's body, leading to complications at a later date. Implementation of an automatic inventory record system, for instance, RFID, may greatly reduce these incidences by removing the human factor and would improve patient safety by eliminating the current sponge count protocol. Experiments performed by placing RFID-labeled sponges within an animal and removing them have demonstrated that tags are at least partially readable inside the body cavity and fully readable once removed, suggesting the possibility of an automated sponge count system pending further development of this technology. PMID:17484000

Rogers, A; Jones, E; Oleynikov, D

2007-07-01

290

The high-frequency characteristics of solar radio bursts  

NASA Technical Reports Server (NTRS)

The millimeter, microwave, and soft X-ray emission from a number of solar flares is compared in order to determine the properties of the HF radio emission of flares. The millimeter observations use a sensitive interferometer at 86 GHz which offers much better sensitivity and spatial resolution than most previous high-frequency observations. The 86-GHz emission onset appears often to be delayed with respect to the microwave onset. Even in large flares the millimeter-wavelength emission can arise in sources of only a few arc sec dimension. The millimeter emission in the impulsive phase does not correlate with the soft X-ray emission, and thus is unlikely to contain any significant thermal bremsstrahlung component. The electron energy distributions implied by the millimeter observations are much flatter (spectral indices of 2.5 to 3.6) than is usual for microwave or hard X-ray observations.

Lim, J.; White, S. M.; Kundu, M. R.; Gary, D. E.

1992-01-01

291

Electron beam diagnostics for a superconducting radio frequency photoelectron injector  

SciTech Connect

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 and 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.

Kamps, Thorsten; Boehlick, Daniel; Dirsat, Marc; Lipka, Dirk; Quast, Torsten; Rudolph, Jeniffa; Schenk, Mario [Berliner Elektronenspeicherring-Gesellschaft fuer Synchrotronstrahlung, BESSY Albert-Einstein-Strasse 15, 12489 Berlin (Germany); Arnold, Andre; Staufenbiel, Friedrich; Teichert, Jochen [Forschungszentrum Dresden-Rossendorf, FZD, Bautzner Landstrasse 128, 01328 Dresden (Germany); Klemz, Guido; Will, Ingo [Max-Born-Institut Berlin, MBI, Max-Born-Strasse 2 A, 12489 Berlin (Germany)

2008-09-15

292

Superconducting radio-frequency modules test faciilty operating experience  

SciTech Connect

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.

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

2007-07-01

293

Fiducialization of Superconducting Radio Frequency Cryomodules at Jefferson Lab  

SciTech Connect

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.

C. J. Curtis; J. Dahlberg; W. Oren; J. Preble; K. Tremblay

2006-09-26

294

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

Microsoft Academic Search

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

G. R. Harp

2005-01-01

295

The Radio Frequency Health Node Wireless Sensor System  

NASA Technical Reports Server (NTRS)

The Radio Frequency Health Node (RFHN) wireless sensor system differs from other wireless sensor systems in ways originally intended to enhance utility as an instrumentation system for a spacecraft. The RFHN can also be adapted to use in terrestrial applications in which there are requirements for operational flexibility and integrability into higher-level instrumentation and data acquisition systems. As shown in the figure, the heart of the system is the RFHN, which is a unit that passes commands and data between (1) one or more commercially available wireless sensor units (optionally, also including wired sensor units) and (2) command and data interfaces with a local control computer that may be part of the spacecraft or other engineering system in which the wireless sensor system is installed. In turn, the local control computer can be in radio or wire communication with a remote control computer that may be part of a higher-level system. The remote control computer, acting via the local control computer and the RFHN, cannot only monitor readout data from the sensor units but can also remotely configure (program or reprogram) the RFHN and the sensor units during operation. In a spacecraft application, the RFHN and the sensor units can also be configured more nearly directly, prior to launch, via a serial interface that includes an umbilical cable between the spacecraft and ground support equipment. In either case, the RFHN wireless sensor system has the flexibility to be configured, as required, with different numbers and types of sensors for different applications. The RFHN can be used to effect realtime transfer of data from, and commands to, the wireless sensor units. It can also store data for later retrieval by an external computer. The RFHN communicates with the wireless sensor units via a radio transceiver module. The modular design of the RFHN makes it possible to add radio transceiver modules as needed to accommodate additional sets of wireless sensor units. The RFHN includes a core module that performs generic computer functions, including management of power and input, output, processing, and storage of data. In a typical application, the processing capabilities in the RFHN are utilized to perform preprocessing, trending, and fusion of sensor data. The core module also serves as the unit through which the remote control computer configures the sensor units and the rest of the RFHN.

Valencia, J. Emilio; Stanley, Priscilla C.; Mackey, Paul J.

2009-01-01

296

Wireless Chalcogenide Nanoionic-Based Radio-Frequency Switch  

NASA Technical Reports Server (NTRS)

A new nonvolatile nanoionic switch is powered and controlled through wireless radio-frequency (RF) transmission. A thin layer of chalcogenide glass doped with a metal ion, such as silver, comprises the operational portion of the switch. For the switch to function, an oxidizable electrode is made positive (anode) with respect to an opposing electrode (cathode) when sufficient bias, typically on the order of a few tenths of a volt or more, is applied. This action causes the metal ions to flow toward the cathode through a coordinated hopping mechanism. At the cathode, a reduction reaction occurs to form a metal deposit. This metal deposit creates a conductive path that bridges the gap between electrodes to turn the switch on. Once this conductive path is formed, no further power is required to maintain it. To reverse this process, the metal deposit is made positive with respect to the original oxidizable electrode, causing the dissolution of the metal bridge thereby turning the switch off. Once the metal deposit has been completely dissolved, the process self-terminates. This switching process features the following attributes. It requires very little to change states (i.e., on and off). Furthermore, no power is required to maintain the states; hence, the state of the switch is nonvolatile. Because of these attributes the integration of a rectenna to provide the necessary power and control is unique to this embodiment. A rectenna, or rectifying antenna, generates DC power from an incident RF signal. The low voltages and power required for the nanoionic switch control are easily generated from this system and provide the switch with a novel capability to be operated and powered from an external wireless device. In one realization, an RF signal of a specific frequency can be used to set the switch into an off state, while another frequency can be used to set the switch to an on state. The wireless, miniaturized, and nomoving- part features of this switch make it suitable for applications such as integration into garments, RFID (radio-frequency identification) tags, and conformal structures (e.g., aircraft wings, sounding rockets contours, etc). In the case of RFID tags the innovation will provide countermeasures to attempts for identity theft and other uninvited attempts for retrieval of information. It could also be applicable to the automotive industry as well as the aerospace industry for collision avoidance and phased array radar systems, respectively

Nessel, James; Miranda, Felix

2013-01-01

297

OFDM Physical Layer Implementation for the Kansas University Agile Radio  

E-print Network

OFDM Physical Layer Implementation for the Kansas University Agile Radio Jordan Douglas Guffey ITTC transmitter and receiver and has been implemented in VHDL for use on the Kansas University Agile Radio (KUAR). The KUAR is an experimental software-defined radio platform that is intended for research in frequency-agile

Kansas, University of

298

Benefits of three frequency ionospheric corrections in Radio Occultation soundings  

NASA Astrophysics Data System (ADS)

The Finnish Meteorological Institute (FMI) has assessed the potential benefits from using the third transmission frequency of the next generation GNSS systems in the sounding of the atmosphere with Radio Occultation (RO). This research has been performed in the framework of the Ionospheric Effects in GNSS Radio Occultation Data study funded by EUMETSAT. The objective of this study was to analyze the advantages of three frequency soundings as part of the planning of the future EUMETSAT satellite missions. The research has been performed by simulating the three frequency transmissions of the next generation GPS and GALILEO systems with the EGOPS (End-to-end GNSS Occultation Performance Simulator) software package developed by the international EGOPS consortium. EGOPS allows simulations of RO missions by propagating the orbits of the transmitting and receiving satellites, determining the geodetic locations and geometries of the soundings and ray tracings of the signals propagation paths. In the study we have ensured that all specified conditions are met by simulating over 1700 occultation soundings. The simulations included both the GPS and the future GALILEO constellations and signals. A LEO satellite at the orbit of the EUMETSAT Metop-A has been used to simulate an RO receiver. The global distribution of the occultations ensured that all occultation times and geometries of interest have been covered. Three solar activity levels have been used to simulated solar minimum, normal and solar maximum conditions. Two ionospheric correction techniques taking benefit of the third GNSS frequency have been tested in the study. The first tested method was a three-frequency linear combination technique. This method is an expansion of the two frequency linear combination that is currently widely used in GNSS navigation and in RO data processing. The disadvantage of this approach is that the noise level in the retrieved bending angle profile is significantly increased. The second tested methods is an ionospheric ambiguity removal with a combination of widelane (WL) and extra-widelane (EWL) signals. This method does not increase the noise level as much as the linear combination method, but is computationally slightly more complex and requires combining code phase observations with the carrier phase observations. The results of the simulations and the retrievals have been rigorously analyzed both statistically and by investigating selected individual observations. The results indicate that ionospheric correction with three frequencies can significantly reduce the ionospheric error in the neutral atmosphere sounding in the heights of 35 - 60 km. This can potentially increase the useful height range of RO soundings in operational NWP (Numerical Weather Prediction) and climate monitoring. This result is very important because very few atmospheric sounding techniques can provide global information from the upper stratosphere and lower mesosphere region. This presentation will show the results of the performed study including descriptions of the simulations and the tested ionospheric correction techniques. The bending angle retrieval accuracy benefits will be quantified both statistically and by analysis of selected complex signal propagation cases. Finally, the presentation will also address the potential benefits of three frequency soundings in space weather observations by RO.

Luntama, J.

2008-12-01

299

Enhancement of electromagnetic propagation through complex media for Radio Frequency Identification  

E-print Network

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 ...

Marti, Uttara P

2005-01-01

300

Radio-Frequency Tank Eigenmode Sensor for Propellant Quantity Gauging  

NASA Technical Reports Server (NTRS)

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

Zimmerli, Gregory A.; Buchanan, David A.; Follo, Jeffrey C.; Vaden, Karl R.; Wagner, James D.; Asipauskas, Marius; Herlacher, Michael D.

2010-01-01

301

Frequency allocations for passive use of the radio spectrum to make scientific studies  

NASA Technical Reports Server (NTRS)

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.

Stull, M. A.; Alexander, G.

1976-01-01

302

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

SciTech Connect

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

Kim, Dan Bee [Division of Physical Metrology, Korea Research Institute of Standards and Science, 209 Gajeongno, Yuseong-gu, Daejeon 305-340 (Korea, Republic of); Jung, H.; Gweon, B.; Rhee, J. K.; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Moon, S. Y. [LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea, Republic of)

2011-04-15

303

Latitudinal beaming of Jupiter's low frequency radio emissions  

NASA Technical Reports Server (NTRS)

By comparing RAE-1 and IMP-6 satellite measurements of Jupiter's radio emission near 1MHz with recent Voyager-1 and 2 observations in the same frequency range, the properties of the low frequency radiation pattern over a 10 deg range of latitudes with respect to the Jovian rotation equator can be studied. These observations, which cover a wider latitudinal range than is possible from the earth, are consistent with many aspects of earlier ground-based measurements used to infer a sharp beaming pattern for the decameter wavelength emissions. Marked, systematic changes are found in the statistical occurrence probability distributions with system 3 central meridian longitude as the jovigraphic latitude of the observer changes over this range. Simultaneous observations by the two Voyager spacecraft suggest that the instantaneous beam width may be no more than a few degrees at times. The new hectometer-wave results can be interpreted in terms of a narrow, curved sheet at a fixed magnetic latitude into which the emission is beamed to escape the planet.

Alexander, J. K.; Desch, M. D.; Kaiser, M. L.; Thieman, J. R.

1979-01-01

304

Frequency variations of solar radio zebras and their power-law spectra  

NASA Astrophysics Data System (ADS)

Context. During solar flares several types of radio bursts are observed. The fine striped structures of the type IV solar radio bursts are called zebras. Analyzing them provides important information about the plasma parameters of their radio sources. We present a new analysis of zebras. Aims: Power spectra of the frequency variations of zebras are computed to estimate the spectra of the plasma density variations in radio zebra sources. Methods: Frequency variations of zebra lines and the high-frequency boundary of the whole radio burst were determined with and without the frequency fitting. The computed time dependencies of these variations were analyzed with the Fourier method. Results: First, we computed the variation spectrum of the high-frequency boundary of the whole radio burst, which is composed of several zebra patterns. This power spectrum has a power-law form with a power-law index -1.65. Then, we selected three well-defined zebra-lines in three different zebra patterns and computed the spectra of their frequency variations. The power-law indices in these cases are found to be in the interval between -1.61 and -1.75. Finally, assuming that the zebra-line frequency is generated on the upper-hybrid frequency and that the plasma frequency ?pe is much higher than the electron-cyclotron frequency ?ce, the Fourier power spectra are interpreted to be those of the electron plasma density in zebra radio sources.

Karlický, M.

2014-01-01

305

A high-temperature superconducting receiver for low-frequency radio waves  

Microsoft Academic Search

We have developed a receiver for low-frequency radio waves using high-temperature superconducting quantum interference devices (SQUIDs). The primary application of such a receiver is to communicate in underground areas where the overburden results in significant losses at the usual radio frequencies. The receiver constructed consists of a SQUID, a small dewar, control electronics, and a battery pack. The SQUID was

D. Reagor; Yan Fan; C. Mombourquette; Quanxi Jia; L. Stolarczyk

1997-01-01

306

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

E-print Network

] for a review). The semidiur- nal tide consists of two oppositely traveling Kelvin waves, one incoming fromTidal 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

307

Radio Frequency Heating of Foods: Principles, Applications and Related Properties—A Review  

Microsoft Academic Search

Radio frequency (RF) heating is a promising technology for food applications because of the associated rapid and uniform heat distribution, large penetration depth and lower energy consumption. Radio frequency heating has been successfully applied for drying, baking and thawing of frozen meat and in meat processing. However, its use in continuous pasteurization and sterilization of foods is rather limited. During

Punidadas Piyasena; Chantal Dussault; Tatiana Koutchma; H. S. Ramaswamy; G. B. Awuah

2003-01-01

308

Room temperature femtotesla radio-frequency atomic magnetometer W. Chalupczak,1  

E-print Network

Room temperature femtotesla radio-frequency atomic magnetometer W. Chalupczak,1 R. M. Godun,1 S online 12 June 2012) A radio-frequency tunable atomic magnetometer with a sensitivity of about 1 fT/Hz1/2 in a range of 10­500 kHz is demonstrated. The magnetometer is operated in the orientation configuration

309

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

SciTech Connect

We are reporting experimental results on 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 (SRF) cryomodule (in situ operation). This discharge offers an efficient 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 problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. 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.

Popovic, S; Upadhyay, J.; Mammosser, J.; Nikolic, M; Vuskovic, L

2014-11-07

310

Signal processing approaches to radio frequency interference (RFI) suppression  

NASA Astrophysics Data System (ADS)

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.

Braunstein, Matthew; Ralston, James M.; Sparrow, David A.

1994-06-01

311

Nanoionics-Based Switches for Radio-Frequency Applications  

NASA Technical Reports Server (NTRS)

Nanoionics-based devices have shown promise as alternatives to microelectromechanical systems (MEMS) and semiconductor diode devices for switching radio-frequency (RF) signals in diverse systems. Examples of systems that utilize RF switches include phase shifters for electronically steerable phased-array antennas, multiplexers, cellular telephones and other radio transceivers, and other portable electronic devices. Semiconductor diode switches can operate at low potentials (about 1 to 3 V) and high speeds (switching times of the order of nanoseconds) but are characterized by significant insertion loss, high DC power consumption, low isolation, and generation of third-order harmonics and intermodulation distortion (IMD). MEMS-based switches feature low insertion loss (of the order of 0.2 dB), low DC power consumption (picowatts), high isolation (>30 dB), and low IMD, but contain moving parts, are not highly reliable, and must be operated at high actuation potentials (20 to 60 V) generated and applied by use of complex circuitry. In addition, fabrication of MEMS is complex, involving many processing steps. Nanoionics-based switches offer the superior RF performance and low power consumption of MEMS switches, without need for the high potentials and complex circuitry necessary for operation of MEMS switches. At the same time, nanoionics-based switches offer the high switching speed of semiconductor devices. Also, like semiconductor devices, nanoionics-based switches can be fabricated relatively inexpensively by use of conventional integrated-circuit fabrication techniques. More over, nanoionics-based switches have simple planar structures that can easily be integrated into RF power-distribution circuits.

