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Sample records for hf whip antennas

  1. Utilization of antenna arrays in HF systems

    Directory of Open Access Journals (Sweden)

    Louis Bertel

    2009-06-01

    Full Text Available

    Different applications of radio systems are based on the implementation of antenna arrays. Classically, radio direction

    finding operates with a multi channel receiving system connected to an array of receiving antennas. More

    recently, MIMO architectures have been proposed to increase the capacity of radio links by the use of antenna

    arrays at both the transmitter and receiver.

    The first part of this paper describes some novel experimental work carried out to examine the feasibility of applying

    MIMO techniques for communications within the HF radio band. A detailed correlation analysis of a variety

    of different antenna array configurations is presented. The second section of the paper also deals with HF

    MIMO communications, focusing on the problem from a modelling point of view. The third part presents a sensitivity

    analysis of different antenna array structures for HF direction finding applications. The results demonstrate

    that when modelling errors, heterogeneous antenna arrays are more robust in comparison to homogeneous structures


  2. Whipping Procrastination

    Science.gov (United States)

    2016-03-01

    53 Defense AT&L: March-April 2016 Whipping Procrastination Roy Wood, Ph.D. Wood is the acting Vice President of the Defense Acquisition University...written this article earlier, except I was procrastinating . This happens to me a lot, which is surprising since many consider me to be fairly productive. I... procrastinating . Chunk the work: I break big tasks down into smaller ones that are not quite so intimidating. Some people get really so- phisticated and use

  3. Characterization of inkjet-printing HF and UHF antennas for RFID applications

    Science.gov (United States)

    Tarapata, Grzegorz; Paczesny, Daniel; Kawecki, Krzysztof

    2013-10-01

    The aim of this work was to perform a set of RFID antennas on flexible plastic substrates designed for range of HF and UHF band. The samples was fabricated using inkjet printing technology and conductive material base on silver nanopartilces ink. Fabricated antennas have been characterized, and the results were compared with the parameters of antennas made with usage of classical PCB technology on FR4 laminate with copper metallization. The paper presents studies on the impact of elastic substrates and conductive materials on antennas electrical parameters, as well as the communication range of the resulting RFID tags. During the experiment two patterns of HF and three patterns of UHF antennas was examined and the antennas was realized on different types of substrates, such as PET, Kapton® and FR4.

  4. Modeling an HF NVIS Towel-Bar Antenna on a Coast Guard Patrol Boat. A Comparison of WIPL-D and the Numerical Electromagnetics Code (NEC)

    National Research Council Canada - National Science Library

    Mora, Darla; Weiser, Christopher; McKaughan, Michael

    2005-01-01

    A Coast Guard patrol boat high-frequency (HF) near-vertical incident skywave (NVIS) antenna is selected as a test case to compare the electromagnetic modeling programs Numerical Electromagnetics Code, NEC and WIPL-D code...

  5. Low-Profile Multiband and Flush-Mountable Wideband Antennas for HF/VHF and K/Ka Band Applications

    Science.gov (United States)

    Garrido Lopez, David

    This thesis introduces several novel antenna systems with extended performance capabilities achieved by either enabling multiple operation bands or by widening the bandwidth. Proposed theoretical concepts are successfully tested through simulations and experiments with excellent agreement are demonstrated. The designs developed in this thesis research are low-profile or flush mountable, enabling simple platform integration. In the HF/VHF bands, the development of a novel low-profile multiband antenna for vehicular applications is presented. Specifically, an inverted-F antenna is used as a driven element, to operate at the lowest frequency of 27 MHz, whereas two parasitic elements are built as inverted-L monopoles to enable resonances at 49 and 53 MHz. To eliminate the need for an external matching network, an offset feeding technique is used. When the antenna is mounted on a vehicle and bent to follow its profile, a very low-profile is achieved (lambda/44) while good impedance and far-field performance are maintained across all three bands. The developed antenna system is not only electrically smallest among others found in the literature, but it is easily modified for other band selections and tuning of each band can be readily achieved. Vehicular antennas are often used for high power applications, which may cause exposure of nearby individuals to possibly dangerous electromagnetic fields. To assess this hazard, the RF exposure of a vehicle's crew is discussed and an original and fast modeling approach for prediction thereof is demonstrated. The modeling approach is based on eigenmode analysis for acquiring a range of frequencies where the shielding effectiveness of a vehicle cabin is expected to be lower than average. This approach is typically much faster and requires less computational resources as compared to classical full-wave analyses. This analysis also shows that the position of an antenna system is critical and must be considered when high-power RF

  6. Application of small-size antennas for estimation of angles of arrival of HF signals scattered by ionospheric irregularities

    Science.gov (United States)

    Guo, Qiang; Galushko, Volodymyr G.; Zalizovski, Andriy V.; Kashcheyev, Sergiy B.; Zheng, Yu

    2018-05-01

    A modification of the Doppler Interferometry Technique is suggested to enable estimating angles of arrival of comparatively broadband HF signals scattered by random irregularities of the ionospheric plasma with the use of small-size weakly directional antennas. The technique is based on the measurements of cross-spectra phases of the probe radiation recorded at least in three spatially separated points. The developed algorithm has been used to investigate the angular and frequency-time characteristics of HF signals propagating at frequencies above the maximum usable one (MUF) for the direct radio path Moscow-Kharkiv. The received signal spectra show presence of three families of spatial components attributed, respectively, to scattering by plasma irregularities near the middle point of the radio path, ground backscatter signals and scattering of the sounding signals by the intense plasma turbulence associated with auroral activations. It has been shown that the regions responsible for the formation of the third family components are located well inside the auroral oval. The drift velocity and direction of the auroral ionosphere plasma have been determined. The obtained estimates are consistent with the classical conception of the ionospheric plasma convection at high latitudes and do not contradict the results of investigations of the auroral ionosphere dynamics using the SuperDARN network.

  7. HF Meander-Line Antenna Simulations and Investigations for NVIS on a HMMV

    Science.gov (United States)

    2016-09-28

    Hong   Kong ,  2011,  pp.  194-­‐197.     [3]C.  C.  Lin,  S.  W.  Kuo  and  H.  R...ideal  radiation   conditions  for  the   simulated  antenna.  The  simulated  gain  pattern  in  figure  2  shows  a...meters.     Future   Work     Reducing  the  coupling  between  the  radiating  elements  of

  8. Antennas.

    Science.gov (United States)

    1982-03-03

    arc csch csch - 1 Russian English rot curl lg log !i FIVE-METER SPHERICAL MILLIMETER-BAND ANTENNA P.M. Geruni This article presents the basic...rlpe’ I operating band, MHz elliptical Xk, mm X , m fk, MHz z wavgudeeg MHz f =1.2f f =0.95f waegid H X B rip = E40 104.5 56.4 2872 5410 3446 5141 E48...aperture In order to do this, we expand (30) into a series with respect to y. Limiting ourselves to the first three terms of the expansion, we obtain r

  9. A novel method for the evaluation of polarization and hemisphere coverage of HF radio noise measurement antennas

    NARCIS (Netherlands)

    Witvliet, Ben A.; van Maanen, Erik; Bentum, Mark J.; Slump, Cornelis H.; Schiphorst, Roel

    2015-01-01

    In HF (3-30 MHz) communications the ambient electromagnetic background noise or 'radio noise' generally is the limiting factor in reception. Radio noise measurements are needed for spectrum pollution control and to provide reference levels for radio system design. This article discusses the

  10. Flogging tired horses: Who wants whipping and who would walk away if whipping horses were withheld?

    Science.gov (United States)

    Griffiths, Mark D.; Ascione, Frank R.; Wilson, Bethany

    2018-01-01

    Recent studies have cast doubt on the effectiveness of whipping horses during races and this has led to questions concerning its continuing justification. Furthermore, it has been argued that whipping tired horses in racing is the most televised form of violence to animals. The present study used de-identified data from a recent independent Australian poll (n = 1,533) to characterise the 26% of respondents (113 females and 271 males) who support the whipping of racehorses and the 10% of racing enthusiasts in the sample (44 females and 63 males) who would stop watching races and betting on them if whipping were banned. Logistic regression models examining associations between age, gender, and income level of respondents demonstrated that those who support racehorse whipping are significantly more likely to be male. Among racing enthusiasts who would stop watching races and betting on them if whipping were banned, those in the lowest income bracket were over-represented. The more frequently respondents attended races or gambled on them, the more likely they were to agree that horses should be hit with a whip during the normal course of a race. These findings align with previous studies of violence among men and women but may also be attributed to male support of traditional gambling practices. Globally, racing organisations may consider the findings of the present study helpful in their deliberations on the merits of continuing the practice of whipping tired horses in the name of sport. The study might also provide important data for stakeholders who demand that it continues. PMID:29466458

  11. Flogging tired horses: Who wants whipping and who would walk away if whipping horses were withheld?

    Science.gov (United States)

    McGreevy, Paul D; Griffiths, Mark D; Ascione, Frank R; Wilson, Bethany

    2018-01-01

    Recent studies have cast doubt on the effectiveness of whipping horses during races and this has led to questions concerning its continuing justification. Furthermore, it has been argued that whipping tired horses in racing is the most televised form of violence to animals. The present study used de-identified data from a recent independent Australian poll (n = 1,533) to characterise the 26% of respondents (113 females and 271 males) who support the whipping of racehorses and the 10% of racing enthusiasts in the sample (44 females and 63 males) who would stop watching races and betting on them if whipping were banned. Logistic regression models examining associations between age, gender, and income level of respondents demonstrated that those who support racehorse whipping are significantly more likely to be male. Among racing enthusiasts who would stop watching races and betting on them if whipping were banned, those in the lowest income bracket were over-represented. The more frequently respondents attended races or gambled on them, the more likely they were to agree that horses should be hit with a whip during the normal course of a race. These findings align with previous studies of violence among men and women but may also be attributed to male support of traditional gambling practices. Globally, racing organisations may consider the findings of the present study helpful in their deliberations on the merits of continuing the practice of whipping tired horses in the name of sport. The study might also provide important data for stakeholders who demand that it continues.

  12. Flogging tired horses: Who wants whipping and who would walk away if whipping horses were withheld?

    Directory of Open Access Journals (Sweden)

    Paul D McGreevy

    Full Text Available Recent studies have cast doubt on the effectiveness of whipping horses during races and this has led to questions concerning its continuing justification. Furthermore, it has been argued that whipping tired horses in racing is the most televised form of violence to animals. The present study used de-identified data from a recent independent Australian poll (n = 1,533 to characterise the 26% of respondents (113 females and 271 males who support the whipping of racehorses and the 10% of racing enthusiasts in the sample (44 females and 63 males who would stop watching races and betting on them if whipping were banned. Logistic regression models examining associations between age, gender, and income level of respondents demonstrated that those who support racehorse whipping are significantly more likely to be male. Among racing enthusiasts who would stop watching races and betting on them if whipping were banned, those in the lowest income bracket were over-represented. The more frequently respondents attended races or gambled on them, the more likely they were to agree that horses should be hit with a whip during the normal course of a race. These findings align with previous studies of violence among men and women but may also be attributed to male support of traditional gambling practices. Globally, racing organisations may consider the findings of the present study helpful in their deliberations on the merits of continuing the practice of whipping tired horses in the name of sport. The study might also provide important data for stakeholders who demand that it continues.

  13. Equipment: Antenna systems

    Science.gov (United States)

    Petrie, L. E.

    1986-03-01

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

  14. Pipe whip analysis using the TEDEL code

    International Nuclear Information System (INIS)

    Millard, D.; Hoffmann, A.

    1985-02-01

    In view of their abundance, piping systems are one of the main components in power industries and in particular in nuclear power plants. They must be designed for normal as well as faulted conditions, for safety requirements. The prediction of the dynamic behaviour of the free pipe requires accounting for several nonlinearities. For this purpose, a beam type finite element program (TEDEL) has been used. The aim of this paper is to enlight the main features of this program, when applied to pipe whip analysis. An example of application to a real case will also be presented

  15. Comparative study of computational model for pipe whip analysis

    International Nuclear Information System (INIS)

    Koh, Sugoong; Lee, Young-Shin

    1993-01-01

    Many types of pipe whip restraints are installed to protect the structural components from the anticipated pipe whip phenomena of high energy lines in nuclear power plants. It is necessary to investigate these phenomena accurately in order to evaluate the acceptability of the pipe whip restraint design. Various research programs have been conducted in many countries to develop analytical methods and to verify the validity of the methods. In this study, various calculational models in ANSYS code and in ADLPIPE code, the general purpose finite element computer programs, were used to simulate the postulated pipe whips to obtain impact loads and the calculated results were compared with the specific experimental results from the sample pipe whip test for the U-shaped pipe whip restraints. Some calculational models, having the spring element between the pipe whip restraint and the pipe line, give reasonably good transient responses of the restraint forces compared with the experimental results, and could be useful in evaluating the acceptability of the pipe whip restraint design. (author)

  16. The phylogeny of fossil whip spiders.

    Science.gov (United States)

    Garwood, Russell J; Dunlop, Jason A; Knecht, Brian J; Hegna, Thomas A

    2017-04-21

    Arachnids are a highly successful group of land-dwelling arthropods. They are major contributors to modern terrestrial ecosystems, and have a deep evolutionary history. Whip spiders (Arachnida, Amblypygi), are one of the smaller arachnid orders with ca. 190 living species. Here we restudy one of the oldest fossil representatives of the group, Graeophonus anglicus Pocock, 1911 from the Late Carboniferous (Duckmantian, ca. 315 Ma) British Middle Coal Measures of the West Midlands, UK. Using X-ray microtomography, our principal aim was to resolve details of the limbs and mouthparts which would allow us to test whether this fossil belongs in the extant, relict family Paracharontidae; represented today by a single, blind species Paracharon caecus Hansen, 1921. Tomography reveals several novel and significant character states for G. anglicus; most notably in the chelicerae, pedipalps and walking legs. These allowed it to be scored into a phylogenetic analysis together with the recently described Paracharonopsis cambayensis Engel & Grimaldi, 2014 from the Eocene (ca. 52 Ma) Cambay amber, and Kronocharon prendinii Engel & Grimaldi, 2014 from Cretaceous (ca. 99 Ma) Burmese amber. We recovered relationships of the form ((Graeophonus (Paracharonopsis + Paracharon)) + (Charinus (Stygophrynus (Kronocharon (Charon (Musicodamon + Paraphrynus)))))). This tree largely reflects Peter Weygoldt's 1996 classification with its basic split into Paleoamblypygi and Euamblypygi lineages; we were able to score several of his characters for the first time in fossils. Our analysis draws into question the monophyly of the family Charontidae. Our data suggest that Graeophonus is a crown group amblypygid, and falls within a monophyletic Paleoamblypgi clade, but outside the family Paracharontidae (= Paracharonopsis + Paracharon). Our results also suggest a new placement for the Burmese amber genus Kronocharon, a node further down from its original position. Overall, we offer a

  17. RNAseq Transcriptional Profiling following Whip Development in Sugarcane Smut Disease.

    Directory of Open Access Journals (Sweden)

    Patricia D C Schaker

    Full Text Available Sugarcane smut disease is caused by the biotrophic fungus Sporisorium scitamineum. The disease is characterized by the development of a whip-like structure from the primary meristems, where billions of teliospores are produced. Sugarcane smut also causes tillering and low sucrose and high fiber contents, reducing cane productivity. We investigated the biological events contributing to disease symptoms in a smut intermediate-resistant sugarcane genotype by examining the transcriptional profiles (RNAseq shortly after inoculating the plants and immediately after whip emission. The overall picture of disease progression suggests that premature transcriptional reprogramming of the shoot meristem functions continues until the emergence of the whip. The guidance of this altered pattern is potentially primarily related to auxin mobilization in addition to the involvement of other hormonal imbalances. The consequences associated with whip emission are the modulation of typical meristematic functions toward reproductive organ differentiation, requiring strong changes in carbon partitioning and energy production. These changes include the overexpression of genes coding for invertases and trehalose-6P synthase, as well as other enzymes from key metabolic pathways, such as from lignin biosynthesis. This is the first report describing changes in the transcriptional profiles following whip development, providing a hypothetical model and candidate genes to further study sugarcane smut disease progression.

  18. Nonlinear dynamic analysis of high energy line pipe whip

    International Nuclear Information System (INIS)

    Hsu, L.C.; Kuo, A.Y.; Tang, H.T.

    1983-01-01

    To facilitate potential cost savings in pipe whip protection design, TVA conducted a 1'' high pressure line break test to investigate the pipe whip behavior. The test results are available to EPRI as a data base for a generic study on nonlinear dynamic behavior of piping systems and pipe whip phenomena. This paper describes a nonlinear dynamic analysis of the TVA high energy line tests using ABAQUS-EPGEN code. The analysis considers the effects of large deformation and high strain rate on resisting moment and energy absorption capability of the analyzed piping system. The numerical results of impact forces, impact velocities, and reaction forces at pipe supports are compared to the TVA test data. The pipe whip impact time and forces have also been calculated per the current NRC guidelines and compared. The calculated pipe support reaction forces prior to impact have been found to be in good agreement with the TVA test data except for some peak values at the very beginning of the pipe break. These peaks are believed to be due to stress wave propagation which cannot be addressed by the ABAQUS code. Both the effects of elbow crushing and strain rate have been approximately simulated. The results are found to be important on pipe whip impact evaluation. (orig.)

  19. RNAseq Transcriptional Profiling following Whip Development in Sugarcane Smut Disease

    Science.gov (United States)

    Taniguti, Lucas M.; Peters, Leila P.; Creste, Silvana; Aitken, Karen S.; Van Sluys, Marie-Anne; Kitajima, João P.; Vieira, Maria L. C.; Monteiro-Vitorello, Claudia B.

    2016-01-01

    Sugarcane smut disease is caused by the biotrophic fungus Sporisorium scitamineum. The disease is characterized by the development of a whip-like structure from the primary meristems, where billions of teliospores are produced. Sugarcane smut also causes tillering and low sucrose and high fiber contents, reducing cane productivity. We investigated the biological events contributing to disease symptoms in a smut intermediate-resistant sugarcane genotype by examining the transcriptional profiles (RNAseq) shortly after inoculating the plants and immediately after whip emission. The overall picture of disease progression suggests that premature transcriptional reprogramming of the shoot meristem functions continues until the emergence of the whip. The guidance of this altered pattern is potentially primarily related to auxin mobilization in addition to the involvement of other hormonal imbalances. The consequences associated with whip emission are the modulation of typical meristematic functions toward reproductive organ differentiation, requiring strong changes in carbon partitioning and energy production. These changes include the overexpression of genes coding for invertases and trehalose-6P synthase, as well as other enzymes from key metabolic pathways, such as from lignin biosynthesis. This is the first report describing changes in the transcriptional profiles following whip development, providing a hypothetical model and candidate genes to further study sugarcane smut disease progression. PMID:27583836

  20. Plasma antennas: dynamically configurable antennas for communications

    International Nuclear Information System (INIS)

    Borg, G.; Harris, J.

    1999-01-01

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

  1. Design for whipping pipe impact on reinforced concrete panels

    International Nuclear Information System (INIS)

    Chen, C.C.; Gurbuz, O.

    1984-01-01

    This paper describes determination of local and overall effects on reinforced concrete panels due to whipping pipe impact in postulated pipe break events. Local damage includes the prediction of minimum concrete panel thickness required to prevent spalling from the back face of the target reinforced concrete panels. Evaluation of overall effect deals with the ductility ratio calculation for the target reinforced concrete panels. Design curves for determining the minimum panel thickness and the minimum reinforcement of reinforced concrete panels are presented in this paper for some cases commonly encountered in nuclear applications. The methodology and the results provided can be used to determine if an existing reinforced concrete wall is capable of resisting the whipping pipe impact, and consequently, if pipe whip restraints can be eliminated

  2. Calorie reduction of chocolate ganache through substitution of whipped cream

    Directory of Open Access Journals (Sweden)

    Yu Jin Kim

    2017-03-01

    Full Text Available Chocolate has been around for 3,000 years and is loved by many people for as long as its history. However, chocolate is classified as a high calorie food due to the high fat and sugar contents. These contents have negative effects on health, such as obesity, so some people have concerns about chocolate. Nevertheless, it has attracted more attention recently due to functional ingredients such as polyphenols and flavonoids of cacao, which is a main component of chocolate. This study was conducted to reduce the fat content in chocolate, which is the biggest disadvantage of chocolate. We investigated the physicochemical properties of different kinds of chocolate ganache made of whipped cream, milk, vegetable cream, and coconut milk. The whipped cream chocolate ganache was considered as the control group. The added ingredients affected moisture, crude fat, sugar contents, hardness, and influenced every result of the tests performed. The whipped cream chocolate ganache with the lowest moisture and highest fat contents showed the same result (the lowest moisture contents and highest fat contents; p < 0.05 and resulted in average hardness. The vegetable cream chocolate ganache showed similar results to that of the whipped cream’s result above, except in the category of hardness. The vegetable cream chocolate ganache showed a high circumference, height, and hardness. Milk chocolate, with the highest moisture and lowest fat content, showed identical results with the whipped cream’s result. In circumference, height and hardness, milk chocolate ganache showed the highest circumference (p < 0.05, a low height, and a similar value to whipped cream, but coconut milk also showed low values of circumferences and hardness. Overall, the whipped cream chocolate ganache was the most preferred chocolate in the sensory test, but the coconut milk chocolate ganache was the softest chocolate among the cream replacements. Because of its low caloric content and

  3. Reliability analysis of pipe whip impacts

    International Nuclear Information System (INIS)

    Alzbutas, R.; Dundulis, G.; Kulak, R.F.; Marchertas, P.V.

    2003-01-01

    A probabilistic analysis of a group distribution header (GDH) guillotine break and the damage resulting from the failed GDH impacting against a neighbouring wall was carried out for the Ignalita RBMK-1500 reactor. The NEPTUNE software system was used for the deterministic transient analysis of a GDH guillotine break. Many deterministic analyses were performed using different values of the random variables that were specified by ProFES software. All the deterministic results were transferred to the ProFES system, which then performed probabilistic analyses of piping failure and wall damage. The Monte Carlo Simulation (MCS) method was used to study the sensitivity of the response variables and the effect of uncertainties of material properties and geometry parameters to the probability of limit states. The First Order Reliability Method (FORM) was used to study the probability of failure of the impacted-wall and the support-wall. The Response Surface (RS/MCS) method was used in order to express failure probability as function and to investigate the dependence between impact load and failure probability. The results of the probability analyses for a whipping GDH impacting onto an adjacent wall show that: (i) there is a 0.982 probability that after a GDH guillotine break contact between GDH and wall will occur; (ii) there is a probability of 0.013 that the ultimate tensile strength of concrete at the impact location will be reached, and a through-crack may open; (iii) there is a probability of 0.0126 that the ultimate compressive strength of concrete at the GDH support location will be reached, and the concrete may fail; (iv) at the impact location in the adjacent wall, there is a probability of 0.327 that the ultimate tensile strength of the rebars in the first layer will be reached and the rebars will fail; (v) at the GDH support location, there is a probability of 0.11 that the ultimate stress of the rebars in the first layer will be reached and the rebars will fail

  4. An investigation of racing performance and whip use by jockeys in thoroughbred races.

    Directory of Open Access Journals (Sweden)

    David Evans

    Full Text Available Concerns have been expressed concerning animal-welfare issues associated with whip use during Thoroughbred races. However, there have been no studies of relationships between performance and use of whips in Thoroughbred racing. Our aim was to describe whip use and the horses' performance during races, and to investigate associations between whip use and racing performance. Under the Australian Racing Board (ARB rules, only horses that are in contention can be whipped, so we expected that whippings would be associated with superior performance, and those superior performances would be explained by an effect of whipping on horse velocities in the final 400 m of the race. We were also interested to determine whether performance in the latter sections of a race was associated with performance in the earlier sections of a race. Measurements of whip strikes and sectional times during each of the final three 200 metre (m sections of five races were analysed. Jockeys in more advanced placings at the final 400 and 200 m positions in the races whipped their horses more frequently. Horses, on average, achieved highest speeds in the 600 to 400 m section when there was no whip use, and the increased whip use was most frequent in the final two 200 m sections when horses were fatigued. This increased whip use was not associated with significant variation in velocity as a predictor of superior placing at the finish.

  5. Studies on the Whipping Characteristics and Yield of Dehydrated ...

    African Journals Online (AJOL)

    The objective of this research was to evaluate the yield and whipping characteristics of dehydrated egg so as to establish the optimum conditions for commercial applications of powdered egg. Eggs were cracked, separated into their components by gravity. Each of the egg components (egg yolk, albumin, whole liquid egg) ...

  6. HF laser

    International Nuclear Information System (INIS)

    Suzuki, Kazuya; Iwasaki, Matae

    1977-01-01

    A review is made of the research and development of HF chemical laser and its related work. Many gaseous compounds are used as laser media successfully; reaction kinetics and technological problems are described. The hybrid chemical laser of HF-CO 2 system and the topics related to the isotope separation are also included. (auth.)

  7. First measurements of the neutrals pressure and of the degassing level of the lower hybrid antenna induced by the HF power

    International Nuclear Information System (INIS)

    Goniche, M.; Berger-By, G.; Bibet, P.; Bonnel, P.; Bruneau, J.L.; Capitain, J.J.; Gil, C.; Hertout, P.; Rodriguez, L.; Magne, R.

    1989-12-01

    Previous experiments have shown that large amounts of gas may be desorbed from the waveguides walls of a lower hybrid antenna. To reduce the pressure rise, a getter pump has been connected to the LH vessel of Tore Supra. The effective neutrals pumping speed of the LH launcher during a plasma shot has been measured for different configurations of the getter pump (inactive, low conductance and high conductance duct). For deuterium, an effective pumping speed of 33 m 3 /s was obtained. During short conditioning pulses and 2-s plasma shots, degassing rates were measured for RF power level up to 1.2 MW. With different filling gas (He, H 2 , D 2 ), degassing rates are documented and effects of conditioning are discussed. This neutrals influx contributes to the particles balance of the plasma discharge: a significant increase of the total number of particles (10-20%) and a flattening of the density profile are inferred. Large increase of the neutrals pressure in the pumped limitor (up to 32%) was also observed. For 2-s shots, this pressure rise was held below 3 mPa at an average LH power density of 1.5 kW/cm 2 . However, this pressure rise may be, to some extent, larger in the reduced-section part of the launcher which has a low conductance. It is expected that this pressure rise should not exceed 5 mPa at full power (5 KW/cm 2 ) after conditioning [fr

  8. Study of pipe-whip parameters in pipelines

    International Nuclear Information System (INIS)

    Guerreiro, J.N.C.; Loula, A.F.D.; Galeao, A.C.N.R.

    1980-01-01

    The problem of the high energy pipe-whip, assuming an elastic-plastic behavior for the tube material and taking in account the internal pressure, is studied. The constraints are simulated as bilinear springs and viscous dampers. A general research, based on the finite element method was developed to analyse the phenomenon. The influence of the following parameters: gap, damping coefficient, stiffness, constraints positioning and internal pressure of the tube is studied. (Author) [pt

  9. Whip use by jockeys in a sample of Australian Thoroughbred races--an observational study.

    Directory of Open Access Journals (Sweden)

    Paul D McGreevy

    Full Text Available The use of whips by jockeys is an issue. The current study viewed opportunistic high-speed footage of 15 race finishes frame-by-frame to examine the outcomes of arm and wrist actions (n = 350 on 40 horses viewed from the left of the field. Any actions fully or partially obscured by infrastructure or other horses were removed from the database, leaving a total of 104 non-contact sweeps and 134 strikes. For all instances of arm actions that resulted in fully visible whip strikes behind the saddle (n = 109, the outcomes noted were area struck, percentage of unpadded section making contact, whether the seam made contact and whether a visible indentation was evident on impact. We also recorded use of clockwise or counter-clockwise arm action from each jockey's whip, whether the whip was held like a tennis racquet or a ski pole, whether the hind leg on the side of the impact was in stance or swing phase and whether the jockey's arm was seen traveling above shoulder height. The goal of the study was to characterize the area struck and the visual impact of whip use at the level of the horse. We measured the ways in which both padded and unpadded sections of the whip made impact. There was evidence of at least 28 examples, in 9 horses, of breaches of the whip rules (one seam contact, 13 contacts with the head, and 14 arm actions that rose above the height of the shoulder. The whip caused a visible indentation on 83% of impacts. The unpadded section of the whip made contact on 64% of impacts. The results call into question the ability of Stewards to effectively police the rules concerning whip use and, more importantly, challenge the notion that padding the distal section of whips completely safeguards horses from any possible whip-related pain.

  10. Experimental investigations of higher-order springing and whipping-WILS project

    Directory of Open Access Journals (Sweden)

    Hong Sa Young

    2014-12-01

    Full Text Available Springing and whipping are becoming increasingly important considerations in ship design as container ships increase in size. In this study, the springing and whipping characteristics of a large container ship were investigated through a series of systematic model tests in waves. A multi-segmented hull model with a backbone was adopted for measurement of springing and whipping signals. A conversion method for extracting torsion springing and whipping is described in this paper for the case of an open-section backbone. Higher-order springing, higher-mode torsion responses, and the effects of linear and nonlinear springing in irregular waves are highlighted in the discussion.

  11. Radio antennas

    Science.gov (United States)

    Gibson, S. W.

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

  12. Abnormal vibration of turbine due to oil whip

    International Nuclear Information System (INIS)

    Koo, Jae Raeyang; Hwang, Jae Hyeon

    2001-01-01

    Almost all rotating machinery has bearings. Bearing is one of the most important part of rotating machinery. Vibration of rotating machinery depend on its bearing conditions. Bearing conditions are following; oil gap, bearing type, bearing temperature, bearing oil condition. Especially, bearing oil condition influences on rotating machinery vibration directly. In this paper we have discussed the abnormal vibration of turbine due to oil condition. Oil whip problem was occurred in the certain power plant and we had solved this problem through the control of operating values and alignment

  13. A elastic-plastic model for pipe whip

    International Nuclear Information System (INIS)

    Maneschy, J.E.A.

    1980-04-01

    The dynamic behavior of a cantilever beam simulating a pipe after full rupture at a given cross-section is investigated. This problem, known as pipe whip, has to be analysed within the frame of plastic deformations. The physical model is represented by a cantilever, subjected to a step-load at the free end, and a support designed to absorb the maximum possible kinetic energy of the tube generated by suddenly applied force. The analysis is performed using the Bernoulli theory for straight beams, assuming for the moment-curvature relation a bi-linear law. (author)

  14. The measured contribution of whipping and springing on the fatigue and extreme loading of container vessels

    Science.gov (United States)

    Storhaug, Gaute

    2014-12-01

    Whipping/springing research started in the 50'ies. In the 60'ies inland water vessels design rules became stricter due to whipping/springing. The research during the 70-90'ies may be regarded as academic. In 2000 a large ore carrier was strengthened due to severe cracking from North Atlantic operation, and whipping/springing contributed to half of the fatigue damage. Measurement campaigns on blunt and slender vessels were initiated. A few blunt ships were designed to account for whipping/springing. Based on the measurements, the focus shifted from fatigue to extreme loading. In 2005 model tests of a 4,400 TEU container vessel included extreme whipping scenarios. In 2007 the 4400 TEU vessel MSC Napoli broke in two under similar conditions. In 2009 model tests of an 8,600 TEU container vessel container vessel included extreme whipping scenarios. In 2013 the 8,100 TEU vessel MOL COMFORT broke in two under similar conditions. Several classification societies have published voluntary guidelines, which have been used to include whipping/springing in the design of several container vessels. This paper covers results from model tests and full scale measurements used as background for the DNV Legacy guideline. Uncertainties are discussed and recommendations are given in order to obtain useful data. Whipping/springing is no longer academic.

  15. Hydro-elastic response of ship structures to slamming induced whipping

    NARCIS (Netherlands)

    Tuitman, J.T.

    2010-01-01

    Slamming induced whipping can significantly increase the structural loading of ships. Although this is well-known, the whipping contribution to the structural loading is rarely taken into account when computing the structural loading. An exception are the "dynamic loading" factors found in

  16. Conceptual design of pipe whip restraints using interactive computer analysis

    International Nuclear Information System (INIS)

    Rigamonti, G.; Dainora, J.

    1975-01-01

    Protection against pipe break effects necessitates a complex interaction between failure mode analysis, piping layout, and structural design. Many iterations are required to finalize structural designs and equipment arrangements. The magnitude of the pipe break loads transmitted by the pipe whip restraints to structural embedments precludes the application of conservative design margins. A simplified analytical formulation of the nonlinear dynamic problems associated with pipe whip has been developed and applied using interactive computer analysis techniques. In the dynamic analysis, the restraint and the associated portion of the piping system, are modeled using the finite element lumped mass approach to properly reflect the dynamic characteristics of the piping/restraint system. The analysis is performed as a series of piecewise linear increments. Each of these linear increments is terminated by either formation of plastic conditions or closing/opening of gaps. The stiffness matrix is modified to reflect the changed stiffness characteristics of the system and re-started using the previous boundary conditions. The formation of yield hinges are related to the plastic moment of the section and unloading paths are automatically considered. The conceptual design of the piping/restraint system is performed using interactive computer analysis. The application of the simplified analytical approach with interactive computer analysis results in an order of magnitude reduction in engineering time and computer cost. (Auth.)

  17. Pipe whip: a summary of the damage observed in BNL pipe-on-pipe impact tests

    International Nuclear Information System (INIS)

    Baum, M.R.

    1987-01-01

    This paper describes examples of the damage resulting from the impact of a whipping pipe on a nearby pressurised pipe. The work is a by-product of a study of the motion of a whipping pipe. The tests were conducted with small-diameter pipes mounted in rigid supports and hence the results are not directly applicable to large-scale plant applications where flexible support mountings are employed. The results illustrate the influence of whipping pipe energy, impact position and support type on the damage sustained by the target pipe. (author)

  18. Liver Trauma in the Kitchen: Preparing Whipped Cream with a Siphon Is Not without Risk

    Directory of Open Access Journals (Sweden)

    Jeremy Bourenne

    2015-01-01

    Full Text Available We report the case of a 36-year-old woman suffering from liver injury caused by the malfunction of a whipped cream siphon. When this patient handled the whipped cream siphon, the screwed metallic upper part of the siphon was suddenly dissociated from its base and came violently striking her right hypochondrium. At first, the severity of injury was underestimated. Subsequently, due to the persistence of pain experienced by the patient, an abdominal CT scan was performed. It highlighted a severe liver injury with rupture of a branch of the hepatic artery. The evolution was favorable after completion of an embolization and a secondary capsular rupture.

  19. Antenna toolkit

    CERN Document Server

    Carr, Joseph

    2006-01-01

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

  20. HF i dag

    DEFF Research Database (Denmark)

    Lindstrøm, Maria Duclos; Simonsen, Birgitte

    2008-01-01

    Notatet er lavet på baggrund af uddannelsesbiografiske dybdeinterviews med kursister på toårigt HF. Indenfor rammerne af en pilotundersøgelse identificerer notatet fire gennemgående profiler: De pragmatiske, de fagligt usikre, second chance-kursisterne, og de HF-kursister, som har HF som first...

  1. Emulsion droplet spreading at air/water interfaces: mechanisms and relevance to the whipping of cream

    NARCIS (Netherlands)

    Hotrum, N.E.

    2004-01-01

    Keywords:emulsion, spreading coefficient, surface tension, emulsifier, whipped cream, dairy foam, partial coalescence In this thesis, the interaction between emulsion droplets and expanding air/water interfaces was investigated. The

  2. Extrapolation of model tests measurements of whipping to identify the dimensioning sea states for container ships

    DEFF Research Database (Denmark)

    Storhaug, Gaute; Andersen, Ingrid Marie Vincent

    2015-01-01

    to small storms. Model tests of three container ships have been carried out in different sea states under realistic assumptions. Preliminary extrapolation of the measured data suggested that moderate storms are dimensioning when whipping is included due to higher maximum speed in moderate storms...

  3. DEVELOPMENT OF A FUNCTIONAL PURPOSE WHIPPED BREAD WHOLE GRAIN WHEAT, RYE AND WHEAT BRAN

    Directory of Open Access Journals (Sweden)

    G. O. Magomedov

    2015-01-01

    Full Text Available The article discusses the development of whipped bakery products enriched with dietary fiber, minerals, vitamins retinol, tocopherol, group, polyunsaturated fatty acids through the use of rye and wheat bran and flour of wholegrain wheat. The main raw material for enrichment whipped bakery products used wheat bran and rye. Choice of rye and wheat bran as supplementation prepared whipped bread is explained not only from the point of view of the rationality of the use of this secondary raw materials, but also its rich vitamin and mineral composition. Wheat bran contain the necessary man of b vitamins, including B1, B2, B6, PP and others. Found provitamin a (carotene and vitamin E (tocopherol. Bran is rich in mineral substances. Among them potassium, magnesium, chromium, zinc, copper, selenium and other trace elements. Thanks to this composition bran are essential dietary product. They are rich in insoluble fiber and can be useful to reduce the risk of developing colon cancer. Rye bran contain dietary fiber, tocopherol E, thiamin B1, Riboflavin B2, Pantothenic acid B5, B4 (choline, nicotinic acid B3, etc. In the bran rich set of microelements and macroelements such as iron, calcium, magnesium, phosphorus, potassium, zinc, iodine, selenium, chromium, etc. the Introduction in the diet, bran rye contribute to the prevention and treatment of atherosclerosis, diabetes and anemia. They restore blood pressure, reduce blood sugar levels and improve the cardiovascular system. Flour from wholegrain wheat is the main supplier of bread protein and starch, while preserving the maximum of the original nutritional value of the grain, enriched whipped bread macro - and micronutrients. The analysis of the chemical composition of flour from wholegrain wheat, rye and wheat bran leads to the conclusion that the choice of these types of materials suitable for making the recipe whipped bakery products, because their use can increase the content in bread is not only the

  4. A Perspective on the Numerical and Experimental Characteristics of Multi-Mode Dry-Friction Whip and Whirl

    National Research Council Canada - National Science Library

    Wilkes, Jason C

    2008-01-01

    .... Efforts of the author, Dyck [1], Pavalek [2], and coworkers enabled the design and construction of a test rig that demonstrated and recorded accurately the character of multi-mode dry-friction whip and whirl...

