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1

Metamaterial-based efficient electrically small antennas  

Microsoft Academic Search

A metamaterial paradigm for achieving an efficient, electrically small antenna is introduced. Spherical shells of homogenous, isotropic negative permittivity (ENG) material are designed to create electrically small resonant systems for several antennas: an infinitesimal electric dipole, a very short center-fed cylindrical electric dipole, and a very short coaxially-fed electric monopole over an infinite ground plane. Analytical and numerical models demonstrate

Richard W. Ziolkowski; Aycan Erentok

2006-01-01

2

Metamaterial-Inspired Efficient Electrically Small Antennas  

Microsoft Academic Search

Planar two-dimensional (2D) and volumetric three-dimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic-based EZ antennas are shown to be naturally matched to a 50 source, i.e., without the introduction of a

Aycan Erentok; Richard W. Ziolkowski

2008-01-01

3

Gain and bandwidth enhancement for a superconducting electrically small antenna  

NASA Astrophysics Data System (ADS)

We present a technique that enhances the gain of a superconducting electrically small antenna by manipulating the electromagnetic (EM) near-fields on the antenna aperture to increase the effective aperture area. The antenna has a conducting split ring and three parasitic T-shaped conducting structures to manipulate its EM near-fields. When the distribution of the EM near-fields becomes uniform, the effective aperture area increases, enhancing the antenna gain and bandwidth. The concept proposed in this study is applicable to a single electronically small antenna as well as to an element of an antenna array.

Wang, Ruixia; Wei, Bin; Cao, Bisong; Jiang, Linan

2015-04-01

4

Biologically-inspired, electrically small antenna arrays  

NASA Astrophysics Data System (ADS)

First, the motivation behind adding a passive external coupling network after antenna arrays is discussed, the concept of biomimetic antenna arrays (BMAAs) introduced and some of the previous work done in this area have been reviewed. Next, a BMAA which achieves an angular resolution of roughly 15 times its regular counterpart is introduced and fully characterized. The introduced BMAA employs transformers which considerably degrade its performance, namely its output power. To cicumvent this shortcoming a new architecture of a BMAA that does not employ transformers and therefore yields a higher output power for the same angular resolution has been subsequently presented. Moreover, a detailed noise analysis of this BMAA is carried out and the output noise of the new architecture is compared with the output noise of the original design. The modified twoelement BMAA architecture is then extended to multiple elements. A novel nonlinear optimization process is introduced that maximizes the total power captured by the BMAA for a given angular resolution and the concept illustrated for a three-element antenna array. Next an optimum two-element BMAA which achieves the maximum possible angular resolution while obtaining the same output power level of a regular antenna array with the same elements and spacing is introduced. A novel two-element superdirective array based on this optimum BMAA has been also discussed. The passive BMAAs discussed in this thesis have a relatively narrow bandwidth. To extend the bandwidth of BMAAs, non- Foster networks have been employed in their external coupling networks and it has been demonstrated that they can increase their bandwidth by a factor of roughly 33. Finally, the BMAA concept has been extended to nano-antenna arrays and a concept for designing sub-wavelength angle-sensing detectors at optical wavelengths has been introduced.

Masoumi, Amir Reza

5

A dual-band efficient metamaterial-inspired electrically-small magnetic-based antenna  

Microsoft Academic Search

This paper introduces a dual-band magnetic-based two-dimensional (2D) efficient metamaterial-inspired electrically-small antenna, i.e., a 2D dual-band magnetic-based EZ antenna. The combined 2D planar antenna system is naturally matched to the source at 900MHz and 1800MHz; and thus, it is an efficient radiator at these frequency bands. It will be shown that this antenna system acts as a resonant electrically-small magnetic

Aycan Erentok; Richard W. Ziolkowski

2007-01-01

6

An efficient, low profile, electrically small, three-dimensional, very high frequency magnetic EZ antenna  

NASA Astrophysics Data System (ADS)

A very high frequency version of the electrically small, coax-fed, three-dimensional magnetic EZ antenna was designed and tested. The fabricated antenna was formed by integrating a capacitively loaded loop element with a coaxially-fed, electrically small, semicircular loop antenna. This low profile antenna (height ˜?/25) had an electrical size that was ka ˜0.46 at 105.2 MHz (where a is the radius of the minimum enclosing hemisphere). Nearly complete matching to the 50 ? source and a high overall efficiency (nearly 95%) were achieved. The numerically predicted and the measured results were in good agreement.

Lin, Chia-Ching; Ziolkowski, Richard W.; Nielsen, Jean A.; Tanielian, Minas H.; Holloway, Christopher L.

2010-03-01

7

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

8

Electrically Small Microstrip Quarter-Wave Monopole Antennas  

NASA Technical Reports Server (NTRS)

Microstrip-patch-style antennas that generate monopole radiation patterns similar to those of quarter-wave whip antennas can be designed to have dimensions smaller than those needed heretofore for this purpose, by taking advantage of a feed configuration different from the conventional one. The large sizes necessitated by the conventional feed configuration have, until now, made such antennas impractical for frequencies below about 800 MHz: for example, at 200 MHz, the conventional feed configuration necessitates a patch diameter of about 8 ft (.2.4 m) . too large, for example, for mounting on the roof of an automobile or on a small or medium-size aircraft. By making it possible to reduce diameters to between a tenth and a third of that necessitated by the conventional feed configuration, the modified configuration makes it possible to install such antennas in places where they could not previously be installed and thereby helps to realize the potential advantages (concealment and/or reduction of aerodynamic drag) of microstrip versus whip antennas. In both the conventional approach and the innovative approach, a microstrip-patch (or microstrip-patch-style) antenna for generating a monopole radiation pattern includes an electrically conductive patch or plate separated from an electrically conductive ground plane by a layer of electrically insulating material. In the conventional approach, the electrically insulating layer is typically a printed-circuit board about 1/16 in. (.1.6 mm) thick. Ordinarily, a coaxial cable from a transmitter, receiver, or transceiver is attached at the center on the ground-plane side, the shield of the cable being electrically connected to the ground plane. In the conventional approach, the coaxial cable is mated with a connector mounted on the ground plane. The center pin of this connector connects to the center of the coaxial cable and passes through a hole in the ground plane and a small hole in the insulating layer and then connects with the patch above one-third of the radial distance from the center. The modified feed configuration of the innovative approach is an inductive-short-circuit configuration that provides impedance matching and that has been used for many years on other antennas but not on microstrip-style monopole antennas. In this configuration, the pin is connected to both the conductive patch and the ground plane. As before, the shield of the coaxial cable is connected to the ground plane, but now the central conductor is connected to a point on the pin between the ground plane and the conductive plate (see figure). The location of the connection point on the pin is chosen so that together, the inductive short circuit and the conductive plate or patch act as components of a lumped-element resonant circuit that radiates efficiently at the resonance frequency and, at the resonance frequency, has an impedance that matches that of the coaxial cable. It should be noted that the innovative design entails two significant disadvantages. One disadvantage is that the frequency bandwidth for efficient operation is only about 1/20 to 1/15 that of a whip antenna designed for the same nominal frequency. The other disadvantage is that the estimated gain is between 3-1/2 and 4-1/2 dB below that of the whip antenna. However, if an affected radio-communication system used only a few adjacent frequency channels and the design of the components of the system other than the antenna provided adequate power or gain margin, then these disadvantages could be overcome.

Young, W. Robert

2004-01-01

9

An Efficient, Electrically Small Antenna Designed for VHF and UHF Applications  

Microsoft Academic Search

An electrically small electric-based metamaterial-in- spired antenna that is designed for narrow bandwidth operations in the VHF and UHF bands is presented. It is demonstrated that the idealized lossless versions have overall efficiencies at 100% without any external matching circuits and quality factors approaching the Chu limit. When conductor losses are introduced, the overall efficiencies remain high.

Richard W. Ziolkowski

2008-01-01

10

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 54, NO. 7, JULY 2006 2113 Metamaterial-Based Efficient Electrically Small  

E-print Network

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 54, NO. 7, JULY 2006 2113 Metamaterial--A metamaterial paradigm for achieving an efficient, electrically small antenna is introduced. Spherical shells of ho- mogenous, isotropic negative permittivity (ENG) material are designed to create electrically

Ziolkowski, Richard W.

11

Development of an Electrically Small Vivaldi Antenna: The CReSIS Aerial Vivaldi (CAV-A)  

E-print Network

Radar operation from the CReSIS Meridian UAV requires a broadband antenna array composed of lightweight, thin, end-fire antenna elements. Toward this goal four Vivaldi antenna designs were simulated, fabricated, and characterized. The final design...

Panzer, Benjamin Garrett

2007-12-12

12

Conformal microstrip antennas and microstrip phased arrays  

Microsoft Academic Search

A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.

R. Munson

1974-01-01

13

Electromagnetic characterization of conformal antennas  

NASA Technical Reports Server (NTRS)

The ultimate objective of this project is to develop a new technique which permits an accurate simulation of microstrip patch antennas or arrays with various feed, superstrate and/or substrate configurations residing in a recessed cavity whose aperture is planar, cylindrical or otherwise conformed to the substructure. The technique combines the finite element and boundary integral methods to formulate a system suitable for solution via the conjugate gradient method in conjunction with the fast Fourier transform. The final code is intended to compute both scattering and radiation patterns of the structure with an affordable memory demand. With upgraded capabilities, the four included papers examined the radar cross section (RCS), input impedance, gain, and resonant frequency of several rectangular configurations using different loading and substrate/superstrate configurations.

Volakis, John L.; Kempel, Leo C.; Alexanian, Angelos; Jin, J. M.; Yu, C. L.; Woo, Alex C.

1992-01-01

14

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

15

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

E-print Network

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...

Speer, Peter Clark

2009-01-01

16

Hemispherical coil electrically small antenna made by stretchable conductors printing and plastic thermoforming  

NASA Astrophysics Data System (ADS)

A production scalable technique is presented to make hemispherical coil antennas by using a stretchable printed silver paste conductor and plastic thermoforming. To ease the fabrication process an unbalanced feed-structure was designed for solderless mounting on conductive materials. The manufactured antenna had a resonance frequency of 2.467?GHz with a reflection coefficient of ?33.8?dB. The measured and simulated radiation patterns corresponded to that of monopole structure and the measured efficiency was 40%.

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

2015-02-01

17

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

18

New Concept Conformal Antennas Utilizing Metamaterial and Transformation Optics  

E-print Network

In this letter, we show by theoretical analysis and computer simulation that conformal antennas can be designed using metamaterial with inhomogeneous constitutive parameters by applying the electromagnetic coordinate ...

Luo, Yu

19

Conformal, Transparent Printed Antenna Developed for Communication and Navigation Systems  

NASA Technical Reports Server (NTRS)

Conformal, transparent printed antennas have advantages over conventional antennas in terms of space reuse and aesthetics. Because of their compactness and thin profile, these antennas can be mounted on video displays for efficient integration in communication systems such as palmtop computers, digital telephones, and flat-panel television displays. As an array of multiple elements, the antenna subsystem may save weight by reusing space (via vertical stacking) on photovoltaic arrays or on Earth-facing sensors. Also, the antenna could go unnoticed on automobile windshields or building windows, enabling satellite uplinks and downlinks or other emerging high-frequency communications.

Lee, Richard Q.; Simons, Rainee N.

1999-01-01

20

Conformal VHF antenna for the Apollo-Soyuz test project  

Microsoft Academic Search

A dual-band VHF microstrip antenna conformal to the exterior of the Apollo Command\\/Service Module, and mechanically and thermally compatible with the launch and orbital environments of the Apollo vehicle, is designed for detection and measurement of localized gravitational anomalies as part of the Apollo mission. The article discusses the antenna design, conversion from linear to circular polarization, beamwidth minimization, and

G. G. Sanford; R. E. Munson

1975-01-01

21

Control of radar cross sections of electrically small high temperature superconducting antenna elements using a magnetic field  

NASA Astrophysics Data System (ADS)

The radar cross sections (RCS) of small circular loops made from YBCO high temperature superconductor are calculated as a function of applied magnetic field strength. It is shown that the RCS is reduced as the magnetic field increases, and that the effect is more pronounced as radiation resistance decreases. Two factors contributing to the RCS reductions are identified, firstly an increase in surface resistance with magnetic field, and secondly a detuning effect caused by a change in the loop input reactance. It is suggested that antennas might be made from superconductor as a means of controlling their RCS, rather than for improved efficiency.

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

1994-06-01

22

Conformal Antenna Array for Millimeter-Wave Communications: Performance Evaluation  

E-print Network

In this paper, we study the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array. Bent antenna array structures on cylindrical surfaces may have important applications in future mobile devices. Small radii may be needed if the antenna is printed on the edges of mobile devices and in items which human beings are wearing, such as wrist watches, bracelets and rings. The antenna under study consists of four linear series-fed arrays of four patch elements and is operating at 58.8 GHz with linear polarization. The antenna array is fabricated on polytetrafluoroethylene substrate with thickness of 0.127 mm due to its good plasticity properties and low losses. Results for both planar and conformal antenna arrays show rather good agreement between simulation and measurements. The results show that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select betw...

Semkin, V; Kyro, M; Kolmonen, V-M; Luxey, C; Ferrero, F; Devillers, F; Raisanen, A V

2015-01-01

23

Thin conformal antenna array for microwave power conversions  

NASA Technical Reports Server (NTRS)

A structure of a circularly polarized, thin conformal, antenna array which may be mounted integrally with the skin of an aircraft employs microstrip elliptical elements and interconnecting feed lines spaced from a circuit ground plane by a thin dielectric layer. The feed lines are impedance matched to the elliptical antenna elements by selecting a proper feedpoint inside the periphery of the elliptical antenna elements. Diodes connected between the feed lines and the ground plane rectify the microwave power, and microstrip filters (low pass) connected in series with the feed lines provide dc current to a microstrip bus. Low impedance matching strips are included between the elliptical elements and the rectifying and filtering elements.

Dickinson, R. M. (inventor)

1978-01-01

24

Impact damage and antenna performance of conformal load-bearing antenna structures  

Microsoft Academic Search

Experimental investigations into the impact response and damage of conformal load-bearing antenna structures composed of a face-skin, a core and a ground plate have been carried out. The damage was examined using non-destructive and destructive methods. The performance of the damaged antenna structure was investigated by measuring the return loss and the radiation pattern in a laboratory compact range. We

C K Kim; L M Lee; H C Park; W Hwang; W S Park

2003-01-01

25

Development of a Low Profile Conformal UHF RFID Tag Antenna for Identification of Water Bottles  

E-print Network

Development of a Low Profile Conformal UHF RFID Tag Antenna for Identification of Water Bottles--Development of a low profile conformal RFID tag antenna with an omnidirectional pattern when mounted on a water bottle water bottle is developed. The design challenges discussed include achieving sufficient antenna

Elsherbeni, Atef Z.

26

A finite element-boundary integral method for conformal antenna arrays on a circular cylinder  

NASA Technical Reports Server (NTRS)

Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This is due to the lack of rigorous mathematical models for conformal antenna arrays, and as a result the design of conformal arrays is primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. Herewith we shall extend this formulation for conformal arrays on large metallic cylinders. In this we develop the mathematical formulation. In particular we discuss the finite element equations, the shape elements, and the boundary integral evaluation, and it is shown how this formulation can be applied with minimal computation and memory requirements. The implementation shall be discussed in a later report.

Kempel, Leo C.; Volakis, John L.; Woo, Alex C.; Yu, C. Long

1992-01-01

27

A finite element-boundary integral method for conformal antenna arrays on a circular cylinder  

NASA Technical Reports Server (NTRS)

Conformal antenna arrays offer many cost and weight advantages over conventional antenna systems. In the past, antenna designers have had to resort to expensive measurements in order to develop a conformal array design. This was due to the lack of rigorous mathematical models for conformal antenna arrays. As a result, the design of conformal arrays was primarily based on planar antenna design concepts. Recently, we have found the finite element-boundary integral method to be very successful in modeling large planar arrays of arbitrary composition in a metallic plane. We are extending this formulation to conformal arrays on large metallic cylinders. In doing so, we will develop a mathematical formulation. In particular, we discuss the finite element equations, the shape elements, and the boundary integral evaluation. It is shown how this formulation can be applied with minimal computation and memory requirements.

Kempel, Leo C.; Volakis, John L.

1992-01-01

28

CAD package to design rectangular probe-fed microstrip antennas conformed on cylindrical structures  

Microsoft Academic Search

This paper describes a homemade CAD package developed to design and analyze rectangular probe-fed microstrip antennas conformed on cylindrical structures. This CAD (named Cylindrical) provides a friendly environment, making the design and analysis of these antennas easy. The theory used to develop the software is described first. Then, a right-handed circularly polarized antenna to operate at 2.25 GHz is designed.

Marcos V. T. Heckler; M. Bonadiman; Ricardo Schildberg; Lucio Cividanes; J. C. S. Lacava

2003-01-01

29

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 8, 2009 653 A Novel Conformal RFID-Enabled Module Utilizing  

E-print Network

with the antenna, for a low cost, flexible, highly integrated RFID module. Carbon nanotubes (CNT) composites haveIEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 8, 2009 653 A Novel Conformal RFID time the integration of a conformal radio frequency identification (RFID) antenna with a single

Tentzeris, Manos

30

Radiation and scattering from cylindrically conformal printed antennas. Ph.D. Thesis Final Report  

NASA Technical Reports Server (NTRS)

Microstrip patch antennas offer considerable advantages in terms of weight, aerodynamic drag, cost, flexibility, and observables over more conventional protruding antennas. These flat patch antennas were first proposed over thirty years ago by Deschamps in the United States and Gutton and Baisinot in France. Such antennas have been analyzed and developed for planar as well as curved platforms. However, the methods used in these designs employ gross approximations, suffer from extreme computational burden, or require expensive physical experiments. The goal of this thesis is to develop accurate and efficient numerical modeling techniques which represent actual antenna structures mounted on curved surfaces with a high degree of fidelity. In this thesis, the finite element method is extended to cavity-backed conformal antenna arrays embedded in a circular, metallic, infinite cylinder. Both the boundary integral and absorbing boundary mesh closure conditions will be used for terminating the mesh. These two approaches will be contrasted and used to study the scattering and radiation behavior of several useful antenna configurations. An important feature of this study will be to examine the effect of curvature and cavity size on the scattering and radiation properties of wraparound conformal antenna arrays.

Kempel, Leo C.; Volakis, John L.

1994-01-01

31

Characteristics of a Linearly Tapered Slot Antenna (LTSA) Conformed Longitudinally Around a Cylinder  

NASA Technical Reports Server (NTRS)

The family of tapered slot antennas (TSA s) is suitable for numerous applications. Their ease of fabrication, wide bandwidth, and high gain make them desirable for military and commercial systems. Fabrication on thin, flexible substrates allows the TSA to be conformed over a given body, such as an aircraft wing or a piece of clothing for wearable networks. Previously, a Double Exponentially Tapered Slot Antenna (DETSA) was conformed around an exponential curvature, which showed that the main beam skewed towards the direction of curvature. This paper presents a Linearly Tapered Slot Antenna (LTSA) conformed longitudinally around a cylinder. Measured and simulated radiation patterns and the direction of maximum H co-polarization (Hco) as a function of the cylinder radius are presented.

Jordan, Jennifer L.; Ponchak, George E.; Tavassolian, Negar; Tentzeris, Manos M.

2007-01-01

32

Space-time adaptive processing with a half-cylinder faceted conformal antenna  

Microsoft Academic Search

Conformal antennas, which assumes the shape of the platform, have several advantages, like reduced weight and space; aerodynamic design and increased field of view.We are interested in detection of moving ground targets with air-borne radar with three antenna geometries: faceted or smooth vertical half-cylinder and plane forward-looking. We study important clutter properties for suppressing the clutter with STAP (Space-Time Adaptive

Svante Björklund

2009-01-01

33

Designing of a small wearable conformal phased array antenna for wireless communications  

NASA Astrophysics Data System (ADS)

In this thesis, a unique design of a self-adapting conformal phased-array antenna system for wireless communications is presented. The antenna system is comprised of one microstrip antenna array and a sensor circuit. A 1x4 printed microstrip patch antenna array was designed on a flexible substrate with a resonant frequency of 2.47 GHz. However, the performance of the antenna starts to degrade as the curvature of the surface of the substrate changes. To recover the performance of the system, a flexible sensor circuitry was designed. This sensor circuitry uses analog phase shifters, a flexible resistor and operational-amplifier circuitry to compensate the phase of each array element of the antenna. The proposed analytical method for phase compensation has been first verified by designing an RF test platform consisting of a microstrip antenna array, commercially available analog phase shifters, analog voltage attenuators, 4-port power dividers and amplifiers. The platform can be operated through a LabVIEW GUI interface using a 12-bit digital-to-analog converter. This test board was used to design and calibrate the sensor circuitry by observing the behavior of the antenna array system on surfaces with different curvatures. In particular, this phased array antenna system was designed to be used on the surface of a spacesuit or any other flexible prototype. This work was supported in part by the Defense Miroelectronics Activity (DMEA), NASA ND EPSCoR and DARPA/MTO.

Roy, Sayan

34

A Novel Planar Conformal Antenna Designed With Splines  

Microsoft Academic Search

A broadband planar dipole, radiating from 280 to 1000 MHz (with Gain > 0 dBi), is considered for shape optimization using splines. It is demonstrated via simulations and measurements that the 0 dBi gain point is shifted to 190 MHz (32% size reduction). The entire optimization amounts to antenna reshaping.

Stavros Koulouridis; John L. Volakis

2009-01-01

35

Simulation of Conformal Spiral Slot Antennas on Composite Platforms  

NASA Technical Reports Server (NTRS)

During the course of the grant, we wrote and distributed about 12 reports and an equal number of journal papers supported fully or in part by this grant. The list of reports (title & abstract) and papers are given in Appendices A and B. This grant has indeed been instrumental in developing a robust hybrid finite element method for the analysis of complex broadband antennas on doubly curved platforms. Previous to the grant, our capability was limited to simple printed patch antennas on mostly planar platforms. More specifically: (1) mixed element formulations were developed and new edge-based prisms were introduced; (2) these elements were important in permitting flexibility in geometry gridding for most antennas of interest; (3) new perfectly matched absorbers were introduced for mesh truncations associated with highly curved surfaces; (4) fast integral algorithms were introduced for boundary integral truncations reducing CPU time from O(N-2) down to O(N-1.5) or less; (5) frequency extrapolation schemes were developed for efficient broadband performance evaluations. This activity has been successfully continued by NASA researchers; (6) computer codes were developed and extensively tested for several broadband configurations. These include FEMA-CYL, FEMA-PRISM and FEMA-TETRA written by L. Kempel, T. Ozdemir and J. Gong, respectively; (7) a new infinite balun feed was designed nearly constant impedance over the 800-3000 MHz operational band; (8) a complete slot spiral antenna was developed, fabricated and tested at NASA Langley. This new design is a culmination of the projects goals and integrates the computational and experimental efforts. this antenna design resulted in a U.S. patent and was revised three times to achieve the desired bandwidth and gain requirements from 800-3000 MHz.

Volakis, J. L.; Nurnberger, M. W.; Ozdemir,T.

1998-01-01

36

Iterative least-squares synthesis methods for conformal array antennas with optimized polarization and frequency properties  

Microsoft Academic Search

An iterative least-squares synthesis technique is presented for the optimization of the element excitation in conformal array antennas. This method allows the designer to have predefined goals for the shaped radiation pattern over a selected frequency band and for the polarization properties of the array. Linear or circular polarization can be used in the synthesis. Different kinds of synthesis goals

Leo I. Vaskelainen

1997-01-01

37

Radiation and scattering from printed antennas on cylindrically conformal platforms  

NASA Technical Reports Server (NTRS)

The goal was to develop suitable methods and software for the analysis of antennas on cylindrical coated and uncoated platforms. Specifically, the finite element boundary integral and finite element ABC methods were employed successfully and associated software were developed for the analysis and design of wraparound and discrete cavity-backed arrays situated on cylindrical platforms. This work led to the successful implementation of analysis software for such antennas. Developments which played a role in this respect are the efficient implementation of the 3D Green's function for a metallic cylinder, the incorporation of the fast Fourier transform in computing the matrix-vector products executed in the solver of the finite element-boundary integral system, and the development of a new absorbing boundary condition for terminating the finite element mesh on cylindrical surfaces.

Kempel, Leo C.; Volakis, John L.; Bindiganavale, Sunil

1994-01-01

38

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

39

Locally conformal FDTD modeling of MEMS-Based antenna sensors for melanoma detection  

Microsoft Academic Search

The full-wave characterization of reconfigurable antenna sensors for non-invasive detection of melanoma is presented. To this end, an enhanced locally conformal finite- difference time-domain numerical procedure, based on a suitable normalization of the electromagnetic field-related quantities, is adopted. In this way, a physical insight in wave diffraction phenomena occurring in the radar monitoring of skin cancers, as well as in

D. Caratelli; A. Yarovoy; A. Massaro; R. Cingolani; A. Lay-Ekuakille

2011-01-01

40

Study of inkjet printing as an ultra-low-cost antenna prototyping method and its application to conformal wraparound antennas for sounding rocket sub-payload  

NASA Astrophysics Data System (ADS)

Inkjet printing is an attractive patterning technology that has received tremendous interest as a mass fabrication method for a variety of electronic devices due to its manufacturing exibility and low-cost feature. However, the printing facilities that are being used, especially the inkjet printer, are very expensive. This thesis introduces an extremely cost-friendly inkjet printing method using a printer that costs less than $100. In order to verify its reliability, linearly and circularly polarized (CPd) planar and conformal microstrip antennas were fabricated using this printing method, and their measurement results were compared with copper microstrip antennas. The result shows that the printed microstrip antennas have similar performances to those of the copper antennas except for lower efficiency. The effects of the conductivity and thickness of the ink layer on the antenna properties were studied, and it is found that the conductivity is the main factor affecting the radiation efficiency, though thicker ink yields more effective antennas. This thesis also presents the detailed antenna design for a sub-payload. The sub-payload is a cylindrical structure with a diameter of six inches and a height of four inches. It has four booms coming out from the surface, which are used to measure the variations of the energy flow into the upper atmosphere in and around the aurora. The sub-payload has two types of antennas: linearly polarized (LPd) S-band antennas and right-hand circularly polarized (RHCPd) GPS antennas. Each type of antenna has various requirements to be fully functional for specific research tasks. The thesis includes the design methods of each type of antenna, challenges that were confronted, and the possible solutions that were proposed. As a practical application, the inkjet printing method was conveniently applied in validating some of the antenna designs.

Maimaiti, Maimaitirebike

41

Radiation pattern synthesis for arrays of conformal antennas mounted on arbitrarily-shaped three-dimensional platforms using genetic algorithms  

Microsoft Academic Search

A domain-decomposition\\/reciprocity procedure is presented which allows the radiation patterns of microstrip patch antennas mounted on arbitrarily-shaped three-dimensional perfectly electric conducting (PEC) platforms to be computed accurately as well as efficiently. The utility of this technique is demonstrated by considering an example consisting of a nine-element conformal array of microstrip patch antennas mounted axially along a finite-length PEC circular cylinder.

Rene J. Allard; Douglas H. Werner; Pingjuan L. Werner

2003-01-01

42

Shaping and resizing of multifed slot radiators used in conformal microwave antenna arrays for hyperthermia treatment of large superficial diseases.  