Nessel, James; Lee, Richard

2010-01-01

312

Radio frequency interference prediction with application to satellite earth station site selection and co-ordination  

NASA Astrophysics Data System (ADS)

Until recent times, all Intelsat satellite earth stations in Australia were located in areas remote from the capital cities that are the major sources of international telecommunications traffic. High operating costs and long terrestrial tails that impeded the introduction of new services generated a need for new sites near urban centers. The main obstacle to the selection of such sites is radio frequency interference from or to the well established terrestrial radio-relay network in shared frequency bands. This paper describes the development of Australian expertise in radio-frequency interference prediction and its successful application to the selection and frequency coordination of sites near Sydney, Melbourne and Perth.

Abbasi, R. O.

313

Phase Noise of the Radio Frequency (RF) Beatnote Generated by a Dual-Frequency VECSEL  

E-print Network

We analyze, both theoretically and experimentally, the phase noise of the radio frequency (RF) beatnote generated by optical mixing of two orthogonally polarized modes in an optically pumped dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise within the frequency range of 10 kHz - 50 MHz are investigated for three different nonlinear coupling strengths between the two lasing modes. In the theoretical model, we consider two different physical mechanisms responsible for the RF phase noise. In the low frequency domain (typically below 500 kHz), the dominant contribution to the RF phase noise is shown to come from the thermal fluctuations of the semicondutor active medium induced by pump intensity fluctuations. However, in the higher frequency domain (typically above 500 kHz), the main source of RF phase noise is shown to be the pump intensity fluctuations which are transfered to the intensity noises of the two lasing modes and then to the phase noise via the large Henry factor of the semiconductor gain medium. For this latter mechanism, the nonlinear coupling strength between the two lasing modes is shown to play an important role in the value of the RF phase noise. All experimental results are shown to be in good agreement with theory.

Syamsundar De; Abdelkrim El Amili; Ihsan Fsaifes; Grégoire Pillet; Ghaya Baili; Fabienne Goldfarb; Mehdi Alouini; Isabelle Sagnes; Fabien Bretenaker

2013-11-13

314

Phase Noise of the Radio Frequency (RF) Beatnote Generated by a Dual-Frequency VECSEL  

E-print Network

We analyze, both theoretically and experimentally, the phase noise of the radio frequency (RF) beatnote generated by optical mixing of two orthogonally polarized modes in an optically pumped dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise within the frequency range of 10 kHz - 50 MHz are investigated for three different nonlinear coupling strengths between the two lasing modes. In the theoretical model, we consider two different physical mechanisms responsible for the RF phase noise. In the low frequency domain (typically below 500 kHz), the dominant contribution to the RF phase noise is shown to come from the thermal fluctuations of the semicondutor active medium induced by pump intensity fluctuations. However, in the higher frequency domain (typically above 500 kHz), the main source of RF phase noise is shown to be the pump intensity fluctuations which are transfered to the intensity noises of the two lasing modes and then to the phase noise...

De, Syamsundar; Fsaifes, Ihsan; Pillet, Grégoire; Baili, Ghaya; Goldfarb, Fabienne; Alouini, Mehdi; Sagnes, Isabelle; Bretenaker, Fabien

2013-01-01

315

Phase Noise of the Radio Frequency (RF) Beatnote Generated by a Dual-Frequency VECSEL  

NASA Astrophysics Data System (ADS)

We analyze, both theoretically and experimentally, the phase noise of the radio frequency (RF) beatnote generated by optical mixing of two orthogonally polarized modes in an optically pumped dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise within the frequency range of 10 kHz - 50 MHz are investigated for three different nonlinear coupling strengths between the two lasing modes. In the theoretical model, we consider two different physical mechanisms responsible for the RF phase noise. In the low frequency domain (typically below 500 kHz), the dominant contribution to the RF phase noise is shown to come from the thermal fluctuations of the semicondutor active medium induced by pump intensity fluctuations. However, in the higher frequency domain (typically above 500 kHz), the main source of RF phase noise is shown to be the pump intensity fluctuations which are transfered to the intensity noises of the two lasing modes and then to the phase noise via the large Henry factor of the semiconductor gain medium. For this latter mechanism, the nonlinear coupling strength between the two lasing modes is shown to play an important role in the value of the RF phase noise. All experimental results are shown to be in good agreement with theory.

De, Syamsundar; El Amili, Abdelkrim; Fsaifes, Ihsan; Pillet, Gregoire; Baili, Ghaya; Goldfarb, Fabienne; Alouini, Mehdi; Sagnes, Isabelle; Bretenaker, Fabien

2014-04-01

316

R.E.P.E.A.T.E.R.S Radio Experts Perplexed Engineering A Thoroughly Efficient Repeater System  

E-print Network

Control #10500 Abstract This paper examines the challenges of amateur radio network planning by exploring and Statement of Problem 1.1 Introduction Radio enthusiasts around the world use amateur radio frequency bands the allowed power usage of amateur radio transmitters and limited equipment size, the broadcast distance range

Morrow, James A.

317

Analog optoelectronic independent component analysis for radio frequency signals  

NASA Astrophysics Data System (ADS)

This thesis addresses the problem of blind source separation of signals at radio frequencies. Independent component analysis (ICA), which includes a second-order decorrelation followed by a fourth-order decorrelation, uses signal independence to estimate the original signals from the received mixtures. Until now, ICA has been applied to many applications at or below audio frequencies. The work presented here demonstrates that an optoelectronic implementation using the parallel processing nature of dynamic holography can overcome the computational difficulties associated with algorithmic implementations of ICA. The holographic nature of a photorefractive crystal combined with the non-linearity of an electro-optic modulator in a feedback loop can be described by a nonlinear dynamical equation. The dynamics can be cast in the form of Lotka-Volterra equations used to study the dynamics of competing populations of species. Although this analogy with the animal world is interesting, the dynamical equation associated with the fourth-order decorrelation system is fascinating. The statistics associated with the original signals, rather than an external potential, determine the dynamics of the system. In particular, the system is multistable, metastable, or monostable depending on whether the probability density functions of the original signals are sub-Gaussian, Gaussian, or super-Gaussian, respectively. The multistable solution, which occurs for sub-Gaussian signals, provides the winner-takes-all behavior required to separate signals. This ability to separate sub-Gaussian signals is advantageous since signals modulated on a sinusoidal carrier are sub-Gaussian. The fourth-order decorrelation system achieves greater than 40 dB signal separation on 200 MHz single-frequency sine waves and greater than 20 dB signal separation for 10 MHz bandwidth signals. The system performance is degraded by 10 to 20 dB when mixed electronically due to imperfections in the mixing circuitry. The development of a broadband electro-optic modulator capable of modulating to, at least, twice the half-wave voltage was instrumental to achieving radio frequency blind source separation. This compact 532 nm Lithium Niobate modulator has a 300 MHz bandwidth and a half-wave voltage of less than 16 V. To our knowledge, this is the only free-space modulator capable of this modulation depth. This thesis also advances the theoretical work in the area of optoelectronic signal processing. Three of the main contributors to signal separation degradation are studied to aid in the characterization and improved performance of the fourth-order decorrelation feedback loop. The fourth-order decorrelation system requires a preprocessor, which orthogonalizes the input signal mixtures. The theoretical framework of an optoelectronic system that performs principal component analysis (PCA), one method of orthogonalizing the signal mixtures, is also presented. The PCA feedback loop looks identical to the fourth-order decorrelation feedback loop, except the electro-optic modulator is used in its linear regime while the photorefractive gain saturates. Because of the physical similarity of the two optoelectronic feedback loops, our hope is that modular designs will aid in the application of this technology to the telecommunications arena.

Baylor, Martha-Elizabeth

318

Radio frequency coil technology for small-animal MRI.  

PubMed

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

Doty, F David; Entzminger, George; Kulkarni, Jatin; Pamarthy, Kranti; Staab, John P

2007-05-01

319

Radio Frequency (RF) Attenuation Measurements of the Space Shuttle Vehicle  

NASA Technical Reports Server (NTRS)

Following the loss of Columbia, the Columbia Accident Investigation Board (CAIB) provided recommendations to be addressed prior to Return To Flight (RTF). As a part of CAIB Recommendation 3.4.1 - Ground Based Imagery, new C-band and X-band radars were added to the array of ground-based radars and cameras already in-situ at Kennedy Space Center. Because of higher power density considerations and new operating frequencies, the team of Subject Matter Experts (SMEs) assembled to investigate the technical details of introducing the new radars recommended a series of radio frequency (RF) attenuation tests be performed on the Space Shuttle vehicle to establish the attenuation of the vehicle outer mold line structure with respect to its external RF environment. Because of time and complex logistical constraints, it was decided to split the test into two separate efforts. The first of these would be accomplished with the assistance of the Air Force Research Laboratory (AFRL), performing RF attenuation measurements on the aft section of OV-103 (Discovery) while in-situ in Orbiter Processing Facility (OPF) 3, located at Kennedy Space Center. The second would be accomplished with the assistance of the National Institute of Standards and Technology (NIST) and the electromagnetic interference (EMI) laboratory out of the Naval Air Warfare Center, Patuxent River, Maryland (PAX River), performing RF attenuation measurements on OV-105 (Endeavour) in-situ inside the Space Shuttle Landing Facility (SLF) hangar, also located at Kennedy Space Center. This paper provides a summary description of these efforts and their results.

Scully, R. C.; Kent, B. M.; Kempf, D. R.; Johnk, R. T.

2006-01-01

320

Radio-frequency spectroscopy of polarons in ultracold Bose gases  

NASA Astrophysics Data System (ADS)

Recent experimental advances enabled the realization of mobile impurities immersed in a Bose-Einstein condensate (BEC) of ultracold atoms. Here, we consider impurities with two or more internal hyperfine states, and study their radio-frequency (rf) absorption spectra, which correspond to transitions between two different hyperfine states. We calculate rf spectra for the case when one of the hyperfine states involved interacts with the BEC, while the other state is noninteracting, by performing a nonperturbative resummation of the probabilities of exciting different numbers of phonon modes. In the presence of interactions, the impurity gets dressed by Bogoliubov excitations of the BEC, and forms a polaron. The rf signal contains a ?-function peak centered at the energy of the polaron measured relative to the bare impurity transition frequency with a weight equal to the amount of bare impurity character in the polaron state. The rf spectrum also has a broad incoherent part arising from the background excitations of the BEC, with a characteristic power-law tail that appears as a consequence of the universal physics of contact interactions. We discuss both the direct rf measurement, in which the impurity is initially in an interacting state, and the inverse rf measurement, in which the impurity is initially in a noninteracting state. In the latter case, in order to calculate the rf spectrum, we solve the problem of polaron formation: a mobile impurity is suddenly introduced in a BEC, and dynamically gets dressed by Bogoliubov phonons. Our solution is based on a time-dependent variational ansatz of coherent states of Bogoliubov phonons, which becomes exact when the impurity is localized. Moreover, we show that such an ansatz compares well with a semiclassical estimate of the propagation amplitude of a mobile impurity in the BEC. Our technique can be extended to cases when both initial and final impurity states are interacting with the BEC.

Shashi, Aditya; Grusdt, Fabian; Abanin, Dmitry A.; Demler, Eugene

2014-05-01

321

Analyzing Radio-Frequency Coverage for the ISS  

NASA Technical Reports Server (NTRS)

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.

Bolen, Steven M.; Sham, Catherine C.

2007-01-01

322

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect

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.

Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

2009-11-11

323

Three-dimensional effects for radio frequency antenna modeling  

NASA Astrophysics Data System (ADS)

Electromagnetic field calculations for radio frequency (rf) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven rf current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

1994-10-01

324

Three-dimensional effects for radio frequency antenna modeling  

NASA Astrophysics Data System (ADS)

Electromagnetic field calculations for radio frequency (RF) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. The 2-D calculations predict that the return currents in the sidewalls of the antenna structure depend strongly on the plasma parameters, but this prediction is suspect because of experimental evidence. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform three-dimensional (3-D) modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap and conducting sidewalls are considered. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven RF current to return in the antenna structure rather than the plasma, as in the 2-D model. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading predicted from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model, even with end-effect corrections for the 2-D model.

Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

325

Radio-frequency plasma transducer for use in harsh environments.  

PubMed

We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer, eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0-5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate. PMID:17979443

May, Andrew; Andarawis, Emad

2007-10-01

326

Optimization framework for a radio frequency gun based injector  

NASA Astrophysics Data System (ADS)

Linear accelerator based light sources are used to produce coherent x-ray beams with unprecedented peak intensity. In these devices, the key parameters of the photon beam such as brilliance and coherence are directly dependent on the electron beam parameters. This leads to stringent beam quality requirements for the electron beam source. Radio frequency (RF) guns are used in such light sources since they accelerate electrons to relativistic energies over a very short distance, thus minimizing the beam quality degradation due to space charge effects within the particle bunch. Designing such sources including optimization of its beam parameters is a complex process where one needs to meet many requirements simultaneously. It is useful to have a tool to automate the design optimization in the context of the injector beam dynamics performance. Evolutionary and genetic algorithms are powerful tools to apply to nonlinear multi-objective optimization problems, and they have been successfully used in injector optimizations where the electric field profiles for the accelerating devices are fixed. Here the genetic algorithm based approach is extended to modify and optimize the electric field profile for an RF gun concurrently with the injector performance. Two field modification methods are used. This dissertation presents an overview of the optimization system and examples of its application to a state of the art RF gun. Results indicate improved injector performance is possible with unbalanced electric field profiles where the peak field in the cathode cell is larger than in subsequent cells.

Hofler, Alicia S.

327

Method of making radio frequency ion source antenna  

DOEpatents

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.

Ehlers, Kenneth W. (Alamo, CA); Leung, Ka-Ngo (Hercules, CA)

1988-01-01

328

An application of uncertain numbers in radio frequency power measurement  

NASA Astrophysics Data System (ADS)

The uncertain-numbers method (Hall B D 2006 Metrologia 43 L56-61) is an alternative computational procedure to the Law of Propagation of Uncertainty (LPU) described in the Guide to the Expression of Uncertainty in Measurement. One advantage of the method is that data processing can be carried out in an arbitrary series of steps and much of the mathematical analysis normally associated with the LPU can be automated by software. This has applications for measuring systems, which are modular in design and use internal data processing to apply corrections to raw data. Several scenarios involving radio frequency power measurements are used to illustrate the new method in this context. The scenarios show something of the difficulty inherent in calculating uncertainty for modern measurement systems and in particular highlight the occurrence of systematic errors arising from internal instrument correction factors. Such errors introduce correlation to a series of measurements and must be handled with care when functions of results, such as means, differences and ratios, are required.

Hall, B. D.

2009-06-01

329

Radio-frequency energy quantification in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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.

Alon, Leeor

330

Radio frequency leakage current from unipolar laparoscopic electrocoagulators.  

PubMed

Radio frequency (RF) leakage current has been suspected of causing accidental tissue burns associated with laparoscopic electrocoagulation used for tubal sterilization. A study was done to determine the levels of capacitively coupled RF leakage current from six unipolar laparoscopes manufactured by five companies. Leakage current values ranging from less than 100 mA to over 550 mA were measured at electrosurgical unit power settings of up to 150 w into 1,000 ohms. These levels represent 24-62% of the total electrosurgical current generated by the electrosurgical units. Using a criterion for tissue injury of 100 mA/sq cm applied for ten seconds, leakage current levels exceeding 400 mA are capable of producing burns either at the abdominal wall or to internal organs that accidentally come into contact with the body of the laparoscope. One of the six devices tested had leakage current levels higher than 400 mA at power settings lower than 100 w. Capacitance measurements between the unipolar laparoscope body and the forceps ranged from 53 to 140 picofarads. PMID:6226780

DiNovo, J A

1983-09-01

331

Image transmission in tactical radio frequency shared network propagation environments  

NASA Astrophysics Data System (ADS)

The need to transmit images across tactical radio frequency (rf) links has been identified in army digitization applications. For example, military doctrine requires that tactical functions like identification of battlefield entities as potential targets and battle damage assessment be performed by the soldier. Currently, a key input to these processes is imagery. Therefore, the quality and timeliness of the image directly impact tactical performance. The military is investigating the employment of remote sensors and advanced communications systems to meet this requirement as part of its digitization effort. Army communications systems exist that partially meet this requirement. However, many existing solutions employ these legacy systems in the context of a point-to-point communications architecture. Solutions to the problem of transmitting images across a rf network have not been fully explored. The term network implies that the rf transmission media is common to and shared by multiple subscribers. It is a suite of capabilities that collectively manage media access and information transfer for its subscribers thus providing substantial improvements in effectiveness, efficiency, and robustness. This paper discusses the challenges of transmitting images using one army legacy communications system in a tactical rf network, presents a conceptual framework for attacking the problem, and discusses one solution.

White, Kent H.; Wagner, Kerry A.; O'Hanian, Scott

1997-06-01

332

Monitoring of tumor radio frequency ablation using derivative spectroscopy  

NASA Astrophysics Data System (ADS)

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.