  5. Effects of ratio of milk fat to soy bean oil and whipping time on qualities of milk ice cream

    Directory of Open Access Journals (Sweden)

    Sukrit Thaiudom

    2007-01-01

    Full Text Available Qualities of ice cream are based on air cells, ice crystals and fat particles, which are the important parts to build up a good structure of ice cream. Ice cream whipping time also affects the ice cream qualities.This study focused on effects of ratio of milk fat to soy bean oil, whipping time, and their interaction on ice cream mix viscosity, overrun, air cell size, fat destabilization, hardness, melting rate, and shape retention ofice cream. Ice creams with ratio of milk fat to soy bean oil at 100:0, 50:50, 0:100 and whipping time at 15 and 20 min were produced and determined for their qualities. The results showed that ratio of milk fat to soybean oil affected all qualities of ice cream, while duration of whipping time influenced the overrun and air cell size. The interaction of ratio of milk fat to soy bean oil and whipping time affected only overrun. Ice creammix with ratio of milk fat to soy bean oil 100:0 showed the highest apparent viscosity and hardness and the biggest air cell size. Whipping time of ice cream for 20 min showed a bigger size of air cells than the whippingtime for 15 min (p < 0.05. These results can be applied to the manufacture of modified ice cream.

  6. A review of methods for analysing the whipping movement of pipework

    International Nuclear Information System (INIS)

    Nicholson, M.D.

    1977-11-01

    A postulated rupture of a pipe carrying high energy fluid results in large forces acting on the piping run due to the reactive forces of the escaping fluid. This can cause a large whipping movement of the pipe. It is necessary to design and position restraints to contain this motion, which, although it only occurs in the event of a low probability accident, may produce damage in systems essential for the safe shutdown of a nuclear reactor. Hence an understanding of the dynamic response of the piping and supports is required. A discussion is presented of the pipe whip problem and present methods of investigation are reviewed. In order to assess their applicability, some general methods of non-linear dynamics are surveyed. (author)

  7. Effects of the Hot Alignment of a Power Unit on Oil-Whip Instability Phenomena

    Directory of Open Access Journals (Sweden)

    A. Vania

    2010-01-01

    Full Text Available This paper shows the results of the analysis of the dynamic behaviour of a power unit, whose shaft-train alignment was significantly influenced by the machine thermal state, that was affected in operating condition by high subsynchronous vibrations caused by oil-whip instability phenomena. The dynamic stiffness coefficients of the oil-film journal bearings of the generator were evaluated considering the critical average journal positions that caused the instability onsets. By including these bearing coefficients in a mathematical model of the fully assembled machine, the real part of the eigenvalue associated with the first balance resonance of the generator rotor became positive. This paper shows the successful results obtained by combining diagnostic techniques based on mathematical models of journal bearings and shaft train with detailed analyses of monitoring data aimed to investigate the effects of the hot alignment of rotating machines on the occurrence of oil-whip instability onsets.

  8. Pipe rupture test results: 4-inch pipe whip tests under PWR LOCA conditions

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Ueda, Shuzo; Isozaki, Toshikuni; Kato, Rokuro; Kurihara, Ryoichi; Yano, Toshikazu; Miyazono, Shohachiro

    1982-09-01

    This report summarizes the results of 4-inch pipe whip tests (RUN No. 5506, 5507, 5508 and 5604) under the PWR LOCA conditions. The dynamic behaviors of the test pipe and restraints were studied in the tests. In the tests, the gap between the test pipe and the restraints was kept at the constant value of 8.85 mm and the overhang length was varied from 250 mm to 650 mm. The dynamic behaviors of the test pipe and the restraint were made clear by the outputs of strain gages and the measurements of residual deformations. The data of water hammer in subcooled water were also obtained by the pressure transducers mounted on the test pipe. The main conclusions obtained from the tests are as follows. (1) The whipping of pipe can be prevented more effectively as the overhang length becomes shorter. (2) The load acting on the restraint-support structure becomes larger as the overhang length becomes shorter. (3) The restraint farther from the break location does not limit the pipe movement except for the first impact when the overhang length is long. (4) The ultimate moment M sub(u) of the pipe at the restraint location can be used to predict the plastic collapse of the whipping pipe. (5) The restraints slide along the pipe axis and are subjected to bending moment, when the overhang length is long. (author)

  9. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

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

  10. Snow noise disturbance in Antarctic radio communications and development of mobile antenna for snow vehicle in Antarctica

    Directory of Open Access Journals (Sweden)

    Isao Fukushima

    1997-07-01

    Full Text Available Radio operators of the Japanese Antarctic Research Expedition (JARE have encountered critical radio noise disturbances caused by blizzards during oversnow travel. This noise appears to be caused by corona discharge at the edges of the vertical whip antenna. This paper describes several examples of snow noise experienced in Antarctica by JARE, the mechanism of generation of the noise, and a method of reducing the intensity of the noise. It also describes a High Effeciency Transmission Line Antenna which is small enough to mount on a snow vehicle and reduces the intensity of the snow noise.

  11. Hamstrings tendon graft preparation for anterior cruciate ligament reconstruction using the WhipKnotTM soft tissue cinch technique.

    Directory of Open Access Journals (Sweden)

    Amin Masoumiganjgah

    2012-04-01

    Full Text Available BackgroundAppropriate graft tension and secure graft incorporation inbone tunnels are essential for successful anterior cruciateligament (ACL reconstruction using hamstrings tendonautografts. The WhipKnot™ soft tissue cinch, introduced bySmith and Nephew in 2004, is an alternative option to thecommonly used whipstitch technique during preparation ofthe hamstring autograft in ACL reconstruction.AimsTo investigate the effectiveness of the WhipKnot™ softtissue cinch and technique during the preparation of thetendon graft for ACL reconstruction.MethodA total of 33 ACL reconstruction operations performedbetween February 2011 and December 2011 were includedin this study. These were performed by a single seniorsurgeon who used the Whipknot™ technique for thepreparation of each graft. Four were used for eachoperation; two for each end of the harvested hamstringstendons, including semitendinosus and gracilis tendonsrespectively.ResultsIn total, 132 WhipKnots were used during the kneeoperations. Use of the WhipKnot™ technique resulted insuccessful graft preparations, tensioning and effective graftplacement in the tibial and femoral tunnels in almost allinstances. Only one case of WhipKnot™ failure (slippagewas recorded.ConclusionThese results indicate that the Whipknot™ technique is asafe, reliable and practical option for the preparation of thehamstrings autografts.

  12. Pipe rupture test results; 4 inch pipe whip tests under BWR operational condition-clearance parameter experiments

    International Nuclear Information System (INIS)

    Ueda, Syuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kurihara, Ryoichi; Kato, Rokuro; Saito, Kazuo; Miyazono, Shohachiro

    1981-05-01

    The purpose of pipe rupture studies in JAERI is to perform the model tests on pipe whip, restraint behavior, jet impingement and jet thrust force, and to establish the computational method for analyzing these phenomena. This report describes the experimental results of pipe whip on the pipe specimens of 4 inch in diameter under BWR condition on which the pressure is 6.77 MPa and the temperature is 285 0 C. The pipe specimens were 114.3 mm (4 inch) in diameter and 8.6 mm in thickness and 4500 mm in length. Four pipe whip restraints used in the tests were the U-bar type of 8 mm in diameter and fabricated from type 304 stainless steel. The experimental parameter was the clearance (30, 50 and 100 mm). The dynamic strain behavior of the pipe specimen and the restraints was investigated by strain gages and their residual deformation was obtained by measuring marking points provided on their surface. The Pressure-time history in the pipe specimens was also obtained by pressure gages. The maximum pipe strain is caused near the restraints and increases with increase of the clearance. The experimental results of pipe whip tests indicate the effectiveness of pipe whip restraints. The ratio of absorbed strain energy of the pipe specimen to that of the restraints is nearly constant for different clearances at the overhang length of 400 mm. (author)

  13. Superluminal antenna

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.; Potter, James M.; Romero, William P.; Wang, Zhi-Fu

    2018-04-17

    A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

  14. HF-laser program

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Sandia's HF-laser program for FY 77 and FY 78 was revised in June 1977 in order to meet several new program milestones. Research progress is reported on: objective of HF oscillator-amplifier studies using H 2 -F 2 gas mixtures; characteristics of large-volume oscillator using H 2 -F 2 mixtures; characteristics of large-volume amplifier using H 2 -F 2 mixtures; experimental results of the oscillator-amplifier study; objective of high-quality discharge-initiated SF 6 -HI oscillator-preamplifier system; pin-discharge-initiated oscillator and first beam expander; fast-discharge-initiated preamplifiers; reflecting beam expanders for oscillator-preamplifier system; beam quality of discharge-initiated oscillator-preamplifier system; short pulse option for discharge initiated SF 6 -HI system; H 2 -F 2 electron-beam-initiated oscillator-preamplifier system; chamber for HF-laser focusing experiments; computer study of parasitic oscillations in HF amplifiers and oscillators; kinetics upgrade of HF-laser code; repetitivey ignited flowing H 2 -F 2 -O 2 mixtures; spontaneous detonations in multiatmosphere H 2 -F 2 -O 2 mixtures; high-pressure H 2 -F 2 laser studies; and time sequenced energy extraction on the high xenon laser

  15. The whip spider collection (Arachnida, Amblypygi held in the Natural History Museum Vienna, Austria

    Directory of Open Access Journals (Sweden)

    Seiter, Michael

    2013-11-01

    Full Text Available We present data and remarks on the history and contents of the whip spider collection housed in the Natural History Museum of Vienna, Austria. The collection comprises a total of 167 specimens from 4 families, 10 genera and 27 species. It includes types of four species: Charinus ioanniticus (Kritscher, 1959, Damon brachialis Weygoldt, 1999, Phrynus parvulus (Pocock, 1902 and Paraphrynus mexicanus (Bilimek, 1867. Short notes on interesting objects and former curators are provided as well as an appendix with a list of species kept alive by Michael Seiter.

  16. Broadband standard dipole antenna for antenna calibration

    Science.gov (United States)

    Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

    1995-06-01

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

  17. Modelling of Aquitaine II pipe whipping test with EUROPLEXUS fast dynamics code

    International Nuclear Information System (INIS)

    Potapov, S.

    2003-01-01

    To validate the modelling of multi-physics phenomena with EUROPLEXUS code we considered a pipe whipping problem occurring in thermal hydraulic conditions of a Loss of Coolant Accident in PWR primary circuit. Two numerical fluid-structure interaction (FSI) models, a simplified 'pipe-like' model and a mixed 1D/3D model, were used to simulate both the conditioning phase and a phase of whipping. The results of calculations were compared with existing experimental data. Analysis of numerical results shows that both models give a good prediction of global behaviour of the coupled fluid-structure system, namely for pipe displacements and stresses in the pipe walls, as well as for pressure and velocity in the fluid. By comparison with experimental data, we show that only the mixed EUROPLEXUS model, where the pipe elbow is discretized with shells, allows us to estimate correctly the time history and maximum value of the contact force between the pipe and the obstacle. The 1D model with reduced kinematics (rigid cross section hypothesis) does not allow the correct detection of contact phenomenon. This study shows that the use of mixed numerical models containing simplified and totally 3D parts duly interconnected allows a very efficient and CPU inexpensive numerical analysis which is able to take into account different global and local physical phenomena. (author)

  18. Antennas in inhomogeneous media

    CERN Document Server

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

    2013-01-01

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

  19. HF/DF chemical labs

    International Nuclear Information System (INIS)

    Meinzer, R.A.

    1987-01-01

    This paper provides the essential details to understand and design HF/DF and related types of chemical lasers. The basic operation of the HF/DF chemical laser is described. The details of the excitation chemistry are presented and the pertinent laser physics is described. A description of the various laser components is given and the analytical models for the HF/DF chemical laser are discussed. A brief description of the chain reaction HF/DF chemical laser is offered

  20. Changing Human-Animal Relationships in Sport: An Analysis of the UK and Australian Horse Racing Whips Debates

    Directory of Open Access Journals (Sweden)

    Raewyn Graham

    2016-05-01

    Full Text Available Changing social values and new technologies have contributed to increasing media attention and debate about the acceptable use of animals in sport. This paper focuses on the use of the whip in thoroughbred horse racing. Those who defend its use argue it is a necessary tool needed for safety, correction and encouragement, and that it does not cause the horse any pain. For those who oppose its use, it is an instrument of cruelty. Media framing is employed to unpack the discourses played out in print and social media in the UK (2011 and Australia (2009 during key periods of the whip debate following the introduction of new whip rules. Media coverage for the period August 2014–August 2015 for both countries is also considered. This paper seeks to identify the perceptions of advocates and opponents of the whip as portrayed in conventional and social media in Australia and the UK, to consider if these perceptions have changed over time, and whose voices are heard in these platforms. This paper contributes to discussions on the impacts that media sites have either in reinforcing existing perspectives or creating new perspectives; and importantly how this impacts on equine welfare.

  1. The effect of fermentable carbohydrates on experimental swine dysentery and whip worm infections in pigs

    DEFF Research Database (Denmark)

    Thomsen, Lisbeth E.; Knudsen, Knud Erik Bach; Jensen, Tim Kåre

    2007-01-01

    ingredients were composed. Both diets were based on triticale and barley and supplemented with either rape seed cake (Diet 1) or dried chicory root and sweet lupins (Diet 2). The study had a three-factorial design, with eight groups of pigs receiving Diet I or Diet 2, +/- B. hyodysenteriae, and +/- T suis......An experiment was conducted to study the effect of diets with contrasting fermentability in the large intestine on experimental infections with Brachyspira hyodysenteriae, the causative agent of swine dysentery, and the whip worm, Trichuris suis, in pigs. Two diets with organically grown....... Pigs fed Diet 2 and challenged with B. hyodysenteriae did not develop swine dysentery and B. hyodysenteriae was not demonstrated in any of the pigs during the study. In contrast, 94% of the B. hyodysenteriae challenged pigs fed Diet I showed clinical symptoms of swine dysentery and all the pigs were...

  2. Miniaturization design and implementation of magnetic field coupled RFID antenna

    Science.gov (United States)

    Hu, Tiling

    2013-03-01

    The development of internet of things has brought new opportunities and challenges to the application of RFID tags. Moreover, the Miniaturization application trend of tags at present has become the mainstream of development. In this paper, the double-layer design is to reduce the size of HF antenna, and the magnetic null point of magnetic reconnection region between the RLC resonant circuit and the reader provides sufficient energy to the miniaturization of antenna. The calculated and experimental results show that the miniaturization of HF antennas can meet the reading and writing requirement of the international standard ISO/IEC14443 standard. The results of this paper may make a positive contribution to the applications of RFID technology.

  3. HF-laser program

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The HF laser is an attractive candidate driver for a large-system ICF scientific demonstration facility, for an ICF experimental power reactor and for a commercial laser--fusion power reactor. Previous accomplishments of the program have included demonstrations of high efficiency and high energy capability, efficient energy extraction from HF amplifiers, good beam quality and focusability, and short-pulse generation and amplification. In the reporting period, beam quality has been determined to be near-diffraction limited for a short pulsewidth (6 ns to 25 ns) oscillator-amplifier chain, suppression of amplified spontaneous emission has been demonstrated on an individual spectral line, high-pressure characteristics have been determined for the Phoenix I amplifier, and detailed comparisions between the kinetic code and experiments have been made. Details of two major upcoming experiments are also included. The first is energy extraction and beam quality measurements on the Phoenix I amplifier operating under saturated output power conditions. The second experiment, using a newly designed amplifier (Phoenix II), is designed to demonstrate the concept of angular-multiplexing: a pulse width-compression scheme

  4. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  5. Coaxial antenna for lower hybrid heating

    International Nuclear Information System (INIS)

    Le Gardeur, R.J.

    1981-02-01

    A coaxial antenna for the heating of toroidal plasmas has been conceived and constructed. Being wholly metallic (stainless steel), the several coaxial ceramic passages assuring the transit of the H.F. energy into vacuum being situated far from the plasma, the use of such antennas can be envisaged in next generation machines where the environment is particularily severe. The coaxial design (having a lower internal impedance than a wave guide) reduces the electric fields present in the antenna-plasma interface, assuring, at the same time, a spatial uniformity of the fields making possible a substantial reduction in the transmitted power density. The main technological advantages (with respect to a wave guide grill structure) are: (a) simplification of the construction especially in multi-channel systems (b) quasi-elimination of the problems associated with the ceramic windows transmitting the H.F. energy (c) absence of a low frequency cut-off making possible to place launching structures in vertical chimneys where space is limited (d) an eventual reduction of certain phenomena inherent to this type of heating such as particle acceleration, space charge separation, pondemotive forces etc

  6. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  7. Antenna Pattern Range (APR)

    Data.gov (United States)

    Federal Laboratory Consortium — TheAntenna Pattern Range (APR)features a non-metallic arch with a trolley to move the transmit antenna from the horizon to zenith. At the center of the ground plane,...

  8. Belt whippings in Brazilian Jiu Jitsu: a case study exploring conditional consent and the value of options

    Directory of Open Access Journals (Sweden)

    Rob Lawlor

    2015-11-01

    Full Text Available In this paper, considering the practice of whipping students with belts, when grading, I argue that the most obvious objections, considering the harm involved or questioning the validity of the consent, are inconclusive. However, I argue that, even if we assume the consent is valid, the practice can still be shown to be problematic. This argument relies on the idea of conditional consent.

  9. HF-DLLME

    OpenAIRE

    Simão, Vanessa

    2015-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2015. Neste trabalho foi proposto, pela primeira vez, a combinação simultânea das técnicas de microextração em fase líquida suportada em fibra oca (HF-LPME) e microextração líquido-líquido dispersiva (DLLME) para aplicação em amostras líquidas. Dois estudos foram desenvolvidos utilizando a metodologia proposta, a qua...

  10. High energy HF pulsed lasers

    International Nuclear Information System (INIS)

    Patterson, E.L.; Gerber, R.A.

    1976-01-01

    Recent experiments show that pulsed HF lasers are capable of producing high energy with good efficiency. Preliminary experiments show that the laser radiation from the high-gain medium can be controlled with a low-power probe laser beam or with low-level feedback. These results indicate that the HF laser may have potential for second-generation laser fusion experiments

  11. Pipe rupture test results; 6 in. pipe whip test under BWR LOCA conditions

    International Nuclear Information System (INIS)

    Kurihara, Ryoichi; Yano, Toshikazu; Ueda, Shuzo; Isozaki, Toshikuni; Miyazaki, Noriyuki; Kato, Rokuro; Miyazono, Shohachiro

    1983-02-01

    A series of pipe rupture tests has been performed in JAERI to demonstrate the safety of the primary coolant circuits in the event of pipe rupture, in nuclear power plants. The present report summarizes the results of 6 in. pipe whip tests (RUN 5605, 5606), under BWR LOCA conditions (285 0 C, 6.8 MPa), which were performed in August, 1981. The test pipe is made of Type 304 stainless steel and its outer diameter is 6 in. and its thickness is 11.1 mm. The restraints are made of Type 304 stainless steel and its diameter is 16.0 mm. Two restraints were set on the restraint support with clearance of 100 mm. Overhang length was varied as the parameter in these tests and was 300 mm or 700 mm. The following results are obtained. (1) The deformations of a pipe and restraints are limited effectively by shorter overhang length of 300. However, they become larger when the overhang length is 700 mm, and the pipe deforms especially at the setting point of restraints. (2) Velocity at the free end of pipe becomes about 30 m/sec just after the break. However, velocity at the setting point of restraint becomes about only 4 m/sec just after the break. (3) It seems from the comparison between the 4 in. tests and 6 in. tests that the maximum restraint force of 6 in. tests is about two times as large as that of 4 in. tests. (author)

  12. Antenna theory: Analysis and design

    Science.gov (United States)

    Balanis, C. A.

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

  13. Antenna Controller Replacement Software

    Science.gov (United States)

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

    2010-01-01

    The Antenna Controller Replacement (ACR) software accurately points and monitors the Deep Space Network (DSN) 70-m and 34-m high-efficiency (HEF) ground-based antennas that are used to track primarily spacecraft and, periodically, celestial targets. To track a spacecraft, or other targets, the antenna must be accurately pointed at the spacecraft, which can be very far away with very weak signals. ACR s conical scanning capability collects the signal in a circular pattern around the target, calculates the location of the strongest signal, and adjusts the antenna pointing to point directly at the spacecraft. A real-time, closed-loop servo control algorithm performed every 0.02 second allows accurate positioning of the antenna in order to track these distant spacecraft. Additionally, this advanced servo control algorithm provides better antenna pointing performance in windy conditions. The ACR software provides high-level commands that provide a very easy user interface for the DSN operator. The operator only needs to enter two commands to start the antenna and subreflector, and Master Equatorial tracking. The most accurate antenna pointing is accomplished by aligning the antenna to the Master Equatorial, which because of its small size and sheltered location, has the most stable pointing. The antenna has hundreds of digital and analog monitor points. The ACR software provides compact displays to summarize the status of the antenna, subreflector, and the Master Equatorial. The ACR software has two major functions. First, it performs all of the steps required to accurately point the antenna (and subreflector and Master Equatorial) at the spacecraft (or celestial target). This involves controlling the antenna/ subreflector/Master-Equatorial hardware, initiating and monitoring the correct sequence of operations, calculating the position of the spacecraft relative to the antenna, executing the real-time servo control algorithm to maintain the correct position, and

  14. Automotive hexband antenna for AM/FM/GPS/SDARS and AMPS/PCS1900 cell phone in an only 65 mm high housing

    International Nuclear Information System (INIS)

    Kammerer, J; Reiter, L; Lindenmeier, S

    2013-01-01

    Nowadays cars are equipped frequently with typical 400 mm long active AM/FM antennas mounted on top close to the rear windshield. In [1], we presented a novel capacitive coupled helical antenna with a height of only 140 mm which performs equivalent to such an 400 mm long antenna. In the next step the antenna height has been reduced to only 56 mm in order to be placed in a low 65 mm housing in combination with other decoupled antennas. The measured results for AM/FM are close to the performance of a whip antenna of 900 mm length. The GPS and SDARS antennas are realized in a combination of two table-formed ring structures with a maximum gain for LHCP at 2339 MHz with 2.9 dBi in zenith and with 5.2 dBi in zenith for RHCP at 1575 MHz with GPS. The VSWR of the cell phone antenna is below 3 for AMPS and PCS1900.

  15. A Novel Cellular Handset Design for an Enhanced Antenna Performance and a Reduced SAR in the Human Head

    Directory of Open Access Journals (Sweden)

    Salah I. Al-Mously

    2008-01-01

    Full Text Available This paper presents a novel cellular handset design with a bottom-mounted short loaded-whip antenna. This new handset design is modeled and simulated using a finite difference time-domain (FDTD-based platform SEMCAD. The proposed handset is based on a current commercially available bar-phone type with a curvature shape, keypad positioned above the screen, and top-mounted antenna. The specific absorption rates (SARs are determined computationally in the specific anthropomorphic mannequin (SAM and anatomically correct model of a human head when exposed to the EM-field radiation of the proposed cellular handset and the handset with top-mounted antenna. The two cellular handsets are simulated to operate at both GSM standards, 900 MHz as well as 1800 MHz, having different antenna dimensions and intput power of 0.6 W and 0.125 W, respectively. The proposed human hand holding the two handset models is a semirealistic hand model consists of three tissues: skin, muscle, and bone. The simulations are conducted with handset positions based on the IEEE standard 1528-2003. The results show that the proposed handset has a significant improvement of antenna efficiency when it is hand-held close to head, as compared with the handset of top-mounted antenna. Also, the results show that a significant reduction of the induced SAR in the human head-tissues can be achieved with the proposed handset.

  16. Hf på VUC

    DEFF Research Database (Denmark)

    Pless, Mette; Hansen, Niels-Henrik Møller

    . Konkret har forskningsprojektet 3 mål: At afdække hf-kursisternes tidligere uddannelsesforløb og -erfaringer, før de starter på hf på VUC.At afdække, hvordan mødet med uddannelsens studiemiljø opleves af kursisterne, og ikke mindst kursisternes oplevelse af undervisningsformer, lærere mm.At afdække, hvad...

  17. Phased array antenna control

    Science.gov (United States)

    Doland, G. D. (Inventor)

    1978-01-01

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

  18. Experiments with dipole antennas

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2009-01-01

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

  19. Cellular Reflectarray Antenna

    Science.gov (United States)

    Romanofsky, Robert R.

    2010-01-01

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

  20. Compact Antenna Range

    Data.gov (United States)

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

  1. HF Radio Angle-of-Arrival Measurements and Ionosonde Positioning

    Directory of Open Access Journals (Sweden)

    Lung-Chih Tsai

    2014-01-01

    Full Text Available Since 2010 a 2nd generation NOAA MF/HF radar, also referred to as the VIPIR ionosonde, has been operated at Hualien, Taiwan (23.8973°N, 121.5503°E. The Hualien VIPIR ionosonde is a modern ionospheric radar, fully digitizing complex signal records and using multiple parallel receiver channels for simultaneous signal measurements from multiple spaced receiving antennas. This paper considers radio direction finding based on interferometric phase measurements from a horizontal antenna array in the Hualien VIPIR ionosonde system. We applied the Hermite normal form method to solve the phase-measurement aliasing and least squares problems and improve the radio angle-of-arrival (AOA measurements. Backward ray-tracing simulation has been proposed to determine radio transmitter position. This paper presents a numerical, step by step ray-tracing method based on the IGRF superimposed onto a phenomenological ionospheric electron density model, the TaiWan Ionospheric Model (TWIM. The proposed methodology is successfully applied to locate two experimental HF radio transmitters at Longquan and Chungli with distance errors within 5 km and less than 5% of the great circle distances.

  2. Directional borehole antenna - Theory

    International Nuclear Information System (INIS)

    Falk, L.

    1992-02-01

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

  3. A computational procedure for the investigation of whipping effect on ITER High Energy Piping and its application to the ITER divertor primary heat transfer system

    Energy Technology Data Exchange (ETDEWEB)

    Spagnuolo, G.A., E-mail: Alessandro.Spagnuolo@kraftanlagen.com [Kraftanlagen Heidelberg Gmbh, Im Breitspiel 7, D-69126 Heidelberg (Germany); Dell’Orco, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Di Maio, P.A. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo Viale delle Scienze, 90128 Palermo (Italy); Mazzei, M. [Kraftanlagen Heidelberg Gmbh, Im Breitspiel 7, D-69126 Heidelberg (Germany)

    2015-10-15

    Highlights: • High Energy Piping (HEP) are components containing water or steam with P ≥ 2.0 MPa and/or T ≥ 100 °C. • The whipping effect in HEP may cause dangerous domino effect with relative rupture propagation. • The rapture is envisaged or postulated according to the stress state of piping. • A FEM analysis is performed in order to study the dynamic of whipping effect. • Study of special support to avoid and/or mitigate the whipping effect. - Abstract: The Tokamak Cooling Water System of nuclear facility has the function to remove heat from plasma facing components maintaining coolant temperatures, pressures and flow rates as required and, depending on thermal-hydraulic requirements, its systems are defined as High Energy Piping (HEP) because they contain fluids, such as water or steam, at a pressure greater than or equal to 2.0 MPa and/or at a temperature greater than or equal to 100 °C, or even gas at pressure above the atmospheric one. The French standards contemplate the need to consider the whipping effect on HEP design. This effect happens when, after a double ended guillotine break, the reaction force could create a displacement of the piping which might affect adjacent components. A research campaign has been performed, in cooperation by ITER Organization and University of Palermo, to outline the procedure to check whether whipping effect might occur and assess its potential damage effects so to allow their mitigation. This procedure is based on the guidelines issued by U.S. Nuclear Regulatory Commission. The proposed procedure has been applied to the analysis of the whipping effect of divertor primary heat transfer system HEP, using a theoretical–computational approach based on the finite element method.

  4. Handbook of antenna technologies

    CERN Document Server

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

    2016-01-01

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

  5. GPS antenna designs

    Science.gov (United States)

    Laube, Samuel J. P.

    1987-05-01

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

  6. HF Interference, Procedures and Tools (Interferences HF, procedures et outils)

    Science.gov (United States)

    2007-06-01

    the actual ambient noise floor situation. Besides these HF radio links, special units such as crisis reaction forces are using low power radios for...the origin point on the ground. For ease of arithmetic and typography , the latter option is preferable. The dipole-modelled PLT is located at x = H1

  7. Smart antennas in aerospace applications

    NARCIS (Netherlands)

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

    2010-01-01

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

  8. Zirconium Zr and hafnium Hf

    International Nuclear Information System (INIS)

    Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

    1978-01-01

    The basic methods for extracting and determining Zr(4) and Hf(4) are described. Diantipyrinemethane and its alkyl homologs selectively extract Zr and Hf from HNO 3 solutions in the presence of nitrates. Zr is selectively extracted with tetraethyldiamide of heptyl phosphoric acid (in benzene) as well as with 2-thenoyltrifluoroacetone (in an acid). The latter reagents is suitable for rapid determination of 95 Zr in a mixture with 95 Nb and other fragments. The complexometric determination of Zr is based on formation of a stable complex of Zr with EDTA. The titration is carried out in the presence of n-sulfobenzene-azo-pyrocatechol, eriochrome black T. The determination is hindered by Hf, fluoride-, phosphate-, oxalate- and tartrate-ions. The method is used for determining Zr in zircon and eudialyte ore. Zr is determined photometrically with the aid of xylenol orange, arsenazo 3 and pyrocatechol violet (in phosphorites). Hf is determined in the presence of Zr photometrically with the aid of xylenol orange or methyl-thymol blue. The method is based on Zr being masked with hydrogen peroxide in the presence of sulfate-ions

  9. HF Parameters of Induction Motor

    Directory of Open Access Journals (Sweden)

    M. N. Benallal

    2017-09-01

    Full Text Available This article describes the results of experimental studies of HF input and primary parameters. A simulation model in Matlab SimulinkTM of multiphase windings as ladder circuit of coils is developed. A method for determining the primary parameters of ladder equivalent circuits is presented.

  10. Antennas from theory to practice

    CERN Document Server

    Huang, Yi

    2008-01-01

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

  11. Buoyant Cable Antenna System

    National Research Council Canada - National Science Library

    Gerhard, Erich M

    2008-01-01

    .... For instance, in one embodiment two oppositely extending curves each float and each are pressed by the water in a balanced manner to provide a stable platform for one or more antennas which can be...

  12. Micropatch Antenna Phase Shifting

    National Research Council Canada - National Science Library

    Thursby, Michael

    2000-01-01

    .... We have been looking at the ability of embedded element to adjust the phase shift seen by the element with the goal of being able to remove the phase shifting devices from the antenna and replace...

  13. Micropatch Antenna Phase Shifting

    National Research Council Canada - National Science Library

    Thursby, Michael

    1999-01-01

    .... We have been looking at the ability of embedded element to adjust the phase shift seen by the element wit the goal of being able to remove the phase shifting devices from the antenna and replace...

  14. Microwave antenna holography

    Science.gov (United States)

    Rochblatt, David J.; Seidel, Boris L.

    1992-01-01

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

  15. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    Baity, F.W.

    1987-01-01

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

  16. Antenna for Ultrawideband Channel Sounding

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  17. Stretchable antenna for wearable electronics

    KAUST Repository

    Hussain, Muhammad Mustafa; Hussain, Aftab Mustansir; Shamim, Atif; Ghaffar, Farhan Abdul

    2017-01-01

    Various examples are provided for stretchable antennas that can be used for applications such as wearable electronics. In one example, a stretchable antenna includes a flexible support structure including a lateral spring section having a proximal

  18. Dynamic Flaps Electronic Scan Antenna

    National Research Council Canada - National Science Library

    Gonzalez, Daniel

    2000-01-01

    A dynamic FLAPS(TM) electronic scan antenna was the focus of this research. The novelty S of this SBIR resides in the use of plasma as the main component of this dynamic X-Band phased S array antenna...

  19. Wireless Distributed Antenna MIMO

    DEFF Research Database (Denmark)

    2015-01-01

    The present disclosure relates to system applications of multicore optical fibers. One embodiment relates to a base transceiver station for a wireless telecommunication system comprising a plurality of antenna units arranged in a MIMO configuration and adapted for transmission and/or reception...... of radio-frequency signals, an optical transmitter in the form of an electro-optic conversion unit for each of said plurality of antenna units, each electro-optic conversion unit adapted for converting an RF signal into an optical signal, a plurality of a single core optical fibers for guiding the optical...

  20. Printed MIMO antenna engineering

    CERN Document Server

    Sharawi, Mohammad S

    2014-01-01

    Wireless communications has made a huge leap during the past two decades. The multiple-input-multiple-output (MIMO) technology was proposed in the 1990's as a viable solution that can overcome the data rate limit experienced by single-input-single-output (SISO) systems. This resource is focused on printed MIMO antenna system design. Printed antennas are widely used in mobile and handheld terminals due to their conformity with the device, low cost, good integration within the device elements and mechanical parts, as well as ease of fabrication.A perfect design companion for practicing engineers

  1. Non-standard antennas

    CERN Document Server

    Le Chevalier, Francois; Staraj, Robert

    2013-01-01

    This book aims at describing the wide variety of new technologies and concepts of non-standard antenna systems - reconfigurable, integrated, terahertz, deformable, ultra-wideband, using metamaterials, or MEMS,  etc, and how they open the way to a wide range of applications, from personal security and communications to multifunction radars and towed sonars, or satellite navigation systems, with space-time diversity on transmit and receive. A reference book for designers  in this lively scientific community linking antenna experts and signal processing engineers.

  2. DSN Microwave Antenna Holography

    Science.gov (United States)

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

    1984-01-01

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

  3. The rotational excitation of HF by H

    Science.gov (United States)

    Desrousseaux, Benjamin; Lique, François

    2018-06-01

    The HF molecule is a key tracer of molecular hydrogen in diffuse interstellar medium (ISM). Accurate modelling of the HF abundance in such media requires one to model its excitation by both radiation and collisions. In diffuse ISM, the dominant collisional partners are atomic and molecular hydrogen. We report quantum time-independent calculations of collisional cross-sections and rate coefficients for the rotational excitation of HF by H. The reactive hydrogen exchange channels are taken into account in the scattering calculations. For the first time, HF-H rate coefficients are provided for temperature ranging from 10 to 500 K. The strongest collision-induced rotational HF transitions are those with Δj = 1, and the order of magnitude of the new HF-H rate coefficients is similar to that of the HF-H2 ones previously computed. As a first application, we simulate the excitation of HF by both H and H2 in typical diffuse ISM. We show that, depending on the rotational transition, hydrogen atoms increase or decrease the simulated excitation temperatures compared to collisional excitation only due to H2 molecules. Such results suggest that the new HF-H collisional data have to be used for properly modelling the abundance of HF in diffuse ISM.

  4. Optical response of bowtie antennas

    Science.gov (United States)

    Guo, Ying-Nan; Pan, Shi; Li, Xu-Feng; Wang, Shuo; Wang, Qiao

    2010-10-01

    Optical properties of bowtie antennas are investigated using a numerical method of finite-difference time-domain (FDTD). The optical response in the antenna feed gap is simulated as functions of its geometry parameters (flare angle, arm length, apex width, thickness, gap dimension, as well as the index of substrate), which provide a clear guideline to exploit such antenna structures in practice.

  5. Finishing and Commissioning the New Arecibo HF Facility

    Science.gov (United States)

    Sulzer, M. P.; Gonzalez, S. A.

    2011-12-01

    The imminent completion of the major tasks in the construction of the New Arecibo HF facility means that we must verify that the components are working as intended. The antenna system and the transmitters must be separately commissioned before they can be connected together so that we an be sure it will provide 83 dbW at 8.175 MHz, and 80 dbW at 5.1 MHz. The antenna system will be ready for initial testing in September. It Illuminates the 305 meter dish using dipoles near the surface of the dish transmitting upward to a wire mesh sub-reflector. There are three crossed dipoles for each of the two frequencies. The dipoles are supported on towers mounted on concrete pads underneath the dish. Each dipole element is connected to a transmitter through a three inch coax line. The tower foundations are nearly complete, and the towers will be erected in early September, and we expect to have at least one crossed dipole in place for initial testing by the end of September. We will need to make some measurements on the antenna system to ensure that it meets our requirements. One requirement is to match the antenna impedance to the transmission line and the transmitter closely enough to meet the transmitter specifications, the closer, the better. We have additional requirements; for example, it is necessary for efficient use of the facility that the polarization be close to circular. In most experiments, we want O mode excitation. If we were to transmit linear only half the power would reach the reflection height. The symmetry of the system assures that most of the conditions for achieving accurate circular polarization are met, but one condition is not: that exciting the transmitters driving the orthogonal elements at 90 degrees assures 90 degree separation in the corresponding antenna currents. One of the dipoles of each pair points toward the center of the array. If we think of the three crossed dipoles as consisting of a reference and two that are excited relative to it

  6. Special Topics in HF Propagation

    Science.gov (United States)

    1979-11-01

    Capitaine de Frigate P.Italley Dr T.SJones Ing6nieur en Chef au CNET Physics Department 38 -40 rue du Gdn~ral Leclerc University of Leicester 9213 i1...fre’qiancý. A t’ctailcd discussion of HF reliability is giver in A companion paiper (MASLIN, N.M . 197(j)) the result tic ligs 4 atad % i-. sumniart-aed...conttoutt to determine if treie :s an additional zonal gqt.ient but wa shall ceo tto.., tnC companion Layttacings that it it, negliit.-tle. F:gur:!i 7A

  7. Electromagnetic reciprocity in antenna theory

    CERN Document Server

    Stumpf, Martin

    2018-01-01

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

  8. Antenna theory analysis and design

    CERN Document Server

    Balanis, Constantine A

    2005-01-01

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

  9. MO-HF-C alloy composition

    International Nuclear Information System (INIS)

    Whelan, E.P.; Kalns, E.

    1987-01-01

    This patent describes, as an article of manufacture, a cast ingot of a molybdenum-hafnium-carbon alloy consisting essentially by weight of about 0.6% to about 1% Hf, about 0.045% to about 0.08% C, and the balance essentially molybdenum. The amount of Hf and C present are substantially stoichiometric with respect to HfC and within about +-15% of stoichiometry. The ingot is characterized in that it has a substantially less tendency to crack compared to alloys containing Hf in excess of about 1% by weight and carbon in excess of 0.08% by weight, without substantial diminution in strength properties of the alloy

  10. The 'Whip-Stow' procedure: an innovative modification to the whipple procedure in the management of premalignant and malignant pancreatic head disease.