PubMed

It has been recently shown that chestwall recurrence of breast cancer and many other superficial diseases can be successfully treated with the combination of radiation, chemotherapy and hyperthermia. Conformal microwave antenna array for hyperthermia treatment of large area superficial diseases can significantly increase patient comfort while at the same time facilitate treatment of larger and more irregularly shaped disease. A large number of small efficient antennas is preferable for improved control of heating, as the disease can be more accurately contoured and the lower power requirement correlates with system reliability, linearity and reduced cost. Thus, starting from the initially proposed square slot antennas, we investigated new designs for multi-fed slot antennas of several shapes that maximize slot perimeter while reducing radiating area, thus increasing antenna efficiency. Simulations were performed with commercial electromagnetic simulation software packages (Ansoft HFSS) to demonstrate that the antenna size reduction method is effective for several dual concentric conductor (DCC) aperture shapes and operating frequencies. The theoretical simulations allowed the development of a set of design rules for multi-fed DCC slot antennas that facilitate conformal heat treatments of irregular size and shape disease with large multi-element arrays. Independently on the shape, it is shown that the perimeter of 10cm at 915 MHz delivers optimal radiation pattern and efficiency. While the maximum radiation is obtained for a circular pattern the rectangular shape is the one that feels more efficiently the array space. PMID:24352575

Maccarini, Paolo F; Arunachalam, Kavitha; Juang, Titania; De Luca, Valeria; Rangarao, Sneha; Neumann, Daniel; Martins, Carlos Daniel; Craciunescu, Oana; Stauffer, Paul R

2009-01-01

43

Considerations on terminal antenna design and analysis  

Microsoft Academic Search

The explosion of modern wireless services has drastically increased the need for efficient electrically small antennas for the handheld terminals. However and opposite to electronic devices, efficiency in antennas is limited by fundamental physical principles. In this paper we present a short summary on the theoretical limitation of the performances of electrically small antennas, and then present some design strategies.

Anja K. Skrivervik; Juan R. Mosig

2008-01-01

44

Conformal double exponentially tapered slot antenna (DETSA) on LCP for UWB applications  

Microsoft Academic Search

We discuss the use of a double exponentially tapered slot antenna (DETSA) fabricated on flexible liquid crystal polymer (LCP) as a candidate for ultrawideband (UWB) communications systems. The features of the antenna and the effect of the antenna on a transmitted pulse are investigated. Return loss and E and H plane radiation pattern measurements are presented in several frequencies covering

Symeon Nikolaou; George E. Ponchak; John Papapolymerou; Manos M. Tentzeris

2006-01-01

45

Manufacture of a conformal multilayer rf antenna substrate using excimer mask imaging technology and a 6-axis robot  

NASA Astrophysics Data System (ADS)

A novel method is presented to produce a high precision pattern of copper tracks on both sides of a 4-layer conformal radar antenna made of PEI polymer and shaped as a truncated pseudo-parabolic cylinder. The antenna is an active emitter-receiver so that an accuracy of a fraction of the wavelength of the microwave radiation is required. After 2D layer design in Allegro, the resulting Gerber file-format circuits are wrapped around the antenna shape, resulting in a cutter-path file which provides the input for a postprocessor that outputs G-code for robot- and laser control. A rules file contains embedded information such as laser parameters and mask aperture related to the Allegro symbols. The robot consists of 6 axes that manipulate the antenna, and 2 axes for the mask plate. The antenna can be manipulated to an accuracy of +/- 20 micrometers over its full dimensions of 200x300x50 mm. The four layers are constructed by successive copper coating, resist coating, laser ablation, copper etching, resist removal, insulation polyimide film lamination and laser dielectric drilling for microvia holes and through-holes drilling. Applications are in space and aeronautical communication and radar detection systems, with possible extensions to automotive and mobile hand-sets, and land stations.

Charrier, Michel; Everett, Daniel; Fieret, Jim; Karrer, Tobias; Rau, Sven; Valard, Jean-Luc

2001-06-01

46

Antenna Technologies for NASA Applications  

NASA Technical Reports Server (NTRS)

This presentation addresses the efforts being performed at GRC to develop antenna technology in support of NASA s Exploration Vision. In particular, the presentation discusses the communications architecture asset-specific data services, as well as wide area coverage, high gain, low mass deployable antennas. Phased array antennas as well as electrically small, lightweight, low power, multifunctional antennas will be also discussed.

Miranda, Felix

2007-01-01

47

Antenna Technologies for NASA Applications  

NASA Technical Reports Server (NTRS)

This presentation addresses the efforts being performed at GRC to develop antenna technology in support of NASA s Exploration Vision. In particular, the presentation discusses the communications architecture asset-specific data services, as well as wide area coverage, high gain, low mass deployable antennas. Phased array antennas as well as electrically small, lightweight, low power, multifunctional antennas will be also discussed.

Miranda, Felix A.

2006-01-01

48

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

PubMed

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. PMID:24224073

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

2009-02-23

49

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

PubMed Central

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. PMID:24224073

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

2013-01-01

50

Design optimization of conformal antennas by integrating stochastic algorithms with the hybrid finite-element method  

Microsoft Academic Search

Previous work in antenna optimization has primarily focused on applications of optimization algorithms in conjunction with problem-specific or semi-analytic tools. However, previous developments in fast algorithms now offer the possibility of designs and moreover allow for full flexibility in material specification across three dimensions. As an example, this paper combines genetic algorithms (GA) and simulated annealing (SA) with fast hybrid

Zhifang Li; Yunus E. Erdemli; John L. Volakis; Panos Y. Papalambros

2002-01-01

51

Focusing and impedance properties of conformable phased array antennas for microwave hyperthermia  

SciTech Connect

Phased array applicators for microwave hyperthermia are usually developed using planar, layered tissue models, and then evaluated using numerical techniques. The present investigation considers the use of a cylindrical, layered tissue model to replace the first step of the design procedure. This model facilitates an evaluation of the impact of curvature, polarization, and bolus materials on the antenna performance.

Najafabadi, R.M.; Peterson, A.F. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical and Computer Engineering] [Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical and Computer Engineering

1996-10-01

52

Impact Behavior and Radiation Performance of a Structurally Integrated Antenna Array Conformed Around Cylindrical Bodies  

E-print Network

of aramid paper and phenolic resin gives the superior strength, toughness and chemical resistance consisting of glass/epoxy facesheet and honeycomb core is used as a basic mechanical topology, in which on the antenna characteristics, but its thickness must provide the necessary structural rigidity. Glass

Tentzeris, Manos

53

Body conformal antennas for superficial hyperthermia: the impact of bending contact flexible microstrip applicators on their electromagnetic behavior.  

PubMed

Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field distributions in a cylindrical patient model. Due to their large size multimode solutions may exist, and our results confirm their existence. These multimode solutions affect both the power distribution and PD/EHD, with a dependence on applicator curvature. Therefore, the performance parameters like PD and EHD need to be carefully assessed when bending large size CFMA applicators to conform to the patient body. This conclusion also holds for other types of large size surface current applicators. PMID:19695983

Correia, Davi; Kok, H Petra; de Greef, Martijn; Bel, Arjan; van Wieringen, Niek; Crezee, Johannes

2009-12-01

54

constructed and measured. These very small antennas ( /5 per /9 at low frequency limit) present good radiation performances over  

E-print Network

by an electrically-small semi-circular loop antenna, which is coaxially-fed through a finite ground plane.interscience.wiley.com). DOI 10.1002/mop. 22415 Key words: metamaterials; electrically small antennas; loop antennas; antennaconstructed and measured. These very small antennas ( /5 per /9 at low frequency limit) present

Ziolkowski, Richard W.

55

PCS antenna design: the challenge of miniaturization  

Microsoft Academic Search

PCS (personal communication system) devices have become an important part of everyday life. The pressure to design small, lightweight, and user-friendly mobile-communication devices has increased accordingly, creating the need for optimal antennas for mobile applications. In this paper, we present some basic rules about electrically small antennas, give clues and guidelines about efficient antenna miniaturization, and, finally, show some examples

A. K. Skrivervik; J.-F. Zurcher; O. Staub; J. R. Mosig

2001-01-01

56

Analysis of cylindrical wrap-around and doubly conformal patch antennas by way of the finite element-artificial absorber method  

NASA Technical Reports Server (NTRS)

The goal of this project was to develop analysis codes for computing the scattering and radiation of antennas on cylindrically and doubly conformal platforms. The finite element-boundary integral (FE-BI) method has been shown to accurately model the scattering and radiation of cavity-backed patch antennas. Unfortunately extension of this rigorous technique to coated or doubly curved platforms is cumbersome and inefficient. An alternative approximate approach is to employ an absorbing boundary condition (ABC) for terminating the finite element mesh thus avoiding use of a Green's function. A FE-ABC method is used to calculate the radar cross section (RCS) and radiation pattern of a cavity-backed patch antenna which is recessed within a metallic surface. It is shown that this approach is accurate for RCS and antenna pattern calculations with an ABC surface displaced as little as 0.3 lambda from the cavity aperture. These patch antennas may have a dielectric overlay which may also be modeled with this technique.

Volakis, J. L.; Kempel, L. C.; Sliva, R.; Wang, H. T. G.; Woo, A. G.

1994-01-01

57

Planar Microstrip Yagi Antennas  

NASA Technical Reports Server (NTRS)

Developmental class of antennas based on combination of microstrip-patch and Yagi-array concepts. Mutual coupling between microstrip elements, ordinarily considered nuisance, used to advantage. Applicable to both linearly and circularly polarized antennas. Use of fewer driven elements results in less complexity and reduced loss of power in associated transmission lines and other coupling and power-distributing circuitry. Applications include antennas on land vehicles, television receiving antennas, and conformal antennas on aircraft.

Huang, John

1990-01-01

58

Modeling the NMR signatures associated with the functional conformational switch in the major light-harvesting antenna of photosystem II in higher plants.  

PubMed

The major photosystem II antenna complex, LHCII, possesses an intrinsic conformational switch linked to the formation of a photoprotective, excitation-quenching state. Recent solid state NMR experiments revealed that aggregation-induced quenching in (13)C-enriched LHCII from C. reinhardtii is associated with changes to the chemical shifts of three specific (13)C atoms in the Chla conjugated macrocycle. We performed DFT-based NMR calculations on the strongly-quenched crystal structure of LHCII (taken from spinach). We demonstrate that specific Chla-xanthophyll interactions in the quenched structure lead to changes in the Chla(13)C chemical shifts that are qualitatively similar to those observed by solid state NMR. We propose that these NMR changes are due to modulations in Chla-xanthophyll associations that occur due to a quenching-associated functional conformation change in the lutein and neoxanthin domains of LHCII. The combination of solid-state NMR and theoretical modeling is therefore a powerful tool for assessing functional conformational switching in the photosystem II antenna. PMID:24513782

Duffy, Christopher D P; Pandit, Anjali; Ruban, Alexander V

2014-03-28

59

Effect of asymmetric feeding and meander in the dual-band antenna design  

Microsoft Academic Search

This paper detail the effects of asymmetric feeding and meander in the dual-band antenna design. TVBhe antenna used is electrically small rectangular patch with short circuit. The changed in the feeding position (asymmetric feeding) combined with introduction of meander in the patch to obtain miniaturized antenna with news resonates modes. These antennas could be suitably used in some applications that

C. M. Costa Jr; G. Fontgalland; T. P. Vuong; S. E. Barbin; R. P. P. Rodrigues Jr; R. C. S. Freire; R. N. Lima

2010-01-01

60

Square-Spiral Microstrip Antennas  

NASA Technical Reports Server (NTRS)

Square-spiral microstrip antennas for wideband reception at frequencies of several gigahertz proposed. These could be made to conform to surfaces of aircraft and other vehicles. Offers advantage of thinness. Square shapes of spirals in these spiral microstrip antennas offers advantage over curved shapes of spirals of other spiral microstrip antennas in that square shapes simplifies fabrication.

Shively, David G.

1994-01-01

61

Design Goals Electrically small a few meters in size  

E-print Network

;CENTER FOR PULSED POWER AND POWER ELECTRONICS HAARP Facility · High Frequency Active Auroral Research · 180 antenna structures in a 12�15 array on ~33 acres 3/13/2014 2 HAARP Facility #12;CENTER FOR PULSED

Anlage, Steven

62

Printed Monopole Antennas with Increased Bandwidth and Gain for Wi-Fi Applications  

E-print Network

Printed Monopole Antennas with Increased Bandwidth and Gain for Wi-Fi Applications Nevin Altunyurt, compact antennas that can integrate well into future portable wireless communication devices. Owing, electrically small planar antennas are seen as the favorable candidates to be used in such systems

Swaminathan, Madhavan

63

X-Antenna: A graphical interface for antenna analysis codes  

NASA Technical Reports Server (NTRS)

This report serves as the user's manual for the X-Antenna code. X-Antenna is intended to simplify the analysis of antennas by giving the user graphical interfaces in which to enter all relevant antenna and analysis code data. Essentially, X-Antenna creates a Motif interface to the user's antenna analysis codes. A command-file allows new antennas and codes to be added to the application. The menu system and graphical interface screens are created dynamically to conform to the data in the command-file. Antenna data can be saved and retrieved from disk. X-Antenna checks all antenna and code values to ensure they are of the correct type, writes an output file, and runs the appropriate antenna analysis code. Volumetric pattern data may be viewed in 3D space with an external viewer run directly from the application. Currently, X-Antenna includes analysis codes for thin wire antennas (dipoles, loops, and helices), rectangular microstrip antennas, and thin slot antennas.

Goldstein, B. L.; Newman, E. H.; Shamansky, H. T.

1995-01-01

64

Experimental demonstration of superdirective dielectric antenna  

SciTech Connect

We propose and demonstrate experimentally a simple approach for achieving superdirectivity of emitted radiation for electrically small antennas based on a spherical dielectric resonator with a notch excited by a dipole source. Superdirectivity is achieved without using complex antenna arrays and for a wide range of frequencies. We also demonstrate the steering effect for a subwavelength displacement of the source. Finally, unlike previously known superdirective antennas, our design has significantly smaller losses, at the operation frequency radiation efficiency attains 80%, and matching holds in the 3%-wide frequency band without any special matching technique.

Krasnok, Alexander E.; Filonov, Dmitry S.; Belov, Pavel A. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Simovski, Constantin R. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Aalto University, School of Electric and Electronic Engineering, Aalto FI76000 (Finland); Kivshar, Yuri S. [National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101 (Russian Federation); Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2014-03-31

65

Ultra-broadband car antennas for communications and navigation applications  

Microsoft Academic Search

This paper presents two different ultra-broadband antenna designs for mobile communications and navigation, which can be integrated conformally into the bodywork of a car. Both antennas are based on the frequency-independent spiral structure. One antenna, which is intended to be integrated into the car's window, is an externally fed spiral antenna in order to obtain a flat structure. The second

Eberhard Gschwendtner; Werner Wiesbeck

2003-01-01

66

Furlable antenna. [antenna design  

NASA Technical Reports Server (NTRS)

An improved furlable antenna particularly suited for use in a celestial space environment is described. The antenna is characterized by an actuator comprising an elastomeric member of an annular configuration, an annular array of uniformly spaced antenna ribs rigidly affixed at the base ends to an actuator which enables it to be supported for pivotal displacement from a deployed configuration. The ribs are radially extended from the actuator to a furled configuration. The ribs are extended parallel to the axis of the actuator with flexible reflecting web affixed to the ribs, with angularly spaced bearing blocks.

Barnett, M. A. (inventor)

1976-01-01

67

Antenna Systems Advanced Antenna Systems  

E-print Network

EEL4461 EEL5462 Fall 2014 Antenna Systems Advanced Antenna Systems Instructor Dr. Jenshan Lin://lss.at.ufl.edu/) Textbooks Required: Balanis, Antenna Theory - Analysis and Design, 3rd ed. 2005 Prerequisite EEL3472 principles of antenna and to apply them to the design and analysis of antenna systems. Students will learn

Fang, Yuguang "Michael"

68

Spiral Microstrip Antenna with Resistance  

NASA Technical Reports Server (NTRS)

A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

Shively, David G. (Inventor)

1998-01-01

69

Design and performance of a microstrip reflectarray antenna  

E-print Network

Microstrip reflectarray antennas present an alternative to conventional directive antennas in that they are flat, easy to install and manufacture, are conformal to the mounting surface and posses high power capabilities. For the first time...

Javor, Ronald David

1994-01-01

70

Spiral microstrip antenna with resistance  

NASA Astrophysics Data System (ADS)

The present invention relates to microstrip antennas, and more particularly to wide bandwidth spiral antennas with resistive loading. A spiral microstrip antenna having resistor element embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

Shively, David G.

1994-06-01

71

Microstrip antennas  

Microsoft Academic Search

Microstrip antennas have been one of the most innovative topics in antenna theory and design in recent years, and are increasingly finding application in a wide range of modern microwave systems. This paper begins with a brief overview of the basic characteristics of microstrip antennas, and then concentrates on the most significant developments in microstrip antenna technology that have been

DAVID M. POZAR

1992-01-01

72

Planar antennas  

Microsoft Academic Search

This article reviews the state of the art in broadband antennas for emerging UWB applications and addresses the important issues of the broadband antenna design for UWB applications. First, a variety of planar monopoles with finite ground planes are reviewed. Next, the roll antennas with enhanced radiation performance are outlined. After that, the planar antennas printed on PCBs are described.

Zhi Ning Cheng; Max J. Ammann; Xianming Qing; Xuan Hui Wu; Terence S. P. See; A. Cat

2006-01-01

73

Exact Simulation Method VSWIE+MLFMA for Analysis Radiation Pattern of Probe-Feed Conformal Microstrip Antennas and the Application of Synthesis Radiation Pattern of Conformal Array Mounted on Finite-Length PEC Circular Cylinder With DEs  

Microsoft Academic Search

A method based on volume-surface-wire integral equation (VSWIE) and the multi-level fast multi-pole algorithm(MLFMA) procedure is introduced which allows the radiation patterns of microstrip patch antennas mounted on finite-length PEC circular cylinder to be computed accurately as well as efficiently. In this approach, the entire structure comprising the patch, ground plane, dielectric substrate and probe feed is included in the

J. Ouyang; F. Yang; S. W. Yang; Z. P. Nie

2007-01-01

74

Fabry-Perot Resonator Antenna  

Microsoft Academic Search

Fabry-Perot Resonator (FPR) antennas have attracted significant attention in microwave and millimeter waves due to a number\\u000a of attractive properties, such as low complexity, high directivity and conformal deployment capability. In this paper, a summary\\u000a of recent publications on FPR antenna is presented focusing on the different capabilities, technologies and architectures\\u000a that have been proposed. Several structures, analytic models and

Zhen-Guo Liu

2010-01-01

75

Deployable antenna  

NASA Technical Reports Server (NTRS)

A deployable antenna and method for using wherein the deployable antenna comprises a collapsible membrane having at least one radiating element for transmitting electromagnetic waves, receiving electromagnetic waves, or both.

Fink, Patrick W. (Inventor); Dobbins, Justin A. (Inventor); Lin, Greg Y. (Inventor); Chu, Andrew W. (Inventor); Scully, Robert C. (Inventor)

2006-01-01

76

User Antennas  

NASA Technical Reports Server (NTRS)

The following subject areas are covered: (1) impact of frequency change of user and spacecraft antenna gain and size; (2) basic personal terminal antennas (impact of 20/30 GHz frequency separation; parametric studies - gain, size, weight; gain and figure of merit (G/T); design data for selected antenna concepts; critical technologies and development goals; and recommendations); and (3) user antenna radiation safety concerns.

Jamnejad, Vahraz; Cramer, Paul

1990-01-01

77

Reconfigurable antenna pattern verification  

NASA Technical Reports Server (NTRS)

A method of verifying programmable antenna configurations is disclosed. The method comprises selecting a desired antenna configuration from a plurality of antenna configuration patterns, with the selected antenna configuration forming at least one reconfigurable antenna from reconfigurable antenna array elements. The method validates the formation of the selected antenna configuration to determine antenna performance of the at least one reconfigurable antenna.

Drexler, Jerome P. (Inventor); Becker, Robert C. (Inventor); Meyers, David W. (Inventor); Muldoon, Kelly P. (Inventor)

2013-01-01

78

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

79

Land vehicle antennas for satellite mobile communications  

NASA Technical Reports Server (NTRS)

The RF performance, size, pointing system, and cost were investigated concepts are: for a mechanically steered 1 x 4 tilted microstrip array, a mechanically steered fixed-beam conformal array, and an electronically steered conformal phased array. Emphasis is on the RF performance of the tilted 1 x 4 antenna array and methods for pointing the various antennas studied to a geosynchronous satellite. An updated version of satellite isolations in a two-satellite system is presented. Cost estimates for the antennas in quantities of 10,000 and 100,000 unites are summarized.

Haddad, H. A.; Pieper, B. V.; Mckenna, D. B.

1985-01-01

80

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

81

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

82

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 46, NO. 2, FEBRUARY 1998 275 Micromachined Patch Antennas  

E-print Network

, conformability, low manufacturing cost [1], and enormous availability of design and analysis software. As system to develop design solutions that can be integrated into monolithic circuit layouts while enhancing antenna performance. Microstrip antenna designs show significant performance degradation due to the pronounced

Papapolymerou, Ioannis "John"

83

Analysis, Design, and Operation of a Spherical Inverted-F Antenna  

E-print Network

This thesis presents the analysis, design, and fabrication of a spherical inverted-F antenna (SIFA). The SIFA consists of a spherically conformal rectangular patch antenna recessed into a quarter section of a metallic sphere. The sphere acts as a...

McDonald, Jacob J.

2010-07-14

84

Conformal phased array with beam forming for airborne satellite communication  

Microsoft Academic Search

For enhanced communication on board of aircraft novel antenna systems with broadband satellite-based capabilities are required. The installation of such systems on board of aircraft requires the development of a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In

H. Schippers; J. Verpoorte; P. Jorna; A. Hulzinga; A. Meijerink; C. G. H. Roeloffzen; R. G. Heideman; A. Leinse; M. Wintels

2008-01-01

85

Performance Analysis of Dipole Antennas Embedded in Core-Shell Spheres: A Green's Function Analysis  

E-print Network

The main goal of this work is to theoretically investigate the behavior of an electrically small antenna enclosed in a concentric sphere. The Greens function analysis is applied to characterize the input impedance of a concentric resonator excited by a dipole located at its center. The method of moments (MoM) with Galrekin's procedure is used to determine the current distribution over the source excitation and hence the input impedance. The behavior of quality factor (Q) and bandwidths of the antenna is studied with the use of input impedance as a function of frequency. We illustrate that by embedding a dipole antenna inside a core-shell structure, with magnetic shell and dielectric core, a Q as low as the Chu limit can be approached. The obtained observations demonstrate how a resonator composed of magnetic shells can provide electrically small antennas with high bandwidths performance.

Shabnam Ghadarghadr; Hossein Mosallaei

2010-05-02

86

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

87

Notch Antennas  

NASA Technical Reports Server (NTRS)

Notch antennas, also known as the tapered slot antenna (TSA), have been the topics of research for decades. TSA has demonstrated multi-octave bandwidth, moderate gain (7 to 10 dB), and symmetric E- and H- plane beam patterns and can be used for many different applications. This chapter summarizes the research activities on notch antennas over the past decade with emphasis on their most recent advances and applications. This chapter begins with some discussions on the designs of single TSA; then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the chapter, some recent developments in TSA arrays and their applications are highlighted.

Lee, Richard Q.

2004-01-01

88

Transmission of an inhomogeneous plane wave through an electrically small aperture in a perfectly conducting plane screen.  

PubMed

Most solutions for electromagnetic diffraction by a circular aperture in a perfectly conducting plane screen are for an incident homogeneous (propagating) plane wave. When the aperture is electrically small (dimensions small compared to the wavelength), the well-known transmission coefficient behaves as the fourth power of the diameter/wavelength. We consider the case in which the incident field is an inhomogeneous (evanescent) plane wave. Numerical calculations for the electrically small circular aperture show that the transmission coefficient for an inhomogeneous plane wave can be substantially greater than for a homogeneous plane wave at the same frequency. This observation may be helpful in explaining the increased transmission recently reported for electrically small apertures in plane screens with modifications. The numerical calculations for the electrically small aperture are in agreement with results from approximate analytical expressions that are based on the equivalent electric and magnetic dipole moments for the electrically small complementary disk. PMID:15191177

Petersson, L E Rickard; Smith, Glenn S

2004-06-01

89

Methodology for Efficiency Measurements of Electrically Small Monopoles for Animal Tracking  

Microsoft Academic Search

For tracking purposes, small migratory birds are outfitted with antennas and transmitters so that their daily movements and migration patterns can be observed. In order to improve the practice of tracking wildlife and to extend the ranges over which animals can be tracked, it is necessary to characterize and fully exploit the parameters of the antennas being attached to animals.

J. M. Martin; G. W. Swenson; J. T. Bernhard

2009-01-01

90

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

91

Spacecraft antennas  

NASA Astrophysics Data System (ADS)

A tutorial description is given for spacecraft antennas used for deep-space-to-Earth communication. Radiation pattern parameters, pointing errors, pointing and polarization loss, and noise characteristics are discussed.

Rahmat-Samii, Y.; Noreen, G. K.

1982-07-01

92

Narrowband and Wideband Metamaterial Antennas Based on Degenerate Band Edge and Magnetic Photonic Crystals  

Microsoft Academic Search

Electric small antennas based on anisotropic metamaterial structures are described in this paper as are wideband arrays based on metamateral ideas and the concept of the Bcurrent sheet.( ABSTRACT| Historically,antennasandmicrowavedevicesrelied on isotropic media. This provided for limited degrees of freedom (one for dielectric and another for magnetic) in the design process. In contrast, anisotropic media introduce several more degrees of

John L. Volakis; Kubilay Sertel

2011-01-01

93

Antenna Technologies for Future NASA Exploration Missions  

NASA Technical Reports Server (NTRS)

NASA s plans for the manned exploration of the moon and Mars will rely heavily on the development of a reliable communications infrastructure on the surface and back to Earth. Future missions will thus focus not only on gathering scientific data, but also on the formation of the communications network. In either case, unique requirements become imposed on the antenna technologies necessary to accomplish these tasks. For example, surface activity applications such as robotic rovers, human extravehicular activities (EVA), and probes will require small size, lightweight, low power, multi-functionality, and robustness for the antenna elements being considered. Trunk-line communications to a centralized habitat on the surface and back to Earth (e.g., surface relays, satellites, landers) will necessitate wide-area coverage, high gain, low mass, deployable antennas. Likewise, the plethora of low to high data rate services desired to guarantee the safety and quality of mission data for robotic and human exploration will place additional demands on the technology. Over the past year, NASA Glenn Research Center has been heavily involved in the development of candidate antenna technologies with the potential for meeting these strict requirements. This technology ranges from electrically small antennas to phased array and large inflatable structures. A summary of this overall effort is provided, with particular attention being paid to small antenna designs and applications. A discussion of the Agency-wide activities of the Exploration Systems Mission Directorate (ESMD) in forthcoming NASA missions, as they pertain to the communications architecture for the lunar and Martian networks is performed, with an emphasis on the desirable qualities of potential antenna element designs for envisioned communications assets. Identified frequency allocations for the lunar and Martian surfaces, as well as asset-specific data services will be described to develop a foundation for viable antenna technologies which might address these requirements and help guide future technology development decisions.

Miranda, Felix A.