Spliethoff, Jarich W.; Tanis, Erik; Evers, Daniel J.; Hendriks, Benno H. W.; Prevoo, Warner; Ruers, Theo J. M.

2014-09-01

333

Modified transmitter attachment method for adult ducks  

USGS Publications Warehouse

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.

Pietz, P.J.; Brandt, D.A.; Krapu, G.L.; Buhl, D.A.

1995-01-01

334

Investigation on the Frequency Allocation for Radio Astronomy at the L Band  

NASA Astrophysics Data System (ADS)

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.

Abidin, Z. Z.; Umar, R.; Ibrahim, Z. A.; Rosli, Z.; Asanok, K.; Gasiprong, N.

2013-09-01

335

Assessment of radio frequency exposures in schools, homes, and public places in Belgium.  

PubMed

Characterization of exposure from emerging radio frequency (RF) technologies in areas where children are present is important. Exposure to RF electromagnetic fields (EMF) was assessed in three "sensitive" microenvironments; namely, schools, homes, and public places located in urban environments and compared to exposure in offices. In situ assessment was conducted by performing spatial broadband and accurate narrowband measurements, providing 6-min averaged electric-field strengths. A distinction between internal (transmitters that are located indoors) and external (outdoor sources from broadcasting and telecommunication) sources was made. Ninety-four percent of the broadband measurements were below 1 V m(-1). The average and maximal total electric-field values in schools, homes, and public places were 0.2 and 3.2 V m(-1) (WiFi), 0.1 and 1.1 V m(-1) (telecommunication), and 0.6 and 2.4 V m(-1) (telecommunication), respectively, while for offices, average and maximal exposure were 0.9 and 3.3 V m(-1) (telecommunication), satisfying the ICNIRP reference levels. In the schools considered, the highest maximal and average field values were due to internal signals (WiFi). In the homes, public places, and offices considered, the highest maximal and average field values originated from telecommunication signals. Lowest exposures were obtained in homes. Internal sources contributed on average more indoors (31.2%) than outdoors (2.3%), while the average contributions of external sources (broadcast and telecommunication sources) were higher outdoors (97.7%) than at indoor positions (68.8%). FM, GSM, and UMTS dominate the total downlink exposure in the outdoor measurements. In indoor measurements, FM, GSM, and WiFi dominate the total exposure. The average contribution of the emerging technology LTE was only 0.6%. PMID:25353235

Verloock, Leen; Joseph, Wout; Goeminne, Francis; Martens, Luc; Verlaek, Mart; Constandt, Kim

2014-12-01

336

Delayed bronchobiliary fistula and cholangiolithiasis following percutaneous radio frequency ablation for hepatocellular carcinoma.  

PubMed

Although percutaneous radio frequency ablation for hepatocellular carcinoma is a minimally invasive therapy, there are some complications reported; major complications include hemorrhage (0.477%), hepatic injuries (1.690%), and extrahepatic organ injuries (0.691%). We, for the first time, described a rare complication of delayed bronchobiliary fistula and cholangiolithiasis in common bile duct following radio frequency ablation and the salvage treatment in a patient with chronic hepatitis B virus infection. Surgeons should be aware of severe and rare complications before deciding the ablation area and when performing radio frequency ablation, and should be aware of the relevant salvage treatment. PMID:25135987

Zhong, Yuesi; Deng, Meihai; Li, Kai; Xu, Ruiyun

2015-02-01

337

47 CFR 80.909 - Radiotelephone transmitter.  

Code of Federal Regulations, 2011 CFR

...Boats § 80.909 Radiotelephone transmitter. (a) The medium frequency transmitter must have a peak envelope output...antenna consisting of a series network of 10 ohms effective resistance and 200 picofarads capacitance or an artificial antenna...

2011-10-01

338

Energy Saving Glass Lamination via Selective Radio-Frequency Heating  

SciTech Connect

This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for potential RF lamination users. A path to industrial energy benefits and revenue through industrial equipment sales was established in a partnership with Thermex Thermatron, a manufacturer of RF equipment.

Shulman, Holly S.; Allan, Shawn M.

2009-11-11

339

H- radio frequency source development at the Spallation Neutron Source.  

PubMed

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. PMID:22380234

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

340

H- radio frequency source development at the Spallation Neutron Source  

SciTech Connect

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}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, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}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 {approx}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 {approx}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.

Welton, Robert F [ORNL; Pennisi, Terry R [ORNL; Roseberry, Ron T [ORNL; Stockli, Martin P [ORNL

2012-01-01

341

Three-dimensional effects for radio frequency antenna modeling  

NASA Astrophysics Data System (ADS)

Electromagnetic field calculations for radio frequency (RF) antennas in two dimensions (2-D) neglect finite antenna length effects as well as the feeders leading to the main current strap. Comparisons with experiments indicate that these 2-D calculations can overestimate the loading of the antenna and fail to give the correct reactive behavior. To study the validity of the 2-D approximation, the Multiple Antenna Implementation System (MAntIS) has been used to perform 3-D modeling of the power spectrum, plasma loading, and inductance for a relevant loop antenna design. Effects on antenna performance caused by feeders to the main current strap, conducting sidewalls, and finite phase velocity are considered. The plasma impedance matrix for the loading calculation is generated by use of the ORION-1D code. The 3-D model is benchmarked with the 2-D model in the 2-D limit. For finite-length antennas, inductance calculations are found to be in much more reasonable agreement with experiments for 3-D modeling than for the 2-D estimates. The modeling shows that the feeders affect the launched power spectrum in an indirect way by forcing the driven RF current to return in the antenna sidewalls rather than in the plasma as in the 2-D model. Thus, the feeders have much more influence than the plasma on the currents that return in the sidewall. It has also been found that poloidal dependencies in the plasma impedance matrix can reduce the loading from that predicted in the 2-D model. For some plasma parameters, the combined 3-D effects can lead to a reduction in the predicted loading by as much as a factor of 2 from that given by the 2-D model.

Carter, M. D.; Batchelor, D. B.; Stallings, D. C.

1993-09-01

342

H- radio frequency source development at the Spallation Neutron Sourcea)  

NASA Astrophysics Data System (ADS)

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.

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

343

Radio-Frequency Plasma Cleaning of a Penning Malmberg Trap  

NASA Technical Reports Server (NTRS)

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.

Sims, William Herbert, III; Martin, James; Pearson, J. Boise; Lewis, Raymond

2005-01-01

344

Radio Frequency Characteristics of Printed Meander Inductors and Interdigital Capacitors  

NASA Astrophysics Data System (ADS)

Radio frequency (RF) characterizations of printed silver ink inductors manufactured at low (150 °C) and high (850 °C) temperatures and interdigital capacitors manufactured at high (850 °C) temperatures were carried out in the 500 MHz to 6 GHz range. The S-parameter responses of the components were measured with a probe station and an Agilent 8510C network analyzer. Electrical parameters such as inductance, capacitance, and a quality factor were estimated from experimental results and numerical calculation. Component parameters are dependent on physical dimensions and material properties. The components were created in a 4 ×4 mm2 area with line widths/gaps of 500/500, 250/250, and 200/200 µm. Windings in the coils varied from 2 to 5 turns and finger counts in the capacitors, from 5 to 11 within the defined area and line widths. As a result, low-T-cured (150 °C) silver ink meander line inductors achieved 8 to 18 nH inductances at 1 and 2 GHz with a quality value of 10-25. High-T-cured (850 °C) silver ink meander line inductors had 6-15 nH inductances and quality values were around 100, indicating a conductivity challenge with low-T-cured inks. Interdigital capacitors with 1 to 4 pF capacitances and sufficient quality values were created. A low-loss BaTiO3 coating was printed over the interdigital capacitors; they exhibited suitable electrical characteristics to allow decreasing the physical size of the component.

Myllymaki, Sami; Teirikangas, Merja; Nelo, Mikko; Tulppo, Joel; Soboci?ski, Maciej; Juuti, Jari; Jantunen, Heli; Sloma, Marcin; Jakubowska, Malgorzata

2013-05-01

345

Development of a superconducting radio frequency photoelectron injector  

NASA Astrophysics Data System (ADS)

A superconducting radio frequency (RF) photoelectron injector (SRF gun) is under development at the Research Center Dresden-Rossendorf. This project aims mainly at replacing the present thermionic gun of the superconducting electron linac ELBE. Thereby the beam quality is greatly improved. Especially, the normalized transverse emittance can be reduced by up to one order of magnitude depending on the operating conditions. The length of the electron bunches will be shortened by about two orders of magnitude making the present bunchers in the injection beam line dispensable. The maximum obtainable bunch charge of the present thermionic gun amounts to 80 pC. The SRF gun is designed to deliver also higher bunch charge values up to 2.5 nC. Therefore, this gun can be used also for advanced facilities such as energy recovery linacs (ERLs) and soft X-ray FELs. The SRF gun is designed as a 3{1}/{2} cell cavity structure with three cells basically TESLA cells supplemented by a newly developed gun cell and a choke filter. The exit energy is projected to be 9.5 MeV. In this paper, we present a description of the design of the SRF gun with special emphasis on the physical and technical problems arising from the necessity of integrating a photocathode into the superconducting cavity structure. Preparation, transfer, cooling and alignment of the photocathode are discussed. In designing the SRF gun cryostat for most components wherever possible the technical solutions were adapted from the ELBE cryostat in some cases with major modifications. As concerns the status of the project the design is finished, most parts are manufactured and the gun is being assembled. Some of the key components are tested in special test arrangements such as cavity warm tuning, cathode cooling, the mechanical behavior of the tuners and the effectiveness of the magnetic screening of the cavity.

Arnold, A.; Büttig, H.; Janssen, D.; Kamps, T.; Klemz, G.; Lehmann, W. D.; Lehnert, U.; Lipka, D.; Marhauser, F.; Michel, P.; Möller, K.; Murcek, P.; Schneider, Ch.; Schurig, R.; Staufenbiel, F.; Stephan, J.; Teichert, J.; Volkov, V.; Will, I.; Xiang, R.

2007-07-01

346

High Power RF Transmitters for ICRF Applications on EAST  

NASA Astrophysics Data System (ADS)

An Ion Cyclotron Range of Frequency (ICRF) system with a radio frequency (RF) power of 4 × 1.5 MW was developed for the Experimental Advanced Superconducting Tokamak (EAST). High RF power transmitters were designed as a part of the research and development (R&D) for an ICRF system with long pulse operation at megawatt levels in a frequency range of 25 MHz to 70 MHz. Studies presented in this paper cover the following parts of the high power transmitter: the three staged high power amplifier, which is composed of a 5 kW wideband solid state amplifier, a 100 kW tetrode drive stage amplifier and a 1.5 MW tetrode final stage amplifier, and the DC high voltage power supply (HVPS). Based on engineering design and static examinations, the RF transmitters were tested using a matched dummy load where an RF output power of 1.5 MW was achieved. The transmitters provide 6 MW RF power in primary phase and will reach a level up to 12 MW after a later upgrade. The transmitters performed successfully in stable operations in EAST and HT-7 devices. Up to 1.8 MW of RF power was injected into plasmas in EAST ICRF heating experiments during the 2010 autumn campaign and plasma performance was greatly improved.

Mao, Yuzhou; Yuan, Shuai; Zhao, Yanping; Zhang, Xinjun; Chen, Gen; Kumazawa, R.; Cheng, Yan; Wang, Lei; Ju, Songqing; Deng, Xu; Qin, Chengming; Yang, Lei

2013-03-01

347

Analytical model for the radio-frequency sheath.  

PubMed

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

Czarnetzki, Uwe

2013-12-01

348

Ion species mix and ion density measurements using radio frequency waves  

Microsoft Academic Search

Radio frequency wave applications have demonstrated great versatility in tokamak plasmas. Two applications, using the same diagnostic design, can make use of a fast Alfven wave to make ion species mix and ion density measurements. A discussion and derivation, using the cold plasma approximation, is given for a fast Alfven radio wave used for making an interferometry density measurement, a

George Wilder Watson III

2003-01-01

349

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

E-print Network

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. Specifically, the technique must be sufficiently agile to enable unlicensed users the ability to transmit

Kansas, University of

350

Spectral occupancy at VHF: implications for frequency-agile cognitive radios  

Microsoft Academic Search

Frequency-agile cognitive radio is a potential solu- tion to the problem of inefficient use of radio spectrum in the 30- 300 MHz (VHF) range. This is especially attractive if networks based on this technology can operate in spectrum left unused by existing users, as opposed to being allocated new spectrum through refarming. This paper presents a preliminary survey of this

Steven W. Ellingson

2005-01-01

351

Calculus, Radio Dials and the Straight-Line Frequency Variable Capacitor  

ERIC Educational Resources Information Center

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.)

Boyadzhiev, Khristo N.

2010-01-01

352

Potential radio frequency interference with the GPS L5 band for radio occultation measurements  

NASA Astrophysics Data System (ADS)

Future radio occultation (RO) receivers are planned to utilize the newly implemented Global Positioning System (GPS) L5 band centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance measuring equipment (DME) and tactical air navigation (TACAN) stations share the same frequency band as GPS L5. The signals from these stations have been identified as possible sources of interference for any GPS L5 receiver, including those used in RO applications. This study utilizes Systems Tools Kit (STK) simulations to gain insight into the power received by a RO satellite in low Earth orbit (LEO) from a DME-TACAN transmission as well as the amount of interfering stations. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME-TACAN station as well as a tool to detail the number of interfering DME-TACAN stations witnessed by a space-based RO receiver over time. The results indicated a large number of DME-TACAN stations transmitting at similar orientations as a receiving RO satellite, thereby leading to the possibility of signal degradation in an unclear interference environment.

Wolff, A. M.; Akos, D. M.; Lo, S.

2014-11-01

353

Integrating Radio Frequency Identification (RFID) data with Electronic Data Interchange (EDI) business processes  

E-print Network

Radio Frequency Identification (RFID) technology, an important component in the enterprise IT infrastructure, must be integrated into the legacy IT system. This thesis studies how RFID technology can be integrated into the ...

Chen, Yan (Yan Henry), 1976-

2005-01-01

354

Observation of parametric instabilities in lower hybrid radio frequency heating of Tokamaks  

Microsoft Academic Search

During lower hybrid radio frequency heating of the Princeton ATC Tokamak, parametric instabilities are exited, and the ion heating correlates with the presence of the parametric spectra. A theoretical interpretation of the parametric instabilities is presented.

M. Porkolab; S. Bernabei; W. M. Hooke; R. W. Motley; T. Nagashima

1976-01-01

355

Portable radio frequency hyperthermia instrumentation. [For heating tumor tissues in situ  

SciTech Connect

Portable radio frequency hyperthermia instrumentation has been constructed for application in the localized heating of human and animal tumors. Tissue temperature is regulated by electronic feedback techniques. Audible and visual monitoring of tissue temperature is provided.

Doss, J.D.; McCabe, C.W.

1980-01-01

356

REGENERATION AND REACTIVATION OF CARBON ADSORBENTS BY RADIO FREQUENCY INDUCTION HEATING  

EPA Science Inventory

1. Electrical Properties of Adsorbents: We measured the electric permittivity of four commercially available carbon adsorbents (supplied by Wesvaco Inc) over the radio frequency range (1 to 40 MHz). Westvaco is by far the largest volume supplier of activated carbon...

357

Impedance matching and DC-DC converter designs for tunable radio frequency based mobile telecommunication systems   

E-print Network

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 ...

Wong, Yan Chiew

2014-06-30

358

Encoding, application and association of radio frequency identification tags on high speed manufacturing lines  

E-print Network

One of the entry points of radio frequency identification technology in supply chain applications is at the manufacturing line, after production, as packaged goods leave for the next link of the network of suppliers, ...

Fonseca, Herbert Moreti, 1973-

2004-01-01

359

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

Code of Federal Regulations, 2011 CFR

...scientific or medical users (but...radio frequency device that is in the...developmental, design or pre-production...capability of the device, provided the device is operated...scientific, or medical user's site...development, design or...

2011-10-01

360

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

Code of Federal Regulations, 2012 CFR

...scientific or medical users (but...radio frequency device that is in the...developmental, design or pre-production...capability of the device, provided the device is operated...scientific, or medical user's site...development, design or...

2012-10-01

361

Abstract--Radio Frequency Identification (RFID) technology mandates by large retailers and various government  

E-print Network

Abstract-- Radio Frequency Identification (RFID) technology mandates by large retailers and various government agencies has driven compliance requirements for many organizations to implement the technology status, adoption drivers, potential benefits, supply chain activities, applicable tasks, and challenges

Mullen, Tracy

362

POTENTIAL HUMAN STUDY POPULATIONS FOR NON-IONIZING (RADIO FREQUENCY) RADIATION HEALTH EFFECTS  

EPA Science Inventory

This research project was initiated to identify potential human populations for future epidemiological studies of the health effects of radio frequency radiation. Through a literature search and contacts with various groups and organizations, numerous occupations and applications...