    Science.gov (United States)

    Jeyarajah, D Rohan; Khithani, Amit; Curtis, David; Galanopoulos, Christos A

    2010-01-01

    Pancreaticoduodenectomy (PD) is the standard of care in the treatment of premalignant and malignant diseases of the head of the pancreas. Variability exists in anastomosis with the pancreatic remnant. This work describes a safe and easy modification for the pancreatic anastomosis after PD. Ten patients underwent the "Whip-Stow" procedure for the management of the pancreatic remnant. PD combined with a Puestow (lateral pancreaticojejunostomy [LPJ]) was completed using a running single-layer, 4-0 Prolene obeying a duct-to-mucosa technique. LPJ and pancreaticogastrostomy (PG) historical leak rates are reported to be 13.9 and 15.8 per cent, respectively. Mortality, leak, and postoperative bleeding rates were 0 per cent in all patients. The Whip-Stow was completed without loops or microscope with a 4-0 single-layer suture decreasing the time and complexity of the anastomosis. Average time was 12 minutes as compared with the 50 minutes of a 5 or 6-0 interrupted, multilayered duct-mucosa anastomosis. Benefits included a long-segment LPJ. In this study, the Whip-Stow procedure has proven to be a safe and simple approach to pancreatic anastomosis in selected patients. This new technique provides the benefit of technical ease while obeying the age old principles of obtaining a wide duct to mucosa anastomosis.

  11. Multiple Antenna Systems with Inherently Decoupled Radiators

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  12. Development of HF-systems for electron storage systems

    International Nuclear Information System (INIS)

    Androsov, V.P.; Karnaukhov, I.M.; Popkov, Yu.P.; Reva, S.N.; Telegin, Yu.N.

    1999-01-01

    Development of HF systems for electron storages is described. Its final task is construction of 100 kW HF station at 699,3 MHz frequency consisting from low-power HF system, klystron amplifier, wave line for HF power transmission and accelerating section. Functional parameters of HF station are given

  13. Next Generation of Magneto-Dielectric Antennas and Optimum Flux Channels

    Science.gov (United States)

    Yousefi, Tara

    There is an ever-growing need for broadband conformal antennas to not only reduce the number of antennas utilized to cover a broad range of frequencies (VHF-UHF) but also to reduce visual and RF signatures associated with communication systems. In many applications antennas needs to be very close to low-impedance mediums or embedded inside low-impedance mediums. However, for conventional metal and dielectric antennas to operate efficiently in such environments either a very narrow bandwidth must be tolerated, or enough loss added to expand the bandwidth, or they must be placed one quarter of a wavelength above the conducting surface. The latter is not always possible since in the HF through low UHF bands, critical to Military and Security functions, this quarter-wavelength requirement would result in impractically large antennas. Despite an error based on a false assumption in the 1950’s, which had severely underestimated the efficiency of magneto-dielectric antennas, recently demonstrated magnetic-antennas have been shown to exhibit extraordinary efficiency in conformal applications. Whereas conventional metal-and-dielectric antennas carrying radiating electric currents suffer a significant disadvantage when placed conformal to the conducting surface of a platform, because they induce opposing image currents in the surface, magnetic-antennas carrying magnetic radiating currents have no such limitation. Their magnetic currents produce co-linear image currents in electrically conducting surfaces. However, the permeable antennas built to date have not yet attained the wide bandwidth expected because the magnetic-flux-channels carrying the wave have not been designed to guide the wave near the speed of light at all frequencies. Instead, they tend to lose the wave by a leaky fast-wave mechanism at low frequencies or they over-bind a slow-wave at high frequencies. In this dissertation, we have studied magnetic antennas in detail and presented the design approach and

  14. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  15. Broadband Monopole Antenna

    Science.gov (United States)

    2017-09-14

    December 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0002] United States Patent Application Ser. No. 15/220,692 filed on July 27, 2016 is incorporated by...antenna operating near 2.5 GHz to obtain an octave of bandwidth. One solution for this is given by Werner et al. in United States Patent

  16. Positron annihilation studies in Hf doped YBCO

    International Nuclear Information System (INIS)

    Gopalan, P.; Priya, E.R.; Premila, M.; Sundar, C.S.; Gopinathan, K.P.

    1992-01-01

    The variation of positron lifetime and oxygen stoichiometry as a function of quench temperature has been measured in undoped and 0.5at%, 0.75at%, and 1.0 at% Hf doped YBCO. In both the undoped and Hf doped samples, the lifetime decreases and the oxygen content increases as the quench temperature is lowered from 900degC to 300degC. The lifetime in the tetragonal phase (900degC) decreases with the increase in Hf content, whereas in the orthorhombic phase (450degC) it increases. The difference in lifetime between the tetragonal and orthorhombic phases decreases with the increase in the Hf content. These trends are discussed in terms of the influence of Hf doping on the oxygen content and the positron density distribution in YBCO

  17. Antenna conditioning with insulating antenna tiles in Phaedrus-T

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  18. Stretchable antenna for wearable electronics

    KAUST Repository

    Hussain, Muhammad Mustafa

    2017-04-13

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

  19. A Compact UWB Diversity Antenna

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2014-01-01

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

  20. Efficient Placement of Directional Antennas

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-20

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

  1. Aspects of HF radio propagation

    Directory of Open Access Journals (Sweden)

    Stephane Saillant

    2009-06-01

    Full Text Available

    radio systems. From the point of view Working Group 2 of the COST 296 Action, interest lies with effects associated

    with propagation via the ionosphere of signals within the HF band. Several aspects are covered in this paper:

    a The directions of arrival and times of flight of signals received over a path oriented along the trough have

    been examined and several types of propagation effects identified. Of particular note, combining the HF observations

    with satellite measurements has identified the presence of irregularities within the floor of the trough that

    result in propagation displaced from the great circle direction. An understanding of the propagation effects that

    result in deviations of the signal path from the great circle direction are of particular relevance to the operation

    of HF radiolocation systems.

    b Inclusion of the results from the above mentioned measurements into a propagation model of the northerly

    ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough

    and the use of this model to predict the coverage expected from transmitters where the signals impinge on the

    northerly ionosphere

  2. Minimum Q Electrically Small Antennas

    DEFF Research Database (Denmark)

    Kim, O. S.

    2012-01-01

    Theoretically, the minimum radiation quality factor Q of an isolated resonance can be achieved in a spherical electrically small antenna by combining TM1m and TE1m spherical modes, provided that the stored energy in the antenna spherical volume is totally suppressed. Using closed-form expressions...... for a multiarm spherical helix antenna confirm the theoretical predictions. For example, a 4-arm spherical helix antenna with a magnetic-coated perfectly electrically conducting core (ka=0.254) exhibits the Q of 0.66 times the Chu lower bound, or 1.25 times the minimum Q....

  3. Catecholamines, cardiac natriuretic peptides and chromogranin A: evolution and physiopathology of a 'whip-brake' system of the endocrine heart.

    Science.gov (United States)

    Tota, Bruno; Cerra, Maria Carmela; Gattuso, Alfonsina

    2010-09-15

    In the past 50 years, extensive evidence has shown the ability of vertebrate cardiac non-neuronal cells to synthesize and release catecholamines (CA). This formed the mindset behind the search for the intrinsic endocrine heart properties, culminating in 1981 with the discovery of the natriuretic peptides (NP). CA and NP, co-existing in the endocrine secretion granules and acting as major cardiovascular regulators in health and disease, have become of great biomedical relevance for their potent diagnostic and therapeutic use. The concept of the endocrine heart was later enriched by the identification of a growing number of cardiac hormonal substances involved in organ modulation under normal and stress-induced conditions. Recently, chromogranin A (CgA), a major constituent of the secretory granules, and its derived cardio-suppressive and antiadrenergic peptides, vasostatin-1 and catestatin, were shown as new players in this framework, functioning as cardiac counter-regulators in 'zero steady-state error' homeostasis, particularly under intense excitatory stimuli, e.g. CA-induced myocardial stress. Here, we present evidence for the hypothesis that is gaining support, particularly among human cardiologists. The actions of CA, NP and CgA, we argue, may be viewed as a hallmark of the cardiac capacity to organize 'whip-brake' connection-integration processes in spatio-temporal networks. The involvement of the nitric oxide synthase (NOS)/nitric oxide (NO) system in this configuration is discussed. The use of fish and amphibian paradigms will illustrate the ways that incipient endocrine-humoral agents have evolved as components of cardiac molecular loops and important intermediates during evolutionary transitions, or in a distinct phylogenetic lineage, or under stress challenges. This may help to grasp the old evolutionary roots of these intracardiac endocrine/paracrine networks and how they have evolved from relatively less complicated designs. The latter can also be used

  4. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier

    2013-01-01

    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

  5. Antennas on circular cylinders

    DEFF Research Database (Denmark)

    Knudsen, H. L.

    1959-01-01

    On the basis of the results obtained by Silver and Saunders [4] for the field radiated from an arbitrary slot in a perfectly conducting circular cylinder, expressions have been derived for the field radiated by a narrow helical slot, with an arbitrary aperture field distribution, in a circular...... antenna in a circular cylinder. By a procedure similar to the one used by Silver and Saunders, expressions have been derived for the field radiated from an arbitrary surface current distribution on a cylinder surface coaxial with a perfectly conducting cylinder. The cases where the space between the two...

  6. Ultra wideband antennas design, methodologies, and performance

    CERN Document Server

    Galvan-Tejada, Giselle M; Jardón Aguilar, Hildeberto

    2015-01-01

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

  7. The Ultrawideband Leaky Lens Antenna

    NARCIS (Netherlands)

    Bruni, S.; Neto, A.; Marliani, F.

    2007-01-01

    A novel directive and nondispersive antenna is presented: the ultrawideband (UWB) leaky lens. It is based on the broad band Cherenkov radiation occurring at a slot printed between different infinite homogeneous dielectrics. The first part of the paper presents the antenna concept and the UWB design.

  8. Antennas for light and plasmons

    NARCIS (Netherlands)

    Dikken, D.J.W.

    2015-01-01

    Antennas have been used for over a century as emitters, scatterers and receivers of electromagnetic waves. All wireless communication devices, such as radio, mobile phones and satellite communication are strongly dependent on the capability of an antenna to localize propagating electromagnetic waves

  9. Optically Controlled Phased Array Antenna

    National Research Council Canada - National Science Library

    Garafalo, David

    1998-01-01

    .... The antenna is a 3-foot by 9 foot phased array capable of a scan angle of 120 degrees. The antenna was designed to be conformal to the cargo door of a large aircraft and is designed to operate in the frequency range of 830 - 1400 MHz with a 30...

  10. Backfire antennas with dipole elements

    DEFF Research Database (Denmark)

    Nielsen, Erik Dragø; Pontoppidan, Knud

    1970-01-01

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

  11. Slot-Coupled Barbel Antenna

    DEFF Research Database (Denmark)

    Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

    2016-01-01

    A novel slot-coupled barbel antenna is designed and analyzed. A sensitivity analysis performed in order to improve the bandwidth, while the center frequency is kept constant.......A novel slot-coupled barbel antenna is designed and analyzed. A sensitivity analysis performed in order to improve the bandwidth, while the center frequency is kept constant....

  12. DEA deformed stretchable patch antenna

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  13. The ICRF antennas for TFTR

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  14. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  15. Heavy ion studies with CMS HF calorimeter

    International Nuclear Information System (INIS)

    Damgov, I.; Genchev, V.; Kolosov, V.A.; Lokhtin, I.P.; Petrushanko, S.V.; Sarycheva, L.I.; Teplov, S.Yu.; Shmatov, S.V.; Zarubin, P.I.

    2001-01-01

    The capability of the very forward (HF) calorimeter of the CMS detector at LHC to be applied to specific studies with heavy ion beams is discussed. The simulated responses of the HF calorimeter to nucleus-nucleus collisions are used for the analysis of different problems: reconstruction of the total energy flow in the forward rapidity region, accuracy of determination of the impact parameter of collision, study of fluctuations of the hadronic-to-electromagnetic energy ratio, fast inelastic event selection

  16. Frequency scanning microstrip antennas

    DEFF Research Database (Denmark)

    Danielsen, Magnus; Jørgensen, Rolf

    1979-01-01

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

  17. Metamaterial antennas: the most successful metamaterial technology?

    DEFF Research Database (Denmark)

    Breinbjerg, Olav

    2015-01-01

    The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas.......The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas....

  18. 47 CFR 73.510 - Antenna systems.

    Science.gov (United States)

    2010-10-01

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

  19. Reconfigurable antenna using plasma reflector

    Science.gov (United States)

    Jusoh, Mohd Taufik; Ahmad, Khairol Amali; Din, Muhammad Faiz Md; Hashim, Fakroul Ridzuan

    2018-02-01

    This paper presents the feasibility study and design of plasma implementation in industrial, scientific and medical (ISM) communication band. A reflector antenna with rounded shaped is proposed to collimate beam in particular direction radiated by a quarter wave antenna operating at 2.4GHz. The simulations result has shown that by using plasma as the reflector elements, the gain, directivity and radiation patterns are identical with metal elements with only small different in the broadside direction. The versatility of the antenna is achievable by introducing electrical reconfigurable option to change the beam pattern.

  20. Absorption Efficiency of Receiving Antennas

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Frandsen, Aksel

    2005-01-01

    A receiving antenna with a matched load will always scatter some power. This paper sets an upper and a lower bound on the absorption efficiency (absorbed power over sum of absorbed and scattered powers), which lies between 0 and 100% depending on the directivities of the antenna and scatter...... patterns. It can approach 100% as closely as desired, although in practice this may not be an attractive solution. An example with a small endfire array of dipoles shows an efficiency of 93%. Several examples of small conical horn antennas are also given, and they all have absorption efficiencies less than...

  1. Reconfigurable Antenna for Medical Applications

    Directory of Open Access Journals (Sweden)

    Elizabeth RUFUS

    2009-12-01

    Full Text Available Microwave imaging systems offer much promise for biomedical applications such as cancer detection because of their good penetration, non invasive and non ionizing nature and low cost. The resolution is one of the major problems faced in such systems, which can be improved by applying signal processing techniques. The key element for the microwave imaging system is the antenna. This paper present a fractal antenna which has low profile, light weight and is easy to be fabricated. It has been successfully demonstrated to have multiband characteristics. The simulated results show that the proposed antenna has very good radiation characteristics suitable for imaging applications.

  2. Large inflated-antenna system

    Science.gov (United States)

    Hinson, W. F.; Keafer, L. S.

    1984-01-01

    It is proposed that for inflatable antenna systems, technology feasibility can be demonstrated and parametric design and scalability (scale factor 10 to 20) can be validated with an experiment using a 16-m-diameter antenna attached to the Shuttle. The antenna configuration consists of a thin film cone and paraboloid held to proper shape by internal pressure and a self-rigidizing torus. The cone and paraboloid would be made using pie-shaped gores with the paraboloid being coated with aluminum to provide reflectivity. The torus would be constructed using an aluminum polyester composite that when inflated would erect to a smooth shell that can withstand loads without internal pressure.

  3. Determination of the rate of HF hydration and the effects of HF on moisture condensation

    International Nuclear Information System (INIS)

    McCulla, W.H.

    1982-01-01

    There were four basic questions addressed in this report that relate to the HF interaction in the environment. As to whether HF hydrates in the vapor phase and what the rate of that hydration is, there seems ample evidence that HF hydrates readily in the vapor phase and the rate of that hydration is very fast, i.e., dHF/dt greater than or equal to 25 torr sec -1 . Concerning under what conditions condensation of the hydrate will occur and whether a third body is required for condensation, it was found that HF does effect the dew point or condensation of water and data was presented indicating the extent of that effect. It was also determined that condensation will occur without a third body present. Thus, in attempting to model an HF release for the Safety Analysis Report the hydration of HF and the subsequent heat released may be treated as occurring instantaneously; but the ultimate disposition of the HF will be strongly dependent upon the environmental conditions at the time of the release

  4. Determination of the rate of HF hydration and the effects of HF on moisture condensation

    Energy Technology Data Exchange (ETDEWEB)

    McCulla, W H

    1982-04-30

    There were four basic questions addressed in this report that relate to the HF interaction in the environment. As to whether HF hydrates in the vapor phase and what the rate of that hydration is, there seems ample evidence that HF hydrates readily in the vapor phase and the rate of that hydration is very fast, i.e., dHF/dt greater than or equal to 25 torr sec/sup -1/. Concerning under what conditions condensation of the hydrate will occur and whether a third body is required for condensation, it was found that HF does effect the dew point or condensation of water and data was presented indicating the extent of that effect. It was also determined that condensation will occur without a third body present. Thus, in attempting to model an HF release for the Safety Analysis Report the hydration of HF and the subsequent heat released may be treated as occurring instantaneously; but the ultimate disposition of the HF will be strongly dependent upon the environmental conditions at the time of the release.

  5. High-K rotational bands in {sup 174}Hf and {sup 175}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Gjoerup, N L; Sletten, G [The Niels Bohr Institute, Roskilbe (Denmark); Walker, P M [Surrey Univ., Guildford (United Kingdom). Dept. of Physics; Bentley, M A [Daresbury Lab. (United Kingdom); Cullen, D M; Sharpey-Schafer, J F; Fallon, P; Smith, G [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.

    1992-08-01

    High sensitivity experiments with {sup 48}Ca, {sup 18}O and {sup 9}Be induced reactions using the ESSA-30, TESSA-3 and NORDBALL arrays have provided extensive new information on the high spin level structures of {sup 174}Hf and {sup 175}Hf. During the series of experiments, several new bands have been found and most known bands have been extended considerably. Spin and excitation energy ranges for {sup 174}Hf are now {approx} 35 {Dirac_h} and {approx} 13 MeV, respectively, and for {sup 175}Hf ranges are {approx} 30 {Dirac_h} and {approx} 7 MeV. respectively. Several new high-K structures have been found in {sup 174}Hf and the structure of these and the already known high-K bands in both nuclei together with the new Tilted Axis Cranking approach might explain the small K-hindrances observed for K-isomers in this region. (author). 8 refs., 2 figs.

  6. Electrically floating, near vertical incidence, skywave antenna

    Science.gov (United States)

    Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

    2014-07-08

    An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

  7. Inflatable Antennas Support Emergency Communication

    Science.gov (United States)

    2010-01-01

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

  8. Better than a Whip?

    DEFF Research Database (Denmark)

    Reisch, Lucia A.; Sunstein, Cass R.; Gwozdz, Wencke

    We examine whether the populations of six European nations support the use of “health nudges” – strategies that preserve free choice but steer individuals in healthier directions. To assess approval rates for health nudges across, within, and in certain parts of these populations, we analyze...... the results of six nationally representative online surveys administered in Denmark, France, Germany, Hungary, Italy, and the UK. We find majority support for health nudges across the board but with lower approval rates in Hungary and Denmark. Our findings reveal national differences and identify conditions...... under which consumers tend to approve of nudging healthy behavior. They therefore provide policymakers with practical guidance on which health nudges are likely to receive high levels of public support in the nation states studied....

  9. Living antennas on communication satellites

    DEFF Research Database (Denmark)

    Lumholt, Michael

    2003-01-01

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

  10. Antenna design for mobile devices

    CERN Document Server

    Zhang, Zhijun

    2017-01-01

    - Integrates state-of-the-art technologies with a special section for step-by-step antenna design - Features up-to-date bio-safety and electromagnetic compatibility regulation compliance and latest standards - Newly updated with MIMO antenna design, measurements and requirements - Accessible to readers of many levels, from introductory to specialist - Written by a practicing expert who has hired and trained numerous engineers

  11. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  12. Antennas for mobile satellite communications

    Science.gov (United States)

    Huang, John

    1991-12-01

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

  13. Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

    Science.gov (United States)

    Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J. R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J. L.; Soubervielle-Montalvo, C.; Mani-Gonzalez, P. G.

    2016-06-01

    The final structure of HfO2 films grown by atomic layer deposition (ALD) after reaction with OH- ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl4 (hafnium tetrachloride), HfI4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO-H was studied employing the B3LYP (Becke 3-parameter, Lee-Yang-Parr) hybrid functional and the PBE (Perdew-Burke-Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

  15. Some Recent Developments of Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    Yong Liu

    2012-01-01

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

  16. Impact of emissions of Pridneprovsk TPP in Dnipropetrovsk on the anatomical indices of stem of two-year whip of the Tilia genus representatives

    Directory of Open Access Journals (Sweden)

    Z. V. Gritzay

    2015-09-01

    Full Text Available The paper presents discussion of the results of studying the impact of environmental contamination because of emissions of Pridneprovsk TPP in Dnipropetrovsk city on the anatomical indices of stem of two-year whip of the Tilia genus representatives. Objects of study were T. platyphyllos Scop., T. europaea L. and T. cordata Mill. Material was collected in September 2015 on two sampling areas: experimental plot – tree plantations adjacent to Pridneprovsk TPP which emissions mainly comprise the pollutants such as sulfur dioxide, nitrogen oxides, particulate matter, with the share in total volume of emissions of the Plant being 67.3%, 18.7%, 13.3%, respectively; control plot (conditionally clean – territory of the Botanical garden of Oles Honchar Dnipropetrovsk National University. For research, two-year whips located in the apical portion of branches of the same order of branching were taken. Sections were made at the medium cross-line of the stem, and stained with the alcoholic solution of phloroglucinol. 30 sections for each species were measured on each sampling area. In the objects under study on technogenically contaminated area the changes in dimensions of histological elements of the stem were found and the nature of such changes had specific differences. T. platyphyllos and T. europaea under action of toxic emissions of TPP demonstrated the increase of total size of primary cortex of stem and width of its individual components (plug, collenchyma, cortex parenchyma, maintenance of stable dimensions of the bark and its histological elements (hard and soft bast, and in T. europaea the wood radius as well, which we considered as the indicators of relative stability of these species in technogenic environment. In T. cordata in the TPP emission zone we revealed the increase in the width of plug, cortex parenchyma, and total radius of primary cortex, which could provide certain tolerance of plants of this species in the adverse conditions of

  17. Antenna for passive RFID tags

    Science.gov (United States)

    Schiopu, Paul; Manea, Adrian; Cristea, Ionica; Grosu, Neculai; Vladescu, Marian; Craciun, Anca-Ileana; Craciun, Alexandru

    2015-02-01

    Minuscule devices, called RFID tags are attached to objects and persons and emit information which positioned readers may capture wirelessly. Many methods of identification have been used, but that of most common is to use a unique serial number for identification of person or object. RFID tags can be characterized as either active or passive [1,2]. Traditional passive tags are typically in "sleep" state until awakened by the reader's emitted field. In passive tags, the reader's field acts to charge the capacitor that powers the badge and this can be a combination of antenna and barcodes obtained with SAW( Surface Acoustic Wave) devices [1,2,3] . The antenna in an RFID tag is a conductive element that permits the tag to exchange data with the reader. The paper contribution are targeted to antenna for passive RFID tags. The electromagnetic field generated by the reader is somehow oriented by the reader antenna and power is induced in the tag only if the orientation of the tag antenna is appropriate. A tag placed orthogonal to the reader yield field will not be read. This is the reason that guided manufacturers to build circular polarized antenna capable of propagating a field that is alternatively polarized on all planes passing on the diffusion axis. Passive RFID tags are operated at the UHF frequencies of 868MHz (Europe) and 915MHz (USA) and at the microwave frequencies of 2,45 GHz and 5,8 GHz . Because the tags are small dimensions, in paper, we present the possibility to use circular polarization microstrip antenna with fractal edge [2].

  18. Searching triaxial superdeformation in 175Hf

    International Nuclear Information System (INIS)

    Li Xiaowei; Zhejiang Normal Univ., Jinhua; Yu Shaoying; Zhejiang Normal Univ., Jinhua; Chinese Academy of Sciences, Beijing; Shen Caiwan; National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou; Chen Yongshou; Chinese Academy of Sciences, Beijing; National Laboratory of Heavy Ion Accelerator of Lanzhou

    2006-01-01

    A two-dimensional Total Routhian Surface (TRS) calculation is carried out in order to ascertain if there is triaxial superdeformation in 175 Hf. A five quasi-particle configuration is chosen in the calculation. Unfortunately, the TRS minimum does not show up in the total potential energy surface. (authors)

  19. Ferromagnetic characteristics of HfFe2

    International Nuclear Information System (INIS)

    Novakovic, N.; Belosevic-Cavor, J.; Cekic, B.; Manasijevic, M.; Milosevic, Z. . E-mail address of correspoding author: novnik@rt270.vin.bg.ac.yu; Novakovic, N.)

    2003-01-01

    The magnetic hyperfine fields at 181 Ta ion-probe sites in the HfFe 2 polycrystalline binary compound were measured using the time-differential perturbed angular correlation (TDPAC) method. Measurements were performed in the absence of polarizing external magnetic field, at room temperature. The existence of two different structures, dominant cubic MgCu 2 -type and hexagonal MgZn 2 -type in our HfFe 2 sample was refined. Both structures are ferromagnetic with Curie temperatures, which differ significantly (588 K for MgCu 2 and 427 K for MgZn 2 ). The corresponding values of hyperfine fields are H hf 13.8±0.1 T for MgCu 2 -type structure and H hf = 8.0±0.2 T for MgZn 2 -type structure. Calculations using LAPW-Wien 97 program package are in progress and preliminary results are in good agreement with experiment. The analysis includes qualitative explanation of the exchange interactions mechanism between magnetic dipole moment of the observed 181 Ta ion-probe and magnetic dipole moments of the nearest neighbours on the corresponding coordination polyhedra. All these results will be published recently. (author)

  20. Statistical gamma transitions in {sup 174}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Farris, L P; Cizewski, J A; Brinkman, M J; Henry, R G; Lee, C S [Rutgers--the State Univ., New Brunswick, NJ (United States); Khoo, T L; Janssens, R V.F.; Moore, E F; Carpenter, M P; Ahmad, I; Lauritsen, T [Argonne National Lab., IL (United States); Kolata, J J; Beard, K B; Ye, B; Garg, U [Notre Dame Univ., IN (United States); Kaplan, M S; Saladin, J X; Winchell, D [Pittsburgh Univ., PA (United States)

    1992-08-01

    The statistical spectrum extracted from the {sup 172}Yb({alpha},2n){sup 174}Hf reaction was fit with Monte Carlo simulations using a modified GDR E1 strength function and several formulations of the level density. (author). 15 refs., 1 tab., 3 figs.

  1. Modern lens antennas for communications engineering

    CERN Document Server

    Thornton, John

    2012-01-01

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

  2. Antenna Miniaturization with MEMS Tunable Capacitors

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  3. Design of LTCC Based Fractal Antenna

    KAUST Repository

    AdbulGhaffar, Farhan

    2010-09-01

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

  4. QAPP for Hydraulic Fracturing (HF) Surface Spills Data Analysis

    Science.gov (United States)

    This QAPP provides information concerning the analysis of spills associated with hydraulic fracturing. This project is relevant to both the chemical mixing and flowback and produced water stages of the HF water cycle as found in the HF Study Plan.

  5. SEMICONDUCTOR TECHNOLOGY: Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    Science.gov (United States)

    Yongliang, Li; Qiuxia, Xu

    2010-03-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 °C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case.

  6. Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

    International Nuclear Information System (INIS)

    Li Yongliang; Xu Qiuxia

    2010-01-01

    The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 0 C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N 2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case. (semiconductor technology)

  7. Radio tomography and scintillation studies of ionospheric electron density modification caused by a powerful HF-wave and magnetic zenith effect at mid-latitudes

    International Nuclear Information System (INIS)

    Tereshchenko, E.D.; Khudukon, B.Z.; Gurevich, A.V.; Zybin, K.P.; Frolov, V.L.; Myasnikov, E.N.; Muravieva, N.V.; Carlson, H.C.

    2004-01-01

    Observations of the ionospheric electron density modified by a powerful wave of the Sura HF heating facility were carried out in Russia at middle latitudes in August 2002. Amplitude scintillations and variations of the phase of VHF signals from Russian orbiting satellites passing over the heated region along the chain of three satellite receivers have been recorded. The experimental data were converted to electron density maps using a stochastic inversion. Tomographic measurements conducted during a low magnetic activity revealed that HF powerful waves can produce significant electron density disturbances up to heights significantly exceeding altitudes of the F layer peak. Both large-scale plasma enhancements and small-scale density irregularities can be generated by the HF radiation. Wavy density structures were also observed within a sector which is much wider than the area covered by the main lobe of the heating antenna. Small-scale density irregularities are mostly field-aligned although large-scale structures can be detected within a much larger area. A distinctive peculiarity of electron density changes occurred during heating is producing a zone of low density inside the area illuminated by the antenna beam. The results indicate that satellite radio tomography and scintillation measurements are effective diagnostic techniques giving a valuable information to studies of effects induced by HF modification. The complete system of plasma density disturbances describing by the theory of 'the magnetic zenith effect' has been for the first time studied in this Letter. A good agreement between the theory and experimental data has been obtained

  8. Compact Low Frequency Radio Antenna

    Science.gov (United States)

    Punnoose, Ratish J.

    2008-11-11

    An antenna is disclosed that comprises a pair of conductive, orthogonal arches and a pair of conductive annular sector plates, wherein adjacent legs of each arch are fastened to one of the annular sector plates and the opposite adjacent pair of legs is fastened to the remaining annular sector plate. The entire antenna structure is spaced apart from a conductive ground plane by a thin dielectric medium. The antenna is driven by a feed conduit passing through the conductive ground plane and dielectric medium and attached to one of the annular sector plates, wherein the two orthogonal arched act as a pair of crossed dipole elements. This arrangement of elements provides a radiation pattern that is largely omni-directional above the horizon.

  9. Biogenic Amines in Insect Antennae

    Directory of Open Access Journals (Sweden)

    Marianna I. Zhukovskaya

    2017-06-01

    Full Text Available Insect antenna is a multisensory organ, each modality of which can be modulated by biogenic amines. Octopamine (OA and its metabolic precursor tyramine (TA affect activity of antennal olfactory receptor neurons. There is some evidence that dopamine (DA modulates gustatory neurons. Serotonin can serve as a neurotransmitter in some afferent mechanosensory neurons and both as a neurotransmitter and neurohormone in efferent fibers targeted at the antennal vessel and mechanosensory organs. As a neurohormone, serotonin affects the generation of the transepithelial potential by sensillar accessory cells. Other possible targets of biogenic amines in insect antennae are hygro- and thermosensory neurons and epithelial cells. We suggest that the insect antenna is partially autonomous in the sense that biologically active substances entering its hemolymph may exert their effects and be cleared from this compartment without affecting other body parts.

  10. Hf layer thickness dependence of resistive switching characteristics of Ti/Hf/HfO2/Au resistive random access memory device

    Science.gov (United States)

    Nakajima, Ryo; Azuma, Atsushi; Yoshida, Hayato; Shimizu, Tomohiro; Ito, Takeshi; Shingubara, Shoso

    2018-06-01

    Resistive random access memory (ReRAM) devices with a HfO2 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. Furthermore, it was reported that a thin Hf layer next to a HfO2 layer stabilized switching properties because of the oxygen scavenging effect. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/HfO2/Au ReRAM device. It is found that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current. However, when the Hf thickness was very small (∼2 nm), the device failed after the first RESET process owing to the very large RESET current. In the case of a very thick Hf layer (∼20 nm), RESET did not occur owing to the formation of a leaky dielectric layer. We observed the occurrence of multiple resistance states in the RESET process of the device with a Hf thickness of 10 nm by increasing the RESET voltage stepwise.

  11. Design of LTCC Based Fractal Antenna

    KAUST Repository

    AdbulGhaffar, Farhan

    2010-01-01

    The thesis presents a Sierpinski Carpet fractal antenna array designed at 24 GHz for automotive radar applications. Miniaturized, high performance and low cost antennas are required for this application. To meet these specifications a fractal array

  12. Wireless interrogation of passive antenna sensors

    International Nuclear Information System (INIS)

    Deshmukh, S; Huang, H

    2010-01-01

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

  13. Statistical monitoring of linear antenna arrays

    KAUST Repository

    Harrou, Fouzi; Sun, Ying

    2016-01-01

    The paper concerns the problem of monitoring linear antenna arrays using the generalized likelihood ratio (GLR) test. When an abnormal event (fault) affects an array of antenna elements, the radiation pattern changes and significant deviation from

  14. Accurate determination of antenna directivity

    DEFF Research Database (Denmark)

    Dich, Mikael

    1997-01-01

    The derivation of a formula for accurate estimation of the total radiated power from a transmitting antenna for which the radiated power density is known in a finite number of points on the far-field sphere is presented. The main application of the formula is determination of directivity from power......-pattern measurements. The derivation is based on the theory of spherical wave expansion of electromagnetic fields, which also establishes a simple criterion for the required number of samples of the power density. An array antenna consisting of Hertzian dipoles is used to test the accuracy and rate of convergence...

  15. Mobile Phone Antenna Performance 2016

    DEFF Research Database (Denmark)

    Pedersen, Gert F.

    This study investigates the antenna performance of a number of mobile phones widely used in the Nordic Countries. The study is supported by the Nordic Council of Ministers. The antenna performance of the phones is vital for the phones ability to ensure radio coverage in low signal situations....... The study is based on the mobile systems in the Nordic mobile networks and on both speech and data services. The selected phone models are among the most popular new phones at the time of this study....

  16. Estimation of complex permittivity using loop antenna

    DEFF Research Database (Denmark)

    Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

    2004-01-01

    A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna.......A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna....

  17. System and circuit models for microwave antennas

    OpenAIRE

    Sobhy, Mohammed; Sanz-Izquierdo, Benito; Batchelor, John C.

    2007-01-01

    This paper describes how circuit and system models are derived for antennas from measurement of the input reflection coefficient. Circuit models are used to optimize the antenna performance and to calculate the radiated power and the transfer function of the antenna. System models are then derived for transmitting and receiving antennas. The most important contribution of this study is to show how microwave structures can be integrated into the simulation of digital communication systems. Thi...

  18. Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

    International Nuclear Information System (INIS)

    Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J.R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J.L.

    2016-01-01

    Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO 2 films grown by atomic layer deposition (ALD) after reaction with OH − ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl 4 (hafnium tetrachloride), HfI 4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  19. Comparison of HfCl{sub 4}, HfI{sub 4}, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO{sub 2} films deposited by ALD: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Cortez-Valadez, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Fierro, C.; Farias-Mancilla, J.R. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); Vargas-Ortiz, A. [Universidad Autónoma de Sinaloa, Facultad de Ingeniería Mochis, Ciudad Universitaria, C.P. 81223 Los Mochis, Sinaloa (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190 Hermosillo, Son. (Mexico); Ramírez-Bon, R. [Centro de Investigación y Estudios Avanzados del IPN, Unidad Querétaro, Apdo. Postal 1-798, 76001 Querétaro, Qro. (Mexico); Enriquez-Carrejo, J.L. [Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. del Charro 450, Cd. Juárez C.P. 32310, Chihuahua (Mexico); and others

    2016-06-15

    Highlights: • Hafnium oxide growth on Si(100) by atomic layer deposition was simulated. • The interface structure was considered as silicate and silicide. • The interface was studied employing DFT. • TDMA-Hf precursor show better interface stability. - Abstract: The final structure of HfO{sub 2} films grown by atomic layer deposition (ALD) after reaction with OH{sup −} ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl{sub 4} (hafnium tetrachloride), HfI{sub 4} (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO–H was studied employing the B3LYP (Becke 3-parameter, Lee–Yang–Parr) hybrid functional and the PBE (Perdew–Burke–Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  20. Numerical Study of Planar GPR Antenna Measurements

    DEFF Research Database (Denmark)

    Meincke, Peter; Hansen, Thorkild

    2004-01-01

    The formulation of planar near-field measurements of GPR antennas determines the plane-wave spectra of the GPR antenna in terms of measurements obtained with a buried probe as the GPR antenna moves over a scan plane on the ground. A numerical study investigates how the formulation is affected by (1...

  1. Theory of antennas for gravitational radiation

    International Nuclear Information System (INIS)

    Hirakawa, Hiromasa; Narihara, Kazumichi; Fujimoto, Masakatsu.

    1976-01-01

    A theory of antennas for gravitational radiation is presented. On the basis of the eigenmode system and the structure symmetry, the emission and reception characteristics and the directivity pattern of antennas are treated. The antenna thermal noise is discussed in connection with the coupling constant of vibration sensors and with the effect of cold-damping. (auth.)

  2. 47 CFR 78.105 - Antenna systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 78.105 Section 78.105... SERVICE Technical Regulations § 78.105 Antenna systems. (a) For fixed stations operating in the 12.7-13.2... planes. (2) New periscope antenna systems will be authorized upon a certification that the radiation, in...

  3. 47 CFR 74.641 - Antenna systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 74.641 Section 74.641... Stations § 74.641 Antenna systems. (a) For fixed stations operating above 2025 MHz, the following standards... elevation planes. (2) New periscope antenna systems will be authorized upon a certification that the...

  4. Collapsible structure for an antenna reflector

    Science.gov (United States)

    Trubert, M. R. (Inventor)

    1973-01-01

    A collapsible support for an antenna reflector for use in supporting spacecraft antennas is described. The support has a regid base and a number of struts which are pivoted at the base. The deployment of the struts and their final configuration for supporting the antenna are illustrated.

  5. Inflatable antenna for earth observing systems

    Science.gov (United States)

    Wang, Hong-Jian; Guan, Fu-ling; Xu, Yan; Yi, Min

    2010-09-01

    This paper describe mechanical design, dynamic analysis, and deployment demonstration of the antenna , and the photogrammetry detecting RMS of inflatable antenna surface, the possible errors results form the measurement are also analysed. Ticra's Grasp software are used to predict the inflatable antenna pattern based on the coordinates of the 460 points on the parabolic surface, the final results verified the whole design process.

  6. Adaptive Nulling in Hybrid Reflector Antennas

    Science.gov (United States)

    1992-09-01

    correction of reflector distortion and vernier beamsteering, MEEE Trans. Antennas Propagat, 36:1351-1358. 4 Cherrette , A.R., et al (1989) Compensation of...Propagat, 36:1351-1358. 4. Cherrette , A.R., et al (1989) Compensation of reflector antenna surface distortion using an array feed,IEEE Trans. Antennas

  7. Fundamentals of antennas concepts and applications

    CERN Document Server

    Christodoulou, Christos G

    2001-01-01

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

  8. Self-diffusion of Er and Hf inpure and HfO2-doped polycrystalline Er2O3

    International Nuclear Information System (INIS)

    Scheidecker, R.W.

    1979-01-01

    Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970 0 C in pure and HfO 2 -doped polycryatalline Er 2 O 3 . Up to about 10 m/o HfO 2 dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO 2 , deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er 2 O 3 was 82.2 Kcal/mole and increased with the HfO 2 dopant level present. Self-diffusion of Hf was measured in pure Er 2 O 3 having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er 2 O 3 . The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO 2 doped Er 2 O 3 compositions. Despite a clustering effect, the HfO 2 dopant increased the Hf volume diffusion coefficients

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

    DEFF Research Database (Denmark)

    Cappellin, Cecilia; Frandsen, Aksel; Breinbjerg, Olav

    2008-01-01

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

  10. High resolution TDPAC measurements on 181Ta in Hf2Fe, Hf2Co and Hf2Rh at high temperature

    International Nuclear Information System (INIS)

    Cekic, B.; Koicki, S.; Ivanovic, N.; Manasijevic, M.; Koteski, V.; Marjanovic, D.