2006-01-01

94

Monolithic Paper-Based & Inkjet-Printed Technology for Conformal Stepped-FMCW GPR Applications  

E-print Network

Monolithic Paper-Based & Inkjet-Printed Technology for Conformal Stepped-FMCW GPR Applications-to-add-and-subtract antennas. (a) (b) Fig. 1. System level schematic illustration of portable radar concept The GPR antenna

Tentzeris, Manos

95

Spacecraft Antennas  

NASA Technical Reports Server (NTRS)

Some of the various categories of issues that must be considered in the selection and design of spacecraft antennas for a Personal Access Satellite System (PASS) are addressed, and parametric studies for some of the antenna concepts to help the system designer in making the most appropriate antenna choice with regards to weight, size, and complexity, etc. are provided. The question of appropriate polarization for the spacecraft as well as for the User Terminal Antenna required particular attention and was studied in some depth. Circular polarization seems to be the favored outcome of this study. Another problem that has generally been a complicating factor in designing the multiple beam reflector antennas, is the type of feeds (single vs. multiple element and overlapping vs. non-overlapping clusters) needed for generating the beams. This choice is dependent on certain system design factors, such as the required frequency reuse, acceptable interbeam isolation, antenna efficiency, number of beams scanned, and beam-forming network (BFN) complexity. This issue is partially addressed, but is not completely resolved. Indications are that it may be possible to use relatively simple non-overlapping clusters of only a few elements, unless a large frequency reuse and very stringent isolation levels are required.

Jamnejad, Vahraz; Manshadi, Farzin; Rahmat-Samii, Yahya; Cramer, Paul

1990-01-01

96

Antenna theory and design  

NASA Astrophysics Data System (ADS)

Antenna fundamentals and definitions are examined, taking into account electromagnetic fundamentals, the solution of Maxwell's equations for radiation problems, the ideal dipole, the radiation pattern, directivity and gain, reciprocity and antenna pattern measurements, antenna impedance and radiation efficiency, antenna polarization, antennas in communication links and radar, and the receiving properties of antennas. Some simple radiating systems are considered along with arrays, line sources, wire antennas, broadband antennas, moment methods, and aperture antennas. High-frequency methods and aspects of antenna synthesis are discussed, giving attention to geometrical optics, physical optics, wedge diffraction theory, the ray-fixed coordinate system, the cylindrical parabolic antenna, and linear array methods.

Stutzman, W. L.; Thiele, G. A.

97

Structurally Integrated Antenna Concepts for HALE UAVs  

NASA Technical Reports Server (NTRS)

This technical memorandum describes work done in support of the Multifunctional Structures and Materials Team under the Vehicle Systems Program's ITAS (Integrated Tailored Aero Structures) Project during FY 2005. The Electromagnetics and Sensors Branch (ESB) developed three ultra lightweight antenna concepts compatible with HALE UAVs (High Altitude Long Endurance Unmanned Aerial Vehicles). ESB also developed antenna elements that minimize the interaction between elements and the vehicle to minimize the impact of wing flexure on the EM (electromagnetic) performance of the integrated array. In addition, computer models were developed to perform phase correction for antenna arrays whose elements are moving relative to each other due to wing deformations expected in HALE vehicle concepts. Development of lightweight, conformal or structurally integrated antenna elements and compensating for the impact of a lightweight, flexible structure on a large antenna array are important steps in the realization of HALE UAVs for microwave applications such as passive remote sensing and communications.

Cravey, Robin L.; Vedeler, Erik; Goins, Larry; Young, W. Robert; Lawrence, Roland W.

2006-01-01

98

Design considerations for an archimedean slot spiral antenna  

Microsoft Academic Search

The design goal is to develop a 118-157 MHz, vertically polarized, low-profile (or conformal) antenna as a replacement for VHF AM blade antennas on aircraft. This design is to be arrived at by scaling the dimensions of an antenna designed for a center frequency of 1.1 GHz. The design prior to scaling may have the following maximum dimensions: diameter less

Michael W. Nurnberger; John L. Volakis

1995-01-01

99

Design and performance of a microstrip reflectarray antenna  

Microsoft Academic Search

Microstrip reflectarray antennas present an alternative to conventional directive antennas in that they are flat, inexpensive, easy to install and manufacture, conformal to the mounting surface, easy to package, and they possess high power and beam steering capabilities. For the first time, a comprehensive, experimentally verified design procedure for the microstrip reflectarray is presented. In this design procedure, the microstrip

Ronald D. Javor; Xiao-Dong Wu; Kai Chang

1995-01-01

100

Small antennas  

Microsoft Academic Search

A small antenna is one whose size is a small fraction of the wavelength. It is a capacitor or inductor, and it is tuned to resonance by a reactor of opposite kind. Its bandwidth of impedance matching is subject to a fundamental limitation measured by its \\

H. Wheeler

1975-01-01

101

Microstrip antennas  

NASA Technical Reports Server (NTRS)

It is possible to design and construct simple, efficient microwave antenna, either linearly or circularly polarized, which should be useful in phased arrays. Mounted on thin dielectric substrate, it extends slightly above ground plane. Space behind ground plane is required for feed line and mounting hardware.

Howell, J. Q.

1973-01-01

102

Design and Development of Novel Micromachined Patch Antennas for Wireless Applications  

E-print Network

Design and Development of Novel Micromachined Patch Antennas for Wireless Applications Eve Y. Tsai on the antennas' performance is also extensively discussed and preliminary design rules are derived. 1 or conformal, can be fed in numerous configurations and also are compact and suitable for antenna array designs

Tentzeris, Manos

103

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

104

Impedance analysis of extremely low-profile antennas using metamaterial substrates  

Microsoft Academic Search

Low-profile antennas are desirable in personal communications due to attractive features such as low cost, light weight, conformability, and ease of integration. A major challenge in low-profile antenna design is the trade off between the (reduced) antenna profile and performance. This trade-off can be ameliorated by loading the antennas with properly designed metamaterials. In this paper, we explore the use

Hayrettin Odabasi; Fernando L. Teixeira

2010-01-01

105

A Review of Antenna Technologies for Future NASA Exploration Missions  

NASA Technical Reports Server (NTRS)

NASA's plans for the manned exploration of the Moon and Mars will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit and back to Earth. Future missions will thus focus not only on gathering scientific data, but also on the formation of the communications network. In either case, unique requirements become imposed on the antenna technologies necessary to accomplish these tasks. For example, proximity (i.e., short distance) surface activity applications such as robotic rovers, human extravehicular activities (EVA), and probes will require small size, lightweight, low power, multi-functionality, and robustness for the antenna elements being considered. In contrast, trunk-line communications to a centralized habitat on the surface and back to Earth (e.g., relays, satellites, and landers) will necessitate high gain, low mass antennas such as novel inflatable/deployable antennas. Likewise, the plethora of low to high data rate services desired to guarantee the safety and quality of mission data for robotic and human exploration will place additional demands on the technology. Over the last few years, NASA Glenn Research Center has been heavily involved in the development and evaluation of candidate antenna technologies with the potential for meeting the aforementioned requirements. These technologies range from electrically small antennas to phased arrays and large inflatable antenna structures. A summary of these efforts will be discussed in this paper. NASA planned activities under the Exploration Vision as they pertain to the communications architecture for the Lunar and Martian scenarios will be discussed, with emphasis on the desirable qualities of potential antenna element designs for envisioned communications assets. Identified frequency allocations for the Lunar and Martian surfaces, as well as asset-specific data services will be described to develop a foundation for viable antenna technologies which might address these requirements and help guide future technology development decisions.

Miranda, Felix A.; Nessel, James A.; Romanofsky, Robert R.; Acosta, J.

2007-01-01

106

A Review of Antenna Technologies for Future NASA Exploration Missions  

NASA Technical Reports Server (NTRS)

NASA s plans for the manned exploration of the Moon and Mars will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit and back to Earth. Future missions will thus focus not only on gathering scientific data, but also on the formation of the communications network. In either case, unique requirements become imposed on the antenna technologies necessary to accomplish these tasks. For example, proximity (i.e., short distance) surface activity applications such as robotic rovers, human extravehicular activities (EVA), and probes will require small size, lightweight, low power, multi-functionality, and robustness for the antenna elements being considered. In contrast, trunk-line communications to a centralized habitat on the surface and back to Earth (e.g., relays, satellites, and landers) will necessitate high gain, low mass antennas such as novel inflatable/deployable antennas. Likewise, the plethora of low to high data rate services desired to guarantee the safety and quality of mission data for robotic and human exploration will place additional demands on the technology. Over the last few years, NASA Glenn Research Center has been heavily involved in the development and evaluation of candidate antenna technologies with the potential for meeting the aforementioned requirements. These technologies range from electrically small antennas to phased arrays and large inflatable antenna structures. A summary of these efforts will be discussed in this paper. NASA planned activities under the Exploration Vision as they pertain to the communications architecture for the Lunar and Martian scenarios will be discussed, with emphasis on the desirable qualities of potential antenna element designs for envisioned communications assets. Identified frequency allocations for the Lunar and Martian surfaces, as well as asset-specific data services will be described to develop a foundation for viable antenna technologies which might address these requirements and help guide future technology development decisions

Miranda, Felix A.; Nessel, James A.; Romanofsky, Robert R.; Acostia, Roberto J.

2006-01-01

107

Technique for Solving Electrically Small to Large Structures for Broadband Applications  

NASA Technical Reports Server (NTRS)

Fast iterative algorithms are often used for solving Method of Moments (MoM) systems, having a large number of unknowns, to determine current distribution and other parameters. The most commonly used fast methods include the fast multipole method (FMM), the precorrected fast Fourier transform (PFFT), and low-rank QR compression methods. These methods reduce the O(N) memory and time requirements to O(N log N) by compressing the dense MoM system so as to exploit the physics of Green s Function interactions. FFT-based techniques for solving such problems are efficient for spacefilling and uniform structures, but their performance substantially degrades for non-uniformly distributed structures due to the inherent need to employ a uniform global grid. FMM or QR techniques are better suited than FFT techniques; however, neither the FMM nor the QR technique can be used at all frequencies. This method has been developed to efficiently solve for a desired parameter of a system or device that can include both electrically large FMM elements, and electrically small QR elements. The system or device is set up as an oct-tree structure that can include regions of both the FMM type and the QR type. The system is enclosed with a cube at a 0- th level, splitting the cube at the 0-th level into eight child cubes. This forms cubes at a 1st level, recursively repeating the splitting process for cubes at successive levels until a desired number of levels is created. For each cube that is thus formed, neighbor lists and interaction lists are maintained. An iterative solver is then used to determine a first matrix vector product for any electrically large elements as well as a second matrix vector product for any electrically small elements that are included in the structure. These matrix vector products for the electrically large and small elements are combined, and a net delta for a combination of the matrix vector products is determined. The iteration continues until a net delta is obtained that is within the predefined limits. The matrix vector products that were last obtained are used to solve for the desired parameter. The solution for the desired parameter is then presented to a user in a tangible form; for example, on a display.

Jandhyala, Vikram; Chowdhury, Indranil

2011-01-01

108

A new planar feed for slot spiral antennas  

NASA Technical Reports Server (NTRS)

This report presents a new planar, wideband feed network for a slot spiral antenna, and the subsequent design and performance of a VHF antenna utilizing this feed design. Both input impedance and radiation pattern measurements are presented to demonstrate the performance and usefulness of this feed. Almost all previous designs have utilized wire spirals, requiring bulky, non-planar feeds with separate baluns, and large absorbing cavities. The presented slot spiral antenna feed integrates the balun into the structure of the slot spiral antenna, making the antenna and feed planar. This greatly simplifies the design and construction of the antenna, in addition to providing repeatable accuracy. It also allows the use of a very shallow reflecting cavity for conformal applications. Finally, this feeding approach now makes many of the known miniaturization techniques viable options.

Nurnberger, M. W.; Volakis, J. L.

1995-01-01

109

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

110

Electrically-small quarter-wave, and resonant monopole elements with disk ground plans in free space  

Microsoft Academic Search

This paper extends previously reported results for a quarterwave monopole element on a disk ground plane in free space to include electrically-small and resonant elements. Numerical results are obtained by utilizing Richmond's method of moments computer program for disk ground planes in free space.

M. M. Weiner

1990-01-01

111

A reconfigurable plasma antenna  

SciTech Connect

An experiment aimed at investigating the antenna properties of different plasma structures of a plasma column as a reconfigurable plasma antenna, is reported. A 30 cm long plasma column is excited by surface wave, which acts as a plasma antenna. By changing the operating parameters, e.g., working pressure, drive frequency, input power, radius of glass tube, length of plasma column, and argon gas, single plasma antenna (plasma column) can be transformed to multiple small antenna elements (plasma blobs). It is also reported that number, length, and separation between two antenna elements can be controlled by operating parameters. Moreover, experiments are also carried out to study current profile, potential profile, conductivity profile, phase relations, radiation power patterns, etc. of the antenna elements. The effect on directivity with the number of antenna elements is also studied. Findings of the study indicate that entire structure of antenna elements can be treated as a phased array broadside vertical plasma antenna, which produces more directive radiation pattern than the single plasma antenna as well as physical properties and directivity of such antenna can be controlled by operating parameters. The study reveals the advantages of a plasma antenna over the conventional antenna in the sense that different antennas can be formed by tuning the operating parameters.

Kumar, Rajneesh [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Bora, Dhiraj [ITER Organisation, Cadarache 13108 (France)

2010-03-15

112

A Flexible Surface Description for Arbitrarily Shaped Dielectric Lens Antennas  

NASA Astrophysics Data System (ADS)

A method to efficiently describe arbitrarily shaped dielectric lens antennas based on spherical harmonics is proposed. It makes use of a Fourier-Laplace series and requires a low number of expansion coefficients, only. Symmetries can be included to impose special geometries or to further reduce the number of coefficients. The efficiency of the approach enables a fast optimization of the surface. This is particularly useful for electrically small lenses. Three exemplary lens designs based on different specifications are obtained through optimization. The manufacturing is discussed and the radiation characteristics are explored and validated through measurements.

Jaschke, Thomas; Rohrdantz, Benjamin; Jacob, Arne F.

2015-01-01

113

Ultra-small single-negative electric metamaterials for electromagnetic coupling reduction of microstrip antenna array.  

PubMed

We report initially the design, fabrication and measurement of using waveguided electric metamaterials (MTM) in the design of closely-spaced microtrip antenna arrays with mutual coupling reduction. The complementary spiral ring resonators (CSRs) which exhibit single negative resonant permittivity around 3.5GHz are used as the basic electric MTM element. For verification, two CSRs with two and three concentric rings are considered, respectively. By properly arranging these well engineered waveguided MTMs between two H-plane coupled patch antennas, both numerical and measured results indicate that more than 8.4 dB mutual coupling reduction is obtained. The mechanism has been studied from a physical insight. The electric MTM element is electrically small, enabling the resultant antenna array to exhibit a small separation (?o/8 at the operating wavelength) and thus a high directivity. The proposed strategy opens an avenue to new types of antenna with super performances and can be generalized for other electric resonators. PMID:23037347

Xu, He-Xiu; Wang, Guang-Ming; Qi, Mei-Qing; Zeng, Hui-Yong

2012-09-24

114

Review ofReview of AntennaAntenna  

E-print Network

Review ofReview of AntennaAntenna theorytheorytheorytheory Dr. Sandra CruzDr. Sandra CruzUniversity of Puerto Rico at Mayaguez What is an antenna?What is an antenna? An antenna is aAn antenna is a passive structurepassive structure thatthat serves as transition between aserves as transition between a transmission

Cruz-Pol, Sandra L.

115

Compact acoustic antenna design using labyrinthine metamaterials  

NASA Astrophysics Data System (ADS)

We present an effective design and architecture for a class of acoustic antennas in air. The work begins with a conformal transformation method that yields the preliminary design, which is constructed using an isotropic but inhomogeneous material. However, the desired material parameters have been unavailable until now. Here we show that by scaling up the refractive index and optimizing the geometry in the preliminary design, a series of square antennas can be achieved to exhibit an excellent beam-collimating effect. An important part of our strategy is that the device's thickness and material properties can be tailored easily to greatly facilitate its realization. It is also demonstrated that the proposed antenna can be made very thin and readily implemented using labyrinthine acoustic metamaterials.

Ren, Chunyu

2015-03-01

116

A Well-Conditioned Integral-Equation Formulation for Efficient Transient Analysis of Electrically Small Microelectronic Devices  

Microsoft Academic Search

A hierarchically regularized coupled set of time-domain surface and volume electric field integral-equations (TD-S-EFIE and TD-V-EFIE) for analyzing electromagnetic wave interactions with electrically small and geometrically intricate composite structures comprising perfect electrically conducting surfaces and finite dielectric volumes is presented. A classically formulated coupled set of TD-S- and V-EFIEs is shown to be ill-conditioned at low frequencies owing to the

Hakan Bagci; Francesco P. Andriulli; Francesca Vipiana; Giuseppe Vecchi; Eric Michielssen

2010-01-01

117

Microstrip patch antenna receiving array operating in the Ku band  

NASA Technical Reports Server (NTRS)

Microstrip patch antennas were first investigated from the idea that it would be highly advantageous to fabricate radiating elements (antennas) on the same dielectric substrate as RF circuitry and transmission lines. Other advantages were soon discovered to be its lightweight, low profile, conformability to shaped surfaces, and low manufacturing costs. Unfortunately, these same patches continually exhibit narrow bandwidths, wide beamwidths, and low antenna gain. This thesis will present the design and experimental results of a microstrip patch antenna receiving array operating in the Ku band. An antenna array will be designed in an attempt to improve its performance over a single patch. Most Ku band information signals are either wide band television images or narrow band data and voice channels. An attempt to improve the gain of the array by introducing parasitic patches on top of the array will also be presented in this thesis.

Walcher, Douglas A.

1996-01-01

118

EVOLUTION OF ANTENNA PERFORMANCE FOR APPLICATIONS IN THERMAL MEDICNE.  

PubMed

This presentation provides an overview of electromagnetic heating technology that has proven useful in clinical applications of hyperthermia therapy for cancer. Several RF and microwave antenna designs are illustrated which highlight the evolution of technology from simple waveguide antennas to spatially and temporally adjustable multiple antenna phased arrays for deep heating, conformal arrays for superficial heating, and compatible approaches for radiometric and magnetic resonance image based non-invasive thermal monitoring. Examples of heating capabilities for several recently developed applicators demonstrate highly adjustable power deposition that has not been possible in the past. PMID:23487445

Stauffer, P R; Maccarini, P F

2011-01-01

119

EVOLUTION OF ANTENNA PERFORMANCE FOR APPLICATIONS IN THERMAL MEDICNE  

PubMed Central

This presentation provides an overview of electromagnetic heating technology that has proven useful in clinical applications of hyperthermia therapy for cancer. Several RF and microwave antenna designs are illustrated which highlight the evolution of technology from simple waveguide antennas to spatially and temporally adjustable multiple antenna phased arrays for deep heating, conformal arrays for superficial heating, and compatible approaches for radiometric and magnetic resonance image based non-invasive thermal monitoring. Examples of heating capabilities for several recently developed applicators demonstrate highly adjustable power deposition that has not been possible in the past. PMID:23487445

Stauffer, P.R.; Maccarini, P.F.

2013-01-01

120

Conformal House  

E-print Network

We investigate the gauge dynamics of nonsupersymmetric SU(N) gauge theories featuring the simultaneous presence of fermionic matter transforming according to two distinct representations of the underlying gauge group. We bound the regions of flavors and colors which can yield a physical infrared fixed point. As a consistency check we recover the previously investigated conformal windows bounds when restricting to a single matter representation. The earlier conformal windows can be imagined to be part now of the new conformal house. We predict the nonperturbative anomalous dimensions at the infrared fixed points. We further investigate the effects of adding mass terms to the condensates on the conformal house chiral dynamics and construct the simplest instanton induced effective Lagrangian terms.

Thomas A Ryttov; Francesco Sannino

2009-06-01

121

Coherently combining antennas  

NASA Technical Reports Server (NTRS)

An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.

Dybdal, Robert B. (Inventor); Curry, Samuel J. (Inventor)

2009-01-01

122

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

123

Industrial Plasma Antennas  

Microsoft Academic Search

This presentation summarizes an extensive program on plasma antennas. Plasma antennas are just as effective as metal antennas. In addition, they can transmit, receive and reflect lower frequency signals while being transparent to higher frequency signals. When de-energized, they electrically disappear. Plasma noise does not appear to be a problem. New technology that has been developed include a method of

Igor Alexeff

2007-01-01

124

Modal impedances of planar, non-complementary, N-fold symmetric antenna structures  

Microsoft Academic Search

Planar N-arm rotationally symmetric antennas are commonly used in applications that demand wideband, multiple-mode, dual-polarization, and conformal geometries. Antennas included in this category are spirals, log-periodic dipole arrays, bow-tie antennas, and sinuous structures. An analytic expression for the modal impedances of these complementary planar structures has been available for many years. This paper extends the theory to non-complementary planar \\/V-fold

J. A. Huffman; T. Cencich

2005-01-01

125

Antenna theory: Analysis and design  

NASA Astrophysics Data System (ADS)

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

Balanis, C. A.

126

Synthesis of multiple shaped beam antenna patterns  

NASA Technical Reports Server (NTRS)

Results are presented of research into the problem of finding an excitation of a given antenna such that the desired radiation pattern is approximated to within acceptable limits. This is to be done in such a fashion that boundary conditions involving hardware limitations may be inserted into the problem. The intended application is synthesis of multiple shaped beam antennas. Since this is perhaps the most difficult synthesis problem an antenna engineer is likely to encounter, the approach taken was to include as a by-product capability for synthesizing simpler patterns. The synthesis technique has been almost totally computerized. The class of antennas which may be synthesized with the computer program are those which may be represented as planar (continuous or discrete) current distributions. The technique is not limited in this sense and could indeed by extended to include, for example, the synthesis of conformal arrays or current distributions on the surface of reflectors. The antenna types which the program is set up to synthesize are: line source, rectangular aperture, circular aperture, linear array, rectangular array, and arbitrary planar array.

Stutzman, W. L.; Coffey, E. L.

1973-01-01

127

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

128

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

129

Antenna Controller Replacement Software  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

130

A Compact Annular Ring Microstrip Antenna for WSN Applications  

PubMed Central

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

2012-01-01

131

PASS spacecraft antenna technology assessment  

Microsoft Academic Search

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

R. E. Freeland

1990-01-01

132

Spiral antenna irradiation into lossy media with Debye dispersion  

Microsoft Academic Search

This paper presents the analysis of single arm Archimedean spiral antennas radiating into a lossy medium (i.e. water) characterized by Debye dispersion. Conformal Finite Difference Time Domain (CFDTD) method is used for simulation. The error due to the staircase approximation of FDTD mesh is remedied by using CFDTD algorithm. The reflection coefficient simulation result with Debye dispersion is presented and

M.-R. Tofighi; A. Sunal

2008-01-01

133

Linearly tapered slot antenna circular array for mobile communications  

NASA Technical Reports Server (NTRS)

The design, fabrication and testing of a conformal K-band circular array is presented. The array consists of sixteen linearly tapered slot antennas (LTSA). It is fed by a 1:16 microstrip line power splitter via electromagnetic coupling. The array has an omni-directional pattern in the azimuth plane. In the elevation plane the beam is displaced above the horizon.

Simons, Rainee N.; Kelly, Eron; Lee, Richard Q.; Taub, Susan R.

1993-01-01

134

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

135

Phased array antenna control  

NASA Technical Reports Server (NTRS)

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

Doland, G. D. (inventor)

1978-01-01

136

Recent results for plasma antennas  

SciTech Connect

Plasma antennas are just as effective as metal antennas. They can transmit, receive, and reflect radio waves just as well as metal antennas. In addition, plasma generated noise does not appear to be a problem.

Alexeff, Igor; Anderson, Ted; Farshi, Esmaeil; Karnam, Naresh; Pulasani, Nanditha Reddy [Department of Electrical Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2008-05-15

137

Wide sector coverage antennas  

NASA Astrophysics Data System (ADS)

The general design and performance characteristics of transmit and receive antennas that are currently used in electronic warfare systems are reviewed. Among transmit antennas, three-to-one bandwidth, asymmetric-beam, and circularly polarized horns are discussed, as are extremely broadband monopoles and spiral antennas. In a discussion of receive antennas, attention is given to flat and conical spirals, including cavity-backed flat spirals operating over the 2.5-18 GHz range; log periodic dipoles; and biconical horns. Finally, the design configurations and performance of interferometer direction-finding systems are briefly discussed.

Yaw, D. F.

1984-09-01

138

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.

139

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

140

Turnstile slot antenna  

NASA Technical Reports Server (NTRS)

A turnstile slot antenna is disclosed, the antenna being for and integral with a spacecraft having a substantially cylindrical body portion. The antenna comprises a circumferential slot about the periphery of the spacecraft body portion with an annular wave guide cavity defining a radial transmission line disposed within the spacecraft body portion behind and in communication with the circumferential slot. Feed stubs and associated transmission apparatus are provided to excite the annular cavity in quadrature phase such that an omnidirectional, circularly polarized, rotating radiation pattern is generated. The antenna of the instant invention has utility both as a transmitting and receiving device, and ensures continuous telemetry and command coverage with the spacecraft.

Munson, R. E. (inventor)

1974-01-01

141

DIPLOMA THESIS VECTOR ANTENNA FOR  

E-print Network

Polarization 10 3 Design Considerations for the Vector Antenna 11 3.1 Vector Antenna 11 3.2 Determining.5 Antenna Loss Resistance 14 3.6 Determining the Operation Frequency for the Vector Antenna 16 3.7 Design.1 Mechanical Considerations for Design 19 4.2 The Cover of the Antenna 19 4.3 The material for the Antennas 20

142

Flexible sixteen monopole antenna array for microwave breast cancer detection.  

PubMed

Radar based microwave imaging (MI) has been widely studied for breast cancer detection in recent times. Sensing dielectric property differences of tissues over a wide frequency band has been made possible by ultra-wideband (UWB) techniques. In this paper, a flexible, compact monopole antenna on a 100 ?m Kapton polyimide is designed, using a high frequency structure simulator (HFSS), to be in contact with biological breast tissues over the 2-5GHz frequency range. The antenna parameters are optimized to obtain a good impedance match over the required frequency range. The designed antenna size is 18mm × 18mm. Further, a flexible conformal 4×4 ultra-wideband antenna array, in a format similar to that of a bra, was developed for a radar-based breast cancer detection system. PMID:25570813

Bahrami, H; Porter, E; Santorelli, A; Gosselin, B; Popovic, M; Rusch, L A

2014-01-01

143

Radiation by cavity-backed antennas on a circular cylinder  

NASA Technical Reports Server (NTRS)

Conformal antenna arrays are popular antennas for aircraft, spacecraft and land vehicle platforms due to their inherent low weight, cost and drag properties. However, to date there has been a dearth of rigorous analytical or numerical solutions to aid the designer. In fact, it has been common practice to use limited measurements and planar approximations in designing such non-planar antennas. The finite element-boundary integral method is extended to radiation by cavity-backed structures in an infinite, metallic cylinder. The formulation is used to investigate the effect of cavity size on the radiation pattern for typical circumferentially and axially polarized patch antennas. Curvature effect on the gain, pattern shape, and input impedance is also studied. Finally, the accuracy of the FE-BI approach for a microstrip patch array is demonstrated.

Kempel, Leo C.; Volakis, John L.; Sliva, Randy

1994-01-01

144

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

145

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

146

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

147

Satellite horn antennas design  

Microsoft Academic Search

Telecommunication satellite horn antennas require now-a-days more and more stringent requirements based mainly in the increased bandwidth necessary to accommodate more transponders to increase the capacity of the new satellite services. In this aspect horn antennas play a key role in the development of wider bandwidth services on board satellites because they are usually the reason that limits bandwidth in

Jorge Teniente; Ramón Gonzalo; Carlos del Río

2009-01-01

148

Logarithmically periodic antenna designs  

Microsoft Academic Search

Research on new types of broadband logarithmically periodic antenna structures is reported. The antennas have pattern and impedance characteristics which are essentially independent of frequency over theoretically unlimited bandwidths. Bandwidths of ten to one are readily achieved in practice. Structures are described which provide linearly polarized omnidirectional, bidirectional and unidirectional patterns as well as circularly polarized bidirectional and unidirectional patterns.

