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1

Electrically Small Antenna Studies.  

National Technical Information Service (NTIS)

This report summarizes the work on U. S. Army Research Office Grant No. DAAG29-76-C-0067 from 15 October 1975 to 14 October 1978. Three areas related to small antennas were investigated: wires in the presence of dielectrical ferrites, closely spaced thin ...

E. H. Newman C. H. Walter

1979-01-01

2

Efficient Radiation from an Electrically Small Antenna.  

National Technical Information Service (NTIS)

Applying the analytic technique, two antenna designs were found for which the radiation Q was below the limit determined by Chu for electrically small antennas. The simplest design is a turnstile antenna comprised of two perpendicularly oriented collocate...

C. A. Grimes

2000-01-01

3

A tunable spherical cap microfluidic electrically small antenna.  

PubMed

A highly efficient microfluidic 3D electrically small antenna is created using a simple fabrication technique. It is easy to construct simply by pneumatically inflating a planar microfluidic antenna into a spherical cap. It has premium performance around its hemispherical shape, combining a wide working band with high efficiency. PMID:23606457

Jobs, Magnus; Hjort, Klas; Rydberg, Anders; Wu, Zhigang

2013-04-18

4

Non-Foster Impedance Matching of Electrically-Small Antennas  

Microsoft Academic Search

Electrically-small antennas present high-Q impedances characterized by large reactances and small radiation resistances. For such antennas, the effectiveness of passive matching is severely limited by gain-bandwidth theory, which predicts narrow bandwidths and\\/or poor gain. With receivers, the inability to resolve this impedance mismatch results in poor signal-to-noise (S\\/N) ratio, as compared to using a full-size antenna. With transmitters, the consequence

Stephen E. Sussman-Fort; Ronald M. Rudish

2009-01-01

5

Non-Foster impedance matching of electrically small antennas  

Microsoft Academic Search

When the size of an antenna is electrically small, the antenna is neither efficient nor a good radiator because most of the input power is stored in the reactive near-field region and little power is radiated in the far-field region. As demonstrated in [1][2], the radiation quality factor of small antennas is definitely high. In other words, the input impedance

Keum-Su Song; Roberto G. Rojas

2010-01-01

6

Electrically small antenna elements using negative permittivity resonators  

Microsoft Academic Search

We show how resonators composed of negative permittivity materials can form the basis of effective small antenna elements. A quasi-static analysis of the resonant properties of a sub-wavelength negative permittivity sphere predicts that such a resonator will have a Q-factor that is only 1.5 times the Chu limit, matching the performance of other known electrically small spherical antenna designs, such

Howard R. Stuart; Alex Pidwerbetsky

2006-01-01

7

Fabrication of a 3D electrically small antenna using holographic photolithography  

NASA Astrophysics Data System (ADS)

We describe the novel fabrication of a 3D electrical small antenna and its subsequent characterization. The patterning of meander lines conformed onto a hemispherical substrate is achieved by 3D holographic photolithography, which uses time-division multiplexing of a series of iteratively optimized computer-generated holograms. The meander lines have a line width of 100 µm and line separation of 400 µm, with a line pitch of 500 µm and a total meander length of 145 mm. The working frequency is found to be 2.06 GHz, with an efficiency of 46%. This work demonstrates a new method for the fabrication of 3D conformal antennas.

Toriz-Garcia, J. J.; Cowling, J. J.; Williams, G. L.; Bai, Q.; Seed, N. L.; Tennant, A.; McWilliam, R.; Purvis, A.; Soulard, F. B.; Ivey, P. A.

2013-05-01

8

Application of double negative materials to increase the power radiated by electrically small antennas  

Microsoft Academic Search

The effect of surrounding an electrically small dipole antenna with a shell of double negative (DNG) material (?r<0 and ?r<0) has been investigated both analytically and numerically. The problem of an infinitesimal electric dipole embedded in a homogeneous DNG medium is treated; its analytical solution shows that this electrically small antenna acts inductively rather than capacitively as it would in

Richard W. Ziolkowski; Allison D. Kipple

2003-01-01

9

Low-Q, Electrically Small, Efficient Near-Field Resonant Parasitic Antennas  

Microsoft Academic Search

Metamaterial-inspired electrically small Z, stub and canopy antennas are reported. They are near-field, resonant parasitic designs. Different Z and stub antenna configurations and the effect on their Q values are studied. Their behavior led to the canopy antenna design. At the size of ka ~ 0.046, the canopy antenna is an electric-based antenna with high overall efficiency (over 90%) and

Peng Jin; Richard W. Ziolkowski

2009-01-01

10

Electrically small wire monopole antenna with Non-Foster impedance element  

Microsoft Academic Search

Electrically small antennas have excessively high radiation quality factors and low radiation resistances. This also implies that these type of antennas are narrow band. Hence it is necessary to add appropriate matching networks between the generator and the antenna. With conventional passive matching networks it is difficult to match over wide frequency bands due to the limitation of the Gain-Bandwidth

Keum-Su Song; Roberto G. Rojas

2010-01-01

11

A Hybrid Optimization Method to Analyze Metamaterial-Based Electrically Small Antennas  

Microsoft Academic Search

A model of an idealized radiating system composed of an electrically small electric dipole antenna enclosed in an electrically small multilayered metamaterial shell system is developed analytically. The far-field radiation characteristics of this system are optimized using a GA-MATLAB based hybrid optimization model. The optimized-analytical model is specifically applied to a spherical glass shell filled with a \\

Aycan Erentok; Richard W. Ziolkowski

2007-01-01

12

Analysis and optimization of an electrically small receiving antenna  

NASA Astrophysics Data System (ADS)

A theoretical and experimental study of an optimum receiving antenna configuration that fits within certain allocated space requirements is presented. This optimum monopole antenna configuration is applicable for LORAN-C reception. The antenna analysis is based on a quasi-static numerical study of a conducting body of revolution above a perfectly conducting ground plane. A general numerical algorithm is developed to determine the input impedance and the effective height of the antenna. In addition, the amplifier noise and its role in the choice of the optimum antenna are examined. Results are presented for cylindrical and truncated conical structures both with and without a top load.

Casey, John P.; Bansal, Rajeev

1991-08-01

13

Thin magnetic conductor substrate for placement-immune, electrically-small antennas.  

SciTech Connect

An antenna is considered to be placement-immune when the antenna operates effectively regardless of where it is placed. By building antennas on magnetic conductor materials, the radiated fields will be positively reinforced in the desired radiation direction instead of being negatively affected by the environment. Although this idea has been discussed thoroughly in theoretical research, the difficulty in building thin magnetic conductor materials necessary for in-phase field reflections prevents this technology from becoming more widespread. This project's purpose is to build and measure an electrically-small antenna on a new type of non-metallic, thin magnetic conductor. This problem has not been previously addressed because non-metallic, thin magnetic conductor materials have not yet been discovered. This work proposed the creation of an artificial magnetic conductor (AMC) with in-phase field reflections without using internal electric conductors, the placement of an electrically-small antenna on this magnetic conductor, and the development of a transmit-receive system that utilizes the substrate and electrically-small antenna. By not using internal electric conductors to create the AMC, the substrate thickness can be minimized. The electrically-small antenna will demonstrate the substrate's ability to make an antenna placement immune, and the transmit-receive system combines both the antenna and the substrate while adding a third layer of system complexity to demonstrate the complete idea.

Eubanks, Travis Wayne; McDonald, Jacob J.; Loui, Hung

2011-09-01

14

A reconfigurable aperture antenna based on switched links between electrically small metallic patches  

Microsoft Academic Search

A reconfigurable aperture (RECAP) antenna is described in which a planar array of electrically small, metallic patches are interconnected by switches. The antenna can be reconfigured to meet different performance goals by changing the switches that are open and closed. The switch configuration for a particular goal is determined using an optimizer, such as the genetic algorithm. First, the basic

Lon N. Pringle; Paul H. Harms; Stephen P. Blalock; Gregory N. Kiesel; Eric J. Kuster; Paul G. Friederich; Ronald J. Prado; John M. Morris; Glenn S. Smith

2004-01-01

15

Electrically small rod antennas for radio systems of space and aeronautical engineering  

Microsoft Academic Search

Theresults of decreasing the dimensions of wire antennas to the sizes of smaller resonant ones are considered, which leads\\u000a to complete mismatch of antennas’ inputs with feeders and to decreased effectiveness. Methods of optimizing and increasing\\u000a the effectiveness of these electrically small antennas and improving their input characteristics by inserting inductive and\\u000a capacitive elements at specific points in the breaks

V. V. Ovsyanikov

2010-01-01

16

Quality factor of an electrically small antenna radiating close to a conducting plane  

Microsoft Academic Search

Expressions are derived for the smallest achievable radiation quality factor (Q) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. The contribution of non-propagating energy

J. C.-E. Sten; A. Hujanen; P. K. Koivisto

2001-01-01

17

Non-Foster element, bandwidth enhanced, metamaterial-inspired electrically small antennas  

Microsoft Academic Search

Broad bandwidth metamaterial-inspired antennas have been designed and characterized numerically. Rather than introducing an external matching network that requires both resistance and reactance matching, our systems rely on internal non-Foster elements that are designed to vary the performance of their near-field resonant parasitic (NFRP) elements. Hence, by augmenting their narrow bandwidth counter-parts with internal non-Foster elements, the resulting electrically small

Richard W. Ziolkowski; Ning Zhu

2012-01-01

18

Electrically-small inductively-loaded low-profile dual sector antennas in random arrays for surface exploration and mapping  

Microsoft Academic Search

An electrically small inductively loaded dual sector antenna is investigated by varying the geometrical relationships between individual antenna parameters. Bandwidth is increased by closely spacing the resonant frequencies of each stacked sector. Inductive copper strips across the antenna aperture are adjusted to shape each sector's resonant frequency response. Rigorous simulation of these geometrical relationships leads to a highly functional design,

N. C. Soldner; P. E. Mayes; J. T. Bernhard

2005-01-01

19

Broadband, Efficient, Electrically Small Metamaterial-Inspired Antennas Facilitated by Active Near-Field Resonant Parasitic Elements  

Microsoft Academic Search

The possibility of using an active internal matching element in several types of metamaterial-inspired, electrically small antennas (ESAs) to overcome their inherent narrow bandwidths is demonstrated. Beginning with the Z antenna, which is frequency tunable through its internal lumped element inductor, a circuit model is developed to determine an internal matching network, i.e., a frequency dependent inductor, which leads to

Peng Jin; Richard W. Ziolkowski

2010-01-01

20

Conformal Phased Array Antenna Pattern Corrector.  

National Technical Information Service (NTIS)

The present invention relates to radar antenna systems and particularly to a pattern corrector for a conformal phased array monopulse antenna system. In certain monopulse radar applications, such as aboard aircraft, it becomes advantageous to mount a phas...

J. D. Antonucci

1984-01-01

21

Antenna element design for a conformal antenna array demonstrator  

Microsoft Academic Search

Conformal and structurally integrated antennas will play an increasing role in future airborne applications in various fields of interest such as Communication, Navigation, Electronic Warfare or RADAR. However, these antennas are subject to static deformations and vibrations caused by aerodynamic loads which significantly diminish the antennas performance. These effects are investigated in the scope of the interdisciplinary NATO Research Task

Peter Knott; Claudius Locker; Stephan Algermissen

2011-01-01

22

Temperature control of radar cross-section using electrically small high Tc superconducting antenna elements for stealth applications  

NASA Astrophysics Data System (ADS)

A technique to reduce unwanted scattering by antennas which exploits the inefficiency of high-temperature superconductors above Tc is demonstrated. Electrically small dipole and loop antennas made of superconductors are modeled above and below Tc to predict their scattering efficiencies, and it is shown that a significant transition in radar cross-section occurs which justifies the use of superconductors over copper in stealth applications.

Cook, G. G.; Khamas, S. K.

1993-08-01

23

Artificial composite materials consisting of nonlinearly loaded electrically small antennas: operational-amplifier-based circuits with applications to smart skins  

Microsoft Academic Search

Several new artificial nonlinear composite materials are introduced in this paper. They consist of electric molecules constructed with nonlinearly loaded electrically small dipole antennas. Their behaviors are studied with an augmented finite-difference time-domain (FDTD) simulator. The loads are based upon the use of multiple diodes and ideal operational amplifiers. The resulting composite materials are shown to have nonlinear electromagnetic properties

Fabrice Auzanneau; Richard W. Ziolkowski

1999-01-01

24

Introduction of internal matching circuit to increase the bandwidth of a metamaterial-inspired efficient electrically small antenna  

Microsoft Academic Search

The performance characteristics of a simplified electric, lumped-element based, meta-material -inspired, efficient, electrically small antenna have been determined numerically for a fixed reactive element value over a band of frequencies. These characteristics were used to define an internal matching network (in contrast to the usual non-Foster external matching networks) which would provide the appropriate reactance at the appropriate frequency that

Richard W. Ziolkowski; Peng Jin

2008-01-01

25

The Study and Implementation of Electrically Small Printed Antennas for an Integrated Transceiver Design  

SciTech Connect

This work focuses on the design and evaluation of the inverted-F, meandering-monopole, and loop antenna geometries. These printed antennas are studied with the goal of identifying which is suitable for use in a miniaturized transceiver design and which has the ability to provide superior performance using minimal Printed Circuit Board (PCB) space. As a result, the main objective is to characterize tradeoffs and identify which antenna provides the best compromise among volume, bandwidth and efficiency. For experimentation purposes, three types of meandering-monopole antenna are examined resulting in five total antennas for the study. The performance of each antenna under study is evaluated based upon return loss, operational bandwidth, and radiation pattern characteristics. For our purposes, return loss is measured using the S11-port reflection coefficient which helps to characterize how well the small antenna is able to be efficiently fed. Operational bandwidth is measured as the frequency range over which the antenna maintains 2:1 Voltage Standing Wave Ratio (VSWR) or equivalently has 10-dB return loss. Ansoft High Frequency Structure Simulator (HFSS) is used to simulate expected resonant frequency, bandwidth, VSWR, and radiation pattern characteristics. Ansoft HFSS simulation is used to provide a good starting point for antenna design before actual prototype are built using an LPKF automated router. Simulated results are compared with actual measurements to highlight any differences and help demonstrate the effects of antenna miniaturization. Radiation characteristics are measured illustrating how each antenna is affected by the influence of a non-ideal ground plane. The antenna with outstanding performance is further evaluated to determine its maximum range of communication. Each designs range performance is evaluated using a pair of transceivers to demonstrate round-trip communication. This research is intended to provide a knowledge base which will help decrease the number of design iterations needed for future implementation of products requiring integration of small printed antennas. In the past, several design iterations have been needed to fine tune antenna dimensions and achieve acceptable levels of performance. This process consumes a large amount of time and material resources leading to costly development of transceiver designs. Typically, this occurs because matching components and antenna geometries are almost never correct on the first design. This work hopes to determine the limitations associated with antenna miniaturization and provide well known antenna examples that can be easily used in future work.

Speer, Pete

2009-04-15

26

Design and measurements of an electrically small, broad bandwidth, non-Foster circuit-augmented protractor antenna  

NASA Astrophysics Data System (ADS)

A broad bandwidth, electrically small, metamaterial-inspired protractor antenna was designed, fabricated and tested around 300 MHz. Its broad bandwidth property was achieved by augmenting the protractor-shaped near-field resonant parasitic (NFRP) element with a non-Foster circuit. The resulting active NFRP element provided the means to surpass the fundamental passive limits. The measurement results for this non-Foster protractor antenna showed more than a 10 times increase of the 10 dB fractional bandwidth (FBW10dB) of the original passive version. The corresponding half-power bandwidth (BW3dB) was more than 8.24 times the passive upper bound.

Zhu, Ning; Ziolkowski, Richard W.

2012-07-01

27

Conformal strip excitation of dielectric resonator antenna  

Microsoft Academic Search

A new excitation scheme that employs a conducting conformal strip is proposed for dielectric resonator antenna (DRA) excitation. The new excitation scheme is successfully demonstrated by using a hemispherical DRA whose exact Green function is found using the mode-matching method. The moment method is used to solve the unknown strip current from which the input impedance is obtained. Novel recurrence

Kwok Wa Leung

2000-01-01

28

Non-Foster vs. active matching of an electrically-small receive antenna  

Microsoft Academic Search

We consider herein a comparison between non-Foster matching and classical active matching, in which a transistor buffer stage is placed at the antenna terminals. We found the active-antenna approach to be quite effective, with a performance actually surpassing that of an earlier non-Foster circuit. Further work has led to the development of an enhanced NIC that restores the preeminence of

S. E. Sussman-Fort

2010-01-01

29

Efficiency of Electrically Small Dipole Antennas Loaded With Left-Handed Transmission Lines  

Microsoft Academic Search

A study of the efficiency of small dipole antennas loaded with a left-handed transmission line is described. The antenna is composed of a ladder network periodic structure of a number of unit cells. Left-handed performance can be obtained in straight or meandered capacitive-inductive (CL) lumped loading. Its performance is compared to a right-handed dipole with inductive (L) lumped loading. Differently

Qing Liu; Peter S. Hall; Alejandro L. Borja

2009-01-01

30

A re-examination of the fundamental limits on the radiation Q of electrically small antennas  

Microsoft Academic Search

An exact method, which is more straightforward than those previously published, is derived for the calculation of the minimum radiation Q of a general antenna. This expression agrees with the previously published and widely cited approximate expression in the extreme lower limit of electrical size. However, for the upper end of the range of electrical size which is considered electrically

James S. McLean

1996-01-01

31

Design and development of conformal smart spiral antenna  

Microsoft Academic Search

Recently there has been considerable interest toward designing `smart skin spiral antenna' for aircraft. These antennas when used for EW systems generally require multioctave frequency bandwidths to receive and\\/or transmit signals over a wide frequency range. In this paper a smart skin conformal antenna is designed which consists of a thin tunable dielectric sheet, interdigital transducer and notch filter and

Vijay K. Varadan; Vasundara V. Varadan

1996-01-01

32

Input impedance analysis of spherical conformal antennas by means of conformal transformation  

Microsoft Academic Search

A method of the conformal transformation, combined with an analytical model, for calculating the input impedance of spherical conformal antennas is developed in this paper. It is demonstrated to maintain the simplicity and clear physical explanation of the analytical model for deciding the characteristics of antennas, while the result showed it matches the MoM results well. The computational efficiency is

Xu Xiaojing; Zhu Qi; Li Yan

2004-01-01

33

A conformal Taguchi optimized E-patch antenna  

NASA Astrophysics Data System (ADS)

The performance of a cavity-backed E-patch antenna placed conformal to a cylindrical conducting surface is explored numerically using the finite element boundary integral (FE-BI) method. From using rigorous full-wave simulations based on the finite element method, the effects of curvature are assessed for such antenna characteristics as bandwidth and impedance. The necessary changes to the patch geometry to maintain an acceptable impedance match and a desired bandwidth for rectangular cavity-backed E-patch antennas are determined. Cylindrically conformal cavity-backed E-patch antennas are simulated and perform well with many different cylinder radii. A experimental cylindrical conformal cavity-backed E-patch antenna was built to verify simulations and preformed well at the L1 and L2 frequencies. Radiation patterns of both experimental and simulated cylindrically conformal cavity-back E-patch antennas are analyzed and perform well. Taguchi's method of optimization is used to optimize |S 11| of rectangular cavitybacked E-patch antennas. Using Matlab and rigorous full-wave simulations based on the finite element method in combination, the effects of having different fitness functions, level differences, and input parameters in Taguchi's method of optimization are explored and determined.

Gardner, C. M.

34

Polymer-Carbon Nanotube Sheets for Conformal Load Bearing Antennas  

Microsoft Academic Search

We propose a conductive carbon nanotube (CNT) sheet to realize conformal antennas on polymer substrates. Polymer-ceramic composites (rubber-like structures) have good RF (high dielectric constant and low loss tangent) and desirable mechanical properties (conformal, flexible and lightweight). However, there is a challenge in printing metallization circuits on polymer substrates due to their hydrophobic nature. Also, they are associated with low

Yijun Zhou; Yakup Bayram; Feng Du; Liming Dai; John L. Volakis

2010-01-01

35

OMNIDIRECTIONAL CONFORMAL MICROSTRIP PATCH ANTENNAS WITH PASSIVE PERIODIC SUPERSTRATES  

Microsoft Academic Search

Conformal periodic metallic arrays printed on thin dielectric substrate behave as Partially Reflecting Surfaces (PRS) when placed above a cylindrical metallic ground. This configuration provides some advantages: i) a low number of array elements to achieve high directivity in the elevation plane, ii) omni-directional radiation patterns in the azimuth plane due to the conformal nature of the antenna, iii) a

G. K. Palikaras; A. P. Feresidis; J. C. Vardaxoglou

36

Design methodology for Sievenpiper high-impedance surfaces: an artificial magnetic conductor for positive gain electrically small antennas  

Microsoft Academic Search

The Sievenpiper high-impedance surface is a periodic structure characterized by a substrate filled with an array of vertical vias, capped by a capacitive frequency selective surface (FSS). It functions as the ideal antenna groundplane for wireless applications because it simultaneously enhances the gain of the antenna as it suppresses the surface waves associated with it (thus reducing the undesired back-lobe

Sergio Clavijo; Rodolfo E. Díaz; William E. McKinzie

2003-01-01

37

Simulation and analysis of a hemispherical conformal sinuous antenna with four arms  

Microsoft Academic Search

In this paper, a hemispherical conformal sinuous antenna with four arms is discussed. The radiation performances of a specific hemispherical conformal sinuous antenna model are simulated and analyzed. The structure and parameters of the discussed antenna are introduced and the simulation results indicate that the discussed antenna has still the ultra wide band (UWB) characteristics of impedance and wide beam

Song Lizhong; Cong Guojin; Hong Huanfeng

2010-01-01

38

High Data Rate Link from DIVA Using a Conformal Antenna  

NASA Astrophysics Data System (ADS)

Like some other small spinning scientific satellites, DIVA has a fixed position of the spinning axis with respect to sun. Due to this alignment, the earth can appear in any angular position relative to the satellite, which causes the need for an antenna with full spherical coverage to maintain a permanent link to the control facilities on earth. Up to now this coverage usually was achieved by the use of ordinary TT&C-antennas, as they are utilized on communication satellites for telemetry, tracing and command. In this control application there is no need for high-data-rate communication, so this antenna neither offers high bandwidth nor high gain. Especially the low gain of this antenna type results in a bad signal-to-noise ratio (SNR) at the receiving antenna on the earth. As a consequence the low SNR limits the data rate to small values. In scientific missions with a high amount of data needed to be transferred to the earth, the use of these antennas results in a bottle neck in the data link and lowers the efficiency of the scientific mission itself. An increase in SNR at the receiving antenna needs an increase in signal strength because the noise figure of commercially used receiving antennas on the earth is already extremely low and cannot be lowered further without major technical effort. Hence the gain of the transmitting antenna on the satellite has to be increased. In this contribution a broadband conformal antenna concept is presented which yields an average gain of 7.6 dBi over the full sphere for the antenna on the satellite. The antenna consists of 26 elements which are located at different positions on the surface of the satellite. By using the knowledge of the earth's angular position from the satellite's navigation system, the element pointing best towards the earth is used for the link. Technically this problem is solved by using a low-loss switching matrix. Slot spirals are used as single elements. The element consists of an etched slot spiral on an RT/duroid 6002 substrate. A honeycomb structure and a carrier complete the simple mechanical setup of the single element. Using this new antenna there appears to be no limitation in the bandwidth of the data link due to the transmitting antenna, because the bandwidth of the used slot spiral can easily be one octave. Besides the large bandwidth, the pure circular polarisation is a major advantage of the spiral antenna. A usable data rate of 1.2 Mbit/s having a BER of 10^{-5} can be achieved using this switched conformal array antenna and an RF-bandwidth of 2 MHz in S-band.

Loeffler, D.; Wiesbeck, W.; Wiesler, A.; Bastian, U.; Roeser, S.; Mandel, H.; Seifert, W.; Wagner, S.

39

Closely Coupled Multi-Mode Radiators: A New Concept for Improving the Performance of Electrically Small Antennas.  

National Technical Information Service (NTIS)

This document is the first interim research performance report of the Young Investigator Program (YIP) project funded by the Office of Naval Research. In this reporting period, we focused on examining the performance of the dual-mode conformal, ultra-broa...

N. Behdad

2012-01-01

40

Array Manifold Modeling for Arbitrary 3D Conformal Array Antenna  

Microsoft Academic Search

Conformal array antennas (CAA) [L. Josefsson and P. Persson, 2006] will find their potential and promising applications in a variety of fields ranging from space-borne, airborne, ship-borne, and missile-borne radar, space vehicles and wireless communications to sonar, etc. Their benefits include reduction of aerodynamic drag, wide angle coverage, space saving, potential increase in available aperture, reduction of radar cross-section (RCS)

Wang Bu-hong; Guo Ying

2008-01-01

41

Constrained Least-Squares Optimization in Conformal Array Antenna Synthesis  

Microsoft Academic Search

The least mean square error of the constrained least-squares optimization method is studied. The phases of non-zero goal values and the phases of non-zero constraint values can be selected by a fast iteration for optimum fit to the goal function amplitude. This kind of modified least-squares optimization method opens up a fast and robust synthesis method for large conformal antenna

Leo I. Vaskelainen

2007-01-01

42

Integration of conformal GPS and VHF\\/UHF communication antennas for small UAV applications  

Microsoft Academic Search

The integration of GPS and VHF\\/UHF antennas occupying the same physical volume conformal to the tail of a small UAV is presented in this paper. Traditionally each antenna requires its own volume, thus limiting the number of antennas, reducing the UAV functionality. The GPS antenna covers both the L1 and L2 bands while the VHF\\/UHF antenna can operate from 30

Brandan T. Strojny; Roberto G. Rojas

2009-01-01

43

Design and development of smart skin conformal antenna with MEMS structural sensors and actuators  

Microsoft Academic Search

Recently there has been considerable interest toward designing and developing `smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radar, conformal microstrip or spiral antennas for electromagnetic applications. These embedded antennas will given rise to very low radar cross section or can be completely `hidden' to tracking radar. In addition, they can be used

Vijay K. Varadan; Vasundara V. Varadan

1997-01-01

44

Ultra-wideband omnidirectional conformable low-profile mode-0 spiral-mode microstrip (SMM) antenna  

Microsoft Academic Search

An ultra-wideband low-profile platform-conformable omnidirectional antenna based on the mode-0 SMM antenna has been developed. Its 10:1 gain bandwidth is slightly larger than that of the well-established conical monopole, yet its height is less than half that of the monopole. Compared with other well-known low-profile omnidirectional antennas with a gain bandwidth over 2:1, its gain bandwidth of 10:1 is much

Johnson J. H. Wang; Chris J. Stevens; D. J. Triplett

2005-01-01

45

Conformal WLAN\\/WiMAX antenna on rigid-flex liquid crystalline polymer based substrate  

Microsoft Academic Search

Recent developments in liquid crystalline polymer (LCP)-based procesing technology have shown that highly-integrated, fully-packaged RF front-end modules with high performance can be designed by using the system-onpackage (SOP) approach. However, direct integration of a large antenna element to a small module package still remains an isue. This paper presents a novel conformal antenna structure which results in a compact integration

Nevin Altunyurt; Madhavan Swaminathan; Ralf Rieske; Venkatesh Sundaram

2009-01-01

46

Phase-compensated metasurface for a conformal microwave antenna  

NASA Astrophysics Data System (ADS)

The in-phase radiation from a conformal metamaterial surface is numerically and experimentally reported. The LC-resonant metasurface is composed of a simultaneously capacitive and an inductive grid constituted by copper strips printed on both sides of a dielectric board. The metasurface is designed to fit a curved surface by modifying its local phase. The latter phase-compensated metasurface is used as a reflector in a conformal Fabry-Pérot resonant cavity designed to operate at microwave frequencies. Far-field measurements performed on a fabricated prototype allow showing the good performances of such a phase-compensated metasurface in restoring in-phase emissions from the conformal surface and producing a directive emission in the desired direction.

Germain, Dylan; Seetharamdoo, Divitha; Nawaz Burokur, Shah; de Lustrac, André

2013-09-01

47

Conformal load-bearing antenna structures (CLAS): initiative for multiple military and commercial applications  

NASA Astrophysics Data System (ADS)

The Structures Division of the Air Force's Wright Laboratory is sponsoring the development and demonstration of a new high pay-off technology termed CLAS--Conformal Load Bearing Antenna Structures. Northrop Grumman Corporation and TRW/ASD are developing the technology under the `Smart-Skin Structure Technology Demonstration (S3D)' program, contract, No. F33615-93-C-3200. The program goal is to design, develop, fabricate, and test a CLAS component and lay the foundation for future work where potential benefits from structurally integrated antennas may be realized. Key issues will focus but are not limited to the design, structures, and manufacturing aspects of antenna embedment into load bearing aircraft structures. Results from Phase 1 of the program have been previously reported, where initial pay-offs in reducing overall airframe acquisition and support cost, weight, signature, and drag were quantitatively and qualitatively identified. A full-sized CLAS component, featuring a broadband multi-arm spiral embedded in sandwich stiffened structure, will be fabricated and tested for static strength, durability, and damage tolerance. Basic electrical performance, (e.g., radiation patterns, gain, and impedance) will also be verified; however, extensive electrical validation will be the subject of further work. Key aspects of the work and progress to date are detailed below. Also covered are future projections of CLAS technology expansion beyond tactical aircraft into other military products highlighting ships, army vehicles, and `spin-off' commercial applications to civil aircraft and the automotive industry.

Lockyer, Allen J.; Alt, Kevin H.; Kudva, Jayanth N.; Kinslow, Robert W.; Goetz, Allen C.

1997-06-01

48

Time-Dependent Numerical Method with Boundary-Conforming Curvilinear Coordinates Applied to Wave Interactions with Prototypical Antennas  

Microsoft Academic Search

A new unstaggered finite-difference time-dependent technique to accurately model scattring from prototypical 2D antenna structures is devised. The unbounded boundary value problems defining these phenomena are redefined over bounded domains using appropriate radiation operators over finite artificial boundaries. Generalized curvilinear coordinates are generated such that physical boundaries correspond to coordinate lines. A numerical procedure to generate almost orthogonal, boundary-conforming, fine

Vianey Villamizar; Otilio Rojas

2002-01-01

49

Size reduction and radiation pattern shaping of multi-fed DCC slot antennas used in conformal microwave array hyperthermia applicators  

NASA Astrophysics Data System (ADS)

The use of conformal antenna array in the treatment of superficial diseases can significantly increase patient comfort while enhancing the local control of large treatment area with irregular shapes. Originally a regular square multi-fed slot antenna (Dual Concentric Conductor - DCC) was proposed as basic unit cell of the array. The square DCC works well when the outline of the treatment area is rectangular such as in the main chest or back area but is not suitable to outline diseases spreading along the armpit and neck area. In addition as the area of the patch increases, the overall power density decreases affecting the efficiency and thus the ability to deliver the necessary thermal dose with medium power amplifier (<50W). A large number of small efficient antennas is preferable as the disease is more accurately contoured and the lower power requirement for the amplifiers correlates with system reliability, durability, linearity and overall reduced cost. For such reason we developed a set of design rules for multi-fed slot antennas with irregular contours and we implemented a design that reduce the area while increasing the perimeter of the slot, thus increasing the antenna efficiency and the power density. The simulation performed with several commercial packages (Ansoft HFSS, Imst Empire, SemcadX and CST Microwave Studio) show that the size reducing method can be applied to several shapes and for different frequencies. The SAR measurements of several DCCs are performed using an in-house high resolution scanning system with tumor equivalent liquid phantom both at 915 MHz for superficial hyperthermia systems in US) and 433 MHz (Europe). The experimental results are compared with the expected theoretical predictions and both simulated and measured patterns of single antennas of various size and shapes are then summed in various combinations using Matlab to show possible treatment irregular contours of complex diseases. The local control is expected to significantly improve while maintaining the patient comfort.

Maccarini, Paolo F.; Arunachalam, Kavitha; Martins, Carlos D.; Stauffer, Paul R.

2009-02-01

50

Development of a conformal load-carrying smart skin antenna for military aircraft  

Microsoft Academic Search

A multifunction structurally embedded antenna panel installation concept is presented which offers a near term solution to the increasing antenna proliferation problem of high technology aircraft. The concept has evolved from the Air Force sponsored program 'Smart Skin Structures Demonstration Program', recently awarded to Northrop Grumman, and is consistent with the Forecast II smart skin initiatives of the early 1990s.

Allen J. Lockyer; Jayanth N. Kudva; Kevin H. Alt; Allan C. Goetz; Jim Tuss

1995-01-01

51

Colocated Magnetic Loop, Electric Dipole Array Antenna (Preliminary Results).  

National Technical Information Service (NTIS)

We present a detailed electromagnetic analysis of an electrically small colocated electric dipole and magnetic loop antenna array. This antenna is the simplest example of the Grimes multipole class of antenna arrays. We have determined that since the inte...