    1998-01-01

    The time differential perturbed angular correlation measurements (TDPAC-method ) on 181 Ta ion probe in Hf 2 Co, Hf 2 Fe and Hf 2 Rh intermetallic compounds have been performed at 1170 K, using a fast - slow time spectrometer consisting of two BaF 2 detectors. The results of the measurements show the presence of two independent electric quadrupole interactions, compatible with the crystalline structure of these polycrystalline compounds. (authors)

  11. The Antenna Bride and Bridegroom

    Science.gov (United States)

    2007-03-01

    ALMA Achieves Major Milestone With Antenna-Link Success The Atacama Large Millimeter/submillimeter Array (ALMA), an international telescope project, reached a major milestone on 2 March, when two 12-m ALMA prototype antennas were first linked together as an integrated system to observe an astronomical object. "This achievement results from the integration of many state-of-the-art components from Europe and North America and bodes well for the success of ALMA in Chile", said Catherine Cesarsky, ESO's Director General. ESO PR Photo 10/07 ESO PR Photo 10/07 The Prototype Antennas The milestone achievement, technically termed 'First Fringes', came at the ALMA Test Facility (ATF), located near Socorro in New Mexico. Faint radio waves emitted by the planet Saturn were collected by two ALMA prototype antennas, then processed by new, high-tech electronics to turn the two antennas into a single, high-resolution telescope system, called an interferometer. The planet's radio emissions at a frequency of 104 gigahertz were tracked by the ALMA system for more than an hour. Such pairs of antennas are the basic building blocks of the multi-antenna imaging system ALMA. In such a system, the signals recorded by each antenna are electronically combined with the signals of every other antenna to form a multitude of pairs. Each pair contributes unique information that is used to build a highly detailed image of the astronomical object under observation. When completed in the year 2012, ALMA will have 66 antennas. "Our congratulations go to the dedicated team of scientists, engineers and technicians who produced this groundbreaking achievement for ALMA. Much hard work and many long hours went into this effort, and we appreciate it all. This team should be very proud today," said NRAO Director Fred K.Y. Lo. "With this milestone behind us, we now can proceed with increased confidence toward completing ALMA," he added. ALMA, located at an elevation of 5,000m in the Atacama Desert of

  12. Photogrammetry Of A Parabolic Antenna

    Science.gov (United States)

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

    1988-01-01

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

  13. Tunable Antennas for Mobile Devices

    DEFF Research Database (Denmark)

    Morris, Art; Barrio, Samantha Caporal Del; Shin, J

    2014-01-01

    Modern mobile terminal design has been driven by the user interface and broadband connectivity. Real world RF performance has substantially fallen recently which impacts data rates, battery life and often causes lost connections. This has been caused by changing antenna location and reduced anten...

  14. Wireless Communication with Multiple Antennas

    Indian Academy of Sciences (India)

    2013-07-05

    Emre Telatar, “Capacity of Multi-antenna Gaussian Channels,” European. Transactions on Telecommunications, vol.10, No.6, pp.585-595, 1999. Similar diminishing-return behaviour with M fixed. B. Sundar Rajan (ECE). IASc Talk ...

  15. Coupling between minimum scattering antennas

    DEFF Research Database (Denmark)

    Andersen, J.; Lessow, H; Schjær-Jacobsen, Hans

    1974-01-01

    Coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn. Only rotationally symmetric power patterns are considered, and graphs of relative mutual impedance are presented as a function of distance and pattern parameters. Crossed...

  16. Theory of the JET ICRH antenna

    International Nuclear Information System (INIS)

    Theilhaber, K.

    1984-01-01

    The JET antenna has been conceived as a 'limiter antenna', completely recessed in a lateral frame which has the dual purpose of protecting the conductors and limiting the plasma radius. The coupling of this antenna is calculated in slab geometry, using a variational formulation which finds the self-consistent currents in the antenna elements. Full account is taken of the modes excited inside the limiter frame and of their coupling to waves in the inhomogeneous plasma. This yields the antenna impedance as a function of frequency and the field structure inside the plasma, including power fluxes and dispersion, as a function of penetration. (author)

  17. Microstrip Antenna Design for Femtocell Coverage Optimization

    Directory of Open Access Journals (Sweden)

    Afaz Uddin Ahmed

    2014-01-01

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

  18. Forward Scattering of Loaded and Unloaded Antennas

    DEFF Research Database (Denmark)

    Gustafsson, Mats; Andersen, Jørgen Bach; Kristensson, Gerhard

    2012-01-01

    Forward scattering of antennas is related to antenna performance via the forward-scattering sum rule. The forward-scattering sum rule is an integral identity that shows that a weighted integral of the extinction cross section over all spectrum is proportional to the static polarizability...... of the antenna structure. Here, the forward-scattering sum rule is experimentally verified for loaded, short-circuit, and open-circuit cylindrical dipole antennas. It is also shown that the absorption efficiency cannot be greater than 1/2 for reciprocal linearly polarized lossless matched antennas...... with a symmetric radiation pattern in the forward and backward directions....

  19. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

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

  20. Miniaturized Planar Split-Ring Resonator Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2009-01-01

    on how small this antenna can be. In practice, the lower bound is set by losses in utilized materials and manufacturing inaccuracies. As an example, an antenna of ka=0.09 was designed, fabricated and tested. Although the initially fabricated antenna prototype had the input impedance of 43 ohms......, it was subsequently tuned to 50 ohms simply by cutting out the excessive arm length. This tuning technique is especially useful in practical applications, since it allows the antenna to be tuned in-place and thereby compensate for various inaccuracies as well as for an antenna environment....

  1. COMWIN Antenna System Fiscal Year 2000 Report

    National Research Council Canada - National Science Library

    Adams, R

    2000-01-01

    .... The Joint Tactical Radio (JTR) requires this frequency. The figure of merit to determine whether the radio is efficient in the band is a Standing Wave Ratio (VSWR) of less than 3:1. The COMWIN antenna system would consist of three antennas. The first antenna, in the form of a vest, would operate in the 30- to 500-MHz band. The helmet antenna would operate in the 500- to 2000 MHz band. An antenna that runs down the edges would operate in the 2- to 30-MHz band.

  2. Measurement of Antenna Bore-Sight Gain

    Science.gov (United States)

    Fortinberry, Jarrod; Shumpert, Thomas H.

    2016-01-01

    The absolute or free-field gain of a simple antenna can be approximated using standard antenna theory formulae or for a more accurate prediction, numerical methods may be employed to solve for antenna parameters including gain. Both of these methods will result in relatively reasonable estimates but in practice antenna gain is usually verified and documented via measurements and calibration. In this paper, a relatively simple and low-cost, yet effective means of determining the bore-sight free-field gain of a VHF/UHF antenna is proposed by using the Brewster angle relationship.

  3. Benchmark simulations of ICRF antenna coupling

    International Nuclear Information System (INIS)

    Louche, F.; Lamalle, P. U.; Messiaen, A. M.; Compernolle, B. van; Milanesio, D.; Maggiora, R.

    2007-01-01

    The paper reports on ongoing benchmark numerical simulations of antenna input impedance parameters in the ion cyclotron range of frequencies with different coupling codes: CST Microwave Studio, TOPICA and ANTITER 2. In particular we study the validity of the approximation of a magnetized plasma slab by a dielectric medium of suitably chosen permittivity. Different antenna models are considered: a single-strap antenna, a 4-strap antenna and the 24-strap ITER antenna array. Whilst the diagonal impedances are mostly in good agreement, some differences between the mutual terms predicted by Microwave Studio and TOPICA have yet to be resolved

  4. Design of broadband single polarized antenna

    Science.gov (United States)

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

    2015-05-01

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

  5. Group Delay of High Q Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert Frølund

    2013-01-01

    Group Delay variations versus frequency is an essential factor which can cause distortion and degradation in the signals. Usually this is an issue in wideband communication systems, such as satellite communication systems, which are used for transmitting wideband data. However, group delay can also...... become an issue, when working with high Q antennas, because of the steep phase shift over the frequency. In this paper, it is measured how large group delay variations can become, when going from a low Q antenna to a high Q antenna. The group delay of a low Q antenna is shown to be around 1.3 ns, whereas...... a high Q antenna has group delay of around 22 ns. It is due to this huge group delay variation characteristics of high Q antennas, that signal distortion might occur in the radio system with high Q antennas....

  6. SKB - PNC. Development of tunnel radar antennas

    International Nuclear Information System (INIS)

    Falk, L.

    1991-07-01

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

  7. Improvement of antenna decoupling in radar systems

    Science.gov (United States)

    Anchidin, Liliana; Topor, Raluca; Tamas, Razvan D.; Dumitrascu, Ana; Danisor, Alin; Berescu, Serban

    2015-02-01

    In this paper we present a type of antipodal Vivaldi antenna design, which can be used for pulse radiation in UWB communication. The Vivaldi antenna is a special tapered slot antenna with planar structure which is easily to be integrated with transmitting elements and receiving elements to form a compact structure. When the permittivity is very large, the wavelength of slot mode is so short that the electromagnetic fields concentrate in the slot to form an effective and balanced transmission line. Due to its simple structure and small size the Vivaldi antennas are one of the most popular designs used in UWB applications. However, for a two-antenna radar system, there is a high mutual coupling between two such antennas due to open configuration. In this paper, we propose a new method for reducing this effect. The method was validated by simulating a system of two Vivaldi antennas in front of a standard target.

  8. Magnetic properties of Hf177 and Hf180 in the strong-coupling deformed model

    Science.gov (United States)

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.; Walters, W. B.

    2014-04-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2-, 51.4 m, 2740 keV state in Hf177 and the 8-, 5.5 h, 1142 keV state in Hf180 by the method of on-line nuclear orientation. Also included are results on the angular distributions of γ transitions in the decay of the Hf177 isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2+, 1.1 s, isomer at 1315 keV and on the 9/2+, 0.663 ns, isomer at 321 keV. The new results are discussed in the light of the recently reported finding of systematic dependence of the behavior of the gR parameter upon the quasiproton and quasineutron make up of high-K isomeric states in this region.

  9. Electric Field Gradients at Hf and Fe Sites in Hf2Fe Recalculated

    International Nuclear Information System (INIS)

    Belosevic-Cavor, J.; Cekic, B.; Novakovic, N.; Koteski, V.; Milosevic, Z.

    2004-01-01

    The electric field gradients (EFG) of the Hf 2 Fe intermetallic compound were calculated using the full-potential linearized augmented plain-wave (FP-LAPW) method as embodied in the WIEN 97 code. The obtained values are compared with other ab-initio calculations and on a qualitative basis with the previously reported experimental data obtained from TDPAC. The calculated results, -23.1.10 21 V/m 2 and 2.7.10 21 V/m 2 for Hf 48f and Fe 32e position, respectively, are in excellent agreement with experimental data (23.4.10 21 V/m 2 and 2.7.10 21 V/m 2 ), better than those reported in earlier calculations. The calculated EFG for Hf 16c position (4.2.10 21 V/m 2 ) is stronger than the experimental one (1.1.10 21 V/m 2 ).

  10. Lifetime of the first excited 2{sup +} state in {sup 172}Hf and {sup 174}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Gerst, Rosa-Belle; Stegemann, Simon; Jolie, Jan; Regis, Jean-Marc; Rudigier, Matthias; Saed-Samii, Nima; Zell, Karl Oskar [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

    2014-07-01

    Using the {sup 170}Yb(α,2n) and {sup 172}Yb(α,2n) reactions the lifetimes of the first excited 2{sup +} state in {sup 172}Hf and {sup 174}Hf have been measured in fast-timing experiments using the Cologne Orange-Spectrometer and 6 LaBr{sub 3}(Ce)-Detectors. The lifetimes were obtained analyzing e{sup -}-γ-coincidence time-spectra with the slope method. The new and more precise lifetimes correct existing, outdated lifetimes in nuclear databases. Additionally, the systematics of the B(E2,2{sub 1}{sup +}→0{sub 1}{sup +}) is studied.

  11. Search for chemical separations of the element 106 homologues in HF and HF-HCl media

    International Nuclear Information System (INIS)

    Trubert, D.; Monroy-Guzman, F.; Hussonnois, M.; Brillard, L.; Le Naour, C.; Constantinescu, O.

    1996-01-01

    In order to study the chemical properties of element 263 106 in aqueous media, fast, efficient and reproducible chromatographic separations were tested on its assumed homologous: Mo, W and U. Corroborative static and dynamic off-line experiments have shown that after fixation of these three elements on anion-exchange resin in HF medium, selective elution could be achieved by using suitable concentration of HCl - HF and HCl solutions. Separations of short-lived W isotopes, produced through heavy ion irradiation were also performed on-line. (author). 27 refs., 14 figs

  12. Investigation of HF-plasma-treated soft x-ray optical elements

    Science.gov (United States)

    Eggenstein, F.; Krivenkov, M.; Rudolph, I.; Sertsu, M. G.; Sokolov, A.; Varykhalov, A.; Wolf, J.; Zeschke, T.; Schäfers, F.

    2017-09-01

    The contamination of optical elements (mirrors and gratings) with carbon still is an issue when using soft x-ray synchrotron radiation. With an in-house developed HF-plasma treatment we are able to decontaminate our optics in-situ from carbon very efficiently. The cleaning device, a simple Al-antenna, is mounted in situ inside the mirror- and grating vacuum chambers. A systematic study of the HF-plasma cleaning efficiency was performed acquired with in-situ and exsitu methods for monitoring: An atomic force microscope (AFM) and a scanning tunneling microscope (STM) were used before and after the cleaning process to determine the surface morphology and roughness. Reflectivity angular scans using the reflectometer at the BESSY-II Metrology Station [1-3] allowed to estimate the thickness of the remaining Clayer after different cleaning steps and thereby helped us to determine the etching rate. Reflection spectra measurements in the range of 200 eV - 900 eV show the complete removal of Carbon from the optics without contaminating it with any other elements due to the plasma treatment. The data show that the plasma process improves the reflectivity and reduces the roughness of the surface. In addition to that, the region of the optical surface where the carbon has been removed becomes passivated.

  13. HF Radio Astronomy from a Small Satellite

    Science.gov (United States)

    2016-06-15

    SSC16-XI-03 HF Radio Astronomy from a Small Satellite Frank C. Robey1, Mary Knapp2, Alan J. Fenn1, Mark Silver1, Kerry Johnson1 Frank J. Lind3...frequency end of the electromagnetic spectrum (below 15 MHz) is one of the least explored windows in observational astronomy . Observations at these...pdf. [Accessed: 17-Oct-2015]. 3. G. Hallinan, “The Owens Valley LWA,” in Exascale Radio Astronomy , 2014, vol. 2. 4. C. J. Lonsdale, R. J. Cappallo

  14. Antenna Arrays and Automotive Applications

    CERN Document Server

    Rabinovich, Victor

    2013-01-01

    This book throws a lifeline to designers wading through mounds of antenna array patents looking for the most suitable systems for their projects. Drastically reducing the research time required to locate solutions to the latest challenges in automotive communications, it sorts and systematizes material on cutting-edge antenna arrays that feature multi-element communication systems with enormous potential for the automotive industry. These new systems promise to make driving safer and more efficient, opening up myriad applications, including vehicle-to-vehicle traffic that prevents collisions, automatic toll collection, vehicle location and fine-tuning for cruise control systems. This book’s exhaustive coverage begins with currently deployed systems, frequency ranges and key parameters. It proceeds to examine system geometry, analog and digital beam steering technology (including "smart" beams formed in noisy environments), maximizing signal-to-noise ratios, miniaturization, and base station technology that ...

  15. High-aspect-ratio HfC nanobelts accompanied by HfC nanowires: Synthesis, characterization and field emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Song, E-mail: tiansong22@126.com [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Li, Hejun, E-mail: lihejun@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China)

    2017-04-30

    Highlights: • HfC naobelts accompanied by HfC nanowires were synthesized by a catalytic CVD method. • HfC nanobelts as a novel structure of HfC ceramic are reported for the first time. • HfC nanobelts have 100–200 μm in lengths and reach up to 10 μm in widths. • The synthesized product is promising field nanoemitters. - Abstract: As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor–liquid–solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO{sub 2} shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm{sup −1} and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications.

  16. Broadband Cylindrical Antenna and Method

    Science.gov (United States)

    2016-07-27

    May 2017 The below identified patent application is available for licensing. Requests for information should be addressed to: TECHNOLOGY...CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0002] None. BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The present invention is...Slotted cylinder antennas have been proposed in submarine applications before. For example, in U.S. Patent No. 6,127,983, Rivera and Josypenko disclose

  17. Miniaturization of Spherical Magnetodielectric Antennas

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle

    ; Arbitrary order of the spherical wave, arbitrary radius of the spherical antenna, as well as arbitrarily large core permeability and/or permittivity, given an inversely proportional frequency variation of the imaginary part(s) and an arbitrary dispersion of the real part(s) - thus describing both lossless...... with a magnetic loss tangent of 1 and relative permeability of 300 yield Q/e equal 65% of the Chu lower bound, with a simultaneous e of 71%....

  18. Hybrid Maritime Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst

    Hybrid antennas for a maritime satellite communication terminal with simultaneous operation at L- and Ka-band have been investigated. The frequency bands of interest are 1; 525:0 1; 660:5 MHz (RX+TX, RHCP), 19:7 20:2 (RX, LHCP) and 29:5 30:0 GHz (TX, RHCP), which are all part of the Inmarsat BGAN...

  19. Band-notched spiral antenna

    Science.gov (United States)

    Jeon, Jae; Chang, John

    2018-03-13

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

  20. Ab initio theoretical study of dipole-bound anions of molecular complexes: (HF)3- and (HF)4- anions

    Science.gov (United States)

    Ramaekers, Riet; Smith, Dayle M. A.; Smets, Johan; Adamowicz, Ludwik

    1997-12-01

    Ab initio calculations have been performed to determine structures and vertical electron detachment energy (VDE) of the hydrogen fluoride trimer and tetramer anions, (HF)3- and (HF)4-. In these systems the excess electron is bound by the dipole field of the complex. It was determined that, unlike the neutral complexes which prefer the cyclic structures, the equilibrium geometries of the anions have "zig-zag" shapes. For both complexes the predicted VDEs are positive [210 meV and 363 meV for (HF)3- and (HF)4-, respectively], indicating that the anions are stable systems with respect to the vertical electron detachment. These results were obtained at the coupled-cluster level of theory with single, double and triple excitations [CCSD(T) method; the triple-excitation contribution in this method is calculated approximately using the perturbation approach] with the anion geometries obtained using the second-order Møller-Plesset perturbation theory (MP2) method. The same approach was also used to determine the adiabatic electron affinities (AEA) of (HF)3 and (HF)4. In addition to the electronic contribution, we also calculated the contributions (using the harmonic approximation) resulting from different zero-point vibration energies of the neutral and anionic clusters. The calculations predicted that while the AEA of (HF)3 is positive (44 meV), the AEA for (HF)4 is marginally negative (-16 meV). This suggests that the (HF)3- anion should be a stable system, while the (HF)4- is probably metastable.

  1. Thermoelectric properties of doped BaHfO_3

    International Nuclear Information System (INIS)

    Dixit, Chandra Kr.; Bhamu, K. C.; Sharma, Ramesh

    2016-01-01

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO_3 by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO_3 doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO_3 is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO_3 is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  2. Nuclear quadrupole interactions in ferroelectric compounds of HF181

    International Nuclear Information System (INIS)

    Kunzler, J.V.

    1971-01-01

    Measurements of nuclear quadrupole interaction constants in perovkite-type compounds of PbHfO 3 , SnhfO 3 , CaHfO 3 e SrHfO 3 have been performed using the perturbed angular correlation technique. A range of fundamental frequencies from 150 to 550 Megaradians persecond was determined. The variation of quadrupole constants has been discussed through the molecular orbital theory

  3. Application of HF Radar in Hazard Management

    Directory of Open Access Journals (Sweden)

    Mal Heron

    2016-01-01

    Full Text Available A review is given of the impact that HF radars are having on the management of coastal hazards. Maps of surface currents can be produced every 10–20 minutes which, in real time, improve navigation safety in restricted areas commonly found near ports and harbours. The time sequence of surface current maps enables Lagrangian tracking of small parcels of surface water, which enables hazard mitigation in managing suspended sediments in dredging, in emergency situations where flotsam and other drifting items need to be found, and in pollution control. The surface current measurement capability is used to assist tsunami warnings as shown by the phased-array data from Chile following the Great Tohoku Earthquake in 2011. The newly launched Tsunami Warning Center in Oman includes a network of phased-array HF radars to provide real-time tsunami monitoring. Wind direction maps can be used to locate the position of cold fronts in the open ocean and to monitor the timing and strength of sea-breeze fronts in key locations.

  4. Layout Of Antennas And Cables In A Large Array

    Science.gov (United States)

    Logan, Ronald T., Jr.

    1995-01-01

    Layout devised to minimize total land area occupied by large phased array of antennas and to minimize total length of cables in array. In original intended application, array expanded version of array of paraboloidal-dish microwave communication antennas of Deep Space Network. Layout also advantageous for other phased arrays of antennas and antenna elements, including notably printed-circuit microwave antenna arrays.

  5. Beta decomposition processes in Hf-rich Hf--Nb alloys

    International Nuclear Information System (INIS)

    Jones, W.B.; Taggart, R.; Polonis, D.H.

    1978-01-01

    The decomposition of the bcc β-phase by both athermal and isothermal processes has been investigated in Hf-rich Hf--Nb alloys. An all β-phase structure is retained in chill-cast alloys containing 30 to 50 at.% Nb (Cb), although electron diffraction streaking effects and the behavior of the temperature coefficient of electrical resistivity indicate the presence of a bcc lattice instability similar to that reported in solute lean Ti and Zr alloys. Aging a Hf 0 . 65 Nb 0 . 35 alloy at 400 and 600 0 C resulted in the direct precipitation of a fine dispersion of α-phase needles; this morphology differs from the discs of transition α (α/sub t/) which Carpenter et al observed in Nb-rich Nb 0 . 68 Hf 0 . 32 . During continued aging, the needles grow selectively to form colonies or groups of needles in which both the individual needles and the groups of needles have major axes aligned along (110)/sub β/ type directions. The initial α-phase particles exhibit the Burgers orientation relationship with the parent matrix; continued aging changes the electron diffraction patterns in a way that is similar to that observed in aged Ti--Mo and Ti--Mo--Al alloys where they were attributed to the α-phase having a different crystallographic relationship to the β-phase (Type 2 α-phase). The observed changes in the electron diffraction patterns of aged Hf 0 . 65 Nb 0 . 35 cannot be described as resulting from strained Burgers α-phase

  6. Antenna development for astroparticle and radioastronomy experiments

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-11

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

  7. Millimeter-wave antennas configurations and applications

    CERN Document Server

    du Preez, Jaco

    2016-01-01

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

  8. A Review of Antennas for Picosatellite Applications

    Directory of Open Access Journals (Sweden)

    Abdul Halim Lokman

    2017-01-01

    Full Text Available Cube Satellite (CubeSat technology is an attractive emerging alternative to conventional satellites in radio astronomy, earth observation, weather forecasting, space research, and communications. Its size, however, poses a more challenging restriction on the circuitry and components as they are expected to be closely spaced and very power efficient. One of the main components that will require careful design for CubeSats is their antennas, as they are needed to be lightweight, small in size, and compact or deployable for larger antennas. This paper presents a review of antennas suitable for picosatellite applications. An overview of the applications of picosatellites will first be explained, prior to a discussion on their antenna requirements. Material and antenna topologies which have been used will be subsequently discussed prior to the presentation of several deployable configurations. Finally, a perspective and future research work on CubeSat antennas will be discussed in the conclusion.

  9. Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    J. G. Joshi

    2012-01-01

    Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

  10. Spherical near-field antenna measurements — The most accurate antenna measurement technique

    DEFF Research Database (Denmark)

    Breinbjerg, Olav

    2016-01-01

    The spherical near-field antenna measurement technique combines several advantages and generally constitutes the most accurate technique for experimental characterization of radiation from antennas. This paper/presentation discusses these advantages, briefly reviews the early history and present...

  11. Hf isotope evidence for a hidden mantle reservoir

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2002-01-01

    High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir-marked by an unradiogenic...... Hf isotopic composition and preserved in the deep mantle for at least 3 b.y.-may account for the mass imbalance in Earth's Hf-Nd budget. The Hf isotopic data presented here support a common mantle source region and genetic link between carbonatite and some oceanic-island basalt volcanoes....

  12. Microstructural characterization of as-cast hf-b alloys

    Directory of Open Access Journals (Sweden)

    João Carlos Jânio Gigolotti

    2012-04-01

    Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

  13. PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

    Directory of Open Access Journals (Sweden)

    Dwi Biyantoro

    2017-01-01

    Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

  14. High-temperature x-ray diffraction study of HfTiO4-HfO2 solid solutions

    International Nuclear Information System (INIS)

    Carpenter, D.A.

    1975-01-01

    High-temperature x-ray diffraction techniques were used to determine the axial thermal expansion curves of HfTiO 4 -HfO 2 solid solutions as a function of composition. Data show increasing anisotropy with increasing HfO 2 content. An orthorhombic-to-monoclinic phase transformation was detected near room temperature for compositions near the high HfO 2 end of the orthorhombic phase field and for compositions within the two-phase region (HfTiO 4 solid solution plus HfO 2 solid solution). An orthorhombic-to-cubic phase transformation is indicated by data from oxygen-deficient materials at greater than 1873 0 K. (U.S.)

  15. An Approach for Smart Antenna Testbed

    Science.gov (United States)

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

    2003-07-01

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

  16. VAlidation STandard antennas: Past, present and future

    DEFF Research Database (Denmark)

    Drioli, Luca Salghetti; Ostergaard, A; Paquay, M

    2011-01-01

    designed for validation campaigns of antenna measurement ranges. The driving requirements of VAST antennas are their mechanical stability over a given operational temperature range and with respect to any orientation of the gravity field. The mechanical design shall ensure extremely stable electrical....../V-band of telecom satellites. The paper will address requirements for future VASTs and possible architecture for multi-frequency Validation Standard antennas....

  17. International Mapping of Antenna-Measurement Facilities

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  18. Porous textile antenna designs for improved wearability

    Science.gov (United States)

    Shahariar, Hasan; Soewardiman, Henry; Muchler, Clifford A.; Adams, Jacob J.; Jur, Jesse S.

    2018-04-01

    Textile antennas are an integral part of the next generation personalized wearable electronics system. However, the durability of textile antennas are rarely discussed in the literature. Typical textile antennas are prone to damage during normal wearable user scenarios, washing, and heat cycling over time. Fabricating a durable, washable, flexible, and breathable (like textile materials) antenna is challenging due to the incompatibility of the mechanical properties of conductive materials and soft textile materials. This paper describes a scalable screen printing process on an engineered nonwoven substrate to fabricate microstrip patch antennas with enhanced durability. This work used an Evolon® nonwoven substrate with low surface roughness (˜Ra = 18 μm) and high surface area (˜2.05 mm2 mm-2 of fabric area) compared to traditional textile materials, which allows the ink to penetrate evenly in the fiber bulk with its strong capillary wicking force and enhances print resolution. The composite layer of ink and fiber is conductive and enables the antennas to maintain high mechanical flexibility without varying its RF (Radio Frequency) properties. Additionally, the antennas are packaged by laminating porous polyurethane web to make the device durable and washable. The fully packaged antennas maintain the structural flexibility and RF functionality after 15 cycles of washing and drying. To improve the air permeability and enhance flexibility the antenna is also modified by incorporating holes in the both patch and ground layer of the antenna. The antennas were analyzed before and after submerging in water to observe the effect of wetting and drying with respect to frequency response. The porous antenna with holes recovered 3x times faster than the one without holes (solid) from fully wet state (saturated with water) to the dry state, demonstrating its potential use as a moisture sensor system.

  19. Reconfigurable antennas radiations using plasma Faraday cage

    OpenAIRE

    Barro , Oumar Alassane; Himdi , Mohamed; Lafond , Olivier

    2015-01-01

    International audience; This letter presents a new reconfigurable plasma antenna associated with a Faraday cage. The Faraday cage is realized using a fluorescent lamp. A patch antenna with a broadside radiation pattern or a monopole antenna with an end-fire radiation pattern , operating at 2.45 GHz, is placed inside Faraday cage. The performance of the reconfigurable system is observed in terms of input reflection coefficient, gain and radiation pattern via simulation and measurement. It is s...

  20. Design of reconfigurable antennas using graph models

    CERN Document Server

    Costantine, Joseph; Christodoulou, Christos G; Christodoulou, Christos G

    2013-01-01

    This lecture discusses the use of graph models to represent reconfigurable antennas. The rise of antennas that adapt to their environment and change their operation based on the user's request hasn't been met with clear design guidelines. There is a need to propose some rules for the optimization of any reconfigurable antenna design and performance. Since reconfigurable antennas are seen as a collection of self-organizing parts, graph models can be introduced to relate each possible topology to a corresponding electromagnetic performance in terms of achieving a characteristic frequency of oper

  1. Handbook of smart antennas for RFID systems

    CERN Document Server

    2010-01-01

    The Handbook of Smart Antennas for RFID Systems is a single comprehensive reference on the smart antenna technologies applied to RFID. This book will provide a timely reference book for researchers and students in the areas of both smart antennas and RFID technologies. It is the first book to combine two of the most important wireless technologies together in one book. The handbook will feature chapters by leading experts in both academia and industry offering an in-depth description of terminologies and concepts related to smart antennas in various RFID systems applications.

  2. Thermal Loss in High-Q Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Bahramzy, Pevand; Svendsen, Simon

    2014-01-01

    Tunable antennas are very promising for future generations of mobile communications, where antennas are required to cover a wide range operating bands. This letter aims at characterizing the loss mechanism of tunable antennas. Tunable antennas typically exhibit a high Quality factor (Q), which ca...... lead to thermal loss due to the conductivity of the metal. The investigation shows that copper loss is non-negligible for high Q values. In the proposed design the copper loss is 2 dB, for a Q of 260 at 700 MHz....

  3. MILA Antenna Control Unit Replacement Project

    Science.gov (United States)

    Bresette, Jeremy

    2007-01-01

    The Air to Ground Subsystem (AGS) Antenna Control Units at the MILA Ground Network Tracking Station are at end-of-life and are being replaced. AGS consists of two antennas at MILA (Quad-Helix and Teltrac). Software was taken from the existing Subsystem Controller and modified for the Antenna Control Unit (ACU). The software is capable of receiving and sending commands to and from the ACU. Moving the azimuth clockwise, counterclockwise, moving the elevation up or down, turning servo power on and off, and inputting azimuth and elevation angles are commands that the antenna can receive.

  4. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

    Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.

  5. Vivaldi Antenna for RF Energy Harvesting

    Directory of Open Access Journals (Sweden)

    J. Schneider

    2016-12-01

    Full Text Available Energy harvesting is a future technology for capturing ambient energy from the environment to be recycled to feed low-power devices. A planar antipodal Vivaldi antenna is presented for gathering energy from GSM, WLAN, UMTS and related applications. The designed antenna has the potential to be used in energy harvesting systems. Moreover, the antenna is suitable for UWB applications, because it operates according to FCC regulations (3.1 – 10.6 GHz. The designed antenna is printed on ARLON 600 substrate and operates in frequency band from 0.810 GHz up to more than 12 GHz. Experimental results show good conformity with simulated performance.

  6. Simultaneous analysis of rotational and vibrational-rotational spectra of DF and HF to obtain irreducible molecular constants for HF

    International Nuclear Information System (INIS)

    Horiai, Koui; Uehara, Hiromichi

    2011-01-01

    Graphical abstract: Available rotational and vibrational-rotational spectral lines of DF and HF are analyzed simultaneously using a non-Born-Oppenheimer effective Hamiltonian. Research highlights: → Simultaneous analysis of DF and HF spectral data. → Application of a non-Born-Oppenheimer effective Hamiltonian. → Twenty irreducible molecular constants for HF have been determined. - Abstract: Analytic expressions of corrections for the breakdown of the Born-Oppenheimer approximation to Dunham's Y ij with optimal parameters, i.e., determinable clusters of expansion coefficients, are applied to a data analysis of the rotational and vibrational-rotational transitions of HF reported in the literature. All the available spectral lines of the two isotopologues, DF and HF, are simultaneously fitted to a single set of molecular parameters of HF within experimental errors. Fitting of a data set of 595 spectral transitions for DF and HF has generated only 20 minimal independent parameter values, i.e., 'irreducible' molecular constants of HF, that are sufficient to precisely generate 82 Y ij coefficients and 144 band constants in total: 41 Y ij and 72 band constants each for DF and HF.

  7. A 3D printed helical antenna with integrated lens

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2015-01-01

    A novel antenna configuration comprising a helical antenna with an integrated lens is demonstrated in this work. The antenna is manufactured by a unique combination of 3D printing of plastic material (ABS) and inkjet printing of silver nano

  8. Inkjet-Printed Ultra Wide Band Fractal Antennas

    KAUST Repository

    Maza, Armando Rodriguez

    2012-01-01

    reduction, a Cantor-based fractal antenna which performs a larger bandwidth compared to previously published UWB Cantor fractal monopole antenna, and a 3D loop fractal antenna which attains miniaturization, impedance matching and multiband characteristics

  9. Development of Novel Integrated Antennas for CubeSats

    Data.gov (United States)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-15

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  12. Experimental application of QCD antennas

    International Nuclear Information System (INIS)

    Bobrovskyi, Sergei

    2010-02-01

    A serious problem in searches for new physics at the LHC is the rejection of QCD induced multijet events. In this thesis the formalism of QCD antenna variables based on the SPHEL approximation of QCD matrix elements is applied for the rst time on experimentally reconstructed jets in order to discriminate QCD from supersymmetric processes. The new observables provide additional information with respect to traditional event shape variables. Albeit correlated with experimentally measured missing transverse energy, the variables can be used to improve the signal to background ratio. (orig.)

  13. Experimental application of QCD antennas

    Energy Technology Data Exchange (ETDEWEB)

    Bobrovskyi, Sergei

    2010-02-15

    A serious problem in searches for new physics at the LHC is the rejection of QCD induced multijet events. In this thesis the formalism of QCD antenna variables based on the SPHEL approximation of QCD matrix elements is applied for the rst time on experimentally reconstructed jets in order to discriminate QCD from supersymmetric processes. The new observables provide additional information with respect to traditional event shape variables. Albeit correlated with experimentally measured missing transverse energy, the variables can be used to improve the signal to background ratio. (orig.)

  14. Solar energy collection by antennas

    Energy Technology Data Exchange (ETDEWEB)

    Corkish, R.; Green, M.A.; Puzzer, T. [University of New South Wales, Sydney (Australia). Centre for Advanced Silicon Photovoltaics and Photonics

    2002-12-01

    The idea of collecting solar electromagnetic radiation with antenna-rectifier (rectenna) structures was proposed three decades ago but has not yet been achieved. The idea has been promoted as having potential to achieve efficiency approaching 100% but thermodynamic considerations imply a lower limit of 85.4% for a non-frequency-selective rectenna and 86.8% for one with infinite selectivity, assuming maximal concentration in each case. This paper reviews the history and technical context of solar rectennas and discusses the major issues: thermodynamic efficiency limits, rectifier operation at optical frequencies, harmonics production and electrical noise. (author)

  15. Antenna analysis using neural networks

    Science.gov (United States)

    Smith, William T.

    1992-01-01

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

  16. Direct currents produced by hf heating of plasma

    International Nuclear Information System (INIS)

    Klima, R.

    1974-01-01

    In addition to the well-known diffusion currents, toroidal direct currents arise in h.f. heated plasmas as a result of a momentum transfer from the h.f. field to plasma particles. The estimates of steady-state conditions are given for these currents. Particularly, the possibility of stationary operation of a Tokamak device is analyzed. (author)

  17. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates are simi...

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

    Science.gov (United States)

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

    1992-09-01

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

  19. 47 CFR 74.737 - Antenna location.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna location. 74.737 Section 74.737 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... Booster Stations § 74.737 Antenna location. (a) An applicant for a new low power TV, TV translator, or TV...

  20. 47 CFR 74.1237 - Antenna location.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna location. 74.1237 Section 74.1237 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO... FM Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant for a new station to be...

  1. 3D printed helical antenna with lens

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2016-01-01

    of 3D and 2D inkjet printing of dielectric and metallic inks respectively, we demonstrate a Fresnel lens that has been monolithically integrated to a non-planar antenna (helix) for the first time. Antenna measurements show that the integration of a

  2. 47 CFR 73.753 - Antenna systems.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna systems. 73.753 Section 73.753 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate...

  3. Active patch antennas for transponder applications

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-01-01

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

  4. Multiband Patch Antenna for Femtocell Application

    Directory of Open Access Journals (Sweden)

    M. R. Zaman

    2014-01-01

    Full Text Available A microstrip patch antenna for multiple LTE (long term evaluation frequency bands for femtocell application is proposed in this paper. Distributed antenna solution (DAS has been introduced in cellular network to achieve homogenous indoor coverage. Femtocell is the latest extension to these solutions. It is a smart solution to both coverage and capacity scales. Femtocell operation in LTE band is occupied by higher frequency bands. For multiband femtocell application, miniature antenna design is quite essential. The antenna proposed here is composed of basic monopole structure with two parasitic elements at both sides of the active element. A rectangular slot is introduced at the ground plane of the proposed antenna. The antenna is designed using ElnoS HK light CCL substrate material of relative permittivity of 9.4, dielectric loss-tangent of 0.003 and thickness of 3 mm. The S11 response of the antenna is shown to have a bandwidth of 1.01 GHz starting from 1.79 GHz to 2.8 GHz. The characteristics of the antenna are analysed using Ansoft HFSS software.

  5. Waveguide Phased Array Antenna Analysis and Synthesis

    NARCIS (Netherlands)

    Visser, H.J.; Keizer, W.P.M.N.

    1996-01-01

    Results of two software packages for analysis and synthesis of waveguide phased array antennas are shown. The antennas consist of arrays of open-ended waveguides where irises can be placed in the waveguide apertures and multiple dielectric sheets in front of the apertures in order to accomplish a

  6. Antenna Design Exploiting the Duplex Isolation

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Pedersen, Gert Frølund

    2013-01-01

    A novel design addressing the antenna bandwidth issue for future communication standards on handsets is presented. It consists of a tunableantenna- pair for operation with a tunable front-end. The antennas are narrow-band and frequency-reconfigurable. This Letter focuses on the low communication ...