R. H. DuHamel; F. R. Ore

1958-01-01

149

Bidirectional zoom antenna  

NASA Technical Reports Server (NTRS)

Antenna comprises two parabolic cylinders placed orthogoanlly to each other. One cylinder serves as main reflector, and the other as subreflector. Cylinders have telescoping sections to vary antenna beamwidth. Beamwidth can be adjusted in elevation, azimuth, or both. Design has no restriction as to choice of polarization.

Schmidt, R. F.

1975-01-01

150

Infrared and submillimetre antennas  

Microsoft Academic Search

Investigations have been conducted of both cat-whisker and planar antennas. Some attempt has been made to proceed mathematically, but the difficulties are great. A simpler approach is to use modeling at microwave frequencies. This technique is often used at lower frequencies, and it has been demonstrated as a tool for submillimeter antenna design by Mizuno et al. (1977). Experiments indicate

D. B. Rutledge; S. E. Schwarz; A. T. Adams

1978-01-01

151

Types of Antennae  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the different types of antennae found on arthropods. The single Web page, which can be easily printed for use at field sites or in the lab, shows 8 types of antennae.

152

ARABSAT communication antennas  

Microsoft Academic Search

The communication antennas of the ARABSAT spacecraft are described, and problems associated with antenna spacecraft integration are discussed. The payload consists of 25 C\\/C band transponders providing 8000 simultaneous telephone circuits plus seven TV programs or an equivalent traffic in other kinds of fixed services, and one C\\/S transponder for semidirect television. EIRP (equivalent isotropically radiated power) performances are 31

P. Vizier

1989-01-01

153

Dielectric waveguide antenna  

Microsoft Academic Search

Investigations have continued into developing design criteria for a dielectric waveguide line source antenna. The Marcatili analysis has proven to be a reliable guide for the transmission line design. There is, however, no practical design information available permitting the synthesis of a symmetrical amplitude taper along a grooved dielectric waveguide antenna. This investigation presents a measurement procedure that will permit

J. Borowick; W. Bayha; R. A. Stern; R. W. Babbitt

1982-01-01

154

Deformations in VLBI antennas  

NASA Technical Reports Server (NTRS)

A study is presented of deformations in antennas with the emphasis on their influence on VLBI measurements. The GIFTS structural analysis program has been used to model the VLBI antenna in Fairbanks (Alaska). The report identifies key deformations and studies the effect of gravity, wind, and temperature. Estimates of expected deformations are given.

Clark, T. A.; Thomsen, P.

1988-01-01

155

GPS antenna designs  

NASA Technical Reports Server (NTRS)

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

Laube, Samuel J. P.

1987-01-01

156

Uniplanar Wideband Quasi Yagi Antenna for Multiple Antenna Channel Measurements  

E-print Network

High Frequency Structure Simulator (HFSS) software. The antenna designed to form part of an antenna as a reflector. Important features of this antenna are its simple structure and capability of being linearly structure Figure 1 shows a schematic geometry of the uniplanar quasi-Yagi antenna. It consists of a printed

Haddadi, Hamed

157

Characteristics of microstrip muscle-loaded single-arm archimedean spiral antennas as investigated by FDTD numerical computations  

Microsoft Academic Search

The radiation characteristics and mode of operation of single-arm, groundplane backed, Archimedean spiral antennas are investigated by means of conformal finite difference time domain numerical analysis. It is shown that this antenna type may be categorized as a well-matched, broadband, circularly polarized traveling wave structure that can be fed directly by nonbalanced coaxial networks. The study further concentrates on relevant

Svein Jacobsen; Hans Olav Rolfsnes; Paul R. Stauffer

2005-01-01

158

UHF coplanar-slot antenna for aircraft-to-satellite data communications  

NASA Technical Reports Server (NTRS)

A lightweight low drag coplanar slot antenna was developed for use on commercial jet aircraft that will provide upper hemisphere coverage in the UHF band at frequencies of 402 and 468 MHz is described. The antenna is designed to transmit meteorological data from wide body jet aircraft to ground users via synchronous meteorological data relay satellites. The low profile antenna (23.5 cm wide by 38.1 cm long slot by 1.9 cm high) is a conformal antenna utilizing the coplanar approach with the advantages of broad frequency bandwidth and improved electrical integrity over wide range of temperature. The antenna is circular polarized, has anon axis gain of near +2.5 dB, and a HPBW greater than 90 deg. Areas discussed include antenna design, radiation characteristics, flight testing, and system performance.

Myhre, R. W.

1979-01-01

159

Antenna Location Optimization for Circular-Layout Distributed Antenna Systems  

NASA Astrophysics Data System (ADS)

The distributed antenna system (DAS) offers significant power savings but only if the antennas are properly located. In this letter, we convert antenna location optimization to the codebook design problem. For the widely studied circular-layout DAS with uniform user distribution, we derive closed-form expressions for antenna locations that yield near-optimal performance. For more general user distribution and antenna topology, the codebook design algorithms can provide numerical optimization results with acceptable performance and low complexity.

Wang, Xinzheng; Zhu, Pengcheng; Chen, Ming

160

Calibration of circular loop antennas  

Microsoft Academic Search

The calibration of a measuring loop antenna means assigning an antenna factor K for each frequency in the entire measurement band. Such a loop antenna factor can be found either by calculating the impedances of the loop, or by using a well-defined standard magnetic field of a transmitting antenna. For both methods, it is necessary to obtain an accurate relation

Aydin Aykan

1998-01-01

161

Autonomous omnidirectional spacecraft antenna system  

NASA Technical Reports Server (NTRS)

The development of a low gain Electronically Switchable Spherical Array Antenna is discussed. This antenna provides roughly 7 dBic gain for receive/transmit operation between user satellites and the Tracking and Data Relay Satellite System. When used as a pair, the antenna provides spherical coverage. The antenna was tested in its primary operating modes: directed beam, retrodirective, and Omnidirectional.

Taylor, T. H.

1983-01-01

162

Spiral microstrip antenna with resistance  

Microsoft Academic Search

The present invention relates to microstrip antennas, and more particularly to wide bandwidth spiral antennas with resistive loading. A spiral microstrip antenna having resistor element embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter

David G. Shively

1994-01-01

163

RF MEMS Based Reconfigurable Antennas  

NASA Technical Reports Server (NTRS)

The presentation will first of all address the advantages of RF MEMS circuit in antenna applications and also the need for electronically reconfigurable antennas. Next, discuss some of the recent examples of RF MEMS based reconfigurable microstrip antennas. Finally, conclude the talk with a summary of MEMS antenna performance.

Simons, Rainee N.

2004-01-01

164

SPS antenna pointing control  

NASA Technical Reports Server (NTRS)

The pointing control of a microwave antenna of the Satellite Power System was investigated emphasizing: (1) the SPS antenna pointing error sensing method; (2) a rigid body pointing control design; and (3) approaches for modeling the flexible body characteristics of the solar collector. Accuracy requirements for the antenna pointing control consist of a mechanical pointing control accuracy of three arc-minutes and an electronic phased array pointing accuracy of three arc-seconds. Results based on the factors considered in current analysis, show that the three arc-minute overall pointing control accuracy can be achieved in practice.

Hung, J. C.

1980-01-01

165

Robust Hybrid Finite Element Methods for Antennas and Microwave Circuits  

NASA Technical Reports Server (NTRS)

One of the primary goals in this dissertation is concerned with the development of robust hybrid finite element-boundary integral (FE-BI) techniques for modeling and design of conformal antennas of arbitrary shape. Both the finite element and integral equation methods will be first overviewed in this chapter with an emphasis on recently developed hybrid FE-BI methodologies for antennas, microwave and millimeter wave applications. The structure of the dissertation is then outlined. We conclude the chapter with discussions of certain fundamental concepts and methods in electromagnetics, which are important to this study.

Gong, J.; Volakis, John L.

1996-01-01

166

Field expressions for a circular loop antenna in terms of a new set of functions  

Microsoft Academic Search

An exact expression for the fields produced by an electrically small loop antenna is obtained in terms of a series involving a new set of functions, namely en(?,?)=(1?2?)?02?cos(n&PHgr;)sin[?(1?2?cos&PHgr;)1?2]d&PHgr; and fn(?,?)=(1?2?)×?02?cos(n&PHgr;)cos[?(1?2?cos&PHgr;)1?2]d&PHgr;, where ? ?

Manuel A. Huerta; Guillermo Gonzalez

1972-01-01

167

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

168

Dielectric Covered Planar Antennas  

NASA Technical Reports Server (NTRS)

An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.

Llombart Juan, Nuria (Inventor); Lee, Choonsup (Inventor); Chattopadhyay, Goutam (Inventor); Gill, John J. (Inventor); Skalare, Anders J. (Inventor); Siegel, Peter H. (Inventor)

2014-01-01

169

Coaxial phased array antenna  

NASA Technical Reports Server (NTRS)

A coaxial antenna array for communicating circularly polarized electromagnetic radiation is disclosed. A pair of open ended antenna cavities is coaxially constructed and operates by excitation of linear radiation elements arranged within each of the cavities. A pair of crossed dipole radiation devices is centered within the inner cavity and operated by means of a phase shifting network circuit to transmit as well as receive circularly polarized radiation. Four monopole radiation devices are symmetrically arranged to operate in the outer cavity in phase quadrature by means of the phase shifting network circuit to both transmit and receive circularly polarized electromagnetic radiation. Combined operation of the two antenna cavities with a 180 deg phase differential between the fields related to the two antenna cavities provides a broad beam, relatively wide frequency bandwidth communication capability. Particular embodiments disclosed feature a generally square cavity array as well as a circular cavity array.

Ellis, H., Jr. (inventor)

1980-01-01

170

Antenna pattern study  

NASA Technical Reports Server (NTRS)

Prediction of antenna radiation patterns has long been an important function in the design of command, communication, and tracking systems for rocket vehicles and spacecraft. An acceptable degree of assurance that a radio link will provide the required quality of data or certainty of correct command execution must be acquired by some means if the system is to be certified as reliable. Two methods have been used to perform this function: (1) Theoretical analysis, based on the known properties of basic antenna element types and their behavior in the presence of conductive structures of simple shape, and (2) Measurement of the patterns on scale models of the spacecraft or rocket vehicle on which the antenna is located. Both of these methods are ordinarily employed in the antenna design process.

Harper, Warren

1988-01-01

171

Plural beam antenna  

NASA Technical Reports Server (NTRS)

An antenna capable of deriving several beams about a single boresight axis including a focusing means, such as a parabolic reflector or a lens is described. Plural arrays, each including plural radially aligned antenna elements extending from the boresight axis, are located in proximity to a focal point for the focusing means. The elements of the plural arrays are independently excited as each of the arrays is independently rotated about the boresignt axis.

Keller, G. C.; Maxwell, M. S.; Dod, L. R. (inventors)

1973-01-01

172

Polarized Antenna Splitting Functions  

SciTech Connect

We consider parton showers based on radiation from QCD dipoles or 'antennae'. These showers are built from 2 {yields} 3 parton splitting processes. The question then arises of what functions replace the Altarelli-Parisi splitting functions in this approach. We give a detailed answer to this question, applicable to antenna showers in which partons carry definite helicity, and to both initial- and final-state emissions.

Larkoski, Andrew J.; Peskin, Michael E.; /SLAC

2009-10-17

173

Optical antenna gain. II - Receiving antennas  

NASA Technical Reports Server (NTRS)

Expressions are developed for the gain of a centrally obscured, circular optical antenna used as the collecting and focusing optics in a laser receiver, involving losses due to (1) incoming light blockage by central obscuration, (2) energy spillover at the detector, and (3) the effect of local oscillator distribution in the case of heterodyne or homodyne detection. Numerical results are presented for direct detection and for three types of local oscillator distribution (uniform, Gaussian, and matched).

Degnan, J. J.; Klein, B. J.

1974-01-01

174

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

NASA Technical Reports Server (NTRS)

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.

1989-01-01

175

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

176

47 CFR 73.753 - Antenna systems.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna systems. 73.753 Section 73.753...International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be...

2014-10-01

177

47 CFR 73.753 - Antenna systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna systems. 73.753 Section 73.753...International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be...

2010-10-01

178

47 CFR 95.1013 - Antennas.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antennas. 95.1013 Section 95.1013 ...General Provisions § 95.1013 Antennas. (a) The maximum allowable...AMTS stations must employ directional antennas. (c) Antennas used with LPRS...

2012-10-01

179

47 CFR 95.1013 - Antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antennas. 95.1013 Section 95.1013 ...General Provisions § 95.1013 Antennas. (a) The maximum allowable...AMTS stations must employ directional antennas. (c) Antennas used with LPRS...

2013-10-01

180

47 CFR 73.753 - Antenna systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna systems. 73.753 Section 73.753...International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be...

2013-10-01

181

47 CFR 73.753 - Antenna systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna systems. 73.753 Section 73.753...International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be...

2011-10-01

182

47 CFR 73.753 - Antenna systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna systems. 73.753 Section 73.753...International Broadcast Stations § 73.753 Antenna systems. All international broadcasting stations shall operate with directional antennas. Such antennas shall be...

2012-10-01

183

47 CFR 95.1013 - Antennas.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antennas. 95.1013 Section 95.1013 ...General Provisions § 95.1013 Antennas. (a) The maximum allowable...AMTS stations must employ directional antennas. (c) Antennas used with LPRS...

2011-10-01

184

47 CFR 95.1013 - Antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antennas. 95.1013 Section 95.1013 ...General Provisions § 95.1013 Antennas. (a) The maximum allowable...AMTS stations must employ directional antennas. (c) Antennas used with LPRS...

2014-10-01

185

Octocopter based Calibration of the Butterfly Antenna  

E-print Network

Mechanical Structure of the Butterfly Antenna 45 5.1 Description of the Butterfly AntennaOctocopter based Calibration of the Butterfly Antenna for the Pierre Auger Observatory von Raphael.4 AERA Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4 Antenna

Erdmann, Martin

186

Development of Leaky Wave Antennas for Layered Ridge Dielectric Waveguide  

NASA Technical Reports Server (NTRS)

The millimeter wave, especially above 100 GHz, and the submillimeter wave frequency spectrum offers the possibility for narrow-beam, high-resolution antennas which are critical for high definition radars required for space debris tracking, airport ground avoidance radars, and missile tracking. In addition, the frequency which most atmospheric constituents may be detected lie in this part of the frequency spectrum. Therefore, the development of electronic components for millimeter/submillimeter wave passive sensors is required for environmental monitoring of the Earth's atmosphere. Typical microwave transmission lines such as microstrip and coplanar waveguide rely on two or more electrical conductors to concentrate and guide the electromagnetic energy. Unfortunately, the surface resistance of the conductors increases as the square root of frequency. In addition, the circuit dimensions must be decreased with increasing frequency to maintain a single mode transmission line which further increases the conductor loss. An alternative family of transmission lines are formed from two or more insulating materials and rely on the differences in the permittivities between the two materials to guide the wave. No metal conductors are required although some dielectric waveguides do utilize a metallic ground plane to facilitate the interconnections of active electrical elements or to reduce the transmission line size. Examples of such transmission lines are image guides, insulated image guides, trapped image guides, ridge guide, and layered ridge dielectric waveguide (LRDW). Although most dielectric waveguides have dimensions on the order of lambda to provide sufficient field confinement, the LRDW has been shown to provide good field confinement for electrically small lines. This offers an advantage in circuit integration. It has been shown that a periodic array of metallic strips placed either along or on top of a dielectric waveguide forms an effective radiator. This antenna is easy to fabricate and there is good background of microstrip type antenna design information in the literature. This paper reports the development of the first frequency scanning antenna fed by a LRDW.

Ponchak, George E.; Katehi, Linda P. B.

1993-01-01

187

Conformal Tachyons  

NASA Astrophysics Data System (ADS)

We study tachyons conformally coupled to the background geometry of a Milne universe. The causality of superluminal signal transfer is scrutinized in this context. The cosmic time of the comoving frame determines a distinguished time order for events connected by superluminal signals. An observer can relate his rest frame to the galaxy frame, and compare so the time order of events in his proper time to the cosmic time order. All observers can in this way arrive at identical conclusions on the causality of events connected by superluminal signals. An unambiguous energy concept for tachyonic rays is defined by means of the cosmic time of the comoving reference frame, without resorting to an antiparticle interpretation. On that basis we give an explicit proof that no signals can be sent into the past of observers. Causality violating signals are energetically forbidden, as they would have negative energy in the rest frame of the emitting observer. If an observer emits a superluminal signal, the tachyonic response of a second observer cannot reach him prior to the emission, i.e. no predetermination can occur.

Tomaschitz, Roman

188

View of Antenna #1 (foreground), and Antenna #2 surface doors. ...  

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

View of Antenna #1 (foreground), and Antenna #2 surface doors. Image looking northeast - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

189

Antenna cab interior showing waveguide from external parabolic antenna (later ...  

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

Antenna cab interior showing waveguide from external parabolic antenna (later addition), looking north. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

190

Antenna cab interior showing equipment rack and fiberglass antenna panels, ...  

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

Antenna cab interior showing equipment rack and fiberglass antenna panels, looking southeast. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

191

Antenna cab interior showing equipment rack and fiberglass antenna panels, ...  

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

Antenna cab interior showing equipment rack and fiberglass antenna panels, looking west. - Western Union Telegraph Company, Jennerstown Relay, Laurel Summit Road off U.S. 30, Laughlintown, Westmoreland County, PA

192

System consideration, design approach and test of a low gain spherical coverage antenna for large space vehicles  

NASA Technical Reports Server (NTRS)

A fixed beam array antenna approach is proposed to meet the omnidirectional receiving and transmitting requirements of LST (Large Space Telescope). The proposed method uses an antenna of known performance and scales the size and frequency to conform with the LST 1/5-th scale model. The simplification that the approach provides over switching antenna elements on board the LST or switching from the ground by frequency diversity makes it worthy of consideration against the factors of performance, cost, reliability, and operations complexity. For LST applications, the system capabilities, requirements, and margins are summarized. The areas to be covered by further investigations into the proposed LST antenna are noted.

Ferguson, R. E.; Patterson, T. D.; Moreno, M. R.

1975-01-01

193

Uniplanar Wideband Quasi Yagi Antenna for Multiple Antenna Channel Measurements  

Microsoft Academic Search

Uniplanar quasi Yagi antenna has gained considerable attention recently as a method of producing a broad bandwidth antenna array with a well defined end-fire radiation pattern. An important advantage of the novel quasi-Yagi antenna designed in the X-band is its ability to be scaled linearly to any frequency band. This paper presents simulation results of a scaled quasi-Yagi antenna designed

M. Abdalla; S. Salous

194

Aperture excited dielectric antennas  

NASA Technical Reports Server (NTRS)

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

1974-01-01

195

View of antenna tunnel end. Right to Antenna Silo #1, ...  

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

View of antenna tunnel end. Right to Antenna Silo #1, left to Antenna Silo #2 - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

196

View north of the antenna array, note the communications antenna ...  

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

View north of the antenna array, note the communications antenna in the middleground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

197

Choked Gaussian antenna: extremely low sidelobe compact antenna design  

Microsoft Academic Search

A new concept of a really compact corrugated horn antenna for global coverage with very low sidelobe and cross-polar level and quite wide bandwidth is presented in this letter. This consists on the concatenation of a choke antenna together with a Gaussian profile horn antenna. A comparison of the performances of this horn design versus other author designs is included.

Jorge Teniente; David Goñi; Ramón Gonzalo; C. Del-Rio

2002-01-01

198

Structural synthesis of spiral antennas  

NASA Astrophysics Data System (ADS)

This article discusses alternative designs of helical antennas used in space vehicles. The dependence of the beam shape on the number of approaches and the mode of excitation of helical antennas is shown.

Prigoda, B. A.

2013-12-01

199

PASS Spacecraft Antenna Technology Assessment  

NASA Technical Reports Server (NTRS)

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.

1990-01-01

200

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

201

UHF coplanar-slot antenna for aircraft-to-satellite data communications  

NASA Technical Reports Server (NTRS)

The initiative for starting the Aircraft-to-Satellite Data Relay (ASDAR) Program came from a recognition that much of the world's weather originates in the data sparse area of the tropics which are primarily ocean. The ASDAR system consists of (1) a data acquisition and control unit to acquire, store and format these data; (2) a clock to time the data sampling and transmission periods; and (3) a transmitter and low-profile upper hemisphere coverage antenna to relay the formatted data via satellite to the National Weather Service ground stations, as shown schematically. The low-profile antenna is a conformal antenna based on the coplanar-slot approach. The antenna is circular polarized and has an on-axis gain of nearly 2.5 dB and a HPBW greater than 90 deg. The discussion covers antenna design, radiation characteristics, flight testing, and system performance.

Myhre, R. W.

1979-01-01

202

Concepts and cost trade-offs for land vehicle antennas in satellite mobile communications  

NASA Technical Reports Server (NTRS)

Several antenna design concepts, operating at UHF (821 to 825 MHz transmit and 866 to 870 MHz receive bands), with gain ranging between 6 and 12 dBic, that are suitable for land mobile vehicles are presented. The antennas may be used within CONUS and ALASKA to communicate to and from a geosynchronous satellite. Depending on the type of steering mechanism, the antennas are broken down into three categories; (1) electronically scanned arrays with phase shifters, (2) electronically switched arrays with switchable power dividers/combiners, and (3) mechanically steered arrays. The operating characteristics of two of these design concepts, one a conformal antenna with electronic beam steering and the other a nonconformal design with mechanical steering, were evaluated with regard to two and three satellite system. Cost estimates of various antenna concepts were made and plotted against their overall gain performance.

Haddad, H. A.

1948-01-01

203

A 96-antenna radioheliograph  

NASA Astrophysics Data System (ADS)

Here we briefly present some design approaches for a multifrequency 96-antenna radioheliograph. The configuration of the array antenna, transmission lines and digital receivers is the main focus of this work. The radioheliograph is a T-shaped centrally condensed radiointerferometer operating in the frequency range 4-8 GHz. The justification for the choice of such a configuration is discussed. The signals from antennas are transmitted to a workroom by analog optical links. The dynamic range and phase errors of the microwave-over-optical signal are considered. The signals after downconverting are processed by digital receivers for delay tracking and fringe stopping. The required step of delay tracking and data rates are considered. Two 3-bit data streams (I and Q) are transmitted to a correlator with the transceivers embedded in Field Programmed Gate Array chips and with PCI Express cables.

Lesovoi, Sergey V.; Altyntsev, Alexander T.; Ivanov, Eugene F.; Gubin, Alexey V.

2014-07-01

204

Logarithmic Conformal Field Theory  

E-print Network

#12;#12;Aspects of Logarithmic Conformal Field Theory Der Fakult¨at f¨ur Mathematik und Physik der various aspects of logarithmic conformal field theories (LCFTs). After recalling some important definitions and relations of (logarithmic) conformal field theories we study possible extensions of conformal

Flohr, Michael

205

A Non-Pyramidal Rectangular-to-Trough Waveguide Transition and Pattern Reconfigurable Trough Waveguide Antenna  

E-print Network

of larger system components such as antennas, whose efficiency and performance is predominantly dependent on their effective aperture size. Antenna designs such as microstrip patches and planar inverted F-antennas (PIFAs) have led to conformal planar... ll as a contin ight) make ith vertical an and Maest hase velocit the rotation vary the hei e continuo iven by (25 he free spac ade partial ain beam fo n. In this pr p and using uous asymm the TWA a d horizontal ri reported y...

Loizou, Loizos

2012-02-14

206

Anechoic chamber wideband antenna measurements  

Microsoft Academic Search

The method is considered which consists of measurements of output antenna signals on a number of frequencies and Fourier transformation of data into time domain for separation of own antenna field and interference fields. The results of testing at serial facility for antenna measurements in an anechoic chamber are presented as for diagnosis of scattered fields, as for improvement of

A. V. Kalinin

2006-01-01

207

Antenna design: a crystallographical approach  

Microsoft Academic Search

The goal of this thesis was to design a switched beam antenna by applying the principles of crystallography. The main benefit of this approach is that simple design equations can be derived from crystallography and readily applied to the design of a steerable beam antenna. Before using equations from crystallography in an antenna design, the equations are first verified. One

Luke MacVicker Snow

2011-01-01

208

Antenna diversity in mobile communications  

Microsoft Academic Search

The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of

R. G. Vaughan; J. B. Andersen

1987-01-01

209

The JPL mechanically steered antenna  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory has designed and developed a mechanically steered antenna for tracking satellites in a mobile environment. This antenna was used to track an L-band beacon on the MARISAT satellite. A description of the antenna and the results of the satellite experiment are given.

Berner, Jeff B.; Bell, David J.

1988-01-01

210

Antenna Position Calibration Melvyn Wright  

E-print Network

antenna positions. SELFCAL can include known source structure in the quasars. The baseline observationsAntenna Position Calibration Melvyn Wright Radio Astronomy laboratory, University of California, Berkeley, CA, 94720 ABSTRACT This memo summarizes the antenna position calibration used at Hat Creek

211

Satellite communication antenna technology  

NASA Technical Reports Server (NTRS)

A general overview of current technology in the field of communication satellite antennas is presented. Among the topics discussed are: the design of multiple beam systems; frequency reuse; and polarization control of antenna measurements. Consideration is also given to: contour beam synthesis; dual shaped reflector synthesis; beam shaping; and offset reflector design. The applications of the above technologies to present and future generations of communications satellites is considered, with emphasis given to such systems as: the Intelsats; the Defense Satellite Communications System, (DSCS-III); Satellite Business System (SBS), and Comstar.

Mittra, R. (editor); Imbriale, W. A. (editor); Maanders, E. J. (editor)

1983-01-01

212

Design considerations for an archimedean slot spiral antenna  

NASA Technical Reports Server (NTRS)

The design goal is to develop a 118-157 MHz, vertically polarized, low-profile (or conformal) antenna as a replacement for VHF AM blade antennas on aircraft. This design is to be arrived at by scaling the dimensions of an antenna designed for a center frequency of 1.1 GHz. The design prior to scaling may have the following maximum dimensions: diameter less than 3.70 in. and thickness less than 0.50 in. Although a four-arm spiral design was originally suggested, a two-arm spiral may also be used, as both mode-1 and mode-2 (sum and difference) radiation patterns aren't required. While a four-arm spiral can easily be designed should both sum and difference patterns be required, the two-arm design will provide the required sum pattern and simplify the design problem somewhat: only one feed is required, and the feed area geometry is more straightforward. Polarization requirements dictate that a slot spiral be used, as opposed to a wire spiral. Two similar radiating structures were considered. The first is the standard archimedean spiral antenna. The second is a hollow archimedean spiral antenna, essentially a standard archimedean spiral with the inner portion removed.

Nurnberger, Michael W.; Volakis, John L.

1995-01-01

213

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.

214

Offset unfurlable antenna concepts  

Microsoft Academic Search

A design definition study for an unfurlable offset antenna applicable to a wide mission spectrum of communication satellites was carried out. A radial rib reflector concept with auxiliary adjustment ribs, and a three dimensional scissors truss concept were considered. The radial rib reflector is seen to provide the greatest versatility. The foldable ribs can be deployed and latched up by

H. Kellermeier; W. Schaefer; H. Vorbrugg

1984-01-01

215

Antenna array research  

NASA Technical Reports Server (NTRS)

Antenna array research on electromagnetic field problems in inhomogeneous media is presented along with characteristics of the Eaton lens. Comparisons are given of the radiation pattern and directivity of small Luneburg lens with a homogeneous lens. References and figure captions on radiation patterns are included.

Tai, C.