P. L. Overfelt D. R. Bowling D. J. White

1994-01-01

52

Size reduction of a folded conical helix antenna  

Microsoft Academic Search

A wire antenna that utilizes spiraling and folding has been reported by Dobbins, and Rogers (see IEEE Trans. Antennas and Propagat., Dec. 2001). We have shown that this antenna, called the folded conical helix antenna (FLEX), performs very well as an electrically small monopole antenna. Using the figure of merit proposed in this work we can quantitatively compare this antenna

R. L. Rogers; D. P. Buhl; Hosung Choo; Hao Ling

2002-01-01

53

Photonic systems for antenna control  

Microsoft Academic Search

There are many techniques for optically carrying an RF signal from an antenna element to its receiver, thus, optically isolating the antenna. However, if the antenna needs to be tuned or the matching network needs to be controlled then it is desirous to perform that function optically as well. We show that an optically-linked electrically-small loop can be tuned over

M. L. Van Blaricum; C. J. Swann

1995-01-01

54

Theory and Simulations of a Conformal Omni- Directional Subwavelength Metamaterial Leaky-Wave Antenna  

Microsoft Academic Search

The detailed theory of a single subwavelength conformal radiator that exploits the resonant properties of thin cylindrical metamaterial shells supporting leaky waves is presented. It is shown and reviewed analytically and numerically how a circularly symmetric resonant leaky mode may be supported by a properly designed subwavelength homogenous cylindrical shell of low negative permittivity. Some physical insights are provided and

Andrea Al; Filiberto Bilotti; Nader Engheta; Lucio Vegni

2007-01-01

55

The Zeaxanthin-Independent and Zeaxanthin-Dependent qE Components of Nonphotochemical Quenching Involve Common Conformational Changes within the Photosystem II Antenna in Arabidopsis1[W  

PubMed Central

The light-harvesting antenna of higher plant photosystem II (LHCII) has the intrinsic capacity to dissipate excess light energy as heat in a process termed nonphotochemical quenching (NPQ). Recent studies suggest that zeaxanthin and lutein both contribute to the rapidly relaxing component of NPQ, qE, possibly acting in the minor monomeric antenna complexes and the major trimeric LHCII, respectively. To distinguish whether zeaxanthin and lutein act independently as quenchers at separate sites, or alternatively whether zeaxanthin fulfills an allosteric role regulating lutein-mediated quenching, the kinetics of qE and the qE-related conformational changes (?A535) were compared in Arabidopsis (Arabidopsis thaliana) mutant/antisense plants with altered contents of minor antenna (kolhcb6, aslhcb4), trimeric LHCII (aslhcb2), lutein (lut2, lut2npq1, lut2npq2), and zeaxanthin (npq1, npq2). The kinetics of the two components of NPQ induction arising from zeaxanthin-independent and zeaxanthin-dependent qE were both sensitive to changes in the protein composition of the photosystem II antenna. The replacement of lutein by zeaxanthin or violaxanthin in the internal Lhcb protein-binding sites affected the kinetics and relative amplitude of each component as well as the absolute chlorophyll fluorescence lifetime. Both components of qE were characterized by a conformational change leading to nearly identical absorption changes in the Soret region that indicated the involvement of the LHCII lutein 1 domain. Based on these observations, we suggest that both components of qE arise from a common quenching mechanism based upon a conformational change within the photosystem II antenna, optimized by Lhcb subunit-subunit interactions and tuned by the synergistic effects of external and internally bound xanthophylls.

Johnson, Matthew P.; Perez-Bueno, Maria L.; Zia, Ahmad; Horton, Peter; Ruban, Alexander V.

2009-01-01

56

The zeaxanthin-independent and zeaxanthin-dependent qE components of nonphotochemical quenching involve common conformational changes within the photosystem II antenna in Arabidopsis.  

PubMed

The light-harvesting antenna of higher plant photosystem II (LHCII) has the intrinsic capacity to dissipate excess light energy as heat in a process termed nonphotochemical quenching (NPQ). Recent studies suggest that zeaxanthin and lutein both contribute to the rapidly relaxing component of NPQ, qE, possibly acting in the minor monomeric antenna complexes and the major trimeric LHCII, respectively. To distinguish whether zeaxanthin and lutein act independently as quenchers at separate sites, or alternatively whether zeaxanthin fulfills an allosteric role regulating lutein-mediated quenching, the kinetics of qE and the qE-related conformational changes (DeltaA535) were compared in Arabidopsis (Arabidopsis thaliana) mutant/antisense plants with altered contents of minor antenna (kolhcb6, aslhcb4), trimeric LHCII (aslhcb2), lutein (lut2, lut2npq1, lut2npq2), and zeaxanthin (npq1, npq2). The kinetics of the two components of NPQ induction arising from zeaxanthin-independent and zeaxanthin-dependent qE were both sensitive to changes in the protein composition of the photosystem II antenna. The replacement of lutein by zeaxanthin or violaxanthin in the internal Lhcb protein-binding sites affected the kinetics and relative amplitude of each component as well as the absolute chlorophyll fluorescence lifetime. Both components of qE were characterized by a conformational change leading to nearly identical absorption changes in the Soret region that indicated the involvement of the LHCII lutein 1 domain. Based on these observations, we suggest that both components of qE arise from a common quenching mechanism based upon a conformational change within the photosystem II antenna, optimized by Lhcb subunit-subunit interactions and tuned by the synergistic effects of external and internally bound xanthophylls. PMID:19011000

Johnson, Matthew P; Pérez-Bueno, María L; Zia, Ahmad; Horton, Peter; Ruban, Alexander V

2008-11-14

57

Development of a structurally integrated conformal load-bearing multifunction antenna: overview of the Air Force Smart Skin Structures Technology Demonstration Program  

Microsoft Academic Search

The Structures Division of the Air Force's Wright Laboratory is sponsoring the development and demonstration of a new high pay-off technology termed CLAS--Conformal Load Bearing Antenna Structures. Northrop Grumman Corporation and TRW\\/ASD are developing the technology under the `Smart-Skin Structure Technology Demonstration (S3D)' program, contract, No. F33615-93-C-3200. The program goal is to design, develop, fabricate, and test a CLAS component

Allen J. Lockyer; Kevin H. Alt; Robert W. Kinslow; Han-Pin Kan; Jayanth N. Kudva; Jim Tuss; Allan C. Goetz

1996-01-01

58

Small Wideband Antenna with non-Foster Loading Elements  

Microsoft Academic Search

The paper demonstrates a new way of overcoming the fundamental limit imposed on the fractional bandwidth of small antennas in relation to antenna volume by means of using a non-Foster (active) network. Unlike the techniques known in literature that use non-Foster matching circuits to broaden the operating bandwidth of electrically small antennas, the present approach utilizes the specific antenna structure

G. Bit-Babik; C. Di Nallo; J. Svigelj; A. Faraone

2007-01-01

59

Prototype testing and evaluation of a structurally integrated conformal antenna installation in the vertical tail of a military aircraft  

Microsoft Academic Search

Further proof-of-concept development for structurally integrating communication antennas in the vertical tail of a military aircraft at Northrop Grumman is presented. Bread board testing on a full scale dual tail aircraft mock-up of a structurally integrated multifunction tail tip antenna, in the VHF-FM, VHF-AM, and UHF-AM frequency regimes, has confirmed earlier simulation results, where it was suggested that smart skin

Allen J. Lockyer; Jayanth N. Kudva; Daniel P. Coughlin; Kevin H. Alt; Christopher A. Martin; Michael D. Durham; Allen C. Goetz

1997-01-01

60

Development of a structurally integrated conformal load-bearing multifunction antenna: overview of the Air Force Smart Skin Structures Technology Demonstration Program  

NASA Astrophysics Data System (ADS)

The Structures Division of the Air Force's Wright Laboratory is sponsoring the development and demonstration of a new high pay-off technology termed CLAS--Conformal Load Bearing Antenna Structures. Northrop Grumman Corporation and TRW/ASD are developing the technology under the `Smart-Skin Structure Technology Demonstration (S3D)' program, contract, No. F33615-93-C-3200. The program goal is to design, develop, fabricate, and test a CLAS component and lay the foundation for future work where potential benefits from structurally integrated antennas may be realized. Key issues will focus but are not limited to the design, structures, and manufacturing aspects of antenna embedment into load bearing aircraft structures. Results from Phase I of the program have been previously reported, where initial pay-offs in reducing overall airframe acquisition and support cost, weight, signature, and drag were quantitatively and qualitatively identified. A full-sized CLAS component, featuring a broadband multi-arm spiral embedded in sandwich stiffened structure, will be fabricated and tested for static strength, durability, and damage tolerance. Basic electrical performance, (e.g. radiation patterns, gain, and impedance) will also be verified; however, extensive electrical validation will be the subject of further work. Key aspects of the work and progress to date are detailed below.

Lockyer, Allen J.; Alt, Kevin H.; Kinslow, Robert W.; Kan, Han-Pin; Kudva, Jayanth N.; Tuss, Jim; Goetz, Allan C.

1996-05-01

61

A Non-Foster VHF Monopole Antenna  

Microsoft Academic Search

Non-Foster matching promises to improve the performance of electrically small antennas by tens of decibels over a decade of bandwidth, but only a few successful demonstrations have been reported in the literature. A 15-cm monopole antenna has been matched using a variable negative capacitance based on Linvill's balanced negative impedance converter. The realized gain is improved by $> $10 dB

Carson R. White; Joseph S. Colburn; Robert G. Nagele

2012-01-01

62

GA design of small wire antennas  

Microsoft Academic Search

A multiobjective genetic algorithm (GA) has been applied to the design of electrically small thin-wire antennas taking into account the resonance frequency, efficiency and Q factor of the different configurations. The performance of the resulting designs is compared to that of other prefractal antennas of similar size.

M. Fe-dez Pantoja; F. G. Ruiz; A. R. Bretones; R. G. Martin; S. G. Garcia; J. M. Gonzalez-Arbesu; J. Romeu; J. M. Rius; D. H. Werner; P. L. Werner

2004-01-01

63

Smart skin spiral antenna with chiral absorber  

Microsoft Academic Search

Recently there has been considerable interest toward designing 'smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radars, conformal microstrip antennas or spiral antennas for electromagnetic applications. These embedded antennas will give rise to very low radar cross section (RCS) or can be completely 'hidden' to tracking radar. In addition, they can be used

Vijay K. Varadan; Vasundara V. Varadan

1995-01-01

64

Reactively Steered Ring Antenna Array for Automotive Application  

Microsoft Academic Search

A novel type of smart antenna, called a reactively steered ring antenna array (RSRAA), is proposed. The antenna features a conformal configuration with three overlapping one-wavelength ring elements. Directivity can be controlled by changing the values of variable reactance circuits that are embedded in the antenna. The antenna can be mounted on the windshield of an automobile without interfering with

Shinya Sugiura; Hideo Iizuka

2007-01-01

65

Design of resonant small antenna using composite right\\/left-handed transmission line  

Microsoft Academic Search

The paper presents the design of an electrically small antenna employing a composite right\\/left-handed (CRLH) transmission line. The physical size and operating frequency of the antenna depend on the unit cell size and equivalent transmission line model parameters. Therefore, the small antenna is realized by miniaturizing the unit cell and increasing the shunt inductance and series capacitance. A four unit

Cheng-Jung Lee; K. M. K. H. Leong; T. Itoh

2005-01-01

66

Standard antennas for electromagnetic interference measurements and methods to calibrate them  

Microsoft Academic Search

This tutorial paper discusses various standard antennas for measuring radio-frequency electric and magnetic fields. A theoretical analysis of each antenna's receiving characteristics is summarized and referenced. The antennas described are an electrically short dipole, a resistively loaded short dipole and halfwave dipole, an electrically small loop, a resistively loaded loop, photonic probes, and a single-turn loop designed for simultaneous measurement

Motohisa Kanda

1994-01-01

67

A novel compact UHF wideband antenna for near field electrical characterization of Steel Fiber Reinforced Concrete  

Microsoft Academic Search

A novel, electrically small, UHF (350 MHz-750 MHz) microstrip slot antenna is presented. The antenna is designed for the characterization of steel fiber reinforced concrete (SFRC) segments. The antenna consists on a three layer structure headed by the slot ground plane, followed by the feeding microstrip in the central layer with some resistive loading for bandwidth enhancement purposes; finally on

G. Roqueta; S. Irteza; J. Romeu; L. Jofre

2009-01-01

68

Application for smart skin technologies to the development of a conformal antenna installation in the vertical tail of a military aircraft  

Microsoft Academic Search

Recent developments in smart skins technology at Northrop Grumman have paved the way toward incorporating avionics communication functions, previously provided by blade antennas, into the vertical tail of a military aircraft. Radio frequency communication link ranges can be significantly improved by structurally integrating the antenna radiating element into the tail region. Excitation of the large vertical tail surface improves radiation

Kevin H. Alt; Allen J. Lockyer; Christopher A. Martin; Jayanth N. Kudva; Allan C. Goetz

1995-01-01

69

Advanced MMW antenna system for hypervelocity interceptors  

SciTech Connect

Application of conformal surface wave antennas for RF homing systems on endo-atmospheric interceptors is considered. Conformal apertures near the base of the interceptor are employed to generate orthogonal, steerable fan beams for target aquisition and tracking with minimal incursion of the internal interceptor volume. Measured patterns demonstrate the viability of the antenna concept.

Newman, G.; Bryanos, J.; Gale, J.; Harris, M.; Shui, Ven; Monk, V.; Mullins, J. (Textron Defense Systems, Wilmington, MA (United States) U.S. Army, Missile Command, Redstone Arsenal, Huntsville, AL (United States))

1992-05-01

70

Analysis of the Efficiency Improvement of a Directly-Driven Antenna- Based AM Transmitter.  

National Technical Information Service (NTIS)

The operation of a traditional radio transmitter is limited by the frequency range over which the antenna input impedance can be conjugately matched to the power amplifier output impedance. This limitation is particularly strong when an electrically-small...

O. O. Olaode W. D. Palmer W. T. Joines

2009-01-01

71

The polarizabilities of electrically small apertures of arbitrary shape  

Microsoft Academic Search

Numerical procedures, based on a method of moments approach, are presented for computing the magnetic and electric polarizabilities of electrically small apertures of arbitrary shape. The magnetic polarizability density is determined by using pulse expansion functions defined over quadrilateral subdomains, while the electric polarizability density is obtained by using basis functions. Each of the basis functions consists of a piecewise

Ephraim Okon; R. F. Harrington

1981-01-01

72

Superconducting matching networks in monopole antennas. Final report, 1 Aug 89-31 Jul 91  

SciTech Connect

The goals of this program were to demonstrate the performance advantages of UHF Super Directive Array using a monopole antenna matching network made of high temperature superconducting (HTS) material over a monopole antenna matching network made of gold and to demonstrate the feasibility of using HTS material matching networks to feed a two element electrically small superdirective monopole array. In both cases only the matching networks were made of HTS material. The radiators were made of silver, copper, and steel. The electrically small monopole antenna and the electrically small element monopole antenna array were operated in the UHF band because the need exists for a high efficiency electrically small array operating in the UHF range as part of a multispectral seeker of an air-to-air missile. To date no antenna system consisting of electrically small conventional metal monopole radiators and HTS material matching networks has been demonstrated. An electrically small superdirective monopole array with superconducting matching networks is a candidate for use in an air-to-air missile as part of a multispectral seeker. The seeker must have a multispectral capability in order to successfully engage advanced Low Observable aircraft and missiles. The air-to-air missile guidance is initially provided by a surveillance and control aircraft.

Piatnicia, A.Y.; Talisa, S.H.; Buckley, M.J.; Gavaler, J.R.; Janocko, M.A.

1991-08-01

73

Design and development of a conformal load-bearing smart skin antenna: overview of the AFRL Smart Skin Structures Technology Demonstration (S3TD)  

NASA Astrophysics Data System (ADS)

Documented herein is a review of progress for the recently completed 'Smart Skin Structure Technology Demonstration' (S3TD) contract number F33615-93-C-3200 performed by Northrop Grumman Corporation, Hawthorne, California and TRW/ASD, Rancho Bernardo, San Diego, California under the Air Force Research Laboratory, Flight Dynamics Directorate, Structures Division's direction and sponsorship. S3TD was conceived as the first serious attempt, to made a complex antenna become a bone fide aircraft structural panel, without loss of overall structural integrity or electrical performance. The program successfully demonstrated the design, fabrication, and structural validation of a load bearing multifunction antenna component panel subjected to realistic aircraft flight load conditions. The final demonstration article was a structurally effective 36 by 36 inch curved multifunction antenna component panel that withstood running loads of 4,000 pounds per inch, and principal strain levels of 4,700 microstrain. Testing the structural component to ultimate, the panel failed at the predicted limit of 148 kips equating to 150 percent design limit load, after successfully completing one lifetime of fatigue. The load conditions were representative of a mid-fuselage F-18 class fighter component panel installation. The panel was designed not to buckle at ultimate failure, and the dominant failure mode was face sheet pull off, as predicted. Structural test data correlated closely with analysis. Wide band electrical performance for the component antenna panel was validated using anechoic chamber measurements and near field probing techniques, covering avionics communication navigation and identification and electronic warfare functions in the 0.15 to 2.2 GHz frequency regimes.

Lockyer, Allen J.; Alt, Kevin H.; Coughlin, Daniel P.; Durham, Michael D.; Kudva, Jayanth N.; Goetz, Allen C.; Tuss, Jim

1999-07-01

74

Photonic wideband array antennas  

Microsoft Academic Search

Presents an introduction to the optical control of array antennas by using fiber optic links for remote control and a photonic time shift network for wide instantaneous bandwidth. An overview of the development of a wideband conformal array designed for airborne surveillance radars is given. The paper covers the system design and the performance of an L-band (850-1400 MHz) M-element

J. J. Lee; R. Y. Loo; S. Livingston; V. I. Jones; J. B. Lewis; Huan-Wun Yen; G. L. Tangonan; M. Wechsberg

1995-01-01

75

The polarizabilities of electrically small apertures of arbitrary shape  

NASA Astrophysics Data System (ADS)

Numerical procedures, based on a method of moments approach, are presented for computing the magnetic and electric polarizabilities of electrically small apertures of arbitrary shape. The magnetic polarizability density is determined by using pulse expansion functions defined over quadrilateral subdomains, while the electric polarizability density is obtained by using basis functions. Each of the basis functions consists of a piecewise arrangement of simple linear functions defined over triangles and having an area coordinate representation. All the subdomains are generated automatically by applying either the Gordon-Hall or the Zienkiewicz-Phillips subdivision methods. Computed results are obtained for several aperture shapes, among them the circle and ellipse.

Okon, E. E.; Harrington, R. F.

1981-11-01

76

SHF SATCOM Microstrip Phased Array Antenna.  

National Technical Information Service (NTIS)

Modern airborne and ground satellite communication systems often require high gain antennas which are low profile and are capable of conforming to a variety of surfaces. A phased array utilizing distributed solid state components is capable of satisfying ...

B. C. Considine D. L. Wandrei

1983-01-01

77

A novel super thin planar car antenna  

Microsoft Academic Search

This paper presents a novel small car antenna, which can be integrated conformally into the bodywork of a car. The antenna, which is intended to be integrated in the car's sunroof or put in the rear mirror, is fed by coaxial cable. In the paper, the prototype and simulation results of 2.4GHz are given. The size of the prototype is

Pengfei Wu; Jinming Pei; Guangjun Liang

2010-01-01

78

Outer-Wall Loop Antenna for Ultrawideband Capsule Endoscope System  

Microsoft Academic Search

The capsule endoscopy system has been used to obtain an image from the inside of the human digestive tract. To acquire high-resolution images, a loop antenna with ultrawide bandwidth is proposed. It is part of the outer wall of the capsule, thus decreasing volume and increasing performance, and uses a meandered line for resonance in an electrically small area. The

Sumin Yun; Kihyun Kim; Sangwook Nam

2010-01-01

79

Metamaterial-inspired magnetic-based UHF and VHF antennas  

Microsoft Academic Search

We have demonstrated that the magnetic-based, metamaterial-inspired electrically small antennas that incorporate a lumped element capacitor can to be scaled to lower frequencies without changing their accepted power performance. This occurs without the intervention of any external matching circuit. On the other hand, the overall efficiency decreases significantly because of conductive losses arising from increasing current densities in the copper

R. W. Ziolkowski; Chia-Ching Lin

2008-01-01

80

A LOW-PROFILE AND BROADBAND CONICAL ANTENNA  

Microsoft Academic Search

A novel electric small conical antenna working on a very broad band, 0.47-6 GHz, with the height of only 60 mm, is presented. A capacitive ring on the top of the cone and three oblique shorted lines are used to expand the work band. By changing the width of the ring and the slope of the oblique line, the impedance

Shi-Gang Zhou; Jie Ma; Jing-Ya Deng; Qi-Zhong Liu

2009-01-01

81

A Novel Reflective Surface for an UHF Spiral Antenna  

Microsoft Academic Search

As is well known, metallic cavity backings reduce antenna gain particularly for broadband configurations at low frequencies. This letter presents a novel reflective surface consisting of a ferrite tile with variable conductive coating as a backing for a conformal UHF spiral antenna. The ferrite material is used in the outer region to preserve the free-space antenna gain at low frequencies.

Brad A. Kramer; Stavros Koulouridis; Chi-Chih Chen; John L. Volakis

2006-01-01

82

Novel ingestible capsule antenna designs for medical monitoring and diagnostics  

Microsoft Academic Search

This paper presents novel antenna designs for electronic digestible capsule pill systems. In the first part, a novel conformal planar offset meandered dipole capsule antenna for medical diagnostics is presented. The antenna performance is evaluated by studying the impedance, radiation, polarization and return loss characteristics inside the human body model. A link budget is evaluated to ensure wireless telemetry. In

Harish Rajagopalan; Yahya Rahmat-Samii

2010-01-01

83

Structural finite-element modeling strategies for conformal load-bearing antenna structure (CLAS) (Air Force contract F33615-C-93-3200)  

NASA Astrophysics Data System (ADS)

As the Wright Lab Air Force military contrast `Smart Skin Structures Technology Demonstration' (S3TD) Contract No. F33615-C-93-3200 draws toward conclusion, pertinent features of the program finite element modeling are presented. Analysis was performed to predict the structural performance of a complex multilayered composite panel that will be tested structurally (and electrically) for the final program deliverable. Application of finite element modeling to predict component load path and strain distribution in sandwich panel construction has been reported elsewhere in the literature for more standard applications. However, the unauthordox sandwich configuration lay-up posed by the quite revolutionary S3TD CLAS aircraft fuselage panel demonstration article merits further discussion. Difficulties with material selection, the stumbling block for many programs, are further exacerbated by conflicting material properties required to support simultaneous electrical and structural performance roles. The structural analysis challenge derives from S3TD's unique program goal, namely, to investigate load bearing antennas structural configurations, rather than conventional structurally inefficient `bolt in' installations, that have been the modus operandi for tactical aircraft antenna installations to date. Discussed below is a cost saving strategy where use of linear finite element analysis has been employed in the prediction of key structural parameters, and validated with risk reduction sub panel measurements, before proceeding to the final fabrication of a full scale 36 by 36 inch CLAS panel demonstration article.

Lockyer, Allen J.; Alt, Kevin H.; Kudva, Jayanth N.; Kinslow, Robert W.; Goetz, Allen C.

1997-06-01

84

Radar Antenna.  

National Technical Information Service (NTIS)

An antenna is described for range-gated, pulse doppler, radar systems. The antenna includes first and second, shortened, half-wave dipoles and first and second reflecting screens. One dipole is fed through a fixed 22 1/2 degree phase-shift network while t...

O. E. Rittenback

1978-01-01

85

Smart-skin antenna technology  

NASA Astrophysics Data System (ADS)

Using smart materials and skins, one could design a smart structure with suitable feedback system architecture. This paper is designed to address some technical advances and applications of smart materials, smart skins and coatings covering a broad spectrum of electromagnetic fields. The Smart Skin Antenna Technology Program's objectives are to (1) use smart skin technologies to develop an antenna system architecture which is structurally integratable, wideband, and embedded/conformal; (2) design, develop, and fabricate a thin, wideband, conformal/arrayable radiator that is structurally integratable and which uses advanced Penn State dielectric and absorber materials to achieve wideband ground planes, and together with low RCS, wideband radomes; (3) implement a smart skin antenna system architecture. Traditional practice has been to design radome and antenna as separate entities and then resolve any interface problems during an integration phase. A structurally integratable conformal antenna, however, demands that the functional components be highly integrated both conceptually and in practice. Our concept is to use the lower skin of the radome as a substrate on which the radiator can be made using standard photolithography, thick film, or LTCC techniques.

Varadan, Vijay K.; Varadan, Vasundara V.

1993-07-01

86

Near-field testing of the 15-meter hoop-column antenna  

Microsoft Academic Search

A 15-m-diameter antenna was tested to verify that dimensional tolerances for acceptable performance could be achieved and to verify structural, electromagnetic, and mechanical performance predictions. This antenna utilized the hoop column structure, a gold plated molybdenum mesh reflector, and 96 control cables to adjust the reflector conformance with a paraboloid. The dimensional conformance of the antenna structure and surface was

Lyle C. Schroeder; Richard R. Adams; M. C. Bailey; W. Keith Belvin; David H. Butler; Thomas G. Campbell

1989-01-01

87

Adjoint sensitivity analysis of an ultrawideband antenna  

SciTech Connect

The frequency domain finite element method using H(curl)-conforming finite elements is a robust technique for full-wave analysis of antennas. As computers become more powerful, it is becoming feasible to not only predict antenna performance, but also to compute sensitivity of antenna performance with respect to multiple parameters. This sensitivity information can then be used for optimization of the design or specification of manufacturing tolerances. In this paper we review the Adjoint Method for sensitivity calculation, and apply it to the problem of optimizing a Ultrawideband antenna.

Stephanson, M B; White, D A

2011-07-28

88

Notched Circular Microstrip Patch Antenna integrated with a single diode rectifier for energy-harvesting prosthetic leg  

Microsoft Academic Search

In this paper, we describe an RF energy- harvesting circuit printed on a single FR4 substrate to ensure compact and low profile design at 2.1 GHz. The circuit integrates a notched Circular Microstrip Patch Antenna (CMPA) with a fully matched single diode rectifier to form an efficient rectifying antenna. By cutting two electrically small triangular notches, at 45 0 and

C. Mikeka; H. Arai

2011-01-01

89

Antenna Support.  

National Technical Information Service (NTIS)

The support is for a large antenna used for distant tracking. The structure includes three tripod assemblies. Each of the assemblies include three extendable and retractable legs having discrete rotatable base portions and top ends rotatable in a framewor...

M. Suliteanu W. R. LaValley

1966-01-01

90

Temperature induced conformational changes in hybrid complexes formed from CdSe/ZnS nanocrystals and the phycobiliprotein antenna of Acaryochloris marina  

NASA Astrophysics Data System (ADS)

In hybrid systems which are self-assembled in solution from surface treated CdSe/ZnS quantum dots (QDs) and isolated phycobiliprotein (PBP) complexes from the cyanobacterium Acaryochloris marina, excitation energy transfer (EET) from the QDs to the PBP complexes was observed. The EET from the QDs to attached PBPs was analyzed with time integrated fluorescence spectroscopy and time-correlated single photon counting (TCSPC) at different temperatures. This functional connection between QDs and PBPs via EET is interrupted at temperatures below 273 K (0 °C) (Schmitt et al 2010 Photon. Nanostruct. submitted). The evaluation of the temperature-dependent fluorescence spectra of the QDs showed that the change of the excitation energy transfer efficiency at temperatures below 273 K cannot be explained by the change of the spectral overlap integral alone. Therefore the value of ?2/R126 must change at 273 K. We assume that micro crystals of water, formed in between the QDs and the PBP antenna structures, lead to a structural change of the hybrid complex. Our results show that TCSPC is suitable to distinguish strongly coupled and weakly coupled QD-PBP complexes at different temperatures.

Schmitt, Franz-Josef

2010-08-01

91

Optical antennas and plasmonics  

Microsoft Academic Search

Optical antenna is a nanoscale miniaturisation of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance conditions for specific metal structures

Q-Han Park

2009-01-01

92

Helix Antenna.  

National Technical Information Service (NTIS)

A helix antenna includes a base portion for containing a feed network including a power input, a 90 degree power splitter in communication with the power inlet, and first and second 180 degree power splitters in communication with the 90 degree power spli...

M. J. Josypenko

1999-01-01

93

Interference Antenna.  

National Technical Information Service (NTIS)

The article describes an interference antenna for a radio telescope which has an irradiator and reflectors and is distinguished by the fact that for the purpose of increasing the resolving power and simplifying the trans mission of energy to the irradiato...

A. P. Molchanov V. M. Vyatkina

1964-01-01

94

Composite right\\/left-handed transmission line based compact resonant antennas for RF module integration  

Microsoft Academic Search

Several electrically small resonant antennas employing the composite right\\/left-handed transmission line (CRLH-TL) are presented for integration with portable RF modules. The proposed antenna designs are based on the unique property of anti-parallel phase and group velocity of the CRLH-TL at its fundamental mode. In this mode, the propagation constant increases as the frequency decreases, therefore, a small guided wavelength can

Cheng-Jung Lee; Kevin M. K. H. Leong; Tatsuo Itoh

2006-01-01

95

WIDEBAND PLANAR SLOT ANTENNAS  

Microsoft Academic Search

In this paper a printed dipole antenna and three slot antennas are designed to operate at 10 GHz for use in radar systems. A parametric study of each antenna and comparison between their radiation properties including return loss, bandwidth, directivity, efficiency and radiation patterns for 6-element linear array are introduced. Slot antennas show wider bandwidth, less coupling and smaller antenna

Abdelnasser A. Eldek; Atef Z. Elsherbeni; Charles E. Smith; Kai-Fong Lee

96

Multicarrier distributed active antenna  

US Patent & Trademark Office Database

A distributed active antenna includes a power module having a parallel combination of power amplifiers for driving each antenna element of the distributed active antenna. A predistortion linearization circuit may be coupled to each power module to linearize the output of each antenna element of the distributed active antenna.

Hoppenstein; Russell (Richardson, TX)

2005-06-14

97

Antenna concept selection  

Microsoft Academic Search

Most essential antenna concepts based on RF configuration with about 3m diameter and 12GHz operation frequency including hybrid system with double rib reflector, hybrid system with one mesh reflector, expandable truss antenna, umbrella type antenna with one mesh reflector, double rib umbrella antenna, and flexible rib antenna with one mesh reflector, as well as their main properties, are used as

E. Frisch; L. Heichele; W. Nagl; H. Popp; W. Schaefer

1975-01-01

98

Piezoceramic actuated aperture antennae  

Microsoft Academic Search

Recently, it has been demonstrated that aperture antennae can have their performance improved by employing shape control on the antenna surface. The antennae previously studied were actuated utilizing polyvinylidene fluoride (PVDF). Since PVDF is a polymer with limited control authority, these antennae can only be employed in space based applications. This study examines more robust antenna structures devised of a

Hwan-Sik Yoon; Gregory Washington

1998-01-01

99

Polydimethylsiloxane membranes for millimeter-wave planar ultra flexible antennas  

Microsoft Academic Search

We present here the use of polydimethylsiloxane (PDMS) membranes as a new soft polymer substrate (?r ap 2.67 at 77 GHz) for the realization of ultra-flexible millimeter-wave printed antennas thanks to the extremely low Young's modulus (EPDMS < 2 MPa). Ultimately this peculiar property enables one to design wide-angle mechanically beam-steering antennas and flexible conformal antennas. The experimental characterization of

Nicolas Tiercelin; Philippe Coquet; Ronan Sauleau; Vincent Senez; Hiroyuki Fujita

2006-01-01

100

Optimizing wearahle UHF antennas for on-body operation  

Microsoft Academic Search

In this paper, we present a wearable antenna design and process using genetic algorithm (GA) optimization. The antenna platform conforms to a human shoulder and all optimization calculations are performed in the presence of the human body. The optimization focuses mostly on the vertically polarized gain pattern (in the azimuth plane) and on matching. The required operational frequency is in

D. Psychoudakis; C.-C. Chen; J. L. Volakis

2007-01-01

101

Link budget analysis and characterization for ingestible capsule antenna  

Microsoft Academic Search

This paper characterizes and analyses the link budget requirements for the conformal capsule antenna in the medical capsule imager system. A link budget is developed for the capsule system based on certain parameters (frequency, SAR, power limitations) and it is shown that using the present antenna system; a reliable communication link can be developed for indoor communication for bio-telemetry applications.

Harish Rajagopalan; Yahya Rahmat-Samii

2010-01-01

102

Dipole Moments of Weak, Electrically Small Emitters from TEM-Cell Measurements.  

National Technical Information Service (NTIS)

The report presents a new method for determining the equivalent electric and magnetic dipole moments of an electrically small emitter from TEM-cell measurements. The electric dipole moments are determined from open-circuit measurements, and the magnetic d...

D. A. Hill K. H. Cavcey

1998-01-01

103

A Miniaturized Planar Space-filling Curve Antenna with Wideband Monopole-like Radiation Characteristics  

Microsoft Academic Search

In this paper, the characteristics of utilizing planar metallic paths in the form of Peano and Hilbert space-filling curves (SFC) are investigated to provide top-loading properties to electrically short monopole antenna elements. Because the higher order SFC curve paths are resonant at frequencies for which the area that encloses the curve can be considered as electrically small, these curves may

John McVay; Ahmad Hoorfar

2006-01-01

104

A compact dual band circularly polarized antenna design for Mars rover mission  

Microsoft Academic Search

Microstrip antennas are widely used in wireless communications due to their advantages of low profile, light weight, low production cost, and conformability with RF circuitry. Recently, a novel reconfigurable microstrip antenna design, patch antenna with switchable slots (PASS), has been proposed to realize various functionalities such as dual frequency operation, dual band CP performance, and polarization diversity with only one

Fan Yang; Yahya Rahmat-Samii

2003-01-01

105

Antenna theory: a review  

Microsoft Academic Search

In this review the author traces the history of antennas and some of the most basic radiating elements, demonstrates the fundamental principles of antenna radiation, reviews Maxwell's equations and electromagnetic boundary conditions, and outlines basic procedures and equations of radiation. Modeling of antenna source excitation is illustrated, and antenna parameters and figures-of-merit are reviewed. Theorems, arraying principles, and advanced asymptotic

CONSTANTINE A. BALANIS

1992-01-01

106

Depolarization in reflector antennas  

Microsoft Academic Search

The recent emergence of antenna applications requiring high polarization purity has focused attention on the depolarizing properties of antenna reflectors. The paper introduces and discusses some concepts of depolarization in the sense of generation of cross-polarization not present for the feed horn of a reflector antenna. The discussion focuses mainly on those applications where the cross-polar properties of the antenna

P. J. Wood

1979-01-01

107

Wearable microstrip antenna  

Microsoft Academic Search

Microstrip antennas are being used as a representative antenna for mobile and satellite communication. The microstrip antennas have features such as planarity and a relatively high gain (about 7 dBi). It is typical to fabricate them by using hard substrates. However, these substrates are limited in shape and mounting placement for fixing such an antenna to clothing or hats. Therefore,

M. Tanaka; Jae-Hyeuk Jang

2003-01-01

108

A short dipole antenna  

Microsoft Academic Search

In order to reduce the effective area of the receiving antenna to receiving microwave power in high electric field regions, a short dipole antenna is investigated numerically and experimentally in this paper. The short dipole antenna is a variation of the conventional half-wave antenna. A 50 ? coaxial transmission line with two symmetrical narrow slots is employed as a feeder

Yu-Wei Fan; Hui-Huang Zhong; Zhi-Qiang Li; Heng Zhou; Wei-Hong Zhou; Jun Zhu; Ling Luo

2008-01-01

109

Cross Resonant Optical Antenna  

Microsoft Academic Search

We propose a novel cross resonant optical antenna consisting of two perpendicular nanosized gold dipole antennas with a common feed gap. We demonstrate that the cross antenna is able to convert propagating fields of any polarization state into correspondingly polarized, localized, and enhanced fields and vice versa. The cross antenna structure therefore opens the road towards the control of light-matter

P. Biagioni; J. S. Huang; L. Duò; M. Finazzi; B. Hecht

2009-01-01

110

Effectiveness of active antennas  

Microsoft Academic Search

Active antennas are miniaturized radio-receiver antennas which use broadband transistor amplifiers to effect added voltage. The effectiveness of such an antenna is the signal to noise ratio at the input of the amplifier. This paper presents an analysis of the noise properties of the most widespread active antenna - a short asymmetrical vibrator with a high-impedance broadband amplifier. It is

B. V. Sosunov

1976-01-01

111

Conformal microstrip patch circular array with orthogonal conformal stripline feed and all-angle transition  

Microsoft Academic Search

A prototype Ku-band, 32-element, circular microstrip patch array connected to a conformal stripline feed with an orthogonal all-angle transition was designed, fabricated and tested. The low cost antenna uses standard printed circuit technology. The antenna consists of a stripline feed conformally encased in a metal ring orthogonal to microstrip patch radiating elements which are etched on the front Duriod 5880

R. T. Cock; R. D. Cook

1997-01-01

112

Investigation of superimposed dichroic microstrip antennas  

NASA Astrophysics Data System (ADS)

It is shown here that finite mesh arrays can be superimposed on microstrip arrays to create compact, dual-purpose antenna apertures. Practical array configurations are described to illustrate the dual-function performance that can be obtained from a single conformal aperture. Conclusions are reached as to the usefulness of the technique, its extension to millimeter wavelengths, and other engineering issues.