  7. Wireless SAW Sensors Having Integrated Antennas

    Science.gov (United States)

    Gallagher, Mark (Inventor); Malocha, Donald C. (Inventor)

    2015-01-01

    A wireless surface acoustic wave sensor includes a piezoelectric substrate, a surface acoustic wave device formed on the substrate, and an antenna formed on the substrate. In some embodiments, the antenna is formed on the surface of the substrate using one or more of photolithography, thin film processing, thick film processing, plating, and printing.

  8. First Joint Observations of Radio Aurora by the VHF and HF Radars of the ISTP SB RAS

    Science.gov (United States)

    Berngardt, O. I.; Lebedev, V. P.; Kutelev, K. A.; Kushnarev, D. S.; Grkovich, K. V.

    2018-01-01

    Two modern radars for diagnosis of the ionosphere by the radio-wave backscattering method, namely, the Irkutsk incoherent scatter radar at VHF (IISR, 154-162 MHz) and the Ekaterinburg coherent radar at HF (EKB, 8-20 MHz) are operated at the Institute of Solar-Terrestrial Physics, Siberian Branch of the Russian Academy of Sciences (ISTP SB RAS). The paper analyzes the results of joint observations of strong scattering (radio aurora) on June 8, 2015. To determine the geographical position of the radio aurora, we developed original methods that take into account both the features of the radio-wave propagation and the features of the radar antenna systems. It is shown that there are areas where the spatial position of the HF and VHF radio aurora can coincide. This permits using the radars as a single complex for diagnosis of the characteristics of small-scale high-latitude irregularities in the ionospheric E and F layers. A comparative analysis of the characteristics and temporal dynamics of the radio-aurora region in the HF and VHF ranges is performed. Using the DMSP satellite data, it has been shown that the radio aurora dynamics during this experiment with the EKB radar can be related with the spatial dynamics of the localized area with high electric field, which moves from high to equatorial latitudes. It is found that due to the broader field of view, radio aurora at the HF radar was stably observed 6-12 min earlier than at the VHF radar. This permits using the EKB radar data for prediction of the radio-aurora detection by the IISR radar.

  9. GPS Antenna Data Needed : GPS Adjacent Band Compatibility Workshop Volpe Center, Cambridge MA

    Science.gov (United States)

    2014-09-18

    Topics. 1. Technical Objective: Receiver Antenna Mask and Electronics Data. 2. Definition of Receiver Antenna Mask. 3. Use of Receiver Antenna Mask. 4. Approaches to Generate the Antenna Mask. 5. Request for Receiver Antenna Data. 6. Next Steps.

  10. Reflectarray antennas theory, designs, and applications

    CERN Document Server

    Nayeri, Payam; Elsherbeni, Atef Z

    2018-01-01

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

  11. Super wideband characteristics of monopolar patch antenna

    Directory of Open Access Journals (Sweden)

    Xi Chen

    2013-12-01

    Full Text Available A simple method of acquiring super wideband characteristics for monopolar patch antenna is proposed. Through adopting a modified cone as feeding and radiating structure, the monopolar patch antenna can reach the impedance bandwidth of more than 1:23.4 for voltage standing wave ratio (VSWR ≤ 2. In the whole operating band, the antenna has the like-monopole omnidirectional radiation patterns and the peak gains of 3.8–8.7 dB. Meanwhile, the height of the antenna is just 0.074λ(c, and the diameter of the radiated body is 0.205λ(c, which is smaller than other ultra-wideband omnidirectional antenna.

  12. Textile UWB Antenna Bending and Wet Performances

    Directory of Open Access Journals (Sweden)

    Mai A. R. Osman

    2012-01-01

    Full Text Available The vision and ideas of wearable computing systems describe future electronic systems as an integral part of our everyday clothing that provides the wearer with such intelligent personal assistants. Recently, there has been growing interest in the antenna community to merge between wearable systems technology, ultrawideband (UWB technology and textile technology. This work aimed to make closer steps towards real wearability by investigating the possibilities of designing wearable UWB antenna where textile materials are used for the substrate as well as the conducting parts of the designed antenna. Two types of conducting materials have been used for conducting parts, while a nonconducting fabric has been used as antenna substrate material. A set of comparative results of the proposed design were presented and discussed. Moreover, effects on the return loss by means of measurements for each fabricated antenna prototype under bent and fully wet conditions were discussed in more details.

  13. Present and future JET ICRF antennae

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  14. 5G MIMO Conformal Microstrip Antenna Design

    Directory of Open Access Journals (Sweden)

    Qian Wang

    2017-01-01

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

  15. Antenna complexes protect Photosystem I from Photoinhibition

    Science.gov (United States)

    Alboresi, Alessandro; Ballottari, Matteo; Hienerwadel, Rainer; Giacometti, Giorgio M; Morosinotto, Tomas

    2009-01-01

    Background Photosystems are composed of two moieties, a reaction center and a peripheral antenna system. In photosynthetic eukaryotes the latter system is composed of proteins belonging to Lhc family. An increasing set of evidences demonstrated how these polypeptides play a relevant physiological function in both light harvesting and photoprotection. Despite the sequence similarity between antenna proteins associated with the two Photosystems, present knowledge on their physiological role is mostly limited to complexes associated to Photosystem II. Results In this work we analyzed the physiological role of Photosystem I antenna system in Arabidopsis thaliana both in vivo and in vitro. Plants depleted in individual antenna polypeptides showed a reduced capacity for photoprotection and an increased production of reactive oxygen species upon high light exposure. In vitro experiments on isolated complexes confirmed that depletion of antenna proteins reduced the resistance of isolated Photosystem I particles to high light and that the antenna is effective in photoprotection only upon the interaction with the core complex. Conclusion We show that antenna proteins play a dual role in Arabidopsis thaliana Photosystem I photoprotection: first, a Photosystem I with an intact antenna system is more resistant to high light because of a reduced production of reactive oxygen species and, second, antenna chlorophyll-proteins are the first target of high light damages. When photoprotection mechanisms become insufficient, the antenna chlorophyll proteins act as fuses: LHCI chlorophylls are degraded while the reaction center photochemical activity is maintained. Differences with respect to photoprotection strategy in Photosystem II, where the reaction center is the first target of photoinhibition, are discussed. PMID:19508723

  16. Telecommunications Antennas for the Juno Mission to Jupiter

    Science.gov (United States)

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

    2012-01-01

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

  17. Process Simulation Analysis of HF Stripping

    Directory of Open Access Journals (Sweden)

    Thaer A. Abdulla

    2015-02-01

    Full Text Available    HYSYS process simulator is used for the analysis of existing HF stripping column in LAB plant (Arab Detergent Company, Baiji-Iraq. Simulated column performance and profiles curves are constructed. The variables considered are the thermodynamic model option, bottom temperature, feed temperature, and column profiles for the temperature, vapor flow rate, liquid flow rate and composition. The five thermodynamic models options used (Margules, UNIQUAC, van laar, Antoine, and Zudkevitch-Joffee, affecting the results within (0.1-58% variation for the most cases.        The simulated results show that about 4% of paraffin (C10 & C11 presents at the top stream, which may cause a problem in the LAB production plant. The major variations were noticed for the total top vapor flow rate with bottom temperature and with feed composition. The column profiles maintain fairly constants from tray 5 to tray 18. The study gives evidence about a successful simulation with HYSYS because the results correspond with the real plant operation data.

  18. Grindability of cast Ti-Hf alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

    2006-04-01

    As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

  19. Time variations of hf induced plasma waves

    International Nuclear Information System (INIS)

    Showen, R.L.

    1976-01-01

    Intense plasma waves are generated by an HF pump wave in an ionospheric heating experiment at the Arecibo Observatory. These plasma waves can be observed as enhancements to the ion and plasma lines of the incoherent backscatter echo. The enhancements can be three or four orders of magnitude more intense than the unenhanced lines, and tend to fluctuate wildly. Both the purely growing and the decay mode parametric instabilities are present. When the pump wave is turned on abruptly the enhancements develop in time in a repeatable manner. A rather remarkable feature on time scales of seconds is an overshoot in instability power. These overshoots occur frequently but not universally and last for 1 to 6 seconds. They can have a magnitude from ten to hundreds of times the average instability level. Field aligned irregularities may be the cause of the overshoots. The overshoots appear definitely related to an unusually rapid rise in measured electron temperature that cannot be understood in terms of ohmic energy deposition. On time scales of milliseconds there is a ''mini-overshoot'' before the growth of the instability to a large value. The spectral details also change in a striking manner. The instabilities can first be detected 2 to 4 msec after the pump wave turn-on. The decay mode is present as well as a broad featureless ''noise bump'', which partially sharpens into a line as time progresses. These changes of the spectra in time seem to run counter to the currently accepted theories of plasma wave saturation

  20. Design of silicon-based fractal antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2012-11-20

    This article presents Sierpinski carpet fractal antennas implemented in conventional low resistivity (Ï =10 Ω cm) as well as high resistivity (Ï =1500 Ω cm) silicon mediums. The fractal antenna is 36% smaller as compared with a typical patch antenna at 24 GHz and provides 13% bandwidth on high resistivity silicon, suitable for high data rate applications. For the first time, an on-chip fractal antenna array is demonstrated in this work which provides double the gain of a single fractal element as well as enhanced bandwidth. A custom test fixture is utilized to measure the radiation pattern and gain of these probe-fed antennas. In addition to gain and impedance characterization, measurements have also been made to study intrachip communication through these antennas. The comparison between the low resistivity and high resistivity antennas indicate that the former is not a suitable medium for array implementation and is only suitable for short range communication whereas the latter is appropriate for short and medium range wireless communication. The design is well-suited for compact, high data rate System-on-Chip (SoC) applications as well as for intrachip communication such as wireless global clock distribution in synchronous systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:180-186, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27245 Copyright © 2012 Wiley Periodicals, Inc.

  1. Design of silicon-based fractal antennas

    KAUST Repository

    Ghaffar, Farhan A.; Shamim, Atif

    2012-01-01

    This article presents Sierpinski carpet fractal antennas implemented in conventional low resistivity (Ï =10 Ω cm) as well as high resistivity (Ï =1500 Ω cm) silicon mediums. The fractal antenna is 36% smaller as compared with a typical patch antenna at 24 GHz and provides 13% bandwidth on high resistivity silicon, suitable for high data rate applications. For the first time, an on-chip fractal antenna array is demonstrated in this work which provides double the gain of a single fractal element as well as enhanced bandwidth. A custom test fixture is utilized to measure the radiation pattern and gain of these probe-fed antennas. In addition to gain and impedance characterization, measurements have also been made to study intrachip communication through these antennas. The comparison between the low resistivity and high resistivity antennas indicate that the former is not a suitable medium for array implementation and is only suitable for short range communication whereas the latter is appropriate for short and medium range wireless communication. The design is well-suited for compact, high data rate System-on-Chip (SoC) applications as well as for intrachip communication such as wireless global clock distribution in synchronous systems. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:180-186, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27245 Copyright © 2012 Wiley Periodicals, Inc.

  2. Scalable Notch Antenna System for Multiport Applications

    Directory of Open Access Journals (Sweden)

    Abdurrahim Toktas

    2016-01-01

    Full Text Available A novel and compact scalable antenna system is designed for multiport applications. The basic design is built on a square patch with an electrical size of 0.82λ0×0.82λ0 (at 2.4 GHz on a dielectric substrate. The design consists of four symmetrical and orthogonal triangular notches with circular feeding slots at the corners of the common patch. The 4-port antenna can be simply rearranged to 8-port and 12-port systems. The operating band of the system can be tuned by scaling (S the size of the system while fixing the thickness of the substrate. The antenna system with S: 1/1 in size of 103.5×103.5 mm2 operates at the frequency band of 2.3–3.0 GHz. By scaling the antenna with S: 1/2.3, a system of 45×45 mm2 is achieved, and thus the operating band is tuned to 4.7–6.1 GHz with the same scattering characteristic. A parametric study is also conducted to investigate the effects of changing the notch dimensions. The performance of the antenna is verified in terms of the antenna characteristics as well as diversity and multiplexing parameters. The antenna system can be tuned by scaling so that it is applicable to the multiport WLAN, WIMAX, and LTE devices with port upgradability.

  3. Validating and comparing GNSS antenna calibrations

    Science.gov (United States)

    Kallio, Ulla; Koivula, Hannu; Lahtinen, Sonja; Nikkonen, Ville; Poutanen, Markku

    2018-03-01

    GNSS antennas have no fixed electrical reference point. The variation of the phase centre is modelled and tabulated in antenna calibration tables, which include the offset vector (PCO) and phase centre variation (PCV) for each frequency according to the elevations and azimuths of the incoming signal. Used together, PCV and PCO reduce the phase observations to the antenna reference point. The remaining biases, called the residual offsets, can be revealed by circulating and rotating the antennas on pillars. The residual offsets are estimated as additional parameters when combining the daily GNSS network solutions with full covariance matrix. We present a procedure for validating the antenna calibration tables. The dedicated test field, called Revolver, was constructed at Metsähovi. We used the procedure to validate the calibration tables of 17 antennas. Tables from the IGS and three different calibration institutions were used. The tests show that we were able to separate the residual offsets at the millimetre level. We also investigated the influence of the calibration tables from the different institutions on site coordinates by performing kinematic double-difference baseline processing of the data from one site with different antenna tables. We found small but significant differences between the tables.

  4. Smart antennas for nuclear instruments

    International Nuclear Information System (INIS)

    Jain, Ranjan Bala; Singhi, B.M.

    2005-01-01

    The advances in the field of computer and communications are leading to the development of smart embedded nuclear instruments. These instruments have highly sophisticated signal-processing algorithms based on FPGA and ASICS, provisions of present day connectivity and user interfaces. The developments in the connectivity, standards and bus technologies have made possible to access these instruments on LAN and WAN with suitable reliability and security. To get rid of wires i.e. in order to access these instruments, without wires at any place, wireless technology has evolved and become integral part of day-to-day activities. The environment monitoring can be done remotely, if smart antennas are incorporated on these instruments

  5. Passive Microwave Components and Antennas

    DEFF Research Database (Denmark)

    State-of-the-art microwave systems always require higher performance and lower cost microwave components. Constantly growing demands and performance requirements of industrial and scientific applications often make employing traditionally designed components impractical. For that reason, the design...... and development process remains a great challenge today. This problem motivated intensive research efforts in microwave design and technology, which is responsible for a great number of recently appeared alternative approaches to analysis and design of microwave components and antennas. This book highlights...... techniques. Modelling and computations in electromagnetics is a quite fast-growing research area. The recent interest in this field is caused by the increased demand for designing complex microwave components, modeling electromagnetic materials, and rapid increase in computational power for calculation...

  6. CPW to CPS transition for feeding UWB antennas

    DEFF Research Database (Denmark)

    Butrym, Alexander; Pivnenko, Sergey

    2004-01-01

    The paper considers a transition (balun) from Coplanar Waveguide (CPW) to Coplanar Stripline (CPS) which is non-resonant and suitable for feeding UWB antennas such as Tapered Slot Antennas (Vivaldi antennas in particular), bow-tie antennas, and other. Some numerical and experimental results...

  7. CPW to CPS transition for feeding UWB antennas

    DEFF Research Database (Denmark)

    Butrym, Alexander; Pivnenko, Sergey

    2006-01-01

    The paper considers a transition (balun) from Coplanar Waveguide (CPW) to Coplanar Stripline (CPS) which is non-resonant and suitable for feeding UWB antennas such as Tapered Slot Antennas (Vivaldi antennas, in particular), bow-tie antennas, and other. Some numerical and experimental results...

  8. Logo Antenna for 5.8 GHz Wireless Communications (invited)

    DEFF Research Database (Denmark)

    Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

    2016-01-01

    A logo antenna for the 5.8 GHz ISM band is presented. The idea behind the logo antenna is to use the company or university logo as part of the antenna. When disguised as a logo, it may be more acceptable to place the antenna at optimal locations to obtain good coverage. In the present work...

  9. Logo Antenna for 5.8 GHz Wireless Communications

    DEFF Research Database (Denmark)

    Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

    2016-01-01

    A logo antenna for the 5.8 GHz ISM band is presented. The idea behind the logo antenna is to use the company or university logo as part of the antenna. When disguised as a logo, it may be more acceptable to place the antenna at optimal locations to obtain good coverage. In the present work...

  10. Aerogel-Based Antennas for Aerospace and Terrestrial Applications

    Science.gov (United States)

    Meador, Mary Ann (Inventor); Miranda, Felix (Inventor); Van Keuls, Frederick (Inventor)

    2016-01-01

    Systems and methods for lightweight, customizable antenna with improved performance and mechanical properties are disclosed. In some aspects, aerogels can be used, for example, as a substrate for antenna fabrication. The reduced weight and expense, as well as the increased ability to adapt antenna designs, permits a systems to mitigate a variety of burdens associated with antennas while providing added benefits.

  11. 47 CFR 73.54 - Antenna resistance and reactance measurements.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Antenna resistance and reactance measurements... measurements. (a) The resistance of an omnidirectional series fed antenna is measured at either the base of the... the point of common radiofrequency input to the directional antenna system after the antenna has been...

  12. Slot Antenna for Wireless Temperature Measurement Systems

    DEFF Research Database (Denmark)

    Acar, Öncel; Jakobsen, Kaj Bjarne

    2016-01-01

    This paper presents a novel clover-slot antenna for a surface-acoustic-wave sensor based wireless temperature measurement system. The slot is described by a parametric locus curve that has the shape of a clover. The antenna is operated at high temperatures, in rough environments, and has a 43......% fractional bandwidth at the 2.4 GHz ISM-band. The slot antenna has been optimized for excitation by a passive chip soldered onto it. Measurement results are compared with simulation results and show good agreements....

  13. Rectifying antenna and method of manufacture

    Science.gov (United States)

    Bhansali, Shekhar (Inventor); Buckle, Kenneth (Inventor); Goswami, D. Yogi (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor)

    2006-01-01

    In accordance with the present invention, an aperture rectenna is provided where the substrate is transparent and of sufficient mechanical strength to support the fabricated structure above it. An aperture antenna is deposited on the transparent substrate and a metal-insulator-metal (MIM) diode is constructed on top of the aperture antenna. There is an insulating layer between the aperture antenna metal and the metal ground plane optimized to maximize the collection of incident radiation. The top of the structure is capped with a metal ground plane layer, which also serves as the DC connection points for each rectenna element.

  14. FDTD simulation tools for UWB antenna analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2005-02-01

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

  15. FDTD simulation tools for UWB antenna analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2004-12-01

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

  16. Vertically Polarized Omnidirectional Printed Slot Loop Antenna

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

    2015-01-01

    A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...... pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due to the polarization....

  17. Resonant double loop antenna development at ORNL

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  18. MIMO Communication Using Single Feed Antenna Arrays

    DEFF Research Database (Denmark)

    Alrabadi, Osama

    Multi-input-multi-output (MIMO) communication has emerged as a promis- ing technology for meeting the increasing demand on higher data rates. The technology exploits the spatial resource dimension by sending the datas- treams to different locations in the multi element array (MEA) domain while...... conventionally to a single antenna element while mod- ulating the other datastreams in the analogue RF domain, using simple switched antenna systems (SAS) or sophisticated reactance-assisted antenna systems. The use of a SAS is found simple to implement, but can hardly handle high order signal formats...

  19. Implanted Antennas in Medical Wireless Communications

    CERN Document Server

    Rahmat-Samii, Yahya; Balanis, Constantine

    2006-01-01

    Implanted Antennas in Medical Wireless Communications summarizes the results of recent research activities on the subject of implanted antennas for medical wireless communication systems. It is anticipated that in the near future sophisticated medical devices will be implanted inside the human body for medical telemetry and telemedicine. To establish effective and efficient wireless links with these devices, it is pivotal to give special attention to antenna designs that are low profile, small, safe, and cost effective. In this book, authors Yahya Rahmat-Samii and Jaehoon Kim demonstrate how a

  20. Analysis of the Metal Oxide Space Clouds (MOSC) HF Propagation Environment

    Science.gov (United States)

    Jackson-Booth, N.; Selzer, L.

    2015-12-01

    Artificial Ionospheric Modification (AIM) attempts to modify the ionosphere in order to alter the high frequency (HF) propagation environment. It can be achieved through injections of aerosols, chemicals or radio (RF) signals into the ionosphere. The Metal Oxide Space Clouds (MOSC) experiment was undertaken in April/May 2013 to investigate chemical AIM. Two sounding rockets were launched from the Kwajalein Atoll (part of the Marshall Islands) and each released a cloud of vaporized samarium (Sm). The samarium created a localized plasma cloud, with increased electron density, which formed an additional ionospheric layer. The ionospheric effects were measured by a wide range of ground based instrumentation which included a network of high frequency (HF) sounders. Chirp transmissions were made from three atolls and received at five sites within the Marshall Islands. One of the receive sites consisted of an 18 antenna phased array, which was used for direction finding. The ionograms have shown that as well as generating a new layer the clouds created anomalous RF propagation paths, which interact with both the cloud and the F-layer, resulting in 'ghost traces'. To fully understand the propagation environment a 3D numerical ray trace has been undertaken, using a variety of background ionospheric and cloud models, to find the paths through the electron density grid for a given fan of elevation and azimuth firing angles. Synthetic ionograms were then produced using the ratio of ray path length to speed of light as an estimation of the delay between transmission and observation for a given frequency of radio wave. This paper reports on the latest analysis of the MOSC propagation environment, comparing theory with observations, to further understanding of AIM.

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

    Science.gov (United States)

    Belotserkovskii, G. B.

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

  2. A Fast Adaptive Receive Antenna Selection Method in MIMO System

    Directory of Open Access Journals (Sweden)

    Chaowei Wang

    2013-01-01

    Full Text Available Antenna selection has been regarded as an effective method to acquire the diversity benefits of multiple antennas while potentially reduce hardware costs. This paper focuses on receive antenna selection. According to the proportion between the numbers of total receive antennas and selected antennas and the influence of each antenna on system capacity, we propose a fast adaptive antenna selection algorithm for wireless multiple-input multiple-output (MIMO systems. Mathematical analysis and numerical results show that our algorithm significantly reduces the computational complexity and memory requirement and achieves considerable system capacity gain compared with the optimal selection technique in the same time.

  3. Compact antennas for wireless communications and terminals theory and design

    CERN Document Server

    Laheurte, Jean-Marc

    2012-01-01

    Compact Antennas for Wireless Communications and Terminals deals with compact microwave antennas and, more specifically, with the planar version of these antennas. Planar antennas are the most appropriate type of antenna in modern communication systems and more generally in all applications requiring miniaturization, integration and conformation such as in mobile phone handsets.The book is suitable for students, engineers and scientists eager to understand the principles of planar and small antennas, their design and fabrication issues, and modern aspects such as UWB antennas, recon

  4. Low-Q Electrically Small Spherical Magnetic Dipole Antennas

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2010-01-01

    Three novel electrically small antenna configurations radiating a TE10 spherical mode corresponding to a magnetic dipole are presented and investigated: multiarm spherical helix (MSH) antenna, spherical split ring resonator (S-SRR) antenna, and spherical split ring (SSR) antenna. All three antennas...... are self-resonant, with the input resistance tuned to 50 ohms by an excitation curved dipole/monopole. A prototype of the SSR antenna has been fabricated and measured, yielding results that are consistent with the numerical simulations. Radiation quality factors (Q) of these electrically small antennas (in...

  5. Wireless communication capability of a reconfigurable plasma antenna

    International Nuclear Information System (INIS)

    Kumar, Rajneesh; Bora, Dhiraj

    2011-01-01

    A 30 cm long plasma column is excited by a surface wave, which acts as a plasma antenna. Using plasma properties (pattern formation/striations in plasmas) single plasma antenna can be transformed into array, helical, and spiral plasma antenna. Experiments are carried out to study the power patterns, directivity, and half power beam width of such different plasma antennas. Moreover, field properties of plasma and copper antenna are studied. Further, wireless communication and jamming capability of plasma antenna are tested. Findings of this study suggest that directivity and communication range can be increased by converting single plasma antenna in to array/helical/spiral plasma antenna. Field frequencies of plasma antenna determine the communication and jamming of radio frequency waves. Therefore, this study invokes applications of pattern formation or striations of plasmas in plasma antenna technology.

  6. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    OpenAIRE

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV ...

  7. Low-Frequency Waves in HF Heating of the Ionosphere

    Science.gov (United States)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  8. Theoretical Assessment of 178m2Hf De-Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hartouni, E P; Chen, M; Descalle, M A; Escher, J E; Loshak, A; Navratil, P; Ormand, W E; Pruet, J; Thompson, I J; Wang, T F

    2008-10-06

    This document contains a comprehensive literature review in support of the theoretical assessment of the {sup 178m2}Hf de-excitation, as well as a rigorous description of controlled energy release from an isomeric nuclear state.

  9. HF Surface Wave Radar Operation in Adverse Conditions

    National Research Council Canada - National Science Library

    Ponsford, Anthony M; Dizaji, Reza M; McKerracher, Richard

    2005-01-01

    ...) system based on HF Surface Wave Radar (HFSWR). the primary objective behind the programme was to demonstrate the capability of HFSWR to continuously detect and track surface targets (ships and icebergs...

  10. HF band filter bank multi-carrier spread spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Laraway, Stephen Andrew; Moradi, Hussein; Farhang-Boroujeny, Behrouz

    2015-10-01

    Abstract—This paper describes modifications to the filter bank multicarrier spread spectrum (FB-MC-SS) system, that was presented in [1] and [2], to enable transmission of this waveform in the HF skywave channel. FB-MC-SS is well suited for the HF channel because it performs well in channels with frequency selective fading and interference. This paper describes new algorithms for packet detection, timing recovery and equalization that are suitable for the HF channel. Also, an algorithm for optimizing the peak to average power ratio (PAPR) of the FBMC- SS waveform is presented. Application of this algorithm results in a waveform with low PAPR. Simulation results using a wide band HF channel model demonstrate the robustness of this system over a wide range of delay and Doppler spreads.

  11. HF-voltage testing of accelerating system functional model

    International Nuclear Information System (INIS)

    Gladkov, A.V.; Stepanov, V.B.

    1989-01-01

    Owing to ambiguity in interpreting the notion of the electron strength of the operating HF device in an acceleator a technique of measurements and result processing, based on statistical analysis of the data is suggested. Experimental testing on electric strength of structures with HF focusing was carried out using a bench in the form of a cylindrical vacuum container inside which a double H-resonator with HF quadrupole electrodes without surface modulation was installed. The dependences obtained permit to evaluate the bahaviour of the HF device from the viewpoint of electric strength and radiation hazard for the whole range of possible values of voltage on the basis of data on the frequency of breakdowns and radiation situation only in one experimental point. 12 refs.; 8 figs

  12. Fluorescence Enhancement Factors on Optical Antennas: Enlarging the Experimental Values without Changing the Antenna Design

    Directory of Open Access Journals (Sweden)

    Jérôme Wenger

    2012-01-01

    Full Text Available Plasmonic antennas offer promising opportunities to control the emission of quantum objects. As a consequence, the fluorescence enhancement factor is widely used as a figure of merit for a practical antenna realization. However, the fluorescence enhancement factor is not an intrinsic property of the antenna. It critically depends on several parameters, some of which are often disregarded. In this contribution, I explore the influence of the setup collection efficiency, emitter's quantum yield, and excitation intensity. Improperly setting these parameters may significantly alter the enhancement values, leading to potential misinterpretations. The discussion is illustrated by an antenna example of a nanoaperture surrounded by plasmonic corrugations.

  13. Planar Millimeter-Wave Antennas: A Comparative Study

    Directory of Open Access Journals (Sweden)

    K. Pitra

    2011-04-01

    Full Text Available The paper describes the design and the experimental verification of three types of wideband antennas. Attention is turned to the bow-tie antenna, the Vivaldi antenna and the spiral antenna designed for the operation at millimeter waves. Bandwidth, input impedance, gain, and directivity pattern are the investigated parameters. Antennas are compared considering computer simulations in CST Microwave Studio and measured data.

  14. Integrated magnetics design for HF-link power converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the two integrated magnetic components on the same core do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs. (au)

  15. Large Magnetic Anisotropy in HfMnP

    Science.gov (United States)

    Parker, David; Lamichhane, Tej; Taufour, Valentin; Masters, Morgan; Thimmaiah, Srinivasa; Bud'Ko, Ser'gey; Canfield, Paul

    We present a theoretical and experimental study of two little-studied manganese phosphide ferromagnets, HfMnP and ZrMnP, with Curie temperatures above room temperature. We find an anisotropy field in HfMnP approaching 10 T - larger than that of the permanent magnet workhorse NdFeB magnets. From theory we determine the source of this anisotropy. Our results show the potential of 3d-element-based magnetic materials for magnetic applications.

  16. Stockbridge Antenna Measurement and Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Stockbridge Antenna Measurement Facility is located 23 miles southwest of AFRL¹s Rome Research Site. This unique measurement facility is designed to evaluate the...

  17. Antenna Miniaturization in Complex Electromagnetic Environments

    DEFF Research Database (Denmark)

    Zhang, Jiaying

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

  18. Visualization of electromagnetic exposure near LTE antennae

    Science.gov (United States)

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

    2018-01-01

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

  19. Phase shifter for antenna beam steering

    Energy Technology Data Exchange (ETDEWEB)

    Jindal, Ravi, E-mail: rjindal21@gmail.com [Master’s(MS) in System Electronics and General Electrical, Ecole Polytechnique of university of Nantes France, IETR, Nantes (France); Razban, Tchanguiz, E-mail: tchanguiz.razban-haghighi@univ-nantes.fr [Electronics and Telecommunication Institute of Rennes (IETR-UMR 6164), Ecole Polytechnique of university of Nantes France, IETR, Nantes (France)

    2016-03-09

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  20. GBO RF Anechoic Chamber & Antenna Test Range

    Data.gov (United States)

    Federal Laboratory Consortium — A shielded anechoic chamber measuring 15 by 15 by 37 feet is located in the Jansky Laboratory at Green Bank. This chamber has been outfitted as a far-field antenna...

  1. Phase shifter for antenna beam steering

    International Nuclear Information System (INIS)

    Jindal, Ravi; Razban, Tchanguiz

    2016-01-01

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  2. A Modal Description of Multiport Antennas

    Directory of Open Access Journals (Sweden)

    Jonathan J. Lynch

    2011-01-01

    Full Text Available This paper presents a modal description of multiport antennas that leads directly to a rigorous network representation and simple quadratic expressions for gain, efficiency, and effective area. The analysis shows that the transmitting and receiving properties of an element antenna array are exactly described by a 2×2 element scattering matrix together with a set of orthonormal mode functions and accounts for effects such as mutual coupling, scattering, reflection, and losses. The approach is quite general, only requiring that the antenna be finite and reciprocal. The scattering network description simplifies accounting of power flow while retaining a close connection to the physical antenna characteristics. The orthonormal mode functions provide a complete basis for radiated and received fields, facilitating beamforming. The theory provides rigorous definitions of input-output signals and links them to the underlying electromagnetics in a straightforward manner.

  3. Multiband Photonic Phased-Array Antenna

    Science.gov (United States)

    Tang, Suning

    2015-01-01

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

  4. Development of ceramic-free antenna feeder

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  5. PBG based terahertz antenna for aerospace applications

    CERN Document Server

    Choudhury, Balamati; Jha, Rakesh Mohan

    2016-01-01

    This book focuses on high-gain antennas in the terahertz spectrum and their optimization. The terahertz spectrum is an unallocated EM spectrum, which is being explored for a number of applications, especially to meet increasing demands of high data rates for wireless space communications. Space communication systems using the terahertz spectrum can resolve the problems of limited bandwidth of present wireless communications without radio-frequency interference. This book describes design of such high-gain antennas and their performance enhancement using photonic band gap (PBG) substrates. Further, optimization of antenna models using evolutionary algorithm based computational engine has been included. The optimized high-performance compact antenna may be used for various wireless applications, such as inter-orbital communications and on-vehicle satellite communications.

  6. 3D printed helical antenna with lens

    KAUST Repository

    Farooqui, Muhammad Fahad

    2016-12-19

    The gain of an antenna can be enhanced through the integration of a lens, however this technique has traditionally been restricted to planar antennas due to fabrication limitations of standard manufacturing processes. Here, with a unique combination of 3D and 2D inkjet printing of dielectric and metallic inks respectively, we demonstrate a Fresnel lens that has been monolithically integrated to a non-planar antenna (helix) for the first time. Antenna measurements show that the integration of a Fresnel lens enhances the gain of a 2-turn helix by around 4.6 dB giving a peak gain of about 12.9 dBi at 8.8 GHz.

  7. Hybrid Methods in Designing Sierpinski Gasket Antennas

    Directory of Open Access Journals (Sweden)

    Mudrik Alaydrus

    2010-12-01

    Full Text Available Sierpinki gasket antennas as example of fractal antennas show multiband characteristics. The computer simulation of Sierpinksi gasket monopole with finite ground needs prohibitively large computer memory and more computational time. Hybrid methods consist of surface integral equation method and physical optics or uniform geometrical theory of diffraction should alleviate this computational burdens. The so-called full hybridization of the different methods with modifying the incoming electromagnetic waves in case of hybrid method surface integral equation method and physical optics and modification of the Greens function for hybrid method surface integral equation method and uniform geometrical theory of diffraction plays the central role in the observation. Comparison between results of different methods are given and also measurements of three Sierpinksi gasket antennas. The multiband characteristics of the antennas still can be seen with some reduction and enhancement of resonances.

  8. Resonant-bar gravitational radiation antennas

    International Nuclear Information System (INIS)

    Blair, D.G.

    1987-01-01

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

  9. Focused Application Software for Ferrite Patch Antennas

    National Research Council Canada - National Science Library

    Trott, Keith

    1999-01-01

    ... (brick and tetrahedral elements) are combined by MRC via a graphical user interface (GUI) into a user friendly code capable of modeling conformal antennas with ferrite sub and superstrates recessed in planar surfaces.

  10. Radiation Pattern of Chair Armed Microstrip Antenna

    Science.gov (United States)

    Mishra, Rabindra Kishore; Sahu, Kumar Satyabrat

    2016-12-01

    This work analyzes planar antenna conformable to chair arm shaped surfaces for WLAN application. Closed form expressions for its radiation pattern are developed and validated using measurements on prototype and commercial EM code at 2.4 GHz.

  11. Compact, Frequency Reconfigurable, Printed Monopole Antenna

    Directory of Open Access Journals (Sweden)

    Ricardo Gonçalves

    2012-01-01

    Full Text Available This paper proposes a possible implementation of a compact printed monopole antenna, useful to operate in UMTS and WLAN bands. In order to accomplish that, a miniaturization technique based on the application of chip inductors is used in conjunction with frequency reconfiguration capability. The chip inductors change the impedance response of the monopole, allowing to reduce the resonant frequency. In order to be able to operate the antenna in these two different frequencies, an antenna reconfiguration technique based on PIN diodes is applied. This procedure allows the change of the active form of the antenna leading to a shift in the resonant frequency. The prototype measurements show good agreement with the simulation results.

  12. Resonance spectra of diabolo optical antenna arrays

    Directory of Open Access Journals (Sweden)

    Hong Guo

    2015-10-01

    Full Text Available A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

  13. Heating profiles on ICRF antenna Faraday shields

    International Nuclear Information System (INIS)

    Taylor, D.J.; Baity, F.W.; Hahs, C.L.; Riemer, B.W.; Ryan, P.M.; Williamson, D.E.

    1991-01-01

    A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. A high-heat-flux, uncooled Faraday shield has also been designed for the fast-wave current drive (FWCD) antenna on D3-D. For both components, the improved understanding of the heating profiles made it possible to design for heat fluxes that would otherwise have been too close to mechanically established limits. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the D3-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed. 3 refs., 6 figs., 2 tabs

  14. Thermoelectric properties of doped BaHfO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Dr. Shakuntala Misra National Rehabilitation University, Lucknow-229001, U.P India (India); Bhamu, K. C. [Department of Physics, Goa University, Goa-403 206 (India); Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Feroze Gandhi Institute of Engineering & Technology, Raebareli-229001, U.P India (India)

    2016-05-06

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  15. The isobutylene-isobutane alkylation process in liquid HF revisited.

    Science.gov (United States)

    Esteves, P M; Araújo, C L; Horta, B A C; Alvarez, L J; Zicovich-Wilson, C M; Ramírez-Solís, A

    2005-07-07

    Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and stirring rates are the most important parameters to achieve maximum yield of alkylate, in agreement with experimental findings. The ab initio Car-Parrinello molecular dynamics calculations show that isobutylene is irreversibly protonated in the liquid HF medium at higher densities, leading to the ion pair formation, which is shown to be a minimum on the potential energy surface after optimization using periodic boundary conditions. The HF medium solvates preferentially the fluoride anion, which is found as solvated [FHF](-) or solvated F(-.)(HF)(3). On the other hand, the tert-butyl cation is weakly solvated, where the closest HF molecules appear at a distance of about 2.9 Angstrom with the fluorine termination of an HF chain.

  16. Solid phase crystallisation of HfO2 thin films

    International Nuclear Information System (INIS)

    Modreanu, M.; Sancho-Parramon, J.; O'Connell, D.; Justice, J.; Durand, O.; Servet, B.

    2005-01-01

    In this paper, we report on the solid phase crystallisation of carbon-free HfO 2 thin films deposited by plasma ion assisted deposition (PIAD). After deposition, the HfO 2 films were annealed in N 2 ambient for 3 h at 350, 550 and 750 deg. C. Several characterisation techniques including X-ray reflectometry (XRR), X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and atomic force microscopy (AFM) were used for the physical characterisation of as-deposited and annealed HfO 2 . XRD has revealed that the as-deposited HfO 2 film is in an amorphous-like state with only traces of crystalline phase and that the annealed films are in a highly crystalline state. These results are in good agreement with the SE results showing an increase of refractive index by increasing the annealing temperature. XRR results show a significant density gradient over the as-deposited film thickness, which is characteristic of the PIAD method. The AFM measurements show that the HfO 2 layers have a smooth surface even after annealing at 750 deg. C. The present study demonstrates that the solid phase crystallisation of HfO 2 PIAD thin films starts at a temperature as low as 550 deg. C

  17. Sequential sputtered Co-HfO{sub 2} granular films

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M.; Ng, V.