1973-01-01

216

Visualizing antenna design spaces  

Microsoft Academic Search

This paper describes a long-term project exploring advanced visual interfaces for antenna design. MERL developed three suc- cessive prototypes that embodied an evolution towards larger scales and more concrete semantics for visualization of large sets of candidate designs and then winnowing them down. We experi- mented with multidimensional scaling and then collective line graphs before settling on linked scatterplots to

Kent Wittenburg; Tom Lanning; Darren Leigh; Kathy Ryall

2008-01-01

217

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

218

Conformal array design with transformation electromagnetics  

NASA Astrophysics Data System (ADS)

We apply the theory of transformation electromagnetics to source arrays and show that a complex conformal antenna array can be made to behave like a geometrically different array when surrounded with a properly designed transformation electromagnetics medium. Numerical simulations are presented to show how a nonuniform circular array can be made to radiate and receive as a uniformly spaced linear array. In this way, transformation electromagnetics provides a method by which all of the advantages of simple arrays in array processing, such as beamforming, can be retained in an array whose elements are constrained to a complex geometry.

Popa, Bogdan-Ioan; Allen, Jeffery; Cummer, Steven A.

2009-06-01

219

Mobile terminal antennas for helicopters  

NASA Technical Reports Server (NTRS)

In this paper, the feasibility of using an L-band low gain antenna (LGA) as a mobile terminal antenna for helicopters is described. The objective is to select the lowest cost antenna system which can be easily mounted on a helicopter and capable of communicating with a geosynchronous satellite. To ensure that all the antenna options are being considered, the steerable high gain reflector and medium gain array antennas as well as LGA are studied and compared in an exhaustive survey. The high gain reflector antenna in L-band is usually very large in size and heavy in weight. In addition, a bulky and expensive tracking system is needed to steer the antenna beam to the satellite direction. The medium gain antennas (including mechanically and electronically steered arrays) are also more expensive and less reliable than an LGA due to the addition of a beam steering system to track the satellite. The omni-directional LGA is simple, reliable, and inexpensive. It is typically ten times smaller than the medium gain antenna. This makes the position, selection, and mounting on the helicopter relatively easier. Therefore, the LGA is selected as a mobile terminal antenna for helicopters. Among the many LGA's (cross-dipole, helix, spiral, and slot antennas), the helix antenna is the most inexpensive. One can also change the size, shape, or pitch angle of the helix to optimize the gain in the desired direction. Therefore, the helix antenna is selected for further study. Both 2-arm and 4-arm helices are studied theoretically and experimentally to determine the antenna's performance and the scattering effects from the helicopter body and the blades. The multipath, Doppler, and Doppler rate issues as well as the periodic fading effects caused by the helicopter rotor blades will be briefly discussed in the paper.

Wu, Te-Kao; Farazian, K.; Golshan, N.; Divsalar, D.; Hinedi, S.; Woo, K.

1993-01-01

220

Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling  

NASA Technical Reports Server (NTRS)

As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we explored the possibility of developing these arrays in thin, flexible form to make conformable antennas.

Meador, Mary Ann B.; Miranda, Felix A.

2014-01-01

221

Fake conformal symmetry in conformal cosmological models  

NASA Astrophysics Data System (ADS)

We examine the local conformal invariance (Weyl invariance) in tensor-scalar theories used in recently proposed conformal cosmological models. We show that the Noether currents associated with Weyl invariance in these theories vanish. We assert that the corresponding Weyl symmetry does not have any dynamical role.

Jackiw, R.; Pi, So-Young

2015-03-01

222

Optimization of a dual concentric conductor antenna for superficial hyperthermia applications.  

PubMed

Dual concentric conductor antennas (DCCs) have been proposed as effective radiators for microwave hyperthermia applications, due to simplicity of construction from flexible printed circuit board (PCB) material. With proper design, the power deposition (SAR) pattern is uniform across the DCC. The effect of a single antenna can be combined in conformal nonphased arrays to form a region of nearly flat temperature distribution over a large area down to 1-1.5 cm depth. In the past, DCC antenna performance was analyzed using in-house FDTD software. Recently available electromagnetic simulation software provides reduced simulation time, increased accuracy and a user friendly interface with the ability to sweep design parameters to achieve critical optimization goals. More detail on antenna loading conditions provides enhanced design accuracy by accounting for second order effects neglected in previous modeling. In particular, recent design efforts have focused on improving antenna efficiency and reducing losses and reflections in the feedline network. A second challenge involves measurement of antenna properties in conditions more similar to the treatment environment, since temperature and loading condition affect antenna radiation and thus design requirements. We present the challenges of both antenna design and characterization, along with preliminary results of recent design improvements. PMID:17270785

Maccarini, Paolo F; Rolfsnes, Hans-Olav; Neuman, Daniel; Stauffer, Paul

2004-01-01

223

JPL Large Advanced Antenna Station Array Study  

NASA Technical Reports Server (NTRS)

In accordance with study requirements, two antennas are described: a 30 meter standard antenna and a 34 meter modified antenna, along with a candidate array configuration for each. Modified antenna trade analyses are summarized, risks analyzed, costs presented, and a final antenna array configuration recommendation made.

1978-01-01

224

Compact antenna structures for mobile handsets  

Microsoft Academic Search

In this paper, novel compact antenna structures for mobile handsets are studied. The antennas are based on non-resonant coupling elements, which are used to optimally couple to the characteristic wavemodes of the chassis. The resonances for the antenna structures are created with matching circuits. Two different antenna models are designed based on the novel antenna structure. From each model, single-band

Juha Villanen; Jani Ollikainen; Outi Kivekäs; Pertti Vainikainen

2003-01-01

225

Microstrip antenna couplers and active antenna amplifying arrays  

E-print Network

-fed antenna coupler. Both designs are under the same constraint that the resonant frequency and radiation patterns are least affected by the coupling parasitic. Theoretical analysis based on Maxwell's equations and simulation tools is focused on 10 GHz...MICROSTRIP ANTENNA COUPLERS AND ACTIVE ANTENNA AMPLIFYING ARRAYS A Thesis by YAO-CHOU (ANGUS) YANG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER...

Yang, Yao-Chou (Angus)

1997-01-01

226

Quantum massive conformal gravity  

E-print Network

We first find the linear approximation of the second plus fourth order derivatives massive conformal gravity action. Then we reduce the linearized action to three separated second order derivatives terms, which allows us to quantize the massive conformal gravity fields by using the usual first order canonical quantization method. Finally, using the correct conformal normalization of the massive conformal gravity states, we show that the theory is unitary.

Faria, F F

2015-01-01

227

Microsecond switchable thermal antenna  

SciTech Connect

We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO{sub 2}). This thermal source is made of a periodically patterned tunable VO{sub 2} nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO{sub 2} phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heating less, the VO{sub 2} layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.

Ben-Abdallah, Philippe, E-mail: pba@institutoptique.fr; Benisty, Henri; Besbes, Mondher [Laboratoire Charles Fabry, UMR 8501, Institut d'Optique, CNRS, Université Paris-Sud 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France)

2014-07-21

228

Microsecond switchable thermal antenna  

NASA Astrophysics Data System (ADS)

We propose a thermal antenna that can be actively switched on and off at the microsecond scale by means of a phase transition of a metal-insulator material, the vanadium dioxide (VO2). This thermal source is made of a periodically patterned tunable VO2 nanolayer, which support a surface phonon-polariton in the infrared range in their crystalline phase. Using electrodes properly registered with respect to the pattern, the VO2 phase transition can be locally triggered by ohmic heating so that the surface phonon-polariton can be diffracted by the induced grating, producing a highly directional thermal emission. Conversely, when heating less, the VO2 layers cool down below the transition temperature, the surface phonon-polariton cannot be diffracted anymore so that thermal emission is inhibited. This switchable antenna could find broad applications in the domain of active thermal coatings or in those of infrared spectroscopy and sensing.

Ben-Abdallah, Philippe; Benisty, Henri; Besbes, Mondher

2014-07-01

229

Circularly polarized microstrip antennas  

NASA Technical Reports Server (NTRS)

A simple microstrip antenna can be made to radiate EM waves of any polarization, in particular, the circular polarization (CP) without any phasing network and power divider. A simple and accurate theory for this family of antennas was developed. However, the CP bandwidth, (CPBW) the bandwidth in which the axial ratio (AR) is less than a certain specified value, is very small. Most of the experimental designs were made for a feed placed along the diagonal of the patch. It is shown that there are practically infinitely many possible designs with different feed location. The speculation that other designs might give a wider bandwidth is clarified and an effective method for broadening the bandwidth is shown.

Lo, Y. T.; Engst, B.; Lee, R. Q. H.

1985-01-01

230

Applied Conformal Field Theory  

Microsoft Academic Search

These lectures consisted of an elementary introduction to conformal field theory, with some applications to statistical mechanical systems, and fewer to string theory. Contents: 1. Conformal theories in d dimensions 2. Conformal theories in 2 dimensions 3. The central charge and the Virasoro algebra 4. Kac determinant and unitarity 5. Identication of m = 3 with the critical Ising model

Paul Ginsparg

1988-01-01

231

Superspace conformal field theory  

NASA Astrophysics Data System (ADS)

Conformal sigma models and Wess-Zumino-Witten (WZW) models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type-I supergroups, the classification of conformal sigma models and their embedding into string theory.

Quella, Thomas; Schomerus, Volker

2013-12-01

232

Irrational conformal field theory  

Microsoft Academic Search

This is a review of irrational conformal field theory, which includes rational conformal field theory as a small subspace. Central topics of the review include the Virasoro master equation, its solutions and the dynamics of irrational conformal field theory. Discussion of the dynamics includes the generalized Knizhnik-Zamolodchikov equations on the sphere, the corresponding heat-like systems on the torus and the

M. B. Halpern; E. Kiritsis; N. A. Obers; K. Clubok

1996-01-01

233

Superspace conformal field theory  

E-print Network

Conformal sigma models and WZW models on coset superspaces provide important examples of logarithmic conformal field theories. They possess many applications to problems in string and condensed matter theory. We review recent results and developments, including the general construction of WZW models on type I supergroups, the classification of conformal sigma models and their embedding into string theory.

Thomas Quella; Volker Schomerus

2014-09-23

234

Adaptive antenna systems  

Microsoft Academic Search

A system consisting of an antenna array and an adaptive processor can perform filtering in both the space and the frequency domains, thus reducing the sensitivity of the signal-receiving system to interfering directional noise sources. Variable weights of a signal processor can be automatically adjusted by a simple adaptive technique based on the least-mean-squares (LMS) algorithm. During the adaptive process

B. Widrow; P. E. Mantey; L. J. Griffiths; B. B. Goode

1967-01-01

235

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

236

Flap Antenna for Communications  

Microsoft Academic Search

In-flight satellite communication systems are finding a growing number of applications on commercial and military aircraft. In-flight satellite communication systems provide access to many valuable and real-time services such as DirecTV, XM radio, and high-speed internet services to both passengers and crew. An in-flight satellite link utilizes a high-gain antenna mounted on the aircraft, which continuously tracks a geosynchronously-orbiting satellite

Yong U. Kim

2007-01-01

237

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.

2014-09-18

238

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

239

Antenna Calibration and Measurement Equipment  

NASA Technical Reports Server (NTRS)

A document describes the Antenna Calibration & Measurement Equipment (ACME) system that will provide the Deep Space Network (DSN) with instrumentation enabling a trained RF engineer at each complex to perform antenna calibration measurements and to generate antenna calibration data. This data includes continuous-scan auto-bore-based data acquisition with all-sky data gathering in support of 4th order pointing model generation requirements. Other data includes antenna subreflector focus, system noise temperature and tipping curves, antenna efficiency, reports system linearity, and instrument calibration. The ACME system design is based on the on-the-fly (OTF) mapping technique and architecture. ACME has contributed to the improved RF performance of the DSN by approximately a factor of two. It improved the pointing performances of the DSN antennas and productivity of its personnel and calibration engineers.

Rochblatt, David J.; Cortes, Manuel Vazquez

2012-01-01

240

A Mars Riometer: Antenna Considerations  

NASA Technical Reports Server (NTRS)

This is the final report on NASA Grant NAG5-9706. This project explored riometer (relative ionospheric opacity meter) antenna designs that would be practical for a Mars surface or balloon mission. The riometer is an important radio science instrument for terrestrial aeronomy investigations. The riometer measures absorption of cosmic radio waves by the overhead ionosphere. Studies have shown the instrument should work well on Mars, which has an appreciable daytime ionosphere. There has been concern that the required radio receiver antenna (with possibly a 10 meter scale size) would be too large or too difficult to deploy on Mars. This study addresses those concerns and presents several antenna designs and deployment options. It is found that a Mars balloon would provide an excellent platform for the riometer antenna. The antenna can be incorporated into the envelope design, allowing self-deployment of the antenna as the balloon inflates.

Fry, Craig D.

2001-01-01

241

Antenna structure with distributed strip  

DOEpatents

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

242

Antenna structure with distributed strip  

DOEpatents

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

243

The ACTS multibeam antenna  

NASA Technical Reports Server (NTRS)

The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 introduces several new technologies including a multibeam antenna (MBA) operating at Ka-band. The satellite is introduced briefly, and then the MBA, consisting of electrically similar 30 GHz received and 20 GHz transmit offset Cassegrain systems utilizing orthogonal linear polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 deg beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz high mobility electron transmitter (HEMT) low-noise amplifier and a 20 GHz TWT power amplifier.

Regier, Frank A.

1992-01-01

244

Modular antenna design study  

NASA Technical Reports Server (NTRS)

The mechanical design of a modular antenna concept was developed sufficiently to allow manufacture of a working demonstration model of a module, to predict mass properties, and to make performance estimates for antenna reflectors composed of these modules. The primary features of this concept are: (1) each module is an autonomous structural element which can be attached to adjacent modules through a three point connection; (2) the upper surface is a folding hexagonal truss plate mechanism which serves as the supporting structure for a reflective surface; and (3) the entire truss and surface can be folded into a cylindrical envelope in which all truss elements are essentially parallel. The kinematic studies and engineering demonstration model fully verified the deployment kinematics, stowing philosophy, and deployment sequencing for large antenna modules. It was established that such modules can be stowed in packages as small as 25 cm in diameter, using 1.27 cm diameter structural tubes. The development activity indicates that this deployable modular approach towards building large structures in space will support erection of 450 m apertures for operation up to 3 GHz with a single space shuttle flight.

Ribble, J. W.

1981-01-01

245

SPS antenna element evaluation  

NASA Technical Reports Server (NTRS)

The SPS transmitting array requires an architecture which will provide a low weight, high efficiency and high structural rigidity. Waveguide slot arrays constitute the most desirable option. Consequently, such an array was chosen for the SPS. Waveguide slot arrays offer high efficiency, uniform illumination, and are fairly lightweight. Bandwidths of such arrays are narrow, typically 1/2-2%. Although this does not directly impact the SPS, which transmits power at a single frequency of 2.45 GHz, the narrow bandwidth does constrain the thermal and mechanical tolerances of the antenna. The purpose of this program is to better define the electronic aspects of an SPS specific waveguide slot array. The specific aims of the program are as follows: (1) To build a full-scale half-module, 10 stick, array, the design parameters for which are to be determined analytical considerations tempered by experimental data on a single slotted radiating stick, (2) To experimentally evaluate the completed array with respect to antenna pattern, impedance and return loss; and (3) To measure swept transmission amplitude and phase to provide a data base for design of a receiving antenna.

Lunden, C. D.; Lund, W. W.; Nalos, E. J.

1980-01-01

246

Design of Microstrip Antennas with Composite Laminates Considering Their Structural Rigidity  

Microsoft Academic Search

Two types of conformal load-bearing antenna structures (CLAS) were designed with microwave composite laminates and Nomex honeycomb cores to secure both the structural rigidity and a good electrical performance. One was a 4 × 8 array for the synthetic-aperture radar (SAR) system and the other was a 5 × 2 array for the wireless local-area network (LAN) system. The design

J. H. Jeon; C. S. You; C. K. Kim; W. Hwang; H. C. Park; W. S. Park

2002-01-01

247

Deployable antenna phase A study  

NASA Technical Reports Server (NTRS)

Applications for large deployable antennas were re-examined, flight demonstration objectives were defined, the flight article (antenna) was preliminarily designed, and the flight program and ground development program, including the support equipment, were defined for a proposed space transportation system flight experiment to demonstrate a large (50 to 200 meter) deployable antenna system. Tasks described include: (1) performance requirements analysis; (2) system design and definition; (3) orbital operations analysis; and (4) programmatic analysis.

Schultz, J.; Bernstein, J.; Fischer, G.; Jacobson, G.; Kadar, I.; Marshall, R.; Pflugel, G.; Valentine, J.

1979-01-01

248

Compact antennas for UWB applications  

Microsoft Academic Search

This paper reports on an investigation of spherical, disc, and half-disc antennas in the frequency and time domains with the objective of developing small planar versions of the antennas. These antennas have an omni-directional impulse response in azimuth and a pulse duration of 0.5 - 0.65 nanoseconds. In addition, the measured data show a reasonable peak received signal in a

Taeyoung Yang; Seong-Youp Suh; Randall Nealy; William A. Davis; Warren L. Stutzman

2003-01-01

249

Compact antennas for UWB applications  

Microsoft Academic Search

A report on an investigation of spherical, disc, and half-disc antennas in the frequency and time domains with the objective of developing small planar versions of the antennas. These antennas have an omni-directional impulse response in azimuth and pulse duration of 0.5-0.65 nanoseconds. In addition, the measured data show a reasonable peak received signal in a pulse communication link using

Taeyoung Yang; Seong-Youp Suh; Randall Nealy; William A. Davis; Warren L. Stutzman

2004-01-01

250

Antenna Squint and Guidance Errors  

Microsoft Academic Search

Missile-guidance errors caused by antenna and electronic faults are discussed. After describing a typical closed-loop angular sensing system using a gyrostabilized microwave antenna, the peculiarities of a crossed-dipole feed are listed. With imperfect electronic processing in the closed loop, the feed aberrations generate false steering signals. Two kinds of antenna squint are then dealt with, one sensitive to polarization and

Norman F. de Groot

1963-01-01

251

Analyzing Large Reflector Antenna Structures  

NASA Technical Reports Server (NTRS)

Iterative Design of Antenna Structures (IDEAS) computer program performs finite-element analysis and optimization of design, with special features for analysis and design of microwave antennas and associated structural components. Primary feature to perform root-mean-square-best-fitting path-length-error and boresight-pointing-error analyses for Cassegrain microwave antenna structure loaded by gravity, wind, or other environmental effects. Flexible and easy to use. Written in ATHENA FORTRAN and ASSEMBLER.

Levy, Roy; Strain, Douglas M.

1991-01-01

252

Analysis of rectangular microstrip antennas  

NASA Technical Reports Server (NTRS)

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 the unknown patch current. Using the present formulation, the radiation pattern, the resonant frequency, and the bandwidth of a rectangular microstrip antenna are computed. Design data for a rectangular microstrip antenna are also presented.

Bailey, M. C.; Deshpande, M. D.

1984-01-01

253

47 CFR 74.1237 - Antenna location.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna location. 74.1237 Section 74...Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant...the primary station. The transmitting antenna should be placed above growing...

2013-10-01

254

47 CFR 95.1213 - Antennas.  

Code of Federal Regulations, 2010 CFR

...Telecommunication 5 2010-10-01 2010-10-01 false Antennas. 95.1213 Section 95.1213 Telecommunication...Radiocommunication Service (MedRadio) § 95.1213 Antennas. No antenna for a MedRadio transmitter shall be...

2010-10-01

255

47 CFR 73.1680 - Emergency antennas.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Emergency antennas. 73.1680 Section 73.1680 Telecommunication...Broadcast Stations § 73.1680 Emergency antennas. (a) An emergency antenna is one that is erected for temporary use...

2011-10-01

256

47 CFR 80.923 - Antenna system.  

Code of Federal Regulations, 2011 CFR

... 5 2011-10-01 2011-10-01 false Antenna system. 80.923 Section 80.923 Telecommunication...Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the...

2011-10-01

257

47 CFR 73.69 - Antenna monitors.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna monitors. 73.69 Section 73.69...SERVICES AM Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the...

2010-10-01

258

47 CFR 101.517 - Antennas.  

Code of Federal Regulations, 2011 CFR

...5 2011-10-01 2011-10-01 false Antennas. 101.517 Section 101.517 Telecommunication...Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional,...

2011-10-01

259

47 CFR 73.1675 - Auxiliary antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Auxiliary antennas. 73.1675 Section 73.1675 Telecommunication...Broadcast Stations § 73.1675 Auxiliary antennas. (a)(1) An auxiliary antenna is one that is permanently installed and...

2014-10-01

260

47 CFR 73.1680 - Emergency antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Emergency antennas. 73.1680 Section 73.1680 Telecommunication...Broadcast Stations § 73.1680 Emergency antennas. (a) An emergency antenna is one that is erected for temporary use...

2013-10-01

261

47 CFR 74.1237 - Antenna location.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna location. 74.1237 Section 74...Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant...the primary station. The transmitting antenna should be placed above growing...

2012-10-01

262

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Spare antenna. 80.866 Section 80.866 Telecommunication...Vessels Not Subject to Subpart W § 80.866 Spare antenna. A spare transmitting antenna completely assembled for immediate erection...

2012-10-01

263

47 CFR 101.117 - Antenna polarization.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna polarization. 101.117 Section 101... Technical Standards § 101.117 Antenna polarization. Except as...vertical and/or horizontal polarization for antennas located within 20 kilometers of the...

2013-10-01

264

47 CFR 73.1680 - Emergency antennas.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Emergency antennas. 73.1680 Section 73.1680 Telecommunication...Broadcast Stations § 73.1680 Emergency antennas. (a) An emergency antenna is one that is erected for temporary use...

2012-10-01

265

47 CFR 73.816 - Antennas.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antennas. 73.816 Section 73.816 Telecommunication...Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only...

2010-10-01

266

47 CFR 101.517 - Antennas.  

Code of Federal Regulations, 2012 CFR

...5 2012-10-01 2012-10-01 false Antennas. 101.517 Section 101.517 Telecommunication...Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional,...

2012-10-01

267

47 CFR 73.1675 - Auxiliary antennas.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Auxiliary antennas. 73.1675 Section 73.1675 Telecommunication...Broadcast Stations § 73.1675 Auxiliary antennas. (a)(1) An auxiliary antenna is one that is permanently installed and...

2012-10-01

268

47 CFR 73.1680 - Emergency antennas.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Emergency antennas. 73.1680 Section 73.1680 Telecommunication...Broadcast Stations § 73.1680 Emergency antennas. (a) An emergency antenna is one that is erected for temporary use...

2010-10-01

269

47 CFR 101.117 - Antenna polarization.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna polarization. 101.117 Section 101... Technical Standards § 101.117 Antenna polarization. Except as...vertical and/or horizontal polarization for antennas located within 20 kilometers of the...

2012-10-01

270

47 CFR 80.923 - Antenna system.  

Code of Federal Regulations, 2013 CFR

... 5 2013-10-01 2013-10-01 false Antenna system. 80.923 Section 80.923 Telecommunication...Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the...

2013-10-01

271

47 CFR 73.1680 - Emergency antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Emergency antennas. 73.1680 Section 73.1680 Telecommunication...Broadcast Stations § 73.1680 Emergency antennas. (a) An emergency antenna is one that is erected for temporary use...

2014-10-01

272

47 CFR 101.117 - Antenna polarization.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna polarization. 101.117 Section 101... Technical Standards § 101.117 Antenna polarization. Except as...vertical and/or horizontal polarization for antennas located within 20 kilometers of the...

2010-10-01

273

47 CFR 73.816 - Antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antennas. 73.816 Section 73.816 Telecommunication...Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only...

2013-10-01

274

47 CFR 73.816 - Antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antennas. 73.816 Section 73.816 Telecommunication...Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only...

2014-10-01

275

47 CFR 95.1213 - Antennas.  

Code of Federal Regulations, 2011 CFR

...Telecommunication 5 2011-10-01 2011-10-01 false Antennas. 95.1213 Section 95.1213 Telecommunication...Radiocommunication Service (MedRadio) § 95.1213 Antennas. No antenna for a MedRadio transmitter shall be...

2011-10-01

276

47 CFR 101.517 - Antennas.  

Code of Federal Regulations, 2013 CFR

...5 2013-10-01 2013-10-01 false Antennas. 101.517 Section 101.517 Telecommunication...Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional,...

2013-10-01

277

47 CFR 15.203 - Antenna requirement.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna requirement. 15.203 Section 15... Intentional Radiators § 15.203 Antenna requirement. An intentional radiator shall be designed to ensure that no antenna other than that furnished by the...

2013-10-01

278

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Spare antenna. 80.866 Section 80.866 Telecommunication...Vessels Not Subject to Subpart W § 80.866 Spare antenna. A spare transmitting antenna completely assembled for immediate erection...

2011-10-01

279

47 CFR 73.69 - Antenna monitors.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna monitors. 73.69 Section 73.69...SERVICES AM Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the...

2011-10-01

280

47 CFR 74.1237 - Antenna location.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna location. 74.1237 Section 74...Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant...the primary station. The transmitting antenna should be placed above growing...

2014-10-01

281

47 CFR 101.517 - Antennas.  

Code of Federal Regulations, 2010 CFR

...5 2010-10-01 2010-10-01 false Antennas. 101.517 Section 101.517 Telecommunication...Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional,...

2010-10-01

282

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Spare antenna. 80.866 Section 80.866 Telecommunication...Vessels Not Subject to Subpart W § 80.866 Spare antenna. A spare transmitting antenna completely assembled for immediate erection...

2013-10-01

283

47 CFR 74.1237 - Antenna location.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna location. 74.1237 Section 74...Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant...the primary station. The transmitting antenna should be placed above growing...

2011-10-01

284

47 CFR 73.1675 - Auxiliary antennas.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Auxiliary antennas. 73.1675 Section 73.1675 Telecommunication...Broadcast Stations § 73.1675 Auxiliary antennas. (a)(1) An auxiliary antenna is one that is permanently installed and...

2011-10-01

285

47 CFR 74.1237 - Antenna location.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna location. 74.1237 Section 74...Broadcast Booster Stations § 74.1237 Antenna location. (a) An applicant...the primary station. The transmitting antenna should be placed above growing...

2010-10-01

286

47 CFR 15.203 - Antenna requirement.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna requirement. 15.203 Section 15... Intentional Radiators § 15.203 Antenna requirement. An intentional radiator shall be designed to ensure that no antenna other than that furnished by the...

2014-10-01

287

47 CFR 73.69 - Antenna monitors.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna monitors. 73.69 Section 73.69...SERVICES AM Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the...

2013-10-01

288

47 CFR 73.69 - Antenna monitors.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna monitors. 73.69 Section 73.69...SERVICES AM Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the...

2014-10-01

289

47 CFR 73.1675 - Auxiliary antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Auxiliary antennas. 73.1675 Section 73.1675 Telecommunication...Broadcast Stations § 73.1675 Auxiliary antennas. (a)(1) An auxiliary antenna is one that is permanently installed and...

2013-10-01

290

47 CFR 73.816 - Antennas.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antennas. 73.816 Section 73.816 Telecommunication...Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only...

2012-10-01

291

47 CFR 80.923 - Antenna system.  

Code of Federal Regulations, 2012 CFR

... 5 2012-10-01 2012-10-01 false Antenna system. 80.923 Section 80.923 Telecommunication...Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the...

2012-10-01

292

47 CFR 73.816 - Antennas.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antennas. 73.816 Section 73.816 Telecommunication...Broadcast Stations (LPFM) § 73.816 Antennas. (a) Permittees and licensees may employ nondirectional antennas with horizontal only...

2011-10-01

293

47 CFR 80.923 - Antenna system.  

Code of Federal Regulations, 2010 CFR

... 5 2010-10-01 2010-10-01 false Antenna system. 80.923 Section 80.923 Telecommunication...Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the...