Andrasic, G.; James, J. R.

113

Circularly polarized active circulator smart skin antenna  

Microsoft Academic Search

In search for low cost circularly polarized active circulator radiating conformal patch (paste-on) structure, so called smart skin antenna, a novel approach employing combination of phase cancellation technique and perturbation segments in the form of truncated corner of the patch is reported. This paper presents a review of active circulator design and it's comparative performances to suit trans-receive applications. Much

A. K. Poddar; K. N. Pandey

2000-01-01

114

Experimental Study of the Effect of Paint on Embedded Automotive Antennas  

Microsoft Academic Search

In years have seen the advent of new types of automotive antennas, such as blade or 'shark-fin' antennas and conformal planar roof mounted antennas. In many cases it is desirable to paint these antennas to improve the appearance of the vehicle. In this communication we present an investigation of the effect that both metallic and non-metallic two-pack polyurethane paint has

Brendan Pell; Wayne Rowe; Edin Sulic; Kamran Ghorbani; Sabu John; Rahul Gupta; Kefei Zhang; Brian Hughes

2008-01-01

115

Smart antennas for wireless systems  

Microsoft Academic Search

In this article we discuss current and future antenna technology for wireless systems and the improvement that smart and adaptive antenna arrays can provide. We describe standard cellular antennas, smart antennas using fixed beams, and adaptive antennas for base stations, as well as antenna technologies for handsets. We show the potential improvement that these antennas can provide, including range extension,

JACK H. WINTERS

1998-01-01

116

A metamaterial-inspired, electrically small rectenna for high-efficiency, low power harvesting and scavenging at the global positioning system L1 frequency  

NASA Astrophysics Data System (ADS)

An electrically small rectenna was designed and tested at the global positioning system (GPS) L1 frequency (1.5754 GHz). The metamaterial-inspired near-field resonant parasitic antenna size (ka ~ 0.467) and its direct match to the input impedance of the rectifying circuit decreased the whole size of the rectenna (ka ~ 0.611). The simulated and measured rectifying efficiencies were, respectively, 75.7% and 79.6% when the input power to the rectifying circuit was 0.0 dBm (1 mW). The highest rectifying efficiency, 84.7%, was achieved at the GPS L1 frequency for a 3.0 dBm input power. The simulated and measured results are in good agreement.

Zhu, Ning; Ziolkowski, Richard W.; Xin, Hao

2011-09-01

117

Statistical Properties of Antenna Impedance in an Electrically Large Cavity  

SciTech Connect

This paper presents models and measurements of antenna input impedance in resonant cavities at high frequencies.The behavior of input impedance is useful in determining the transmission and reception characteristics of an antenna (as well as the transmission characteristics of certain apertures). Results are presented for both the case where the cavity is undermoded (modes with separate and discrete spectra) as well as the over moded case (modes with overlapping spectra). A modal series is constructed and analyzed to determine the impedance statistical distribution. Both electrically small as well as electrically longer resonant and wall mounted antennas are analyzed. Measurements in a large mode stirred chamber cavity are compared with calculations. Finally a method based on power arguments is given, yielding simple formulas for the impedance distribution.

WARNE,LARRY K.; LEE,KELVIN S.H.; HUDSON,H. GERALD; JOHNSON,WILLIAM A.; JORGENSON,ROY E.; STRONACH,STEPHEN L.

2000-12-13

118

Automated calibration and data reduction technique for electrically small electromagnetic field sensors  

Microsoft Academic Search

An automatic technique for calibrating electrically small electromagnetic field sensors utilizing a transmission cell is presented. The standard field method was chosen for this application because of the increased accuracy and the elimination of intermediate steps in the process necessary to implement a fast automatic calibration technique. The standard field is produced by utilizing a transverse electromagnetic (TEM) transmission cell.

Brian E. Strickland; N. F. Audeh

1990-01-01

119

Employment of non-Foster active loads to improve the operation bandwidth of SRR loaded monopole antennas  

Microsoft Academic Search

In this contribution, we theoretically and numerically show that the operation bandwidth of an electrically small SRR loaded monopole antenna can be improved by using non-Foster active elements connected to the external gap of the SRR. The circuit implementation of the required non-Foster load in the VHF frequency band, as well as the stability analysis of the whole active component

M. Barbuto; A. Monti; F. Bilotti; A. Toscano

2012-01-01

120

Development of antenna systems (Review)  

Microsoft Academic Search

Trends in the development of the theory and technology of antenna systems are surveyed. Particular consideration is given to the improvement of the degree of signal processing in the antenna; antenna control characteristics; the synthesis of antenna systems; the computer-aided design and manufacturing of antenna systems; EMC assurance; and antenna design features.

D. I. Voskresenskii; V. M. Maksimov

1987-01-01

121

VLF Loop Array Antenna.  

National Technical Information Service (NTIS)

The report describes a directional loop array antenna for very low frequency (VLF) reception. The array comprises four closely spaced loop antennas forming a unidirectional reception pattern with a main beam of less than 43 deg between half power points. ...

E. W. Seeley

1978-01-01

122

Serpentine Buoyant Cable Antenna.  

National Technical Information Service (NTIS)

The present invention relates to an improved buoyant cable antenna system. The system includes a buoyant cable transmission line segment and an antenna segment formed from a flexible memory structure comprised of at least one segment of coiled compression...

E. M. Gerhard

2006-01-01

123

Antenna measurement techniques  

Microsoft Academic Search

The principles and procedures of microwave antenna testing are discussed in an introduction for antenna and test-range designers. Chapters are devoted to antenna testing and range types, far-field range design, far-field tests, far-field pattern errors, compact ranges, near-field testing, radar cross sections, time-domain antenna measurements, and small-radiator measurements. Diagrams, drawings, graphs, photographs, and a glossary of terms are provided.

Gary E. Evans

1990-01-01

124

What's new in antennas?  

NASA Astrophysics Data System (ADS)

Innovative designs and ideas in antenna technology are addressed. The fundamental properties and degrees of design freedom in antennas are reviewed, and the driving forces for research and development are indicated. New developments in antenna elements, traveling-wave arrays, apertures, arrays, measurements, and material developments are considered. CAD is examined as the leading edge of design, and the future of antenna technology is briefly discussed.

James, J. R.

125

Resonant Optical Antennas  

Microsoft Academic Search

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations

P. Mühlschlegel; H.-J. Eisler; O. J. F. Martin; B. Hecht; D. W. Pohl

2005-01-01

126

Near field antennas measurements using photonic antenna  

Microsoft Academic Search

The paper presents a near-field antenna measurements solution using a fiber-optic techniques to improve phase measurements accuracy. Main problem in near-field antenna measurements is phase distortions from changes of cable geometry during the measurements. Measurement solution has been proposed, which allows to illuminate phase errors and consequently to enhance measurement accuracy comparing with conventional technique.

Yevhen Yashchyshyn; Josef Modelski; Sergei Malyshev; Alexander Chizh; Maxim Svirid; P. Wegrzyniak

2007-01-01

127

Silicon based reconfigurable antennas  

Microsoft Academic Search

Summary form only given. Selects solid-state plasmas generated by PIN junctions to effectively implement various reconfigurable antennas. Other alternative technologies include MEMs switches to reconfigure antennas. PIN junctions can also be utilized as switches, and can replace MEMs to reconfigure antennas where speed of response is an issue. We have utilized these PIN junctions to dynamically define plasma regions with

A. Fathy; A. Rosen; F. McGinty; G. Taylor; S. Perlow; M. ElSherbiny

2000-01-01

128

Wlan Jacket Mounted Antenna  

Microsoft Academic Search

A novel antenna mounted on a textile jacket is presented which arises from previous research work on metal button structures for wearable antennas. The antenna has the dimensions of metallic buttons used in denim clothing. The dimensions have been reduced compared to previously reported designs and this is achieved using dielectric material between two parallel metal plates and a displaced

B. Sanz-Izquierdo; J. C. Batchelor

2007-01-01

129

Dual band wearable antenna  

Microsoft Academic Search

An antenna fabricated using clothing materials is presented. The antenna operates over the wireless network bands at 2.45 Hz and 5 GHz. An electromagnetic band gap surface is used to reduce back radiation by 10 to 15 dB while maintaining the impedance match over the two frequency bands. Coupling between antennas is significantly reduced making it ideal for body worn

Richard Langley; Shaozhen Zhu

2008-01-01

130

The equiangular spiral antenna  

Microsoft Academic Search

A circularly polarized antenna is described which makes possible bandwidths that a few years ago were considered to be impossible. The design of the antenna is based upon the simple fundamental principle that if the shape of the antenna were such that it could be specified entirely by angles, its performance would be independent of wavelength. Since all such shapes

J. Dyson

1959-01-01

131

Optical antenna thermal emitters  

Microsoft Academic Search

Optical antennas are a critical component in nanophotonics research and have been used to enhance nonlinear and Raman cross-sections and to make nanoscale optical probes. In addition to their ‘receiving’ properties, optical antennas can operate in ‘broadcasting’ mode, and have been used to modify the emission rate and direction of individual molecules. In these applications the antenna must operate at

Jon A. Schuller; Thomas Taubner; Mark L. Brongersma

2009-01-01

132

Deployable microwave lens antennas  

Microsoft Academic Search

Because of their large mass, waveguide lens antennas have not been widely used in space, in spite of their established superiority to reflector antennas for many aerospace applications. This paper introduces the concept of fabrication of lightweight waveguide lenses using thin, metallized polymer sheets. It also presents preliminary simulation results to substantiate and illustrate the characteristics of lens antennas.

Massih Hamidi; James Withington; Eric Wiswell

2002-01-01

133

Analysis of branched antennas  

Microsoft Academic Search

After a review of antenna theory (vibrators, arrays, etc.), a system of integral equations is obtained for calculating the current distribution on the conductors of branched antennas for prescribed electromotive forces and taking account of the mutual interactions of array antennas. The radio-technical parameters (which condition the efficiency with which the energy of constrained electromagnetic waves is converted into the

L. M. Indichenko

1975-01-01

134

Polarimetric SAR antenna characterization  

NASA Astrophysics Data System (ADS)

A procedure is described for obtaining the two-way polarimetric properties of a Synthetic Aperture Radar (SAR) antenna from one-way measurements in a compact antenna test range. The two-way properties are determined by involving reciprocity and computing a polarization distortion matrix (PDM). Next, one-way antenna-only measurements are combined with boresight measurements of the complete system to find an overall PDM. Polarimetric distortions caused by the antenna can be compensated using the inverse of the PDM; however, the Advanced Detection Technology Sensor antenna was found to have adequately low crosspolarization without the need for crosspolarization compensation.

Barnes, Richard M.; Blejer, Dennis J.

1989-07-01

135

The ALMA antenna procurement  

NASA Astrophysics Data System (ADS)

Visitors who come to the OSF at regular intervals find a growing population of antennas at various stages of assembly and testing. The long path from the start of the definition of antenna specifications to the start of science operations with the antennas was and still is a formidable endeavor. When completed, ALMA will comprise a 12-meter diameter antennas array, the bilateral interferometer array, of a minimum of fifty antennas and in addition, the ACA (Atacama Compact Array), composed of four 12-meter diameter antennas and twelve 7-meter diameter antennas. Out of the fifty antennas of the bilateral interferometer array, one-half are provided by the North American partners of ALMA, the other half by the European partners. The sixteen antennas that will comprise the ACA are provided by the East Asian Partners of ALMA. Here we review some key points of this challenging process and we provide a brief history and status of the ALMA antennas. Because of the length of the description, we will present this in a series of two articles. In this first part we concentrate mostly on the bilateral antenna procurement. A detailed description of the ACA will be presented in the next newsletter.

Stanghellini, S.; Zivick, Jeff; Inatani, Junji

2009-10-01

136

JPL antenna technology development  

NASA Astrophysics Data System (ADS)

Plans for evaluating, designing, fabricating, transporting and deploying cost effective and STS compatible offset wrap rib antennas up to 300 meters in diameter for mobile communications, Earth resources observation, and for the orbiting VLBI are reviewed. The JPL surface measurement system, intended for large mesh deployable antenna applications will be demonstrated and validated as part of the antenna ground based demonstration program. Results of the offset wrap rib deployable antenna technology development will include: (1) high confidence structural designs for antennas up to 100 meters in diameter; (2) high confidence estimates of functional performance and fabrication cost for a wide range of antenna sizes (up to 300 meters in diameter); (3) risk assessment for fabricating the large size antennas; and (4) 55 meter diameter flight quality hardware that can be cost effectively completed toto accommodate a flight experiment and/or application.

Freeland, R. E.

1981-02-01

137

Modeling the electromagnetic radiation from electrically small table-top products  

Microsoft Academic Search

A bstruct-Often, the most difficult radiated electromagnetic interfer- ence (EMI) problems with table-top products occur at frequencies where the maximum dimensions of the product are much smaller than a wave- length. Electrically small table-top products tend to be much more effi- cient radiation sources than dipole source models would predict and the radiation is generally much more difficult to contain

T. H. Hubing; J. F. Kauffman

1989-01-01

138

Monopulse antennas for radar seekers  

Microsoft Academic Search

The paper presents some most important design issues of antennas with modelled monopulse radiation pattern in both azimuth and elevation, especially of dielectric substrate microstripe antenna structures. An approach to optimisation of the antenna patterns is discussed and an example of circular antenna array solution is presented. The issue of feeding such antenna arrays is discussed. The solution of decomposition

P. Gajewski; W. Kolosowski; J. Lopatka; A. Jeziorski

2008-01-01

139

Ultra-Large Antennas  

NASA Astrophysics Data System (ADS)

Two kinds of ultra-large antennas are required for SPS. The one is called a spacetenna which transmits an enormous amount of a microwave, and the other is called a rectenna which receives and rectifies the microwave. As all microwave power in a transmitted beam has to be received by the rectenna, the beam width should be quite narrow. Accordingly, the diameters of both antennas are quite large: For example, in the Reference System of NASA, the spacetenna and rectenna are, 1 km and 3 km in diameter, respectively. Moreover on the spacetenna, several requirements are imposed for space use. In order to construct an ultra-large antenna, several schemes were proposed, and technical issues were clarified. Novel technologies have been studied and proposed in Japan so far. Launch, assembling and testing of ultra-large antennas are also important. This paper describes the peculiarities of these antennas in comparison with conventional large antennas. Relevant technologies will be also presented.

Takano, Tadashi

140

Design and comparison between two general purpose dipole type UHF RFID tag antennas  

Microsoft Academic Search

Two short-dipole type RFID tags with diverse geometries have been developed to compare their performance with each other and with two commercial short-dipole type tags. Antenna structures were modelled with FEM-simulator to find a suitable geometries for matching and radiation properties. Based on simulation and measurement results bowtie design proved to be more apt geometry for an electrically small radiator

M. Nikkari; T. Bjorninen; L. Ukkonen; Fan Yang; A. Elsherbeni; L. Sydanheimo; M. Kivikoski

2008-01-01

141

Enhanced Directivity From Subwavelength Infrared\\/Optical Nano-Antennas Loaded With Plasmonic Materials or Metamaterials  

Microsoft Academic Search

Here, we explore theoretically the concept of enhanced directivity from electrically small subwavelength radiators containing negative-parameter materials, such as plasmonic materials with negative permittivity at THz, infrared and optical frequencies. In particular, we study higher order plasmonic resonances of a subwavelength core-shell spherical nano-antenna, and we analyze the near-zone field distributions and far-field radiation patterns of such a structure when

Andrea Alu; Nader Engheta

2007-01-01

142

Detailed antenna design  

Microsoft Academic Search

A focus fed parabolic antenna is described as well as the RF-performance goals (frequency from 11.7 to 12.5 GHz, -23dB sidelobe level, 45% beam-width circularity, and 0.1 beamwidth accuracy). The degradation of efficiency and increase of sidelobe level in the realistic antenna configuration are estimated. The effects degrading the RF performance of the focus fed antenna are summarized. To meet

J. Ederle; L. Heichele; W. Nagl; H. Wolter

1975-01-01

143

CDMA Smart Antenna Performance  

Microsoft Academic Search

Applications of smart antenna technology to CDMA networks include both high-mobility cellular\\/PCS as well as fixed-terminal\\u000a and low-mobility wireless local hop deployments. Smart antennas are emerging as an integral element of the new wideband CDMA\\u000a standards for third generation mobile telephone systems across North America, Europe and Asia. This paper proposes a realizable\\u000a architecture that applies smart antennas to current

Martin J. Feuerstein; J. Todd Elson; Michael A. Zhao; Scot Gordon

144

The single antenna interferometer  

SciTech Connect

Air and space borne platforms using synthetic aperture radars (SAR) have made interferometric measurements by using either two physical antennas mounted on one air-frame or two passes of one antenna over a scene. In this paper, a new interferometric technique using one pass of a single-antenna SAR system is proposed and demonstrated on data collected by the NASA-JPL AirSAR. Remotely sensed L-band microwave data are used to show the sensitivity of this technique to ocean surface features as well as a baseline for comparison with work by others using two-antenna systems. 7 refs., 3 figs.

Fitch, J.P.

1990-01-15

145

MASTER TELEVISION ANTENNA SYSTEM.  

ERIC Educational Resources Information Center

|SPECIFICATIONS FOR THE FURNISHING AND INSTALLATION OF TELEVISION MASTER ANTENNA SYSTEMS FOR SECONDARY AND ELEMENTARY SCHOOLS ARE GIVEN. CONTRACTOR REQUIREMENTS, EQUIPMENT, PERFORMANCE STANDARDS, AND FUNCTIONS ARE DESCRIBED. (MS)|

Rhode Island State Dept. of Education, Providence.

146

Soviet articles on antenna theory  

SciTech Connect

Translations of two pioneering Russian papers on antenna theory are presented. The first paper provides a treatise on finite-length dipole antennas; the second paper addresses infinite-length, impedance-loaded transmitting antennas.

Chen, K.C. [ed.

1992-01-01

147

A compact annular ring microstrip antenna for WSN applications.  

PubMed

A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 ?) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and -2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels. PMID:23012510

Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

2012-06-26

148

Deployable antennae design alternatives  

Microsoft Academic Search

To have a large spectrum of design and decision criteria, some RF configurations of microwave reflector antennas which seem to achieve the best RF properties, especially in a deployable configuration, are considered. Antenna concepts suitable for the 12 GHz range (high surface accuracy, low weight, and high stiffness) were considered. An RF configuration with about 3m diameter and 12 GHz

E. Frisch; L. Heichele; W. Nagl; H. Popp; W. Schaefer

1975-01-01

149

Les-6 Antenna System.  

National Technical Information Service (NTIS)

The antenna system for a sixth experimental satellite (LES-6) is described. It is the first circularly polarized, despun, VHF antenna to be successfully used on an orbiting satellite. A relatively high-gain (11-db peak) beam is electronically scanned to b...

R. N. Assaly M. E. Devane B. F. LaPage M. L. Rosenthal A. Sotiropoulos

1969-01-01

150

Deployable Ground Plane Antenna.  

National Technical Information Service (NTIS)

A deployable ground plane antenna for use aboard a satellite or the like, with the antenna and erection mechanism being compactly stowable within the confines of a launch vehicle prior to and during launch thereof is described. After ejection of the satel...

L. Schwerdtfeger

1977-01-01

151

Coaxial Horn Antenna System.  

National Technical Information Service (NTIS)

An antenna feed system includes a plurality of RF born antennas (201, 202) for operating on a plurality of RF frequency bands. A first one of the feed horns (202) can have a bore-sight axis and is configured for operating at a first one of the frequency b...

J. A. Kralovec G. K. Gothard T. E. Durham

2003-01-01

152

Experiments with Dipole Antennas  

ERIC Educational Resources Information Center

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…

Kraftmakher, Yaakov

2009-01-01

153

Experiments with Dipole Antennas  

ERIC Educational Resources Information Center

|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…

Kraftmakher, Yaakov

2009-01-01

154

Milestones in Broadcasting: Antennas.  

ERIC Educational Resources Information Center

|Briefly describes the development of antennas in the prebroadcast era (elevated antenna, selectivity to prevent interference between stations, birth of diplex, directional properties, support structures), as well as technological developments used in long-, medium-, and short-wave broadcasting, VHF/FM and television broadcasting, and satellite…

Media in Education and Development, 1985

1985-01-01

155

Advanced composite antenna development  

Microsoft Academic Search

This paper presents a designed, fabricated, and tested antenna terminal employing advanced composite materials. The antenna demonstrated the advantage these materials have in providing a more compact, lower weight system, while meeting required performance in a cost effective manner. The work was specifically oriented toward the requirements and objectives of the Naval Electronics Command for the development of a lightweight,

J. H. Heathman; R. S. Wilson

1977-01-01

156

Optimization of director antennas  

Microsoft Academic Search

The optimization of director antennas is considered in the rigorous electrodynamic formulation, and numerical results on such optimization are presented. A software package has been created which makes it possible to optimize (with acceptable machine time) the antenna geometry to achieve a maximum directive gain with a number of directors up to 20. An appropriate selection of vibrator lengths and

A. F. Chaplin; M. D. Buchatskii; M. Iu. Mikhailov

1983-01-01

157

Advanced design methodologies and novel applications of reflectarray antennas  

NASA Astrophysics Data System (ADS)

Reflectarray antennas combine the numerous advantages of printed antenna arrays and reflector antennas and create a hybrid high-gain antenna with a low-profile, low-mass, and diversified radiation performance. Reflectarrays are now emerging as the new generation of high-gain antennas for long-distance communications. In this dissertation, some advanced concepts demonstrating novel features of reflectarray antennas are presented. • First, various approaches for radiation analysis of reflectarray antennas are described and implemented. Numerical results are then presented for a variety of systems and the advantages, limitations, and accuracy of these approaches are discussed and compared with each other. • A broadband technique by using sub-wavelength elements is proposed and prototypes are fabricated and tested. This technique enables the reflectarray to achieve a significant bandwidth improvement with no additional cost. • Infrared reflectarrays antennas are studied for possible applications in concentrating solar power systems. Material losses, an important design issue at infrared frequencies, are investigated and reflectarrays consisted of dielectric resonant elements are proposed with low-loss features at infrared. • Multi-beam reflectarray antennas are studied and it is demonstrated that by optimizing the phase of the elements, a desirable multi-beam performance can be achieved using a single-feed. Local and global phase-only optimization techniques have been implemented. Two Ka-band quad-beam prototypes with symmetric and asymmetric beams have been fabricated and tested. • Different approaches for beam-scanning with reflectarray antennas are also reviewed and it is shown that for moderately wide angle beam-scanning, utilizing a feed displacement technique is more suitable than an aperture phase tuning approach. A feed displacement beam-scanning design with novel aperture phase distribution is proposed for the reflectarray antenna, and is further optimized to improve the performance. A high-gain Ka-band prototype achieving 60 degrees scan range with side-lobe levels below 15 dB is demonstrated. • The feasibility of designing reflectarray antennas on conformal surfaces is also studied numerically. A generalized analysis approach is presented and the radiation performance of reflectarray antennas on singly-curved conformal cylindrical platforms are studied and compared with their planar counterpart. It is revealed that conformal reflectarray antennas are a suitable choice for a high-gain antenna where curved platforms are required. In summary, different challenges in reflectarray analysis and design are addressed in this dissertation. On the element design challenges, bandwidth improvement and infrared operation of reflectarray antennas have been studied. On the system level challenges, multi-beam designs, beam-scanning performance, and conformal platforms have been investigated. Several prototypes have been fabricated and tested, demonstrating the novel features and potential applications of reflectarray antennas.

Nayeri, Payam

158

NASA Antenna Gets its Bearings  

NASA Video Gallery

The historic "Mars antenna" at NASA's Deep Space Network site in Goldstone, Calif. has finished a major, delicate surgery that lasted seven months. The operation on the giant, 70-meter-wide (230-foot) antenna replaced the hydrostatic bearing assembly, which enables the antenna to rotate horizontally, and the elevation bearings, which enable the antenna to track up and down from the horizon.

Luis Espinoza

2010-11-01

159

UWB Antennas and Their Applications  

Microsoft Academic Search

The UWB antennas are proposed for applications of communication systems, various kinds of antenna test ranges, and high resolution microwave imaging. The narrower instantaneous bandwidth of UWB antennas will degrade the performance of the above applications. By using different characteristic of geometries, structures and sizes, good impedance bandwidth and instantaneous bandwidth can be achieved for these UWB antennas. In this

Dau-Chyrh Chang

2008-01-01

160

Antenna measurements using radioastronomical techniques  

Microsoft Academic Search

The gain, half power beam width (HPBIV), and average values of the sidelobe attenuation of large antennas have been measured using radioastronomical techniques. Figure 1 shows an arrangement of antenna, radiometer, and temperature calibration system which has been used for antenna measurements. The radiometer is a total power receiver. The radiation power collected by the antenna is amplified together with

Peter G. Metzger

1964-01-01

161

Transmission coupler antenna  

NASA Astrophysics Data System (ADS)

A broad band HF communications antenna for surface ships has an increased survivability over the currently used twin fan antennas. Capacitively coupling a long, flat conductive strap to existing ship structures helps achieve broadband performance. Integral end sections of the long, flat conductive strap are bent at each end and a dielectric layer with a low dielectric constant is provided along the length of each end section. The end sections and dielectric layers provide the areas needed for capacitive coupling to a mast and stack or other parts of the ship's superstructure thereby creating a survivable and broadband HF communications antenna design.

Abramo, Robert S.

1991-05-01

162

Antenna fundamentals: A tutorial paper  

NASA Astrophysics Data System (ADS)

The principles and characteristics of antennas, operating in the radio frequency band, are examined. A descriptive approach with the minimum of mathematical derivation is given. The antenna and radiation definitions, and terms are considered. The characteristics and applications of linear, aperture and specialized antennas are emphasized. The techniques discussed can be adapted and modified to tackle and evaluate whatever new antenna types the future will offer. A list of the leading parameters of the more common, contemporary antenna types, is given.

Robertson, J. C.

1988-01-01

163

Control of electromagnetic edge effects in electrically-small rectangular plasma reactors  

SciTech Connect

Electromagnetic fields supported by rectangular reactors for plasma enhanced chemical vapor deposition are studied theoretically. Expressions for the fields in an electrically-small rectangular reactor with plasma in the chamber are derived. Modal field decompositions are employed under the homogeneous plasma slab approximation. The amplitude of each mode is determined analytically. It is shown that the field can be represented by the standing wave, evanescent waves tied to the edges, and an evanescent wave tied to the corners of the reactor. The impact of boundary conditions at the plasma edge on nonuniformity is quantified. Uniformity may be improved by placing a lossy magnetic layer on the reactor sidewalls. It is demonstrated that nonuniformity is a decreasing function of layer thickness.

Trampel, Christopher P.; Stieler, Daniel S. [Department of Electrical and Computer Engineering, Iowa State University, 2215 Coover Hall, Ames, Iowa 50011 (United States); PowerFilm, Inc., 2337 230th Street, Ames, Iowa 50014 (United States)

2012-09-15

164

SATCOM Electronic Scan Antenna.  

National Technical Information Service (NTIS)

In this final report is presented the progression of the electronic scan antenna research highlighting the key results and stumbling blocks throughout this SBIR phase II period. The original premise was to use the FLAPS technology, a Malibu Research paten...

2000-01-01

165

Wullenwebber Antenna Vibration Study.  

National Technical Information Service (NTIS)

The U. S. Navy is completing a world-wide radio directional antenna system, which has exhibited an undesirable wind induced oscillation of one of the primary structural members, resulting in physical damage and failure. Oscillations at some installations ...

R. L. Breckon P. R. Hite

1965-01-01

166

Performance of Short Antennas  

Microsoft Academic Search

The purpose of this paper is to present experimental data on the performance of vertical antennas having a physical height of less than one-eighth wavelength. These data cover many conditions of top loading performed on a 300-foot, self-supporting, tapered vertical tower with measurements of antenna resistance and reactance from 120 to 400 kilocycles. For these conditions, field-intensity measurements were made

C. E. Smith; E. M. Johnson

1947-01-01

167

UHF antenna choices  

Microsoft Academic Search

The implementation of DTV is forcing every television broadcaster to purchase a new antenna. Choosing the best antenna to meet all of the station's needs is not a simple task. With tower space at a premium, tower leasing rates soaring, and FCC deadlines approaching quickly, the broadcaster faces new and non-traditional issues-for example: Do I co-locate with others? Do I

D. Casciola; G. L. Miers; R. A. Surette

1999-01-01

168

Antenna pattern measurement facilities  

NASA Astrophysics Data System (ADS)

The test operations procedure (TOP) is an overview of procedures for testing antennas using the Automated Data Acquisition and Analysis System (ADAAS) at the Antenna Test Facility (ATF), U.S. Army Electronic Proving Ground, Fort Huachuca, Arizona. The ATF has two test ranges: an outdoor compact range and an arc range. The Compact Range uses a parabolic reflector to collimate radio frequency energy in order to simulate far-field testing. A large hydraulic positioner moves the test antenna through azimuth and elevation arcs to allow testing of an entire hemisphere of coverage. The Arc Range operates in the near field using uncollimated RF. It uses a turntable to rotate the test item through the desired range of azimuth; a probe antenna moving along the vertical arc structure provides elevation coverage. The combination provides full hemispherical coverage. The TOP describes procedures for measuring antenna gain; locations of beams, lobes, and nulls; and other antenna characteristics. It contrasts the capabilities of the two ranges and provides guidelines to help the user select the right range for a particular test.

1992-04-01

169

Technologies and applications of microwave photonic antennas  

Microsoft Academic Search

This paper describes the development of microwave photonic antennas concepts and their applications. The experimental study of the transmitting and receiving photonic antenna are shown. The transmitting photonic antenna consists of photodiode integrated with microstrip E-shaped patch antenna, and receiving photonic antenna consists of laser diode integrated directly with the Vivaldi antenna.

Y. Yashchyshyn; A. Chizh; S. Malyshev; J. Modelski

2010-01-01

170

MMIC antenna front end for optically distributed MMW antennas  

Microsoft Academic Search

It is well documented that fiber optic remoting of information to the millimeter wave distributed antennas is viable only when the modulated carrier is constructed at the antenna front end. The MMIC based antenna front is designed to perform the three important functions of: generation of a phase and frequency stable local oscillator; down-conversion (up-conversion) of the modulated RF (IF)

Dana Sturzebecher; Xiangdong Zhang; Afshin S. Daryoush

1995-01-01

171

Ionospheric Effects on Antenna Impedance.  

National Technical Information Service (NTIS)

The reciprocity between high power satellite antennas and the surrounding plasma are examined. The relevant plasma states for antenna impedance calculations are presented and plasma models, and hydrodynamic and kinetic theory, are discussed. A theory from...

K. H. Bethke

1984-01-01

172

Ionospheric Effects to Antenna Impedance.  

National Technical Information Service (NTIS)

The reciprocity between high power satellite antennas and the surrounding plasma are examined. The relevant plasma states for antenna impedance calculations are presented and plasma models, and hydrodynamic and kinetic theory, are discussed. A theory from...

K. H. Bethke

1986-01-01

173

PASS spacecraft antenna technology assessment  

NASA Astrophysics Data System (ADS)

The purpose was to generate estimates of mechanical performance for the classes of spacecraft antenna under construction for application to the Personal Access Satellite System (PASS). These performance data are needed for the support of trade studies involving antenna system development. The classes of antenna considered included: (1) rigid non-deployable antenna structures; (2) mechanical deployable antenna concepts; (3) inflatable deployable antenna concepts; and (4) mesh deployable antenna concepts. The estimates of mechanical performance are presented in terms of structural weight and cost as a function of the reflector size. Estimates of aperture surface precision are presented for a few discrete antenna sizes. The range of reflector size is 1 to 4 meters for non-deployable structures and 2 to 8 meters for deployable structures. The range of reflector surface precision is lambda/30 to lambda/50 for 20 and 30 GHz, respectively.

Freeland, R. E.