    2017-03-15

    A systematic study of magnetic, magneto-transport and micro-structural properties of Co-HfO{sub 2} granular films fabricated by sequential sputtering is presented. We demonstrate reduction in ferromagnetic-oxide formation by using HfO{sub 2} as the insulting matrix. Microstructure evaluation of the films showed that the film structure consisted of discrete hcp-Co grains embedded in HfO{sub 2} matrix. Films with varying compositions were prepared and their macroscopic properties were studied. We correlate the variation in these properties to the variation in film microstructure. Our study shows that Co-HfO{sub 2} films with reduced cobalt oxide and varying properties can be prepared using sequential sputtering technique. - Highlights: • Co-HfO{sub 2} granular films were prepared using sequential sputtering. • A reduction in ferromagnetic-oxide formation is observed. • Co-HfO{sub 2} films display superparamagnetism and tunnelling magneto-resistance. • Varying macroscopic properties were achieved by changing film composition. • Applications can be found in moderate MR sensors and high –frequency RF devices.

  18. Deep Space Network Antenna Logic Controller

    Science.gov (United States)

    Ahlstrom, Harlow; Morgan, Scott; Hames, Peter; Strain, Martha; Owen, Christopher; Shimizu, Kenneth; Wilson, Karen; Shaller, David; Doktomomtaz, Said; Leung, Patrick

    2007-01-01

    The Antenna Logic Controller (ALC) software controls and monitors the motion control equipment of the 4,000-metric-ton structure of the Deep Space Network 70-meter antenna. This program coordinates the control of 42 hydraulic pumps, while monitoring several interlocks for personnel and equipment safety. Remote operation of the ALC runs via the Antenna Monitor & Control (AMC) computer, which orchestrates the tracking functions of the entire antenna. This software provides a graphical user interface for local control, monitoring, and identification of faults as well as, at a high level, providing for the digital control of the axis brakes so that the servo of the AMC may control the motion of the antenna. Specific functions of the ALC also include routines for startup in cold weather, controlled shutdown for both normal and fault situations, and pump switching on failure. The increased monitoring, the ability to trend key performance characteristics, the improved fault detection and recovery, the centralization of all control at a single panel, and the simplification of the user interface have all reduced the required workforce to run 70-meter antennas. The ALC also increases the antenna availability by reducing the time required to start up the antenna, to diagnose faults, and by providing additional insight into the performance of key parameters that aid in preventive maintenance to avoid key element failure. The ALC User Display (AUD) is a graphical user interface with hierarchical display structure, which provides high-level status information to the operation of the ALC, as well as detailed information for virtually all aspects of the ALC via drill-down displays. The operational status of an item, be it a function or assembly, is shown in the higher-level display. By pressing the item on the display screen, a new screen opens to show more detail of the function/assembly. Navigation tools and the map button allow immediate access to all screens.

  19. Designing a fractal antenna of 2400 MHz

    International Nuclear Information System (INIS)

    Miranda Hamburger, Fabio

    2012-01-01

    The design of a fractal antenna with 2400 MHz of frequency has been studied. The fractal used is described by Waclaw Spierpi.ski. The initial figure, also known as seed, is divided using equilateral triangles with the aim of obtaining a perimeter similar to a meaningful portion of wave length. The use of λ to establish an ideal perimeter has reduced the radiation resistance. The adequate number of iterations needed to design the antenna is calculated based on λ. (author) [es

  20. 3D Printing Electrically Small Spherical Antennas

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2013-01-01

    3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations.......3D printing is applied for rapid prototyping of an electrically small spherical wire antenna. The model is first printed in plastic and subsequently covered with several layers of conductive paint. Measured results are in good agreement with simulations....

  1. Time-Zone-Pattern Satellite Broadcasting Antenna

    Science.gov (United States)

    Galindo, Victor; Rahmat-Samii, Yahya; Imbriale, William A.; Cohen, Herb; Cagnon, Ronald R.

    1988-01-01

    Direct-broadcast satellite antenna designs provide contoured beams to match four time zones in 48 contiguous states and spot beams for Alaska, Hawaii, and Puerto Rico presented in 29-page report. Includes descriptions of procedures used to arrive at optimized designs. Arrangements, amplitudes, and phases of antenna feeds presented in tables. Gain contours shown graphically. Additional tables of performance data given for cities in service area of Eastern satellite.

  2. A note on antennas: Definitions and methods

    DEFF Research Database (Denmark)

    Bach, Henning

    1987-01-01

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

  3. International Conference on Antenna Theory and Techniques

    Science.gov (United States)

    1999-12-03

    Krüger, Introduction to Solar radio astronomy and radio physics.- D.Reidel publishing company. Dordrecht: Hol- land/Boston: USA. London: England. 1982...REFERENCES 1. M. S. Juk, J. B. Molochkov Designing lens, scan- ning, broadband of antennae and feeder devices. - Moscow: Energia , 1973. - 440 p...system of this antenna was exe- cuted. Besides the thermal deformations of a mirror caused by daytime solar heating were investigated as well as

  4. Magneto-Electric Dipole Antenna Arrays

    OpenAIRE

    Gupta, Shulabh; Jiang, Li Jun; Caloz, Christophe

    2014-01-01

    A planar magneto-electric (ME) dipole antenna array is proposed and demonstrated by both full-wave analysis and experiments. The proposed structure leverages the infinite wavelength propagation characteristic of composite right/left-handed (CRLH) transmission lines to form high-gain magnetic radiators combined with radial conventional electric radiators, where the overall structure is excited by a single differential feed. The traveling-wave type nature of the proposed ME-dipole antenna enabl...

  5. Helicon plasma with additional immersed antenna

    International Nuclear Information System (INIS)

    Aanesland, A; Charles, C; Boswell, R W; Fredriksen, A

    2004-01-01

    A 'primary' RF power (H-power) at 13.56 MHz is coupled to a plasma source excited by an external double saddle field Helicon antenna. A 'secondary' RF power (S-power), also at 13.56 MHz but with variable phase, is additionally coupled by inserting a second antenna in contact with the plasma through one end of the source. The immersed antenna can be grounded or floating, allowing a self-bias to form in the latter case. Changes in the plasma density and electron temperature are measured in both cases with varying power on the immersed antenna. The plasma potential increases dramatically with S-power in the grounded case, and is found to be similar in size to the sum of the plasma potential and the self-bias formed in the floating case for all powers. Hence, the sheath between the immersed antenna and the plasma is shown to be equal in both the grounded and floating cases. Although the power efficiency does not vary significantly as a function of the S-power, it is consistently lower for the grounded case possibly as a result of a dc current to ground. The plasma parameters are drastically changed as the phase between the two antennae are varied (floating case), and a sinusoidal function was fitted to the plasma parameters as a function of the phase shift. The calculated power loss to the antenna indicates that the power efficiency of the immersed antenna, as the phase is changed, is altered from 80% to 10%

  6. Surface circulation patterns at the southeastern Bay of Biscay: new observations from HF radar data

    Science.gov (United States)

    Solabarrieta, L.; Rubio, A.; Medina, R.; Paduan, J. D.; Castanedo, S.; Fontán, A.; Cook, M.; González, M.

    2012-12-01

    A CODAR Seasonde High Frequency (HF) radar network has been operational since the beginning of 2009 for the oceanic region of the Basque Country, Spain (south-eastern Bay of Biscay, Atlantic Ocean). It forms part of the Basque operational data acquisition system, established by the Directorate of Emergency Attention and Meteorology of the Basque Government. It is made up of two antennas, at the capes Higer (43d 23.554' N, 1d 47.745' W) and Matxitxako (43d 7.350' N, 2d 45.163' W), emitting at 4.525 MHz frequency and 30 kHz bandwidth. This system provides hourly surface currents with 5.12 km spatial resolution, covering 10,000 km2. Space- and time-covering measurements have been available in the study area since 2009. The data contribute considerably to the study of surface current patterns and the main physical processes in the area. Additional applications relate to security of navigation, maritime rescue, validation and improvement of numerical models, etc. For comparison with other validation studies and to obtain an estimate of the performance of the Basque system, statistical and spectral analysis of the surface currents obtained through the HF radar and different in-situ platforms have been conducted. The analyses show values of comparison between the different measuring systems consistent with those done by other authors (Paduan and Rosenfeld, 1996; Kaplan et al., 2005). The radar is able to reproduce the time evolution of the currents with a reasonable accuracy; likewise, the main three spectral peaks (inertial, semidiurnal and diurnal) are well resolved. In this context, the aim of this work is to show the HF radar ability to measure accurately the surface currents in the south-eastern Bay of Biscay and to study the ocean circulation in the area (figures 1 and 2). Surface current patterns are analysed and described for the period 2009-2011, for different timescales. A clear seasonality at a large-scale has been observed in accordance with previous work

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

    Science.gov (United States)

    Manning, Robert M.

    2007-01-01

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

  8. Printing of Wearable Antenna on Textile

    Directory of Open Access Journals (Sweden)

    Khirotdin Rd. Khairilhijra

    2018-01-01

    Full Text Available A wearable antenna which is meant to be a part of the clothing used for communication purposes includes tracking, navigation and mobile computing has been seen in demand due to the recent miniaturization of wireless devices. Printing of conductive ink provides flexibility properties on electronics thus allowing it to be used on conformal surfaces. However, the current printing techniques mostly suffer from ink incompatibility and limited of substrates to be printed with. Hence, this paper intend to discloses the printing of wearable antenna using alternative technique via syringe-based deposition system with conductive ink on textile. A validation between simulation and measurement of return loss, (S11 and radiation pattern of the antenna printed is also performed. It was found that a functional antenna is successfully printed on textile since the performances obtained are as expected. The antenna resonated at a minimum resonant frequency of 1.82 GHz which the S11 gathered at-18.90 dB. The radiation pattern for both simulation and measurement is as predicted since both have a larger magnitude of the main lobe than the side lobe. The magnitude of the main lobe from measurement was observed to be 8.83 dB higher than the magnitude of the main lobe of the simulation which is only 3.77 dB. It is proven that the syringe-based deposition system is capable of printing functional antenna on textile.

  9. Compact super-wideband optical antenna

    Science.gov (United States)

    Wang, Wen C.; Forber, Richard; Bui, Kenneth

    2009-05-01

    We present progress on advanced optical antennas, which are compact, small size-weight-power units capable to receive super wideband radiated RF signals from 30 MHz to over 3 GHz. Based on electro-optical modulation of fiber-coupled guided wave light, these dielectric E-field sensors exhibit dipole-like azimuthal omni directionality, and combine small size (channels, and high EO sensing materials. The antenna system photonic link consists of a 1550 nm PM fiber-pigtailed laser, a specialized optical modulator antenna in channel waveguide format, a wideband photoreceiver, and optical phase stabilizing components. The optical modulator antenna design employs a dielectric (no electrode) Mach-Zehnder interferometer (MZI) arranged so that sensing RF bandwidth is not limited by optical transit time effects, and MZI phase drift is bias stabilized. For a prototype optical antenna system that is < 100 in3, < 10 W, < 5 lbs, we present test data on sensitivity (< 20 mV/m-Hz1/2), RF bandwidth, and antenna directionality, and show good agreement with theoretical predictions.

  10. Antenna development for astroparticle and radioastronomy experiments

    International Nuclear Information System (INIS)

    Charrier, Didier

    2012-01-01

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

  11. Three-dimensional analysis of antenna sheaths

    International Nuclear Information System (INIS)

    Myra, J.R.; D'Ippolito, D.A.; Ho, Y.L.

    1996-01-01

    The present work is motivated by the importance of r.f. sheaths in determining the antenna-plasma interaction and the sensitivity of the sheaths to the complicated three-dimensional structure of modern ion cyclotron range of frequency (ICRF) antennas. To analyze r.f. sheaths on the plasma facing regions of the launcher, we first calculate the contact points of the tokamak magnetic field lines on the surface of the antenna Faraday screen and nearby limiters for realistic three-dimensional magnetic flux surface and antenna geometries. Next, the r.f. voltage that can drive sheaths at the contact points is determined and used to assess the resulting sheath power dissipation, r.f.-driven sputtering, and r.f.-induced convective cells (which produce edge profile modification). The calculations are embodied in a computer code, ANSAT (antenna sheath analysis tool), and sample ANSAT runs are shown to highlight the physics- and geometry-dependent characteristics of the r.f. sheaths and their relationship to the antenna design. One use of ANSAT is therefore as a design tool, to assess the strengths and weaknesses of a given design with respect to critical voltage handling and edge plasma interaction issues. Additionally, examples are presented where ANSAT has been useful in the analysis and interpretation of ICRF experiments (orig.)

  12. Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

    Science.gov (United States)

    Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

    2017-09-01

    The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

  13. Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

    Science.gov (United States)

    Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

    2006-01-01

    Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

  14. Isothermal cross-sections of Hf-Sc-Ga(800 deg C) and Hf-Ti-Ga (750 deg C) phase diagrams

    International Nuclear Information System (INIS)

    Markiv, V.Ya.; Belyavina, N.N.

    1981-01-01

    Isothermal cross sections of Hf-Sc-Ga (800 deg C) and Hf-Ti-Ga (750 deg C) state diagrams are plotted. The existence of two ternary Hfsub(0.1-0.8)Scsub(0.9)-sub(0.2)Ga and Hfsub(0.8)Scsub(0.2)Gasub(3) phases is stated in the Hf-Sc-Ga system. The crystal structure of these compounds investigated by the powder method belongs to the structural α-MoB and ZrAl 3 types respectively. Continuous rows of (Hf, Sc 5 Ga 5 , (Hf, Ti)Ga 3 and (Hf, Ti)Ga 2 solid solutions are formed in the investigated systems. Essential quantity of the third component dissolve binary Sc 5 Ga 4 , Sc 2 Ga 3 (15 and 30 at % Hf respectively), Hf 5 Ga 4 , HfGa 2 (20, 10 at. % Sc), Hf 5 Ga 4 , HfGa, Hf 5 Ga 3 , Hf 2 Ga 3 (48, 30, 46, 20 at. % Ti) gallides [ru

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

    Science.gov (United States)

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

    2018-06-01

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

  16. Ge interactions on HfO2 surfaces and kinetically driven patterning of Ge nanocrystals on HfO2

    International Nuclear Information System (INIS)

    Stanley, Scott K.; Joshi, Sachin V.; Banerjee, Sanjay K.; Ekerdt, John G.

    2006-01-01

    Germanium interactions are studied on HfO 2 surfaces, which are prepared through physical vapor deposition (PVD) and by atomic layer deposition. X-ray photoelectron spectroscopy and temperature-programed desorption are used to follow the reactions of germanium on HfO 2 . Germanium chemical vapor deposition at 870 K on HfO 2 produces a GeO x adhesion layer, followed by growth of semiconducting Ge 0 . PVD of 0.7 ML Ge (accomplished by thermally cracking GeH 4 over a hot filament) also produces an initial GeO x layer, which is stable up to 800 K. PVD above 2.0 ML deposits semiconducting Ge 0 . Temperature programed desorption experiments of ∼1.0 ML Ge from HfO 2 at 400-1100 K show GeH 4 desorption below 600 K and GeO desorption above 850 K. These results are compared to Ge on SiO 2 where GeO desorption is seen at 550 K. Exploiting the different reactivity of Ge on HfO 2 and SiO 2 allows a kinetically driven patterning scheme for high-density Ge nanoparticle growth on HfO 2 surfaces that is demonstrated

  17. Theoretical predictions of hydrolysis and complex formation of group-4 elements Zr, Hf and Rf in HF and HCl solutions

    International Nuclear Information System (INIS)

    Pershina, V.; Trubert, D.; Le Naour, C.; Kratz, J.V.

    2002-01-01

    Fully relativistic molecular density-functional calculations of the electronic structures of hydrated, hydrolyzed and fluoride/chloride complexes have been performed for group-4 elements Zr, Hf, and element 104, Rf. Using the electronic density distribution data, relative values of the free energy change for hydrolysis and complex formation reactions were defined. The results show the following trend for the first hydrolysis step of the cationic species: Zr>Hf>Rf in agreement with experiments. For the complex formation in HF solutions, the trend to a decrease from Zr to Hf is continued with Rf, provided no hydrolysis takes place. At pH>0, further fluorination of hydrolyzed species or fluoro-complexes has an inversed trend in the group Rf≥Zr>Hf, with the difference between the elements being very small. For the complex formation in HCl solutions, the trend is continued with Rf, so that Zr>Hf>Rf independently of pH. A decisive energetic factor in hydrolysis or complex formation processes proved to be a predominant electrostatic metal-ligand interaction. Trends in the K d (distribution coefficient) values for the group-4 elements are expected to follow those of the complex formation

  18. Relationship between CCR and NT-proBNP in Chinese HF patients, and their correlations with severity of HF.

    Science.gov (United States)

    Lu, Zhigang; Wang, Bo; Wang, Yunliang; Qian, Xueqing; Zheng, Wei; Wei, Meng

    2014-01-01

    To evaluate the relationship between creatinine clearance rate (CCR) and the level of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in heart failure (HF) patients and their correlations with HF severity. Two hundred and one Chinese patients were grouped according to the New York Heart Association (NYHA) classification as NYHA 1-2 and 3-4 groups and 135 cases out of heart failure patients as control group. The following variables were compared among these three groups: age, sex, body mass index (BMI), smoking status, hypertension, diabetes, NT-proBNP, creatinine (Cr), uric acid (UA), left ventricular end-diastolic diameter (LVEDD), and CCR. The biomarkers of NT-proBNP, Cr, UA, LVEDD, and CCR varied significantly in the three groups, and these variables were positively correlated with the NHYA classification. The levels of NT-proBNP and CCR were closely related to the occurrence of HF and were independent risk factors for HF. At the same time, there was a significant negative correlation between the levels of NT-proBNP and CCR. The area under the receiver operating characteristic curve suggested that the NT-proBNP and CCR have high accuracy for diagnosis of HF and have clinical diagnostic value. NT-proBNP and CCR may be important biomarkers in evaluating the severity of HF.

  19. Joint Efforts Towards European HF Radar Integration

    Science.gov (United States)

    Rubio, A.; Mader, J.; Griffa, A.; Mantovani, C.; Corgnati, L.; Novellino, A.; Schulz-Stellenfleth, J.; Quentin, C.; Wyatt, L.; Ruiz, M. I.; Lorente, P.; Hartnett, M.; Gorringe, P.

    2016-12-01

    During the past two years, significant steps have been made in Europe for achieving the needed accessibility to High Frequency Radar (HFR) data for a pan-European use. Since 2015, EuroGOOS Ocean Observing Task Teams (TT), such as HFR TT, are operational networks of observing platforms. The main goal is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of HFR data access and tools. Particular attention is being paid by HFR TT to converge from different projects and programs toward those common objectives. First, JERICO-NEXT (Joint European Research Infrastructure network for Coastal Observatory - Novel European eXpertise for coastal observaTories, H2020 2015 Programme) will contribute on describing the status of the European network, on seeking harmonization through exchange of best practices and standardization, on developing and giving access to quality control procedures and new products, and finally on demonstrating the use of such technology in the general scientific strategy focused by the Coastal Observatory. Then, EMODnet (European Marine Observation and Data Network) Physics started to assemble HF radar metadata and data products within Europe in a uniform way. This long term program is providing a combined array of services and functionalities to users for obtaining free of charge data, meta-data and data products on the physical conditions of European sea basins and oceans. Additionally, the Copernicus Marine Environment Monitoring Service (CMEMS) delivers from 2015 a core information service to any user related to 4 areas of benefits: Maritime Safety, Coastal and Marine Environment, Marine Resources, and Weather, Seasonal Forecasting and Climate activities. INCREASE (Innovation and Networking for the integration of Coastal Radars into EuropeAn marine SErvices - CMEMS Service Evolution 2016) will set the necessary developments towards the integration of existing European

  20. Performance Enhancement of the Patch Antennas Applying Micromachining Technology

    Directory of Open Access Journals (Sweden)

    Mohamed N. Azermanesh

    2007-09-01

    Full Text Available This paper reports on the application of micromachining technology for performance enhancement of two types of compact antennas which are becoming a common practice in microsystems. Shorted patch antennas (SPA and folded shorted patch antennas operating in the 5-6 GHz ISM band, with intended application in short-range wireless communications, are considered. The electrical length of antennas are modified by etching the substrate of the antennas, thus providing a new degree of freedom to control the antenna operating properties, which is the main novelty of our work. The gain and bandwidth of the antennas are increased by increasing the etching depth. However, etching the substrate affects the operating frequency as well. To keep the operating frequency at a pre-specified value, the dimension of the antennas must be increased by deepening the etching depth. Therefore, a trade off between the performance enhancement of the antennas and the dimensional enlargement is required.

  1. Analysis of equivalent antenna based on FDTD method

    Directory of Open Access Journals (Sweden)

    Yun-xing Yang

    2014-09-01

    Full Text Available An equivalent microstrip antenna used in radio proximity fuse is presented. The design of this antenna is based on multilayer multi-permittivity dielectric substrate which is analyzed by finite difference time domain (FDTD method. Equivalent iterative formula is modified in the condition of cylindrical coordinate system. The mixed substrate which contains two kinds of media (one of them is airtakes the place of original single substrate. The results of equivalent antenna simulation show that the resonant frequency of equivalent antenna is similar to that of the original antenna. The validity of analysis can be validated by means of antenna resonant frequency formula. Two antennas have same radiation pattern and similar gain. This method can be used to reduce the weight of antenna, which is significant to the design of missile-borne antenna.

  2. Characteristics of the wire biconical antenna used for EMC measurements

    Science.gov (United States)

    Austin, Brian A.; Fourie, Andre P. C.

    1991-08-01

    The characteristics of a wire biconical antenna that determine its antenna factor were computed by using the method of moments code NEC-2. A fairly extensive validation exercise was conducted from which a suitable computer model was derived. The input impedance, gain, and radiation patterns of the antenna were computed for special cases where the biconical antenna is used above a conducting ground plane for open-field EMC (electromagnetic compatibility) testing. The effects of height above the ground plane and polarization of the antenna on these parameters were found and the antenna factor was corrected for them. The current distribution along the antenna elements was also examined, and it was found that significant pattern distortion can occur at some frequencies when a horizontal wire biconical antenna is used close to the ground. These results will allow this broadband antenna to be used with confidence in applications where previously only resonant dipoles were specified.

  3. Performance Verification on UWB Antennas for Breast Cancer Detection

    Directory of Open Access Journals (Sweden)

    Vijayasarveswari V.

    2017-01-01

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

  4. Superconducting microstrip antennas: An experimental comparison of two feeding methods

    International Nuclear Information System (INIS)

    Richard, M.A.; Claspy, P.C.; Bhasin, K.B.

    1993-01-01

    The recent discovery of high-temperature superconductors (HTS's) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. In this paper, two methods for feeding HTS microstrip antennas at K and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gap-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals

  5. 60 GHz Antenna Diagnostics from Planar Near Field Antenna Measurement Without External Frequency Conversion

    DEFF Research Database (Denmark)

    Popa, Paula Irina; Pivnenko, Sergey; Breinbjerg, Olav

    2015-01-01

    ,J.M. Nielsen, O. Breinbjerg, 60 GHz Antenna Measurement Setup using a VNA without External Frequency Conversion,36th Annual Symposium of the Antenna Measurement Technique Association ,October 12-17,Tucson, Arizona, 2014]. In this work we extend the validation of this 60 GHz planar near-field (PNF) set...

  6. Vertically Polarized Omnidirectional Printed Slot Loop AntennaPrinted Slot Loop Antenna (invited)

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren Helstrup; Thaysen, Jesper

    2015-01-01

    and in-phase fields in the slot in order to obtain an omnidirectional radiation pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due...

  7. Pulsed energy storage antennas for ionospheric modification

    Directory of Open Access Journals (Sweden)

    R. F. Wuerker

    2005-01-01

    Full Text Available Interesting, "new", very high peak-power pulsed radio frequency (RF antennas have been assembled at the HIPAS Observatory (Alaska, USA and also at the University of California at Los Angeles (UCLA, USA; namely, a pair of quarter wavelength (λ/4 long cylindrical conductors separated by a high voltage spark gap. Such a combination can radiate multi-megawatt RF pulses whenever the spark gap fires. The antenna at HIPAS is 53m long (λ/2 with a central pressurized SF6 spark gap. It is mounted 5 meters (λ/21 above a ground plane. It radiates at 2.85MHz. The two antenna halves are charged to ± high voltages by a Tesla coil. Spark gap voltages of 0.4 MV (at the instant of spark gap closure give peak RF currents of ~1200A which correspond to ~14 MW peak total radiated power, or ~56 MW of Effective Radiated Power (ERP. The RF pulse train is initially square, decaying exponentially in time with Qs of ~50. Two similar but smaller 80-MHz antennas were assembled at UCLA to demonstrate their synchronization with a pulsed laser which fired the spark gaps in the two antennas simultanoeously. These experiments show that one can anticipate a pulsed array of laser synchronized antennas having a coherent Effective Radiated Power (ERP>10GW. One can even reconsider a pulse array radiating at 1.43MHz which corresponds to the electron gyrofrequency in the Earth's magnetic field at ~200km altitude. These "new" pulsed high power antennas are hauntingly similar to the ones used originally by Hertz (1857-1894 during his (1886-1889 seminal verifications of Maxwell's (1864 theory of electrodynamics.

  8. Pulsed energy storage antennas for ionospheric modification

    Directory of Open Access Journals (Sweden)

    R. F. Wuerker

    2005-01-01

    Full Text Available Interesting, "new", very high peak-power pulsed radio frequency (RF antennas have been assembled at the HIPAS Observatory (Alaska, USA and also at the University of California at Los Angeles (UCLA, USA; namely, a pair of quarter wavelength (λ/4 long cylindrical conductors separated by a high voltage spark gap. Such a combination can radiate multi-megawatt RF pulses whenever the spark gap fires. The antenna at HIPAS is 53m long (λ/2 with a central pressurized SF6 spark gap. It is mounted 5 meters (λ/21 above a ground plane. It radiates at 2.85MHz. The two antenna halves are charged to ± high voltages by a Tesla coil. Spark gap voltages of 0.4 MV (at the instant of spark gap closure give peak RF currents of ~1200A which correspond to ~14 MW peak total radiated power, or ~56 MW of Effective Radiated Power (ERP. The RF pulse train is initially square, decaying exponentially in time with Qs of ~50. Two similar but smaller 80-MHz antennas were assembled at UCLA to demonstrate their synchronization with a pulsed laser which fired the spark gaps in the two antennas simultanoeously. These experiments show that one can anticipate a pulsed array of laser synchronized antennas having a coherent Effective Radiated Power (ERP>10GW. One can even reconsider a pulse array radiating at 1.43MHz which corresponds to the electron gyrofrequency in the Earth's magnetic field at ~200km altitude. These "new" pulsed high power antennas are hauntingly similar to the ones used originally by Hertz (1857-1894 during his (1886-1889 seminal verifications of Maxwell's (1864 theory of electrodynamics.

  9. Dielectric optical antenna thermal emitters and metamaterials

    Science.gov (United States)

    Schuller, Jonathan Aaron

    Optical antennas are critical components in nanophotonics research due to their unparalleled ability to concentrate electromagnetic energy into nanoscale volumes. Researchers typically construct such antennas from wavelength-size metallic structures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize all-dielectric optical antennas, emitters, and metamaterials. In this thesis, we experimentally and theoretically characterize the resonant modes of subwavelength rod-shaped dielectric particles and demonstrate their use in negative index metamaterials and novel infrared light emitters. At mid-infrared frequencies, Silicon Carbide (SiC) is an ideal system for studying the behavior of dielectric optical antennas. At frequencies below the TO phonon resonance, SiC behaves like a dielectric with very large refractive index. Using infrared spectroscopy and analytical Mie calculations we show that individual rod-shaped SiC particles exhibit a multitude of resonant modes. Detailed investigations of these SiC optical antennas reveal a wealth of new physics and applications. We discuss the distinct electromagnetic field profile for each mode, and demonstrate that two of the dielectric-type Mie resonances can be combined in a particle array to form a negative index metamaterial. We further show that these particles can serve as "broadcasting" antennas. Using a custom-built thermal emission microscope we collect emissivity spectra from single SiC particles at elevated temperatures, highlighting their use as subwavelength resonant light emitters. Finally, we derive and verify a variety of general analytical results applicable to all cylindrical dielectric antennas.

  10. Dielectric Optical Antenna Emitters and Metamaterials

    Science.gov (United States)

    Schuller, Jon

    2009-03-01

    Optical antennas are critical components in nanophotonics research due to their unparalleled ability to concentrate electromagnetic energy into nanoscale volumes. Researchers typically construct such antennas from wavelength-size metallic structures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize all-dielectric optical antennas, emitters, and metamaterials. In this talk, we experimentally and theoretically characterize the resonant modes of subwavelength rod-shaped dielectric particles and demonstrate their use in negative index metamaterials and novel infrared light emitters. At mid-infrared frequencies, Silicon Carbide (SiC) is an ideal system for studying the behavior of dielectric optical antennas. At frequencies below the TO phonon resonance, SiC behaves like a dielectric with very large refractive index. Using infrared spectroscopy and analytical Mie calculations we show that individual rod-shaped SiC particles exhibit a multitude of resonant modes. Detailed investigations of these SiC optical antennas reveal a wealth of new physics and applications. We discuss the distinct electromagnetic field profile for each mode, and demonstrate that two of the dielectric-type Mie resonances can be combined in a particle array to form a negative index metamaterial [1]. We further show that these particles can serve as ``broadcasting'' antennas. Using a custom-built thermal emission microscope we collect emissivity spectra from single SiC particles at elevated temperatures, highlighting their use as subwavelength resonant light emitters. Finally, we derive and verify a variety of general analytical results applicable to all cylindrical dielectric antennas and discuss extensions of the demonstrated concepts to different materials systems and frequency regimes. [1] J.A. Schuller, et al., Phys. Rev. Lett. 99, 107401 (2007)

  11. Coulomb-nuclear interference measurements of 168Yb, 176Hf, 178Hf, and 180Hf and lifetime measurements in 186Hg

    International Nuclear Information System (INIS)

    Nettles, W.G.

    1979-01-01

    Alpha scattering measurements were performed at center-of-mass energies near the Coulomb barrier. These energies allow for nuclear as well as pure Coulomb forces to play a significant role in the excitation process. The interference of these two forces is very sensitive to the sign of the E4 ground-state moment, whereas pure Coulomb excitation is not. Systematics of the E4 moments of the rare earth mass region indicate a transition in the magnitude and sign of the reduced matrix element of the M(E4) operator between 0 + and 4 + states from small and positive to large and negative between Yb and W. Previous Coulomb-nuclear interference measurements show that this reduced matrix element for 180 Hf is large and negative. The present results agree with that conclusion. It is also shown that the above reduced matrix element for 178 Hf, like that of 180 Hf, is large and negative. The small and positive moment (matrix element) for 168 Yb is seen to be consistent with the experimental data. No conclusions are drawn for the E4 moment in 176 Hf. The measurement of nuclear lifetimes shorter than 500 ps requires the use of plastic scintilltor detectors. These detectors, however have very poor energy resolution. A system is described that uses plastic scintillators with a magnetic lens spectrometer for energy selection. The system was used to measure the lifetime of the 522-keV 0 + sate in 186 Hf. A data analysis method using higher-order distribution moments is also presented

  12. [Effect of a multifunctional instrument (HF scissors) in parotis surgery].

    Science.gov (United States)

    Strauss, G; Schaller, S; Gollnick, I

    2014-03-01

    Lateral parotidectomy is a demanding surgical procedure and requires a large number of instruments with a high frequency (HF) of alternating. Many functions, such as preparing, spreading, coagulating and cutting could be combined by using scissors with an integrated function of bipolar coagulation. This study has targeted an investigation of technical application, influence on surgery time, frequency of HF application and change of instruments. In the period between 01 April 2011 and 30 September 2012 (18 months) 35 procedures of lateral parotidectomy in 35 patients were investigated. In all cases lateral parotidectomy was carried out with a similar technique (modified extracapsular preparation). Workflow data were used from a control group in the period between 01 January 2009 and 31 December 2010 (24 months). The following parameters from both groups were documented and evaluated: incision-suture times (subdivided into nine sections of the procedure), change of instruments, period of application for HF function and early facial nerve function (6 h and 6 days after surgery according to House-Brackmann). Additionally, in the HF+ group a questionnaire that facilitated subjective evaluation of instruments was analyzed. It was possible to perform the surgery in both groups with neither technical nor surgical intraoperative complications. Incision-suture times showed an average reduction of 31.6 min (34.8 %) in the HF+ group. There was a reduction in the change of instruments compared to a conventional group (CONV) by up to 62.7 %. With the deployment of HF scissors there was a clear increase in the use of HF surgery by more than 100 % when comparing incision-suture times. Evaluation of both groups according to House-Brackmann showed a similar postoperative facial nerve function. The surgeons involved were of the opinion that in all 35 surgeries with HF scissors the intervention was easier and more comfortable. The use of HF scissors is appropriate for parotid gland

  13. U Patch Antenna for RFID and Wireless Applications

    International Nuclear Information System (INIS)

    Abi Saad, R.; Melhem, Z.; Nader, C.; Zaatar, Y.; Zaouk, D.

    2011-01-01

    in this paper, we propose a new multi-band patch antenna structure for embedded RFID (Radio Frequency Identification) readers and wireless communications. The proposed antenna is a dual band microstrip patch antenna using U-slot geometry. The operating frequencies of the proposed antenna are chosen as 2.4 and 0.9 (GHz), obtained by optimizing the physical dimensions of the U-slot. Several parameters have been investigated using Ansoft Designer software. The antenna is fed through a quarter wavelength transformer for impedance matching. An additional layer of alumina is added above the surface of the conductors to increase the performance of the antenna. (author)

  14. Curtain Antenna Array Simulation Research Based on MATLAB

    Directory of Open Access Journals (Sweden)

    Hongbo LIU

    2014-01-01

    Full Text Available For the radiating capacity of curtain antenna array, this paper constructs a three- line-four-column curtain antenna array using cage antenna as the antenna array element and obtains a normalizing 3D radiation patterns through conducting simulation with MATLAB. Meanwhile, the relationships between the antenna spacing and the largest directivity coefficient, as well as the communication frequency and largest directivity coefficient are analyzed in this paper. It turns out that the max value will generate when the antenna spacing is around 18 m and the best communication effect will be achieved when the communication frequency is about 12.4 MHz.

  15. A Modal Approach to Compact MIMO Antenna Design

    Science.gov (United States)

    Yang, Binbin

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

  16. Numerical Simulation of Plasma Antenna with FDTD Method

    International Nuclear Information System (INIS)

    Chao, Liang; Yue-Min, Xu; Zhi-Jiang, Wang

    2008-01-01

    We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconBgurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design

  17. Numerical simulation of plasma antenna with FDTD method

    International Nuclear Information System (INIS)

    Liang Chao; Xu Yuemin; Wang Zhijiang

    2008-01-01

    We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconfigurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design. (authors)

  18. Inkjet-Printed Ultra Wide Band Fractal Antennas

    KAUST Repository

    Maza, Armando Rodriguez

    2012-05-01

    In this work, Paper-based inkjet-printed Ultra-wide band (UWB) fractal antennas are presented. Three new designs, a combined UWB fractal monopole based on the fourth order Koch Snowflake fractal which utilizes a Sierpinski Gasket fractal for ink reduction, a Cantor-based fractal antenna which performs a larger bandwidth compared to previously published UWB Cantor fractal monopole antenna, and a 3D loop fractal antenna which attains miniaturization, impedance matching and multiband characteristics. It is shown that fractals prove to be a successful method of reducing fabrication cost in inkjet printed antennas while retaining or enhancing printed antenna performance.

  19. Draft revision of human factors guideline HF-010

    International Nuclear Information System (INIS)

    Lee, Hyun Chul; Lee, Yong Hee; Oh, In Seok; Lee, Jung Woon; Cha, Woo Chang; Lee, Dhong Ha

    2003-05-01

    The Application of Human Factors to the design of Man-Machine Interfaces System(MMIS) in the nuclear power plant is essential to the safety and productivity of the nuclear power plants, human factors standards and guidelines as well as human factors analysis methods and experiments are weightily used to the design application. A Korean engineering company has developed a human factors engineering guideline, so-call HF-010, and has used it for human factors design, however the revision of HF-010 is necessary owing to lack of the contents related to the advanced MMI(Man-Machine Interfaces). As the results of the reviews of HF-010, it is found out that the revision of Section 9. Computer Displays of HF-010 is urgent, thus the revision was drafted on the basis of integrated human factors design guidelines for VDT, human factors design guidelines for PMAS SPADES display, human factors design guidelines for PMAS alarm display, and human factors design guidelines for electronic displays developed by the surveillance and operation support project of KOICS. The draft revision of HF-010 Section 9 proposed in this report can be utilized for the human factors design of the advanced MMI, and the high practical usability of the draft can be kept up through the continuous revision according to the advancement of digital technology

  20. High efficiency carbon nanotube thread antennas

    Science.gov (United States)

    Amram Bengio, E.; Senic, Damir; Taylor, Lauren W.; Tsentalovich, Dmitri E.; Chen, Peiyu; Holloway, Christopher L.; Babakhani, Aydin; Long, Christian J.; Novotny, David R.; Booth, James C.; Orloff, Nathan D.; Pasquali, Matteo

    2017-10-01

    Although previous research has explored the underlying theory of high-frequency behavior of carbon nanotubes (CNTs) and CNT bundles for antennas, there is a gap in the literature for direct experimental measurements of radiation efficiency. These measurements are crucial for any practical application of CNT materials in wireless communication. In this letter, we report a measurement technique to accurately characterize the radiation efficiency of λ/4 monopole antennas made from the CNT thread. We measure the highest absolute values of radiation efficiency for CNT antennas of any type, matching that of copper wire. To capture the weight savings, we propose a specific radiation efficiency metric and show that these CNT antennas exceed copper's performance by over an order of magnitude at 1 GHz and 2.4 GHz. We also report direct experimental observation that, contrary to metals, the radiation efficiency of the CNT thread improves significantly at higher frequencies. These results pave the way for practical applications of CNT thread antennas, particularly in the aerospace and wearable electronics industries where weight saving is a priority.