2010-10-01

294

47 CFR 73.69 - Antenna monitors.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna monitors. 73.69 Section 73.69...SERVICES AM Broadcast Stations § 73.69 Antenna monitors. (a) Each station using a directional antenna must have in operation at the...

2012-10-01

295

Large Space Antenna Systems Technology, 1984  

NASA Technical Reports Server (NTRS)

Mission applications for large space antenna systems; large space antenna structural systems; materials and structures technology; structural dynamics and control technology, electromagnetics technology, large space antenna systems and the Space Station; and flight test and evaluation were examined.

Boyer, W. J. (compiler)

1985-01-01

296

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2010 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...

2010-10-01

297

47 CFR 80.923 - Antenna system.  

Code of Federal Regulations, 2014 CFR

... 5 2014-10-01 2014-10-01 false Antenna system. 80.923 Section 80.923 Telecommunication...Installations for Small Passenger Boats § 80.923 Antenna system. An antenna must be provided in accordance with the...

2014-10-01

298

47 CFR 101.517 - Antennas.  

Code of Federal Regulations, 2014 CFR

...5 2014-10-01 2014-10-01 false Antennas. 101.517 Section 101.517 Telecommunication...Digital Electronic Message Service § 101.517 Antennas. (a) Transmitting antennas may be omnidirectional or directional,...

2014-10-01

299

47 CFR 80.866 - Spare antenna.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Spare antenna. 80.866 Section 80.866 Telecommunication...Vessels Not Subject to Subpart W § 80.866 Spare antenna. A spare transmitting antenna completely assembled for immediate erection...

2014-10-01

300

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2012 CFR

...antennas for operations such as space diversity) meeting the appropriate performance...antennas used at an electric power facility plant area will be excluded from the...antennas for operations such as space diversity) meeting the...

2012-10-01

301

Optical resonant Archimedean spiral antennas  

NASA Astrophysics Data System (ADS)

We investigated the field enhancement properties of optical resonant Archimedean spiral antennas by using a finite difference time domain method. Due to the spiral structure, the antennas show a circular dichroism in the electric field enhancement, especially for a large turning angle. A large magnetic field enhancement is also obtained with a confinement in the nanometer size. When the turning angle equals ? for a linearly polarized incident beam, the polarization of the enhanced field in the spiral antenna can be perpendicular to the incident polarization with a similar enhancement factor to the optical resonant dipole antennas.

Wen, Hanqing; Yang, Jing; Zhang, Weiwei; Zhang, Jiasen

2011-01-01

302

Metamaterial-based "sabre" antenna  

NASA Astrophysics Data System (ADS)

The "sabre" antenna is an array of two monopole elements, vertically polarized with omnidirectional radiation patterns, and placed on either side of a composite material on the tail of an airplane. As an in-phase reflector plane, the antenna uses a compact dual-layer high-impedance surface (DL-HIS) with offset mushroom-like Sivenpiper square shape unit cells. This topology allows one to control both operational frequency and bandgap width, while reducing the total height of the antenna to under ?0/36. The designed antenna structure has a wide bandwidth higher than 24% around 1.4 GHz. The measurements and numerical simulations agree very well.

Hafdallah Ouslimani, Habiba; Yuan, Tangjie; Kanane, Houcine; Priou, Alain; Collignon, Gérard; Lacotte, Guillaume

2014-05-01

303

Antenna system for MSAT mission  

NASA Technical Reports Server (NTRS)

Spar has evaluated and compared several antenna concepts for the North American Mobile Satellite. The paper describes some of the requirements and design considerations for the antennas and demonstrates the performance of antenna concepts that can meet them. Multiple beam reflector antennas are found to give best performance and much of the design effort has gone into the design of the primary feed radiators and beam forming networks to achieve efficient beams with good overlap and flexibility. Helices and cup dipole radiators have been breadboarded as feed element candidates and meausured results are presented. The studies and breadboard activities have made it possible to proceed with a flight program.

Karlsson, Ingmar; Patenaude, Yves; Stipelman, Leora

1988-01-01

304

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

305

Optical antenna gain. 2: receiving antennas.  

PubMed

Expressions are derived for the gain of a centrally obscured, circular optical antenna when used as the collecting and focusing optics in a laser receiver which include losses due to (1) blockage of the incoming light by the central obscuration, (2) the spillover of energy at the detector, and (3) the effect of local oscillator distribution in the case of heterodyne or homodyne detection. Numerical results are presented for direct detection and for three types of local oscillator distributions (uniform, Gaussian, and matched) in the case of heterodyne or homodyne detection. The results are presented in several graphs that allow the rapid evaluation of receiver gain for an arbitrary set of telescope and detector parameters. It is found that, for uniform illumination by the LO, the optimum SNR is obtained when the detector radius is approximately 0.74 times the Airy disk radius. The use of an optimized Gaussian (spot size = 0.46 times the Airy disk radius) improves the receiver gain by less than 1 dB. Theuse results are insensitive to the size of the central obscuration. PMID:20134695

Degnan, J J; Klein, B J

1974-10-01

306

Millimeter and submillimeter wave antenna structure  

NASA Technical Reports Server (NTRS)

An integrated circuit antenna structure for transmitting or receiving millimeter and/or submillimeter wave radiation having an antenna relatively unimpaired by the antenna mounting arrangment is disclosed herein. The antenna structure of the present invention includes a horn disposed on a substrate for focusing electromagnetic energy with respect to an antenna. The antenna is suspended relative to the horn to receive or transmit the electromagnetic energy focused thereby.

Rebiez, Gabriel M. (Inventor); Rutledge, David B. (Inventor)

1989-01-01

307

Conformal and near-conformal field theories  

NASA Astrophysics Data System (ADS)

Non-Abelian gauge fermion systems could be chirally broken and confining or conformal, depending on the number of fermions and their representation. Models near the conformal boundary are important as they could be relevant in describing physics beyond the Standard Model. These models are strongly coupled and require non-perturbative investigations. Lattice techniques that were developed for QCD studies can be used to simulate these systems but there is growing evidence that new observables, new approaches are needed to study the properties of conformal or near conformal models. In this talk I will briefly summarize the most promising models and describe some standard and some promising new methods to study their properties.

Hasenfratz, Anna

2013-03-01

308

View of Antenna #2 (foreground), and Antenna #1 surface doors. ...  

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

View of Antenna #2 (foreground), and Antenna #1 surface doors. Orientation Target #1 in background. Image looking northwest - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

309

View of Antenna #1 (foreground), and Antenna #2 surface doors. ...  

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

View of Antenna #1 (foreground), and Antenna #2 surface doors. Orientation Target #2 in background. Image looking northeast - Titan One Missile Complex 2A, .3 miles west of 129 Road and 1.5 miles north of County Line Road, Aurora, Adams County, CO

310

Antenna research and development at Ericsson  

NASA Astrophysics Data System (ADS)

This article gives an overview of the antenna research and development activities at Ericsson Radar Electronics AB, in Molndal, Sweden. The article covers different types of microwave antennas, such as twist-Cassegrain antennas, shaped-reflector antennas, microstrip antennas, dichroic surfaces, slotted-waveguide-array antennas, omnidirectional antennas, and electronically-steered-array antennas. Measurement methods, such as near-field and diagnostic techniques, are also discussed. The applications are for radar and microwave communication systems, for use in ground, naval, airborne, and space environments.

Dahlsjo, Olof

1992-04-01

311

A Novel Class of Reconfigurable Spherical Fermat Spiral Multi-port Antennas  

NASA Astrophysics Data System (ADS)

Reconfigurability in antenna systems is a desired characteristic that has attracted attention in the past years. In this work, a novel class of spherical Fermat spiral multi-port antennas for next-generation wireless communications and radar applications is presented. The device modelling is carried out by using a computationally enhanced locally conformal finite-difference time-domain full-wave procedure. In this way, the circuital characteristics and radiation properties of the antennas are investigated accurately. The structure reconfigurability, in terms of frequency of operation and radiation efficiency, is technically performed by a suitable solid-state tuning circuitry adopted to properly change the feeding/loading conditions at the input ports of the antenna.

Caratelli, D.; Yarovoy, A.; Haider, N.

312

Optical antenna enhanced spontaneous emission.  

PubMed

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ?200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ?115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ?2,500× spontaneous emission speedup at d ? 10 nm, proportional to 1/d(2). Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = q?|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

2015-02-10

313

Theory of plasma antenna windowing  

Microsoft Academic Search

Summary form only given. This paper sets forth a detailed numerical analysis of the performance of a reconfigurable antenna comprised of a linear omni-directional antenna surrounded by a cylindrical shell of conducting plasma. The plasma shield consists of a series of tubes containing a gas, which upon electrification, forms a plasma (in practice fluorescent light bulbs are used). The plasma

T. Anderson; I. Alexeff

2004-01-01

314

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

315

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

316

Astronaut space suit communication antenna  

NASA Technical Reports Server (NTRS)

Astronaut space suit communication antenna consists of a spring steel monopole in a blade-type configuration. This antenna is mounted in a copper cup filled with a potting compound that is recessed in the center to facilitate bending the blade flat for stowing when not in use.

Lindsey, J. F., III; Nason, G. H.

1968-01-01

317

Optical antenna enhanced spontaneous emission  

PubMed Central

Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ?200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ?115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ?2,500× spontaneous emission speedup at d ? 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = q?|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C.

2015-01-01

318

Antenna\\/transmitter control unit  

Microsoft Academic Search

The primary function of the antenna control unit is control of the Command and Data Acquisition Station (CDAS) 18 m phi antenna driver, and part of its function is performed by a central monitoring and control central processing unit (CPU) board. These units are connected to the station control and monitor unit (Mini computer system) via process I\\/O unit. Each

Seiji Kawabata; Masahiro Sasaki

1989-01-01

319

Broadband logarithmically periodic antenna structures  

Microsoft Academic Search

Antenna structures for which the input impedance and radiation patterns vary periodically with the logarithm of the frequency are described. For a particular class of these structures the variation of the electrical characteristics over a period is negligible, the result being an antenna for which the impedance and patterns are essentially independent of frequency over bandwidths greater than ten to

R. H. DuHamel; D. E. Isbell

1957-01-01

320

Collapsible corrugated horn antenna  

NASA Technical Reports Server (NTRS)

A horn antenna that is readily collapsible while not in use is described. A number of different sized annular metal rings are arranged in a sequence such that each ring is larger than the one that precedes it in the sequence. A number of thin flexible electrically conductive members attach successive metal rings together physically and connect them together electrically. Each flexible conductive member is attached to make electrical contact between the outside surface of a metal ring and the inside surface of an adjacent metal ring in the sequence.

Barthlome, D. E. (inventor)

1978-01-01

321

Small high directivity ferrite antennas  

NASA Astrophysics Data System (ADS)

A centimeter-wavelength antenna of millimetric dimensions, which uses the intrinsic angular sensitivity of ferrites, is described, with an emphasis on the modification of the material's permeability. The construction of both the ferrite film lens antenna and the ferrite film cassegrain antenna are detailed; both can be devised in a number of configurations for appropriate beam positioning and rf filtering. The antenna design, discussed primarily in the context of smart missiles, electronic warfare, and satellite systems, presents the possibility of magnetically switching between the transmit and receive modes within the antenna structure itself. Finally, it is noted that for a simple 2-dipole array the angular resolution can be two orders of magnitude higher than with the conventional techniques.

Wright, T. M. B.

322

Optical antennas as nanoscale resonators  

E-print Network

Recent progress in nanotechnology has enabled us to fabricate subwavelength architectures that function as antennas for improving the exchange of optical energy with nanoscale matter. We describe the main features of optical antennas for enhancing quantum emitters and review designs that increase the spontaneous emission rate by orders of magnitude from the ultraviolet up to the near-infrared spectral range. To further explore how optical antennas may lead to unprecedented regimes of light-matter interaction, we draw a relationship between metal nanoparticles, radio-wave antennas and optical resonators. Our analysis points out how optical antennas may function as nanoscale resonators and how these may offer unique opportunities with respect to state-of-the-art microcavities.

Mario Agio

2011-11-05

323

Transcatheter Microwave Antenna  

NASA Technical Reports Server (NTRS)

A method, simulation, and apparatus are provided that are highly suitable for treatment of benign prostatic hyperplasia (BPH). A catheter is disclosed that includes a small diameter disk loaded monopole antenna surrounded by fusion material having a high heat of fusion and a melting point preferably at or near body temperature. Microwaves from the antenna heat prostatic tissue to promote necrosing of the prostatic tissue that relieves the pressure of the prostatic tissue against the urethra as the body reabsorbs the necrosed or dead tissue. The fusion material keeps the urethra cool by means of the heat of fusion of the fusion material. This prevents damage to the urethra while the prostatic tissue is necrosed. A computer simulation is provided that can be used to predict the resulting temperature profile produced in the prostatic tissue. By changing the various control features of the catheter and method of applying microwave energy a temperature profile can be predicted and produced that is similar to the temperature profile desired for the particular patient.

Arndt, Dickey G. (Inventor); Carl, James R. (Inventor); Ngo, Phong (Inventor); Raffoul, George W. (Inventor)

2001-01-01

324

Adaptive multibeam antenna array  

NASA Astrophysics Data System (ADS)

An adaptive multibeam antenna array is considered which will enhance the advantages of a plain one. By providing simultaneous reception of signals from different directions and their sequential processing. The optimization of the array control for maximum interference suppression in the radiation pattern is emphasized. The optimum control is sought with respect to the signal-to-interference power ratio as a genaralized criterion. Sampled useful signals and transmission coefficients are found to be complex-conjugate quantities, assuming compatible formation of beams, so that synphasal equiamplitude addition of signals from all array element is attainable by unique settings of the weight factors. Calculations are simplified by letting the useful signal power in the 1-th beam be approximately equal to the k-th weight factor, before optimizing the weight vector for maximum signal-to-interference ratio. A narrowband interference described by power P and vector V of signal distribution over the array is considered as an example, to demonstrate the algorithm of synthesis. The algorithm, using the Butler matrix, was executed experimentally on a computer for a linear equidistant antenna array of 32 elements with compatible formation of beams.

Novikov, V. I.

1984-01-01

325

Galilean conformal electrodynamics  

NASA Astrophysics Data System (ADS)

Maxwell's Electrodynamics admits two distinct Galilean limits called the Electric and Magnetic limits. We show that the equations of motion in both these limits are invariant under the Galilean Conformal Algebra in D = 4, thereby exhibiting non-relativistic conformal symmetries. Remarkably, the symmetries are infinite dimensional and thus Galilean Electrodynamics give us the first example of an infinitely extended Galilean Conformal Field Theory in D > 2. We examine details of the theory by looking at purely non-relativistic conformal methods and also use input from the limit of the relativistic theory.

Bagchi, Arjun; Basu, Rudranil; Mehra, Aditya

2014-11-01

326

Galilean Conformal Electrodynamics  

E-print Network

Maxwell's Electrodynamics admits two distinct Galilean limits called the Electric and Magnetic limits. We show that the equations of motion in both these limits are invariant under the Galilean Conformal Algebra in D=4, thereby exhibiting non-relativistic conformal symmetries. Remarkably, the symmetries are infinite dimensional and thus Galilean Electrodynamics give us the first example of an infinitely extended Galilean Conformal Field Theory in D>2. We examine details of the theory by looking at purely non-relativistic conformal methods and also use input from the limit of the relativistic theory.

Bagchi, Arjun; Mehra, Aditya

2014-01-01

327

Antennas Designed for Advanced Communications for Air Traffic Management (AC/ATM) Project  

NASA Technical Reports Server (NTRS)

The goal of the Advanced Communications for Air Traffic Management (AC/ATM) Project at the NASA Glenn Research Center at Lewis Field is to enable a communications infrastructure that provides the capacity, efficiency, and flexibility necessary to realize a mature free-flight environment. The technical thrust of the AC/ATM Project is targeted at the design, development, integration, test, and demonstration of enabling technologies for global broadband aeronautical communications. Since Ku-band facilities and equipment are readily available, one of the near-term demonstrations involves a link through a Kuband communications satellite. Two conformally mounted antennas will support the initial AC/ATM communications links. Both of these are steered electronically through monolithic microwave integrated circuit (MMIC) amplifiers and phase shifters. This link will be asymmetrical with the downlink to the aircraft (mobile vehicle) at a throughput rate of greater than 1.5 megabits per second (Mbps), whereas the throughput rate of the uplink from the aircraft will be greater than 100 kilobits per second (kbps). The data on the downlink can be narrow-band, wide-band, or a combination of both, depending on the requirements of the experiment. The AC/ATM project is purchasing a phased-array Ku-band transmitting antenna for the uplink from the test vehicle. Many Ku-band receiving antennas have been built, and one will be borrowed for a short time to perform the initial experiments at the NASA Glenn Research Center at Lewis Field. The Ku-band transmitting antenna is a 254-element MMIC phased-array antenna being built by Boeing Phantom Works. Each element can radiate 100 mW. The antenna is approximately 43-cm high by 24-cm wide by 3.3-cm thick. It can be steered beyond 60 from broadside. The beamwidth varies from 6 at broadside to 12 degrees at 60 degrees, which is typical of phased-array antennas. When the antenna is steered to 60 degrees, the beamwidth will illuminate approximately five satellites on the orbital arc. Spread spectrum techniques will be employed to keep the power impinging on the adjacent satellites below their noise floor so that no interference results. This antenna is power limited. If the antenna elements (currently 254) are increased by a factor of 4 (1024) or 16 (4096), the gain will increase and the beamwidth will decrease in proportion. For the latter two antenna sizes, the power must be "backed off" to prevent interference with the neighboring satellites. The receiving antenna, which is approximately 90-cm high, 60-cm wide, and 3.5-cm thick, is composed of 1500 phased-array elements. The system phased-array controller can control both a 1500-element receiving antenna and a 500-element transmitting antenna. For ground testing, this controller will allow manual beam pointing and polarization alignment. For normal operation, the system can be connected to the receiving antenna and the navigation system for real-time autonomous track operation. This will be accomplished by first pointing both antennas at the satellite using information from the aircraft data bus. Then, the system phased-array controller will electronically adjust the antenna pointing of the receiving antenna to find the peak signal. After the peak signal has been found, the beam of the transmitting antenna will be pointed to the same steering angles as the receiving antenna. For initial ground testing without an aircraft, the ARINC 429 data bus (ARINC Inc., Annapolis, Maryland) will be simulated by a gyro system purchased for the follow-on to the Monolithic Microwave Integrated Circuit (MMIC) Arrays for Satellite Communication on the Move (MASCOM) Project. MASCOM utilized the Advanced Communications Technology Satellite (ACTS) with a pair of Ka-band experimental phased-array antennas.

Zakrajsek, Robert J.

2000-01-01

328

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 3, 2004 45 A Wideband Monopole Antenna for  

E-print Network

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 3, 2004 45 A Wideband Monopole Antenna for PCS--A triple-band stubby antenna fed by a coaxial probe and tuning technique are proposed for operating at PCS, IMT-2000, and Bluetooth bands. The proposed antenna shielded by the antenna cover consists of the two

Park, Seong-Ook

329

A 6-ridge horn antenna for spherical near-field antenna measurements  

Microsoft Academic Search

This paper introduces an idea of a 6-ridge horn antenna for spherical near-field antenna measurements. It is shown that, as opposed to a quad-ridge horn antenna, the 6-ridge horn antenna gives, in theory, a possibility to achieve quasi-first-order characteristics for the antenna over a substantially wide frequency range provided a proper feeding can be realized.

Tommi Laitinen; Janne Ilvonen

2009-01-01

330

Forthcoming Publications: Science, PRL Optical Antennas  

E-print Network

Forthcoming Publications: Science, PRL Optical Antennas D.W. Pohl This work presented here.nano-optics.ch Schweizerischer Nationalfonds FNSNF #12;My definition of an antenna....: #12;...adopts that of radio wave technology. antenna arms feed gap antenna cable connecting to load reflectors directors radiation lobes #12

331

Wireless@Virginia Tech Antennas and Propagation  

E-print Network

Wireless@Virginia Tech SWIM Antennas and Propagation Need for Research The success of any wireless communications device is integrally tied to the antennas used to transmit the signal. The antenna design must with a myriad of environmental elements, such as multipath, path loss, reflection, and scattering makes antenna

Beex, A. A. "Louis"

332

Helix Antennas Dr. Sandra Cruz-Pol  

E-print Network

, circular or linear (vertical), depending on which receiver is being used. Narrow Band Antennas Circularly11 Helix Antennas Dr. Sandra Cruz-Pol INEL 5305 UPRM Antenna Theory and Design Helix antenna Ioe- jkr 4r sin (lazo) (i) Si |E| = |E| tenemos polarización circular. (ii) En general la polarización

Cruz-Pol, Sandra L.

333

NRL Low-Frequency Antenna Development  

E-print Network

NRL Low-Frequency Antenna Development Brian Hicks W. Erickson, K. Stewart #12;NRL Low Frequency Antenna Development Our goal has been to research and develop wide- bandwidth low-frequency antennas.g. Galactic drift scans, solar bursts, and other strong sources) #12;NRL Low Frequency Antenna Development

Ellingson, Steven W.

334

PIFAS antennas design for mobile communications  

Microsoft Academic Search

To answer to the increasing demand of antennas for portable terminals, many works were carried out these last years starting from the shorted-circuit quarter wave antenna more commonly called PIFA (Planar Inverted-F Antenna). These antennas have for principal advantages, their compactness and their weak manufacturing costs, in addition to their significant performances. In this article, we present new geometries for

Y. Belhadef; N. Boukli Hacene

2011-01-01

335

Antenna and system design with Ansoft  

Microsoft Academic Search

Summary form only given. This short course will provide a broad understanding of Ansoft's software products for the design, analysis and optimization of antennas, phased array antennas and antenna systems. No prior use of Ansoft's products is required. The course will begin with an overview of HFSS™ for the design of arbitrary 3D antenna elements including model entry and efficient

J. Silvestro; J. DeLap; T. Donisi

2003-01-01

336

Intravascular extended sensitivity (IVES) MRI antennas  

Microsoft Academic Search

The design and application of an intravascular extended sensi- tivity (IVES) MRI antenna is described. The device is a loopless antenna design that incorporates both an insulating, dielectric coating and a winding of the antenna whip into a helical shape. Because this antenna produces a broad region of high SNR and also allows for imaging near the tip of the

Robert C. Susil; Christopher J. Yeung; Ergin Atalar

2003-01-01

337

Wire-antenna designs using genetic algorithms  

Microsoft Academic Search

There is a large class of electromagnetic radiators designated as wire antennas. As a rule, an inductive process is used to design these antennas. Either an integral equation is formulated or a simulator is used that gives the current distributions on the wires of the antenna, from which the electromagnetic properties of the antenna can then be determined. Once the

Edward E. Altshuler; Derek S. Linden

1997-01-01

338

Antennas for spacecraft synthetic aperture radars  

NASA Technical Reports Server (NTRS)

Future SAR missions will require light weight, multifrequency, multipolarization spacecraft antennas. NASA has conducted an investigation of possible antenna technologies, and has identified two promising technologies: interleaved open-ended waveguide antennas constructed from metallized graphite epoxy and distributed microstrip antennas. The investigation and candidate technologies are described in this paper.

Davidson, S. E.

1986-01-01

339

Space Exploration Initiative multibeam antenna study  

Microsoft Academic Search

A multibeam antenna which will be based on a Mars orbiting satellite has been proposed for the Space Exploration Initiative. This antenna would be used for a variety of purposes; besides communicating with fixed bases, the antenna would simultaneously need to communicate with mobile ground terminals mounted on vehicles or robots. Six basic antenna designs are presented, with additional variations

M. L. Zimmerman; S. W. Lee; B. Houshmand; H. Ling

1992-01-01

340

Hilbert curve fractal antennas with reconfigurable characteristics  

Microsoft Academic Search

Fractal Hilbert curve is one of the most recent geometries to be studied for antennas. This geometry results in an antenna with low resonant frequency compared to other configurations. The antenna consists of line segments arranged in a predictable fractal order, thus enabling easy generation and reproducible results compared to an arbitrary shrinkage of antenna size. This can be modeled

K. J. Vinoy; K. A. Jose; V. K. Varadan; V. V. Varadan

2001-01-01

341

High accuracy deployable antenna for communications satellite  

Microsoft Academic Search

High frequency multi-beam satellite antennas have been studied to realize increased communication capacity, simplified earth stations, and multiple frequency reuse. The satellite antenna needs a highly accurate and large reflector. To overcome the launching vehicle's constraints in size and weight, a solid deployable antenna is under development. A petal antenna (PETAL), composed of solid shell elements, has been studied as

M. Watanabe; M. Misawa; M. Minomo; T. Yasaka

1982-01-01

342

Dale Haracre Ceramics In a Patch Antenna  

E-print Network

Wiring Board (PWB) which normally causes electric magnetic radiation in other antenna structures.The most common form of patch antennas being a conductive structure printed on a dielectric substrate over structure of the antenna.An electric field is generated from the edge of the antenna and becomes

Mukhopadhyay, Sharmila M.

343

Microstrip antennas for SAR applications  

NASA Technical Reports Server (NTRS)

Current and future microstrip antenna technology development for Spaceborne Synthetic Aperture Radars (SAR) are summarized. Some of the electrical and mechanical characteristics of previously and presently developed microstrip SAR antennas are shown. The SEASAT, the SIR-A and presently the SIR-B antennas are all designed for operation at L-band with approximately 22 MHz of bandwidth. The antennas have linear polarization with minimum of 20 dB of polarization purity. Both the SEASAT and SIR-A antennas were designed for a fixed pointing angle of 20.5 deg and 47 deg, respectively. However, the SIR-B has the added feature of mechanical beam steering in elevation (range). With the exception of different mechanical characteristics, it is concluded that present spaceborne SAR antennas have only single frequency and single polarization performance. The lack of large spaceborne antennas operating at the higher degree of fabrication tolerance required for a given performance; and larger feed and radiating element losses.

Haddad, H. A.

1983-01-01

344

Ion source with external RF antenna  

DOEpatents

A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source.

Leung, Ka-Ngo; Ji, Qing; Wilde, Stephen

2005-12-13

345

Conformal geodesics in general relativity  

Microsoft Academic Search

Conformal geodesics, space-time curves which are related to conformal structures in a similar way as geodesics are related to metric structures, are discussed. `Conformal normal coordinates', `conformal Gauss systems' and their associated `normal connections', `normal frames' and `normal metrics' are introduced and used to study: (i) asymptotically simple solutions of Ric(g) = Lambda g near conformal infinity, (ii) asymptotically simple

H. Friedrich; B. G. Schmidt

1987-01-01

346

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

347

Multiple-Beam Communications Antenna  

NASA Technical Reports Server (NTRS)

System has both fixed-spot and scanning coverage. Advanced offset-fed spacecraft antenna systems operating in 30/20 GHz frequency bands developed to provide multiple-radiating fixed-spot and regional-coverage scanning beams for use on communications satellites. Operating at higher frequencies, provides alternate frequency bands for expansion of existing satellite services and achieving frequency reuse capability for conservation of frequency spectrum. 20-GHz transmitting antenna is offset-fed, dual-reflector configuration. 30-GHz receiving antenna has orthogonal polarized feeds, hyperbolic reflectors, and two subreflectors.

Myhre, R. W.; Roberts, T. E.; Wong, W. C.

1989-01-01

348

Conical quadreflex antenna analytical study  

NASA Technical Reports Server (NTRS)

A method for evaluating the performance of a four-reflection or quadreflex antenna is reported. Geometrical optics was used initially to determine the ideal feed pattern required to produce uniform illumination on the aperture of the conical reflector and the reverse problem of quickly finding the aperture illumination given an arbitrary feed pattern. The knowledge of the aperture illumination makes it possible to compute the antenna efficiency, which is useful for comparing antenna performance during tradeoff studies. Scattering calculations, using physical optics techniques, were then used to more accurately determine the performance of a specific design.