1990-09-01

174

Photonic systems for antenna applications  

Microsoft Academic Search

For well over a decade, research groups around the world have been investigating photonic devices for use in antenna, phased-array, and electromagnetic-field-sensor systems. Proposed applications include EMC monitoring, EMP measurements, anechoic-chamber calibration, novel antenna and array designs, remotely located antennas, and smart skins. Photonic antenna links allow immunity from electromagnetic interference, provide an extremely wide working bandwidth, and allow long

M. L. VanBlaricum

1994-01-01

175

An active downlink photonic antenna  

Microsoft Academic Search

This paper presents an active photonic antenna concept whereby an interface circuit is introduced in order to integrate the antenna with the photodiode. The operating frequencies ranges are 1.8 to 3.5 GHz which support the GSM 1800, WLAN and WiMAX applications. The simulated and measured results of interface circuit and antenna are presented. Thus, the photonic antenna is developed by

N. F. Nanyan; R. Ngah; T. Prakoso; Y. Rahayu; T. A. Rahman

2010-01-01

176

Launching large antennas  

NASA Astrophysics Data System (ADS)

Large antennas will provide communication to rural and remote areas in times of need. This is seen as facilitating the work of law enforcement agencies. All mobile radio communications will enjoy advantages in distances covered and information relayed owing to the large number of beams possible from super radio transmitters in space. If the antennas are placed in low-earth orbit, advantages will be realized in the remote sensing of the earth's resources. It is pointed out that with umbrella or bicyclelike antennas turned outward toward space, the universe could be scouted for signals from intelligent life. Various concepts that have been put forward by U.S. companies are described. These include the radial rib, wrap rib, and parabolic erectable truss designs. Others are the mesh hoop column collapsable umbrella made of gold and molybdenum and the maypole design.

Brandli, H. W.

1983-09-01

177

Electromagnetic exposure in a phantom in the near and far fields of wire and planar antennas  

NASA Astrophysics Data System (ADS)

Due to the wide availability and usage of wireless devices and systems there have been and are concerns regarding their effects on the human body. Respective regulatory agencies have developed safety standards based on scientific research on electromagnetic (EM) exposure from wireless devices and antennas. The metric that quantifies the exposure level is called the Specific Absorption Rate (SAR). Wireless devices must satisfy the regulatory standards before being marketed. In the past, researchers have primarily focused on investigating the EM exposure from wireless devices that are used very near to the user's head or body (less than 25 mm). But as time progressed many more wireless devices have become ubiquitous (vehicular wireless devices, laptop PCMCIA cards, Bluetooth dongles, wireless LAN routers, cordless phone base stations, and pico base stations are to name a few) and are operated at distances greater than 25 mm yet smaller than 200 mm. Given the variations in operating frequency, distance, and antenna size and type it is challenging to develop an approach using which EM exposure from a wide variety of wireless devices can be evaluated. The problem becomes more involved owing to the difficulties in identifying the antenna zone boundaries, e.g. reactive near-field, radiating near-field, far-field etc. The focus of this thesis is to investigate a large class of low and highly directive antennas and evaluate the EM exposure from them into a large elliptical phantom. The objective is to be able to predict threshold power levels that meet the SAR limits imposed by the regulatory agencies. It was observed that among the low directivity antennas at close near-field distances, electrically small antennas induced distinguishably higher SAR than electrically larger antennas. But differences in SAR were small as the phantom moved into the far-fields of the antennas. SAR induced by highly directive antennas were higher when the phantom was in the far-field of the antennas and was facing the antenna frontal plane. The same was not true when the phantom was in the near-field of the antennas. Finally, by analyzing the simulation and measurement data threshold power formulas were developed for low directivity antennas using which power levels corresponding to the safe exposure limits independent of device type or geometry can be estimated.

Mazady, Md. Anas Boksh

178

Antennas for concealed weapon detection  

Microsoft Academic Search

Detection of concealed weapons is limited first by the signal to clutter ratio, and hence a trade between antenna beamwidth versus range to the suspect. An approach is described based on crossed focused line source antennas to produce a small common (transmit-receive) footprint on the subject being examined. These antenna beams can be phased, but a cost-effective approach is to

D. J. Kozakoff; V. Tripp

2005-01-01

179

Design of reconfigurable slot antennas  

Microsoft Academic Search

In this paper the design of a compact, efficient and electronically tunable antenna is presented. A single-fed resonant slot loaded with a series of PIN diode switches constitute the fundamental structure of the antenna. The antenna tuning is realized by changing its effective electrical length, which is controlled by the bias voltages of the solid state shunt switches along the

Dimitrios Peroulis; Kamal Sarabandi; Linda P. B. Katehi

2005-01-01

180

An active uplink photonic antenna  

Microsoft Academic Search

This paper presents a wideband photonic antenna consisting the laser diode, matching circuit, RF amplifier and microstrip patch antenna are fabricated and connected together to perform in uplink system. Laser driver is used to supply the dc biasing for the laser. Lastly, the LD-matching circuit, RF amplifier and antenna were arrange together and connected to perform the wireless uplink system.

N. F. Nanyan; S. Z. M. Hashim; R. Ngah; Y. Rahayu; T. Prakoso

2010-01-01

181

LF and VLF antenna modeling  

Microsoft Academic Search

The 60 kHz timing station in Fort Collins, Colorado known as WWVB and a 21.4 kHz Navy VLF transmit antenna at Lualualei, Hawaii were modeled using the method of moments wire modeling code, Expert MININEC Broadcast Professional. An accurate computational antenna model was needed in order to evaluate proposed antenna modifications. The evaluation criteria for defining an \\

D. E. Hurdsman; P. M. Hansen; J. W. Rockway

2003-01-01

182

Resonances of sandwiched optical antenna  

Microsoft Academic Search

We calculate the resonant properties of the sandwiched triangle and bowtie antennas using finite difference time domain technique and compare with one-layer structures. The sandwiched antennas possess two tunable resonances corresponding to the symmetric and antisymmetric modes for dipole excitation, which can be understood by the hybridization of the plasmons supported by the two golden layers of the antennas. We

Lisheng Wang; Jiasen Zhang; Xiaofei Wu; Jing Yang; Qihuang Gong

2008-01-01

183

A Simple, Efficient TV Antenna  

NSDL National Science Digital Library

This website, provided by Professor Rick Matthews of Wake Forest University, contains instructions on how to build an inexpensive but effective TV antenna. The site includes formulas for converting channel number to frequency, and frequency to wavelength (that is, wavelength in "twin-lead," the standard antenna lead wire). A diagram shows that the distance across antenna is half wavelength.

2007-05-03

184

Comparison between remote Antenna Units with Detachable antennas and Photonic Active Integrated Antennas for indoor applications  

Microsoft Academic Search

Measurements are presented for the performance evaluation of two distinct low cost and low power Radio over Fiber (RoF) architectures for indoor applications. One is a low power consumption component based remote antenna system - with detachable antennas and the second is a system which features Photonic Active Integrated Antennas with lossless matching circuits.

Philippos Assimakopoulos; Vitawat Sittakul; Anthony Nkansah; Nathan Gomes; Martin Cryan; David Wake

2011-01-01

185

Quartz antenna with hollow conductor  

DOEpatents

A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

Leung, Ka-Ngo (Hercules, CA); Benabou, Elie (Alameda, CA)

2002-01-01

186

Near-field testing of the 15-meter hoop-column antenna  

NASA Astrophysics Data System (ADS)

A 15-m-diameter antenna was tested to verify that dimensional tolerances for acceptable performance could be achieved and to verify structural, electromagnetic, and mechanical performance predictions. This antenna utilized the hoop column structure, a gold plated molybdenum mesh reflector, and 96 control cables to adjust the reflector conformance with a paraboloid. The dimensional conformance of the antenna structure and surface was measured with metric camera and theodolites. Near field pattern data were used to assess the electromagnetic performance at five frequencies from 2.225 to 11.6 GHz. The reflector surface was adjusted to greatly improve electromagnetic performance with a finite element model and the surface measurements. Measurement results show that antenna surface figure and adjustments and electromagnetic patterns agree well with predictions.

Schroeder, Lyle C.; Adams, Richard R.; Bailey, M. C.; Belvin, W. Keith; Butler, David H.; Campbell, Thomas G.

1989-08-01

187

Antenna Array Element Study.  

National Technical Information Service (NTIS)

An investigation and analytical study of antenna array elements is being carried out to determine the influence of an individual element of specific characteristics on the performance of an array and, on the basis of element performance, to present data w...

M. B. Haslam

1966-01-01

188

Compact antenna range  

Microsoft Academic Search

The applications of compact antenna range systems for indoor measurements under far-field conditions are discussed. Compact range systems are used to collimate the radiation from a point or a line source by means of a lens or parabolic reflector. Some technical consideration of compact range design are discussed, including: optimal stray radiation levels; shapes and dimensions of the plane wave

V. J. Vokurka

1983-01-01

189

Measurements column [antenna testing  

Microsoft Academic Search

The alignment of the mechanical axes of a compact range test positioner to the compact range wavefront is addressed. Reflection measurements are used to calibrate the range and to determine the gain of antennas. It is shown that the circular flat plate and the vertical wire are accurate electrical alignment tools for the field direction and the polarization vector. With

J. Hammer

1991-01-01

190

Steps towards photonic antennas  

Microsoft Academic Search

Summary form only given. Photonics are basically replacing conventional components, such as the coaxial lead that would have interconnected the antenna and electronics. In the replacement stage, the design of the electronics is largely, if not completely, unaffected by the photonics. A second step in the evolution, of which we are beginning to see signs already, is the integration of

2000-01-01

191

Multi-Purpose Antenna.  

National Technical Information Service (NTIS)

A description is given of a microwave antenna, useful on a spacecraft, which utilizes a single dish reflector and single coaxial horn structure to transmit at two frequencies, and to receive signals at a third frequency that allow tracking. The horn struc...

K. E. Woo

1970-01-01

192

Impulse radiating antennas  

Microsoft Academic Search

A number of applications require radiation of a short pulse of electromagnetic energy out to large distances. These applications include target discrimination in a cluttered environment (e.g., looking over the ocean), aircraft identification by taking a 'TDR' of its major scattering centers, and target location through foliage. The Impulse Radiating Antenna (IRA) has generated widespread interest for its ability to

Carl E. Baum; Everett G. Farr

1993-01-01

193

UHF fractal antennas  

Microsoft Academic Search

The use of fractal antenna techniques to reduce the size of a UHF linear dipole is investigated and discussed. Fractal designs are derived using an empirical method and a genetic algorithm based method. While both achieve size reduction, the latter design shows the most promise from a size reduction and design methodology standpoint, since simulation is inherent in the design

S. D. Eason; R. Libonati; J. W. Culver; D. H. Werner; P. L. Werner; S. Mummareddy

2001-01-01

194

Community Antenna Television (CATV).  

ERIC Educational Resources Information Center

|The number of households hooked up to cable television or community antenna television (CATV) is expanding rapidly, and Federal Communications Commission (FCC) has been developing regulations since 1962 to guide the growth of the industry. By 1965 the FCC had claimed jurisdiction over all CATV systems in the U. S. This jurisdiction was challenged…

Federal Communications Commission, Washington, DC.

195

Low Gain S-Band TT and C Antennas. Development of Cardioid Coverage Antenna.  

National Technical Information Service (NTIS)

Antenna designs are discussed for a cardioid shaped pattern providing sufficient coverage for the spacecraft telemetry/telecommand/ranging link. Two types of antenna are examined: wire-antenna array design and waveguide antenna design with conical reflect...

N. C. Albertsen P. Balling F. R. Gregersen F. Laursen

1976-01-01

196

Conformable seal  

DOEpatents

Sealing apparatus and method, comprising first and second surfaces or membranes, at least one of which surfaces is deformable, placed in proximity to one another. Urging means cause these surfaces to contact one another in a manner such that the deformable surface deforms to conform to the geometry of the other surface, thereby creating a seal. The seal is capable of undergoing multiple cycles of sealing and unsealing.

Neef, W.S.; Lambert, D.R.

1982-08-10

197

System design and performance of a wideband photonic array antenna  

Microsoft Academic Search

Presented in this paper is an overview of the development of a wideband photonic array antenna. The presentation will focus on the performance of a unique L-band 24 X 4 element conformal array, supported by a photonic true-time-delay beamforming network. A 2-ns pulse was injected into the system and the round trip impulse response was measured to demonstrate the array's

J. J. Lee; Stan Livingston; Robert Y. Loo; V. L. Jones; C. Foster; Huan-Wun Yen; Gregory L. Tangonan

1994-01-01

198

Wideband Planar Log-Periodic Antenna  

Microsoft Academic Search

A compact planar wideband microstrip antenna is introduced. The antenna is a log-periodic antenna with 7 dipole elements. The antenna is designed to function in the frequency range of 500 to 700 MHz. It has a dimension of 268 mm by 145 mm by 3 mm. The matching is better than -10 dB in the working bandwidth. The proposed antenna

M. M. Tajdini; M. Shahabadi

2007-01-01

199

Optical antennas for nano-photonic applications  

Microsoft Academic Search

Antenna-coupled optical detectors, also named optical antennas, are being developed and proposed as alternative detection devices for the millimetre, infrared, and visible spectra. Optical and infrared antennas represent a class of optical components that couple electromagnetic radiation in the visible and infrared wavelengths in the same way as radioelectric antennas do at the corresponding wavelengths. The size of optical antennas

Javier Alda; José M Rico-García; José M López-Alonso; G Boreman

2005-01-01

200

Printed Monopole Slot Antenna for Internal Multiband Mobile Phone Antenna  

Microsoft Academic Search

A new internal multiband mobile phone antenna formed by two printed monopole slots of different lengths cut at the edge of the system ground plane of the mobile phone is presented. The antenna can generate two wide bands centered at about 900 and 2100 MHz to cover the GSM850\\/GSM900\\/DCS\\/PCS\\/UMTS bands and the 2.4-GHz WLAN band. Further, the antenna has a

Chun-I. Lin; Kin-Lu Wong

2007-01-01

201

Microwave ablation coaxial antenna computational model slot antenna comparison  

Microsoft Academic Search

Microwave ablation computational model, on COMSOL Multiphysics 4.0a, was presented in this paper using two types of coaxial antenna, one-slot and two-slot antenna. Computational model was done using electric and thermal properties of healthy breast tissue and tumoral breast tissue. Maximum temperature reached with two-slot coaxial antenna on healthy breast tissue was 110 °C, and on tumoral breast tissue was

R. Ortega-Palacios; A. Vera; L. Leija

2012-01-01

202

Novel metamaterial based antennas for flexible wireless systems  

NASA Astrophysics Data System (ADS)

Recent years have witnessed a great deal of interest from both academia and industry in the field of flexible electronic systems. This research topic tops the pyramid of research priorities requested by many national research agencies. Consistently, flexible electronic systems require the integration of flexible antennas operating in specific frequency bands to provide wireless connectivity which is highly demanded by today's information oriented society. On the other hand, metamaterials have become very popular in the design of contemporary antenna and microwave devices due to their wide range of applications derived from their unique properties which significantly enhances the performance of antennas and RF systems. Accordingly, the integration of metamaterial structures within flexible wireless systems is very beneficial in this growing field of research. A systematic approach to the analysis and design of flexible and conformal antennas and metamaterials is ultimately needed. The research reported in this thesis focuses on developing flexible low profile antennas and metamaterial structures in addition to characterizing their performance when integrated within flexible wireless systems. Three flexible, compact, and extremely low profile (50.8 microm) antennas intended for WLAN, Bluetooth and Ultra Wide Band (UWB) applications are presented. Next, a novel miniaturized Artificial Magnetic Conductor (AMC) and a new technique to enhance the bandwidth of micro-Negative (MNG) metamaterial are reported. Furthermore, the effect of bending on the AMC and MNG metamaterial is investigated in this thesis for the first time. Finally, the findings of this research are utilized in practical applications with specific design constraints including mutual coupling reduction between radiating elements in antenna arrays and MIMO systems and Specific Absorption Rate (SAR) reduction in telemedicine systems.

Khaleel, Haider Raad

203

Microstrip antenna technology  

Microsoft Academic Search

Absfruct-A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant freqnency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and fmite-element

KEITH R. CARVER; J. Mink

1981-01-01

204

Wimpy Radar Antenna  

NSDL National Science Digital Library

Students reinforce an antenna tower made from foam insulation so that it can withstand a 480 N-cm bending moment (torque) and a 280 N-cm twisting moment (torque) with minimal deflection. During one class period, students discuss the problem, run the initial bending and torsion tests and graph the results. During the following class periods, students design, construct and test sturdier towers, and graph the results.

Center For Engineering Educational Outreach

205

LOFAR High Band Antenna  

NASA Astrophysics Data System (ADS)

The Low Frequency Array (LOFAR) will initiate a new era of astronomical discovery at the low frequency end of the electromagnetic spectrum by virtue of its large number of antennas ( 13,000 each in multiple frequency bands), large spatial extent ( 400 km), and wide frequency range (10-240 MHz). Each High Band Antenna, which covers 120-240 MHz, is an electronically steerable, compact array of 16 dual-polarization receptors. The starting point for the antenna design -- a 4x4 square array of inverted-vee dipole receptors -- is studied using both electromagnetic computer simulations and prototype field testing. Through analysis at selected frequencies, the effect of spacing on the severity of grating lobes and beam steering is determined. In computer simulation, the shape of the dipole receptor is adjusted in order to optimize performance and ease of manufacture, and a particular model is highlighted which provides an improved beamwidth and greater sensitivity across the band of operation. This work was funded by the REU program of the NSF.

Zimmerman, N.; Kratzenberg, E.; Corey, B.

2003-12-01

206

Efficient Placement of Directional Antennas  

SciTech Connect

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.

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

2010-09-20

207

Antenna structure with distributed strip  

SciTech Connect

An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

Rodenbeck, Christopher T. (Albuquerque, NM)

2008-10-21

208

Antenna structure with distributed strip  

SciTech Connect

An antenna comprises electrical conductors arranged to form a radiating element including a folded line configuration and a distributed strip configuration, where the radiating element is in proximity to a ground conductor. The folded line and the distributed strip can be electrically interconnected and substantially coplanar. The ground conductor can be spaced from, and coplanar to, the radiating element, or can alternatively lie in a plane set at an angle to the radiating element. Embodiments of the antenna include conductor patterns formed on a printed wiring board, having a ground plane, spacedly adjacent to and coplanar with the radiating element. Other embodiments of the antenna comprise a ground plane and radiating element on opposed sides of a printed wiring board. Other embodiments of the antenna comprise conductors that can be arranged as free standing "foils". Other embodiments include antennas that are encapsulated into a package containing the antenna.

Rodenbeck, Christopher T. (Albuquerque, NM)

2008-03-18

209

Unfurlable satellite antennas: A review  

Microsoft Academic Search

\\u000a Abstract  A review of unfurlable satellite antennas is presented. Typical application requirements for future space missions are first\\u000a outlined. Then, US and European mesh and inflatable antenna concepts are described. Precision deployables using rigid panels\\u000a or petals are not included in the survey.RF modelling and performance analysis of gored or faceted mesh reflector antennas are then reviewed. Finally, both on ground

Antoine G. Roederer; Yahia Rahmat-samii

1989-01-01

210

Dual-frequency patch antennas  

Microsoft Academic Search

Dual-frequency patch antennas may provide an alternative to large-bandwidth planar antennas, in applications in which large bandwidth is really needed for operating at two separate transmit-receive bands. When the two operating frequencies are far apart, a dual-frequency patch structure can be conceived to avoid the use of separate antennas. In this paper, a critical overview of possible solutions for dual-frequency

S. Maci; G. BifJi Gentili

1997-01-01

211

Inflatable antenna for cubesats: Motivation for development and antenna design  

NASA Astrophysics Data System (ADS)

CubeSats and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, moving from Low Earth Orbit (LEO) to Geostationary Earth Orbit (GEO) or further, the communication systems currently implemented will not be able to support those missions. One of the bottlenecks in small spacecraft communication systems is represented by antennas' size, due to the close relation between antenna gain and dimensions. Current antennas for CubeSats are mostly dipole or patch antennas with limited gain. Deployable (not inflatable) antennas for CubeSats are currently being investigated, but these solutions are affected by the challenge of packaging the whole deployable structure in a small spacecraft.The work that we propose represents the first attempt to develop an inflatable antenna for CubeSats. Inflatable structures and antennas can be packaged efficiently occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. Inflatable antennas have been previously tested in space (Inflatable Antenna Experiment, STS-77). However they have never been developed for small spacecraft such as CubeSats, where the packaging efficiency, the deployment, and the inflation represent a challenge.Our study explores for the first time the possibility of developing such antenna in a way compatible with CubeSat dimensions and constraints. The research provides answers on the possible dimensions for an inflatable antenna for small satellites, on the gain and resolution that can be achieved, and on the deployment and inflation mechanism compatible with CubeSat. Future work in the development of the antenna will include the test of the antenna in flight during a specific technical demonstration mission.The article is structured as follows: context and motivation for Cubesat inflatable antenna are described; then a study to design the antenna which achieves the required performance metrics, while respecting the constraints imposed by CubeSat structure, is presented.

Babuscia, Alessandra; Corbin, Benjamin; Knapp, Mary; Jensen-Clem, Rebecca; Van de Loo, Mark; Seager, Sara

2013-10-01

212

An Antenna with Inherent Filtering Action.  

National Technical Information Service (NTIS)

The patent application describes an antenna which provides inherent filtering action by which the frequency response curve of the antenna can be shaped. In the preferred inventive embodiment, the antenna comprises at least one elongated receiving element,...

T. M. Babij R. R. Bowman P. F. Wacker

1975-01-01

213

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2012 CFR

...859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height necessary to assure adequate service. Certain CTS antennas must be individually licensed to the 218-219 MHz System...

2012-10-01

214

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2011 CFR

...859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height necessary to assure adequate service. Certain CTS antennas must be individually licensed to the 218-219 MHz System...

2011-10-01

215

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2012 CFR

...erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a single-wire transmitting antenna of the same length and must also include suitable...

2012-10-01

216

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2011 CFR

...erection must be provided. If the installed transmitting antenna is suspended between supports, this spare antenna must be a single-wire transmitting antenna of the same length and must also include suitable...

2011-10-01

217

Performance Analysis of High Resolution DOA Estimation for Conical Conformal Array  

Microsoft Academic Search

Classical high resolution DOA estimation methods such as MUSIC (multiple signal classification), ML (maximum likelihood) and WSF (weighted subspace fitting) are replanted into conformal array antennas by modeling conical conformal manifold in this paper. The variance of these algorithms mentioned above and CRB (Cramer-Rao bound) are given. The performances and their relationship among these methods are compared and the effects

De-Yuan Gao; Zi-Sen Qi; Bu-Hong Wang; Ying Guo

2008-01-01

218

Antenna applications of non-Foster elements  

Microsoft Academic Search

Three different antenna applications of non-Foster elements in resonant antennas, leaky-wave antennas and series-fed antenna arrays, are investigated. A resonant antenna is presented in which an internal tuning element is replaced with a combination of non-Foster elements in order to make the antenna wideband. Moreover, a non-dispersive fast-wave transmission line, which can be obtained by loading a host transmission line

Hassan Mirzaei; George V. Eleftheriades

2012-01-01

219

Aerotransported radar antenna for oil spills monitoring antennas and propagation  

Microsoft Academic Search

This work presents an antenna array design for monitoring oil spills on ocean surface operating within X-band. Its feed system comprises coupling slots and metallic coupling tuning ridges designed to individually control the signal amplitude of each antenna module and form the squared cosecant profile. The tuning ridges introduce two degrees of freedom to control the amplitude in each module.

A. M. P. Alves; D. N. Duplat; L. P. de Oliveira; H. E. Hernandez-Figueroa

2010-01-01

220

Impedance of patch antenna for active antenna's structures  

Microsoft Academic Search

The paper describes a method for varying the impedance of patch antennas. With this method, both the phase and magnitude of the impedance can be varied in a wide range of different values. This gives us the possibility of integrating an antenna with a variety of different active microwave semiconductors. First we describe the method and its characteristics, such as

D. Radulovic; A. Nesic; I. Radnovic

2004-01-01

221

Proceedings of the 2001 Antenna Applications Symposium. Volume 2.  

National Technical Information Service (NTIS)

The proceedings of the 2001 Antenna Applications Symposium is a collection of state-of-the-art papers relating to phased array antennas, Reconfigurable Antennas, Microstrip Antennas, Fractal Antennas.

D. H. Schaubert

2002-01-01

222

Proceedings of the 2001 Antenna Applications Symposium. Volume 1.  

National Technical Information Service (NTIS)

The proceedings of the 2001 Antenna Applications Symposium is a collection of state-of-the-art papers relating to phased array antennas, Reconfigurable Antennas, Microstrip Antennas, Fractal Antennas.

D. H. Schaubert

2002-01-01

223

Antennas - Our electronic eyes and ears  

NASA Astrophysics Data System (ADS)

Although the number of antenna types is vast, all antenna properties may be characterized in terms of the same basic parameters of radiation pattern, impedance, radar cross-section, and temperature. A comprehensive introduction is presented to antenna configurations; these encompass, among antennas constructed of wire or tubing, such wideband and circularly polarized types as helices, linear conductors, and loops. Sheet-conductor antenna families include reflectors, waveguides, and slotted antennas. Nonconducting dielectric antennas are lenses, polyrods, and slabs. Antenna array types range over 'driven', parasitic, and adaptive configurations. 'Two half-wavelength' and 'four half-wavelength' element arrays are also discussed.

Kraus, John D.

1989-01-01

224

Antenna Technology Shuttle Experiment (ATSE)  

Microsoft Academic Search

Numerous space applications of the future will require mesh deployable antennas of 15 m in diameter or greater for frequencies up to 20 GHz. These applications include mobile communications satellites, orbiting very long baseline interferometry (VLBI) astrophysics missions, and Earth remote sensing missions. A Lockheed wrap rip antennas was used as the test article. The experiments covered a broad range

R. E. Freeland; E. Mettler; L. J. Miller; Y. Rahmet-Samii; W. J. Weber III

1987-01-01

225

Antenna surface contour control system  

Microsoft Academic Search

The invention is a system for automatically controlling the surface contour of a deployable and restowable antenna having a mesh reflector surface supported by a circular, folding hoop affixed to a central, telescoping column. The antenna, when deployed, forms a quad-aperture reflector with each quadrant of the mesh surface shaped to provide an offset parabolic radio frequency (RF) reflector. The

Elvin L. Ahl; James B. Miller

1989-01-01

226

Very broadband loaded monopole antennas  

Microsoft Academic Search

A novel antenna design method is proposed and applied to overcome the narrowband characteristics of the monopole antenna by loading it with lumped elements. A genetic algorithm based optimization technique is used to determine the load values, their respective locations and the matching network elements. A bandwidth ratio of 20:1 within the frequency range of 23-460 MHz is achieved with

Korkut Yegin; Anthony Q. Martin

1997-01-01

227

Dynamic Flaps Electronic Scan Antenna.  

National Technical Information Service (NTIS)

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. The plasma introduces a hysteresis property to the pha...

D. G. Gonzalez

2000-01-01

228

Supergain antennas: possibilities and problems  

Microsoft Academic Search

In principle, any desired amount of gain can be developed from an antenna of arbitrary size. The phenomena of high gain from very small antennas is called “supergain”. To see why this statement might be so, the author recalls the construction used in optics, known as Huygens' principle. This states that every point on a wavefront can be regarded as

R. P. Haviland

1995-01-01

229

Smart-skin antenna technology  

Microsoft Academic Search

Using smart materials and skins, one could design a smart structure with suitable feedback system architecture. This paper is designed to address some technical advances and applications of smart materials, smart skins and coatings covering a broad spectrum of electromagnetic fields. The Smart Skin Antenna Technology Program's objectives are to (1) use smart skin technologies to develop an antenna system

Vijay K. Varadan; Vasundara V. Varadan

1993-01-01

230

DUALBAND WEARABLE UHF RFID ANTENNA  

Microsoft Academic Search

Based on a system study of the ability to use a commercial RFID system operating in 869 MHz band for the identification of moving sportsmen (1), TAG antennas has been recognized as one of the most sensitive component that affect the proper function of the whole system, especially in case when TAG antenna has to operate in the close vicinity

Milan Svanda; Milan Polivka

231

ANTENNA VIBRATION MEASUREMENTS WITH ACCELEROMETERS  

Microsoft Academic Search

We have made experiments on a 10-m antenna with accelerometers and angle encoders under a windy condition to diagnose motions of antenna structure. Power spectrum densities of acceleration obtained with the two instruments were consistent in a frequency range from 1 Hz to 10 Hz, but have a large discrepancy below 1 Hz due to noise in the accelerometers. A

Nobuharu. Ukita; Masafumi Ikeda

232

New type of turnstile antenna  

Microsoft Academic Search

The paper presents a new type of turnstile antenna realized with two crossed dipoles parallelly connected. Feeding of the dipoles in phase quadrature to obtain omnidirectional radiation pattern is achieved by optimizing their impedances to be complex-conjugated. Dipoles are realized with aluminum strips. Balun - transition from the antenna to coaxial cable - is accomplished with concentrated parameters - two

Ivana Radnovi?; A. Necic

2009-01-01

233

Graphene-antenna sandwich photodetector.  

PubMed

Nanoscale antennas sandwiched between two graphene monolayers yield a photodetector that efficiently converts visible and near-infrared photons into electrons with an 800% enhancement of the photocurrent relative to the antennaless graphene device. The antenna contributes to the photocurrent in two ways: by the transfer of hot electrons generated in the antenna structure upon plasmon decay, as well as by direct plasmon-enhanced excitation of intrinsic graphene electrons due to the antenna near field. This results in a graphene-based photodetector achieving up to 20% internal quantum efficiency in the visible and near-infrared regions of the spectrum. This device can serve as a model for merging the light-harvesting characteristics of optical frequency antennas with the highly attractive transport properties of graphene in new optoelectronic devices. PMID:22703522

Fang, Zheyu; Liu, Zheng; Wang, Yumin; Ajayan, Pulickel M; Nordlander, Peter; Halas, Naomi J

2012-06-19

234

DEA deformed stretchable patch antenna  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

235

Plasmonic dipole antennas on silicon  

NASA Astrophysics Data System (ADS)

Metallic nanowires of rectangular cross-section can operate as isolated or arrayed optical monopole or dipole antennas, and when deposited on a Si substrate and covered with water, become useful as (bio)chemical sensors. The optical performance of such antennas is assessed over a broad wavelength range as a function of geometrical parameters, including wire thickness, width, length, and gap (in the case of dipoles). Effects caused by varying the pitch of twodimensional arrays of antennas are also determined. Given a uniform broadside excitation, antennas resonate in the main mode of propagation of the corresponding asymmetric metal stripe waveguide, and antennas performance is related to its propagation characteristics. The structures considered are amenable to fabrication via metal evaporation and lift-off, with the nanowires defined by electron beam patterning.

Siadat Mousavi, Saba; Alavirad, Mohammad; McNamara, Derek; Roy, Langis; Berini, Pierre

2012-10-01

236

Time-domain three antenna method for evaluation of antenna factors of log-periodic antenna  

Microsoft Academic Search

we have proposed the method for evaluating the free- space antenna factor of a log-periodic broadband antenna (LPDA) with time-domain technique [1]. Our method is based on the techniques of time domain analysis and pulse compression technology. The introduced function enables us to isolate the direct wave from the reflected waves on the ground plane in an open area test

Satoru Kurokawa; Masanobu Hirose; Koji Komiyama

2007-01-01

237

Impact of antenna directivity for carrier sensing in high density WLAN using adaptive directional antenna  

Microsoft Academic Search

This paper describes impact of antenna directivity for carrier sensing on system throughput in high density wireless LAN (WLAN) using adaptive directional antenna. Adaptive directional antenna is effective to improve system throughput of WLAN, however it is necessary to clear the impact of antenna directivity used for carrier sensing in CSMA based WLAN since directional antenna may increase packet collisions

Masahiro UMEHIRA; Yohei OHTOMO

2010-01-01

238

UHF RFID Tag Antenna Design and a Novel Antenna Verification Development Platform  

Microsoft Academic Search

This paper mainly designs an UHF RFID tag antenna, and also develops a novel UHF RFID tag antenna verification development platform, that are compatible with ISO\\/IEC 18000- 6B Standard, operating at the 915 MHz. The new folded RFID tag antenna is designed to reduce the length of the antenna's arms, stretch antenna's working band width and be able to adjust

Luhong Mao; Ruiliang Song; Yanming Li; Liying Chen

2008-01-01

239

UWB Vivaldi antenna for impulse radio beamforming  

Microsoft Academic Search

In this paper, two different types of Vivaldi antenna are designed and tested suitable for electromagnetic beamforming. The first is an antipodal Vivaldi antenna, while the other is a tapered slot Vivaldi antenna. They are both ultra wideband antennas for the 1 GHz to 5 GHz frequency band. They have low impulse distortion and the voltage standing wave ratio (VSWR)

Tuan Anh Vu; Malihe Zarre Dooghabadi; Shanthi Sudalaiyandi; H. A. Hjortland; O. Naess; Tor Sverre Lande; S. E. Hamran

2009-01-01

240

Decoupling and descattering networks for antennas  

Microsoft Academic Search

The possibilities of connecting a lossless network between input ports and antenna ports such that there is no coupling and scattering between the antennas are discussed. A necessary condition for complete decoupling and descattering is power orthogonality between the patterns of the individual antennas. Numerical and experimental results are presented for monopole antennas.