  1. An Design of HF-Band RFID System with Multiple Readers and Passive Tags for Indoor Mobile Robot Self-Localization

    Directory of Open Access Journals (Sweden)

    Jian Mi

    2016-07-01

    Full Text Available Radio frequency identification (RFID technology has already been explored for efficient self-localization of indoor mobile robots. A mobile robot equipped with RFID readers detects passive RFID tags installed on the floor in order to locate itself. The Monte-Carlo localization (MCL method enables the localization of a mobile robot equipped with an RFID system with reasonable accuracy, sufficient robustness and low computational cost. The arrangements of RFID readers and tags and the size of antennas are important design parameters for realizing accurate and robust self-localization using a low-cost RFID system. The design of a likelihood model of RFID tag detection is also crucial for the accurate self-localization. This paper presents a novel design and arrangement of RFID readers and tags for indoor mobile robot self-localization. First, by considering small-sized and large-sized antennas of an RFID reader, we show how the design of the likelihood model affects the accuracy of self-localization. We also design a novel likelihood model by taking into consideration the characteristics of the communication range of an RFID system with a large antenna. Second, we propose a novel arrangement of RFID tags with eight RFID readers, which results in the RFID system configuration requiring much fewer readers and tags while retaining reasonable accuracy of self-localization. We verify the performances of MCL-based self-localization realized using the high-frequency (HF-band RFID system with eight RFID readers and a lower density of RFID tags installed on the floor based on MCL in simulated and real environments. The results of simulations and real environment experiments demonstrate that our proposed low-cost HF-band RFID system realizes accurate and robust self-localization of an indoor mobile robot.

  2. Centrifugal stretching along the ground state band of 168Hf

    International Nuclear Information System (INIS)

    Costin, A.; Pietralla, N.; Reese, M.; Moeller, O.; Ai, H.; Casten, R. F.; Heinz, A.; McCutchan, E. A.; Meyer, D. A.; Qian, J.; Werner, V.; Dusling, K.; Fitzpatrick, C. R.; Guerdal, G.; Petkov, P.; Rainovski, G.

    2009-01-01

    The lifetimes of the J π =4 + , 6 + , 8 + , and 10 + levels along the ground state band in 168 Hf were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in 168 Hf were populated using the 124 Sn( 48 Ti,4n) fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus 168 Hf. The data agree with the predictions from the geometrical confined β-soft (CBS) rotor model that involves centrifugal stretching in a soft potential

  3. Determining characteristics of HF communications links using SuperDARN

    Directory of Open Access Journals (Sweden)

    J. M. Hughes

    2002-07-01

    Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

  4. Determining characteristics of HF communications links using SuperDARN

    Directory of Open Access Journals (Sweden)

    J. M. Hughes

    Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.

    Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

  5. Densification and properties of HfB2 based materials

    International Nuclear Information System (INIS)

    Sonber, J.K.; Ch Murthy, T.S.R.; Bedse, R.D.; Subramanian, C.; Kumar, Sunil; Fotedar, R.K.; Krishnamurthy, N.; Suri, A.K.

    2011-01-01

    This paper presents the results of investigation carried out on densification and properties of HfB 2 based materials. Densification study of HfB 2 with and without sinter additive was carried out by hot pressing. TiSi 2 and CrSi 2 were used as sinter additive. Monolithic HfB 2 was densified to only 80%ρ th at 1850 deg C with a pressure of 35 MPa. Addition of 10 wt% TiSi 2 resulted in a density of 95% TD at a relatively low temperature of 1650 deg C and a low pressure of 20 MPa. Addition of 10% CrSi 2 resulted in a density of 99% TD at the same operating conditions. All the samples were characterized by SEM/EDS and mechanical property measurement. (author)

  6. HF-START: A Regional Radio Propagation Simulator

    Science.gov (United States)

    Hozumi, K.; Maruyama, T.; Saito, S.; Nakata, H.; Rougerie, S.; Yokoyama, T.; Jin, H.; Tsugawa, T.; Ishii, M.

    2017-12-01

    HF-START (HF Simulator Targeting for All-users' Regional Telecommunications) is a user-friendly simulator developed to meet the needs of space weather users. Prediction of communications failure due to space weather disturbances is of high priority. Space weather users from various backgrounds with high economic impact, i.e. airlines, telecommunication companies, GPS-related companies, insurance companies, international amateur radio union, etc., recently increase. Space weather information provided by Space Weather Information Center of NICT is, however, too professional to be understood and effectively used by the users. To overcome this issue, I try to translate the research level data to the user level data based on users' needs and provide an immediate usable data. HF-START is positioned to be a space weather product out of laboratory based truly on users' needs. It is originally for radio waves in HF band (3-30 MHz) but higher frequencies up to L band are planned to be covered. Regional ionospheric data in Japan and southeast Asia are employed as a reflector of skywave mode propagation. GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy) model will be used as ionospheric input for global simulation. To evaluate HF-START, an evaluation campaign for Japan region will be launched in coming months. If the campaign successes, it will be expanded to southeast Asia region as well. The final goal of HF-START is to provide the near-realtime necessary radio parameters as well as the warning message of radio communications failure to the radio and space weather users.

  7. A Novel Compact Dual-Polarized Antenna

    Directory of Open Access Journals (Sweden)

    Yong Cheng

    2016-01-01

    Full Text Available A novel compact dual-polarized antenna is proposed. The antenna has a 1.43% impedance bandwidth which is from 1801 MHz to 1827 MHz for return loss larger than 10 dB. The isolation between the two ports is above 28 dB in the bandwidth, and the gain is 6.6 dBi. The proposed antenna not only consists of a full-planar structure, but also is easy to be fabricated for its simple structure. Additionally, a section of slots and slits is cut on the radiation patch to reduce the area of it to 54% compared with the conventional square patch.

  8. Recent developments in ICRF antenna modelling

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  9. Sensitivity of a combined gravitational antenna

    International Nuclear Information System (INIS)

    Kulagin, V.V.; Rudenko, V.N.

    1986-01-01

    A modification of a combined optico-acoustic gravitational antenna: a long-base laser interferometer, where free masses are changed by Weber resonators, is suggested. The combined gravitational antenna can possess sensitivity h min ∼ 10 -18 without deep cooling of Weber resonators and h min ∼ 10 -19 at helium temperaure of the resonators. This antenna has the following new quantities: presence of three independent responses, that permits to a considerable extent to exclude non-gravitational effects; presence of responses of two separated Weber resonators, that permits to register the wave character of gravitational perturbation by measuring phase shift between relaxation ''tails''. It means that one may with certainty register the wave structure of gravitational radiation for perturbation of metrics h, exceeding the threshold sensitivity of the known detectors by an order

  10. Statistical monitoring of linear antenna arrays

    KAUST Repository

    Harrou, Fouzi

    2016-11-03

    The paper concerns the problem of monitoring linear antenna arrays using the generalized likelihood ratio (GLR) test. When an abnormal event (fault) affects an array of antenna elements, the radiation pattern changes and significant deviation from the desired design performance specifications can resulted. In this paper, the detection of faults is addressed from a statistical point of view as a fault detection problem. Specifically, a statistical method rested on the GLR principle is used to detect potential faults in linear arrays. To assess the strength of the GLR-based monitoring scheme, three case studies involving different types of faults were performed. Simulation results clearly shown the effectiveness of the GLR-based fault-detection method to monitor the performance of linear antenna arrays.

  11. Terahertz antenna technology for space applications

    CERN Document Server

    Choudhury, Balamati; Jha, Rakesh Mohan

    2016-01-01

    This book explores the terahertz antenna technology towards implementation of compact, consistent and cheap terahertz sources, as well as the high sensitivity terahertz detectors. The terahertz EM band provides a transition between the electronic and the photonic regions thus adopting important characteristics from these regimes. These characteristics, along with the progress in semiconductor technology, have enabled researchers to exploit hitherto unexplored domains including satellite communication, bio-medical imaging, and security systems. The advances in new materials and nanostructures such as graphene will be helpful in miniaturization of antenna technology while simultaneously maintaining the desired output levels. Terahertz antenna characterization of bandwidth, impedance, polarization, etc. has not yet been methodically structured and it continues to be a major research challenge. This book addresses these issues besides including the advances of terahertz technology in space applications worldwide,...

  12. A Two Element Plasma Antenna Array

    Directory of Open Access Journals (Sweden)

    F. Sadeghikia

    2013-10-01

    Full Text Available This theoretical study presents the characteristics of plasma monopole antennas in the VHF/UHF range using finite difference time domain (FDTD simulation. Results show that more broadband characteristics can be obtained by increasing the diameter of the plasma tube and that the minor lobes diminish in intensity as diameter increases. Furthermore, the nulls are replaced by low level radiation. Since the collision frequency, which is a function of gas pressure, represents the loss mechanism of plasma, decreasing its value increases the gain and radar cross section (RCS of the antenna. Theoretical modeling shows that at higher plasma frequencies with respect to the signal frequency, the gain and radar cross section of the plasma antenna are high enough and that the impedance curves are altered as the plasma frequency varies. Using these preliminary studies, mutual impedance and gain of a broadside array of two parallel side-by-side plasma elements is presented.

  13. High Gain Antenna Calibration on Three Spacecraft

    Science.gov (United States)

    Hashmall, Joseph A.

    2011-01-01

    This paper describes the alignment calibration of spacecraft High Gain Antennas (HGAs) for three missions. For two of the missions (the Lunar Reconnaissance Orbiter and the Solar Dynamics Observatory) the calibration was performed on orbit. For the third mission (the Global Precipitation Measurement core satellite) ground simulation of the calibration was performed in a calibration feasibility study. These three satellites provide a range of calibration situations-Lunar orbit transmitting to a ground antenna for LRO, geosynchronous orbit transmitting to a ground antenna fer SDO, and low Earth orbit transmitting to TDRS satellites for GPM The calibration results depend strongly on the quality and quantity of calibration data. With insufficient data the calibration Junction may give erroneous solutions. Manual intervention in the calibration allowed reliable parameters to be generated for all three missions.

  14. Oxidation behavior of Hf-modified platinum aluminide coatings during thermal cycling

    Directory of Open Access Journals (Sweden)

    Liya Ye

    2018-02-01

    Full Text Available Platinum aluminide coatings with different Hf contents were fabricated by using HfCl4. The oxidation kinetics and the rumpling behavior of oxide scale were investigated. After thermal cycling, the coating with 0.46 wt% Hf showed least weight gain. With the increase of Hf content, rumpling extent of the scale decreased. Meanwhile, HfO2 preferentially formed in the scale resulting in the increase of scale thickness. The oxidation of excessive Hf even caused the spallation of the scale. The results in the present study indicate that although Hf plays an important role in decreasing rumpling extent of TGO, the oxidation of Hf decreases the adhesion of the scale. Keywords: Pt-Al coating, Hf, Oxidation, Rumpling

  15. European coordination for coastal HF radar data in EMODnet Physics

    Science.gov (United States)

    Mader, Julien; Novellino, Antonio; Gorringe, Patrick; Griffa, Annalisa; Schulz-Stellenfleth, Johannes; Montero, Pedro; Montovani, Carlo; Ayensa, Garbi; Vila, Begoña; Rubio, Anna; Sagarminaga, Yolanda

    2015-04-01

    Historically, joint effort has been put on observing open ocean, organizing, homogenizing, sharing and reinforcing the impact of the acquired information based on one technology: ARGO with profilers Argo floats, EuroSites, ESONET-NoE, FixO3 for deep water platforms, Ferrybox for stations in ships of opportunities, and GROOM for the more recent gliders. This kind of networking creates synergies and makes easier the implementation of this source of data in the European Data exchange services like EMODnet, ROOSs portals, or any applied services in the Blue economy. One main targeted improvement in the second phase of EMODnet projects is the assembling of data along coastline. In that sense, further coordination is recommended between platform operators around a specific technology in order to make easier the implementation of the data in the platforms (4th EuroGOOS DATAMEQ WG). HF radar is today recognized internationally as a cost-effective solution to provide high spatial and temporal resolution current maps (depending on the instrument operation frequency, covering from a few kilometres offshore up to 200 km) that are needed for many applications for issues related to ocean surface drift or sea state characterization. Significant heterogeneity still exists in Europe concerning technological configurations, data processing, quality standards and data availability. This makes more difficult the development of a significant network for achieving the needed accessibility to HF Radar data for a pan European use. EuroGOOS took the initiative to lead and coordinate activities within the various observation platforms by establishing a number of Ocean Observing Task Teams such as HF-Radars. The purpose is to coordinate and join the technological, scientific and operational HF radar communities at European level. The goal of the group is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of

  16. HF-induced airglow at magnetic zenith: theoretical considerations

    Directory of Open Access Journals (Sweden)

    E. V. Mishin

    2005-01-01

    Full Text Available Observations of airglow at 630nm (red line and 557.7nm (green line during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

  17. The fate of the Antennae galaxies

    Science.gov (United States)

    Lahén, Natalia; Johansson, Peter H.; Rantala, Antti; Naab, Thorsten; Frigo, Matteo

    2018-04-01

    We present a high-resolution smoothed particle hydrodynamic simulation of the Antennae galaxies (NGC 4038/4039) and follow the evolution 3 Gyr beyond the final coalescence. The simulation includes metallicity-dependent cooling, star formation, and both stellar feedback and chemical enrichment. The simulated best-match Antennae reproduce well both the observed morphology and the off-nuclear starburst. We also produce for the first time a simulated two-dimensional (2D) metallicity map of the Antennae and find good agreement with the observed metallicity of off-nuclear stellar clusters; however, the nuclear metallicities are overproduced by ˜0.5 dex. Using the radiative transfer code SKIRT, we produce multiwavelength observations of both the Antennae and the merger remnant. The 1-Gyr-old remnant is well fitted with a Sérsic profile of n = 7.07, and with an r-band effective radius of re = 1.6 kpc and velocity dispersion of σe = 180 km s-1 the remnant is located on the Fundamental Plane of early-type galaxies (ETGs). The initially blue Antennae remnant evolves on to the red sequence after ˜2.5 Gyr of secular evolution. The remnant would be classified as a fast rotator, as the specific angular momentum evolves from λRe ≈ 0.11 to 0.14 during its evolution. The remnant shows ordered rotation and a double peaked maximum in the mean 2D line-of-sight velocity. These kinematical features are relatively common amongst local ETGs and we specifically identify three local ETGs (NGC 3226, NGC 3379, and NGC 4494) in the atlas3D sample, whose photometric and kinematic properties most resemble the Antennae remnant.

  18. Dual-polarized feed antenna apparatus and method of use

    Science.gov (United States)

    Sarehraz, Mohammed (Inventor); Buckle, Kenneth A. (Inventor); Stefanakos, Elias (Inventor); Weller, Thomas (Inventor); Goswami, D. Yogi (Inventor)

    2009-01-01

    An antenna apparatus and method for the interception of randomly polarized electromagnetic waves utilizing a dual polarized antenna which is excited through a cross-slot aperture using two well-isolated orthogonal feeds.

  19. Design and optimization of LTE 1800 MIMO antenna.

    Science.gov (United States)

    Wong, Huey Shin; Islam, Mohammad Tariqul; Kibria, Salehin

    2014-01-01

    A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than -15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz-1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.

  20. On Connectivity of Wireless Sensor Networks with Directional Antennas

    Directory of Open Access Journals (Sweden)

    Qiu Wang

    2017-01-01

    Full Text Available In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models.

  1. 47 CFR 73.6025 - Antenna system and station location.

    Science.gov (United States)

    2010-10-01

    ... RADIO BROADCAST SERVICES Class A Television Broadcast Stations § 73.6025 Antenna system and station... clearly the radiation characteristics of the antenna above and below the horizontal plane. In cases where...

  2. Non-foster matching of an RFID antenna

    KAUST Repository

    Mohamed Hassan Salem, Nedime Pelin; Niver, Edip

    2011-01-01

    Novel designs of radio-frequency identification (RFID) tag antennas with better matching characteristics to achieve extended range for passive tags are investigated in ultra-high frequency (UHF) band. A microstrip dipole antenna with or without

  3. 3D Inkjet Printed Helical Antenna with Integrated Lens

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2016-01-01

    The gain of an antenna can be enhanced through the integration of a lens, although this technique has traditionally been restricted to planar antennas due to fabrication limitations of standard manufacturing processes. Here, through a unique

  4. Planar Ultrawideband Antenna with Photonically Controlled Notched Bands

    Directory of Open Access Journals (Sweden)

    Drasko Draskovic

    2013-01-01

    Full Text Available A design of a planar microstrip-fed ultrawideband (UWB printed circular monopole antenna with optically controlled notched bands is presented. The proposed antenna is composed of a circular ultrawideband patch, with an etched T-shaped slot controlled by an integrated silicon switch. The slot modifies the frequency response of the antenna suppressing 3.5–5 GHz band when the switch is in open state. The optical switch is controlled by a low-power near-infrared (808 nm laser diode, which causes the change in the frequency response of the antenna generating a frequency notch. This solution could be expanded to include several notches in the antenna frequency response achieving a fully reconfigurable UWB antenna. The antenna could be remotely controlled at large distances using optical fiber. The prototype antenna has been fully characterized to verify these design concepts.

  5. Broadband antenna for ground penetrating radar application in soil

    Science.gov (United States)

    Shebalkova, LV; Markov, MA; Romodin, VB

    2018-03-01

    The scope of the article embraces the features of design of antennas and arrays for GPR, their type and parameters and the expediency of the application of the antenna arrays in various purpose location systems of GPR.

  6. Tri-band small monopole antenna based on SRR units

    Directory of Open Access Journals (Sweden)

    Gehan Shehata

    2015-12-01

    Full Text Available In this paper a novel design for a tri-band monopole antenna coupled with metamaterial units is introduced. The proposed antenna was designed to cover WiMAX (2.5, 3.5 and WLAN (5.2 bands. In our proposal, a coplanar waveguide (CPW fed circular-disk monopole antenna is coupled with three split ring resonator (SRR units which exist on its back side. In our design a monopole antenna and SRR units are designed first to resonate at 5.2 GHz and 2.5 GHz respectively. In addition, antenna is loaded with post to force resonance at 3.5 GHz. SRR units are used for 2.5 GHz resonance to miniaturize antenna size, and our proposed antenna considered an electrically small antenna (ESA at its first resonance frequency. Simulated and measured results exhibit a good agreement that validate our design.

  7. Combline antennas for launching traveling fast waves

    International Nuclear Information System (INIS)

    Moeller, C.P.; Gould, R.W.; Phelps, D.A.; Pinsker, R.I.

    1994-01-01

    The combline structure shows promise for launching traveling fast magnetosonic waves with adjustable n parallel (3 ≤ n parallel ≤ 6) for current drive. In this paper, the dispersion and damping properties of the combline antenna with and without a Faraday shield are given. The addition of a Faraday shield which eliminates the electrostatic coupling between current straps as well as between the straps and plasma offers the advantage of eliminating the need for the lumped capacitors which are otherwise required with this structure. The results of vacuum dispersion and damping measurements on a low power model antenna are also given. (author)

  8. Frequency-agile antennas for wireless communications

    CERN Document Server

    Petosa, Aldo

    2013-01-01

    Mobile data subscriptions are expected to more than double and mobile wireless traffic to increase by more than tenfold over the next few years. Proliferation of smart phones, tablets, and other portable devices are placing greater demands for services such as web browsing, global positioning, video streaming, and video telephony. Many of the proposed solutions to deal with these demands will have a significant impact on antenna designs. Antennas with frequency agility are considered a promising technology to help implement these new solutions.This book provides readers with a sense of the cap

  9. MEMS-Reconfigurable Metamaterials and Antenna Applications

    Directory of Open Access Journals (Sweden)

    Tomislav Debogovic

    2014-01-01

    Full Text Available This paper reviews some of our contributions to reconfigurable metamaterials, where dynamic control is enabled by microelectromechanical systems (MEMS technology. First, we show reconfigurable composite right-/left-handed transmission lines (CRLH-TLs having state of the art phase velocity variation and loss, thereby enabling efficient reconfigurable phase shifters and leaky-wave antennas (LWA. Second, we present very low loss metasurface designs with reconfigurable reflection properties, applicable in reflectarrays and partially reflective surface (PRS antennas. All the presented devices have been fabricated and experimentally validated. They operate in X- and Ku-bands.

  10. A Case Study on Distributed Antenna Systems

    DEFF Research Database (Denmark)

    Sørensen, Troels Bundgaard

    2007-01-01

    Passive distributed antenna systems (DASs) consisting of distributed feeder lines or single point antennas are now often installed in large office buildings where they provide efficient coverage throughout the building. More sophisticated DASs with intelligent reuse and the ability to adapt...... is described in terms of algorithms for power allocation and access port assignment, as well as algorithms for (dynamic) channel assignment. After an outline of simulation assumptions, system capacity comparisons are given between the adaptive DAS and a system with fixed channel and access port assignment...

  11. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

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

    2011-01-01

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

  12. Antenna subset selection at multi-antenna relay with adaptive modulation

    KAUST Repository

    Choi, Seyeong

    2011-06-01

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

  13. Non-foster matching of an RFID antenna

    KAUST Repository

    Mohamed Hassan Salem, Nedime Pelin

    2011-07-01

    Novel designs of radio-frequency identification (RFID) tag antennas with better matching characteristics to achieve extended range for passive tags are investigated in ultra-high frequency (UHF) band. A microstrip dipole antenna with or without an integrated negative impedance converter designed to cancel out the antenna\\'s input capacitance at resonance frequency was designed, simulated, constructed and measured for implementation in RFID applications. © 2011 IEEE.

  14. Multiport antenna systems for space-time communications

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Alrabadi, Osama; Pelosi, Mauro

    2013-01-01

    The paper presents the concept of multiport antenna systems where multiple active and passive ports are deployed. The passive ports, implemented via tunable reactance-assisted (parasitic) antennas, can alter the far-field and near-field properties of the antenna system expressed by the antenna...... efficiency, electromagnetic coupling and spatial correlation. The system can be optimized in order to enhance the spatial multiplexing performance whereas the performance gains come at no significant additional cost and hardware complexity...

  15. Reconfigurable Patch Antenna Radiations Using Plasma Faraday Shield Effect

    OpenAIRE

    Barro , Oumar Alassane; Himdi , Mohamed; Lafond , Olivier

    2016-01-01

    International audience; This letter presents a new reconfigurable antenna associated with a plasma Faraday shield effect. The Faraday shield effect is realized by using a fluorescent lamp. A patch antenna operating at 2.45 GHz is placed inside the lamp. The performance of the reconfigurable system is observed in terms of S11, gain and radiation patterns by simulation and measurement. It is shown that by switching ON the fluorescent lamp, the gain of the antenna decreases and the antenna syste...

  16. Optimized dipole antennas on photonic band gap crystals

    International Nuclear Information System (INIS)

    Cheng, S.D.; Biswas, R.; Ozbay, E.; McCalmont, S.; Tuttle, G.; Ho, K.

    1995-01-01

    Photonic band gap crystals have been used as a perfectly reflecting substrate for planar dipole antennas in the 12--15 GHz regime. The position, orientation, and driving frequency of the dipole antenna on the photonic band gap crystal surface, have been optimized for antenna performance and directionality. Virtually no radiated power is lost to the photonic crystal resulting in gains and radiation efficiencies larger than antennas on other conventional dielectric substrates. copyright 1995 American Institute of Physics

  17. Layout and cabling considerations for a large communications antenna array

    Science.gov (United States)

    Logan, R. T., Jr.

    1993-01-01

    Layout considerations for a large deep space communications antenna array are discussed. A fractal geometry for the antenna layout is described that provides optimal packing of antenna elements, efficient cable routing, and logical division of the array into identical sub-arrays.

  18. Antenna Gain Impact on UWB Wind Turbine Blade Deflection Sensing

    DEFF Research Database (Denmark)

    Zhang, Shuai; Franek, Ondrej; Byskov, Claus

    2018-01-01

    Antenna gain impact on UWB wind turbine blade deflection sensing is studied in this paper. Simulations are applied with a 4.5-meter blade tip. The antennas with high gain (HG) and low gain (LG) in free space are simulated inside a blade. It is interesting to find that tip antennas with HG and LG...

  19. Reliable Control of Ship-mounted Satellite Tracking Antenna

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Izadi-Zamanabadi, Roozbeh; Wisniewski, Rafal

    2010-01-01

    Motorized antenna is a key element in overseas satellite telecommunication. The control system directs the on-board antenna toward a chosen satellitewhile the high sea waves disturb the antenna. Certain faults (communication system malfunction or signal blocking) cause interruption in the communi...

  20. Space vehicle electromechanical system and helical antenna winding fixture

    Science.gov (United States)

    Judd, Stephen; Dallmann, Nicholas; Guenther, David; Enemark, Donald; Seitz, Daniel; Martinez, John; Storms, Steven

    2017-12-26

    A space vehicle electromechanical system may employ an architecture that enables convenient and practical testing, reset, and retesting of solar panel and antenna deployment on the ground. A helical antenna winding fixture may facilitate winding and binding of the helical antenna.

  1. Increased operational range for implantable UHF RFID antennas

    NARCIS (Netherlands)

    Dubok, A.; Smolders, A.B.

    2014-01-01

    This paper discusses the main design challenges of implantable UHF RFID antennas in lossy environments. A novel cylindrical implantable antenna concept is presented. The proposed antenna shows good performance inside lossy environments, like a human body. The RFID tag is able to work in a range up

  2. Review of Large Spacecraft Deployable Membrane Antenna Structures

    Science.gov (United States)

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

    2017-11-01

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

  3. Global design of an active integrated antenna for millimeter wave

    OpenAIRE

    Marzolf, Eric; Drissi, M’hamed

    2001-01-01

    An active integrated antenna working in the millimeter wave has been realized in a monolithic process. The concept of active integrated antenna is first introduced, then the design of the integrated circuit based on a global approach, following electromagnetic and circuit simulations, is presented. The obtained performances of the active antenna are discussed and compared to a passive one.

  4. Inkjet printed circularly polarized antennas for GPS applications

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2014-01-01

    gain of 0.2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 3.8%. The second antenna design comprises a modified monopole in the form of an inverted L and has been termed as circularly polarized inverted L antenna (CILA). The antenna shows a gain

  5. Rapid Prototyping of Electrically Small Spherical Wire Antennas

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2014-01-01

    It is shown how modern rapid prototyping technologies can be applied for quick and inexpensive, but still accurate, fabrication of electrically small wire antennas. A well known folded spherical helix antenna and a novel spherical zigzag antenna have been fabricated and tested, exhibiting...

  6. Design of cost effective antennas for instrumentation radars

    CSIR Research Space (South Africa)

    Botha, L

    2012-09-01

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

  7. Detuning effect study of High-Q Mobile Phone Antennas

    DEFF Research Database (Denmark)

    Bahramzy, Pevand; Pedersen, Gert F.

    2015-01-01

    Number of frequency bands that have to be covered by smart phones, are ever increasing. This broadband coverage can be obtained either by using a low-Q antenna or a high-Q tunable antenna. This study investigates high-Q antennas performance when placed in proximity of the user. This study...

  8. Wide-scan dielectric dome antenna with reduced profile

    NARCIS (Netherlands)

    Gandini, E.; Silvestri, F.; Benini, A.; Gerini, G.; Martini, E.; Maci, S.; Viganò, M.C.; Toso, G.; Monni, S.

    2017-01-01

    In this contribution, a dielectric dome antenna design in Ka-band is presented. The dome antenna is based on the combination of a phased array and a dielectric lens. The goal of the combination of these structures is to enlarge the field of view of the antenna. In particular, the array is considered

  9. Electrically Small Magnetic Dipole Antennas with Magnetic Core

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Breinbjerg, Olav

    2010-01-01

    This work extends the theory of a spherical magnetic dipole antenna with magnetic core by numerical results for practical antenna configurations that excite higher-order modes besides the main TE10 spherical mode. The multiarm spherical helix (MSH) and the spherical split ring (SSR) antennas...

  10. Influence of rotation on multiphoton processes in HF

    International Nuclear Information System (INIS)

    Broeckhove, J.; Feyen, B.; Van Leuven, P.

    1994-01-01

    In this contribution, the authors are concerned with the role of rotational motion in multiphoton processes induced by a laser field of high intensity. The authors use the pseudospectral split operator method for the propagation of the quantum wave-function. The rotation is treated by decomposition of the HF wave-function in its angular momentum components

  11. lambda-3, Sandia's 100-J HF laser system

    International Nuclear Information System (INIS)

    Klein, R.A.

    1979-09-01

    Sandia's lambda-geometry intermediate electron-beam-initiated HF amplifier is described in sufficient detail such that a similar system could be designed, constructed and characterized. Items included are the design of the laser cell, magnetic field design and measurements, electron-beam calorimetry, and typical laser results

  12. Multiple excitation modes in 163Hf

    DEFF Research Database (Denmark)

    Yadav, Rachita; Ma, J.C.; Marsh, J.C.

    2014-01-01

    Excited states of Hf163 were populated using the Zr94(Ge74,5n) reaction and the decay γ rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five-quasiparticle...

  13. COPD predicts mortality in HF: the Norwegian Heart Failure Registry.

    Science.gov (United States)

    De Blois, Jonathan; Simard, Serge; Atar, Dan; Agewall, Stefan

    2010-03-01

    Chronic obstructive pulmonary disease (COPD) and chronic heart failure (HF) are common clinical conditions that share tobacco as a risk factor. Our aim was to evaluate the prognostic impact of COPD on HF patients. The Norwegian Heart Failure Registry was used. The study included 4132 HF patients (COPD, n = 699) from 22 hospitals (mean follow-up, 13.3 months). COPD patients were older, more often smokers and diabetics, less often on beta-blockers and had a higher heart rate. They were more often in New York Heart Association (NYHA) Class III or IV (COPD, 63%; no COPD, 51%), although left ventricular ejection fraction (LVEF) distribution was similar. COPD independently predicted death (adjusted hazard ratio [HR], 1.188; 95% CI: 1.015 to 1.391; P = 0.03) along with age, creatinine, NYHA Class III/IV (HR, 1.464; 95% CI: 1.286 to 1.667) and diabetes. beta-blockers at baseline were associated with improved survival in patients with LVEF < or =40% independently of COPD. COPD is associated with a poorer survival in HF patients. COPD patients are overrated in terms of NYHA class in comparison with patients with similar LVEF. Nonetheless, NYHA class remains the strongest predictor of death in these patients. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  14. Research of HF and HV circuit with Pspice

    International Nuclear Information System (INIS)

    Guo Jianjiang; Li Quanfeng; Zheng Shuxin; Li Wenjun; Tang Chuanxiang

    2005-01-01

    Transferring HF and HV pulse with 3 kinds of components is discussed. Terminal volt waves was got using the soft of Pspice when transmission line is matching of load in 3 kinds of condition. It is proved by experiments that the results got from Pspice have important values to improve experiment circuit. (authors)

  15. Impact of Antenna Placement on Frequency Domain Adaptive Antenna Array in Hybrid FRF Cellular System

    Directory of Open Access Journals (Sweden)

    Sri Maldia Hari Asti

    2012-01-01

    Full Text Available Frequency domain adaptive antenna array (FDAAA is an effective method to suppress interference caused by frequency selective fading and multiple-access interference (MAI in single-carrier (SC transmission. However, the performance of FDAAA receiver will be affected by the antenna placement parameters such as antenna separation and spread of angle of arrival (AOA. On the other hand, hybrid frequency reuse can be adopted in cellular system to improve the cellular capacity. However, optimal frequency reuse factor (FRF depends on the channel propagation and transceiver scheme as well. In this paper, we analyze the impact of antenna separation and AOA spread on FDAAA receiver and optimize the cellular capacity by using hybrid FRF.

  16. Investigation of Diagonal Antenna-Chassis Mode in Mobile Terminal LTE MIMO Antennas for Bandwidth Enhancement

    DEFF Research Database (Denmark)

    Zhang, Shuai; Zhao, Kun; Ying, Zhinong

    2015-01-01

    mechanism of the mismatch of these three bandwidth ranges is also explained. Furthermore, the diagonal antenna-chassis mode is also studied for MIMO elements in the adjacent and diagonal corner locations. As a practical example, a wideband collocated LTE MIMO antenna is proposed and measured. It covers......A diagonal antenna-chassis mode is investigated in long-term evolution multiple-input-multiple-output (LTE MIMO) antennas. The MIMO bandwidth is defined in this paper as the overlap range of the low-envelope correlation coefficient, high total efficiency, and -6-dB impedance matching bandwidths...... the bands of 740960 and 1700-2700 MHz, where the total efficiencies are better than -3.4 and -1.8 dB, with lower than 0.5 and 0.1, respectively. The measurements agree well with the simulations. Since the proposed method only needs to modify the excitation locations of the MIMO elements on the chassis...

  17. Novel Electrically Small Spherical Electric Dipole Antenna

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2010-01-01

    This paper introduces a novel electrically small spherical meander antenna. Horizontal sections of the meander are composed of wire loops, radii of which are chosen so that the whole structure is conformal to a sphere of radius a. To form the meander the loops are connected by wires at a meridian...

  18. Innovation in wearable and flexible antennas

    CERN Document Server

    Khaleel, Haider

    2014-01-01

    This book covers the design, numerical simulation, state of the art fabrication processes, qualitative and quantitative tests, and measurement techniques of wearable and flexible antennas of various topologies, such as: Printed Monopoles, Micropoles and Microstrips. It serves as a vital reference source for scientists and engineers in this field.

  19. Topology Optimization of Sub-Wavelength Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Sigmund, Ole

    2011-01-01

    We propose a topology optimization strategy for the systematic design of a three-dimensional (3D), conductor-based sub-wavelength antenna. The post-processed finite-element (FE) models of the optimized structure are shown to be self-resonant, efficient and exhibit distorted omnidirectional...

  20. Modeling and control of antennas and telescopes

    CERN Document Server

    Gawronski, Wodek

    2008-01-01

    The book shows, step-by-step, the design, implementation, and testing of the antenna/telescope control system, from the design stage (analytical model) to fine tuning of the RF beam pointing (monopulse and conscan). It includes wide use of Matlab and Simulink..

  1. Small inductor Loaded mobile phone Antenna

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2004-01-01

    In this paper a size reduction technique of the Planar Inverted F Antenna (PIFA) is presented. Using an 18 nH lumped inductor in addition to a small 0.3 cm3 PIFA located on a 5 mm thick dielectric foam above a 40 x 100 mm2 ground plane it is possible to reduce the resonant frequency by 33 % for a...

  2. Matching of Tore Supra ICRH antennas

    International Nuclear Information System (INIS)

    Ladurelle, L.; Beaumont, B.; Kuus, H.; Lombard, G.

    1994-01-01

    An automatic matching method is described for Tore Supra ICRH antennas based on impedance variations seen at their feed points. Error signals derived from directional voltage and phase measurements in the feeder allow to control the matching capacitors values for optimal power transmission. (author) 5 refs.; 9 figs

  3. Microwave Correlation Measurement Crossed-pair Antennas ...

    African Journals Online (AJOL)

    We propose here new processes, an add and square correlation radiometer and the non-resonant perturbation, which thoroughly investigated for different muscle phantom materials to define the optimum penetration depth of the electromagnetic field at fixed distance between the antennas. Keywords: Microwave correlation ...

  4. Stochastic Beamforming via Compact Antenna Arrays

    DEFF Research Database (Denmark)

    Alrabadi, Osama; Pedersen, Gert Frølund

    2012-01-01

    The paper investigates the average beamforming (BF) gain of compact antenna arrays when statistical channel knowledge is available. The optimal excitation (precoding vector) and impedance termination that maximize the average BF gain are a compromise between the ones that maximize the array...

  5. Antenna Design for Diversity and MIMO Application

    DEFF Research Database (Denmark)

    Ying, Zhinong; Chiu, Chi-Yuk; Zhao, Kun

    2015-01-01

    Recently, multiple-input multiple-output (MIMO) technology and diversity have attracted much attention both in industry and academia due to high data rate and high spectrum efficiency. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diver...

  6. Antenna size reduction in microalgae mass culture

    NARCIS (Netherlands)

    Mooij, de T.

    2016-01-01

    The thesis describes the potential of microalgae with a reduced light harvesting antenna for biomass production under mass culture conditions (high biomass density, high light intensity). Theoretically, the lower chlorophyll content reduces the light harvesting capacity and with that the amount

  7. Precision Antenna Measurement System (PAMS) Engineering Services

    Science.gov (United States)

    1978-04-01

    8217) = receiving antenna gain for vertical polarization. The total direct signal power is Following Beck /narn and Spizzachino , the specular component...method may be valid for the problem. Very often, however, the physical optics 92 approach baaed on a solution of the wave equation will have to

  8. Microelectromechanical Switches for Phased Array Antennas

    Science.gov (United States)

    Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

    2000-01-01

    Preliminary results are presented on the fabrication and testing of a MicroElectro-Mechanical (MEM) microstrip series switch. This switch is being developed for use in a K-band phased array antenna that NASA will use for communication links in its Earth orbiting satellites. Preliminary insertion loss and isolation measurements are presented.

  9. 47 CFR 101.115 - Directional antennas.

    Science.gov (United States)

    2010-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE... The minimum front-to-back ratio shall be 38 dBi. 13 Mobile, except aeronautical mobile, stations need... cases of potential interference, an antenna will not be considered to meet Standard A unless the...

  10. Self Configurable Intelligent Distributed Antenna System

    DEFF Research Database (Denmark)

    Kumar, Ambuj; Mihovska, Albena Dimitrova; Prasad, Ramjee

    2016-01-01

    with their respective base stations, spectrum pooling and management at antenna end is not efficient. The situation worsens in Heterogeneous and Dense-net conditions in an Area of Interest (AoI). In this paper, we propose a DAS based intelligent architecture referred to as Self Configurable Intelligent Distributed...

  11. Heating profiles on ICRF antenna Faraday shields

    International Nuclear Information System (INIS)

    Taylor, D.J.; Baity, F.W.; Hahs, C.L. Riemer, B.W.; Ryan, D.M.; Williamson, D.E.

    1992-01-01

    Poor definition of the heating profiles that occur during normal operation of Faraday shields for ion cyclotron resonant frequency (ICRF) antennas has complicated the mechanical design of ICRF system components. This paper reports that at Oak Ridge National Laboratory (ORNL), Faraday shield analysis is being used in defining rf heating profiles. In recent numerical analyses of proposed hardware for the Burning Plasma Experiment (BPX) and DIII-D, rf magnetic fields at Faraday shield surfaces were calculated, providing realistic predictions of the induced skin currents flowing on the shield elements and the resulting dissipated power profile. Detailed measurements on mock-ups of the Faraday shields for DIII-D and the Tokamak Fusion Test Reactor (TFTR) confirmed the predicted magnetic field distributions. A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the DIII-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed

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

    KAUST Repository

    Hussain, Rifaqat; Sharawi, Mohammad S.