Cramer, P. W., Jr.

1973-01-01

349

Smart antennas based on graphene  

SciTech Connect

We report two configurations of smart graphene antennas, in which either the radiation pattern of the antenna or the backscattering of the periodic metallic arrays is controlled by DC biases that induce metal-insulator reversible transitions of graphene monolayers. Such a transition from a high surface resistance (no bias) to a low surface resistance state (finite bias voltage) causes the radiation pattern of metallic antennas backed with graphene to change dramatically, from omnidirectional to broadside. Moreover, reflectarrays enhance the backscattered field due to the same metal-dielectric transition.

Aldrigo, Martino; Dragoman, Mircea, E-mail: mircea.dragoman@imt.ro [National Institute for Research and Development in Microtechnology (IMT), P.O. Box 38-160, 023573 Bucharest (Romania); Dragoman, Daniela [Physics Faculty, University of Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania)

2014-09-21

350

Designing Rectangular RHCP Microstrip Antennas  

NASA Technical Reports Server (NTRS)

RHCP, Right-Handed, Circularly Polarized Microstrip Antenna program, aids in design of rectangular microstrip-antenna element, given desired frequency of operation and characteristics of substrate. Begins design calculations on basis of square element with linear polarization. Effective dielectric constant and changes in electrical length due to fringing at edges of radiating element taken into account. Coaxial feed inset with 50 ohms input impedance. Placement of feed such that two orthonormal modes produced in antenna cavity, right- or left-handed circular polarization obtained. Written in FORTRAN 77.

Davidson, Shayla E.

1987-01-01

351

Electrically floating, near vertical incidence, skywave antenna  

DOEpatents

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

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

2014-07-08

352

Massive-Conformal Dictionary  

E-print Network

The finite-volume spectrum of an integrable massive perturbation of a rational conformal field theory interpolates between massive multi-particle states in infinite volume (IR limit) and conformal states, which are approached at zero volume (UV limit). Each state is labeled in the IR by a set of `Bethe Ansatz quantum numbers', while in the UV limit it is characterized primarily by the conformal dimensions of the conformal field creating it. We present explicit conjectures for the UV conformal dimensions corresponding to any IR state in the $\\phi_{1,3}$-perturbed minimal models $M(2,5)$ and $M(3,5)$. The conjectures, which are based on a combinatorial interpretation of the Rogers-Ramanujan-Schur identities, are consistent with numerical results obtained previously for low-lying energy levels.

Ezer Melzer

1993-11-10

353

Antenna sunshield membrane  

NASA Technical Reports Server (NTRS)

An RF-transparent sunshield membrane covers an antenna reflector such as a parabolic dish. The blanket includes a single dielectric sheet of polyimide film 1/2-mil thick. The surface of the film facing away from the reflector is coated with a transparent electrically conductive coating such as vapor-deposited indium-tin oxide. The surface of the film facing the reflector is reinforced by an adhesively attached polyester or glass mesh, which in turn is coated with a white paint. In a particular embodiment of the invention, polyurethane paint is used. In another embodiment of the invention, a layer of paint primer is applied to the mesh under a silicone paint, and the silicone paint is cured after application for several days at room temperature to enhance adhesion to the primer.

Bogorad, Alexander (Inventor); Bowman, Jr., Charles K. (Inventor); Meder, Martin G. (Inventor); Dottore, Frank A. (Inventor)

1994-01-01

354

Phased array acoustic antenna  

SciTech Connect

A system for remote measurement of wind velocity in the atmosphere, operating from ground level. An array of acoustic transducer elements which provide for transmitting a beam of acoustic energy along a path and receiving such transmitted energy as scattered by wind in the path. The system includes signal transmitting means for driving the arrays, and signal receiving means, with a switching system for connecting the elements of the array to the transmitting means and to the receiving means, for operation as a monostatic system. Phase control for the transmitted signals comprising phase shifters and switches for selectively connecting driving signals to the elements of the array for driving selected elements at different phases to produce first, second and third beams in sequence at three different predetermined angles from a single antenna.

Balser, M.; Ambler, F. E.

1985-12-17

355

Metal Patch Antenna  

NASA Technical Reports Server (NTRS)

Disclosed herein is a patch antenna comprises a planar conductive patch attached to a ground plane by a support member, and a probe connector in electrical communication with the conductive patch arranged to conduct electromagnetic energy to or from the conductive patch, wherein the conductive patch is disposed essentially parallel to the ground plane and is separated from the ground plane by a spacing distance; wherein the support member comprises a plurality of sides disposed about a central axis oriented perpendicular to the conductive patch and the ground plane; wherein the conductive patch is solely supported above the ground plane by the support member; and wherein the support member provides electrical communication between the planer conductive patch and the ground plane.

Chamberlain, Neil F. (Inventor); Hodges, Richard E. (Inventor); Zawadzki, Mark S. (Inventor)

2012-01-01

356

Varactor-tuned Active Integrated Antenna Using Slot Antenna Dong-Hyuk Choi* and Seong-Ook Park  

E-print Network

with the varactor. VCO Antenna Design The proposed VCO antenna configuration is shown in Fig. 1. The VCO antenna The VCO antenna is designed using the T-shaped microstrip-line-fed slot antenna. It was found-controlled oscillator (VCO) and a matched slot antenna is proposed. The fabricated antenna has a stable oscillation at 5

Park, Seong-Ook

357

Development of an antenna structure for a deployable offset antenna  

NASA Astrophysics Data System (ADS)

An unfurlable spacecraft antenna is described. The antenna consists of a central hub, ribs being radially arranged around the hub, and a mesh which produces the parabolic reflector surface shape. The hub and the ribs are made of CFRP. For the stowed and deployed reflector configuration the CFRP-components were analyzed and optimized under dynamical and dimensional stability aspects. The analytical results and the development of the CFRP components are presented.

Herbig, H.; Tauber, W.; Vorbrugg, H.

1986-02-01

358

The frequency response of phased-array antennas  

SciTech Connect

The phased-array antenna will be examined from the point of view of effects caused by changes in frequency. Both simple linear arrays and the more complex conformal array are examined. For the conformal array, a comparison between a corporate-feed structure and a row series-feed structure is included. There are two primary effects which will be discussed: beam-pointing errors and distortion of large bandwidth signals. A formula for estimating the operating or tunable array bandwidth for narrow-bandwidth signals is derived. An expression for the wide-bandwidth-signal transfer function is also obtained and examined. It will be shown that the transfer function depends both on the array scan angle and the position within the mainbeam. 25 figs.

Brock, B.C.

1989-02-01

359

Optical antenna design for nanophotodiodes  

Microsoft Academic Search

Guidelines for designing an optical antenna for optimizing the performance of a nanophotodiode are proposed. A nanopatch design is simulated with over 70% absorption efficiency using germanium as the absorber.

Ryan Going; Tae Joon Seok; Amit Lakhani; Michael Eggleston; Myung-Ki Kim; Ming C. Wu

2011-01-01

360

Circularly-Polarized Microstrip Antenna  

NASA Technical Reports Server (NTRS)

Microstrip construction compact for mobile applications. Circularly polarized microstrip antenna made of concentric cylindrical layers of conductive and dielectric materials. Coaxial cable feedlines connected to horizontal and vertical subelements from inside. Vertical subelement acts as ground for horizontal subelement.

Stanton, P. H.

1985-01-01

361

Electrically-driven optical antennas  

E-print Network

Unlike radiowave antennas, optical nanoantennas so far cannot be fed by electrical generators. Instead, they are driven by light or via optically active materials in their proximity. Here, we demonstrate direct electrical driving of an optical nanoantenna featuring an atomic-scale feed gap. Upon applying a voltage, quantum tunneling of electrons across the feed gap creates broadband quantum shot noise. Its optical frequency components are efficiently converted into photons by the antenna. We demonstrate that the properties of the emitted photons are fully controlled by the antenna architecture, and that the antenna improves the quantum efficiency by up to two orders of magnitude with respect to a non-resonant reference system. Our work represents a new paradigm for interfacing electrons and photons at the nanometer scale, e.g. for on-chip wireless data communication, electrically driven single- and multiphoton sources, as well as for background-free linear and nonlinear spectroscopy and sensing with nanometer...

Kern, Johannes; Prangsma, Jord C; Emmerling, Monika; Kamp, Martin; Hecht, Bert

2015-01-01

362

Planar microstrip YAGI antenna array  

NASA Technical Reports Server (NTRS)

A directional microstrip antenna includes a driven patch surrounded by an isolated reflector and one or more coplanar directors, all separated from a ground plane on the order of 0.1 wavelength or less to provide end fire beam directivity without requiring power dividers or phase shifters. The antenna may be driven at a feed point a distance from the center of the driven patch in accordance with conventional microstrip antenna design practices for H-plane coupled or horizontally polarized signals. The feed point for E-plane coupled or vertically polarized signals is at a greater distance from the center than the first distance. This feed point is also used for one of the feed signals for circularly polarized signals. The phase shift between signals applied to feed points for circularly polarized signals must be greater than the conventionally required 90 degrees and depends upon the antenna configuration.

Huang, John (inventor)

1993-01-01

363

Inflatable Antennas Support Emergency Communication  

NASA Technical Reports Server (NTRS)

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

2010-01-01

364

Self-phasing array antennas  

Microsoft Academic Search

A self-phasing array antenna is described which operates on the incident wavefront in such a manner that when it is retransmitted it returns whence it came as a coherent wavefront irrespective of the original phase distribution incident on the array. Self-phasing is useful where a two-way propagation path is available and where a conventional antenna cannot operate efficiently because of

M. Skolnik; D. King

1964-01-01

365

Input impedance of microstrip antennas  

NASA Technical Reports Server (NTRS)

Using Richmond's reaction integral equation, an expression is derived for the input impedance of microstrip patch antennas excited by either a microstrip line or a coaxial probe. The effects of the finite substrate thickness, a dielectric protective cover, and associated surface waves are properly included by the use of the exact dyadic Green's function. Using the present formulation the input impedance of a rectangular microstrip antenna is determined and compared with experimental and earlier calculated results.

Deshpande, M. D.; Bailey, M. C.

1982-01-01

366

Antennas for mobile satellite communications  

NASA Technical Reports Server (NTRS)

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

1991-01-01

367

Conformal Carroll groups  

NASA Astrophysics Data System (ADS)

Conformal extensions of Lévy-Leblond's Carroll group, based on geometric properties analogous to those of Newton-Cartan space-time are proposed. The extensions are labeled by an integer k. This framework includes and extends our recent study of the Bondi-Metzner-Sachs (BMS) and Newman-Unti (NU) groups. The relation to conformal Galilei groups is clarified. Conformal Carroll symmetry is illustrated by ‘Carrollian photons’. Motion both in the Newton-Cartan and Carroll spaces may be related to that of strings in the Bargmann space.

Duval, C.; Gibbons, G. W.; Horvathy, P. A.

2014-08-01

368

Spinning Conformal Correlators  

E-print Network

We develop the embedding formalism for conformal field theories, aimed at doing computations with symmetric traceless operators of arbitrary spin. We use an index-free 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.

Miguel S. Costa; Joao Penedones; David Poland; Slava Rychkov

2015-01-23

369

Mobile antenna development at JPL  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory (JPL), under the sponsorship of NASA, has pioneered the development of land vehicle antennas for commercial mobile satellite communications. Several novel antennas have been developed at L-band frequencies for the Mobile Satellite (MSAT) program initiated about a decade ago. Currently, two types of antennas are being developed at K- and Ka-band frequencies for the ACTS (Advanced Communications Technology Satellite) Mobile Terminal (AMT) project. For the future, several hand-held antenna concepts are proposed for the small terminals of the Ka-band Personal Access Satellite System (PASS). For the L-band MSAT program, a number of omni-directional low-gain antennas, such as the crossed drooping-dipoles, the higher-order-mode circular microstrip patch, the quadrifilar helix, and the wrapped-around microstrip 'mast' array, have been developed for lower data rate communications. Several medium-gain satellite tracking antennas, such as the electronically scanned low-profile phased array, the mechanically steered tilted microstrip array, the mechanically steered low-profile microstrip Yagi array, and the hybrid electronically/mechanically steered low-profile array, have been developed for the MSAT's higher data rate and voice communications. To date, for the L-band vehicle application, JPL has developed the world's lowest-profile phased array (1.8 cm height), as well as the lowest-profile mechanically steered antenna (3.7 cm height). For the 20/30 GHz AMT project, a small mechanically steered elliptical reflector antenna with a gain of 23 dBi has recently been developed to transmit horizontal polarization at 30 GHz and receive vertical polarization at 20 GHz. Its hemispherical radome has a height of 10 cm and a base diameter of 23 cm. In addition to the reflector, a mechanically steered printed MMIC active array is currently being developed to achieve the same electrical requirements with a low profile capability. These AMT antenna developments, along with other Ka-band technologies, will lead to the development of several compact hand-held terminals for the PASS program. A few antenna concepts, such as the lap-top or desk-top terminal's printed array, the hand-held phased array, and the head-mounted low-profile array, have been proposed to achieve a future vision for the personal access communications system.

Huang, J.; Jamnejad, V.; Densmore, A.; Tulintseff, A.; Thomas, R.; Woo, K.

1993-01-01

370

Conformal and non conformal dilaton gravity  

NASA Astrophysics Data System (ADS)

The quantum dynamics of the gravitational field non-minimally coupled to an (also dynamical) scalar field is studied in the broken phase. For a particular value of the coupling the system is classically conformal, and can actually be understood as the group averaging of Einstein-Hilbert's action under conformal transformations. Conformal invariance implies a simple Ward identity asserting that the trace of the equation of motion for the graviton is the equation of motion of the scalar field. We perform an explicit one-loop computation to show that the DeWitt effective action is not UV divergent on shell and to find that the Weyl symmetry Ward identity is preserved on shell at that level. We also discuss the fate of this Ward identity at the two-loop level — under the assumption that the two-loop UV divergent part of the effective action can be retrieved from the Goroff-Sagnotti counterterm — and show that its preservation in the renormalized theory requires the introduction of counterterms which exhibit a logarithmic dependence on the dilaton field.

Alvarez, Enrique; Herrero-Valea, Mario; Martín, C. P.

2014-10-01

371

Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles  

NASA Technical Reports Server (NTRS)

A low-cost beamformer phased array antenna has been developed for expendable launch vehicles, rockets, and missiles. It utilizes a conformal array antenna of ring or individual radiators (design varies depending on application) that is designed to be fed by the recently developed hybrid electrical/mechanical (vendor-supplied) phased array beamformer. The combination of these new array antennas and the hybrid beamformer results in a conformal phased array antenna that has significantly higher gain than traditional omni antennas, and costs an order of magnitude or more less than traditional phased array designs. Existing omnidirectional antennas for sounding rockets, missiles, and expendable launch vehicles (ELVs) do not have sufficient gain to support the required communication data rates via the space network. Missiles and smaller ELVs are often stabilized in flight by a fast (i.e. 4 Hz) roll rate. This fast roll rate, combined with vehicle attitude changes, greatly increases the complexity of the high-gain antenna beam-tracking problem. Phased arrays for larger ELVs with roll control are prohibitively expensive. Prior techniques involved a traditional fully electronic phased array solution, combined with highly complex and very fast inertial measurement unit phased array beamformers. The functional operation of this phased array is substantially different from traditional phased arrays in that it uses a hybrid electrical/mechanical beamformer that creates the relative time delays for steering the antenna beam via a small physical movement of variable delay lines. This movement is controlled via an innovative antenna control unit that accesses an internal measurement unit for vehicle attitude information, computes a beam-pointing angle to the target, then points the beam via a stepper motor controller. The stepper motor on the beamformer controls the beamformer variable delay lines that apply the appropriate time delays to the individual array elements to properly steer the beam. The array of phased ring radiators is unique in that it provides improved gain for a small rocket or missile that uses spin stabilization for stability. The antenna pattern created is symmetric about the roll axis (like an omnidirectional wraparound), and is thus capable of providing continuous coverage that is compatible with very fast spinning rockets. For larger ELVs with roll control, a linear array of elements can be used for the 1D scanned beamformer and phased array, or a 2D scanned beamformer can be used with an NxN element array.

Mullinix, Daniel; Hall, Kenneth; Smith, Bruce; Corbin, Brian

2012-01-01

372

47 CFR 17.4 - Antenna structure registration.  

Code of Federal Regulations, 2013 CFR

...the proposed new antenna structure or modification of an existing antenna structure...proposed antenna structure or physical modification of an existing antenna structure may...Structure Registration Number must be weather-resistant and of sufficient size...

2013-10-01

373

47 CFR 17.4 - Antenna structure registration.  

Code of Federal Regulations, 2012 CFR

...the proposed new antenna structure or modification of an existing antenna structure...proposed antenna structure or physical modification of an existing antenna structure may...Structure Registration Number must be weather-resistant and of sufficient size...

2012-10-01

374

Vehicle antenna development for mobile satellite applications  

NASA Technical Reports Server (NTRS)

The paper summarizes results of a vehicle antenna program at JPL in support of a developing U.S. mobile satellite services (MSS) designed to provide telephone and data services for the continental United States. Two classes of circularly polarized vehicle antennas have been considered for the MSS: medium-gain, satellite-tracking antennas with 10-12-dBic gain; and low-gain, azimuthally omnidirectional antennas with 3-5-dBic gain. The design and performance of these antennas are described, and the two antennas are shown to have peculiar advantages and disadvantages.

Woo, K.

1988-01-01

375

Satellite Communications with NRAO Green Bank Antennas  

NASA Astrophysics Data System (ADS)

The National Radio Astronomy Observatory's Green Bank facility has several medium and large antennas that are available for satellite communications. The 100 meter Robert C. Byrd Green Bank Telescope (GBT), the largest and most sensitive antenna on site, is capable of receiving signals at frequencies as high as 86 GHz. In addition to the GBT are the fully operational 43 meter, 20 meter, and 13.7 meter antennas, and three mothballed 26 meter antennas. A transmitter could be fitted to any of these antennas for spacecraft uplinks. We discuss the characteristics of these antennas and possible operational models for future planetary science mission support.

Ford, John M.; Ford, H. Alyson; Watts, Galen

2014-11-01

376

Imaging Antenna Structure For Submillimeter Wavelengths  

NASA Technical Reports Server (NTRS)

Integrated-circuit antenna structure contains two-dimensional array of antennas and antenna reflectors. In receiving mode, each antenna acts as part of detector for one picture element in millimeter- or submillimeter-wavelength imaging radar system. Millimeter-wave imaging system used to view objects through fog, smoke, or smog with resolution intermediate between microwave and visible-light imaging systems. Antenna elements, supports, and reflectors made by integrated-circuit techniques. Structures fabricated on front and back substrates separately. Substrates then joined. Inexpensive way to provide large number of small antenna elements required for imaging, all mounted rigidly in way that does not degrade operation.

Rebeiz, G.; Rutledge, D.

1990-01-01

377

Axiomatic Conformal Field Theory  

Microsoft Academic Search

:  A new rigourous approach to conformal field theory is presented. The basic objects are families of complex-valued amplitudes,\\u000a which define a meromorphic conformal field theory (or chiral algebra) and which lead naturally to the definition of topological\\u000a vector spaces, between which vertex operators act as continuous operators. In fact, in order to develop the theory, Möbius\\u000a invariance rather than full

Matthias R. Gaberdiel; Peter Goddard

2000-01-01

378

Assemblies of Conformal Tanks  

NASA Technical Reports Server (NTRS)

Assemblies of tanks having shapes that conform to each other and/or conform to other proximate objects have been investigated for use in storing fuels and oxidizers in small available spaces in upper stages of spacecraft. Such assemblies might also prove useful in aircraft, automobiles, boats, and other terrestrial vehicles in which space available for tanks is limited. The basic concept of using conformal tanks to maximize the utilization of limited space is not new in itself: for example, conformal tanks are used in some automobiles to store windshield -washer liquid and coolant that overflows from radiators. The novelty of the present development lies in the concept of an assembly of smaller conformal tanks, as distinguished from a single larger conformal tank. In an assembly of smaller tanks, it would be possible to store different liquids in different tanks. Even if the same liquid were stored in all the tanks, the assembly would offer an advantage by reducing the mechanical disturbance caused by sloshing of fuel in a single larger tank: indeed, the requirement to reduce sloshing is critical in some applications. The figure shows a prototype assembly of conformal tanks. Each tank was fabricated by (1) copper plating a wax tank mandrel to form a liner and (2) wrapping and curing layers of graphite/epoxy composite to form a shell supporting the liner. In this case, the conformal tank surfaces are flat ones where they come in contact with the adjacent tanks. A band of fibers around the outside binds the tanks together tightly in the assembly, which has a quasi-toroidal shape. For proper functioning, it would be necessary to maintain equal pressure in all the tanks.

DeLay, Tom

2009-01-01

379

Feed Structure For Antennas  

NASA Technical Reports Server (NTRS)

A novel feed structure, for an antenna having a resonant electric field structure, comprising a patch element, an integrated circuit attached to the patch element, at least one inner conductor electrically connected to and terminating at the integrated circuit on a first end of the at least one inner conductor, wherein the at least one inner conductor extends through and is not electrically connected to the patch element, and wherein the at least one inner conductor is available for electrical connectivity on a second end of the at least one inner conductor, and an outer conductor electrically connected to and terminating at the patch element on a first end of the outer conductor, wherein the outer conductor is available for electrical connectivity on a second end of the outer conductor, and wherein the outer conductor concentrically surrounds the at least one inner conductor from the second end of the at least one inner conductor available for electrical connectivity to the first end of the outer conductor terminating at the patch element.

Fink, Patrick W. (Inventor); Chu, Andrew W. (Inventor); Dobbins, Justin A. (Inventor); Lin, Greg Y. (Inventor)

2005-01-01

380

Wide scanning spherical antenna  

NASA Technical Reports Server (NTRS)

A novel method for calculating the surface shapes for subreflectors in a suboptic assembly of a tri-reflector spherical antenna system is introduced, modeled from a generalization of Galindo-Israel's method of solving partial differential equations to correct for spherical aberration and provide uniform feed to aperture mapping. In a first embodiment, the suboptic assembly moves as a single unit to achieve scan while the main reflector remains stationary. A feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan thereby eliminating the need to oversize the main spherical reflector. In an alternate embodiment, both the main spherical reflector and the suboptic assembly are fixed. A flat mirror is used to create a virtual image of the suboptic assembly. Scan is achieved by rotating the mirror about the spherical center of the main reflector. The feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan.

Shen, Bing (Inventor); Stutzman, Warren L. (Inventor)

1995-01-01

381

Conformational sampling techniques.  

PubMed

The potential energy hyper-surface of a protein relates the potential energy of the protein to its conformational space. This surface is useful in determining the native conformation of a protein or in examining a statistical-mechanical ensemble of structures (canonical ensemble). In determining the potential energy hyper-surface of a protein three aspects must be considered; reducing the degrees of freedom, a method to determine the energy of each conformation and a method to sample the conformational space. For reducing the degrees of freedom the choice of solvent, coarse graining, constraining degrees of freedom and periodic boundary conditions are discussed. The use of quantum mechanics versus molecular mechanics and the choice of force fields are also discussed, as well as the sampling of the conformational space through deterministic and heuristic approaches. Deterministic methods include knowledge-based statistical methods, rotamer libraries, homology modeling, the build-up method, self-consistent electrostatic field, deformation methods, tree-based elimination and eigenvector following routines. The heuristic methods include Monte Carlo chain growing, energy minimizations, metropolis monte carlo and molecular dynamics. In addition, various methods to enhance the conformational search including the deformation or smoothing of the surface, scaling of system parameters, and multi copy searching are also discussed. PMID:23947647

Hatfield, Marcus P D; Lovas, Sándor

2014-01-01

382

Conformations of antipyrines.  

PubMed

Reliable conformational energetics is essential in interpreting and predicting structures of molecular crystals. We provide a combined density functional theory (DFT)-structural database study, demonstrating that this combination can be used as a foundation for this purpose. A subtle problem of nitrogen pyramidalization is used as the example in antipyrines, a group of bioactive molecules. Nitrogen pyramidalization on the two adjacent sp(3) nitrogens directly affects the orientation of the methyl and phenyl substituents, which tend toward opposite sides of the heteroaromatic ring, affecting crystal packing. Accordingly, the overwhelming majority of the structures of antipyrines in the Cambridge Structural Database (CSD) are either nearly planar or have substituents on the opposite sides of the ring. Recent powder X-ray structures by Lemmerer et al. identified propyphenazone, an antipyrine, to have two substituents on the same side in an apparently sterically crowded conformation. We show that the new structure, although counterintuitive, is not an outlier on the conformational map. A distribution of the conformations of all antipyrines listed in the CSD is in good agreement with the computed conformational map. We also examine the role of the hysteretic property of the phenyl torsion in propyphenazone and its indirect effects on its overall conformation. PMID:21491880

Roumanos, Michael; Kertesz, Miklos

2011-05-12

383

Reduction of RF-sheaths potentials by compensation or suppression of parallel RF currents on ICRF antennas  

NASA Astrophysics Data System (ADS)

Radio frequency (RF) sheaths are suspected of limiting the performance of present-day ion cyclotron range of frequencies (ICRFs) antennas over long pulses and should be minimized in future fusion devices. Within the simplest models, RF-sheath effects are quantified by the integral VRF = ? Epar · dl where the parallel RF field Epar is linked with the slow wave. On 'long open field lines' with large toroidal extension on both sides of the antenna it was shown that VRF is excited by parallel RF currents jpar flowing on the antenna structure. In this paper, the validity of this simple sheath theory is tested experimentally on the Tore Supra (TS) ITER-like antenna prototype (ILP), together with antenna simulation and post-processing codes developed to compute VRF. The predicted poloidal localization of high-|VRF| zones is confronted to that inferred from experimental data analysis. Surface temperature distribution on ILP front face, as well as ILP-induced modifications of RF coupling and hot spots on a magnetically connected lower hybrid current drive antenna, indicates local maxima of dc plasma potential in both the upper and lower parts of the ILP. This result, qualitatively conforming to VRF simulations, is interpreted in terms of jpar flowing on ILP frame. Once the validation is done, such reliable theoretical models and numerical codes are then employed to provide predictive results. Indeed, we propose two ways to reduce |VRF| by acting on jpar on the antenna front face. The first method, more adapted for protruding antennas, consists of avoiding the jpar circulation on the antenna structure, by slotting the antenna frame on its horizontal edges and by partially cutting the Faraday screen rods. The second method, well suited for recessed antennas, consists of compensating jpar of opposite signs along long flux tubes, with parallelepiped antennas aligned with (tilted) flux tubes. The different concepts are assessed numerically on a two-strap TS antenna phased [0, ?] using near RF fields from the antenna code TOPICA. Simulations stress the need to suppress all current paths for jpar to substantially reduce |VRF| over the whole antenna height.

Mendes, A.; Colas, L.; Vulliez, K.; Ekedahl, A.; Argouarch, A.; Milanesio, D.

2010-02-01

384

The TV broadcasting and telecommunication antennas of Olympus satellite  

Microsoft Academic Search

The 12 GHz TV broadcasting antennas and the 20\\/30 GHz telecommunication antennas of the Olympus satellite are discussed, noting that WARC 77 requirements have had a direct impact on the selection of an antenna configuration. Required antenna geometry and coverage of the 20\\/30 GHz communication antennas is also treated in detail. The targets of an antenna farm analysis are twofold:

Giulio Doro Altan

1989-01-01

385

Measured and predicted root-mean-square errors in square and triangular antenna mesh facets  

NASA Technical Reports Server (NTRS)

Deflection shapes of square and equilateral triangular facets of two tricot-knit, gold plated molybdenum wire mesh antenna materials were measured and compared, on the basis of root mean square (rms) differences, with deflection shapes predicted by linear membrane theory, for several cases of biaxial mesh tension. The two mesh materials contained approximately 10 and 16 holes per linear inch, measured diagonally with respect to the course and wale directions. The deflection measurement system employed a non-contact eddy current proximity probe and an electromagnetic distance sensing probe in conjunction with a precision optical level. Despite experimental uncertainties, rms differences between measured and predicted deflection shapes suggest the following conclusions: that replacing flat antenna facets with facets conforming to parabolically curved structural members yields smaller rms surface error; that potential accuracy gains are greater for equilateral triangular facets than for square facets; and that linear membrane theory can be a useful tool in the design of tricot knit wire mesh antennas.