J. BACH ANDERSEN; HENRIK HASS RASMUSSEN

1976-01-01

241

Folded dipole antenna near metal plate  

Microsoft Academic Search

The paper presents the effects on antenna parameters when an antenna is placed horizontally near a metal plate. The plate has finite size and rectangular shape. A folded dipole antenna is used and it is placed symmetrically above the plate. The FEM (finite element method) is used to simulate the dependency of antenna parameters on the size of the plate

P. Raumonen; L. Sydanheimo; L. Ukkonen; M. Keskilammi; M. Kivikoski

2003-01-01

242

Ultra-broadband Photonic Patch Antenna  

Microsoft Academic Search

This paper presents a demonstration an ultra-broadband photonic antenna. The antenna utilizes external optical intensity modulators and optic fiber to photonically remotes the aperture stacked patch antennas and replaces microwave diplexers with simple photonic combination. The resulting photonic antenna is demonstrated to provide a bandwidth of 110% with gain of 7 dBi

E. R. Lopez; L. A. Bui; K. Ghorbani; W. S. T. Rowe; A. Mitchell

2006-01-01

243

Advanced antenna technologies for satellite communication payloads  

Microsoft Academic Search

This paper addresses some of the recent developments at LMCSS in the area of multiple beam and reconfigurable beam antennas for communication satellite payloads. These advancements include (a) multiple aperture dual-band reflector antennas, (b) high efficiency horns covering 50% bandwidth, (c) a novel ?stepped-reflector antenna? (SRA) technology, and (d) reconfigurable beam antennas for HIEO and GEO satellites. It is shown

Sudhakar Rao; Minh Tang; Chih-Chien Hsu; Jim Wang

2006-01-01

244

The smart antenna module for RF repeater  

Microsoft Academic Search

The signals received at the receiving antenna are consist of signals from base station (or mobile terminal) and transmitted signals from the other side of antenna in a RF repeater. And the amplification rate of the RF repeater is limited by the feedbacked signals from the same repeater. Therefore, a receiving antenna has to be isolated from a transmitting antenna

Seong-Goo Lee; Tae-Seok Lee; Min-Sang Kim; Dae-Young Cho; Yong-Hyun Seo; Kil-Yung Kim; Dae-Gun Cho; Se-in Park; Hak-Lim Ko

2011-01-01

245

Antenna development for astroparticle and radioastronomy experiments  

Microsoft Academic Search

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

Didier Charrier

246

Broad-band gap coupled microstrip antenna  

Microsoft Academic Search

A microstrip antenna with large bandwidth is developed using a parasitic technique. Compared to the available wideband antennas, the proposed antenna structure is very compact and gives a less distorted radiation pattern with frequency. An impedance bandwidth eight times that of a conventional patch antenna of the same size is achieved. The concept of coupled microstrip line model is extended

C. K. Aanandan; P. Mohanan; K. G. Nair

1990-01-01

247

High temperature permittivity measurements of Alumina Enhanced Thermal Barrier (AETB-8) material for CEV antenna radomes  

Microsoft Academic Search

Alumina Enhanced Thermal Barrier (AEBT-8) material is currently being considered as a potential radome material for phased array antennas that will be conformally mounted to the outer surface of NASA's Orion Crew Exploration Vehicle. Accordingly, there is a need to establish if the dielectric properties of the AEBT-8 material change as a function of temperature. In this paper we discuss

C. H. Mueller; F. A. Miranda

2010-01-01

248

Performance of Beverage antennas at low angles  

SciTech Connect

Numerical modeling of Beverage and monopole antennas shows the fields of both antennas to have a similar dependence on range and height above ground, with the Beverage antenna having slightly greater gain in the forward direction due to its directivity. The use of multiple Beverage antennas closely spaced was found to increase the efficiency and gain in the forward direction for short Beverage antennas. For the longer antenna considered for the HF bistatic radar, the decrease in directivity for two closely spaced antennas reduced the forward gain.

Burke, G.J.; King, R.J.; Lytle, R.J.; Miller, E.K.

1983-11-01

249

Vehicle antennas for mobile satellite communications  

NASA Astrophysics Data System (ADS)

Research on and the state of the art of vehicle antennas for mobile satellite communications are reviewed. Particular attention is given to the concept of mobile satellite communication; system requirements for vehicle antennas; antenna systems for communications, navigation, and broadcasting; and future prospects of vehicle antennas. A monolithic microwave integrated circuit active phased array antenna is considered to be a key technology in the future mobile satellite communications.

Ohmori, Shingo

1991-10-01

250

Cobwebb Antennas Applied on HF Communications  

Microsoft Academic Search

In order to build Timely and effective communication in HF blind-spot (20-100KM), Cobwebb folded dipole antenna was designed as well as matching circuitry. In this paper, antenna structure and antenna electric-height are simulated and amended in the use of electromagnetic simulation software FEKO. Antenna radiation patterns in the different electric-height are given. It is clear that the proper electrical antenna

D. B. Zhang; Z. L. Deng; J.-M. Huang

2010-01-01

251

The submarine-towed ELF loop antenna  

Microsoft Academic Search

To obtain omnidirectional reception, a solenoidal loop antenna can be built into the same cable as that used for the ELF electrode-pair antenna. The 1oop's noise voltage is higher in level and is more complex than that of the electrode-pair antenna. Measurements of towed cable vibration, of towed antenna noise, and of the physical and electrical properties of antenna cable

M. L. Burrows

1976-01-01

252

On the spaced antenna and imaging Doppler interferometer techniques  

NASA Astrophysics Data System (ADS)

The theory developed by Briggs (1995) is extended to explain the measurement of a wind velocity equivalent to the spaced antenna apparent wind by imaging Doppler interferometer-like (IDI-like) interferometric analyses. The point is made that the presence of turbulence, or random change in the diffraction pattern on the ground, is directly responsible for the difference between the true and apparent velocities in the spaced antenna analysis, and also for the overestimation of the wind velocity by the IDI technique. An experiment is conducted to determine whether the "effective" scattering points resolved by IDI-like analyses tend to lie upon the azimuth predicted by theory. This is found to be the case, even for unsmoothed cross spectra for which the theory was not explicitly derived. An averaging mechanism is proposed which may explain the extent to which the unsmoothed experimental data conform to the behavior predicted by theory.

Vandepeer, Brenton G. W.; Reid, Iain M.

1995-07-01

253

Antenna Technology Shuttle Experiment (ATSE).  

National Technical Information Service (NTIS)

Numerous space applications of the future will require mesh deployable antennas of 15 m in diameter or greater for frequencies up to 20 GHz. These applications include mobile communications satellites, orbiting very long baseline interferometry (VLBI) ast...

R. E. Freeland E. Mettler L. J. Miller Y. Rahmet-samii W. J. Weber

1987-01-01

254

The Intelsat VI antenna system  

NASA Astrophysics Data System (ADS)

This paper describes the antenna system design, implementation, and measurement program for the Intelsat VI spacecraft, which is the largest commercial communications satellite currently in orbit. Following a description of the complete antenna farm, detailed design tradeoffs and construction techniques for the hemi/zone antennas are presented. The discussion focuses on the interaction of the stringent spatial isolation, cross-polarization isolation, and pointing requirements. The extensive Intelsat VI antenna measurement program is also described, including alignment, feed array measurement in a near-field chamber over temperature, reflector distortion over temperature, far-field range testing, system-level and spacecraft measurement in a planar near-field chamber, and in-orbit measurements.

Persinger, Randy R.; Lane, Steven O.; Caulfield, Michael F.; Zaghloul, Amir I.

255

Improved HF Manpack Antenna Systems.  

National Technical Information Service (NTIS)

The report describes the engineering changes made to a family of lightweight HF antennas (see AD-842 443). It also provides the acceptance tests, maintainability analysis, reliability analysis, and reliability demonstration tests which were performed. (Au...

R. A. Kneblik R. L. Bell

1970-01-01

256

Compensation of finger effect on a mobile terminal antenna by antenna selection  

Microsoft Academic Search

In this paper, compensation of the effect of the user's finger on the operation of a mobile terminal antenna is studied, using antenna selection as the compensation method. A dual-element antenna is compared with a single-element antenna occupying the same total antenna volume. The results show that antenna selection can provide an improvement of at least 2 dB in total

R. Valkonen; S. Myllymaki; A. Huttunen; J. Holopainen; J. Ilvonen; P. Vainikainen; H. Jantunen

2010-01-01

257

Box truss antenna technology status  

NASA Astrophysics Data System (ADS)

Recent technology development activities for box truss structures and box truss antennas are summarized. Three primary activities are discussed: the development of an integrated analysis system for box truss mesh antennae; dynamic testing to characterize the effect of joint free play on the dynamic behavior of box truss structures; and fabrication of a 4.5 meter diameter offset fed mesh reflector integrated to an all graphite epoxy box truss cube.

Coyner, J. V.; Bachtell, E. E.

1986-11-01

258

Field Computations of Optical Antennas  

Microsoft Academic Search

Antenna-based near-field optical microscopy and spectroscopy makes use of locally enhanced opti- cal fields created near laser-irradiated metal nanostructures acting as local probes. Using three- dimensional simulations based on the finite element method we study the electromagnetic fields near various optical antennas and we optimize their geometry in order to bring out a strong enhance- ment in a selected frequency

Roman Kappeler; Daniel Erni; Cui Xudong; Lukas Novotny

259

Antennas for mobile satellite communications  

NASA Astrophysics Data System (ADS)

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.

Huang, John

1991-12-01

260

Electromagnetic antenna modeling (EAM) system  

NASA Astrophysics Data System (ADS)

The determination of foreign communications capabilities and intent is an important assessment function performed by the USAF National Air Intelligence Center (NAIC). In this context, Rome Laboratory became the NAIC engineering agent for the development of an NAIC requirement for the rapid analysis and evaluation of antenna structures based on often vague to sometimes detailed dimensional information. To this end, the Rome Laboratory sponsored development of the Electromagnetic Antenna Modeling (EAM) System, a state-of-the-art Pascal program with an MS Windows graphical user interface (GUI) pre- and post-processor. Users of NAIC capabilities initiate antenna analysis efforts that range from simple parametric studies to more complex, detailed antenna design and communication-system evaluations. Accordingly, EAM provides a modeling capability 'matched' to the sophistication of the individual analyst, with features appropriate for users ranging from nontechnical analysts to experienced antenna engineers. This capability is particularly valuable in the military-intelligence environment, in which high-speed assessments are required. In particular, EAM meets the specific antenna-analysis requirements of NAIC with a versatile graphical user interface.

Packer, Malcolm; Powers, Robert; Tsitsopoulos, Paul

1994-12-01

261

Reference Design of ICRF Antenna for EAST  

NASA Astrophysics Data System (ADS)

An antenna array suitable for plasma heating and current drive has been designed for the ion cyclotron resonance frequency range (ICRF) heating on the EAST superconducting tokamak. The ICRF heating is planned to operate in a frequency range of 30 MHz to 80 MHz and hence the antenna geometry is optimized for 55 MHz. The design is based on the conventional strap antenna element. The coupling properties of the antenna are calculated with a slab model of the plasma for the antenna simulation. The coupling code is extended for the analysis of the toroidal antenna array separated by septa.

Qin, Chengming; Zhao, Yanping; Hiroyuki, Okada; Zhang, Xinjun; Mao, Yuzhou; T, Watari; R, Kumazawa; T, Seki

2006-05-01

262

Spatial and temporal communication theory using adaptive antenna array  

Microsoft Academic Search

An adaptive antenna array or a smart antenna is named a software antenna because it can form a desired antenna pattern and adaptively control it if an appropriate set of antenna weights is provided and updated in software. It can be a typical tool for realizing a software radio. An adaptive antenna array can be considered an adaptive filter in

R. Kohno

1998-01-01

263

Characteristics of Airplane Antennas for Radio Range Beacon Reception  

Microsoft Academic Search

This paper gives the results of an investigation on the characteristics of airplane receiving antennas to determine whether an antenna arrangement could be devised which would have all the desirable electrical properties of the vertical pole antenna and yet be free from the mechanical difficulties encountered in the use of the pole antenna. The antennas studied include the inclined antenna

H. Diamond; G. L. Davies

1932-01-01

264

Optimal antenna placement in multi-hop wireless networks with heterogeneous antennas  

Microsoft Academic Search

The recent advances in antenna technology have made smart beamforming antennas attractive candidates to be deployed in multi-hop wireless networks. Beamforming antennas can increase the spatial reuse of the channel and consequently the network capacity. Due to practical and economical consid- erations, deploying beamforming antennas in the whole network is sometimes infeasible. In this paper, we focus on multi-hop wireless

Osama Bazan; Muhammad Jaseemuddin

2011-01-01

265

The compact antenna range for experimental improvement of space vehicles antennas  

NASA Astrophysics Data System (ADS)

We present estimates for some characteristics of a new compact antenna range for the experimental improvement and performance of tests of antennas of microwave range. The method of wave optics in view of the theory of Fresnel's diffraction was used to determine one of the main parameters of compact antenna measurement range, namely, the distance between a collimation mirror and tested antenna.

Ovsyanikov, V. V.; Popel', V. M.; Ol'Shevskiy, A. L.; Popel', P. V.

266

Direct Measurements of Stationary Antennas on a Compact Antenna Test Range  

Microsoft Academic Search

The work under review concerns a new technique for the measurement of the radiation behaviour of reflector antennas under the restriction that the antenna itself is not rotated during the measurement. This condition exists for example with space-qualified antennas that are often very fragile and that would deform when rotated. Instead of rotating the antenna, the Compact Range feed is

H. F. Schluper

1985-01-01

267

Phased Array Antenna for Space Shuttle Orbiter.  

National Technical Information Service (NTIS)

The National Aeronautics and Space Administration is developing a distributed phased array antenna at the Lyndon B. Johnson Space Center as a possible upgrade for the Space Shuttle Orbiter S-band phase modulation communications system. The antenna consist...

S. E. Davidson

1987-01-01

268

Mechanisms of the Rosetta high gain antenna  

NASA Astrophysics Data System (ADS)

This paper describes the antenna pointing mechanism (APM) and the hold down and release mechanism (HRM) used in the high gain antenna of the ROSETTA mission. The hold down and release mechanism consists of three units which compensate the tolerance mismatch between antenna and spacecraft through incorporation of potting rings. Given that the activation mode is pyrotechnic, release shock is a major concern and is minimised through integration of shock absorbers which allow stroking of the separation nuts. The antenna pointing mechanism is a dual drive (azimuth over elevation) unit which allows controlled rotation of the antenna. The drive units incorporate spring loaded end stops to prevent the antenna from hitting the spacecraft, and optical encoders which register the absolute position of the antenna. The pointing and the hold down mechanisms of the ROSETTA antenna are fully qualified and will withstand the high launch loads of the Ariane-5 and the environmental demands of deep space operation.

Pereira, Carlos

2001-09-01

269

Study of a VLF Distributed Antenna Array.  

National Technical Information Service (NTIS)

This study considers the use of an array of VLF antennas distributed throughout the UK, instead of a single, high powered antenna, for submarine command broadcasts. Such an array offers survivability and environmental advantages. The coverage of the array...

G. A. Ashdown

1993-01-01

270

Combination Antenna Receive-Transmit System (CARTS).  

National Technical Information Service (NTIS)

A system that allows simultaneous transmission and reception on a common antenna is designed. A simple decoupling network that provides decoupling from a transmitting antenna nearly independent of transmitter-multicoupler off-resonance impedance is design...

I. C. Olson

1970-01-01

271

Near-field testing of radar antennas  

NASA Astrophysics Data System (ADS)

The near-field technique is presented for pattern and gain testing of high-performance radar antennas. Near-field antenna pattern and gain measurement ranges produce a free-space port plane wave through superposition and synthesis. The field radiated by an antenna can be determined anywhere in free space from a set of measurements made on a planar, cylindrical, or spherical near-field measurement surface. The far-field radiation pattern and gain of the antenna may be determined, as well as the radiating component of the field at the aperture of the antenna. The amplitude, phase, and polarization accuracy of the synthesized plane wave is typically better than can be achieved in far-field or compact antenna measurement ranges. The aperture field can be used to phase align phased-array antennas, locate defects in radomes, and determine the surface shape of reflector antennas.

Joy, Edward B.

1990-01-01

272

Multiband small zeroth-order metamaterial antenna  

NASA Astrophysics Data System (ADS)

A novel resonant metamaterial antenna based on the Composite Right/Left-Handed (CRLH) transmission line (TL) model is presented. The proposed small antenna is designed to operate simultaneously over multiple wireless services (UMTS-WLAN-WIMAX)

Dakhli, Nabil; Choubani, Fethi; David, Jacques

2011-06-01

273

Antenna using a Photonic Bandgap Structure.  

National Technical Information Service (NTIS)

A microstrip patch antenna utilizes a microstrip patch antenna substrate formed of photonic bandgap material. One or more periodic patterns may be used therewith to produce multiple bandgaps into the photonic bandgap material. The periodic patterns may be...

J. A. LaComb

2006-01-01

274

Analysis of High Precision Composite Sandwich Antennas.  

National Technical Information Service (NTIS)

A data base for all common types of spacecraft antenna skin and core materials was established. Based on these material properties, it is possible to predict accurately the performance of high precision antennas, and there is good agreement between analys...

G. Helwig

1986-01-01

275

Integrated resonant tunneling diode based antenna  

DOEpatents

An antenna comprising a plurality of negative resistance devices and a method for making same comprising employing a removable standoff layer to form the gap between the microstrip antenna metal and the bottom contact layer.

Hietala, Vincent M. (Placitas, NM); Tiggers, Chris P. (Albuquerque, NM); Plut, Thomas A. (Albuquerque, NM)

2000-01-01

276

47 CFR 95.1213 - Antennas.  

Code of Federal Regulations, 2011 CFR

... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Medical Device Radiocommunication Service (MedRadio) § 95.1213 Antennas. No antenna for a MedRadio transmitter shall...

2011-10-01

277

Anti-Skywave AM Broadcast Antenna Design.  

National Technical Information Service (NTIS)

This thesis investigates the design of an anti-skywave (ASW) AM broadcast antenna. The parameters of a typical AM broadcast antenna are presented first. Then the design proposed is studied by numerical modeling with the Numerical Electromagnetic Code (NEC...

S. Hussain

1987-01-01

278

Modelling UHF Antenna Coupling on Aircraft.  

National Technical Information Service (NTIS)

Antenna coupling is of particular interest on aircraft where the structure interacts with the antenna arrays. These arrays may be extremely complex as new electronic countermeasures and signal intelligence systems are added to aircraft. The thesis attempt...

R. E. Koehler

1975-01-01

279

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2011 CFR

... (b) Directional antenna. No application for a construction permit of a new station, or change in channel, or change in an existing facility on the same channel will be accepted for filing if a directional antenna with a...

2011-10-01

280

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2012 CFR

... (b) Directional antenna. No application for a construction permit of a new station, or change in channel, or change in an existing facility on the same channel will be accepted for filing if a directional antenna with a...

2012-10-01

281

MARDS Antenna Design for Seismic Detection Systems.  

National Technical Information Service (NTIS)

A theoretical and experimental program has been conducted to determine an optimal antenna design for use with the MARDS (Medium Artillery Delivered Sensors) seismic detection system. Several models of MARDS antennas (vertically polarized) were evaluated o...

F. Reggia

1972-01-01

282

Photonic antenna reconfiguration: a status survey  

NASA Astrophysics Data System (ADS)

The primary focus of photonics for antenna systems has, historically, been on the development of link and beam steering techniques. More recent work is focusing on the design of new types of antenna elements or arrays of elements to take advantage of the advantages in photonics. By using photonically controlled devices and materials and materials it is possible to produce revolutionary changes in antenna elements and in the design and properties of arrays, opening the door for a new class of antennas - photonically controlled reconfigurable antennas. In this paper we survey the history and current status of photonically reconfigurable antennas. This will include the evolution of photonically controlled switches for application in antennas. We look at photonic control of reactive devices and the optically variable capacitor and the evolution of this device towards monolithic integration. Finally, we also will look at the state of photonically reconfigurable silicon and its application to antenna design.

van Blaricum, Michael L.

1998-11-01

283

Lower Hybrid Antenna Design for MST  

Microsoft Academic Search

Inter-digital line antennas are being used to test the feasibility of lower hybrid current drive in MST. The antennas use lambda\\/4 resonators and launch slow waves at 800 MHz with n|| ~ 7.5. Routine operation has been achieved with a good impedance match between antenna and plasma. High power antenna design improvements include larger vacuum feed-throughs, better impedance matching, and

J. A. Goetz; M. A. Thomas; M. C. Kaufman; S. P. Oliva

2005-01-01

284

Lower Hybrid Antenna Design for MST  

Microsoft Academic Search

Inter-digital line antennas are being used to test the feasibility of lower hybrid current drive in MST. The antennas use ?\\/4 resonators and launch slow waves at 800 MHz with n∥ ? 7.5. Routine operation has been achieved with a good impedance match between antenna and plasma. High power antenna design improvements include larger vacuum feed-throughs, better impedance matching, and

J. A. Goetz; M. A. Thomas; M. C. Kaufman; S. P. Oliva

2005-01-01

285

WIDEBAND STAR-SHAPED MICROSTRIP PATCH ANTENNA  

Microsoft Academic Search

Abstract—A new wideband and small size star shaped patch antenna fed capacitively by a small diamond,shape patch is proposed.To enhance the impedance bandwidth, posts are incorporated under the patch antenna.HFSS high frequency simulator is employed to analyze the proposed antenna and simulated results on the return loss, the E- and H-plane radiation patterns and Gain of the proposed antenna are

M. Abbaspour; Hamid Reza Hassani

2008-01-01

286

A fractal circular polarized RFID tag antenna  

NASA Astrophysics Data System (ADS)

In this paper, we present a novel fractal antenna for radiofrequency identification (RFID) tags. The proposed antenna has a resonant frequency equal to 2.45GHz and circular polarization. The fractal technique was very useful to obtain a miniaturization of antenna size by more than 30%. The gain and directivity of the antenna are acceptable for the desired RFID application. All the results are obtained using CST Microwave simulation tool.

Chaouki, Guesmi; Ferchichi, Abdelhak; Gharsallah, Ali

2013-09-01

287

Integrated micromachined millimeter wave patch antenna  

Microsoft Academic Search

We have proposed 3-D micromachined elevated patch antenna for G-band (140 GHz to 220 GHz) applications. The antenna is consisted of coplanar waveguide (CPW) feed line, a feeding post, air-bridge, supporting posts, and elevated patch. The antenna topology effectively creates a low dielectric substrate and undesired substrate effects can be eliminated, since the antenna substrate is essentially air which the

A. S. Emhemmed; K. Elgaid; L. B. Lok

2009-01-01

288

The effectiveness of an active antenna system  

Microsoft Academic Search

The noise properties of an antenna array consisting of symmetric vibrators with high-resistive wide-band antenna amplifiers and a circuit for shaping antenna's direction pattern are studied. It is shown that the high density of the vibrators improves their matching with the wide-band antenna amplifiers, which makes it possible to improve the sensitivity of a system. Bibtex entry for this abstract

G. G. Bubnov; L. N. Sneg; A. V. Aziukin; D. S. Ochkov

1980-01-01

289

Antenna Technology Shuttle Experiment (ATSE)  

NASA Astrophysics Data System (ADS)

Numerous space applications of the future will require mesh deployable antennas of 15 m in diameter or greater for frequencies up to 20 GHz. These applications include mobile communications satellites, orbiting very long baseline interferometry (VLBI) astrophysics missions, and Earth remote sensing missions. A Lockheed wrap rip antennas was used as the test article. The experiments covered a broad range of structural, control, and RF discipline objectives, which is fulfilled in total, would greatly reduce the risk of employing these antenna systems in future space applications. It was concluded that a flight experiment of a relatively large mesh deployable reflector is achievable with no major technological or cost drivers. The test articles and the instrumentation are all within the state of the art and in most cases rely on proven flight hardware. Every effort was made to design the experiments for low cost.

Freeland, R. E.; Mettler, E.; Miller, L. J.; Rahmet-Samii, Y.; Weber, W. J., III

1987-06-01

290

Compact Low Frequency Radio Antenna  

DOEpatents

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.

Punnoose, Ratish J. (Hayward, CA)

2008-11-11

291

IN!STEP INFLATABLE ANTENNA DESCRIPTION  

Microsoft Academic Search

Large size space deployable antenna structures are needed for a variety of applications. Current resources limitations within the antenna user community have resulted in the need for low cost, light weight and mechanically reliable space structures. An inflatable deployable antenna concept, under development at L'Garde has such great potential for satieing these requirements; it was selected for a NASA sponsored

Gordon Veal

292

UMTS WCDMA Network Planning with Smart Antennas  

Microsoft Academic Search

The issue of UMTS WCDMA radio network planning with smart antennas is presented in this paper. First the complexity of 3G network planning is discussed in the context of 2G and smart antennas. Then the impact that smart antennas can have on key WCDMA network parameters, such as capacity and coverage probability is demonstrated with the help of a radio

D. Tsilimantos; G. Tsoulos; D. I. Kaklamani

2007-01-01

293

Isolation Enhancement Between Two Closely Packed Antennas  

Microsoft Academic Search

This paper introduces a coupling element to enhance the isolation between two closely packed antennas operating at the same frequency band. The proposed structure consists of two antenna elements and a coupling element which is located in between the two antenna elements. The idea is to use field cancellation to enhance isolation by putting a coupling element which artificially creates

Angus C. K. Mak; Corbett R. Rowell; Ross D. Murch

2008-01-01

294

A Novel Signal Generator for Smart Antenna  

Microsoft Academic Search

This paper describes the software and hardware platform of signal generator for smart antenna system. The purpose of developing this generator is to verify the performances of DOA and DBF in smart antenna system. It is used to simulate the signals received by the antenna array. Finally, the generator was implemented based on mixed signal processing techniques. And the whole

Weizhao Li; Qingchun Zhang; Yuan Ding; Zhenghe Feng

2007-01-01

295

Optimized Antennas for Mobile Communication Base Stations  

Microsoft Academic Search

This is a synopsis of work conducted to improve the electrical and mechanical performance of antennas used for mobile communication base stations. To accomplish this we first consider the propagation characteristics to determine the optimal antenna pattern. In addition, the antennas mechanical size and profile are minimized to improve its appearance and mounting ease. The end result of this work

J. R. Sanford; J.-F. Zurcher; S. Robert

1991-01-01

296

Photonic crystal horn and array antennas  

Microsoft Academic Search

We introduce a defect-based horn antenna in a two-dimensional photonic crystal. Our numerical simulations demonstrate the efficient, highly directional nature of the antenna. It has a large operating bandwidth, low loss, and an operating frequency that is scalable to various regions of the electromagnetic spectrum. We also show that the photonic crystal horn antenna can be successfully used in an

Andrew R. Weily; Karu P. Esselle; Barry C. Sanders

2003-01-01

297

Millimetre wave high efficiency photonic crystal antennas  

Microsoft Academic Search

For a considerable time, the efficiency of planar antennas at high frequency has failed to reach its full potential. Since the planar antenna is an important element in an MMIC transceiver system, this poses a major problem. Due to the nature of the electromagnetic environment the antenna operates in, a large amount of the propagating radiation is coupled into the

Gerard Burns; I. Thayne

2003-01-01

298

Millimetre wave high efficiency photonic crystal antennas  

Microsoft Academic Search

For a considerable time, the efficiency of planar antennas at high frequency has failed to reach its full potential. Since the planar antenna is an important element in an MMIC transceiver system, this poses a major problem. Due to the nature of the electromagnetic environment the antenna operates in, a large amount of the propagating radiation is coupled into the

Gerard Burns; Harold Chong; David Edgar; Alex Ross; Khaled Elgaid; Helen McLelland; Susan Ferguson; F. McEwan; I. Thayne

2002-01-01

299

Fundamental transmitting properties of carbon nanotube antennas  

Microsoft Academic Search

Fundamental properties of dipole transmitting antennas formed by carbon nanotubes are investigated. Since carbon nanotubes can be grown to centimeter lengths, and since they can be metallic, the properties of carbon nanotubes as antenna elements are of fundamental interest. In this paper, dipole carbon nanotube antennas are investigated via a classical Hallen's-type integral equation, based on a quantum mechanical conductivity.

G. W. Hanson

2005-01-01

300

Non - foster circuitry design for antennas  

Microsoft Academic Search

A novel technique is introduced to optimize the use of negative networks in antennas. It is shown that by adding ports inside the antenna structure and appropriately applying very few negative elements, the usual at low frequencies small input resistance is increased close to characteristic impedance values while input reactance is reduced to values around zero. In that way antenna

Stavros Koulouridis

2011-01-01

301

Non-Foster design for antennas  

Microsoft Academic Search

We propose a simple but robust technique for Non- Foster circuitry design for antennas. Proposed technique can match antennas of different type and, thus, it is able to move beyond the usual Non-Foster dipole matching applications. It consists of introducing an additional port inside the antenna and loading of the port with a negative network. As shown, the novelty of

Stavros Koulouridis

2011-01-01

302

Ultra-broadband Photonic Patch Antenna  

Microsoft Academic Search

Thispaperpresents a demonstration anultra- broadband photonic antenna. Theantennautilizes external optical intensity modulators andoptic fiber tophotonically remotestheAperture Stacked Patchantennas andreplaces microwave diplexers withsimple photonic combination. The resulting photonic antennaisdemonstrated toprovide a bandwidth of110%withgainof7dBi. IndexTerms-Microstrip antennas, Microwave Photonics, Optical Fiber Antenna Remoting.

E. R. Lopez; L. A. Bui; K. Ghorbani; W. S. T. Rowe; A. Mitchell

2008-01-01

303

Photonic Antennas for Wireless Communication System  

Microsoft Academic Search

In recently years, we have introduced a new concept of photonic antennas for wireless communication system using radio-over-fiber technology. The photonic antenna is a functional device in which a photonic device such as photodetector and a planar antenna are directly integrated to form a photonic feeding RF (Radio Frequency) transmitter. This paper presented our recent research activities on the experiments

Keren Li; Masayuki Izutsu

2004-01-01

304

VLF Antarctic antenna: Impedance and efficiency  

Microsoft Academic Search

A 21-km horizontal very-low frequency (VLF) antenna has been constructed at Siple Station, Antarctica. This antenna is to be used to inject VLF waves into the magnetosphere in order to perform wave particle interaction experiments. In the present paper, the properties of this antenna are analyzed and its impedance and efficiency calculated. The electrical properties of the ice layer beneath

R. Raghuram; R. Smith; T. Bell

1974-01-01

305

Dual Band Button Antennas for Wearable Applications  

Microsoft Academic Search

A novel structure for wearable WLAN applications is presented. This antenna is a top loaded monopole and is shaped as a button. The antenna is easily disguised and is less sensitive to the clothing fabric than printed patches. The antenna is dual band at 2400MHz and 5200MHz with the omni-directional radiation patterns required for transmission with other wearable devices located

B. Sanz-Izquierdo; F. Huang; J. C. Batchelor

2006-01-01

306

Theory of antennas for ion Bernstein waves  

NASA Astrophysics Data System (ADS)

A theory of antennas for ion Bernstein wave heating has been proposed as a viable alternative to fast wave heating in the ICF domain. The radiation resistance of the Alcator C antenna is found to be more than 3 times larger than that of an equivalent dipole antenna. (AIP)

Brambilla, Marco

1987-09-01

307

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures...that are more than 60.96 m (200 ft) in height, or are located near or at a...

2011-10-01

308

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures...that are more than 60.96 m (200 ft) in height, or are located near or at a...

2012-10-01

309

Space antennas: design, analysis and measurement challenges  

Microsoft Academic Search

Modern technological demands necessitates utilization of sophisticated antenna configurations as an integral part of future satellite communications and scientific payloads. A typical configuration consists of multi offset reflector antennas illuminated by feed arrays operating at various frequency bands. Additionally, it is desired to use large reflector antennas providing improved link performances and high resolutions for various applications. An overview of

Y Rahmat-Samii

1996-01-01

310

Surface accuracy measurement system deployable reflector antennas  

Microsoft Academic Search

Conceptual optical sensor configurations for measuring the surface deformations of large, deployable space antennas are described. These antennas include precision deployable reflectors up to 30 meters diameter and 1000 GHz frequency and mesh deployable reflectors up to 100 meters diameter and 30 GHz frequency. For each representative antenna configuration, the surface deformation sensor provides continuous, real-time measurements at a sufficient

R. S. Neiswander

1979-01-01

311

An integrated rectangular dielectric resonator antenna  

Microsoft Academic Search

The use of a rectangular dielectric resonator as an antenna element is reported. The resonator is excited in its lowest order magnetic dipole mode using a microstrip line-slot combination. Measured results on the proposed antenna configuration show that the antenna has a bandwidth of about 10% and that its far field pattern is similar to that of a magnetic dipole.

A. Ittipiboon; R. K. Mongia; Y. M. M. Antar; P. Bhartia; M. Cuhaci

1993-01-01

312

A capacitively coupled polymeric internal antenna  

Microsoft Academic Search

A capacitively-coupled polymeric internal antenna is introduced for Bluetooth or GPS applications. Such an antenna can be easily fabricated on a flexible film substrate and attached to the inside surface of the plastic housing of a portable wireless device, such as a PDA. The proposed antenna saves critical space on the printed circuit board (PCB) and eliminates the need for

Khan M. Z. Shams; M. Ali

2004-01-01

313

Antenna Mask Design for SAR Performance Optimization  

Microsoft Academic Search

In this letter, an effective technique for synthetic aperture radar (SAR) antenna mask design is presented for optimizing the system performance of an active phased array SAR. The SAR antenna radiation pattern has an important effect on the system performance. Therefore, the authors derived the quantitative equations for the SAR antenna mainlobe and sidelobe mask design on the basis of

Se Young Kim; Noh Hoon Myung; Min Jeong Kang

2009-01-01

314

The diamond dipole: a Gaussian impulse antenna  

Microsoft Academic Search

When a typical narrowband antenna is excited by an ultra-wideband (UWB) impulse, the antenna rings at its resonant frequency, stretching out the waveform in time. A resonant antenna, like the bow tie, discone, or bicone have been available for years. A bow tie has a relatively high input impedance, and requires a matching balun to make it useable with a

H. G. Schantz; L. Fullerton

2001-01-01

315

Quasi-optical patch resonator antenna array  

Microsoft Academic Search

An active integrated antenna array consisting of a parallel feedback FET oscillator and a patch antenna is demonstrated. In this paper a two element array was fabricated and examined. The patch antenna was incorporated into oscillator feedback loop to enhance stability of the resonator operation frequency. Two slot apertures were embedded in the ground plane of the patch resonator and

H. Shiomi; K. Hayata; Y. Kido; S. Kawasaki

1997-01-01

316

Optical antennas direct single-molecule emission  

Microsoft Academic Search

Antennas have been used for more than a century to control the emission and collection of radio and microwave radiation. An optical analogue is of great interest as it will allow unique control of absorption and emission at the nanometre scale. Despite the intense recent research on optical antennas, one of the main functions of traditional antennas, the directing of

T. H. Taminiau; F. D. Stefani; F. B. Segerink; N. F. van Hulst

2008-01-01

317

Antenna Construction and Propagation of Radio Waves.  

ERIC Educational Resources Information Center

|Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on antenna construction and propagation of radio waves is designed to provide communicators with instructions in the selection and/or construction of the proper antenna(s) for use with current field radio equipment. Introductory materials include…

Marine Corps Inst., Washington, DC.