    2015-01-01

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

  13. Restoring Low Sidelobe Antenna Patterns with Failed Elements in a Phased Array Antenna

    Science.gov (United States)

    2016-02-01

    optimum low sidelobes are demonstrated in several examples. Index Terms — Array signal processing, beams, linear algebra , phased arrays, shaped...beam antennas. I. INTRODUCTION For many phased array antenna applications , low spatial sidelobes are required, and it is desirable to maintain...represented by a linear combination of low sidelobe beamformers with no failed elements, ’s, in a neighborhood around under the constraint that the linear

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

    Science.gov (United States)

    Rogers, Lesley J; Vallortigara, Giorgio

    2008-06-04

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

  15. Variability of Surface Reflection Amplitudes of GPR Horn Antenna Depending on Distance between Antenna and Surface

    Directory of Open Access Journals (Sweden)

    Komačka Jozef

    2016-05-01

    Full Text Available The study focused on variability of surface reflections amplitudes of GPR horn antenna in relation to distance between an antenna and a surface is presented in the paper. The air-coupled antenna with the central frequency of 1 GHz was used in the investigation. Four types of surfaces (dry pavement, wet pavement, metal plate and composite layer from gypsum and wood were tested. The distance of antenna above the surfaces was changed in the range from 37.5 cm to 53.5 cm. The amplitudes of negative and positive peaks and their variability were analysed in relation to the distance of antenna above the surfaces. Moreover, the influence of changes in the peaks of negative and positive amplitudes on the total amplitudes was assessed. It was found out the amplitudes of negative peaks for all investigated surfaces were relatively consistent in the range from 40.5 cm to 48.5 cm and the moderate decline was identified in the case of amplitudes of positive peaks in the range of distances from 37.5 cm to 51.5 cm. This decline influences the tendency of total amplitudes. Based on the results of analysis it can be stated the distance of air-coupled antenna above the surface can influence the value of total amplitude and the differences depend on the type of surface.

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

    Directory of Open Access Journals (Sweden)

    Lesley J Rogers

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

  17. Planar Near-Field Measurements of Ground Penetrating Radar Antennas

    DEFF Research Database (Denmark)

    Meincke, Peter; Hansen, Thorkild

    2004-01-01

    Planar near-field measurements are formulated for a general ground penetrating radar (GPR) antenna. A total plane-wave scattering matrix is defined for the system consisting of the GPR antenna and the planar air-soil interface. The transmitting spectrum of the GPR antenna is expressed in terms...... of measurements obtained with a buried probe as the GPR antenna moves over a scan plane on the ground. A numerical example in which the scan plane is finite validates the expressions for the spectrum of the GPR antenna....

  18. Full-duplex MIMO system based on antenna cancellation technique

    DEFF Research Database (Denmark)

    Foroozanfard, Ehsan; Franek, Ondrej; Tatomirescu, Alexandru

    2014-01-01

    The performance of an antenna cancellation technique for a multiple-input– multiple-output (MIMO) full-duplex system that is based on null-steering beamforming and antenna polarization diversity is investigated. A practical implementation of a symmetric antenna topology comprising three dual......-polarized patch antennas operating at 2.4 GHz is described. The measurement results show an average of 60 dB self-interference cancellation over 200 MHz bandwidth. Moreover, a decoupling level of up to 22 dB is achieved for MIMO multiplexing using antenna polarization diversity. The performance evaluation...

  19. Quench observation using quench antennas on RHIC IR quadrupole magnets

    International Nuclear Information System (INIS)

    Ogitsu, T.; Terashima, A.; Tsuchiya, K.; Ganetis, G.; Muratore, J.; Wanderer, P.

    1995-01-01

    Quench observation using quench antennas is now being performed routinely on RHIC dipole and quadrupole magnets. Recently, a quench antenna was used on a RHIC IR magnet which is heavily instrumented with voltage taps. It was confirmed that the signals detected in the antenna coils do not contradict the voltage tap signals. The antenna also detects a sign of mechanical disturbance which could be related to a training quench. This paper summarizes signals detected in the antenna and discusses possible causes of these signals

  20. Quench observation using quench antennas on RHIC IR quadrupole magnets

    International Nuclear Information System (INIS)

    Ogitsu, T.; Terashima, A.; Tsuchiya, K.; Ganetis, G.; Muratore, J.; Wanderer, P.

    1996-01-01

    Quench observation using quench antennas is now being performed routinely on RHIC dipole and quadrupole magnets. Recently, a quench antenna was used on a RHIC IR magnet which is heavily instrumented with voltage taps. It was confirmed that the signals detected in the antenna coils do not contradict the voltage tap signals. The antenna also detects a sign of mechanical disturbance which could be related to a training quench. This paper summarizes signals detected in the antenna and discusses possible causes of these signals

  1. Conformal Lightweight Antenna Structures for Aeronautical Communication Technologies

    Science.gov (United States)

    Meador, Mary Ann

    2017-01-01

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

  2. PROSPECTS FOR THE DEVELOPMENT OF PHASED ANTENNA ARRAYS

    Directory of Open Access Journals (Sweden)

    A. P. Dzuba

    2013-01-01

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

  3. Mutual Coupling Effects on Pattern Diversity Antennas for MIMO Femtocells

    Directory of Open Access Journals (Sweden)

    Yue Gao

    2010-01-01

    Full Text Available Diversity antennas play an important role in wireless communications. However, mutual coupling between multiple ports of a diversity antenna has significant effects on wireless radio links and channel capacity. In this paper, dual-port pattern diversity antennas for femtocell applications are proposed to cover GSM1800, UMTS, and WLAN frequency bands. The channel capacities of the proposed antennas and two ideal dipoles with different mutual coupling levels are investigated in an indoor environment. The relation between mutual coupling and channel capacity is observed through investigations of these antennas.

  4. Large space antenna concepts for ESGP

    Science.gov (United States)

    Love, Allan W.

    1989-01-01

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

  5. Mode Theory of Multi-Armed Spiral Antennas and Its Application to Electronic Warfare Antennas

    Science.gov (United States)

    Radway, Matthew J.

    Since their invention about 55 years ago, spiral antennas have earned a reputation for providing stable impedance and far-field patterns over multi-decade frequency ranges. For the first few decades these antennas were researched for electronic warfare receiving applications, primarily in the 2-18 GHz range. This research was often done under conditions of secrecy, and often by private contractors who did not readily share their research, and now have been defunct for decades. Even so, the body of literature on the two-armed variant of these antennas is rich, often leading non-specialists to the misconception that these antennas are completely understood. Furthermore, early work was highly experimental in nature, and was conducted before modern data collection and postprocessing capabilities were widespread, which limited the range of the studies. Recent research efforts have focused on extending the application of spirals into new areas, as well as applying exotic materials to `improve' their performance and reduce their size. While interesting results have been obtained, in most instances these were incomplete, often compromising the frequency independent nature of these antennas. This thesis expands the role of the multi-armed spiral outside of its traditional niche of receive-only monopulse direction finding. As a first step, careful study of the spiral-antenna mode theory is undertaken with particular attention paid to the concepts of mode filtering and modal decomposition. A technique for reducing the modal impedance of high arm-count spirals is introduced. The insights gained through this theoretical study are first used to improve the far-field performance of the coiled-arm spiral antenna. Specifically, expanding the number of arms on a coiled arm spiral from two to four while providing proper excitation enables dramatically improved broadside axial ratio and azimuthal pattern uniformity. The multiarming technique is then applied to the design of an antenna

  6. Nanosized Hydroxyapatite Precipitation on the Ti—30Ta—xHf Alloys.

    Science.gov (United States)

    Lee, Kang; Jang, Jae- In; Han-Cheol, Choe

    2017-04-01

    In this study, we prepared hydroxyapatite (HAp) layer on the alkali treated Ti–30Ta–xHf alloys using electrochemical deposition method. Ti–30Ta–xHf alloys was anodized in 5 M NaOH solution at 0.3 A for 10 min. Alkali treated Ti–30Ta–xHf surface formed by anodization step which acted as templates and anchorage for growth of the HAp during subsequent pulsed electrochemical deposition process at 85 °C. The phase and morphologies of deposited HAp layer were affected by the Hf contents of Ti–30Ta–xHf alloys. The nano-scale rod-like HAp layer was formed on untreated Ti–30Ta–xHf alloys with partially low crystallinity. In the case of alkali treated Ti–30Ta–xHf, nano-sized needle-like layers were transferred to nano-flake surface and denser morphology as Hf content increased.

  7. HF Radar observations of the Dardanelles outflow current in North Eastern Aegean using validated WERA HF radar data

    Directory of Open Access Journals (Sweden)

    Z. KOKKINI

    2014-12-01

    Full Text Available A two-site WERA HF radar station was installed in November 2009 at the eastern coast of Lemnos Island in North Aegean Sea, aiming to monitor the surface inflow of Black Sea waters exiting from the Dardanelles Strait, as well as to constitute a coastal management tool for incidents of oil-pollution or save-and-rescue operations. Strong interference by foreign transmissions is a source of noise deteriorating the quality of the backscattered signal, thus significantly reducing the HF radar’s effective data return rate. In order to ameliorate this problem, further quality-control and data gap interpolating procedures have been developed and applied, to be used in addition to the procedures incorporated and used by the manufacturer’s signal processing software. The second-level processing involves traditional despiking in the temporal domain, preceding Empirical Orthogonal Function analysis. The latter is used not only to filter high-frequency noise but also to fill data gaps in time and space. The data reconstruction procedure has been assessed via comparison of (a HF radial with CODE-type drifter radial velocities as well as (b HF-derived virtual drifter tracks with actual drifter tracks. The main circulation features and their variability, as revealed by the reconstructed fields, are presented.

  8. Computer-Automated Evolution of Spacecraft X-Band Antennas

    Science.gov (United States)

    Lohn, Jason D.; Homby, Gregory S.; Linden, Derek S.

    2010-01-01

    A document discusses the use of computer- aided evolution in arriving at a design for X-band communication antennas for NASA s three Space Technology 5 (ST5) satellites, which were launched on March 22, 2006. Two evolutionary algorithms, incorporating different representations of the antenna design and different fitness functions, were used to automatically design and optimize an X-band antenna design. A set of antenna designs satisfying initial ST5 mission requirements was evolved by use these algorithms. The two best antennas - one from each evolutionary algorithm - were built. During flight-qualification testing of these antennas, the mission requirements were changed. After minimal changes in the evolutionary algorithms - mostly in the fitness functions - new antenna designs satisfying the changed mission requirements were evolved and within one month of this change, two new antennas were designed and prototypes of the antennas were built and tested. One of these newly evolved antennas was approved for deployment on the ST5 mission, and flight-qualified versions of this design were built and installed on the spacecraft. At the time of writing the document, these antennas were the first computer-evolved hardware in outer space.

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

    Science.gov (United States)

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

    1992-01-01

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

  10. Inkjet printed circularly polarized antennas for GPS applications

    KAUST Repository

    Farooqui, Muhammad Fahad

    2014-07-01

    Two novel, inkjet printed circularly polarized antenna designs are presented for GPS applications. First antenna design comprises a planar monopole which has been made circularly polarized by the introduction of an L-shaped slit. The antenna shows a gain of 0.2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 3.8%. The second antenna design comprises a modified monopole in the form of an inverted L and has been termed as circularly polarized inverted L antenna (CILA). The antenna shows a gain of -2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 4.1%. Both the antenna designs are attractive for mobile applications.

  11. Plasmonic-Resonant Bowtie Antenna for Carbon Nanotube Photodetectors

    Directory of Open Access Journals (Sweden)

    Hongzhi Chen

    2012-01-01

    Full Text Available The design of bowtie antennas for carbon nanotube (CNT photodetectors has been investigated. CNT photodetectors have shown outstanding performance by using CNT as sensing element. However, detection wavelength is much larger than the diameter of the CNT, resulting in small fill factor. Bowtie antenna can confine light into a subwavelength volume based on plasmonic resonance, thus integrating a bowtie antenna to CNT photodetectors can highly improve photoresponse of the detectors. The electric field enhancement of bowtie antennas was calculated using the device geometry by considering fabrication difficulties and photodetector structure. It is shown that the electric field intensity enhancement increased exponentially with distance reduction between the CNT photodetector to the antenna. A redshift of the peak resonance wavelength is predicted due to the increase of tip angles of the bowtie antennas. Experimental results showed that photocurrent enhancement agreed well with theoretical calculations. Bowtie antennas may find wide applications in nanoscale photonic sensors.

  12. Analysis of Microstrip Line Fed Patch Antenna for Wireless Communications

    Directory of Open Access Journals (Sweden)

    Singh Ashish

    2017-11-01

    Full Text Available In this paper, theoretical analysis of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator is presented. The proposed antenna shows that the dualband operation depends on gap between parasitic element, split-ring resonator, length and width of microstrip line. It is found that antenna resonates at two distinct resonating modes i.e., 0.9 GHz and 1.8 GHz for lower and upper resonance frequencies respectively. The antenna shows dual frequency nature with frequency ratio 2.0. The characteristics of microstrip line fed rectangular patch antenna loaded with parasitic element and split-ring resonator antenna is compared with other prototype microstrip line fed antennas. Further, the theoretical results are compared with simulated and reported experimental results, they are in close agreement.

  13. Evaluation of detectable angle of mid-infrared slot antennas

    Science.gov (United States)

    Obara, R.; Horikawa, J.; Shimakage, H.; Kawakami, A.

    2017-07-01

    For evaluations of a mid-infrared (MIR) detectors with antenna, we constructed an angular dependence measurement system of the antenna properties. The fabricated MIR detector consisted of twin slot antennas and a bolometer. The area of the slot antennas was designed to be 2.6 × 0.2 μm2 as to resonate at 61 THz, and they were located parallel and separated 1.6 μm each other. The bolometer was fabricated using by a 7.0-nm thick NbN thin film, and located at the center of the twin antennas. We measured polarization angle dependence and directivity, and showed that the MIR antennas have polarization dependence and directivity like radiofrequency antennas.

  14. Nanotube formation and morphology change of Ti alloys containing Hf for dental materials use

    International Nuclear Information System (INIS)

    Jeong, Yong-Hoon; Lee, Kang; Choe, Han-Cheol; Ko, Yeong-Mu; Brantley, William A.

    2009-01-01

    In this paper, Ti-Hf (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting, and subjected to heat treatment for 24 h at 1000 o C in an argon atmosphere. Formation of surface nanotubes was achieved by anodizing a Ti-Hf alloy in 1.0 M H 3 PO 4 electrolytes with small amounts of NaF at room temperature. Microstructures of the alloys and nanotube morphology were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The homogenized Ti-Hf alloys had a needle-like microstructure of α phase, and nanotubes formed on Ti-xHf alloys had the anatase phase after treatment that promoted crystallization. Uniform nanotubes formed for Hf contents up to 20 wt.%. Irregular nanotubes formed on the Ti-30Hf and Ti-40Hf alloys. The structure of the irregular layers on the Ti-30Hf and Ti-40Hf alloys had nanotubes of two sizes. Increasing the Hf content in Ti led to the formation of nanotubes with more narrow size. The pores in the nanotubes typically had a diameter ranging from 80-120 nm and a length of approximately 1.7 μm. It is concluded that nanotube morphology on Ti-Hf alloys can controlled by varying the amount of Hf.

  15. 40 CFR 180.1273 - Beauveria bassiana HF23; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Beauveria bassiana HF23; exemption... FOOD Exemptions From Tolerances § 180.1273 Beauveria bassiana HF23; exemption from the requirement of a tolerance. Residues of Beauveria bassiana HF23 are exempt from the requirement of a tolerance on all food...

  16. Photon strength function in the Hf-181 nucleus by method of two-step cascade

    International Nuclear Information System (INIS)

    Le Hong Khiem

    2003-01-01

    The applicability of sum-coincidence measurements of two-step cascade gamma ray spectra determining Photon Strength Function (PSF) of Hf-181 induced from Hf-180 (n,2γ) Hf-181 reaction is presented. Up to 80% intensity of the primary gamma ray transitions in a wide energy range have been deduced and compared to model calculation. (author)

  17. HF turbulence as a source of novel diagnostics tool for space plasma

    International Nuclear Information System (INIS)

    Rothkaehl, H.; Klos, Z.; Thide, B.; Bergman, J.

    2005-01-01

    The T type of turbulence and instabilities can be produced by a source of free energy in the form of natural and anthropogenic perturbation. Space turbulence acts as a tracer of the various physical processes acting in these regions and gives access to them, but on the other side it disturbs the propagation of radio waves and the ability of detecting targets of interests. To understand the property of solar terrestrial environment and to develop a quantitative model of the magnetosphere-ionosphere-thermosphere subsystem, which is strongly coupled via the electric field, particle precipitation, heat flows and small scale interaction, it is necessary to design and build new generation multipoint and different type sensor diagnostics, as proposed by LOFAR/LOIS facility in complementary of space borne satellite experiments. Ground based multi frequency and multi polarization LOIS clusters antennas and clusters observations in the in the space should be helpful in achieving to solve problems of space physics and described long term environmental changes. The real-time access to gathered based data, relevant to the impact of environment physical condition on communications and global positioning system, will create the possibility to improve quality of different type space related services. Simultaneously investigation and monitoring of Earth environment will be coordinated with space borne experiment COMPAS 2 experiment. The new design radio spectrometer will be designed to investigate the still largely unknown mechanisms which govern these turbulent interactions natural and man-made origin. The main aim of this presentation is to show the general architecture of LOIS and COMPAS 2 experiment and its scientific challenges. It will be emphasize the description of electromagnetic Earth environments in HF range as well. (author)

  18. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Science.gov (United States)

    Milan, S. E.; Jones, T. B.; Robinson, T. R.; Thomas, E. C.; Yeoman, T. K.

    1997-01-01

    Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north) of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter. Acknowledgements. The authors are grateful to Prof. D. J. Southwood (Imperial College, London), J. C. Samson (University of Alberta, Edmonton), L. J. Lanzerotti (AT&T Bell Laboratories), A. Wolfe (New York City Technical College) and to Dr. M. Vellante (University of LÁquila) for helpful discussions. They also thank Dr. A. Meloni (Istituto Nazionale di Geofisica, Roma) who made available geomagnetic field observations from LÁquila Geomagnetic Observatory. This research activity at LÁquila is supported by MURST (40% and 60% contracts) and by GIFCO/CNR. Topical Editor K.-H. Glaßmeier thanks C. Waters and S. Fujita for their help in evaluating this paper.-> Correspondence to :P. Francia->

  19. Action mechanism of hydrogen gas on deposition of HfC coating using HfCl{sub 4}-CH{sub 4}-H{sub 2}-Ar system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yalei, E-mail: yaleipm@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); School of Metallurgy and Environment, Central South University, Changsha, 410083 (China); Li, Zehao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); Xiong, Xiang, E-mail: xiongx@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China); Li, Xiaobin [School of Metallurgy and Environment, Central South University, Changsha, 410083 (China); Chen, Zhaoke; Sun, Wei [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083 (China)

    2016-12-30

    Highlights: • HfC coatings were deposited on C/C composites by LPCVD using HfCl4-CH4-H2-Ar system. • Action mechanism of H2 on structure and growth behavior of HfC coating was studied. • Increased H2 concentration leads to transformation in growth mechanism of coating. - Abstract: Hafnium carbide coatings were deposited on carbon/carbon composites by low pressure chemical vapor deposition using HfCl{sub 4}-CH{sub 4}-H{sub 2}-Ar system. The microstructure, mechanical and ablation resistance performance of HfC coatings deposited with various H{sub 2} concentrations were investigated. The effect of hydrogen gas on the deposition of HfC coating was also discussed. Results show that all of the deposited coatings are composed of single cubic HfC phase, the hydrogen gas acted as a crucial role in determining the preferred orientation, microstructure and growth behavior of HfC coatings. During the deposition process, the gas phase supersaturation of the reaction species can be controlled by adjusting the hydrogen gas concentration. When deposited with low hydrogen gas concentration, the coating growth was dominated by the nucleation of HfC, which results in the particle-stacked structure of HfC coating. Otherwise, the coating growth was dominated by the crystal growth at high hydrogen gas concentration, which leads to the column-arranged structure of HfC coating. Under the ablation environment, the coating C2 exhibits better configurational stability and ablation resistance. The coating structure has a significant influence on the mechanical and ablation resistance properties of HfC coating.

  20. Study on the adducts formation of Zr and Hf chelates

    International Nuclear Information System (INIS)

    Ree, Chin Taik; Jung, Young Sam; Park, Jun Kown

    1986-01-01

    The synergistic effect observed in Zr(IV) and Hf(IV) extraction from strong perchloric acid solutions by the mixtures of 2-Thenoyltri-fluoroacetone(TTA) and Octanols is shown to be caused by the formation of a mixed complex, M(TTA) 3 XS (M=Zr(IV), HF(IV), X=ClO 4 - , S=Octanol). One of the four TTA molecules coordinated at lower HClO 4 concentration to the metal as bidendate ligand seems to be changed to monodendate due to increasing HClO 4 concentration. The monodenate TTA ligand leaves the coordination site, finally, due to the activity of perchlorate at higher concentration and the additional coordination of an Octanol molecule seems to be allowed to the vaccant site which shows the synergistic extraction phenomena. (Author)

  1. The anisotropy of Hf diffusion in α-Zr

    International Nuclear Information System (INIS)

    Hood, G.M.; Zou, H.; Roy, J.A.; Schultz, R.J.; Matsuura, N.; Jackson, J.A.

    1995-07-01

    Hf diffusion coefficients (D) have been measured in the temperature interval 870-1100 K, in directions parallel (D pa ) and perpendicular (D pe ) to the c-axis of double-faced, single crystal specimens of both high-purity (HP) and nominally pure (NP) α-Zr single crystals. The diffusion profiles were measured by secondary ion mass spectrometry. Hf diffusion in HP α-Zr is characterised by an activation energy of about 3.0 eV and a pre-exponential factor of about 10 -5 m 2 /s. The anisotropy ratio, D pa /D pe is ∼ 1.0 for the NP specimens. A dependence of D on diffusion time/depth is indicated for some NP experiments on NP Zr. (author). 7 refs., 2 tabs., 3 figs

  2. First demonstration of HF-driven ionospheric currents

    Science.gov (United States)

    Papadopoulos, K.; Chang, C.-L.; Labenski, J.; Wallace, T.

    2011-10-01

    The first experimental demonstration of HF driven currents in the ionosphere at low ELF/ULF frequencies without relying in the presence of electrojets is presented. The effect was predicted by theoretical/computational means in a recent letter and given the name Ionospheric Current Drive (ICD). The effect relies on modulated F-region HF heating to generate Magneto-Sonic (MS) waves that drive Hall currents when they reach the E-region. The Hall currents inject ELF waves into the Earth-Ionosphere waveguide and helicon and Shear Alfven (SA) waves in the magnetosphere. The proof-of-concept experiments were conducted using the HAARP heater in Alaska under the BRIOCHE program. Waves between 0.1-70 Hz were measured at both near and far sites. The letter discusses the differences between ICD generated waves and those relying on modulation of electrojets.

  3. Picture analysis in CT-HF and its CT photographs

    International Nuclear Information System (INIS)

    Kubota, Kazuo; Kohirasawa, Hideo; Shinojima, Masayasu; Tokui, Mitsuru; Seo, Kunihiko.

    1980-01-01

    CT (computed tomography) apparatus is rarely used yet in the field of dentistry, though it seems useful. It is possibly because of the artefacts caused by the metallic parts attached to teeth, the large partial volume effect due to many bones and the problems of positioning and reproducibility. After considering the various requirements of the CT apparatuses in dental field, CT-HF (of T/R type) was chosen as such apparatus, and installed as the first in dentistry. In the CT-HF apparatus, the inner diameter of the gantry is up to 300 mm, and the position of a tomographic plane is only 40 mm away from the front of gantry. Mainly the usefulness of scanography in positioning and the usefulness of the CT apparatus in the picture analysis and processing in dental field are described. (J.P.N.)

  4. Fe substitution and pressure effects on superconductor Re6Hf

    Science.gov (United States)

    Yang, Jinhu; Guo, Yang; Wang, Hangdong; Chen, Bin

    2018-04-01

    Polycrystalline samples of (Re1-xFex) 6Hf were synthesized by arc-melting method and the phase purity of the samples was confirmed by powder X-ray diffraction method. In this paper, we report the Fe substitution and pressure effect on non-centrosymmetric superconductor Re6Hf. The superconducting transition temperature, TC, is confirmed by the measurements of magnetic susceptibility, electrical resistivity for x ≤ 0.22 samples with the temperature down to 2 K. We find that the TC is suppressed with the increase of Fe content. The upper critical field Hc2 is larger than the value predicted by the WHH theory and shows a linear temperature dependence down to 2 K. When upon the application of external pressure up to 2.5 GPa, the TC decreases monotonically at a rate dlnTC/dP of 0.01 GPa-1.

  5. Comparison between HF radar current data and moored ADCP currentmeter

    International Nuclear Information System (INIS)

    Cosoli, S.

    2005-01-01

    A preliminary assessment of accuracy of a two-sites shore-based HF Radar network along the Venice Lagoon littoral was attempted by means of comparison with a 57.5 day-long ADCP current time series for the period September-October 2002. Results showed that radar measurements were accurate ( O . The main differences between the HF radar and surface ADCP currents can be explained in terms of random errors affecting the measurement technique and the daily sea breeze forcing, since low-pass filtering of current time series significantly improved the correlation and decreased the RMS of the differences between the two measured data set. Comparison of the semidiurnal (M2, S2) tidal band suggested good agreement between tidal ellipse amplitudes. Wind forcing on a daily time-scale (sea-breeze) was associated with larger differences between radar and ADCP currents at a diurnal band due to the presence of a vertical shear in the surface layer

  6. Closed cycle high-repetition-rate pulsed HF laser

    Science.gov (United States)

    Harris, Michael R.; Morris, A. V.; Gorton, Eric K.

    1997-04-01

    The design and performance of a closed cycle high repetition rate HF laser is described. A short pulse, glow discharge is formed in a 10 SF6:1 H2 gas mixture at a total pressure of approximately 110 torr within a 15 by 0.5 by 0.5 cm3 volume. Transverse, recirculated gas flow adequate to enable repetitive operation up to 3 kHz is imposed by a centrifugal fan. The fan also forces the gas through a scrubber cell to eliminate ground state HF from the gas stream. An automated gas make-up system replenishes spent gas removed by the scrubber. Typical mean laser output powers up to 3 W can be maintained for extended periods of operation.

  7. Performance Analysis of HF Band FB-MC-SS

    Energy Technology Data Exchange (ETDEWEB)

    Hussein Moradi; Stephen Andrew Laraway; Behrouz Farhang-Boroujeny

    2016-01-01

    Abstract—In a recent paper [1] the filter bank multicarrier spread spectrum (FB-MC-SS) waveform was proposed for wideband spread spectrum HF communications. A significant benefit of this waveform is robustness against narrow and partial band interference. Simulation results in [1] demonstrated good performance in a wideband HF channel over a wide range of conditions. In this paper we present a theoretical analysis of the bit error probably for this system. Our analysis tailors the results from [2] where BER performance was analyzed for maximum ration combining systems that accounted for correlation between subcarriers and channel estimation error. Equations are give for BER that closely match the simulated performance in most situations.

  8. The Use of Conductive Ink in Antenna Education and Design

    Science.gov (United States)

    Addison, David W.

    Conductive ink from a printer allows for the fabrication of conductive material with tight tolerances without the cost and time of chemical etching. This paper explores the use of AGIC printable conductive ink on a paper substrate as design tool for antennas as well as classroom use in antenna education. The antenna designs satisfy the requirements of a compact Global Navigation Satellite System (GNSS) antenna while showing a competitive performance within the current market. One best design is shown along with three other structures. These antennas consist of a bowtie cross-dipole over a reflective disc with conductive-ink grounded structures. In addition to the GNSS antennas, a linear elliptical dipole over a reflective disc with conductive grounded structures is presented. This elliptical antenna design attempts to find the maximum impedance bandwidth beyond the GNSS band. The inexpensive nature of conductive ink allows for its use in a classroom to demonstrate antenna behavior as part of antenna education. An inexpensive approach to the patch antenna using conductive ink is described and paired with a system made of off-the-shelf parts. The system is capable of measuring the power of the received signal. The received signal measurement is not as accurate as using a anechoic chamber but pattern details are visible. This is used to demonstrate aspects of the Friis transmission equation such as distance, polarization, radiation pattern shape, and loss.

  9. The Greenland Telescope (GLT): antenna status and future plans

    Science.gov (United States)

    Raffin, Philippe; Algaba-Marcosa, Juan Carlos; Asada, Keiichi; Blundell, Raymond; Burgos, Roberto; Chang, Chih-Cheng; Chen, Ming-Tang; Christensen, Robert; Grimes, Paul K.; Han, C. C.; Ho, Paul T. P.; Huang, Yau-De; Inoue, Makoto; Koch, Patrick M.; Kubo, Derek; Leiker, Steve; Liu, Ching-Tang; Martin-Cocher, Pierre; Matsushita, Satoki; Nakamura, Masanori; Nishioka, Hiroaki; Nystrom, George; Paine, Scott N.; Patel, Nimesh A.; Pradel, Nicolas; Pu, Hung-Yi; Shen, H.-Y.; Snow, William; Sridharan, Tirupati K.; Srinivasan, Ranjani; Tong, Edward; Wang, Jackie

    2014-07-01

    The ALMA North America Prototype Antenna was awarded to the Smithsonian Astrophysical Observatory (SAO) in 2011. SAO and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), SAO's main partner for this project, are working jointly to relocate the antenna to Greenland to carry out millimeter and submillimeter VLBI observations. This paper presents the work carried out on upgrading the antenna to enable operation in the Arctic climate by the GLT Team to make this challenging project possible, with an emphasis on the unexpected telescope components that had to be either redesigned or changed. Five-years of inactivity, with the antenna laying idle in the desert of New Mexico, coupled with the extreme weather conditions of the selected site in Greenland have it necessary to significantly refurbish the antenna. We found that many components did need to be replaced, such as the antenna support cone, the azimuth bearing, the carbon fiber quadrupod, the hexapod, the HVAC, the tiltmeters, the antenna electronic enclosures housing servo and other drive components, and the cables. We selected Vertex, the original antenna manufacturer, for the main design work, which is in progress. The next coming months will see the major antenna components and subsystems shipped to a site of the US East Coast for test-fitting the major antenna components, which have been retrofitted. The following step will be to ship the components to Greenland to carry out VLBI

  10. Accurate 3D Mapping Algorithm for Flexible Antennas

    Directory of Open Access Journals (Sweden)

    Saed Asaly

    2018-01-01

    Full Text Available This work addresses the problem of performing an accurate 3D mapping of a flexible antenna surface. Consider a high-gain satellite flexible antenna; even a submillimeter change in the antenna surface may lead to a considerable loss in the antenna gain. Using a robotic subreflector, such changes can be compensated for. Yet, in order to perform such tuning, an accurate 3D mapping of the main antenna is required. This paper presents a general method for performing an accurate 3D mapping of marked surfaces such as satellite dish antennas. Motivated by the novel technology for nanosatellites with flexible high-gain antennas, we propose a new accurate mapping framework which requires a small-sized monocamera and known patterns on the antenna surface. The experimental result shows that the presented mapping method can detect changes up to 0.1-millimeter accuracy, while the camera is located 1 meter away from the dish, allowing an RF antenna optimization for Ka and Ku frequencies. Such optimization process can improve the gain of the flexible antennas and allow an adaptive beam shaping. The presented method is currently being implemented on a nanosatellite which is scheduled to be launched at the end of 2018.

  11. Waveform Analysis of UWB GPR Antennas

    Directory of Open Access Journals (Sweden)

    Julia Armesto

    2009-03-01

    Full Text Available Ground Penetrating Radar (GPR systems fall into the category of ultra-wideband (UWB devices. Most GPR equipment covers a frequency range between an octave and a decade by using short-time pulses. Each signal recorded by a GPR gathers a temporal log of attenuated and distorted versions of these pulses (due to the effect of the propagation medium plus possible electromagnetic interferences and noise. In order to make a good interpretation of this data and extract the most possible information during processing, a deep knowledge of the wavelet emitted by the antennas is essential. Moreover, some advanced processing techniques require specific knowledge of this signal to obtain satisfactory results. In this work, we carried out a series of tests in order to determine the source wavelet emitted by a ground-coupled antenna with a 500 MHz central frequency.

  12. Simulation of photoconductive antennas for terahertz radiation

    Directory of Open Access Journals (Sweden)

    Carlos Criollo

    2015-01-01

    Full Text Available Simulation of terahertz (THz emission based on PC antennas imposes a challenge to couple the semiconductor carrier phenomena, optical transport and the THz energy transport. In this paper a Multi-physics simulation for coupling these phenomena using COMSOL Multi-physics 4.3b is introduced. The main parameters of THz photoconductive (PC antenna as THz emitter have been reviewed and discussed. The results indicate the role of each parameter in the resulting photocurrent waveform and THz frequency: The radiated THz photocurrent waveform is determined by the photoconductive gap (the separation between the metallic electrodes, the incident laser illumination and the DC excitation voltage; while the THz frequency depends on the dipole length. The optimization of these parameters could enhance the emission. The simulations extend the advance of compact and cost-effective THz emitters.

  13. Ferrite LTCC based phased array antennas

    KAUST Repository

    Ghaffar, Farhan A.

    2016-11-02

    Two phased array antennas realized in multilayer ferrite LTCC technology are presented in this paper. The use of embedded bias windings in these designs allows the negation of external magnets which are conventionally employed with bulk ferrite medium. This reduces the required magnetostatic field strength by 90% as compared to the traditional designs. The phase shifters are implemented using the SIW technology. One of the designs is operated in the half mode waveguide topology while the other design is based on standard full mode waveguide operation. The two phase shifter designs are integrated with two element patch antenna array and slotted SIW array respectively. The array designs demonstrate a beam steering of 30° and ±19° respectively for a current excitation of 200 mA. The designs, due to their small factor can be easily integrated in modern communication systems which is not possible in the case of bulk ferrite based designs.

  14. Beating HF waves to generate VLF waves in the ionosphere

    Science.gov (United States)

    Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

    2012-03-01

    Beat-wave generation of very low frequency (VLF) waves by two HF heaters in the ionosphere is formulated theoretically and demonstrated experimentally. The heater-induced differential thermal pressure force and ponderomotive force, which dominate separately in the D and F regions of the ionosphere, drive an electron current for the VLF emission. A comparison, applying appropriate ionospheric parameters shows that the ponderomotive force dominates in beat-wave generation of VLF waves. Three experiments, one in the nighttime in the absence of D and E layers and two in the daytime in the presence of D and E layers, were performed. X mode HF heaters of slightly different frequencies were transmitted at CW full power. VLF waves at 10 frequencies ranging from 3.5 to 21.5 kHz were generated. The frequency dependencies of the daytime and nighttime radiation intensities are quite similar, but the nighttime radiation is much stronger than the daytime one at the same radiation frequency. The intensity ratio is as large as 9 dB at 11.5 kHz. An experiment directly comparing VLF waves generated by the beat-wave approach and by the amplitude modulation (AM) approach was also conducted. The results rule out the likely contribution of the AM mechanism acting on the electrojet and indicate that beat-wave in the VLF range prefers to be generated in the F region of the ionosphere through the ponderomotive nonlinearity, consistent with the theory. In the nighttime experiment, the ionosphere was underdense to the HF heaters, suggesting a likely setting for effective beat-wave generation of VLF waves by the HF heaters.

  15. Modelling of Phase Equlibria in the Hf-V System\

    Czech Academy of Sciences Publication Activity Database

    Vřešťál, Jan; Pavlů, Jana; Wdowik, U. D.; Šob, Mojmír

    2017-01-01

    Roč. 53, č. 3 (2017), s. 239-247 ISSN 1450-5339 R&D Projects: GA ČR GA14-15576S; GA MŠk(CZ) LQ1601 Institutional support: RVO:68081723 Keywords : Laves phases * Hf-V system * Ab initio calculations * Phase diagram * Zero Kelvin * CALPHAD method Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.804, year: 2016

  16. Ionizing wave via high-power HF acceleration

    OpenAIRE

    Mishin, Evgeny; Pedersen, Todd

    2010-01-01

    Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

  17. Clinical trials update from the Heart Failure Society of America Meeting 2009: FAST, IMPROVE-HF, COACH galectin-3 substudy, HF-ACTION nuclear substudy, DAD-HF, and MARVEL-1.

    Science.gov (United States)

    Lainscak, Mitja; Coletta, Alison P; Sherwi, Nasser; Cleland, John G F

    2010-02-01

    This article presents findings and a commentary on late-breaking trials presented during the meeting of the Heart Failure Society of America in September 2009. Unpublished reports should be considered as preliminary, since analyses may change in the final publication. The FAST trial showed somewhat better performance of intrathoracic impedance for prediction of deterioration in patients with heart failure (HF) when compared with daily weighing. The IMPROVE-HF study reported the benefits of education on the management of patients with systolic HF. Galectin-3 appeared a useful method for improving risk stratification of patients with chronic HF in a substudy of the COACH trial. A nuclear substudy of the HF-ACTION trial failed to demonstrate that resting myocardial perfusion imaging, a measure of myocardial scar and viability, was clinically useful. A small randomized controlled trial (DAD-HF) suggested that the use of low-dose dopamine in patients with acutely decompensated HF was associated with less deterioration in renal function and less hypokalaemia. The MARVEL-1 trial raises further concerns about the safety of myoblast transplantation in ischaemic HF.

  18. Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y-(HF) n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator.

    Science.gov (United States)

    Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

    2017-01-01

    Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y - produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y - (HF) n (Y=F, O 2 ), where larger clusters with n ≥4 were not detected. The mechanisms for the formation of the HF, F - (HF) n , and O 2 - (HF) n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F - (HF) n ( n =1-3), the energies for the loss of HF from F - (HF) 3 , F - (HF) 2 , and F - (HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy ( E CM ). These E CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O 2 (HF) n ] - ( n =1-4) was discussed on the basis of the bond lengths of O 2 H-F - (HF) n and O 2 - H-F(HF) n obtained by ab initio calculations. The calculations indicated that [O 2 (HF) 4 ] - separated into O 2 H and F - (HF) 3 .

  19. Detection of gravitational waves with resonant antennas

    International Nuclear Information System (INIS)

    Ronga, Francesco

    2006-01-01

    The status of the 4 operating cylindrical gravitational waves resonant antenna detectors is summarized. A short review is given of the experimental results and of the next generation projects. Resonant detectors are now sensitive to the strongest potential sources of gravitational waves in our galaxy and in the local group. Recently interferometric detectors have achieved very good perfomances, but resonant detectors are still competitive particularly for what concern the very good live-time

  20. Buoyant Helical Twin-Axial Wire Antenna

    Science.gov (United States)

    2016-11-15

    February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300169 1 of 9 BUOYANT HELICAL TWIN-AXIAL WIRE ANTENNA CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0001] This application is a divisional...application and claims the benefit of the filing date of United States Patent Application No. 14/280,889; filed on May 19, 2014; and entitled “Twin-Axial