363

Visible and Controllable RFID Tags Radio frequency identification (RFID) tags containing  

E-print Network

Visible and Controllable RFID Tags Abstract Radio frequency identification (RFID) tags containing associated with RFID, likely because the technology remains largely invisible and uncontrollable alternative tag designs to make RFID visible and controllable. This video and demonstration illustrates

Greenberg, Saul

364

A Radio Frequency Identification (RFID) evaluation strategy for customer fulfillment centers  

E-print Network

Radio Frequency Identification (RFID) is a wireless technology that can be used to track inventory labeled with microchip-embedded identifiers communicating passively with scanners without operator involvement. This ...

Shen, Howard H. (Howard Hao)

2006-01-01

365

Extending the ICRF to Higher Radio Frequencies: 24 and 43 GHz Astrometry  

NASA Technical Reports Server (NTRS)

We present imaging results and source structure analysis of extragalactic radio sources observed using the Very Long Baseline Array (VLBA) at 24 GHz and 43 GHz as part of an ongoing NASA, USNO, NRAO and Bordeaux Observatory collaboration to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies. The K/Q-band image database now includes images of 108 sources at 43 GHz (Q-band) and images of 230 sources at 24 GHz (K-band). Preliminary analysis of the observations taken to date shows that the sources are generally more compact as one goes from the ICRF frequency of 8.4 GHz to 24 GHz. This result is consistent with the standard theory of compact extragalactic radio sources and suggests that reference frames defined at these higher radio frequencies will be less susceptible to the effects of intrinsic source structure than those defined at lower frequencies.

Jacobs, Christopher S.; Charlot, Patrick; Fomalont, Ed B.; Gordon, David; Lanyi, Gabor E.; Ma, Chopo; Naudet, Charles J.; Sovers, Ojars J.; Zhang, Li-Wei D.

2004-01-01

366

Computer simulation of a novel technique for Radio-Frequency Ablation of ventricular arrhythmias  

E-print Network

Ventricular Tachycardia (VT) is a rapid arrhythmia, most commonly due to reentrant electrical activity in the heart. A common treatment for VT is Radio-Frequency Ablation (RFA), which is minimally invasive, but requires ...

Rosbury, Tamara S

2006-01-01

367

A systems approach to the evaluation of Radio Frequency Identification (RFID) in the defense industry  

E-print Network

Radio Frequency Identification (RFID) is a wireless technology with possible applications in the supply chain. RFID tags' fast read rates, non-line-of-sight identification and large storage capacity may revolutionize supply ...

Shah, Ronak R

2005-01-01

368

Extending the ICRF to Higher Radio Frequencies: Imaging and Source Structure  

NASA Technical Reports Server (NTRS)

We present imaging results and source structure analysis of extragalactic radio sources observed using the Very Long Baseline Array (VLBA) at 24 GHz and 43 GHz as part of an ongoing NASA, USNO, NRAO and Bordeaux Observatory collaboration to extend the International Celestial Reference Frame (ICRF) to higher radio frequencies. The K/Q-band image database now includes images of 108 sources at 43 GHz (Q-braid) and images of 230 sources at 24 GHz (K-band). Preliminary analysis of the observations taken to date shows that the sources are generally more compact as one goes from the ICRF frequency of 8.4 GHz to 24 GHz. This result is consistent with the standard theory of compact extragalactic radio sources and suggests that reference frames defined at these higher radio frequencies will be less susceptible to the effects of intrinsic source structure than those defined at lower frequencies.

Boboltz, David A.; Fey, Alan L.; Charlot, Patrick; Fomalont, Edward B.; Lanyi, Gabor E.; Zhang, Li-Wei

2004-01-01

369

Base-level management of radio-frequency radiation-protection program. Final report  

SciTech Connect

AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation-protection program. This report supersedes USAFOEHL Report 80-42, 'A Practical R-F Guide for BEES.'

Rademacher, S.E.; Montgomery, N.D.

1989-04-01

370

Base-level management of radio-frequency radiation-protection program. Final report  

SciTech Connect

AFOEHL developed this report to assist the base-level aerospace medical team manage their radio-frequency radiation protection program. This report supersedes USAFOEHL Report 80-42, 'A practical R-F Guide for BEES.'

Rademacher, S.E.; Montgomery, N.D.

1989-04-01

371

IS THE OBSERVED HIGH-FREQUENCY RADIO LUMINOSITY DISTRIBUTION OF QSOs BIMODAL?  

SciTech Connect

The distribution of QSO radio luminosities has long been debated in the literature. Some argue that it is a bimodal distribution, implying that there are two separate QSO populations (normally referred to as 'radio-loud' and 'radio-quiet'), while others claim it forms a more continuous distribution characteristic of a single population. We use deep observations at 20 GHz to investigate whether the distribution is bimodal at high radio frequencies. Carrying out this study at high radio frequencies has an advantage over previous studies as the radio emission comes predominantly from the core of the active galactic nucleus, and hence probes the most recent activity. Studies carried out at lower frequencies are dominated by the large-scale lobes where the emission is built up over longer timescales (10{sup 7}-10{sup 8} yr), thereby confusing the sample. Our sample comprises 874 X-ray-selected QSOs that were observed as part of the 6dF Galaxy Survey. Of these, 40% were detected down to a 3{sigma} detection limit of 0.2-0.5 mJy. No evidence of bimodality is seen in either the 20 GHz luminosity distribution or in the distribution of the R{sub 20} parameter: the ratio of the radio to optical luminosities traditionally used to classify objects as being either radio-loud or radio-quiet. Previous results have claimed that at low radio luminosities, star formation processes can dominate the radio emission observed in QSOs. We attempt to investigate these claims by stacking the undetected sources at 20 GHz and discuss the limitations in carrying out this analysis. However, if the radio emission was solely due to star formation processes, we calculate that this corresponds to star formation rates ranging from {approx}10 M{sub Sun} yr{sup -1} to {approx}2300 M{sub Sun} yr{sup -1}.

Mahony, Elizabeth K.; Sadler, Elaine M.; Croom, Scott M.; Murphy, Tara [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Ekers, Ronald D.; Feain, Ilana J., E-mail: emahony@physics.usyd.edu.au [Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710 (Australia)

2012-07-20

372

FORTE observations of lightning radio-frequency signatures: Capabilities and basic results  

Microsoft Academic Search

The FORTE satellite, launched on August 29, 1997, carries both radio-frequency-receiver and optical (imaging and photometric) payloads for the study of lightning. The radio-frequency (RF) data for the first 7 months of operation are described, both to illustrate the satellite{close_quote}s capabilities and to explain the basic statistical findings so far. FORTE{close_quote}s multichannel RF trigger system represents a significant advance in

Abram R. Jacobson; Stephen O. Knox; Robert Franz; Donald C. Enemark

1999-01-01

373

Investigation of inherent radio frequency oscillation and minor switching in amorphous chalcogenide semiconductors  

E-print Network

INVESTIGATION OF INHERENT RADIO FREQUENCY OSCILLATION AND MINOR SWITCHING IN AMORPHOUS CHALCOGENIDE SEMICONDUCTORS A Thesis by ROBERT WAYNE GILL JR. Submitted to the Graduate College of Texas AAM University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1971 Major Subject: Electrical Engineering INVESTIGATION OF INHERENT RADIO FREQUENCY OSCILLATION AND MINOR SWITCHING IN AMORPHOUS CHALCOGENIDE SEMICONDUCTORS A Thesis by ROBERT WAYNE GILL JR...

Gill, Robert Wayne

1971-01-01

374

Influence of radio frequency power on structure and ionic conductivity of LiPON thin films  

Microsoft Academic Search

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by radio frequency magnetron sputtering\\u000a of a Li3PO4 target in ambient nitrogen atmosphere. The influence of radio frequency (rf) power on the structure and the ionic conductivity\\u000a of LiPON thin films has been investigated. The morphology, composition, structure and ionic conductivity of thin films were\\u000a characterized by scanning electron

Zongqian Hu; Dezhan Li; Kai Xie

2008-01-01

375

Radio Frequency (RF) Trap for Confinement of Antimatter Plasmas Using Rotating Wall Electric Fields  

NASA Technical Reports Server (NTRS)

Perturbations associated with a rotating wall electric field enable the confinement of ions for periods approaching weeks. This steady state confinement is a result of a radio frequency manipulation of the ions. Using state-of-the-art techniques it is shown that radio frequency energy can produce useable manipulation of the ion cloud (matter or antimatter) for use in containment experiments. The current research focuses on the improvement of confinement systems capable of containing and transporting antimatter.

Sims, William Herbert, III; Pearson, J. Boise

2004-01-01

376

High-frequency radio-wave ablation of osteoid osteoma in the lumbar spine  

Microsoft Academic Search

The authors report on the first known application in the spine of percutaneous ablation of osteoid osteoma using radio-frequency\\u000a waves. The technique involves a CT-guided biopsy of the lesion followed by introduction of a 1-mm probe connected to a radio-frequency\\u000a lesion generator. The procedure was performed on an outpatient basis and the patient experienced immediate relief of his symptoms.\\u000a No

O. L. Osti; R. Sebben

1998-01-01

377

Radio frequency sensing measurements and methods for location classification in wireless networks  

NASA Astrophysics Data System (ADS)

The wireless radio channel is typically thought of as a means to move information from transmitter to receiver, but the radio channel can also be used to detect changes in the environment of the radio link. This dissertation is focused on the measurements we can make at the physical layer of wireless networks, and how we can use those measurements to obtain information about the locations of transceivers and people. The first contribution of this work is the development and testing of an open source, 802.11b sounder and receiver, which is capable of decoding packets and using them to estimate the channel impulse response (CIR) of a radio link at a fraction of the cost of traditional channel sounders. This receiver improves on previous implementations by performing optimized matched filtering on the field-programmable gate array (FPGA) of the Universal Software Radio Peripheral (USRP), allowing it to operate at full bandwidth. The second contribution of this work is an extensive experimental evaluation of a technology called location distinction, i.e., the ability to identify changes in radio transceiver position, via CIR measurements. Previous location distinction work has focused on single-input single-output (SISO) radio links. We extend this work to the context of multiple-input multiple-output (MIMO) radio links, and study system design trade-offs which affect the performance of MIMO location distinction. The third contribution of this work introduces the "exploiting radio windows" (ERW) attack, in which an attacker outside of a building surreptitiously uses the transmissions of an otherwise secure wireless network inside of the building to infer location information about people inside the building. This is possible because of the relative transparency of external walls to radio transmissions. The final contribution of this dissertation is a feasibility study for building a rapidly deployable radio tomographic (RTI) imaging system for special operations forces (SOF). We show that it is possible to obtain valuable tracking information using as few as 10 radios over a single floor of a typical suburban home, even without precise radio location measurements.

Maas, Dustin C.

378

Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.  

PubMed

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA. PMID:19257596

Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

2009-02-13

379

Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere  

SciTech Connect

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Norin, L.; Leyser, T. B.; Nordblad, E.; Thide, B.; McCarrick, M. [Swedish Institute of Space Physics, Uppsala (Sweden); BAE Systems Advanced Technologies, Washington, D.C. (United States)

2009-02-13

380

Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators  

SciTech Connect

The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC. Simulations studies and measurements were conducted that clearly show the correlation between RF noise and longitudinal bunch emittance, identify the major LLRF noise contributions, and determine the RF component dominating this effect. With these results, LHC upgrades and alternative algorithms are evaluated to reduce longitudinal emittance growth during operations. The applications of this work are described with regard to future machines and analysis of new technical implementations, as well as to possible future work which would continue the directions of this dissertation.

Mastoridis, Themistoklis; /Stanford U., Elect. Eng. Dept. /SLAC

2011-03-01

381

Faraday accelerator with radio-frequency assisted discharge (FARAD)  

NASA Astrophysics Data System (ADS)

A new electrodeless accelerator concept, called Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD), that relies on an RF-assisted discharge to produce a plasma, an applied magnetic field to guide the plasma into the acceleration region, and an induced current sheet to accelerate the plasma, is presented. The presence of a preionized plasma allows for current sheet formation at lower discharge voltages and energies than those found in other pulsed inductive accelerator concepts. A proof-of-concept experiment, supported by optical and probe diagnostics, was constructed and used to demonstrate the main features of the FARAD and to gain physical insight into the low-voltage, low-energy current sheet formation and acceleration processes. Magnetic field data indicate that the peak sheet velocity in this unoptimized configuration operating at a pulse energy of 78.5 J is 12 km/s. It is found that changes in the background gas pressure and applied field affect the initial preionized plasma distribution which, in turn, affects the sheet's initial location, relative magnetic impermeability and subsequent velocity history. The results of the experimental investigation motivated further theoretical and numerical investigations of pulsed inductive plasma acceleration. A model consisting of a set of coupled circuit equations and a one-dimensional momentum equation was nondimensionalized leading to the identification of several scaling parameters. Numerical analysis revealed the benefits of underdamped current waveforms and led to an efficiency maximization criterion that requires matching the external circuit's natural period to the acceleration timescale. Predictions of the model were compared to experimental measurements and were found to be in good qualitative agreement and reasonable quantitative agreement for most quantities. A set of design rules aimed at producing a high-performance FARAD thruster are derived using the modeling results and physical insights. The rules concern the optimization of each of the major processes in FARAD: plasma acceleration, current sheet formation, applied field generation, and mass injection and preionization, and are cast as specific prescriptions for the dynamic impedance, inductance change, circuit damping, plasma collisionality (or magnetization), magnetic field strength and topology, and intra-pulse sequencing.

Polzin, Kurt Alexander

382

Radio frequency radiation risk: A study focused on wireless telephones  

NASA Astrophysics Data System (ADS)

The focus of this dissertation is radio frequency radiation (RFR) from wireless telephony handsets and the risk assessment conducted for purposes of protecting health from this RFR. In the United States, the Federal Communications Commission (FCC) promulgates and enforces occupational and public health exposure limits for wireless telephone handsets. The FCC has relied upon the risk assessment of the Institute of Electrical and Electronics Engineers (IEEE) Standards Coordinating Committee 28 (SCC-28) in crafting these exposure limits. Using qualitative research methods of policy analysis, the procedures used by SCC-28, the people who make up SCC-28, and the results of SCC-28 efforts were evaluated. The objective was to determine if SCC-28 adequately evaluated wireless RFR health effects research to substantiate its partial body exposure limit recommendations, those pertinent to exposure of the human head from wireless telephone handsets. This is critical because the SCC-28 recommendations have been the primary basis for FCC regulations on exposures from the wireless telephone handsets. The research methods employed were a systematic evaluation of published and unpublished comments and interview. The systematic evaluation of published and unpublished comments consisted of an analysis of records of activity in the minutes of SCC-28 as well as the collective perspectives of other knowledgeable individuals and groups in publications. This evaluation also included an in-depth literature review of hundreds of primary research publications designed to assess the nature and quality of wireless RFR health effects data available to risk assessors. Interview was accomplished using a detailed questionnaire. The National Academy of Sciences (NAS) criteria for risk assessment in the federal government were used to as the framework with which to assess the functions of SCC-28. To assess the recommendations of the results of SCC-28 risk assessment, the RFR health effects research literature was analyzed. This analysis examined whether evidence of risk was available and adequately considered in light of the judgements of authoritative individuals and organizations. Review of the health effects literature does not indicate significant risk from wireless telephone RFR, though much more research and risk assessment is needed to rule out low levels of risk. (Abstract shortened by UMI.)

Irwin, William Edward, III

383

Power absorption in electrically asymmetric dual frequency capacitive radio frequency discharges  

SciTech Connect

The symmetry of capacitive radio frequency discharges can be controlled via the electrical asymmetry effect by driving one electrode with a fundamental frequency and its second harmonic. In such electrically asymmetric discharges, the mean ion energies at both electrodes are controlled separately from the ion flux by tuning the phase angle {theta} between the harmonics at fixed voltage amplitudes. Here, the question why the ion flux is nearly independent of {theta} is answered by investigating the power absorbed by the electrons P{sub e} as a function of {theta} and time experimentally, by a particle in cell simulation, and an analytical model. The dynamics of P{sub e} is understood by the model and is found to be strongly affected by the choice of {theta}. However, on time average, P{sub e} is nearly constant, independently of {theta}. Thus, the ion flux remains approximately constant. In addition, it is shown that the absolute value of the individual voltages across the powered and grounded electrode sheath vary linearly with the dc self-bias. However, their sum remains constant. This yields, in combination with the constancy of the ion flux, a constant power absorbed by the ions and, in conclusion, a total power absorption that is independent of {theta}.