318

Numerical vibration analysis of a SAR antenna  

Microsoft Academic Search

Advanced military aircrafts and modern Medium\\/High Altitude Long Endurance aircraft or unmanned aerial vehicles will be equipped with structurally integrated array antennas for radar applications. The inertial forces and the aerodynamic loads will cause deformations and vibrations of the total antenna. The influence of deformations and vibrations will be most significant on array antennas, which are large in terms of

Mehmet Çelik; Radar EW

2010-01-01

319

On DOA estimation of vibrating antenna arrays  

Microsoft Academic Search

Array antennas which are integrated onto lightweight structures of aircraft and Unmanned Aerial Vehicles (UAVs) are subject to unsteady aerodynamic loads. Mechanical forces and these aerodynamic loads will cause deformation of the antenna supporting structure. As a consequence, the positions and orientations of the elements of the array antenna change. The relative phases of the respective signals of the array

Harmen Schippers; Guus Vos

2010-01-01

320

A brief history of photonic antenna reconfiguration  

Microsoft Academic Search

The primary focus of photonics for antenna systems has, historically, been on the development of link and beam steering techniques. By using photonically controlled devices and materials it is possible to produce revolutionary changes in antenna elements and in the design and properties of arrays, opening the door for a new class of antennas. In this paper we survey the

M. L. Van Blaricum

2000-01-01

321

New printed antenna with circular polarization  

Microsoft Academic Search

A new type of printed antenna element, as well as of array of elements with circular polarization is shown in this paper. Antenna has a much wider bandwidth than known circularly polarized printed antennas, mostly microstrip patches. Besides, a new concept, the method of design and realization with experimental results is also shown. Theoretical, as well as experimental results, obtained

A. Nesic; I. Radnovic; M. Mikavica; S. Dragas; M. Marjanovic

1996-01-01

322

A reconfigurable mesh reflector antenna  

NASA Astrophysics Data System (ADS)

The paper describes a novel method for controlling the coverage pattern of a spacecraft antenna. An offset mesh reflector is proposed with reconfiguration achieved by means of adjustment to forces applied at control points on the reflector surface. Synthesis software has been developed and this is demonstrated for typical regional coverage patterns. A model of the mesh based on a network of springs is used and this has been successfully verified following precision mechanical measurements using an 85 cm diameter reflector. Gold-plated molybdenum mesh has been chosen so that the antenna can be tested electrically at a frequency of 10 GHz.

Clarricoats, P. J. B.; Hai, Z.; Brown, R. C.; Poulton, G. T.; Crone, G. E.

323

Gradiometer antennas for tunnel detection  

NASA Astrophysics Data System (ADS)

The use of gradiometer antennas for detection of long conductors and detection of empty tunnels is analyzed. For reception in vertical boreholes, the gradiometer consists of two vertical electric or magnetic dipoles with a vertical separation. Both sum and difference responses are useful, but the difference responses has the potential advantage of suppressing the primary field and making the scattered field easier to detect. The difference response is most effective in suppressing the primary field for a parallel scan where the transmitting antenna and receiving gradiometer are always at the same height. Gradiometers are most advantageous at low frequencies where the scattered field is small compared to the primary field.

Hill, David A.

1992-06-01

324

Open and hybrid microstrip antennas  

NASA Astrophysics Data System (ADS)

Attention is given to the features and performance of the open microstrip antenna (OMA), which has four magnetic walls at the periphery, and the hybrid microstrip antenna (HMA), whose magnetic and electric walls share the same structure. Cavity models are used to treat both designs. While the equivalence theorem can be used, the surface must be carefully chosen in order to yield good approximations of the local electric field. Experimental and theoretical results are found to be in good agreement, especially in the case of the HMA with one electric wall. This HMA is shorter than the OMA, although both have the same frequency for a given mode.

Penard, E.; Daniel, J. P.

1984-02-01

325

Equivalent circuit for aperture antennas  

NASA Astrophysics Data System (ADS)

The commonly used equivalent circuit based on a constant-voltage generator does not correctly characterize scattering by an aperture antenna, nor does its dual, the constant-current generator. This long-standing dilemma has been resolved by combining voltage and current sources to form a constant-power source. The power generated by this source is equated to the available power in a plane wave incident on the aperture. The voltage and current of the two sources and their respective internal impedances are then completely determined from the aperture area, the impedance, the aperture efficiency, and the relative power pattern of the antenna.

Love, A. W.

1987-06-01

326

VHF/UHF Antenna-to-Antenna Coupling Test Report.  

National Technical Information Service (NTIS)

This report presents the results of coupling measurements made between pairs of commonly used communications antennas (i.e., AT-197, AS-1018, AS-1097, and AS-1181). The coupling was measured as a function of the horizontal and vertical separation distance...

K. R. Siarkiewicz R. L. White

1976-01-01

327

Visual analysis in a deployable antenna experiment [satellite antenna  

Microsoft Academic Search

To establish a large deployable antenna, monitoring and collimation are essential for reliable and precise deployment. We have developed an analysis method to detect shifts in several images, in which the combination of cross-correlations between images and approximations at subpixel precision enables us to detect shifts in images with a precision of up to 0.01 pixels. The LDREX mission; which

SHINICHI KIMURA; MAKOTO TAKEUCHI; KOICHI HARIMA; YUTARO FUKASE; HITOSHI SATO; TETSUJI YOSHIDA; AKIHIRO MIYASAKA; HIROYUKI NODA; KEI SUNAKAWA; MASANORI HOMMA

2004-01-01

328

Design and performance of a reconfigurable mesh reflector antenna. I - Antenna design. II - Antenna performance  

NASA Astrophysics Data System (ADS)

The theoretical design of reconfigurable mesh reflectors is presented together with the feasibility of achieving antenna pattern changes consistent with satellite communication applications. Factors affecting performance are identified, including the numbers and spacing of control points, the boundary conditions at the reflector edge, and the nature of the controlling force. It is concluded that a mesh reflector with an acceptable number of actuators can be used to change antenna patterns in response to typical spacecraft reconfiguration requirements. It is shown that losses due to pillowing are generally quite small and may be controlled by adjusting the dimensions of the disk or button through which the tension is applied. It is shown that tolerances in the settings of the control points are easily met, again enhancing the engineering design. Experiments performed with a motor-driven reconfigurable antenna operating at 10 GHz are described. Measured radiation patterns are compared favorably with predictions made using the methods presented in the first part.

Clarricoats, P. J. B.; Zhou, H.

1991-12-01

329

Conformal Standard Model  

NASA Astrophysics Data System (ADS)

In recent papers we have constructed the conformal theory of metric-torsional gravitation, and in this paper we shall include the gauge fields to study the conformal U(1)× SU(2) Standard Model; we will show that the metric-torsional degrees of freedom give rise to a potential of conformal-gauge dynamical symmetry breaking: consequences are discussed.

Fabbri, Luca

2012-12-01

330

Compact wideband integrated active slot antenna amplifier  

NASA Astrophysics Data System (ADS)

The design and performance of a linear tapered slot antenna integrated directly with a FET amplifier are presented. The measured radiation patterns of the antenna are linear with crosspolarization levels of 13 dB down in both the E and H plane. The measured gain of the antenna is more than 14 dB over a bandwidth of 1.75 GHz. Compared with a passive antenna, the active antenna has an extra gain of 7 dB at 9.2 GHz.

Wu, X.-D.; Chang, K.

1993-03-01

331

Atmospheric icing and broadcast antenna reflections  

NASA Astrophysics Data System (ADS)

This study assesses the effects of atmospheric icing on broadcast transmission reflections on two mountains-Mount Mansfield in northern Vermont and Mount Washington in New Hampshire. Experience and theory suggest that antenna ice accretions produce large signal reflections. Correlations between reflection coefficients and ice accretions on Rosemount ice detectors adjacent to antennas were low and occasionally negative. The unexpected correlations may be due to factors not measured, such as antenna tuning, ice type and ice location on the antenna system. Other confounding factors may include ice detector performance and methods used to compute antenna ice accretions from the ice detectors.

Ryerson, Charles C.

1988-08-01

332

Dualband Split Dielectric Resonator Antenna  

Microsoft Academic Search

A dualband dielectric resonator antenna (DRA) is designed by splitting a rectilinear dielectric resonator (DR) and carving notches off the DR. It is observed that notches engraved at different positions affect different modes. Removal of dielectric material from where the electric field is strong incurs a significant increase in resonant frequency. The abrupt change of normal electric field across the

Tze-Hsuan Chang; Jean-Fu Kiang

2007-01-01

333

Analysis of Rectangular Microstrip Antennas.  

National Technical Information Service (NTIS)

The problem of microstrip antennas covered by a dielectric substrate is formulated in terms of coupled integro-differential equations with the current distribution on the conducting patch as an unknown quantity. The Galerkin method is used to solve for th...

M. C. Bailey M. D. Deshpande

1984-01-01

334

An ultrawideband photonic crystal antenna  

Microsoft Academic Search

We present the development of a novel ultrawideband antenna structure that uses photonic crystals as a substrate to reflect the energy normally trapped within a substrate into free space. Photonic crystals are three-dimensional periodic structures that exhibit spatial three-dimensional filter properties. In order to achieve an ultrawideband photonic crystal, two photonic crystals with different periodicities are stacked in tandem. The

K. Agi; M. Mojahedi; K. J. Malloy; E. Schamiloglu

1997-01-01

335

Antenna Array Receiver for GNSS  

Microsoft Academic Search

In this paper, details about the implementation of an antenna array RF front-end devoted to GPS will be provided. The design is based on the commercial Zarlink chip GP2015. On account of the use of array signal processing algorithms, the pro- posed platform is equipped with a calibration subsystem which ensures a phase reference, and a data acquisition subsystem for

Carles Fern; Alejandro Ram ´ irez; Juan A. Fernandez Rubio

336

Antenna surface contour control system  

NASA Astrophysics Data System (ADS)

The invention is a system for automatically controlling the surface contour of a deployable and restowable antenna having a mesh reflector surface supported by a circular, folding hoop affixed to a central, telescoping column. The antenna, when deployed, forms a quad-aperture reflector with each quadrant of the mesh surface shaped to provide an offset parabolic radio frequency (RF) reflector. The hoop is supported and positioned by quartz support cords attached to the top of a column and by lower graphite hoop control cords that extend between the hoop and base of the column. The antenna, an RF reflective surface, is a gold plated molybdenum wire mesh supported on a graphite cord truss structure that includes the hoop control cords and a plurality of surface control cords attached at selected points on the surface and to the base of the column. The contour of the three-dimensional surface of the antenna is controlled by selectively adjusting the lengths of the surface control cords and the graphite hoop control cords by means of novel actuator assemblies that automatically sense and change the lengths of the lower hoop control cords and surface control cords.

Ahl, Elvin L.; Miller, James B.

1989-03-01

337

A reconfigurable mesh reflector antenna  

Microsoft Academic Search

The paper describes a novel method for controlling the coverage pattern of a spacecraft antenna. An offset mesh reflector is proposed with reconfiguration achieved by means of adjustment to forces applied at control points on the reflector surface. Synthesis software has been developed and this is demonstrated for typical regional coverage patterns. A model of the mesh based on a

P. J. B. Clarricoats; Z. Hai; R. C. Brown; G. T. Poulton; G. E. Crone

1989-01-01

338

A Reconfigurable Satellite Reflector Antenna  

Microsoft Academic Search

The paper describes a means to change the coverage zone of a spacecraft antenna by reconfiguration of the reflector surface. By using a realistic model for an offset mesh reflector, reconfiguration is successfully demonstrated for the case of two future INTELSAT regional beams. Suggestions are made concerning both the mesh characteristics and the means by which it might be controlled.

P J B Clarricoats; Z Hai; R C Brown; G T poulton; G A E Crone

1988-01-01

339

Antennas for Modern Small Satellites  

Microsoft Academic Search

Modern small satellites (MSS) are revolutionizing the space industry. They can drastically reduce the mission cost, and can make access to space more affordable. The relationship between a modern small satellite and a ldquoconventionalrdquo large satellite is similar to that between a modern compact laptop and a ldquoconventionalrdquo work-station computer. This paper gives an overview of antenna technologies for applications

S. Gao; K. Clark; M. Unwin; J. Zackrisson; W. A. Shiroma; J. M. Akagi; K. Maynard; P. Garner; L. Boccia; G. Amendola; G. Massa; C. Underwood; M. Brenchley; M. Pointer; M. N. Sweeting

2009-01-01

340

UHF Propagation from Buried Antennas.  

National Technical Information Service (NTIS)

The paper poses, and attempts to answer, some of the questions involved when a UHF antenna is buried in the ground. A description of the basic theory is given, together with illustrative calculations for many situations of interest. Graphs are presented f...

G. A. Hufford

1969-01-01

341

Experimental Completely Overlapped Subarray Antenna.  

National Technical Information Service (NTIS)

A completely overlapped subarray antenna was designed, fabricated, and tested to demonstrate its broad-band, low sidelobe, wide scan angle performance. It uses time delay steering at the inputs to a transform feed, which illuminates a phase-shifter steere...

H. L. Southall D. T. McGrath

1986-01-01

342

Truncated Icosahedral Gravitational Wave Antenna  

Microsoft Academic Search

A spherical gravitational wave detector can be equally sensitive to a wave from any direction, and also able to measure its direction and polarization. We derive a set of equations to describe the mechanics of a spherical antenna coupled to an arbitrary number of attached mechanical resonators. A special arrangement of 6 resonators is proposed, which we term a Truncated

Stephen Michael Merkowitz

1995-01-01

343

Wideband Optical TTD SAR Antenna  

Microsoft Academic Search

Optical beam forming networks (OBFN) are an interesting alternative for the design of wideband antenna arrays. They are potentially more power efficient and lighter than their microwave counterparts. These two characteristics make them especially appealing in space remote sensing applications. However, in a practical implementation of OBFN in a real SAR system, different architectural and technological tradeoffs need to be

F. Dalmases; S. Blanch; J. Romeu; L. Jofre; B. Vidal; J. Marti; I. McKenzie; E. Vez; J. Santamaria

2006-01-01

344

Quasi-optical antenna duplexer  

Microsoft Academic Search

For the antenna duplexer composed of metallic gratings, results of theoretical and experimental studies are presented. A 94 GHz device tested at a low power level has provided the transmit-receive isolation -45 dB; the transmission loss did not exceed -0.1 dB within ~4% frequency bandwidth

J. L. Hirshfield; P. D. Kolchin; N. V. Kuzikov; V. I. Petelin

2000-01-01

345

Mathematics of Antennas: Annotated Bibliography.  

National Technical Information Service (NTIS)

This annotated bibliography deals with theoretical aspects of antennas. The 199 entries are arranged in alphabetical order by year with the following breakdown: 1961--52 entries, 1962--38 entries, 1963--49 entries, and 1964--60 entries. Other information ...

L. Kacinskas

1966-01-01

346

Mutual coupling between microstrip antennas  

NASA Astrophysics Data System (ADS)

A theoretical study of mutual coupling between microstrip antennas is presented. The cavity method is used, and from the equivalence theorem application the problem is reduced to interaction of two magnetic loops. The mutual impedance is then calculated from the reaction theorem. Theoretical results and measurements are in good agreement

Penard, E.; Daniel, J.-P.

1982-07-01

347

Directive photonic-bandgap antennas  

Microsoft Academic Search

This paper introduces two new photonic bandgap (PBG) material applications for antennas, in which a photonic parabolic reflector is studied. It is composed of dielectric parabolic layers associated to obtain a PBG material. The frequency gap is used to reflect and focus the electromagnetic waves. This device has been designed using a finite-difference time-domain (FDTD) code. FDTD computations have provided

M. Thevenot; C. Cheype; A. Reineix; B. Jecko

1999-01-01

348

Antenna and Human Body Interaction  

Microsoft Academic Search

The antenna radiation pattern and other charac- teristics are significantly altered by the presence of the human body. This interaction as well as the resultant deposition of microwave power in the body (specific absorption rate—SAR) are of particular interest for cellular telephones and similar communication devices. This paper builds on and extends the previous analyses of parameters that influence the

Michal Okoniewski; Maria A. Stuchly

349

Spatial impulse response of lithographic infrared antennas.  

PubMed

We present measurements of the spatial response of infrared dipole and bow-tie lithographic antennas. Focused 10.6-microm radiation was scanned in two dimensions across the receiving area of each antenna. Deconvolution of the beam profile allowed the spatial response to be measured. The in-plane width of the antenna's spatial response extends approximately one dielectric wavelength beyond the metallic structure. Determination of an antenna's spatial response is important for several reasons. The power collected by the antenna can be calculated, if the collection area and the input irradiance (watts per square centimeter) are known. The actual power collected by the antenna is required for computation of responsivity and noise-equivalent power. In addition, the spatial response provides insight into the current-wave modes that propagate on an antenna and the nature of the fringe fields that exist in the adjacent dielectric. PMID:18305584

Fumeaux, C; Boreman, G D; Herrmann, W; Kneubühl, F K; Rothuizen, H

1999-01-01

350

Indoor throughput and range improvements using standard compliant AP antenna diversity in IEEE 802.11a and ETSI HIPERLAN\\/2  

Microsoft Academic Search

This paper explores the application of space-time diversity techniques to enhance the performance of 5 GHz WLAN. The analysis is based on systems conforming to either the IEEE 802.11a or ETSI HIPERLAN\\/2 standard. Two antennas are assumed at the access point (AP) with a single antenna at the mobile terminal (MT). Downlink (DL) improvements are offered via the application of

M. K. Abdul Aziz; M. R. G. Butler; A. Doufexi; A. I. R. Nix; P. N. Fletcher

2001-01-01

351

Design and performance of a reconfigurable mesh reflector antenna. I - Antenna design. II - Antenna performance  

Microsoft Academic Search

The theoretical design of reconfigurable mesh reflectors is presented together with the feasibility of achieving antenna pattern changes consistent with satellite communication applications. Factors affecting performance are identified, including the numbers and spacing of control points, the boundary conditions at the reflector edge, and the nature of the controlling force. It is concluded that a mesh reflector with an acceptable

P. J. B. Clarricoats; H. Zhou

1991-01-01

352

Radio pill antenna range test  

NASA Astrophysics Data System (ADS)

In order to investigate the potential of a proposed 'radio pill' beacon transmitter, a range test experiment was devised and carried out in the VHF frequency range. Calculations and previous work indicated that optimum sensitivity and, thus, distance would be obtained in this frequency range provided body radio-frequency (RF) absorption was not too great. A ferrite-core loop antenna is compatible with a pill geometry and has better radiation efficiency than an air core loop. The ferrite core may be a hollow cylinder with the electronics and batteries placed inside. However, this range test was only concerned with experimentally developing test range data on the ferrite core antenna itself. A one turn strap loop was placed around a 9.5 mm diameter by 18.3 mm long stack of ferrite cores. This was coupled to a 50 Omega transmission line by 76 mm of twisted pair line and a capacitive matching section. This assembly was excited by a signal generator at output levels of -10 to +10 dBm. Signals were received on a VHF receiver and tape recorder coupled to a 14 element, circularly polarized Yagi antenna at a height of 2.5 m. Field strength measurements taken at ranges of 440, 1100, and 1714 m. Maximum field strengths referenced to 0 dBm transmitter level were -107 to -110 dB at 440 m, -124 to -127 dBm at 1100 m, and -116 to -119 dBm at 1714 m when the antenna cylinder was horizontal. Field strengths with a vertical antenna were about 6 dB below these values. The latter transmit site was elevated and had a clear line-of-site path to the receiving site. The performance of this test antenna was better than that expected from method-of-moment field calculations. When this performance data is scaled to a narrow bandwidth receiving system, ground level receiving ranges of a few to 10 km can be expected. Clear line-of-sight ranges where either or both the transmitter and receiver are elevated could vary from several km to 100 km.

Cummins, W. F.; Kane, R. J.

1992-05-01

353

On correlations between dual-polarized base station antennas  

Microsoft Academic Search

Several diversity techniques employing multiple antennas in the base station have been developed for mobile communication systems. However, the performance of diversity methods strongly depends on the correlation between antenna elements. When multiple copolarized antennas are used in base station, the practical factor limiting the number of diversity branches is the required antenna separation, because large antenna separation makes the

Jyri Hamalainen; Risto Wichman

2003-01-01

354

Inductively Coupled Plasma Source with Internal Straight Antenna  

Microsoft Academic Search

An inductively coupled plasma source with an internal straight antenna was developed. By inserting an antenna into plasma, the induction of a strong electric field in the plasma and the efficient transmissions of power to plasma is enabled. However, there was a practical problem in that antenna sputtering occurred. Suppression of antenna sputtering and methods of insulating the antenna were

Masaaki Kanoh; Keiji Suzuki; Jyunichi Tonotani; Katsuaki Aoki; Masashi Yamage

2001-01-01

355

Telecommunications antennas for the Juno Mission to Jupiter  

Microsoft Academic Search

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

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

2012-01-01

356

Planar Patch Antenna Using Temperature Stable High-Permittivity Ceramics  

Microsoft Academic Search

Temperature stable high-permittivity dielectric ceramic materials have been applied in the fabrication of a planar patch antenna. The planar patch antenna is fed with a microstrip line. The planar patch antenna was investigated by examining the transmission line model to initially determine the dimension of the designed planar patch antenna. Fabricated planar patch antenna was measured by an Agilent N5230A

Y. C. Chen; J. Y. Lin; S. M. Tsao

2007-01-01

357

Integrated Quantum Dot Schottky Diodes for RECTENNA (Rectifying Antenna)  

Microsoft Academic Search

In this paper we will present our latest research results of integrated quantum dot Schottky diodes and integrated silicon antenna for RF applications. Both, the quantum dot Schottky diodes and the antenna are integrated on Si substrates forming a simple mm-wave detection system, the rectifying antenna (RECTENNA). Within this work a specific antenna design, 1-dimensional array (single line antenna), will

H. Xu; A. Karmous; M. Morschbach; O. Kirfel; S. Spiessberger; E. Kasper

2009-01-01

358

Wind-induced Dynamics Of A Deep Space Network Antenna  

Microsoft Academic Search

Accurate spacecraft tracking by the NASA Deep Space Network (DSN) antennas must be assured during changing weather conditions. Wind disturbances are the main source of antenna vibrations, and consequently tracking errors. A wind force model is developed, and simulation results of wind-induced vibrations and pointing errors of the DSN antennas are presented. The antenna model includes the antenna structure, the

W. Gawronski; B. Bienkiewicz; R. E. Hill

1994-01-01

359

The planar parabolic optical antenna.  

PubMed

One of the simplest and most common structures used for directing light in macroscale applications is the parabolic reflector. Parabolic reflectors are ubiquitous in many technologies, from satellite dishes to hand-held flashlights. Today, there is a growing interest in the use of ultracompact metallic structures for manipulating light on the wavelength scale. Significant progress has been made in scaling radiowave antennas to the nanoscale for operation in the visible range, but similar scaling of parabolic reflectors employing ray-optics concepts has not yet been accomplished because of the difficulty in fabricating nanoscale three-dimensional surfaces. Here, we demonstrate that plasmon physics can be employed to realize a resonant elliptical cavity functioning as an essentially planar nanometallic structure that serves as a broadband unidirectional parabolic antenna at optical frequencies. PMID:23194111

Schoen, David T; Coenen, Toon; García de Abajo, F Javier; Brongersma, Mark L; Polman, Albert

2012-12-07

360

Conformations of proline  

Microsoft Academic Search

The present study concerns the energies of the conformations of proline. We present results of an improved molecular mechanics calculation for ring conformations of Ac-Pro-OCHâ and for the s-cis and s-trans conformations. Internal coordinates including all torsions have been calculated from crystal coordinates for more than 40 x-ray determinations to give a consistent set of data which define proline ring

DeLos F. DeTar; Narender P. Luthra

1977-01-01

361

Optically smart active antenna arrays  

Microsoft Academic Search

A prototype X-band active antenna array with adaptive optical processing is presented. The optical processor, referred to as an auto-tuning filter, is able to extract the strongest principal component in a two-signal space with up to 30 dB enhancement with respect to the other signals. The processor is compact (8 cm by 4 cm) and scalable to a large number

Dana Z. Anderson; V. Damiao; Edeline Fotheringham; Darko Popovic; Stefania Romisch; Zoya Popovic

2000-01-01

362

Diversity antennas for isotropic coverage  

Microsoft Academic Search

Three-element polarization \\/ pattern diversity antennas for isotropic coverage (covering all directions and any linear polarization) are presented for frequencies around 1.5 GHz. Based on perpendicularly mounted, co-centred dipoles, a broadband (VSWR <; 1.5 over 15% bandwidth) and compact (kr = 0.9 at the lower frequency band edge) design is possible. Radiation pattern and gain are similar to those of

Dimitra Psychogiou; Jan Hesselbarth

2010-01-01

363

International Conference on Antennas and Propagation, 5th, University of York, England, Mar. 30-Apr. 2, 1987, Proceedings. Part 1 - Antennas. Part 2 - Propagation  

NASA Astrophysics Data System (ADS)

Various papers on antennas and propagation are presented. The general topics considered include: mechanical aspects of antennas, millimeter wave antennas, numerical methods, satellite communication propagation, mobile antennas, frequency-selective surfaces, VHF and UHF propagation, millimeter propagation, wideband antennas, microstrip antennas, ionospheric propagation, reflector antennas, phased arrays, urban and mobile propagation, propagation at short range and in tunnels, VHF/UHF and broadcast antennas, the past 100 years in antennas and propagation, adaptive antennas, antenna measurements, array antennas, line-of-sight propagation, horn and feed antennas, scattering and diffraction, electromagnetic theory, tropospheric propagation, and remote sensing.

364

Lower Hybrid Antenna Design for MST  

NASA Astrophysics Data System (ADS)

Inter-digital line antennas are being used to test the feasibility of lower hybrid current drive in MST. The antennas use ?/4 resonators and launch slow waves at 800 MHz with n? ~ 7.5. Routine operation has been achieved with a good impedance match between antenna and plasma. High power antenna design improvements include larger vacuum feed-throughs, better impedance matching, and rf instrumentation on all resonators. The antenna and feed-through modeling was performed with CST Microwave Studio™. The pulse-forming network that powers the klystron is being upgraded to a 50 kV - 30 ms pulse. The goal for the LHCD system on MST is a modular design that can handle 300 kW per antenna.

Goetz, J. A.; Thomas, M. A.; Kaufman, M. C.; Oliva, S. P.

2005-09-01

365

Antenna coupling circuit for magnetic resonance imaging  

SciTech Connect

A coupling circuit for coupling an inductive coil antenna of a magnetic resonance imaging system to receiver circuitry is described comprising: capacitive means, coupled in parallel with the antenna, for providing capacitive reactance in the coupling circuit; resistive means, coupled in parallel with the antenna and with the capacitive means, for providing resistance R in the coupling circuit when the inductive reactance of the coupling circuit is equal to the capacitive reactance of the coupling circuit; and capacitive transformer means, coupled between the antenna and the receiver circuitry in series with the antenna, for transforming the resistance value R of the resistive means into a transformed resistance value R', thereby increasing the apparent resistance of the coupling circuit in parallel with the antenna.

Fox, T.R.

1988-03-15

366

Photonic crystal horn and array antennas.  

PubMed

We introduce a defect-based horn antenna in a two-dimensional photonic crystal. Our numerical simulations demonstrate the efficient, highly directional nature of the antenna. It has a large operating bandwidth, low loss, and an operating frequency that is scalable to various regions of the electromagnetic spectrum. We also show that the photonic crystal horn antenna can be successfully used in an array configuration that uses a feed network made from photonic crystal waveguide circuits. The feed network and antennas have been integrated into a single photonic crystal device. This photonic crystal array antenna is shown to have high directivity and compact size while retaining the advantages of the photonic crystal horn antenna. PMID:12935272

Weily, Andrew R; Esselle, Karu P; Sanders, Barry C

2003-07-16

367

Status of the ALMA Antenna Production  

NASA Astrophysics Data System (ADS)

The design of the ALMA antennas began in 1999 with a prototyping phase. Two antenna prototypes were built, extensively tested at the VLA site in New Mexico and evaluated in 2003. It was decided to proceed to procurement with two parallel calls for tenders based on the two prototypes. In 2005 contracts were placed with the US VertexRSI and the European AEM Consortium for 25 antennas each. An update on the two designs and the production progress is presented. The Japanese antennas (both 7 and 12 m) are being built by Mitsubishi, which also built an additional antenna prototype. The first antennas have recently arrived at the integration facility at the ALMA Operations Support Facility (OSF).

Stanghellini, Stefano

2007-12-01

368

Thermal control of a satellite truss antenna  

Microsoft Academic Search

Thermal control calculations on a thermal satellite antenna are described and results are presented. The deployable truss-antenna with 3.5 m in diameter consists of a carbon fiber reinforced plastic truss-work and a mesh-reflector. It was designed as a transmitting antenna for a synchronous satellite. Three critical orbit positions with respect to thermal control, and the eclipse were considered. Simplifying assumptions

K. H. Reichmann

1975-01-01

369

Internal antennas for digital TV receiver  

Microsoft Academic Search

Various types of internal antennas suitable for digital TV receiver have been investigated. These include rectangular plate loop structure, 1\\/2?? monopole, and L-dipole. Evaluations of the internal antennas were done, numerically and experimentally, to obtain some electrical properties such as S11, VSWR, gain and radiation pattern. All the fabricated antennas are incorporated inside the TV receiver body. This allows more

E. Palantei; A. Andani; M. Baharuddin; N. K. Nauman; S. Syarif; M. Anshar; NNRA Mokobombang; A. Suyuti; Z. Muslimin; Z. Zainuddin; A. Indrabayu; F. Mayasari; S. Kanata; Z. B. Hasanuddin; N. Zain; D. Mariana

2011-01-01

370

A MIMO System With Multifunctional Reconfigurable Antennas  

Microsoft Academic Search

A multiple-input-multiple-output (MIMO) system equipped with a new class of antenna arrays, henceforth referred to as multifunction reconfigurable antenna arrays (MRAAs), is investigated. The elements of MRAA, i.e., multifunction reconfigurable antennas (MRAs) presented in this work are capable of dynamically changing the sense of polarization of the radiated field thereby providing two reconfigurable modes of operation, i.e., polarization diversity and

Bedri A. Cetiner; Enis Akay; Ersin Sengul; Ender Ayanoglu

2006-01-01

371

Microstrip base station antennas for cellular communications  

Microsoft Academic Search

Four base-station antenna products using microstrip technology have been developed for use in cellular communications. The antennas operate in the 800-900-MHz range and are designed to work in a 60° sectored arrangement. The main product is a half-cylinder three-beam radome-enclosed antenna. There are three microstrip planar array panels within the half-cylindrical radome. Each microstrip planar array panel illuminates one 60°

Peter Strickland; Fazal Bacchus

1991-01-01

372

Sun focusing by satellite antenna reflectors  

Microsoft Academic Search

Solar flux reflected into the focal plane of direct television satellite antennas was estimated using a 2 sqm antenna model. Results show that the antenna reflects 0.15 solar constant flux into its focal plane. Measurement imprecision due to environment inhomogeneity is estimated at 0.05 solar constant. The flux is diffuse and very homogenous in a 50cm diameter zone around the

I. Alet

1983-01-01

373

Broadband omnidirectional metal-plate monopole antenna  

Microsoft Academic Search

A novel broad-band omnidirectional metal-plate monopole antenna is presented. The proposed antenna is a step-shaped metal-plate monopole, which is easily fabricated from bending a metal plate (a 0.2 mm thick brass sheet used in this study). The proposed antenna shows improved omnidirectional radiation for frequencies across a very wide operating bandwidth (frequency ratio about 1:3), compared to a corresponding planar

Kin-Lu Wong; Saou-Wen Su; Chia-Lun Tang

2005-01-01

374

Organic-Inorganic Composites as Photonic Antenna  

Microsoft Academic Search

A photonic antenna system is an organized multi-component arrangement in which several chromophoric molecular species absorb the incident light and channel the excitation energy to a common acceptor component. Photonic antenna materials, based on dye-zeolite L composites, collect excitation energy and transport it over large distances. Fine tuning of dye-loaded zeolite L photonic antenna materials in the size range of

Gion Calzaferri

2001-01-01

375

Multiband bowtie antenna based on fractal geometry  

Microsoft Academic Search

The expansion of the wireless communication market is driving the increasing demand for low-profile multi-band antennas for a large variety of applications in personal and satellite communication systems. Most of the existing printed antennas designs operate at one or double frequencies, while the demand is for versatile multi-frequency antennas operational in GSM, GPS, UMTS and Bluetooth applications. The nature of

Yiftah Gelman; E. Beri-Ari; Reuven Shavit

2004-01-01

376

The phase center of a monopole antenna  

NASA Astrophysics Data System (ADS)

A phase center is calculated for the idealized model of a monopole antenna with an infinitely large, perfectly conducting ground plane. The boundary integral method is used to determine the surface current density on the conducting parts of the configuration. The value of the input admittance is calculated for a monopole antenna with a flat top and for a monopole antenna with a hemispherical cap, and results are compared with experimental results of Sandor and Holly (1969), showing excellent agreement.

de Jong, G.

1982-04-01

377

A metallic Fabry-Perot directive antenna  

Microsoft Academic Search

We report the design of a directive antenna using the electromagnetic resonances of a Fabry-Perot cavity. The Fabry-Perot cavity is made of a ground plane and a single metallic grid. The resonance is excited by a patch antenna placed in the cavity at the vicinity of the ground plane. The two remarkable features of Fabry-Perot cavity antennas are, first, that

Nicolas Guérin; Stefan Enoch; Gérard Tayeb; Pierre Sabouroux; Patrick Vincent; Hervé Legay

2006-01-01

378

AMSU-A antenna pattern corrections  

Microsoft Academic Search

A procedure for making antenna pattern corrections to antenna temperatures of the advanced microwave sounding unit-A (AMSU-A) is developed. Antenna efficiencies, fractions of total power over three different solid-angle regions subtended at the satellite by the Earth (plus atmosphere below 20 km), cold space, and the satellite platform, were calculated at 30 Earth views and four possible cold space calibration

Tsan Mo

1999-01-01

379

ULTRA WIDEBAND FRACTAL MICROSTRIP ANTENNA DESIGN  

Microsoft Academic Search

Abstract—Newfractal geometry for microstrip antennas is presented in this paper. This fractal structure is implemented on hexagonal and,several iteration is applied on initial shape.,This antenna has lowprofile, lightw eight and is easy to be fabricated and has successfully demonstrated multiband and broadband characteristics. The simulated results showthat proposed antenna has very good performance in impedance bandwidth and radiation pattern.