Schuengel, E.; Czarnetzki, U. [Institute for Plasma and Atomic Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Schulze, J. [Institute for Plasma and Atomic Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary); Donko, Z. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary)

2011-01-15

384

Borehole induction coil transmitter  

DOEpatents

A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

Holladay, Gale (Livermore, CA); Wilt, Michael J. (Walnut Creek, CA)

2002-01-01

385

Frequency-domain equalization of mobile radio and terrestrial broadcast channels  

Microsoft Academic Search

For mobile radio and terrestrial broadcast applications, we compare orthogonal frequency-division multiplexing (OFDM) and single-carrier transmission with frequency-domain equalization. With respect to our earlier results, we include channel coding and frequency-domain interleaving which are necessary for OFDM systems on multipath fading channels characterized by deep notches in the signal spectrum. Our results indicate that a single-carrier system with a frequency-domain

H. Sari; G. Karam; I. Jeanclaudle

1994-01-01

386

47 CFR 90.471 - Points of operation in internal transmitter control systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Points of operation in internal transmitter control systems. 90.471 Section 90.471...LAND MOBILE RADIO SERVICES Transmitter Control Internal Transmitter Control Systems § 90.471 Points of...

2013-10-01

387

47 CFR 90.473 - Operation of internal transmitter control systems through licensed fixed control points.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Operation of internal transmitter control systems through licensed fixed control points...LAND MOBILE RADIO SERVICES Transmitter Control Internal Transmitter Control Systems § 90.473 Operation of...

2013-10-01

388

47 CFR 90.461 - Direct and remote control of transmitters.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Direct and remote control of transmitters. 90.461 Section 90...PRIVATE LAND MOBILE RADIO SERVICES Transmitter Control § 90.461 Direct and remote control of transmitters. (a) In...

2010-10-01

389

47 CFR 90.461 - Direct and remote control of transmitters.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Direct and remote control of transmitters. 90.461 Section 90...PRIVATE LAND MOBILE RADIO SERVICES Transmitter Control § 90.461 Direct and remote control of transmitters. (a) In...

2011-10-01

390

Spontaneous Radio Frequency Emissions from Natural Aurora. Chapter 4  

NASA Technical Reports Server (NTRS)

At high latitudes, suitably sensitive radio experiments tuned below 5 MHz detect up to three types of spontaneous radio emissions from the Earth s ionosphere. In recent years, ground-based and rocket-borne experiments have provided strong evidence for theoretical explanations of the generation mechanism of some of these emissions, but others remain unexplained. Achieving a thorough understanding of these ionospheric emissions, accessible to ground-based experiments, will not only bring a deeper understanding of Earth s radio environment and the interactions between waves and particles in the ionosphere but also shed light on similar spontaneous emissions occurring elsewhere in Earth s environment as well as other planetary and stellar atmospheres.

LaBelle, J.

2009-01-01

391

47 CFR 22.625 - Transmitter locations.  

Code of Federal Regulations, 2013 CFR

...6? 80°11?31.2? New York, NY 40°45?6.4...transmitter location to the radio horizon in the...ii) The distance to the radio horizon is calculated using the following...is the distance to the radio horizon in kilometers h is...

2013-10-01

392

47 CFR 22.625 - Transmitter locations.  

Code of Federal Regulations, 2010 CFR

...6? 80°11?31.2? New York, NY 40°45?6.4...transmitter location to the radio horizon in the...ii) The distance to the radio horizon is calculated using the following...is the distance to the radio horizon in kilometers h is...

2010-10-01

393

47 CFR 22.625 - Transmitter locations.  

Code of Federal Regulations, 2014 CFR

...6? 80°11?31.2? New York, NY 40°45?6.4...transmitter location to the radio horizon in the...ii) The distance to the radio horizon is calculated using the following...is the distance to the radio horizon in kilometers h is...

2014-10-01

394

47 CFR 22.625 - Transmitter locations.  

Code of Federal Regulations, 2012 CFR

...6? 80°11?31.2? New York, NY 40°45?6.4...transmitter location to the radio horizon in the...ii) The distance to the radio horizon is calculated using the following...is the distance to the radio horizon in kilometers h is...

2012-10-01

395

47 CFR 22.625 - Transmitter locations.  

Code of Federal Regulations, 2011 CFR

...6? 80°11?31.2? New York, NY 40°45?6.4...transmitter location to the radio horizon in the...ii) The distance to the radio horizon is calculated using the following...is the distance to the radio horizon in kilometers h is...

2011-10-01

396

Endotoxin removal by radio frequency gas plasma (glow discharge)  

NASA Astrophysics Data System (ADS)

Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to < 0.5 EU/ml in sterile water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were repeated after employing 3-minute RFGD treatments sequentially for more than 10 cycles to observe removal of deposited matter that correlated with diminished EU titers. The results showed that 5 cycles, for a total exposure time of 15 minutes to low-temperature gas plasma, was sufficient to reduce endotoxin titers to below 0.05 EU/ml, and correlated with concurrent reduction of major endotoxin reference standard absorption bands at 3391 cm-1, 2887 cm-1, 1646 cm -1 1342 cm-1, and 1103 cm-1 to less than 0.05 Absorbance Units. Band depletion varied from 15% to 40% per 3-minute cycle of RFGD exposure, based on peak-to-peak analyses. In some cases, 100% of all applied biomass was removed within 5 sequential 3-minute RFGD cycles. The lipid ester absorption band expected at 1725 cm-1 was not detectable until after the first RFGD cycle, suggesting an unmasking of the actual bacterial endotoxin membrane induced within the gas plasma environment. Future work must determine the applicability of this low-temperature, quick depyrogenation process to medical devices of more complicated geometry than the flat surfaces tested here.

Poon, Angela

2011-12-01

397

Silicon photonic on-chip spectral shaper for ultra-broadband radio frequency arbitrary waveform generation  

Microsoft Academic Search

Silicon photonics technology attracts increasing interest in lightwave communication systems, as well as in high speed interconnection within or in-between central processing units (CPUs). A novel application of silicon photonics is in the microwave area: high carrier frequency of lightwave and ultra-compact optical devices on a silicon platform enable an integrated solution for certain broadband Radio Frequency (RF) applications, such

Hao Shen

2010-01-01

398

Dielectric properties of almond shells in the development of radio frequency and microwave pasteurization  

Technology Transfer Automated Retrieval System (TEKTRAN)

To develop pasteurization treatments based on radio frequency (RF) or microwave energy, dielectric properties of almond shells were determined using an open-ended coaxial-probe with an impedance analyzer over a frequency range of 10 to 1800 MHz. Both the dielectric constant and loss factor of almond...

399

Antennas for the Next Generation of Low-Frequency Radio Telescopes  

Microsoft Academic Search

The next generation of large telescopes for radio astronomy at frequencies below 100 MHz will consist of tens of thousands of wide-band dipole-like antennas, each individually instrumented with a receiver and combined using digital signal processing. At these frequencies, the sensitivity of a telescope is limited by Galactic noise, with the result that even simple dipoles can deliver extraordinary useable

Steven W. Ellingson

2005-01-01

400

Space Shuttle and Space Station Radio Frequency (RF) Exposure Analysis  

NASA Technical Reports Server (NTRS)

This paper outlines the modeling techniques and important parameters to define a rigorous but practical procedure that can verify the compliance of RF exposure to the NASA standards for astronauts and electronic equipment. The electromagnetic modeling techniques are applied to analyze RF exposure in Space Shuttle and Space Station environments with reasonable computing time and resources. The modeling techniques are capable of taking into account the field interactions with Space Shuttle and Space Station structures. The obtained results illustrate the multipath effects due to the presence of the space vehicle structures. It's necessary to include the field interactions with the space vehicle in the analysis for an accurate assessment of the RF exposure. Based on the obtained results, the RF keep out zones are identified for appropriate operational scenarios, flight rules and necessary RF transmitter constraints to ensure a safe operating environment and mission success.

Hwu, Shian U.; Loh, Yin-Chung; Sham, Catherine C.; Kroll, Quin D.

2005-01-01

401

Analysis of a discrete spectrum analyzer for the detection of radio frequency interference  

NASA Technical Reports Server (NTRS)

As the radio frequency spectrum becomes increasingly overcrowded, interference with mission-critical DSN operations is rising at an alarming rate. To alleviate this problem the DSN is developing a wideband surveillance system for on-site detection and identification of potential sources of radio frequency interference (RFI), which will complement the existing frequency coordination activities. The RFI monitoring system is based on a wideband, multi-look discrete spectrum analyzer operating on fast Fourier transform principles. An extensive general statistical analysis is presented of such spectrum analyzers and derives threshold detection performance formulas for signals of interest. These results are then applied to the design of the RFI spectrum analyzer under development.

Levitt, B. K.

1977-01-01

402

Dielectric properties of salmon ( Oncorhynchus keta) and sturgeon ( Acipenser transmontanus) caviar at radio frequency (RF) and microwave (MW) pasteurization frequencies  

Microsoft Academic Search

Radio frequency (RF) and microwave (MW) heating provide an important advantage of more rapid heat penetration in pasteurization processes for heat labile high value foods, which to date, have only been pasteurized by conductive heating. The objectives of this work were to determine the dielectric constant, loss factor and power penetration depth for salmon (0.8% and 2.3% total salt) and

Murad Al-Holy; Yifen Wang; Juming Tang; Barbara Rasco

2005-01-01

403

Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip.  

PubMed

Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4?ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics. PMID:25581847

Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T; Xuan, Yi; Leaird, Daniel E; Wang, Xi; Gan, Fuwan; Weiner, Andrew M; Qi, Minghao

2015-01-01

404

Reconfigurable radio-frequency arbitrary waveforms synthesized in a silicon photonic chip  

NASA Astrophysics Data System (ADS)

Photonic methods of radio-frequency waveform generation and processing can provide performance advantages and flexibility over electronic methods due to the ultrawide bandwidth offered by the optical carriers. However, bulk optics implementations suffer from the lack of integration and slow reconfiguration speed. Here we propose an architecture of integrated photonic radio-frequency generation and processing and implement it on a silicon chip fabricated in a semiconductor manufacturing foundry. Our device can generate programmable radio-frequency bursts or continuous waveforms with only the light source, electrical drives/controls and detectors being off-chip. It modulates an individual pulse in a radio-frequency burst within 4?ns, achieving a reconfiguration speed three orders of magnitude faster than thermal tuning. The on-chip optical delay elements offer an integrated approach to accurately manipulating individual radio-frequency waveform features without constraints set by the speed and timing jitter of electronics, and should find applications ranging from high-speed wireless to defence electronics.

Wang, Jian; Shen, Hao; Fan, Li; Wu, Rui; Niu, Ben; Varghese, Leo T.; Xuan, Yi; Leaird, Daniel E.; Wang, Xi; Gan, Fuwan; Weiner, Andrew M.; Qi, Minghao

2015-01-01

405

Limits on low-frequency radio emission from southern exoplanets with the Murchison Widefield Array  

NASA Astrophysics Data System (ADS)

We present the results of a survey for low-frequency radio emission from 17 known exoplanetary systems with the Murchison Widefield Array. This sample includes 13 systems that have not previously been targeted with radio observations. We detected no radio emission at 154 MHz, and put 3? upper limits in the range 15.2-112.5 mJy on this emission. We also searched for circularly polarized emission and made no detections, obtaining 3? upper limits in the range 3.4-49.9 mJy. These are comparable with the best low-frequency radio limits in the existing literature and translate to luminosity limits of between 1.2 × 1014 and 1.4 × 1017 W if the emission is assumed to be 100 per cent circularly polarized. These are the first results from a larger program to systematically search for exoplanetary emission with the MWA.

Murphy, Tara; Bell, Martin E.; Kaplan, David L.; Gaensler, B. M.; Offringa, André R.; Lenc, Emil; Hurley-Walker, Natasha; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Emrich, D.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hewitt, J. N.; Johnston-Hollitt, M.; Kasper, J. C.; Kratzenberg, E.; Lonsdale, C. J.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Ord, S. M.; Prabu, T.; Rogers, A. E. E.; Roshi, D. A.; Shankar, N. Udaya; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.

2015-01-01

406

47 CFR 22.657 - Transmitter locations.  

Code of Federal Regulations, 2014 CFR

...26.8? 95°21?37.8? New York, NY-NE NJ 40°45?06...base transmitter locations in the New York-Northeastern New Jersey urban area that...transmitter location to the radio horizon in the direction of the...

2014-10-01

407

47 CFR 22.657 - Transmitter locations.  

Code of Federal Regulations, 2010 CFR

...26.8? 95°21?37.8? New York, NY-NE NJ 40°45?06...base transmitter locations in the New York-Northeastern New Jersey urban area that...transmitter location to the radio horizon in the direction of the...

2010-10-01

408

47 CFR 22.657 - Transmitter locations.  

Code of Federal Regulations, 2013 CFR

...26.8? 95°21?37.8? New York, NY-NE NJ 40°45?06...base transmitter locations in the New York-Northeastern New Jersey urban area that...transmitter location to the radio horizon in the direction of the...

2013-10-01

409

47 CFR 22.657 - Transmitter locations.  

Code of Federal Regulations, 2012 CFR

...26.8? 95°21?37.8? New York, NY-NE NJ 40°45?06...base transmitter locations in the New York-Northeastern New Jersey urban area that...transmitter location to the radio horizon in the direction of the...

2012-10-01

410

47 CFR 22.657 - Transmitter locations.  

Code of Federal Regulations, 2011 CFR

...26.8? 95°21?37.8? New York, NY-NE NJ 40°45?06...base transmitter locations in the New York-Northeastern New Jersey urban area that...transmitter location to the radio horizon in the direction of the...

2011-10-01

411

Bi-directional 60 GHz Radio-on-Fiber Systems using Cascaded SOA-EAM Frequency Up/Down-converters  

E-print Network

/ #12;Bi-directional 60 GHz Radio-on-Fiber Systems using Cascaded SOA-EAM Frequency Up demonstrate a bi-directional 60 GHz radio-on- fiber system using a novel frequency up/down-converter based up- conversion and EAM nonlinearity is used for frequency down- conversion. Both optical LO

Choi, Woo-Young

412

Cathodoluminescence Study of GadoliniumDoped Yttrium Oxide Thin Films Deposited By RadioFrequency Magnetron Sputtering  

E-print Network

­Frequency Magnetron Sputtering J. D. Fowlkes*, P. D. Rack*, R. Bansal**, and J. M. Fitz ­ Gerald** * Dept (001) substrate using radio­frequency magnetron sputtering. Alternating layers of Y2O3 and Gd were by combinatorial sputtering using a radio­frequency magnetron sputtering system (AJA international, ATC 2000 ­ V

Fitz-Gerald, James M.

413

A review of organizations influencing radio frequency allocations to deep space research  

NASA Technical Reports Server (NTRS)

The charters and functions of various national and international scientific organizations were examined to identify those which have a direct or indirect influence on the allocation of radio frequencies for use in deep space research. Those organizations identified as having the ability to influence frequency allocations are described. A brief description of each organization is provided, and the members who are influential specifically in frequency allocations are listed. The interrelations between the organizations and how they influence allocations are explained.

1976-01-01

414

Frequency assignment in mobile radio systems using branch-and-cut techniques  

Microsoft Academic Search

We present a new exact method to plan frequency assignment for mobile radio systems in a geographical region. Frequencies are to be assigned to `cells' so that the required service is performed under the particular constraint that the overall noise–signal ratio, related to interference, should not exceed a given level for each cell–frequency pair. This NP-hard problem is formulated as

Matteo Fischetti; Chiara Lepschy; Giuseppe Minerva; Giorgio Romanin-Jacur; Ema Toto

2000-01-01

415

Excitation of a magnetospheric maser through modification of the Earth's ionosphere by high-power HF radio emission from a ground-based transmitter  

SciTech Connect

A method for controlled excitation of a magnetospheric maser through the production of artificial density ducts by high-power HF radio emission from the Earth's surface has been proposed and implemented in an in-situ experiment. Artificial density ducts allow one to affect the maser resonator system and the excitation and propagation of low-frequency electromagnetic waves in a disturbed magnetic flux tube. The experimental data presented here were obtained at the mid-latitude Sura heating facility. The characteristics of electromagnetic and plasma disturbances at outer-ionosphere altitudes were measured using the onboard equipment of the DEMETER satellite as it passed through the magnetic flux tube rested on the region of intense generation of artificial ionospheric turbulence.

Markov, G. A., E-mail: markov@rf.unn.ru; Belov, A. S., E-mail: alexis-belov@yandex.ru [Lobachevsky Nizhni Novgorod State University (Russian Federation); Frolov, V. L.; Rapoport, V. O. [Radiophysical Research Institute (Russian Federation); Parrot, M. [Environment Physics and Chemistry Laboratory (France)

2010-01-15

416

Linear transmitter design for MSAT terminals  

NASA Technical Reports Server (NTRS)

One of the factors that will undoubtedly influence the choice of modulation format for mobile satellites, is the availability of cheap, power-efficient, linear amplifiers for mobile terminal equipment operating in the 1.5-1.7 GHz band. Transmitter linearity is not easily achieved at these frequencies, although high power (20W) class A/AB devices are becoming available. However, these components are expensive and require careful design to achieve a modest degree of linearity. In this paper an alternative approach to radio frequency (RF) power amplifier design for mobile satellite (MSAT) terminals using readily-available, power-efficient, and cheap class C devices in a feedback amplifier architecture is presented.

Wilkinson, Ross; Macleod, John; Beach, Mark; Bateman, Andrew

1990-01-01

417

UTag: Long-range Ultra-wideband Passive Radio Frequency Tags  

SciTech Connect

Long-range, ultra-wideband (UWB), passive radio frequency (RF) tags are key components in Radio Frequency IDentification (RFID) system that will revolutionize inventory control and tracking applications. Unlike conventional, battery-operated (active) RFID tags, LLNL's small UWB tags, called 'UTag', operate at long range (up to 20 meters) in harsh, cluttered environments. Because they are battery-less (that is, passive), they have practically infinite lifetimes without human intervention, and they are lower in cost to manufacture and maintain than active RFID tags. These robust, energy-efficient passive tags are remotely powered by UWB radio signals, which are much more difficult to detect, intercept, and jam than conventional narrowband frequencies. The features of long range, battery-less, and low cost give UTag significant advantage over other existing RFID tags.

Dowla, F

2007-03-14

418

Radio frequency science considerations. [technology utilization of telecommunications system  

NASA Technical Reports Server (NTRS)

Use of the 400 MHz telecommunications system to obtain scientific information, to provide backup information for the experiments flown, and to obtain measurements which aid in designing future probes is considered. Recommended objectives of such a program are summarized and include: measure 400 MHz amplitude to determine adsorption and perhaps scintillation (if data rate permits); measure noise strength near 400 MHz to reexamine 400 MHz choice and to observe thermal, cosmic, and local synchrotron noise trends; probe VSWR sensing to monitor integrity of system, icing, and possible plasma effects; after the probe is finished, have the bus radio occultation in the same region where the probe fell to evaluate the occultation.

Croft, T. A.

1974-01-01

419

Non-detection at Venus of High-Frequency Radio Signals Characteristic of Terrestrial Lightning  

NASA Technical Reports Server (NTRS)

The detection of impulsive low-frequency (10 to 80 kHz) radio signals, and separate very-low-frequency (approx. 100 Hz) radio 'whistler' signals provided the first evidence for lightning in the atmosphere of Venus. Later, a small number of impulsive high- frequency (100 kHz to 5.6 MHz) radio signals, possibly due to lightning, were also detected. The existence of lightning at Venus has, however, remained controversial. Here we report the results of a search for high-frequency (0.125 to 16 MHz) radio signals during two close fly-bys of Venus by the Cassini spacecraft. Such signals are characteristic of terrestrial lightning, and are commonly heard on AM (amplitude-modulated) radios during thunderstorms. Although the instrument easily detected signals from terrestrial lightning during a later fly-by of Earth (at a global flash rate estimated to be 70/s, which is consistent with the rate expected for terrestrial lightning), no similar signals were detected from Venus. If lightning exists in the venusian atmosphere, it is either extremely rare, or very different from terrestrial lightning.

Gurnett, D. A.; Zarka, P.; Manning, R.; Kurth, W. S.; Hospodarsky, G. B.; Averkamp, T. F.; Kaiser, M. L.; Farrell, W. M.

2001-01-01

420

Resistance Compression Networks for Radio-Frequency Power Conversion  

E-print Network

A limitation of many high-frequency resonant inverter topologies is their high sensitivity to loading conditions. This paper introduces a new class of matching networks that greatly reduces the load sensitivity of resonant ...

Han, Yehui

421

Layer-like Structure of Radio-Frequency Discharge with Dust Particles  

SciTech Connect

In this paper we are carried out the computer simulation of the dust particles dynamics in the radio frequency discharges at the microgravity conditions using PIC/MCC method for electrons and ions and hydrodynamics model for dust particles. The moving of dust particles is governed by the electrostatic force, ion and neutral drag forces, which are averaged over period of RF discharge. The obtained results show that dust particles form layers with sharp boundaries in the discharge chamber that is response on the instability of the radio-frequency discharge.

Kravchenko, O. Y.; Vakulenko, A. V.; Lisitchenko, T. Y.; Levada, G. I. [National Taras Shevchenko University of Kyiv, Volodymirs'ka str. 64, 01033 Kyiv (Ukraine)

2008-09-07

422

Single shot time stamping of ultrabright radio frequency compressed electron pulses  

SciTech Connect

We demonstrate a method of time-stamping Radio Frequency compressed electron bunches for Ultrafast Electron Diffraction experiments in the sub-pC regime. We use an in-situ ultra-stable photo-triggered streak camera to directly track the time of arrival of each electron pulse and correct for the timing jitter in the radio frequency synchronization. We show that we can correct for timing jitter down to 30 fs root-mean-square with minimal distortion to the diffraction patterns, and performed a proof-of-principle experiment by measuring the ultrafast electron-phonon coupling dynamics of silicon.

Gao, M.; Dwayne Miller, R. J. [Department of Chemistry and Physics, University of Toronto, Toronto, ON. M5S 3H6 (Canada); Max Planck Research Department for Structural Dynamics, Department of Physics, Center for Free Electron Laser Science, University of Hamburg, DESY, D-22607 Hamburg (Germany); Jiang, Y.; Kassier, G. H. [Max Planck Research Department for Structural Dynamics, Department of Physics, Center for Free Electron Laser Science, University of Hamburg, DESY, D-22607 Hamburg (Germany)

2013-07-15

423

Wideband micromachined capacitive microphones with radio frequency detection  

E-print Network

, and durability associated with micromachined condenser microphones. These membranes are vacuum for calculating the expected output signal and noise level and verifies the model with measurements incorporate a condenser cartridge in a resonator and measure the resulting amplitude, frequency, or phase

Khuri-Yakub, Butrus T. "Pierre"

424

Fiber-based Radio Frequency Dissemination for Branching Networks with Passive Phase Noise Cancellation  

E-print Network

We demonstrate a new fiber-based radio frequency dissemination scheme for branching networks. Without any phase controls on RF signals or usages of active feedback locking components, the highly stable reference frequency signal can be delivered to several remote sites simultaneously and independently. Relative frequency stability of 6E-15/s and 7E-17/1E4s is obtained for 10km dissemination. The proposed low cost and scalable method can be applied to some large-scale frequency synchronization networks.

Bai, Y; Gao, C; Miao, J; Zhu, X; Wang, L J

2015-01-01

425

A Voltage Controlled Oscillator for a Phase-Locked Loop Frequency Synthesizer in a Silicon-on-Sapphire Process  

E-print Network

Engineers from a government-owned engineering and manufacturing facility were contracted by government-owned research laboratory to design and build an S-band telemetry transmitter using Radio Frequency Integrated Circuit ...

Garrison, Sean Michael

2009-05-22

426

Modeling of radio frequency electromagnetic disturbances in power line communication networks  

Microsoft Academic Search

This paper proposes a new approach to modeling the radio frequency (RF) electromagnetic disturbances in broadband power line communication (PLC) networks using the multi-conductor transmission line (MTL) theory. The model includes a differential-mode (DM) current propagation model and a common-mode (CM) current propagation model. The frequency range of interest is from 1 MHz to 30 MHz. Practical measurements are carried

Teng Seng Pang; Ping Lam So; Kye Yak See

2008-01-01

427

Dielectric Properties of Mashed Potatoes Relevant to Microwave and Radio-frequency Pasteurization and Sterilization Processes  

Microsoft Academic Search

Dielectric properties of mashed potatoes relevant to microwave and radio-frequency (RF) pasteuriza- tion and sterilization processes were measured over 1 to 1800 MHz and 20 °C to 120 °C. Effects of moisture content (81.6% to 87.8%, wb) and salt content (0.8% to 2.8%, wb) were investigated. Dielectric loss factors and constants decreased with frequency. Dielectric loss factors increased with temperature

D. G UAN; M. CHENG; Y. WANG; J. TANG

2004-01-01

428

Dual-frequency focused ultrasound using optoacoustic and piezoelectric transmitters for single-pulsed free-field cavitation in water  

NASA Astrophysics Data System (ADS)

Pulsed ultrasonic cavitation is a promising modality for non-contact targeted therapy, enabling mechanical ablation of the tissue. We demonstrate a spatio-temporal superposition approach of two ultrasound pulses (high and low frequencies) producing a tight cavitation zone of 100 ?m in water, which is an-order-of-magnitudes smaller than those obtained by the existing high-amplitude transducers. Particularly, laser-generated focused ultrasound (LGFU) was employed for the high-frequency operation (15 MHz). As demonstrated, LGFU plays a primary role to define the cavitation zone. The generation rate of cavitation bubbles could be dramatically increased up to 4.1% (cf. 0.06% without the superposition) with moderated threshold requirement.

Baac, Hyoung Won; Lee, Taehwa; Ok, Jong G.; Hall, Timothy; Jay Guo, L.

2013-12-01

429

Plasma sheath structures around a radio frequency antenna  

NASA Astrophysics Data System (ADS)

A one-dimensional particle-in-cell (PIC) simulation code is developed to investigate plasma sheath structures around a high-voltage transmitting antenna in the inner magnetosphere. We consider an electrically short dipole antenna assumed to be bare and perfectly conducting. The oscillation frequency of the antenna current is chosen to be well below the electron plasma frequency but higher than the ion plasma frequency. The magnetic field effects are neglected in the present simulations. Simulations are conducted for the cases without and with ion dynamics. In both cases, there is an initial period, about one-fourth of an oscillation cycle, of antenna charging because of attraction of electrons to the antenna and the formation of an ion plasma sheath around the antenna. With the ion dynamics neglected, the antenna is charged completely negatively so that no more electrons in the plasma can reach the antenna after the formation of the sheath. When the ion dynamics are included, the electrons impulsively impinge upon the antenna while the ions reach the antenna in a continuous manner. In such a case, the antenna charge density and electric field have a brief excursion of slightly positive values during which there is an electron sheath. The electron and ion currents collected by the antenna are weak and balance each other over each oscillation cycle. The sheath-plasma boundary is a transition layer with fine structures in electron density, charge density, and electric field distributions. The sheath radius oscillates at the antenna current frequency. The calculated antenna reactance is improved from the theoretical value by 10%, demonstrating the advantage of including the plasma sheath effects self-consistently using the PIC simulations. The sheath tends to shield the electric field from penetrating into the plasma. There is, however, leakage of an electric field component with significant amplitude into the plasma, implying the applicability of the high-voltage antennas in whistler wave transmission in the inner magnetosphere.

Tu, Jiannan; Song, Paul; Reinisch, Bodo W.

2008-07-01

430

Dielectric properties of human fetal organ tissues at radio frequencies.  

PubMed

The in vitro dielectric properties of human fetal organ tissues were measured in the frequency range from 100 kHz to 500 MHz at 24 degrees C. The dielectric measurements were performed by using a network analyzer (HP4195A) and a coaxial line capacitive sensor. The tested samples, including skin, muscle, heart, lung, liver, kidney, spleen, and brain tissues, were obtained from the legal abortion of five women with 14-16 weeks gestation periods. PMID:8915552

Lu, Y; Cui, H; Yu, J; Mashimo, S

1996-01-01

431

Studies of High-Frequency Radio Wave Propagation  

Microsoft Academic Search

Studies of multiple signals of high frequency have been made upon a quantitative basis with reference not only to the round-the-world signals (sometimes called echo signals) but to nearby echoes which have a very much shorter time of arrival. A method of predicting in advance the the likelihood of round-the-world echoes occurring between any two different stations has been worked

A. H. Taylor; L. C. Young

1928-01-01

432

High Frequency Radio Recombination Lines in Starburst Galaxies  

NASA Astrophysics Data System (ADS)

The observation of radio recombination lines (RRL) over a wide range of quantum levels gives valuable information on the physical state of the ionized gas. With the sensitivity of the existing radiotelescopes, at long as well as at short wavelengths, only less than 10 galaxies have been detected. The most distant galaxy detected so far is the starburst galaxy Arp 220. The remarkable feature in observing millimeter RRLs is that they allow to probe high density regions although this represent only a small fraction of the total mass of ionized gas. Starburst nuclei are heavily obscured in the visible but also in the near infrared, RRLs offer probably the unique tool to measure recent star formation rate (SFR). Centimeter lines can be used to determine the average SFR on a time scale of ~ 5 106 years while the millimeter lines offer the access to the very instantaneous SFR rate ( ~105 years). The total infrared luminosity is related to the average SFR on longer time scales, a few 107 years. Hence a multi-wavelength approach gives informations about the star formation history. Some recent results are presented. They illustrate the potentiality of ALMA which will have the sensitivity to detect a large number of galaxies and at much larger distances.

Viallefond, François; Anantharamiah, K. R.

1999-10-01

433

The low-frequency environment of the Murchison Widefield Array: radio-frequency interference analysis and mitigation  

E-print Network

The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array (SKA). We describe the automated radio-frequency interference (RFI) detection strategy implemented for the MWA, which is based on the AOFlagger platform, and present 72-231-MHz RFI statistics from 10 observing nights. RFI detection removes 1.1% of the data. RFI from digital TV (DTV) is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After RFI detection and excision, almost all data can be calibrated and imaged without further RFI mitigation efforts, including observations within the FM and DTV bands. The results are compared to a previously published Low-Frequency Array (LOFAR) RFI survey. The remote location of the MWA results in a substantially cleaner RFI environment compared to LOFAR's radio environment, but adequate detection of RFI is still required before data can be analysed. We include speci...

Offringa, A R; Hurley-Walker, N; Kaplan, D L; Barry, N; Beardsley, A P; Bell, M E; Bernardi, G; Bowman, J D; Briggs, F; Callingham, J R; Cappallo, R J; Carroll, P; Deshpande, A A; Dillon, J S; Dwarakanath, K S; Ewall-Wice, A; Feng, L; For, B -Q; Gaensler, B M; Greenhill, L J; Hancock, P; Hazelton, B J; Hewitt, J N; Hindson, L; Jacobs, D C; Johnston-Hollitt, M; Kapi?ska, A D; Kim, H -S; Kittiwisit, P; Lenc, E; Line, J; Loeb, A; Lonsdale, C J; McKinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Morgan, J; Neben, A R; Oberoi, D; Ord, S M; Paul, S; Pindor, B; Pober, J C; Prabu, T; Procopio, P; Riding, J; Shankar, N Udaya; Sethi, S; Srivani, K S; Staveley-Smith, L; Subrahmanyan, R; Sullivan, I S; Tegmark, M; Thyagarajan, N; Tingay, S J; Trott, C M; Webster, R L; Williams, A; Williams, C L; Wu, C; Wyithe, J S; Zheng, Q

2015-01-01

434

Observation of parametric instabilities in lower-hybrid radio-frequency heating of Tokamaks  

Microsoft Academic Search

Experimental data are presented which show that during lower-hybrid radio-frequency heating of an adiabatic-toroidal-compressor Tokamak, parametric instabilities are excited, and the ion heating correlates with the presence of the parametric spectra. A theoretical interpretation of the parametric instabilities is presented.

M. Porkolab; S. Bernabei; W. M. Hooke; R. W. Motley; T. Nagashima

1977-01-01

435

Holme et al. Soil Redox Sensor Networks RADIO FREQUENCY ENABLED SOIL REDOX POTENTIAL  

E-print Network

Holme et al. Soil Redox Sensor Networks RADIO FREQUENCY ENABLED SOIL REDOX POTENTIAL SENSOR technologies that may be combined into a cost effective soil redox sensor network, discuss the merits of each as a component of said network, describe a prototype soil redox sensor network and perform basic laboratory

Rubinstein, Benjamin

436

The standing wave phenomenon in radio telescopes. Frequency modulation of the WSRT primary beam  

Microsoft Academic Search

Context: Inadequacies in the knowledge of the primary beam response of current interferometric arrays often form a limitation to the image fidelity, particularly when ``mosaicing'' over multiple telescope pointings. Aims: We hope to overcome these limitations by constructing a frequency-resolved, full-polarization empirical model for the primary beam of the Westerbork Synthesis Radio Telescope (WSRT). Methods: Holographic observations, sampling angular scales

Attila Popping; Robert Braun

2008-01-01

437

Industrial-scale radio frequency treatments for insect control in lentils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Radio frequency (RF) treatments are considered to be a potential postharvest technology for disinfesting legumes of internal seed pests such as the cowpea weevil. After treatment protocols are shown to control postharvest insects without significant quality degradation, it is important to scale-up l...