Abolfazl Azari; Javad Rowhani

2008-01-01

380

Resonant antenna based on CRLH TL  

Microsoft Academic Search

In this paper, a study of the compact microstrip antenna based on composite right\\/left handed (CRLH) metamaterial transmission line is presented. The physical size and operational frequencies of the antenna are determined by the CRLH metamaterial's unit cell. The antenna exhibits monopolar radiation at its fundamental mode of resonant frequency. As it is well known that the composite right\\/left-handed (CRLH)

K. L. Sheeja; Nabil Dakhli; P. K. Sahu; S. K. Behera

2010-01-01

381

Wideband Antenna for Underground Soil Scout Transmission  

Microsoft Academic Search

The underground soil scout system introduces a need for a small-size antenna capable of adequate radiation efficiency in soils of different moisture contents at the frequency 0.869 GHz. Such an underground antenna is created for the first time. The high permittivity of soil is utilized to downsize the instrument. A prototype design of an underground single-ended elliptical monopole antenna (USEMA)

M. J. Tiusanen

2006-01-01

382

The flight evaluation of aircraft antennas  

Microsoft Academic Search

Flight evaluation of communication-navigation-identification antennas installed on new types of aircraft is required to confirm model measurements. The paper reviews the parameters involved in such an evaluation under both standard and nonstandard propagation conditions. The predicted signal level across the receiver terminals connected to an isotropic antenna is employed as the standard of comparison with the scale-model antenna patterns. The

G. Leopard

1960-01-01

383

A new kind of millimeter wave antenna  

NASA Astrophysics Data System (ADS)

A new type of millimeter-wave leaky wave antenna with extended frequency band and improved polarization characteristics is described. A general analysis method is presented which can also be used to analyze other metal loaded-dielectric waveguide antennas. The antenna features a slab dielectric waveguide loaded with thin metal film meander lines. These wires constitute discontinuities of the dielectric waveguide, so that the induced current in the wires excites different modal fields, including surface wave modes and radiation modes.

Xu, J. D.; Chen, G. R.

384

A Universal UHF RFID Reader Antenna  

Microsoft Academic Search

A broadband circularly polarized patch antenna is proposed for universal ultra-high-frequency (UHF) RF identification (RFID) applications. The antenna is composed of two corner-truncated patches and a suspended microstrip line with open-circuited termination. The main patch is fed by four probes which are sequentially connected to the suspended microstrip feed line. The measurement shows that the antenna achieves a return loss

Zhi Ning Chen; Xianming Qing; Hang Leong Chung

2009-01-01

385

Effective Wavelength Scaling for Optical Antennas  

Microsoft Academic Search

In antenna theory, antenna parameters are directly related to the wavelength lambda of incident radiation, but this scaling fails at optical frequencies where metals behave as strongly coupled plasmas. In this Letter we show that antenna designs can be transferred to the optical frequency regime by replacing lambda by a linearly scaled effective wavelength lambdaeff=n1+n2lambda\\/lambdap, with lambdap being the plasma

Lukas Novotny

2007-01-01

386

Quasi-optical slot antenna SIS mixers  

Microsoft Academic Search

A quasi-optical SIS mixer designed for efficient radiation coupling is described. The mixer uses a twin-slot antenna which has the advantages of a good beam pattern and a low impedance. The radiation and impedance characteristics of the antenna were obtained from a moment-matched calculation. Tapered superconducting microstrip transmission lines are used to carry the radiation from the slot antennas to

Jonas Zmuidzinas; H. G. LeDuc

1992-01-01

387

Personnel protection from electrocution through whip antennas  

Microsoft Academic Search

Summary form only given, as follows. A device for personnel protection from electrocution through whip antennas occurring when the antenna comes in touch with wires of high voltage lines is described. It is a high-pass filter implemented as a non-linear blocking capacitor possessing a falling capacitance-voltage characteristic installed in the middle part of the antenna. This filter presents low impedance

A. Pokryvailo; S. Wald; E. Sayag; A. Adler

2001-01-01

388

The compact antenna range for experimental improvement of space vehicles antennas  

Microsoft Academic Search

We present estimates for some characteristics of a new compact antenna range for the experimental improvement and performance of tests of antennas of microwave range. The method of wave optics in view of the theory of Fresnel's diffraction was used to determine one of the main parameters of compact antenna measurement range, namely, the distance between a collimation mirror and

V. V. Ovsyanikov; V. M. Popel; A. L. Ol'Shevskiy; P. V. Popel

2004-01-01

389

Radiation pattern measurements of electrically large antennas using a compact antenna test range at 180 GHz  

Microsoft Academic Search

A 3 m-width millimeter-wave compact antenna test range for antenna measurements up to 200 GHz has been constructed at Queen Mary College. Measurements of a 400 mm aperture width 90 deg offset test antenna operating at 180 GHz are presented, indicating that a 62 dB dynamic range is achievable.

C. G. Parini; C. J. Prior

1988-01-01

390

Cable-catenary large antenna concept  

NASA Astrophysics Data System (ADS)

Deployable to very large diameters (over 1000 ft), while still remaining compatible with a complete satellite system launch by STS, the cable-catenary antenna comprises: 8 radial deployable boom masts; a deployable hub and feed support center mast; balanced front and back, radial and circumferential catenary cabling for highly accurate (mm) surface control; no interfering cabling in the antenna field; and an RF reflecting mesh supported on the front catenaries. Illustrations show the antenna-satellite system deployed and stowed configurations; the antenna deployment sequence; the design analysis logic; the sizing analysis output, and typical parametric design data.

Akle, W.

1985-04-01

391

Small antennas for communication over sea ice  

NASA Astrophysics Data System (ADS)

The invention described herein relates to an antenna system which makes use of the waveguide properties of sea ice. The antenna system broadly includes at least one antenna wire extending along and preferably in contact with a sea ice surface for transmitting and receiving substantially vertically polarized radio waves. In a first embodiment, the antenna system has a single antenna wire connected to a tuner at one end and grounded to seawater at a second end. The antenna system also has a second length of wire attached to the tuner. The second wire passes through a hole in the sea ice and is also grounded to the seawater beneath the sea ice. In an alternative embodiment, only the second wire is grounded to the seawater beneath the sea ice. The single antenna wire in this embodiment is ungrounded. In yet another embodiment, the antenna system comprises a dipole antenna wire laying on the surface of the sea ice and being connected to a radio for transmitting and receiving radio signals.

Mileski, Paul

1993-10-01

392

Broadband slant linearly polarized biconical antenna  

NASA Astrophysics Data System (ADS)

A broadband biconical antenna with a slant linear polarizer, operating over 2-26 GHz range was designed and fabricated. The results of tests are presented, including the return loss plot of the antenna, radiation patterns at 2, 10, and 26 GHz for vertical and horizontal polarizations in azimuth and elevation planes, and curves indicating the elevation beam-width and gain of the antenna vs. frequency. The antenna gives an omni deviation of +/- 3 dB over 2-26 GHz. It is highly compact, and thus is suitable for systems where space requirements are very stringent.

Lakshminarayana, D.; Prasad, R. V. H.; Murthy, T. G. K.

1993-06-01

393

Backfire antennas constructed with coaxial circular loops  

NASA Astrophysics Data System (ADS)

The radiation characteristics of backfire antennas constructed entirely of circular loops are studied. A comparison between this type of backfire antenna and the conventional one, made of a solid reflector, reveals that the optimum dimensions of the reflector and the peripheral rim are approximately the same for both kinds of antennas. In addition, it is found that as few as six loops are sufficient to construct the optimum reflector, and almost the same number of loops are required to form the optimum peripheral rim. The new structure reduces the weight, windage, and obstruction of view which accompany solid reflectors. In addition, the new antenna lends itself to exact analytical investigation.

Shoamanesh, A.; Shafai, L.

1980-09-01

394

Radiation pattern of a borehole radar antenna  

USGS Publications Warehouse

To understand better how a borehole antenna radiates radar waves into a formation, this phenomenon is simulated numerically using the finite-difference, time-domain method. The simulations are of two different antenna models that include features like a driving point fed by a coaxial cable, resistive loading of the antenna, and a water-filled borehole. For each model, traces are calculated in the far-field region, and then, from these traces, radiation patterns are calculated. The radiation patterns show that the amplitude of the radar wave is strongly affected by its frequency, its propagation direction, and the resistive loading of the antenna.

Ellefsen, K. J.; Wright, D. L.

2002-01-01

395

Chlorosomes: Antenna Organelles in Photosynthetic Green Bacteria  

Microsoft Academic Search

Chlorosomes are the light-harvesting antenna organelles found in two groups of bacteria, the green\\u000a sulfur bacteria and the green filamentous bacteria, collectively known as photosynthetic green bacteria.\\u000a Chlorosomes consist mostly of aggregated bacteriochlorophyll (BChl) c,\\u000a d, or e and are the largest antenna\\u000a structures known. Unlike other light-harvesting antenna structures, the major antenna pigments (BChl c, d, or e)\\u000a form

Niels-Ulrik Frigaard; Donald Bryant

396

Computed performance of the half-scale accurate antenna reflector  

NASA Astrophysics Data System (ADS)

The performance of the half-scale, accurate antenna reflector was studied. The antenna is evaluated for use as a compact range reflector. The reflector is studied for use with three separate feed antennas.

Lambert, Kevin M.

1989-05-01

397

Antennas for the Vlf Region and Lf Region.  

National Technical Information Service (NTIS)

A description is given of all the transmitting and receiving antennas that have been used for VLF project studies. The antenna efficiency is discussed and helical transmitting antennas are described in a special chapter. Various diagrams plotted in accord...

R. Klein

1970-01-01

398

47 CFR 101.125 - Temporary fixed antenna height restrictions.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Temporary fixed antenna height restrictions. 101.125 Section 101...Standards § 101.125 Temporary fixed antenna height restrictions. The overall antenna structure heights employed by mobile stations in the...

2011-10-01

399

47 CFR 73.614 - Power and antenna height requirements.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Power and antenna height requirements. 73.614 Section 73...Stations § 73.614 Power and antenna height requirements. (a) Minimum requirements...horizontal direction. No minimum antenna height above average terrain is specified....

2011-10-01

400

47 CFR 22.1011 - Antenna height limitations.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna height limitations. 22.1011 Section 22.1011...Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61...

2011-10-01

401

47 CFR 22.1011 - Antenna height limitations.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna height limitations. 22.1011 Section 22.1011...Radiotelephone Service § 22.1011 Antenna height limitations. The antenna height of offshore stations must not exceed 61...

2012-10-01

402

47 CFR 101.125 - Temporary fixed antenna height restrictions.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Temporary fixed antenna height restrictions. 101.125 Section 101...Standards § 101.125 Temporary fixed antenna height restrictions. The overall antenna structure heights employed by mobile stations in the...

2012-10-01

403

47 CFR 73.614 - Power and antenna height requirements.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Power and antenna height requirements. 73.614 Section 73...Stations § 73.614 Power and antenna height requirements. (a) Minimum requirements...horizontal direction. No minimum antenna height above average terrain is specified....

2012-10-01

404

High Selectivity Electromagnetic Bandgap Device and Antenna System.  

National Technical Information Service (NTIS)

An antenna system includes an antenna element and an electromagnetic bandgap element proximate the antenna element wherein the electromagnetic bandgap element is optimized for narrow bandwidth operation thereby providing radiofrequency selectivity to the ...

D. H. Werner M. J. Wilhelm P. L. Werner

2004-01-01

405

Electrical Performance of Wire Mesh for Spacecraft Deployable Reflector Antennas.  

National Technical Information Service (NTIS)

Mobile satellite communications systems require large, high gain antennas at the spacecraft to minimize the antenna gain and power requirements for mobile user elements. The use of a deployable reflector antenna for these applications provides a lightweig...

G. Turner

1993-01-01

406

Passive Intermodulation Generation in Wire Mesh Deployable Reflector Antennas.  

National Technical Information Service (NTIS)

Deployable reflector antennas represent a proven technology with obvious benefits for mobile satellite applications. Harris Corporation has provided deployable reflector antennas for NASA's Tracking and Data Relay Satellite System (TDRSS). These antennas ...

G. M. Turner

1993-01-01

407

RCS of circular carbon NANO tube antenna array  

Microsoft Academic Search

A novel THz antenna structure, made of carbon nanotube arrays is suggested. Using CST MICROWAVE STUDIO (CST MWS), the capabilities of carbon nanotube terahertz (THz) antenna arrays have been simulated and this CNT antenna array has been fabricated.

H. Zareie; N. Davoudzadeh; M. Tafazoli; G. Fard; M. Hasan; Shamsoddin

2009-01-01

408

47 CFR 17.8 - Establishment of antenna farm areas.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Establishment of antenna farm areas. 17.8 Section 17.8...CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA STRUCTURES Federal Aviation Administration...Criteria § 17.8 Establishment of antenna farm areas. (a)...

2010-10-01

409

47 CFR 17.4 - Antenna structure registration.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Antenna structure registration. 17.4 Section...CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA STRUCTURES General Information § 17.4 Antenna structure registration. (a)...

2009-10-01

410

47 CFR 17.8 - Establishment of antenna farm areas.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Establishment of antenna farm areas. 17.8 Section 17.8...CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA STRUCTURES Federal Aviation Administration...Criteria § 17.8 Establishment of antenna farm areas. (a)...

2009-10-01

411

47 CFR 17.4 - Antenna structure registration.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna structure registration. 17.4 Section...CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA STRUCTURES General Information § 17.4 Antenna structure registration. (a)...

2010-10-01

412

A Circular Disk Microstrip WLAN Antenna for Wearable Applications  

Microsoft Academic Search

The evolution of antenna technology for man-machine interface has taken quantum leaps in utilizing textile materials as antenna substrates. In future this will allow complete freedom to develop body-worn antenna systems embedded in so- called \\

S. Sankaralingam; B. Gupta

2009-01-01

413

Passive wireless antenna sensors for crack detection and shear/compression sensing  

NASA Astrophysics Data System (ADS)

Despite the fact that engineering components and structures are carefully designed against fatigue failures, 50 to 90% of mechanical failures are due to fatigue crack development. The severity of the failure depends on both the crack length and its orientation. Many types of sensors are available that can detect fatigue crack propagation. However, crack orientation detection has been rarely reported in the literature. We evaluated a patch antenna sensor capable of detecting crack propagation as well as crack orientation changes. The aim of these sensors would be to evaluate the real-time health condition of metallic structures to avoid catastrophic failures. The proposed crack sensing system consists of a dielectric substrate with a ground plane on one side of the substrate and an antenna patch printed on the other side of the substrate. The ground plane and the antenna patch, both conductive in nature, form an electromagnetic resonant cavity that radiates at distinct frequencies. These frequencies are monitored to evaluate the condition of cracks. A wireless sensor array can be realized by implementing a wireless interrogation unit. The scientific merits of this research are: 1) high sensitivity: it was demonstrated that the antenna sensors can detect crack growth with a sub-millimeter resolution; 2) passive wireless operation: based on microstrip antennas, the antenna sensors encode the sensing information in the backscattered antenna signal and thus can transmit the information without needing a local battery; 3) thin and conformal: the entire sensor unit is less than a millimeter thick and highly conformal; 4) crack orientation detection: the crack orientation on the structure can be precisely evaluated based on a single parameter, which only few sensors can accomplish. In addition to crack detection, the patch antenna sensors are also investigated for measuring shear and pressure forces, with an aim to study the formation, diagnostics and prevention of foot ulcers in diabetic patients. These sensors were vertically integrated and embedded in the insole of shoes for measuring plantar pressure/shear distribution. The scientific merits of this proposed research are: 1) simultaneous shear/pressure measurement : current smart shoe technology can only measure shear and pressure separately due to the size of the shear sensor. The proposed sensor can measure shear and pressure deformation simultaneously; 2) high sensitivity and spatial resolution: these sensors are very sensitive and have compact size that enables measuring stress distribution with fine spatial resolution; 3) passive and un-tethered operation: the sensor transponder was mounted on the top surface of the shoe to facilitate wireless interrogation of the sensor array embedded in the insole of the shoe, eliminating external wiring completely.

Mohammad, Irshad

414

Fusion of conformal interfaces  

Microsoft Academic Search

We study the fusion of conformal interfaces in the c = 1 conformal field theory. We uncover an elegant structure reminiscent of that of black holes in supersymmetric theories. The role of the BPS black holes is played by topological interfaces, which (a) minimize the entropy function, (b) fix through an attractor mechanism one or both of the bulk radii,

C. Bachas; I. Brunner

2008-01-01

415

Crime and Conformism  

Microsoft Academic Search

We propose a simple conformism model that explains how parental education and peer pressure impact on criminal activities. We then test the model using the U.S. National Longitudinal Survey of Adolescent Health (AddHealth), which contains unique information on friendship relationships among delinquent teenagers. We find that conformity is very strong within groups of delinquents and that the higher the taste

Eleonora Patacchini; Yves Zenou

2005-01-01

416

CONSENSUS AND CONFORMITY.  

ERIC Educational Resources Information Center

|IN THIS STUDY, PROFESSOR ALLEN EMPLOYS TWO METHODS OF BREAKING GROUP CONSENSUS, AND HE MEASURES THE EFFECTS ON THE RESPONSES OF COLLEGE SUBJECTS TO BOTH OBJECTIVE AND SUBJECTIVE STIMULI. THE RESULTS SUGGEST THE NEED FOR MODIFICATION OF EXISTING THEORIES OF CONFORMITY BEHAVIOR. IN ADDITION, THESE RESULTS EMPHASIZE THE DIFFERENCES IN CONFORMITY OF…

ALLEN, VERNON L.; LEVINE, JOHN M.

417

Structure and Conformation of Carbohydrates  

NASA Astrophysics Data System (ADS)

The conformational analysis of monosaccharides, disaccharides, and oligosaccharides is reviewed. Conformational terms are introduced through examination of the conformations of cyclohexane and cyclopentane then applied to the pyranose, furanose , and septanose rings. Concepts such as the anomeric effect are discussed. Topics of current interest, such as hydroxymethyl group and hydroxyl group rotation and disaccharide conformations are summarized. Physical methods for studying conformation are outlined.

Grindley, T. Bruce

418

Conformational studies on parathion  

NASA Astrophysics Data System (ADS)

Theoretical conformational studies have been carried out at the density functional theory (DFT) level on parathion (O,O-diethyl-O-p-nitrophenyl phosphorothioate), to correlate the conformational properties of this molecule with its biological activity. Different conformers of parathion have been taken into account, and the accuracy of our theoretical approach has been gauged against the results of the second-order Møller-Plesset perturbation calculations. The aqueous solvation of these molecules has been studied at the DFT level, using a polarized continuum model (PCM) with a conductor-like screening reaction field approach. The results show that parathion has high conformational flexibility in the gas phase, as well as in an aqueous medium, and the barriers to transition to different low-energy conformers are thermally allowed. The molecular electrostatic potential surfaces of the various low-energy conformers of this molecule have been compared with the related non-aged enzyme-bound organophosphorus structure to investigate the role of the calculated conformers on the biological activity of this molecule.

Ford-Green, Jason; Majumdar, D.; Leszczynski, Jerzy

419

The Radiation Resistance of Beam Antennas  

Microsoft Academic Search

In this paper a new method proposed by Brillouin for the calculation of radiation resistance is applied to several types of beam antennas. New formulas are deduced and some interesting results are obtained showing the distribution of the radiated power among the different wires of beam antennas and giving the numerical value of the radiation resistance in various cases (synphase

A. A. Pistolkors

1929-01-01

420

Static analysis of synchronism deployable antenna  

Microsoft Academic Search

A 3-dimensions synchronism deployable antenna had been designed, analyzed, and manufactured by our research group. This antenna consists of tetrahedral elements from central element. Because there are springs at the ends of some of the rods, spider joints are applied. For analysis purpose, the structure is simplified and modeled by using two dimensional beam elements that have no bending stiffness.

Fuling Guan; SHOU Jian-jun; Jingjie Zhang

2006-01-01

421

Low Sidelobe Phased Array Antenna System.  

National Technical Information Service (NTIS)

In a pulse radar system, wide angle sidelobes are reduced considerably in a phased array antenna by advancing each digital phase shifter by one bit just before each radar pulse is transmitted. This advance maintains the linear phase slope of the antenna e...

A. E. Blume

1982-01-01

422

GPS Digital Phased Array Antenna and Receiver.  

National Technical Information Service (NTIS)

NAVSYS High Gain Advanced GPS Receiver (HAGR) uses a digital beam- steering antenna array to enable up to eight GPS satellites to be tracked, each with up to 10 dBi of additional antenna gain over a conventional receiver solution. This digital, PC-based a...

A. Brown R. Silva

2000-01-01

423

Analysis of microstrip antennas using moment methods  

Microsoft Academic Search

The method of moments is used to analyze microstrip antennas of rectangular and nonrectangular shape. Surface currents are used to model the microstrip patch and volume polarization currents for the dielectric slab. The method requires unusually precise computation of the impedance matrix but is capable of accurately predicting currents, impedance, and resonant frequency of the antenna.

E. H. Newman; P. Tulyathan

1981-01-01

424

Ultra wideband antenna design for implant applications  

Microsoft Academic Search

Wireless telemetry based secure communication has been extensively worked to improve the life quality of patients having heart problems, diabetic problems and so on. Information of appropriate biosensors could be transferred via implant antennas to which, there are a growing research interests. In the scope of this work, we have designed a wide band antenna for biotelemetry communication. Radiation diagram,

F. Zengin; B. Turetken; E. Akkaya; S. E. San

2010-01-01

425

A UHF wide-band SAR antenna  

Microsoft Academic Search

This UHF wideband antenna was developed for DARPA's synthetic aperture radar (SAR) applications. The small array could be mounted at the belly of an aircraft. The operating frequency covers a 4:1 bandwidth. The antenna including the feed and a contoured ground plane was designed to fit in a shallow radome (50 cm×100 cm×100 cm). The depth of the radome is

J. J. Lee; S. Livingston; G. Sauer; G. Crandall

2000-01-01

426

Wideband Slot Antenna for WLAN Access Points  

Microsoft Academic Search

This letter presents a new printed slot antenna with cavity back for WLAN Access Points (Base Stations) providing wideband operation bandwidth at least from 2.5 to 4.8 GHz. The design is based upon an ultrawideband antenna configuration modified with the inclusion of a cavity back in order to produce stable unidirectional radiation pattern. The new configuration also ensures a stable

Carla R. Medeiros; Jorge R. Costa; Carlos A. Fernandes

2010-01-01

427

The ITER ICRF Antenna Design with TOPICA  

NASA Astrophysics Data System (ADS)

TOPICA (Torino Polytechnic Ion Cyclotron Antenna) code is an innovative tool for the 3D/1D simulation of Ion Cyclotron Radio Frequency (ICRF), i.e. accounting for antennas in a realistic 3D geometry and with an accurate 1D plasma model [1]. The TOPICA code has been deeply parallelized and has been already proved to be a reliable tool for antennas design and performance prediction. A detailed analysis of the 24 straps ITER ICRF antenna geometry has been carried out, underlining the strong dependence and asymmetries of the antenna input parameters due to the ITER plasma response. We optimized the antenna array geometry dimensions to maximize loading, lower mutual couplings and mitigate sheath effects. The calculated antenna input impedance matrices are TOPICA results of a paramount importance for the tuning and matching system design. Electric field distributions have been also calculated and they are used as the main input for the power flux estimation tool. The designed optimized antenna is capable of coupling 20 MW of power to plasma in the 40 -- 55 MHz frequency range with a maximum voltage of 45 kV in the feeding coaxial cables. [1] V. Lancellotti et al., Nuclear Fusion, 46 (2006) S476-S499

Milanesio, Daniele; Maggiora, Riccardo; Meneghini, Orso; Vecchi, Giuseppe

2007-11-01

428

Human exposure to cellular base station antennas  

Microsoft Academic Search

The human exposure to RF power radiated by cellular base station antennas can be assessed by means of the incident power density averaged over the body. The convenience of adopting this quantity lies in its well-behaved decay away from the antenna. As a consequence, the average power density decay can be predicted using simple formulas, which remain valid even in

Quirino Balzano; Antonio Faraone

1999-01-01

429

47 CFR 15.203 - Antenna requirement.  

Code of Federal Regulations, 2012 CFR

...The manufacturer may design the unit so that a broken antenna can be replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited. This requirement does not apply to carrier current devices or to devices...

2012-10-01

430

Polarimetric SAR (Synthetic Aperture Radar) Antenna Characterization.  

National Technical Information Service (NTIS)

A procedure is described for obtaining the two-way polarimetric properties of a Synthetic aperture radar (SAR) antenna from one-way measurements in a compact antenna test range. The two-way properties are determined by involving reciprocity and computing ...

R. M. Barnes D. J. Blejer

1989-01-01

431

Lens-type compact antenna range  

Microsoft Academic Search

A compact antenna range is described which uses a plastic foam lens to obtain a collimated beam within which the radiation pattern of a test antenna can be measured. A novel feature is the introduction of a controlled amount of loss into the lens so that a nearly uniform electric field is measured over a high proportion of the lens

A. D. Olver; A. A. Saleeb

1979-01-01

432

Analysis of compact antenna test range configurations  

Microsoft Academic Search

An antenna test center for antennas and payloads of large spacecraft was constructed. It consists of a near field and a compact test range. Results obtained during the analysis and definition phase of the compact range are described. Predicted co- and cross-polar contour plots of different compact range alternatives in the 5m x 7m quiet zone are presented. Compensation and

E. W. M. Dudok; D. Fasold

1986-01-01

433

A pragmatic approach to adaptive antennas  

Microsoft Academic Search

This paper presents a novel approach for efficient computation of adaptive weights in phased-array antennas. The fundamental philosophical differences between adaptive antennas and adaptive signal-processing methodology are also delineated. This approach, unlike the conventional statistical techniques, eliminates the requirement for an interference covariance matrix, and represents a rethinking of the entire conventional approach to adaptive processing. This approach provides greater

Tapan K. Sarkar; Jinwan Koh; Raviraj Adve; Richard A. Schneible; Michael C. Wicks; Seungwon Choi; Magdalena Salazar Palma

2000-01-01

434

Measurement uncertainties in automotive antenna measurements  

Microsoft Academic Search

For the validation of an open area test site usually the normalized site attenuation (NSA) is considered. However, the model for the calculation of the NSA in the various standards is a point dipole. While this may be a correct assumption for biconical antennas or reference dipoles with a well-defined phase center, it is wrong for the antennas used in

Christoph Ullrich; Hicham Tazi

2010-01-01

435

Telecommunications antennas for the Unisat 1 satellite  

Microsoft Academic Search

The elliptical paraboloidal reflector fed by elliptical corrugated horn, the elliptical paraboloidal reflector fed by a horn cluster, and the distorted paraboloidal reflector fed by a conical corrugated horn are examined as potential antenna designs for the Unisat 1 telecommunications satellite. The reflector profile distortions and the illumination of the service areas are calculated using the array antenna radiation pattern

C. B. Wyllie; A. D. Monk

1985-01-01

436

DESIGN CONSIDERATIONS FOR INTEGRATED MOBILE PHONE ANTENNAS  

Microsoft Academic Search

In this paper some of these relations will be discussed. Based on these design guidelines a concept for a GShUDCSPCS antenna suitable for the integration into a mobile will be resented. The investigation is carried out using EMPIRE which IS a commercial FDTD software from IMST GmbH. Interaction of the antenna with the board

D. Manteuffel; A. Bahr; D. Heberling; I. Wolff

2009-01-01

437

Novel photonically controlled antenna for MMW communications  

Microsoft Academic Search

We describe a new optically-controlled, narrow beam antenna for point to point communications. A computer controlled light source photo-injects a spatially varying plasma into a photoconducting wafer for MMW beam control. Antennas based on this approach are inexpensive and offer many advantages

George W. Webb; Susan Angello; Wayne Vernon; Mario S. Sanchez; Stephen C. Rose

2000-01-01

438

Analysis of microstrip photonic bandgap antennas  

Microsoft Academic Search

The ever increasing developments in telecommunication systems have demanded a great deal of miniaturization process in the circuits that compose these systems Micrometer size antennas are very useful in the implementation of antenna arrays, and due to their reduced size is very appropriate for the use in catheters for example. The prospects of using frequencies in the terahertz range, opens

H. C. C. Fernandes; L. P. Rodrigues; K. M. B. de Oliveira

2001-01-01

439

Novel photonically-controlled reflectarray antenna  

Microsoft Academic Search

A novel method for generating a reconfigurable reflectarray based on the creation of photoinduced plasma inside the semiconductor substrate of a reflectarray is presented in this paper. A reflectarray antenna prototype is fabricated and measured to demonstrate the validity of the design methodology. Measurements were carried out to characterize the bandwidth and the gain of the antenna in both the

Mohammad Reza Chaharmir; Jafar Shaker; Michel Cuhaci; Abdel-Razik Sebak

2006-01-01

440

Photonic Antenna Reconfiguration: A Status Survey  

Microsoft Academic Search

The primary focus of photonics for antenna systems has, historically, been on the development of link and beam steering techniques. More recent work is focusing on the design of new types of antenna elements or arrays of elements to take advantage of the advances in photonics. By using photonically controlled devices and materials it is possible to produce revolutionary changes

Michael L. VanBlaricum

441

Photonic antenna reconfiguration: a status survey  

Microsoft Academic Search

The primary focus of photonics for antenna systems has, historically, been on the development of link and beam steering techniques. More recent work is focusing on the design of new types of antenna elements or arrays of elements to take advantage of the advantages in photonics. By using photonically controlled devices and materials and materials it is possible to produce

Michael L. van Blaricum

1998-01-01

442

High-directivity photonic bandgap antenna  

Microsoft Academic Search

The microstrip patch antenna is a low-profile low cost robust planar structure. A wide practical range of can be obtain with this type of antenna and, due to the ease of manufacture, is inexpensive compared with other types of operation, low gain, and a potential decrease in radiation efficiency due do surface-wave losses. In this paper, a new type of

Yuan Li; Huancai Li; Yuanchao Wang; Jie Jin

2004-01-01

443

Simulating Photonic Bandgap Antennas on Silicon Substrate  

Microsoft Academic Search

With the idea of having antennas on chip, this paper describes an implementation of a micro antenna fabricated on a silicon substrate in order to have uniformity in fabrication steps that will help bring down cost of manufacturing and efficiency of design. We have also looked into the field of photonic or electromagnetic bandgap (PBG\\/EBG) structures to increase the efficiency

N. Haridas; A. T. Erdogan; A. J. Walton; T. Arslan

2006-01-01

444

Small multiband antenna for personal communications devices  

Microsoft Academic Search

The advent of new, multistandard mobile phone devices is a real challenge for antenna designers, as they have to implement integrated multiband within a volume, which is rapidly shrinking. In this paper, some investigations concerning the input return loss and current distributions of a novel internal, quadband patch antenna are presented.

M. Martinez-Vazquez; Oliver Litschke

2003-01-01

445

ESTEC Mini Compact Antenna Test Range.  

National Technical Information Service (NTIS)

The ESTEC Mini Compact Antenna Test Range (Mini CATR) facility makes it possible to test full size antennas (up to 1.5 m) indoors in a relatively small space. A dual reflector system produces an incident plane wave so that the far field results are obtain...

1987-01-01

446

Wide-band planar monopole antennas  

Microsoft Academic Search

The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency

Narayan Prasad Agrawall; Girish Kumar; K. P. Ray

1998-01-01

447

Phased array antenna with temperature compensating capability  

Microsoft Academic Search

Generally, a variation of temperature at the installation site causes a phased array antenna radiation pattern to degrade. This paper describes the temperature characteristics of various components of the phased array antenna and degradations of the radiation pattern originating from temperature variations. It is effective to measure the phase distribution on the aperture and correct it, as the occasion demands,

Y. Kuwahara

1996-01-01

448

A method for determining antenna phase center  

Microsoft Academic Search

A holographic technique for the determination of antenna phase center is proposed. This center is found as the point of the intersection of normals retrieved from the centers of holograms recorded at an angle to one another. The proposed method is used to experimentally determine the phase center of a horn antenna.

Iu. I. Gridin; A. N. Lukin; I. F. Strukov

1990-01-01

449

Deep Monitoring Chandra Observations of The Antennae  

Microsoft Academic Search

The interacting pair of galaxies NGC 4038\\/39 (The Antennae), at a distance of 19 Mpc (H0 = 75), has been studied intensely at all wavelengths as the nearest example of galaxies undergoing a major merger. The Antennae provide a local laboratory where astronomers can easily observe phenomena that occur in the deeper Universe. There, merging is common and may be

G. Fabbiano; A. Baldi; A. Zezas; A. R. King; T. J. Ponman; J. Raymond; A. Read; A. Rots; F. Schweizer

2003-01-01

450

Structures for remotely deployable precision antennas  

NASA Astrophysics Data System (ADS)

Future space missions such as the Earth Science Geostationary Platform (ESGP) will require highly accurate antennas with apertures that cannot be launched fully formed. The operational orbits are often inaccessible to manned flight and will involve expendable launch vehicles such as the Delta or Titan. There is therefore a need for completely deployable antenna reflectors of large size capable of efficiently handling millimeter wave electromagnetic radiation. The parameters for the type of mission are illustrated. The logarithmic plot of frequency versus aperture diameter shows the regions of interest for a large variety of space antenna applications, ranging from a 1500-meter-diameter radio telescope for low frequencies to a 20-meter-diameter infrared telescope. For the ESGP, a major application is the microwave radiometry at high frequencies for atmospheric sounding. Almost all existing large antenna reflectors for space employ a mesh-type reflecting surface. Examples are shown and discussed which deal with the various structural concepts for mesh antennas. Fortunately, those concepts are appropriate for creating the very large apertures required at the lower frequencies for good resolution. The emphasis is on the structural concepts and technologies that are appropriate to fully automated deployment of dish-type antennas with solid reflector surfaces. First the structural requirements are discussed. Existing concepts for fully deployable antennas are then described and assessed relative to the requirements. Finally, several analyses are presented that evaluate the effects of beam steering and segmented reflector design on the accuracy of the antenna.