438

Determining radio frequency heating uniformity of mixed beans for disinfestation treatments  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chickpeas and lentils are two important legumes grown in the US and need phytosanitary treatments before exportation, but it is difficult to artificially infest them with live cowpea weevil for radio frequency (RF) treatment validation. To evaluate the more readily infested black-eyed peas and mung ...

439

Influence of Temperature in Radio Frequency Measurements of Moisture Content in Biofuel  

Microsoft Academic Search

A method that permits the determination of moisture content in biofuel in a fast and representative way is under development. The method uses radio frequency waves within the range of 310 MHz to 800 MHz and measures the reflection coefficient in samples with volume of about 0.1 m3. The influence of sample temperature in the measurements is shown in this

Ana Paz; Jenny Nyström; Eva Thorin

2006-01-01

440

A Quantum Theory of the Biological Effects of Radio-frequencies and its application to Cancer  

E-print Network

-term exposure to a wide- band electromagnetic wave could cure cancer [33] [41]. Possible effects on the immuneA Quantum Theory of the Biological Effects of Radio-frequencies and its application to Cancer of artificial electromagnetic waves on various classes of diseases. Theoretical predictions concerning cancer

Paris-Sud XI, Université de

441

Scheme to funnel ion beams with a radio-frequency quadrupole  

SciTech Connect

We describe a proposed method to funnel ion beams using a new form of the radio-frequency quadrupole (RFQ) structure. This RFQ accepts two bunched ion beams and combines them into a single final beam with interlaced microstructure pulses. It also provides uninterrupted periodic transverse focusing to facilitate the funneling of beams with high current and low emittance.

Stokes, R.H.; Minerbo, G.N.

1985-01-01

442

MARINER 9 SPACE PROBE ATOP ATLAS CENTAUR UNDERGOES RADIO FREQUENCY INTERFERENCE TESTS  

NASA Technical Reports Server (NTRS)

An Atlas-Centaur rocket undergoes radio frequency interference tests at Cape Kennedy's Complex 36B prior to launch to Mars. The spacecraft was launched on a five and one-half month journey to mars, where it will enter orbit and return data about that planet's surface and atmosphere. Launch took place at 6:23 p.m. EDT, May 30, 1971.

1971-01-01

443

Calibration of electromagnetic calorimeters in high energy experiments with a Radio Frequency Quadrupole accelerator  

Microsoft Academic Search

A fast, effective calibration technique has been developed for future Superconducting Supercollider (SSC) calorimeters based upon the radiative capture of protons from a pulsed Radio Frequency Quadrupole (RFQ) accelerator in a fluoride target. The intense flux of low energy photons acts as a clean ``pulse generator'' calibration signal equivalent to 20 GeV or more. This calibration technique has been demonstrated

H. Ma; H. Newman; R. Y. Zhu; R. Hamm

1989-01-01

444

Dynamics of ion-ion plasmas under radio frequency bias Vikas Midhaa)  

E-print Network

Dynamics of ion-ion plasmas under radio frequency bias Vikas Midhaa) and Demetre J. Economoub-dimensional fluid model was developed to study the dynamics of a positive ion-negative ion ion-ion plasma under the influence of a rf bias voltage. The full ion momentum and continuity equations were coupled to the Poisson

Economou, Demetre J.

445

Performance Bounds of MIMO Receivers in the Presence of Radio Frequency Interference  

E-print Network

the non-linear phenomenon governing electromagnetic interference (EMI), and explicitly include a GaussianPerformance Bounds of MIMO Receivers in the Presence of Radio Frequency Interference Aditya Chopra interference (RFI) that is well modeled using non- Gaussian impulsive statistics. In this paper, we derive

Evans, Brian L.

446

Research of Radio-Frequency Electric Discharge in Electrolyte in the Processes of Surface Treatment  

NASA Astrophysics Data System (ADS)

The object of this research is radio-frequency electric discharge in electrolyte in the processes of surface treatment of materials. The forms and structures of electric discharge, the results of X-ray structure analysis, metallographic analysis of surface samples before and after treatment are presented in the article.

Gaisin, Al F.; Abdullin, I. Sh; Basyrov, R. Sh; Petriakov, S. Y.

2014-11-01

447

Large area radio frequency plasma for microelectronics processing Z. Yu and D. Shaw  

E-print Network

Large area radio frequency plasma for microelectronics processing Z. Yu and D. Shaw Colorado State spatially confined high density gas discharge plasmas for microelectronics processing. Commercial processing, the dielectric window design is only focused on materials for the given process chemistry to be placed between

Collins, George J.

448

Temporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath  

E-print Network

with existing theory. The large temporal variation of the IVDF has implications for the plasma chemistry and increases the energy of ions incident upon the sub- strate. For industrial plasma processing of poorlyTemporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath B

California at Los Angles, University of

449

Method of Studying Travel Time Anomalies of High Frequency Radio Waves  

Microsoft Academic Search

A device utilizing pulse techniques has been built for automatic measurement of changes in radio wave travel times. The equipment uses a combination of amplitude, time, and frequency selection for discrimination against unwanted signals. The received signals from U. S. time standard station WWV are sampled at 1-sec intervals to measure changes in the time of reception of the 1-sec

Gordon Lerfald; Paul Scheibe

1960-01-01

450

A Low-Frequency Distributed Aperture Array for Radio Astronomy in Space  

Microsoft Academic Search

The frequency band below 30 MHz is one of the last unexplored bands in radio astronomy. This band is well suited for studying the early cosmos at high hydrogen redshifts, the so-called dark ages, extragalactic surveys, (extra) solar planetary bursts, and high energy particle physics. In addition, space research such as space weather tomography, are also areas of scientific interest.

Albert-Jan Boonstra; Noah Saks; Heino Falcke; Marc Klein-Wolt; Ark Bentum; Raj Thilak Rajan; Ir. Stefan J. Wijnholds; Michel Arts; Kees van-T Klooster; Frederik Belien

2010-01-01

451

Pulsed Discharge Effects on Bacteria Inactivation in Low-Pressure Radio-Frequency Oxygen Plasma  

Microsoft Academic Search

The sporicidal effects of low-pressure radio frequency (RF) discharges in oxygen, produced by the application of continuous and pulsed RF power, were evaluated. For all cases, the survival curves showed a biphasic evolution. The maximum efficiency for bacteria sterilization was obtained when the RF power was injected in the continuous wave mode, while in the pulsed mode the lowest treatment

Dragos Vicoveanu; Yasunori Ohtsu; Hiroharu Fujita

2008-01-01

452

Characterization of ? and ? modes in radio-frequency nonthermal atmospheric plasmas  

Microsoft Academic Search

Summary form only given. Nonthermal atmospheric gas discharges generated at radio frequencies have recently commanded much interest because of their immense potential for numerous applications such as etching, deposition, surface modification and sterilization. Through several detailed studies, much has been gained in the understanding of their basic electrical characteristics, their optical emission and their reaction chemistry. These studies are typically

J. J. Shi; M. G. Kong

2004-01-01

453

Radio-Frequency Glow Discharges of Different Gases Using Bare Metallic Electrodes at Atmospheric Pressure  

Microsoft Academic Search

The images of the atmospheric-pressure glow discharges driven by the radio-frequency power supply using He, Ar, N2, O2, air, or their mixture as the primary plasma-working gas are presented in this paper. The plasma jet, produced using the planar-type plasma generator behaving like a \\

He-Ping Li; Guo Li; Sen Wang; Pei-Si Le; Cheng-Yu Bao

2008-01-01

454

Comparison of an atmospheric pressure, radio-frequency discharge operating in the ? and ? modes  

Microsoft Academic Search

The ? and ? modes of an atmospheric pressure, radio-frequency plasma have been investigated. The plasma source consisted of two parallel electrodes that were fed with helium and 0.4 vol% nitrogen. The transition from ? to ? was accompanied by a 40% drop in voltage, a 12% decrease in current and a surge in power density from 25 to 2083

X Yang; M Moravej; G R Nowling; S E Babayan; J Panelon; J P Chang; R F Hicks

2005-01-01

455

Integrated radio frequency identification and wireless sensor network architecture for automated inventory management and tracking applications  

Microsoft Academic Search

We provide a system architecture that applies radio frequency identification and wireless sensor network technologies to automate inventory management and tracking of commercial assets. A set of environment parameters are considered as a result of the environment for which this application serves. To meet system design constraints and application requirements, a system architecture is proposed that automates inventory management and

Mark L. McKelvin Jr.; Mitchel L. Williams; Nina M. Berry

2005-01-01

456

Quasilinear theory of collisionless electron heating in radio frequency gas discharges  

E-print Network

parameters. Due to the large value of the mean free path MFP the main mechanism of electron heating turns outQuasilinear theory of collisionless electron heating in radio frequency gas discharges Yu. M. Aliev heating of rf discharges is treated for characteristic scale lengths of the heating field much shorter

Kaganovich, Igor

457

Interactions of magnetic resonance imaging radio frequency magnetic fields with elongated medical implants  

Microsoft Academic Search

Magnetic resonance imaging (MRI) is a well established diagnostic technique, one from which all patients should be able to benefit, including those with implanted medical devices. This paper describes an experimental and numerical study of the temperature rise near the ends of wires by the radio frequency (rf) field in MRI. These wires simulate long wires which may be part

Chris D. Smith; Alexander V. Kildishev; John A. Nyenhuis; Kirk S. Foster; Joe D. Bourland

2000-01-01

458

DIFFERENTIAL HEATING OF INSECTS IN DRIED NUTS AND FRUITS ASSOCIATED WITH RADIO FREQUENCY AND MICROWAVE TREATMENTS  

Microsoft Academic Search

This research was conducted to provide a theoretical basis and experimental evidence to support the hypothesis that insect larvae can be preferentially heated in dry nuts and fruits by radio frequency (RF) heating for pest control. We selected codling moth larvae as the target insect and in-shell walnuts as the host material for this study, and focused our attention on

S. Wang; J. Tang; R. P. Cavalieri; D. C. Davis

459

Industrial-scale radio frequency treatments for insect control in in-shell walnuts  

Technology Transfer Automated Retrieval System (TEKTRAN)

Prior to the 2005 ban, in-shell walnuts were routinely fumigated with methyl bromide for insect control before export. Several pilot scale radio frequency (RF) studies have been reported as a new technology to completely control the most heat resistant insect, navel orangeworms, in in-shell walnuts ...

460

Determining radio frequency heating uniformity of mixed beans during disinfestation treatments  

Technology Transfer Automated Retrieval System (TEKTRAN)

Since chickpeas and lentils are difficulty to artificially infest with live insects for radio frequency (RF) treatment validation, black-eyed peas and mung beans were selected to infest with insects before mixing with chickpeas and lentils. Temperature difference between black-eyed pea and chickpea ...

461

IMPROVED TECHNIQUE FOR MONITORING ELECTROCARDIOGRAMS DURING EXPOSURE TO RADIO-FREQUENCY RADIATION  

EPA Science Inventory

Studies were conducted which examined the effects of radio frequency (RF) radiation on heart rate (HR), deep body temperature (TEMP), and electrocardiographic (ECG) waveform parameters in anesthetized rats. One group of animals was exposed to two power levels of continuous wave R...

462

Radio-frequency superradiance at the rheological explosion of a paramagnetic polymer composite containing manganese complexes  

NASA Astrophysics Data System (ADS)

It has been revealed that the rheological explosion of a paramagnetic composite (manganese (III) polystyrene acetylacetonate—spatially complicated phenol) is accompanied by the generation of radio-frequency superradiance owing to the annihilation of triplet manganese complexes, as well as by the generation of current pulses.

Aleksandrov, A. I.; Alexandrov, I. A.; Prokof'ev, A. I.

2013-07-01

463

The Miniature Radio Frequency instrument's (Mini-RF) global observations of Earth's Moon  

E-print Network

Comment The Miniature Radio Frequency instrument's (Mini-RF) global observations of Earth's Moon: Moon Radar observations Cratering Volcanism a b s t r a c t Radar provides a unique means to analyze on the Moon at a global scale. Mini-RF has accu- mulated $67% coverage of the lunar surface in S-band (12.6 cm

Spudis, Paul D.

464

New optical and radio frequency angular tropospheric refraction models for deep space applications  

NASA Technical Reports Server (NTRS)

The development of angular tropospheric refraction models for optical and radio frequency usage is presented. The models are compact analytic functions, finite over the entire domain of elevation angle, and accurate over large ranges of pressure, temperature, and relative humidity. Additionally, FORTRAN subroutines for each of the models are included.

Berman, A. L.; Rockwell, S. T.

1976-01-01

465

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy  

E-print Network

Surface reconstructions of cubic gallium nitride ,,001... grown by radio frequency nitrogen plasma molecular beam epitaxy under gallium-rich conditions Muhammad B. Haider, Rong Yang, Costel Constantin; published online 27 October 2006 Cubic GaN has been grown under gallium Ga -rich growth conditions using

466

Simulations of the Radio Frequency Signals Produced by Electromagnetic Showers in Ice  

NASA Astrophysics Data System (ADS)

We report our recently up dated study of Cherenkov signals at radio frequencies from high energy electromagnetic showers in ice using GEANT based Monte Carlo simulations. Our results are used in calibrating the ultrahigh energy neutrino detection experiment RICE at the South Pole.

Razzaque, S.; Seunarine, S.; Chambers, S. W.; Besson, D. Z.; McKay, D. W.; Ralston, J. P.; Seckel, D.

2003-07-01

467

Research and application of radio frequency identification (RFID) technology to enhance aviation security  

Microsoft Academic Search

Radio frequency identification (RFID) is an automatic identification technology similar in some ways to barcode technology. There are several different types of RFID prototype systems currently being developed to support all aspects of aviation baggage tracking, sortation, and reconciliation. Several operational test programs have taken place, including those sponsored by and conducted by the FAA, in an effort to determine

A. Cerino; W. P. Walsh

2000-01-01

468

A candidate active antenna design for a low frequency radio telescope array  

Microsoft Academic Search

The Long Wavelength Array (LWA), currently in the development stage, is a radio telescope array that will be constructed in New Mexico, USA over the next several years. It will consist of ~ 52 stations of ~ 256 cross-dipole antennas each, and will explore the Universe in the 20 - 80 MHz frequency band. The large number of antennas required

Nagini Paravastu; Brian Hicks; P. Ray; W. Erickson

2007-01-01

469

A COMBINED LOW-RADIO FREQUENCY/X-RAY STUDY OF GALAXY GROUPS. I. GIANT METREWAVE RADIO TELESCOPE OBSERVATIONS AT 235 MHz AND 610 MHz  

SciTech Connect

We present new Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz of 18 X-ray bright galaxy groups. These observations are part of an extended project, presented here and in future papers, which combines low-frequency radio and X-ray data to investigate the interaction between central active galactic nuclei (AGNs) and the intra-group medium (IGM). The radio images show a very diverse population of group-central radio sources, varying widely in size, power, morphology, and spectral index. Comparison of the radio images with Chandra and XMM-Newton X-ray images shows that groups with significant substructure in the X-ray band and marginal radio emission at {approx}>1 GHz host low-frequency radio structures that correlate with substructures in IGM. Radio-filled X-ray cavities, the most evident form of AGN/IGM interaction in our sample, are found in half of the systems and are typically associated with small, low-, or mid-power double radio sources. Two systems, NGC5044 and NGC4636, possess multiple cavities, which are isotropically distributed around the group center, possibly due to group weather. In other systems the radio/X-ray correlations are less evident. However, the AGN/IGM interaction can manifest itself through the effects of the high-pressure medium on the morphology, spectral properties, and evolution of the radio-emitting plasma. In particular, the IGM can confine fading radio lobes in old/dying radio galaxies and prevent them from dissipating quickly. Evidence for radio emission produced by former outbursts that co-exist with current activity is found in six groups of the sample.

Giacintucci, Simona [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); O'Sullivan, Ewan; Vrtilek, Jan; David, Laurence P.; Mazzotta, Pasquale; Gitti, Myriam; Jones, Christine; Forman, William R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Raychaudhury, Somak; Ponman, Trevor [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Venturi, Tiziana [INAF-Istituto di Radioastronomia, via Gobetti 101, I-40129, Bologna (Italy); Athreya, Ramana M. [IISER, Pune, Maharashtra 411 008 (India); Clarke, Tracy E. [Naval Research Laboratory, 4555 Overlook Avenue SW, Code 7213, Washington, DC 20375 (United States); Murgia, Matteo [INAF-Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, I-09012 Capoterra (Italy); Ishwara-Chandra, C. H., E-mail: simona@astro.umd.edu [National Centre for Radio Astrophysics, TIFR, Post Bag No. 3, Ganeshkhind, Pune 411 007 (India)

2011-05-10

470

2012 REU Project Abstracts Identifying Fluids for Tuning and Cooling Radio Frequency Devices Operating in the X-Band  

E-print Network

2012 REU Project Abstracts Identifying Fluids for Tuning and Cooling Radio Frequency Devices Franklin The objective is to identify fluids with potential to be used as heat transfer mediums and tuning materials in micrometer-sized radio frequency devices. Fluids used in these types of devices must exhibit

Minnesota, University of

471

Method for calculating certain characteristics of radio-wave propagation using inclination angles of plasma-frequency isolines  

Microsoft Academic Search

The paper describes a method for calculating azimuthal deviations and Doppler frequency shifts in the ionosphere on the basis of inclination angles of plasma-frequency isolines. The method is applicable to ionospheric radio lines under the effect of traveling ionospheric disturbances moving at an angle of 90 deg to the radio-line direction.