Hedgepeth, J. M.

1989-07-01

451

Null synthesis for shaped reflector antennas  

Microsoft Academic Search

Some preliminary results are presented, demonstrating the feasibility of synthesizing reflector profiles to produce deep nulls in the radiation pattern at prescribed angles while maintaining high gain levels at other prescribed angles. The synthesis technique can be applied to both shaped rigid and reconfigurable mesh reflector antennas. Experimental results for an 85 cm mesh reflector antenna at 10 GHz are

A. D. Monk; P. J. B. Clarricoats; Zhou Hai

1991-01-01

452

Microwave holographic metrology of large reflector antennas  

Microsoft Academic Search

A microwave holographic technique for the determination of amplitude and phase of the principal and cross-polarized aperture fields of large reflector antennas is described. The hologram formation process utilizes the elevation over azimuth scanning system normally associated with these antennas, and, in this respect, appears to be unique among other proposed methods of field probing. The present work describes the

J. Bennett; A. Anderson; P. McInnes; A. Whitaker

1976-01-01

453

Multi-Band Antenna System for AGILE.  

National Technical Information Service (NTIS)

The 150 MHz antenna has an impedance matching network attached to its base with a female Mini- gz a UHF connector on the radio side of the housing, as shown in Figures 6A and 66. The 150 MHz antennas matching network is in turn connected to the radio equi...

2002-01-01

454

Shipboard Antenna Pattern Inversion using Prony's Method.  

National Technical Information Service (NTIS)

Because far field antenna patterns can be expressed in terms of an exponential series of the spatial distribution of the source, they are candidates for Prony processing. Prony's method is used here to invert antenna pattern data to obtain the source dist...

J. C. Logan J. W. Rockway

1978-01-01

455

A UHF omni-directional RFID antenna  

Microsoft Academic Search

This paper has presented an omni-directional tag antenna for UHF item-level RFID applications. The RFID tag using the proposed antenna has exhibited a very good omni-directional reading pattern, which has shown great potential for item-level RFID applications in restaurants or libraries for tracking the items such as plates and books.

Kevin Tan Kaiwen; Xianming Qing; Chean Khan Goh; Lei Zhu

2010-01-01

456

A wide-angle scanning optical antenna  

Microsoft Academic Search

The design of a modified Rinehart metal dome antenna with a dielectric ring lens at the output edge is discussed. This antenna provides wide-angle scanning of a narrow beam. The dome shape, which provides perfect focus in the plane of scan, is determined by solving an integral equation. The dielectric lens focuses in the plane perpendicular to the plane scan,

E. C. Dufort; H. Uyeda

1983-01-01

457

Quasi-optical antennas for plasma scattering  

Microsoft Academic Search

Two types or quasi-optical antennas are examined for their suitability as a means of directing the radiation from a tunable gyrotron millimetre-wave source into a plasma for scattering. The first type of antenna has a single parabolic reflector. The second has two reflectors; the first elliptical, the second parabolic. This combination has the advantage of focusing the beam into a

G. F. BRAND; P. W. FEKETE; T. IDEHARA; K. J. MOORE

1990-01-01

458

Optical Antenna Effect in Semiconducting Nanowires  

Microsoft Academic Search

Using Raman scattering, we have observed strong optical antenna effects which we identify with internal standing wave photon modes of the wire. The antenna effects were probed in individual GaP NWs whose diameters are in the range 40

P. C. Eklund; Jian Wu; Qiujie Lu; H. R. Gutierrez; Qihua Xiong; M. E. Pellen; D. H. Werner

2008-01-01

459

Analysis of vibrating lightweight radar antennas  

Microsoft Academic Search

Future military aircraft and UAV's require the installation of lightweight and low-cost Electronically Steerable Antennas (ESA) which are needed by high-performance Airborne Moving Target Indicator and Surface Moving Target Indicator radars. When these antennas are integrated into the skin of air vehicles, they are subject to unsteady aerodynamic loads. Mechanical forces and these aerodynamic loads will cause deformation of the

Harmen Schippers; Guus Vos

2009-01-01

460

Modeling antenna close to the human body  

Microsoft Academic Search

Evaluation of antenna performance needs to be addressed in complex environments rather than in free space. There are many situations when such a need arises. We give examples of evaluation when a human body is in the close proximity of an antenna. In this case, it is also important to evaluate the power absorption in the body in terms of

Maria A. Stuchly; Mizanur Rahman; Michael Potter; Trevor Williams

2000-01-01

461

CSRH antenna control experiment and research  

NASA Astrophysics Data System (ADS)

We implemented the two-antenna synchronized control at short baseline distance (~8m) in the radio heliograph spectrometer test. In addition, we designed the scheme of two-antenna synchronized control at long baseline distance (~1km). The system control of radio heliograph spectrometer is also concerned.

Liu, Fei; Zhang, Jian; Chen, Zhi-Jun; Yan, Yi-Hua; Wang, Wei

2006-06-01

462

A New Type of Turnstile Antenna  

Microsoft Academic Search

This paper presents a new type of turnstile antenna, realized with two crossed dipoles connected in parallel. Feeding of the dipoles in phase quadrature to obtain an omnidirectional radiation pattern is achieved by optimizing their impedances to be complex conjugates. The dipoles are realized with aluminum strips. A balun - the transition from the antenna to a coaxial cable -

Ivana Radnovic; Aleksandar Nesic; Bratislav Milovanovic

2010-01-01

463

Millimeter wave corner reflector antenna array  

Microsoft Academic Search

In this paper we introduce new millimeter wave printed arrays with eight axially placed dipoles fed by a symphase network with the corner reflector. Three different typical beamwidths are investigated by a variation of the corner angle. Antennas are simulated and realized in the frequency range about 26 GHz which is popular for microwave communication networks. Three antennas are presented

A. Nesic; Z. Micic; S. Jovanovic; I. Radnovic; D. Nesic

2005-01-01

464

Wideband printed antenna with circular polarization  

Microsoft Academic Search

The paper presents a novel method of feeding of the single-feed printed antenna with circular polarization consisting of two orthogonal dipoles whose impedances are complexly conjugated thus obtaining quadrature feeding currents. A feeding line-balanced microstrip is placed perpendicularly to the antenna plate so that the parasitic coupling of the orthogonal dipoles and the feeding line is totally eliminated. In this

A. Nesic; S. Jovanovic; I. Radnovic

1997-01-01

465

Microstrip-antenna design for hyperthermia treatment of superficial tumors  

SciTech Connect

Microstrip antennas have many different advantages over other RF/MW radiative applicators employed for superficial hyperthermia treatment. This is mainly due to their compact and body-conformable structure as well as to printed circuit board techniques, both of which allow a wide design flexibility for superficial tumor heating. Among the wide variety of radiator configurations, three microstrip antennas of increasing complexity with electromagnetic and heating characteristics potentially suitable as applicators for superficial hyperthermia have been designed, developed, and tested in different radiative condition: a microstrip disk, a microstrip annular-slot, and a microstrip spiral. Electromagnetic design criteria are presented together with the determinations of the applicator return loss versus frequency and thermograms of the near-field heating pattern in muscle-like phantom. The results are in good agreement with theory and indicated that: the operating frequency is either single or multiple according to the applicator-mode, 'resonant' or 'traveling-wave', and can be chosen in the useful frequency range for hyperthermia according to the tumor cross-section and depth; the heating pattern flexibility increases going form the simple geometry disk to the annular-slot and spiral applicators; a distilled-water bolus is required; the annular-slot applicator exhibits the highest efficiency, while the spiral applicator provides the best performance.

Montecchia, F. (University of Ancona (Italy))

1992-01-01

466

Spinning conformal correlators  

NASA Astrophysics Data System (ADS)

We develop the embedding formalism for conformal field theories, aimed at doing computations with symmetric traceless operators of arbitrary spin. We use an indexfree notation where tensors are encoded by polynomials in auxiliary polarization vectors. The efficiency of the formalism is demonstrated by computing the tensor structures allowed in n-point conformal correlation functions of tensors operators. Constraints due to tensor conservation also take a simple form in this formalism. Finally, we obtain a perfect match between the number of independent tensor structures of conformal correlators in d dimensions and the number of independent structures in scattering amplitudes of spinning particles in ( d + 1)-dimensional Minkowski space.

Costa, Miguel S.; Penedones, João; Poland, David; Rychkov, Slava

2011-11-01

467

Sinuous antennas for cosmic microwave background polarimetry  

NASA Astrophysics Data System (ADS)

We are developing antenna-coupled Transition Edge Sensor (TES) bolometers to be used in the focal planes of telescopes mapping Cosmic Microwave Background (CMB) polarization anisotropies. These detectors will be both dual-polarized and ultra-wide band, each containing several frequency channels. Arrays of such detectors could realize mapping speeds nearly an order of magnitude higher than previously deployed technology while naturally facilitating foreground removal. For such detectors to be useful, the antennas must have a high gain and a low cross-polarization. We have designed a novel modification of DuHamel's Sinuous antenna that couples to a contacting lens and is driven by integrated microstrip feed-lines. The integrated feed lines allow the antenna to interface with microstrip circuits and bolometers in a way that is planar and scalable to kilo-pixel arrays. We have demonstrated the polarization and beam properties with scale model antennas that operate at 1-12 GHz.

O'Brient, Roger; Edwards, Jennifer; Arnold, Kam; Engargiola, Greg; Holzapfel, William; Lee, Adrian T.; Myers, Michael; Quealy, Erin; Rebeiz, Gabriel; Richards, Paul; Spieler, Helmuth; Tran, Huan

2008-08-01

468

Broadband circularly-polarized spidron fractal antenna  

US Patent & Trademark Office Database

A broadband circularly-polarized spidron fractal antenna is disclosed. The broadband antenna of the present invention can realize a bandwidth exceeding 70% without using a multilayer substrate to implement the broadband properties, by forming a geometric structure of a slot, i.e., a spidron fractal, which has not been used in the conventional antennas, on the ground surface of the antenna. The present invention can also induce the radiation properties of a circularly-polarized wave from the properties of the spidron fractal shape, without employing an additional secondary circuit such as a phase distribution circuit for implementing the circularly-polarized wave. Due to such properties described above, the present invention can implement a small broadband circularly-polarized antenna that costs less to manufacture.

Hwang; Keum-Cheol (Seoul, KR)

2012-08-21

469

Dual-mode antenna design for microwave heating and noninvasive thermometry of superficial tissue disease.  

PubMed

Hyperthermia therapy of superficial skin disease has proven clinically useful, but current heating equipment is somewhat clumsy and technically inadequate for many patients. The present effort describes a dual-purpose, conformal microwave applicator that is fabricated from thin, flexible, multilayer printed circuit board (PCB) material to facilitate heating of surface areas overlaying contoured anatomy. Preliminary studies document the feasibility of combining Archimedean spiral microstrip antennas, located concentrically within the central region of square dual concentric conductor (DCC) annular slot antennas. The motivation is to achieve homogeneous tissue heating simultaneously with noninvasive thermometry by radiometric sensing of blackbody radiation from the target tissue under the applicator. Results demonstrate that the two antennas have complimentary regions of influence. The DCC ring antenna structure produces a peripherally enhanced power deposition pattern with peaks in the outer corners of the aperture and a broad minimum around 50% of maximum centrally. In contrast, the Archimedean spiral radiates (or receives) energy predominantly along the boresight axis of the spiral, thus confining the region of influence to tissue located within the central broad minimum of the DCC pattern. Analysis of the temperature-dependent radiometer signal (brightness temperature) showed linear correlation of radiometer output with test load temperature using either the spiral or DCC structure as the receive antenna. The radiometric performance of the broadband Archimedean antenna was superior compared to the DCC, providing improved temperature resolution (0.1 degree C-0.2 degree C) and signal sensitivity (0.3 degree C-0.8 degree C/degree C) at all four 500 MHz integration bandwidths tested within the frequency range from 1.2 to 3.0 GHz. PMID:11077744

Jacobsen, S; Stauffer, P R; Neuman, D G

2000-11-01

470

Optimal antenna spacings in interferometric SAR  

NASA Astrophysics Data System (ADS)

In practice, a synthetic aperture radar (SAR) reconstructs the complex reflectivity function of a scene, modulated by phase terms that capture 3-D imaging geometry. INSAR (interferometric SAR) attempts to obtain the geometric information by interfering two images (from two antennas) to cancel the same scene reflectivity and recover the scene topography transduced by the image-phase data. This approach, however, leads to a phase-unwrapping problem, which causes ambiguities in estimates of elevation. The phase-unwrapping problem can be solved in a pointwise fashion by using more than two antennas. This approach can effectively prevent error propagation which occurs in traditional phase-unwrapping algorithms. In this work, we study the optimal antenna spacings for pointwise terrain height estimation. In particular, we start from the maximum likelihood estimates of the phase using neighborhood pixels collected by any pair of antennas. The phase estimation noise is approximated as Gaussian with variance prescribed by the Cramer-Rao lower bound on the phase estimate. The ambiguous terrain height derived from any pair of antennas is modeled by a periodic waveform with each period having an approximately Gaussian shape. For multiple pairs of antennas, the corresponding functions describing the ambiguous elevation have different periods, which acts to help resolve the ambiguity. We derive and analyze the ML estimate of elevation at each scene point using multiple pairs of antennas. For the three-antenna case, by analyzing the tradeoff between cycle errors and measurement errors, a closed-form formula approximating the mean squared error (MSE) of the estimated terrain height is derived as a function of antenna spacing. By minimizing the MSE, we determine the optimal antenna spacing. The algorithm is tested with simulated data.

Xiao, Shu; Munson, David C.

2000-08-01

471

Conformational Characteristics of Polystyrene.  

National Technical Information Service (NTIS)

Conformational energies of meso and racemic dyads of polystyrene have been computed as functions of skeletal bond rotations. Confinement of rotations of the phenyl groups to a small range within which they are nearly perpendicular to the plane defined by ...

D. Y. Yoon P. R. Sundararajan P. J. Flory

1975-01-01

472

First two ALMA antennas successfully linked  

NASA Astrophysics Data System (ADS)

Scientists and engineers working on the world's largest ground-based astronomical project, the Atacama Large Millimeter/submillimeter Array (ALMA), have achieved another milestone -- the successful linking of two ALMA astronomical antennas, synchronised with a precision of one millionth of a millionth of a second -- to observe the planet Mars. ALMA is under construction by an international partnership in the Chilean Andes. ESO PR Photo 18a/09 The two ALMA antennas On 30 April, the team observed the first "interferometric fringes" of an astronomical source by linking two 12-metre diameter ALMA antennas, together with the other critical parts of the system. Mars was chosen as a suitable target for the observations, which demonstrate ALMA's full hardware functionality and connectivity. This important milestone was achieved at the ALMA Operations Support Facility, high in Chile's Atacama region, at an altitude of 2900 metres. "We're very proud and excited to have made this crucial observation, as it proves that the various hardware components work smoothly together. This brings us another step closer to full operations for ALMA as an astronomical observatory," says Wolfgang Wild, the European ALMA Project Manager. The two antennas used in this test will be part of ALMA's array of 66 giant 12-metre and 7-metre diameter antennas that will observe in unison as a single giant telescope, under construction on the Chajnantor plateau above the Operations Support Facility, at an altitude of 5000 metres. ALMA will operate as an interferometer, capturing millimetre and submillimetre wavelength signals from the sky with multiple antennas, and combining them to create extremely high resolution images, similar to those that would be obtained by a single, giant antenna with a diameter equal to the distance between the antennas used. "This can only be achieved with the perfect synchronisation of the antennas and the electronic equipment: a precision much better than one millionth of a millionth of a second between equipment located many kilometers apart. The extreme environment where the ALMA observatory is located, with its strong winds, high altitude, and wide range of temperatures, just adds to the complexity of the observatory and to the fascinating engineering challenges we face", comments Richard Murowinski, ALMA Project Engineer. The astronomical target in this scientific milestone was the planet Mars. The astronomers measured the distinctive "fringes" -- a regular pattern of alternating strong and weak signals -- detected by the interferometer as the planet moved across the sky. The hardware used in this successful first test included two 12-metre diameter ALMA antennas as well as the complex series of electronic processing components needed to combine the signals. Such pairs of antennas are the basic building blocks of imaging systems that enable radio telescopes to deliver pictures that approach or even exceed the resolving power of visible light telescopes. Each antenna is combined electronically with every other antenna to form a multitude of antenna pairs. Each pair contributes unique information that is used to build a highly detailed image of the astronomical object under observation. When completed in early in the next decade, ALMA's 66 antennas will provide over a thousand such antenna pairings, with distances between antennas up to 16 kilometres. This will enable ALMA to see with a sharpness surpassing that of the best space telescopes, and to complement ground-based optical interferometers such as the ESO Very Large Telescope Interferometer (VLTI). "We are on target to do the first interferometry tests at the 5000-metre high-altitude site by the end of this year, and by the end of 2011 we plan to have at least 16 antennas working together as a single giant telescope," said Thijs de Graauw, ALMA Director. Notes for editors ALMA is a revolutionary astronomical telescope, comprising an array of 66 giant 12-metre and 7-metre diameter antennas observing at millimetre and submi

2009-05-01

473

Enhancing molecule fluorescence with asymmetrical plasmonic antennas  

NASA Astrophysics Data System (ADS)

We propose and justify by the finite-difference time-domain method an efficient strategy to enhance the spontaneous emission of a fluorophore with a multi-resonance plasmonic antenna. The custom-designed asymmetrical antenna consists of two plasmonic nanoparticles with different sizes and is able to couple efficiently to free space light through multiple localized surface plasmon resonances. This design simultaneously permits a large near-field excitation near the antenna as well as a high quantum efficiency, which results in an unusual and significant enhancement of the fluorescence of a single emitter. Such an asymmetrical antenna presents intrinsic advantages over single particle or dimer based antennas made using two identical nanostructures. This promising concept can be exploited in the large domain of light-matter interaction processes involving multiple frequencies.We propose and justify by the finite-difference time-domain method an efficient strategy to enhance the spontaneous emission of a fluorophore with a multi-resonance plasmonic antenna. The custom-designed asymmetrical antenna consists of two plasmonic nanoparticles with different sizes and is able to couple efficiently to free space light through multiple localized surface plasmon resonances. This design simultaneously permits a large near-field excitation near the antenna as well as a high quantum efficiency, which results in an unusual and significant enhancement of the fluorescence of a single emitter. Such an asymmetrical antenna presents intrinsic advantages over single particle or dimer based antennas made using two identical nanostructures. This promising concept can be exploited in the large domain of light-matter interaction processes involving multiple frequencies. Electronic supplementary information (ESI) available: The performance of plasmonic enhanced one-photon fluorescence within the nanogap of symmetrical optical antennas, i.e. Rods-L45-L45 and Rods-L60-L60 are formed by end to end coupling the Rod-L45 and Rod-L60 antennas separately; and the performance of plasmonic enhanced two-photon fluorescence by coupling the Rods-L50-L50 and Rods-L70-L70 antennas for comparison. See DOI: 10.1039/c3nr01306e

Lu, Guowei; Liu, Jie; Zhang, Tianyue; Shen, Hongming; Perriat, Pascal; Martini, Matteo; Tillement, Olivier; Gu, Ying; He, Yingbo; Wang, Yuwei; Gong, Qihuang

2013-06-01

474

Volumetric pattern analysis of fuselage-mounted airborne antennas  

Microsoft Academic Search

A volumetric pattern analysis of fuselage-mounted airborne antennas at high frequencies was investigated. The primary goal of the investigation was to develop a numerical solution for predicting radiation patterns of airborne antennas in an accurate and efficient manner. An analytical study of airborne antenna pattern problems is presented in which the antenna is mounted on the fuselage near the top

C. L. Yu

1976-01-01

475

Merging reconfigurable and deployable antennas for space applications  

Microsoft Academic Search

This paper discusses the merging potential of reconfigurable and deployable antennas for more efficient holistic designs suited for space applications. In this paper we review physically reconfigurable and deployable antennas and present a new concept for a physically reconfigurable deployable log-periodic structure. This antenna is designed to cover UHF frequencies for space communications. The control of such antennas using software

J. Costantine; Y. Tawk; C. G. Christodoulou; S. E. Barbin; J. Banik

2011-01-01

476

An accurate moment method model for the tapered slot antenna  

Microsoft Academic Search

A moment-method model is presented for the radiation characteristics of the tapered slot antenna. It overcomes the shortcoming of an earlier theory. The method is rigorous for the air dielectric antennas. For dielectric-supported antennas, the method is approximate but accurate. The method is particularly accurate for antennas etched on substrates that are electrically thin or have a low dielectric constant,

Ramakrishna Janaswamy

1989-01-01

477

COMPACT M-SLOT FOLDED PATCH ANTENNA FOR WLAN  

Microsoft Academic Search

Abstract—This paper presents a very small size microstrip antenna suitable for WLAN application. The main patch antenna consists of an M-shaped slot with shorting wall. With a shorted triangular parasitic patch and a folded patch overall antenna size is reduced. The simulated and measured results show that by selecting a proper shorting wall width, the proposed antenna can provide an

Farid Jolani; Abdolmhdi M. Dadgarpour; Hamid Reza Hassani

2008-01-01

478

A new antenna selection scheme for correlated MIMO channels  

Microsoft Academic Search

To reduce the severe performance degradation of the traditional antenna selection schemes in correlated channels, this paper proposes a new antenna selection scheme via the self-organizing feature map (SOFM) algorithm which exploits spatial local related statistical information in fully correlated channels to improve the spatial adaptability. SOFM algorithm classifies N available antennas into L classes: antennas in each class are

Jianxin Dai; Ming Chen

2010-01-01

479

Characteristics of wideband ring loop antenna for digital terrestrial broadcasting  

Microsoft Academic Search

In the transmitting and receiving antenna for the UHF band broadcasting, the requirements of the antenna are wideband linear polarization characteristics. It is possible to make a wideband antenna using the loop antenna, arranged vertically, with a circumference length about one wavelength. Miniaturization becomes possible in a simple shape by the realization of a wideband and high-gain linearly polarized ring

H. Kawakami; T. Haga; S. Kon

2005-01-01

480

Wideband circularly polarized rhombic loop antennas with different feed models  

Microsoft Academic Search

Two types of circularly polarized linear antenna having a rhombic loop configuration are investigated. One type of circularly polarized antenna is a single feed dual rhombic loop antenna (DRLA). The DRLA consists of two rhombic loops of the same size and is located above an infinite ground plane. The other is a hula hoop antenna (HHA). The HHA is fed

H. Morishita; T. Iizuka; K. Himsawa; T. Nagao

1995-01-01

481

Design and realization of base station antenna for mobile communication  

Microsoft Academic Search

In this paper, we design and realize a type of dual-polarization base station antenna on the basis of an L-strip patch antenna for mobile communication. To improve the polarization isolation of the antenna, a novel scheme is proposed which uses the two adjacent units to counteract the coupled components. In order to allow the antenna's vertical pattern to accord with

Wang Chunhua; Lin Deyun; Shi Changsheng

2002-01-01

482

Multiband base station antenna for diversity and MIMO-applications  

Microsoft Academic Search

In this paper an antenna element for the application in multi band base station antennas for mobile communication systems is presented. The antenna element covers the most important frequency bands in Europe and Asia (GSM 1800, UMTS at 2100 GHz and UMTS-Plus at 2600 MHz), respects important features regarding manufacturing, signal distribution and signal intermodulation. Since the antenna can be

Florian Pivit; Georg Fischer; C. Waldschmidt; Werner Wiesbeck

2004-01-01

483

Boundary element modeling of radio base station antennas  

Microsoft Academic Search

The paper presents an accurate and efficient boundary element procedure for the analysis of radiation from base station antennas. The base station antenna system is represented by the vertical antenna array in front of perfectly conducting (PEC) ground plane reflector.The formulation of the problem is based on a set of coupled Pocklington integro-differential equations for vertical antenna array. This set

Dragan Poljak; Vicko Doric; Damir Vucicic; C. A. Brebbia

2006-01-01

484

Antenna Pattern Correction Technique Based on an Adaptive Array Algorithm  

Microsoft Academic Search

An antenna pattern correction technique is presented that is based on an adaptive array algorithm. In the method, the antenna pattern of the antenna under test (AUT) is measured several times at different positions in the quiet-zone. The corrected antenna pattern is obtained by taking a weighted average of the measured patterns. An array synthesis algorithm is employed for obtaining

Ville Viikari; Veli-Matti Kolmonen; Jari Salo; Antti V. Raisanen

2007-01-01

485

A dual port wide-narrowband antenna for cognitive radio  

Microsoft Academic Search

An antenna for cognitive radio application is presented in this paper. The structure is a novel combination of wideband and narrowband antennas into the same volume. The wideband antenna is a CPW fed printed hour-glass shaped monopole which operates from 3 to 11 GHz. The narrowband antenna is a microstrip patch printed on the reverse side of the substrate, and

Elham Ebrahimi; Peter S. Hall

2009-01-01

486

Pattern, gain and temperature measurements of reflector antennas  

Microsoft Academic Search

The authors present an overview of results for far field pattern, antenna gain, and antenna temperature measurements of reflector antennas in several frequency bands. The pattern and gain measurements were taken in the compact range at the Ohio State University. In a series of related measurements an 8 ft diameter Cassegrain reflector was used for antenna temperature measurements under clear

R. C. Rudduck; T.-H. Lee; K. M. Lambert

1990-01-01

487

Restoring antenna pointing initialization redundancy for TDRS-A  

Microsoft Academic Search

Spacecraft A of the Tracking and Data Relay Satellite System is currently on redundant equipment used in the pointing of the steerable antennas. The failed equipment is used to initialize the pointing software's knowledge of antenna position. Should there be a failure on the redundant side, one antenna could become inoperable. An antenna with such a failure could still be

Dennis J. Pugh

1989-01-01

488

Compact UltraShort Pulse Fuzing Antenna Design and Measurements  

Microsoft Academic Search

We consider here antennas that could be useful as part of a fuze radar for penetrating munitions. The concept requires radiating an ultra-short pulse using an antenna with maximum gain and a compact design. Both lens and reflector Impulse Radiating Antennas (IRAs) are recommended as suitable candidates for this purpose. We summarize the properties of these antennas, and we describe

Everett G. Farr; Charles A. Frost

489

Nontracking antenna performance for inertially controlled spacecraft using TDRSS  

Microsoft Academic Search

A series of tests to validate an antenna pointing concept for spin-stabilized satellites using a data relay satellite is described. These tests show that proper antenna pointing on an inertially stabilized spacecraft can lead to significant access time through the relay satellite even without active antenna pointing. We summarize the test results, the simulations to model the effects of antenna

STEPHEN HORAN

2003-01-01

490

Design of multi-band compact antennas for automotive communications  

Microsoft Academic Search

This paper presents the design of two different quad- band antennas for GSM\\/DCS\\/PCS communication equipment to be mounted inside vehicles (cars, trucks, …). The first solution is an antenna printed on a printed circuit board (PCB), thus reducing the cost virtually to zero, while the second solution is a three-dimensional patch antenna. Both antennas have been designed to be integrated

S. Arianos; G. Dassano; F. Vipiana; M. Orefice

2011-01-01

491

An ultra-lightweight high gain spacecraft antenna  

Microsoft Academic Search

A proof of concept telecommunications subsystem antenna (TSA) has been developed as part of the Pluto Fast Flyby Advanced Technology Insertion (ATI) program. The antenna was built to demonstrate the technology for an ultra-lightweight antenna which provides excellent RF performance. The Boeing antenna was designed to demonstrate the potential for significant weight reduction from the existing Viking 1.47 meter (58

W. A. Schneider; J. L. Moore; T. L. Blakney; D. D. Smith; J. D. Vacchione

1994-01-01

492

Broadband Uniplanar UHF Meander Line Antenna for Multistandard RFID Transponders  

Microsoft Academic Search

A broad band uniplanar antenna for passive UHF RFID tag applications is presented. The antenna has been designed to provide a multistandard transponder in one ISO 7810 ID-1 card with both the UHF meandered antenna and an ISO 15693 tag arranged in two separate sections. The broadband antenna is composed by a meander dipole and a loading bar electrically connected

A. Toccafondi; A. Cueing; F. Mariottini; P. Braconi

2007-01-01

493

Optimization of UHF RFID tag antennas using a genetic algorithm  

Microsoft Academic Search

UHF band (860~960 MHz) RFID tag strip-line antennas for non-metallic object and slotted patch RFID antenna for metallic objects have been optimized with a GA. The antennas are optimized for commercially available RFID tag IC chips. Different cell sizes of FDTD have been tried while the GA optimizes the symmetrical shape of RFID antennas

Goojo Kim; YouChung Chung

2006-01-01

494

Implanted antennas inside a human body: simulations, designs, and characterizations  

Microsoft Academic Search

Antennas implanted in a human body are largely applicable to hyperthermia and biotelemetry. To make practical use of antennas inside a human body, resonance characteristics of the implanted antennas and their radiation signature outside the body must be evaluated through numerical analysis and measurement setup. Most importantly, the antenna must be designed with an in-depth consideration given to its surrounding

Jaehoon Kim; Yahya Rahmat-Samii

2004-01-01

495

A standard shielded loop antenna with load resistor  

Microsoft Academic Search

A shielded loop antenna with a load resistor is presented in this paper. The simulated and experimental results have shown that it has very wide frequency bandwidth. This antenna can be used as a standard antenna to measure electronic or magnetic field strength. It also can be used to calibrate other measure antennas.

Yingqing Xia; Jia Luo; Huan Ye

2009-01-01

496

Miniaturized ENG ZOR antenna with high permeability material  

Microsoft Academic Search

The development of the antenna which has small size and broad bandwidth is the most important issue in wireless communication system. To reduce the size of an antenna, the epsilon negative (ENG) zeroth-order (ZOR) mushroom antenna which has unique property of an infinite wavelength wave at specific non-zero frequency was proposed. In this paper, the miniaturized ENG ZOR antenna having

Seung-Tae Ko; Jeong-Hae Lee

2010-01-01

497

Modified H-Shaped Antenna for Automotive Digital Terrestrial Reception  

Microsoft Academic Search

A modified H-shaped antenna is proposed for automotive digital terrestrial reception. The antenna is analyzed by the method of moments. The antenna has the feature that a figure-8 radiation pattern is rotated with increasing frequency. Four symmetrically mounted antennas at the top of the front and rear windows of a car have gain to the sides of the car as

Hideo Iizuka; Toshiaki Watanabe; Kazuo Sato; Kunitoshi Nishikawa

2005-01-01

498

Collapsible antennae deployed by electrostatic forces  

NASA Astrophysics Data System (ADS)

Conventional space mirror antennas occupy a substantial volume when folded; the dimensions of antennas, automatically extendable at orbit, may be reduced to magnitudes of about 100-200 m. These large mirror antennas are designed by means of thin films or mesh structures forming a reflecting surface, which are deployed by electrostatic forces. The interaction of charges applied to reflecting and subsidiary surfaces creates the electrostatic forces sustaining the structural form of the antenna. By varying the distribution of charges at the subsidiary shell, it is possible to change the structural form. Electrostatic forces in the shell must exceed outer influences, and the antenna should have a paraboloidal or spherical form and be made of soft materials, which can be extended by the forces of electrostatic charge interaction. Mirrors of considerable dimensions may be formed by combining a shell with stiffness rings; these rings are important factors defining the efficiency of the antenna, since they contribute to both the mass and the dimension of the antenna when packed.

Gvamichava, A. S.; Kotik, A. N.; Koshelev, V. A.; Nefedov, S. S.; Patsaeva, V. A.; Rogachev, A. S.; Sokolov, A. G.

1981-09-01

499

Truncated Icosahedral Gravitational Wave Antenna.  

NASA Astrophysics Data System (ADS)

A spherical gravitational wave detector can be equally sensitive to a wave from any direction, and also able to measure its direction and polarization. We derive a set of equations to describe the mechanics of a spherical antenna coupled to an arbitrary number of attached mechanical resonators. A special arrangement of 6 resonators is proposed, which we term a Truncated Icosahedral Gravitational Wave Antenna, or TIGA. An analytic solution to the equations of motion is found for this case. We find that direct deconvolution of the gravitational tensor components can be accomplished with a specified set of linear combinations of the resonator outputs, which we call the mode channels. We develop one simple noise model for this system and calculate the resulting strain noise spectrum. We conclude that the angle-averaged energy sensitivity will be 56 times better than for the typical equivalent bar-type antenna with the same noise temperature. We have constructed a prototype TIGA. This shape was machined from an Al 6063 cylindrical bar, is 84 cm in diameter, has its first quadrupole resonances near 3200 Hz, and is suspended from its center of mass. The frequencies of the lowest seven multiplets were found to closely match those calculated for a sphere. We observed the motion of the prototype's surface using 6 accelerometers attached to its surface in the symmetric truncated icosahedral arrangement. We have tested a first order direction finding algorithm, which uses fixed linear combinations of six accelerometer responses to first infer the relative amplitudes of the quadrupole modes and from these the location of the impulse. The six accelerometers were then replaced by six mechanical resonators. A strain gauge was used to monitor the radial motion of each resonator. The frequency response of the of coupled system was measured and compared to the eigenvalue solutions of the equations of motion. It was concluded that deviations from perfect symmetry have a second order effect on our ability to observe the prototype's quadrupole modes and thus determine the location and direction of the initial excitation.

Merkowitz, Stephen Michael

1995-01-01

500

Smart antenna technology for structural health monitoring applications  

NASA Astrophysics Data System (ADS)

A smart antenna has been developed for structural health monitoring. The antenna is based on Monarch's GEN 2 selfstructuring antenna (SSA) technology and provides polarization and beam-diversity for improving signal-to-noise ratio (SNR). The antenna works with University of Michigan's Narada platform, where a microcontroller monitors the RSSI and selects the best beam to maintain reliable RF link. Antenna has two wide beams for each polarization and the beams are selected by applying appropriate DC voltages to the RF switches on the antenna aperture. Paper presents the GEN C antenna, which is a smaller version of the GEN 2B with comparable performance features.

Özdemir, Tayfun; Goykhman, Yuriy; Oberdier, Larry; Lynch, Jerome

2010-03-01