G. N. Nosova

1985-01-01

472

Goniopolarimetric study of the revolution 29 perikrone using the Cassini Radio and Plasma Wave Science instrument high-frequency radio receiver  

Microsoft Academic Search

We present goniopolarimetric (also known as direction finding) results of the Saturn kilometric radiation (SKR), using the Cassini Radio and Plasma Wave Science instrument high-frequency radio receiver data. Tools to retrieve the characteristics of the SKR sources have been developed that allow us to measure their 3-D location and beaming angle relative to the magnetic field in the source and,

B. Cecconi; L. Lamy; P. Zarka; R. Prangé; W. S. Kurth; P. Louarn

2009-01-01

473

SEMICONDUCTOR INTEGRATED CIRCUITS: A 3.1-4.8 GHz transmitter with a high frequency divider in 0.18 ?m CMOS for OFDM-UWB  

NASA Astrophysics Data System (ADS)

A fully integrated low power RF transmitter for a WiMedia 3.1-4.8 GHz multiband orthogonal frequency division multiplexing ultra-wideband system is presented. With a separate transconductance stage, the quadrature up-conversion modulator achieves high linearity with low supply voltage. The co-design of different resonant frequencies of the modulator and the differential to single (D2S) converter ensures in-band gain flatness. By means of a series inductor peaking technique, the D2S converter obtains 9 dB more gain without extra power consumption. A divided-by-2 divider is used for carrier signal generation. The measurement results show an output power between -10.7 and -3.1 dBm with 7.6 dB control range, an OIP3 up to 12 dBm, a sideband rejection of 35 dBc and a carrier rejection of 30 dBc. The ESD protected chip is fabricated in the Jazz 0.18 ?m RF CMOS process with an area of 1.74 mm2 and only consumes 32 mA current (at 1.8 V) including the test associated parts.

Renliang, Zheng; Junyan, Ren; Wei, Li; Ning, Li

2009-12-01

474

Radar activities of the DFVLR Institute for Radio Frequency Technology  

NASA Technical Reports Server (NTRS)

Aerospace research and the respective applications microwave tasks with respect to remote sensing, position finding and communication are discussed. The radar activities are directed at point targets, area targets and volume targets; they center around signature research for earth and ocean remote sensing, target recognition, reconnaissance and camouflage and imaging and area observation radar techniques (SAR and SLAR). The radar activities cover a frequency range from 1 GHz up to 94 GHz. The radar program is oriented to four possible application levels: ground, air, shuttle orbits and satellite orbits. Ground based studies and measurements, airborne scatterometers and imaging radars, a space shuttle radar, the MRSE, and follow on experiments are considered.

Keydel, W.

1983-01-01

475

Power spectra at radio frequency of lightning return stroke waveforms  

NASA Technical Reports Server (NTRS)

The power spectra of the wideband (10 Hz to 100 kHz) magnetic field signals in a number of lightning return strokes (primarily first return strokes) measured during a lightning storm which occurred in Lindau, West Germany in August, 1984 have been calculated. The RF magnetic field data were obtained with the engineering unit of the Galileo Jupiter Probe lightning experiment. The spectra of the magnetic field data definitely show fine structure, with two or three distinct peaks appearing in the spectra of many of the waveforms. An enhancement of power at frequencies of about 60-70 kHz is often seen in the spectra of the waveform time segments preceding and following the rise-to-peak amplitude of the return stroke.

Lanzerotti, L. J.; Thomson, D. J.; Maclennan, C. G.; Rinnert, K.; Krider, E. P.

1989-01-01

476

Response of radio frequency superconducting quantum interference devices to electromagnetic interference  

SciTech Connect

A number of applications of high-temperature superconductor radio frequency superconducting quantum interference devices (rf SQUIDs) require a certain immunity of these sensors against electromagnetic interference (EMI). We have investigated effects of electromagnetic radiation in the high-frequency and ultrahigh-frequency range on various types of rf SQUIDs. It has been found that EMI of sufficient field strength reduces the voltage versus flux transfer function, and thus increases the flux noise of the SQUIDs. SQUIDs with a wire wound tank circuit coil have been found to be more sensitive to EMI than SQUIDs integrated into a superconducting microstrip resonator. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Mueck, M.; Dechert, J.; Gail, J.; Kreutzbruck, M.; Schoene, S.; Weidl, R. [Institut fuer Angewandte Physik, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)] [Institut fuer Angewandte Physik, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

1995-09-01

477

Long-term study of 435 MHz radio-frequency radiation on blood-borne end points in cannulated rats. Part I: Engineering considerations.  

PubMed

To study the effects of exposure to long-term, low-level radio-frequency radiation (RFR) on various physiological systems in a large population of rodents, a complete exposure facility was designed and constructed at the Georgia Institute of Technology. The major components of the facility included a set of circular, stacked, parallel-plate waveguides fed by slotted-cylinder antennas. The waveguides provided a TE10 mode, horizontally polarized field in which the maximal power density occurred midway between the parallel plates. The feed antenna and the parallel-plate waveguides generated a field that radiated outward and was uniform in the azimuthal plane. Thus, animals arrayed along the periphery of the plates were exposed to a uniform 1.0 mW/cm2 field (1.0 microsecond pulse width, 1 kHz pulse repetition rate, 435 MHz carrier). The facility transmitter provided four channels of 435 MHz RFR at 200 W average (continuous wave) or 5 kW peak (pulsed-wave) power; in addition, the transmitter outputs could be combined into a single channel capable of energizing one tier of the stacked parallel-plate waveguide system at 800 W continuous wave or at 16 kW of pulsed waves. To individually house the 200 rodents involved in the study, both biological and engineering criteria were examined and used to design and construct special Plexiglas cages. PMID:3193342

Bonasera, S; Toler, J; Popovic, V

1988-01-01

478

Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering  

NASA Astrophysics Data System (ADS)

We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (Ts). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10-3 ? cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at Ts of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein-Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ˜110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K.

2013-10-01

479

Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering  

SciTech Connect

We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (T{sub s}). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10{sup ?3} ? cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at T{sub s} of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein–Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ?110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K. [Center for Materials Research, Norfolk State University, 700 Park Avenue, Norfolk, Virginia 23504 (United States)] [Center for Materials Research, Norfolk State University, 700 Park Avenue, Norfolk, Virginia 23504 (United States)

2013-10-14

480

Utilization of photon orbital angular momentum in the low-frequency radio domain.  

PubMed

We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (< or = 1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts. PMID:17930983

Thidé, B; Then, H; Sjöholm, J; Palmer, K; Bergman, J; Carozzi, T D; Istomin, Ya N; Ibragimov, N H; Khamitova, R

2007-08-24

481

URSI workshop report - Effects of the lower atmosphere on radio propagation at frequencies above 1 GHz  

NASA Astrophysics Data System (ADS)

The URSI workshop which investigated the effects of the lower atmosphere on radio propagation at frequencies above 1 GHz is summarized. Topics of the workshop include scattering from hydrometeors, predicting attenuation due to rainfall on terrestrial links, clear air propagation on line-of-sight radio paths, cross polarization on terrestrial and earth-space links, and transhorizon propagation. Exact calculations of electromagnetic wave scattering by single hydrometeors are given, and recommendations are made to develop a better characterization of cross polarization in clear-air and precipitation conditions.

Holt, A. R.; Hall, M. P. M.; Boithias, L.; Strickland, J.; Paraboni, A.; Bostian, C.; Ochs, A.

1981-10-01

482

Relations among low ionosphere parameters and high frequency radio wave absorption  

NASA Technical Reports Server (NTRS)

Charged particle conductivities measured in the very low ionosphere at White Sands Missile Range, New Mexico, and Wallops Island, Virginia, are compared with atmospheric parameters and high frequency radio wave absorption measurements. Charged particle densities are derived from the conductivity data. Between 33 and 58 km, positive conductivity correlated well with neutral atmospheric temperature, with temperature coefficients as large as 4.6%/deg K. Good correlations were also found between HF radio wave absorption and negative conductivity at altitudes as low as 53 km, indicating that the day-to-day absorption variations were principally due to variations in electron loss rate.

Cipriano, J. P.

1973-01-01

483

FREQUENCY DEPENDENCE OF THE POWER-LAW INDEX OF SOLAR RADIO BURSTS  

SciTech Connect

We process solar flare observations of Nobeyama Radio Polarimeters with an improved maximum likelihood method developed recently by Clauset et al. The method accurately extracts power-law behaviors of the peak fluxes in 486 radio bursts at six frequencies (1-35 GHz) and shows an excellent performance in this study. The power-law indices on 1-35 GHz given by this study vary around 1.74-1.87, which is consistent with earlier statistics in different solar cycles and very close to the simulations of the avalanche model by Lu.

Song Qiwu; Huang Guangli [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Tan Baolin, E-mail: songqw@pmo.ac.cn, E-mail: glhuang@pmo.ac.cn, E-mail: bltan@bao.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2012-05-10

484

A novel scaling law relating the geometrical dimensions of a photocathode radio frequency gun to its radio frequency properties.  

PubMed

Developing a photocathode RF gun with the desired RF properties of the ?-mode, such as field balance (e(b)) ~1, resonant frequency f(?) = 2856 MHz, and waveguide-to-cavity coupling coefficient ?(?) ~1, requires precise tuning of the resonant frequencies of the independent full- and half-cells (f(f) and f(h)), and of the waveguide-to-full-cell coupling coefficient (?(f)). While contemporary electromagnetic codes and precision machining capability have made it possible to design and tune independent cells of a photocathode RF gun for desired RF properties, thereby eliminating the need for tuning, access to such computational resources and quality of machining is not very widespread. Therefore, many such structures require tuning after machining by employing conventional tuning techniques that are iterative in nature. Any procedure that improves understanding of the tuning process and consequently reduces the number of iterations and the associated risks in tuning a photocathode gun would, therefore, be useful. In this paper, we discuss a method devised by us to tune a photocathode RF gun for desired RF properties under operating conditions. We develop and employ a simple scaling law that accounts for inter-dependence between frequency of independent cells and waveguide-to-cavity coupling coefficient, and the effect of brazing clearance for joining of the two cells. The method has been employed to successfully develop multiple 1.6 cell BNL?SLAC/UCLA type S-band photocathode RF guns with the desired RF properties, without the need to tune them by a tiresome cut-and-measure process. Our analysis also provides a physical insight into how the geometrical dimensions affect the RF properties of the photo-cathode RF gun. PMID:22225212

Lal, Shankar; Pant, K K; Krishnagopal, S

2011-12-01

485

Concept for a lunar array for very low frequency radio astronomy  

NASA Technical Reports Server (NTRS)

We discuss the design considerations relevant to a very low frequency array, to be deployed on the lunar near side during an early expedition. Such an array would operate in the frequency range 1-10 MHz, and would consist nominally of 20 antennas distributed over a region approximately 40 km in extent. Each antenna station would consist of a crossed-dipole antenna, together with a receiver, digitizer, solar cells, and batteries. In addition, the station will contain a UHF transmitter for relaying the digitized signal to a central station where it will be transmitted to Earth for subsequent processing, including cross-correlation with signals from other antennas. Each antenna station (including the central station) would be deployed as a self-contained unit, mounted on a miniature robotic vehicle. No fixed structures are required for the array.

Marsh, Kenneth A.; Mahoney, Michael J.; Kuiper, Thomas B. H.; Jones, Dayton L.

1992-01-01

486

Radio-frequency detection of electron oscillations in ultracold plasmas  

NASA Astrophysics Data System (ADS)

Electron oscillations in ultracold plasmas were previously observed through the enhanced electron emission from the plasma due to resonant rf heating. Both simple Langmuir and Tonks-Dattner resonances were detected in this manner. Recent theoretical work [1] predicts that the resonant energy absorption occurs primarily at the edge of the electron distribution and thus the resonant frequency depends on the charge imbalance of the plasma. To aid in investigating this claim, we have developed a new technique to observe electron resonances by directly monitoring the amplitude and phase changes of the rf field capacitively coupled onto a grid located near the plasma. This technique provides a direct measure of the rf absorption that does not depend on the dynamics of electron evaporation, and can be used in experiments where electron detection is not possible. In addition to studying Langmuir waves, we have also excited and observed an upper hybrid oscillation of the electrons in the presence of a perpendicular magnetic field.[4pt] [1] A. Lyubonko, T. Pohl, and J.-M. Rost, arXiv:1011.5937 (2010). Supported by NSF PHY-1004242.

Twedt, K. A.; Rolston, S. L.

2011-06-01

487

The NASA data systems standardization program - Radio frequency and modulation  

NASA Technical Reports Server (NTRS)

The modifications being considered by the NASA-ESA Working Group (NEWG) for space-data-systems standardization to maximize the commonality of the NASA and ESA RF and modulation systems linking spaceborne scientific experiments with ground stations are summarized. The first phase of the NEWG project shows that the NASA MK-IVA Deep Space Network and Shuttle Interrogator (SI) systems in place or planned for 1985 are generally compatible with the ESA Network, but that communications involving the Tracking and Data Relay Satellite (TDRS) are incompatible due to its use of spread-spectrum modulation, pseudonoise ranging, multiple-access channels, and Mbit/s data rates. Topics under study for the post-1985 period include low-bit-rate capability for the ESA Network, an optional 8-kHz command subcarrier for the SI, fixing the spacecraft-transponder frequency-multiplication ratios for possible X-band uplinks or X-band nondeep-space downlinks, review of incompatible TDRS features, and development of the 32-GHz band.

Martin, W. L.

1983-01-01

488

FIRST SPECTROSCOPIC IMAGING OBSERVATIONS OF THE SUN AT LOW RADIO FREQUENCIES WITH THE MURCHISON WIDEFIELD ARRAY PROTOTYPE  

SciTech Connect

We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array, observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9- 201.6 MHz. Though our observing period is characterized as a period of 'low' to 'medium' activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early glimpse of the nature of radio observations that will become available as the next generation of low-frequency radio interferometers come online over the next few years.

Oberoi, Divya; Matthews, Lynn D.; Lonsdale, Colin J.; Benkevitch, Leonid [MIT Haystack Observatory, Westford, MA (United States); Cairns, Iver H.; Lobzin, Vasili [School of Physics, University of Sydney, Sydney (Australia); Emrich, David; Wayth, Randall B.; Arcus, Wayne [Curtin Institute for Radio Astronomy, Curtin University, Perth (Australia); Morgan, Edward H.; Williams, Christopher [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA (United States); Prabu, T.; Vedantham, Harish [Raman Research Institute, Bangalore (India); Williams, Andrew [Perth Observatory, The University of Western Australia, Perth (Australia); White, Stephen M. [Air Force Research Laboratory, Kirtland, NM (United States); Allen, G. [CSIRO Astronomy and Space Science, Epping, NSW (Australia); Barnes, David [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne (Australia); Bernardi, Gianni [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Bowman, Judd D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Briggs, Frank H. [Research School of Astronomy and Astrophysics, The Australian National University, Canberra (Australia)

2011-02-20

489

47 CFR 74.461 - Transmitter power.  

Code of Federal Regulations, 2014 CFR

...COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup...or any other impedance-matched, radio frequency load. For the purpose...

2014-10-01

490

47 CFR 74.461 - Transmitter power.  

Code of Federal Regulations, 2011 CFR

...COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup...or any other impedance-matched, radio frequency load. For the purpose...

2011-10-01

491

47 CFR 74.461 - Transmitter power.  

Code of Federal Regulations, 2013 CFR

...COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Remote Pickup...or any other impedance-matched, radio frequency load. For the purpose...

2013-10-01

492

USING INTERNAL RADIO TRANSMITTERS TO DETERMINE THE BEHAVIORAL RESPONSE OF BULLFROGS, RANA CATESBEIANA, TO SEASONAL POND DRYING IN THE WILLAMETTE VALLEY, OREGON  

EPA Science Inventory

We implanted radio tags in adult bullfrogs from three ponds located in a Willamette Valley game reserve to determine their behavior and habitat use as the ponds dried during late summer. We used radio telemetry and a Global Position System (GPS) to locate and record the position ...