Fichter, W. B.

1989-01-01

386

Patch antenna based temperature sensor  

NASA Astrophysics Data System (ADS)

In this paper, we studied the microstrip patch antenna for the purpose of temperature sensing. The relationship between the antenna resonant frequency shift and temperature variation is first derived based on the transmission line model. A substrate material was selected to achieve a linear sensor response. Temperature chamber tests on patch antenna sensors bonded to three different test samples were carried out. Preliminary experimental results indicated a linear relation between the normalized antenna resonant frequency changes and temperature variations. However, a large discrepancy between the measured and predicted sensitivities was observed, which indicated that the thermal strain might have a significant influence on the dielectric constant of the substrate. To account for this effect, we introduced a strain coefficient of dielectric constant to quantify the effect of strain on the dielectric constant. With the modified theoretical predictions, the errors between the measurements and predictions were within the systematic error of the reference thermocouple, which validates the feasibility of using a microstrip patch antenna for temperature sensing.

Jiang, Hao; Sanders, Jeremiah; Yao, Jun; Huang, Haiying

2014-04-01

387

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1 Gain Enhancement of a Microstrip Patch Antenna  

E-print Network

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1 Gain Enhancement of a Microstrip Patch Antenna, Senior Member, IEEE, Abstract-- In this paper, the performance of a circular mi- crostrip patch antenna is improved using a new cylindrical Electromagnetic Bandgap (EBG) substrate. The microstrip patch antenna

Paris-Sud XI, Université de

388

A cognitive radio antenna design based on optically pumped reconfigurable antenna system (OPRAS)  

Microsoft Academic Search

This paper presents a new antenna scheme for cognitive radio communication. The antenna structure consists of two ports. The first antenna port is a UWB structure for channel sensing while the second one is a reconfigurable structure for communication. The reconfigurability is based on integrating laser diodes within the antenna substrate in order to activate the photoconductive switches. A prototype

Y. Tawk; S. Hemmady; C. G. Christodoulou; J. Costantine; G. Balakrishnan

2011-01-01

389

47 CFR 80.863 - Antenna system.  

Code of Federal Regulations, 2014 CFR

...is suspended between masts or other supports liable to whipping, a safety link which, under heavy stress, will operate to greatly reduce such stress without breakage of the antenna, the halyards, or other antenna-supporting elements, must...

2014-10-01

390

New Method of Antenna Arrays Pattern Synthesis  

Microsoft Academic Search

New method of pattern synthesis of antenna arrays without phase shifters and attenuators has been presented. This concept is based on utilizing voltage-controlled ferroelectric array, where variable pattern of each antenna element is used to synthesize array pattern.

Jozef Modelski; Yevhen Yashchyshyn

2001-01-01

391

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

392

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN  

E-print Network

DEPLOYABLE ANTENNA KINEMATICS USING TENSEGRITY STRUCTURE DESIGN By BYRON FRANKLIN KNIGHT This research has been a labor of love, beginning with my first job as a "new grad" building deployable antenna .........................................................................................................5 Tensegrity Overview

Florida, University of

393

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2013 CFR

...excluding second receiving antennas for operations such as space diversity) meeting the appropriate performance Standard A indicated...e) Periscope antennas used at an electric power facility plant area will be excluded from the requirements of...

2013-10-01

394

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2011 CFR

...excluding second receiving antennas for operations such as space diversity) meeting the appropriate performance Standard A indicated...e) Periscope antennas used at an electric power facility plant area will be excluded from the requirements of...

2011-10-01

395

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2014 CFR

...excluding second receiving antennas for operations such as space diversity) meeting the appropriate performance Standard A indicated...e) Periscope antennas used at an electric power facility plant area will be excluded from the requirements of...

2014-10-01

396

47 CFR 101.115 - Directional antennas.  

Code of Federal Regulations, 2010 CFR

...excluding second receiving antennas for operations such as space diversity) meeting the appropriate performance Standard A indicated...e) Periscope antennas used at an electric power facility plant area will be excluded from the requirements of...

2010-10-01

397

Progress on conformal microwave array applicators for heating chestwall disease  

NASA Astrophysics Data System (ADS)

Previous studies have reported the computer modeling, CAD design, and theoretical performance of single and multiple antenna arrays of Dual Concentric Conductor (DCC) square slot radiators driven at 915 and 433 MHz. Subsequently, practical CAD designs of microstrip antenna arrays constructed on thin and flexible printed circuit board (PCB) material were reported which evolved into large Conformal Microwave Array (CMA) sheets that could wrap around the surface of the human torso for delivering microwave energy to large areas of superficial tissue. Although uniform and adjustable radiation patterns have been demonstrated from multiple element applicators radiating into simple homogeneous phantom loads, the contoured and heterogeneous tissue loads typical of chestwall recurrent breast cancer have required additional design efforts to achieve good coupling and efficient heating from the increasingly larger conformal array applicators used to treat large area contoured patient anatomy. Thus recent work has extended the theoretical optimization of DCC antennas to improve radiation efficiency of each individual aperture and reduce mismatch reflections, radiation losses, noise, and cross coupling of the feedline distribution network of large array configurations. Design improvements have also been incorporated into the supporting bolus structure to maintain effective coupling of DCC antennas into contoured anatomy and to monitor and control surface temperatures under the entire array. New approaches for non-invasive monitoring of surface and sub-surface tissue temperatures under each independent heat source are described that make use of microwave radiometry and flexible sheet grid arrays of thermal sensors. Efforts to optimize the clinical patient interface and move from planar rectangular shapes to contoured vest applicators that accommodate entire disease in a larger number of patients are summarized. By applying heat more uniformly to large areas of contoured anatomy, the CMA applicator resulting from these enhancements should expand the number of patients that can benefit from effective heating of superficial disease in combination with radiation or chemotherapy.

Stauffer, P. R.; Maccarini, P. F.; Juang, T.; Jacobsen, S. K.; Gaeta, C. J.; Schlorff, J. L.; Milligan, A. J.

2007-02-01

398

Phased array antennas for aeronautical satellite communications  

NASA Astrophysics Data System (ADS)

In this paper, the configurations and the electrical characteristics of a microstrip array antenna (MSA) and a cross-slot array antenna (XSA), which are phased array antennas developed for aeronautical satellite communications, are described. Photographs and element arrangement of MSA and XSA are shown. The feed system of the phased array antenna satisfying the G/T of about 13 dBK and EIRP of 29 dBW is discussed.

Yasunaga, M.; Watanabe, F.; Shiokawa, T.; Yamada, M.

399

Dual-band wearable textile antenna  

Microsoft Academic Search

Future utilization of smart clothing will necessitate applications of multi-function and multifrequency wearable antennas. This work addresses the development of a dual-band textile antenna for wearable applications. The antenna is for GSM operation in the 1900 MHz band and for WLAN operation in the 2.4 GHz band. The proposed antenna has a U-shaped slot-structure mounted on the surface of fleece

Pekka Salonen; Yahya Rahmat-Samii; Heli Hurme; Markku Kivikoski

2004-01-01

400

The Galileo high gain antenna deployment anomaly  

NASA Technical Reports Server (NTRS)

On April 11, 1991, the Galileo spacecraft executed a sequence that would open the spacecraft's High Gain Antenna. The Antenna's launch restraint had been released just after deployment sequence, the antenna, which opens like an umbrella, never reached the fully deployed position. The analyses and tests that followed allowed a conclusive determination of the likely failure mechanisms and pointed to some strategies to use for recovery of the high gain antenna.

Johnson, Michael R.

1994-01-01

401

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

402

Large Space Antenna Systems Technology, 1984  

NASA Technical Reports Server (NTRS)

Papers are presented which provide a comprehensive review of space missions requiring large antenna systems and of the status of key technologies required to enable these missions. Topic areas include mission applications for large space antenna systems, large space antenna structural systems, materials and structures technology, structural dynamics and control technology, electromagnetics technology, large space antenna systems and the space station, and flight test and evaluation.

Boyer, W. J. (compiler)

1985-01-01

403

Antenna Control Systems: From PI to H  

Microsoft Academic Search

This paper discusses the compensation of antenna-pointing errors following the recent analysis and retrofit of the NASA Deep Space Network antenna-control systems. The desired high-frequency communications with spacecraft (at Ka-band) require improved pointing precision over lower-frequency communications (at X-band). The quality of the antenna drives (hardware), the control algorithm (software), and the physical structure of the antenna (in terms of

Wodek Gawronski

2009-01-01

404

Non-Reciprocal Optical Antennas  

E-print Network

Plasmonics aims to interface photonics and electronics. Finding optical, near-field analogues of much used electro-technical components is crucial to the success of such a platform. Here we present the plasmonic analogue of a non-reciprocal antenna. For non-reciprocality in a plasmonic context, the optical excitation and emission resonances of the antenna need to be an orthogonal set. We show that nonlinear excitation of metal nanoantennas creates a sufficient shift between excitation and emission wavelengths that they can be interpreted as decoupled, allowing for independent tuning of excitation and emission properties along different spatial dimensions. This leads, for given excitation wavelength and polarization, to independent optimization of emission intensity, frequency spectrum, polarization and angular spectrum. Non-reciprocal optical antennas of both gold and aluminum are characterized and shown to be useful as e.g. nonlinear signal transducers or nanoscale sources of widely tunable light.

Castro-Lopez, Marta; van Hulst, Niek F

2014-01-01

405

Antenna Technology Shuttle Experiment (ATSE)  

NASA Technical Reports Server (NTRS)

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

1987-01-01

406

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

407

Offset unfurlable antenna, phase 1  

NASA Astrophysics Data System (ADS)

The configuration, technology requirements, development aspects, and experimental activities for satellite reflectors for fixed and mobile communications and television broadcasting are outlined. A 4.5 m antenna for 4 GHz, and an 8 m antenna for 1.6 GHz were studied, assuming an L-Sat type satellite. A radial rib concept with auxiliary adjustment ribs, and a three dimensional scissors concept (spatial framework) with mesh adjustment elements were compared concerning mass, stowage, volume, development risk, and reliability. For antennas of diameter from 3.6 to 12 m (12 GHz to 800 MHz) the radial rib reflector is preferred. Main advantages (with rib folding for larger reflector diameters) are: lower costs; less critical technology problems; lower development risks; high deployment reliability; lightweight intermediate ribs can adapt surface accuracy to higher frequency requirements (high application flexibility); and folded main ribs provide high package capability at larger diameters. The scissors concept is advantageous for applications requiring reflectors from 12 m diameter onwards.

1984-03-01

408

Large Deployable Antenna Shuttle Experiment  

NASA Technical Reports Server (NTRS)

An experiment designed to use the Space Shuttle in tests of the mechanical and electrical properties of spaceborne deployable antennas under zero-gravity conditions is outlined. Space-erectable 20-meter diameter phased arrays or reflector/feed systems, and self-deploying mechanisms, are to be tested. Reflector surface integrity will be tested by an AM laser technique, and electrical behavior will be tested by a spin-stabilized RF beacon injected into orbit prior to unfurlment of the antenna. Focusing and gain measurements, static pattern measurements, dynamic RF gain measurements, and measurements of cross-polarized signals will be conducted, and the reflector will be illuminated by separate feeds for the S-, X-, and K-bands. Mechanical features of the mesh-wrapped rib furlable antenna design are described.

Freeland, R. E.; Smith, J. G.; Springett, J. C.; Woo, K. E.

1975-01-01

409

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

410

Optically addressed ultra-wideband phased antenna array  

NASA Astrophysics Data System (ADS)

Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization techniques for both single and array antennas. In addition, a prototype transmitting phased array system is developed and shown to demonstrate large bandwidth as well as a beam steering capability. The architecture of this system can be further developed to a large-scale array at higher frequencies such as mm-wave. This solution serves as a candidate for UWB multifunctional frontends.

Bai, Jian

411

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.

412

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antennas. 95.859 Section 95.859 ...Technical Standards § 95.859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height...

2012-10-01

413

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2013 CFR

... 5 2013-10-01 2013-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in a GMRS system and...

2013-10-01

414

47 CFR 80.863 - Antenna system.  

Code of Federal Regulations, 2012 CFR

... 5 2012-10-01 2012-10-01 false Antenna system. 80.863 Section 80.863 Telecommunication...Vessels Not Subject to Subpart W § 80.863 Antenna system. (a) An antenna system must be installed which is as...

2012-10-01

415

47 CFR 74.737 - Antenna location.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna location. 74.737 Section 74.737...and TV Booster Stations § 74.737 Antenna location. (a) An applicant...retransmitted. (b) The transmitting antenna should be placed above growing...

2014-10-01

416

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna systems. 73.510 Section 73.510...Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial...the provisions of § 73.316 concerning antenna systems contained in subpart B of...

2013-10-01

417

47 CFR 74.641 - Antenna systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna systems. 74.641 Section 74.641...Broadcast Auxiliary Stations § 74.641 Antenna systems. (a) For fixed stations...auxiliary stations shall use directional antennas that meet the performance...

2013-10-01

418

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna systems. 73.510 Section 73.510...Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial...the provisions of § 73.316 concerning antenna systems contained in subpart B of...

2014-10-01

419

47 CFR 74.737 - Antenna location.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna location. 74.737 Section 74.737...and TV Booster Stations § 74.737 Antenna location. (a) An applicant...retransmitted. (b) The transmitting antenna should be placed above growing...

2012-10-01

420

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2010 CFR

... 5 2010-10-01 2010-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in a GMRS system and...

2010-10-01

421

47 CFR 74.641 - Antenna systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna systems. 74.641 Section 74.641...Broadcast Auxiliary Stations § 74.641 Antenna systems. (a) For fixed stations...auxiliary stations shall use directional antennas that meet the performance...

2011-10-01

422

47 CFR 74.641 - Antenna systems.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna systems. 74.641 Section 74.641...Broadcast Auxiliary Stations § 74.641 Antenna systems. (a) For fixed stations...auxiliary stations shall use directional antennas that meet the performance...

2014-10-01

423

47 CFR 78.105 - Antenna systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna systems. 78.105 Section 78.105... Technical Regulations § 78.105 Antenna systems. (a) For fixed stations...Fixed CARS stations shall use directional antennas that meet the performance standards...

2011-10-01

424

47 CFR 74.641 - Antenna systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna systems. 74.641 Section 74.641...Broadcast Auxiliary Stations § 74.641 Antenna systems. (a) For fixed stations...auxiliary stations shall use directional antennas that meet the performance...

2010-10-01

425

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antennas. 95.859 Section 95.859 ...Technical Standards § 95.859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height...

2013-10-01

426

47 CFR 78.105 - Antenna systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna systems. 78.105 Section 78.105... Technical Regulations § 78.105 Antenna systems. (a) For fixed stations...Fixed CARS stations shall use directional antennas that meet the performance standards...

2013-10-01

427

47 CFR 74.737 - Antenna location.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna location. 74.737 Section 74.737...and TV Booster Stations § 74.737 Antenna location. (a) An applicant...retransmitted. (b) The transmitting antenna should be placed above growing...

2010-10-01

428

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antennas. 95.859 Section 95.859 ...Technical Standards § 95.859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height...

2010-10-01

429

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antennas. 95.859 Section 95.859 ...Technical Standards § 95.859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height...

2011-10-01

430

47 CFR 74.641 - Antenna systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna systems. 74.641 Section 74.641...Broadcast Auxiliary Stations § 74.641 Antenna systems. (a) For fixed stations...auxiliary stations shall use directional antennas that meet the performance...

2012-10-01

431

47 CFR 74.737 - Antenna location.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna location. 74.737 Section 74.737...and TV Booster Stations § 74.737 Antenna location. (a) An applicant...retransmitted. (b) The transmitting antenna should be placed above growing...

2011-10-01

432

47 CFR 78.105 - Antenna systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna systems. 78.105 Section 78.105... Technical Regulations § 78.105 Antenna systems. (a) For fixed stations...Fixed CARS stations shall use directional antennas that meet the performance standards...

2012-10-01

433

47 CFR 80.863 - Antenna system.  

Code of Federal Regulations, 2013 CFR

... 5 2013-10-01 2013-10-01 false Antenna system. 80.863 Section 80.863 Telecommunication...Vessels Not Subject to Subpart W § 80.863 Antenna system. (a) An antenna system must be installed which is as...

2013-10-01

434

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2012 CFR

... 5 2012-10-01 2012-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in a GMRS system and...

2012-10-01

435

47 CFR 74.737 - Antenna location.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antenna location. 74.737 Section 74.737...and TV Booster Stations § 74.737 Antenna location. (a) An applicant...retransmitted. (b) The transmitting antenna should be placed above growing...

2013-10-01

436

47 CFR 78.105 - Antenna systems.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antenna systems. 78.105 Section 78.105... Technical Regulations § 78.105 Antenna systems. (a) For fixed stations...Fixed CARS stations shall use directional antennas that meet the performance standards...

2014-10-01

437

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Antenna systems. 73.510 Section 73.510...Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial...the provisions of § 73.316 concerning antenna systems contained in subpart B of...

2011-10-01

438

Stacked optical antennas Dieter W. Pohl,1  

E-print Network

Stacked optical antennas Dieter W. Pohl,1 Sergio G. Rodrigo,2 and Lukas Novotny2,a 1 Institute; published online 13 January 2011 We propose and analyze a stacked optical antenna SOA . It is characterized in microscopy. © 2011 American Institute of Physics. doi:10.1063/1.3541544 Optical antennas are devices

Novotny, Lukas

439

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Antenna systems. 73.510 Section 73.510...Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial...the provisions of § 73.316 concerning antenna systems contained in subpart B of...

2012-10-01

440

47 CFR 73.510 - Antenna systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna systems. 73.510 Section 73.510...Educational FM Broadcast Stations § 73.510 Antenna systems. (a) All noncommercial...the provisions of § 73.316 concerning antenna systems contained in subpart B of...

2010-10-01

441

Small X-Band Oscillator Antennas  

NASA Technical Reports Server (NTRS)

A small, segmented microstrip patch antenna integrated with an X-band feedback oscillator on a high-permittivity substrate has been built and tested. This oscillator antenna is a prototype for demonstrating the feasibility of such devices as compact, low-power-consumption building blocks of advanced, lightweight, phased antenna arrays that would generate steerable beams for communication and remotesensing applications.

Lee, Richard Q.; Miranda, Felix A.; Clark, Eric B.; Wilt, David M.; Mueller, Carl H.; Kory, Carol L.; Lambert, Kevin M.

2009-01-01

442

47 CFR 95.1213 - Antennas.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Antennas. 95.1213 Section 95.1213 Telecommunication...Radiocommunication Service (MedRadio) § 95.1213 Antennas. Except for the 2390-2400 MHz band, no antenna for a MedRadio transmitter shall be...

2013-10-01

443

47 CFR 78.105 - Antenna systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Antenna systems. 78.105 Section 78.105... Technical Regulations § 78.105 Antenna systems. (a) For fixed stations...Fixed CARS stations shall use directional antennas that meet the performance standards...

2010-10-01

444

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2011 CFR

... 5 2011-10-01 2011-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in a GMRS system and...

2011-10-01

445

Circular loop antenna for pattern steerable applications  

Microsoft Academic Search

A circular loop antenna with feed points on the loop is proposed. This antenna is envisaged to be useful for some beam steering applications. An example of this antenna with 8 feed points is analyzed. The eight feed points are placed symmetrically on the loop, which when excited one at a time steer the beam in eight different directions at

P. Deo; A. Mehta; D. Mirshekar-SyahkaI; P. J. Massey; H. Nakano

2009-01-01

446

47 CFR 95.51 - Antenna height.  

Code of Federal Regulations, 2014 CFR

... 5 2014-10-01 2014-10-01 false Antenna height. 95.51 Section 95.51 Telecommunication...General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in a GMRS system and...

2014-10-01

447

47 CFR 95.859 - Antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antennas. 95.859 Section 95.859 ...Technical Standards § 95.859 Antennas. (a) The overall height from ground to topmost tip of the CTS antenna shall not exceed the height...

2014-10-01

448

47 CFR 95.1213 - Antennas.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Antennas. 95.1213 Section 95.1213 Telecommunication...Radiocommunication Service (MedRadio) § 95.1213 Antennas. Except for the 2390-2400 MHz band, no antenna for a MedRadio transmitter shall be...

2014-10-01

449

Passive and active Reconfigurable antenna design  

E-print Network

Passive and active Reconfigurable antenna design Doctoral course ­ Ulm, Germany - October 8-12 2012 for reconfigurable antennas (Software defined radio; Cognitive radio; Other needs including defence and space surface mount, LTCC) - MMIC introduction and design flow - MMIC in antenna applications: system aspects

Pfeifer, Holger

450

Wireless link design using a patch antenna  

SciTech Connect

A wireless link was designed using a patch antenna. In the process, several different models were tested. Testing proved a patch antenna was a viable solution for building a wireless link within the design specifications. Also, this experimentation provided a basis for future patch antenna design.

Hall, E

2000-08-11

451

HANDSET ANTENNA DESIGN: PRACTICE AND THEORY  

Microsoft Academic Search

In this paper, an attempt is made to present a theory for the design of handset antennas, which results from the long experience that the authors have in the field of handset antenna design. The proposed theory is based on the well-known skin effect and constructs the antenna using a thin wire model that represent the backbone of the final

Wen Geyi; Qinjiang Rao; Shirook Ali; Dong Wang

2008-01-01

452

Integrated laptop antennas - design and evaluation  

Microsoft Academic Search

Two performance parameters are used to define integrated antennas for laptop applications. One is SWR, and another is the average antenna gain. Based upon link budget models and system requirements, the integrated antennas should have a 2:1 SWR bandwidth, wide enough to cover the 2.4 GHz ISM band to ensure a wireless system to have reliable, high data rate performance

Duixian Liu; Ephraim Flint; Brian Gaucher

2002-01-01

453

FPGA-Controlled Switch-Reconfigured Antenna  

Microsoft Academic Search

In this letter, p-i-n diodes are used as switches to connect and disconnect four patch sections to a midsection of a planar antenna. The antenna system is connected to the field programmable gate array (FPGA) board controlling the activation of these switches. The antenna with the incorporated diodes is designed, installed, and measured. The methodology for using an FPGA to

Severn Shelley; Joseph Costantine; Christos G. Christodoulou; Dimitris E. Anagnostou; James C. Lyke

2010-01-01

454

A novel 8 feed beam switched antenna  

Microsoft Academic Search

A novel double square loop (DSL) antenna for beam adaptive applications is proposed. The double square loop antenna consists of two identical square loops placed at 45deg to each other with a common centre. The antenna is fed at the eight external corners of the conductor loop arm, which when excited one at a time steer the beam through 360deg

A. Raaza; A. Mehta; D. Mirshekar-Syahkal; P. J. Massey

2008-01-01

455

Miniature UWB Antenna with Embedded Inductive Loading  

Microsoft Academic Search

Many commercial and military applications require small low profile UWB antennas that operate from 50 MHz to 2000 MHz. Using conventional designs to cover such a vast frequency range with a single antenna would require an aperture size and profile which are too large for practical applications. Antenna miniaturization techniques such as dielectric [1, 2] or reactive loading [3, 4

Brad A. Kramer; Ming Lee; Chi-Chih Chen; John L. Volakis

2006-01-01

456

Optimal surface adjustment of haystack antenna  

Microsoft Academic Search

A procedure has been developed for the optimal adjustment of the primary reflector surface of an antenna. This procedure, when applied to the haystack radio telescopic antenna, involves the iterative adjustment of standoffs and shear studs, expanders, and cable guide offsets in the back of the panels. Optimal adjustments are selected to minimize the resulting surface RMS of the antenna,

M. S. Zarghamee; J. Antebi

1992-01-01

457

Surface adjustment of modular mesh antenna  

Microsoft Academic Search

Mesh antennas have been selected as the main reflectors of large space antennas. The typical mesh antenna consists of metallic mesh shaped by a cable network and supporting structure. It is difficult to design the cable network because it is flexible. That is to say, the design parameters needed to achieve the desired cable network shapes are the tensions on

Masashi SHIMIZu

1994-01-01

458

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

459

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

460

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

461

Circularly polarized antennas with controlled radiation patterns  

Microsoft Academic Search

Log-helix conical antennas were examined as a way to satisfy the requirement for circular polarization of antennas for spacecraft use. It was concluded that a multiple-helix antenna which allows the helix lead angle to be changed can be used when the radiation and directivity in the direction of the reception point must be changed during flight.

B. A. Prigoda; V. A. Guryev; N. S. Ulyanin; N. N. Kalugin

1974-01-01

462

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

463

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

464

Miniature Multielement Antennas for Diversity Wireless Communications  

E-print Network

, having typical dimensions of RF MEMS switches, are appropriately located within the antenna structure at modifying its structure such that the new geometry, the qdime antenna, achieves better mutual coupling, has located in the antenna structure. Successively switching on a specific number of these elements allows

De Flaviis, Franco

465

Coupling element based mobile terminal antenna structures  

Microsoft Academic Search

In this paper, internal low-volume antenna structures for mobile terminals are studied. The work concentrates on the possibilities to reduce the volume of mobile terminal antenna elements by efficiently utilizing the radiation of the currents on the mobile terminal chassis. Essentially nonresonant coupling elements are used to optimally couple to the dominating characteristic wavemodes of the chassis. The antenna structures

Juha Villanen; Jani Ollikainen; Outi Kivekäs; Pertti Vainikainen

2006-01-01

466

COMPACT WIDEBAND TAG ANTENNA FOR UHF RFID  

E-print Network

. To get a physical operation of the proposed antenna, a simplified structure is presented and analyzed of the proposed tag antenna, we analyze and present an equivalent circuit model with a simplified structure structure and operation principle of the proposed antenna. Even though the structure does not have meander

Myung, Noh-Hoon

467

Investigation of proximity coupled antenna structures  

Microsoft Academic Search

Proximity coupled microstrip patch antennas (D.M. Pozar and B. Kaufman, Electron. Lett. vol. 23, no. 8, pp. 369-369, 1987) offer various advantages over conventional edge or probe fed patches. In this paper we investigate the standard proximity coupled printed antenna design and highlight the critical design parameters. We also present a stacked proximity coupled antenna, which achieves a broad bandwidth

W. S. T. Rowe; R. B. Waterhouse

2003-01-01

468

Optical Antenna Effect in Semiconducting Nanowires  

E-print Network

antenna is a linear structure. It receives and transmits polarized electromagnetic (EM) radiationOptical Antenna Effect in Semiconducting Nanowires G. Chen,,,§ Jian Wu,,§ Qiujie Lu,§ H. R with nanoscale antennae made from crystalline GaP nanowires (NWs). Using Raman scattering, we have observed

Xiong, Qihua

469

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

470

Circular polarisation characteristics of stacked microstrip antennas  

NASA Technical Reports Server (NTRS)

Experimental results on the circular polarization (CP) characteristics of a two-layer electromagnetically coupled (EMCP) antenna are presented. Compared to the single CP patch antenna, the two-layer EMCP antenna with proper spacings can provide better axial ratio and directivity.

Lee, R. Q.; Talty, T.; Lee, K. F.

1990-01-01

471

Coplanar waveguide feed for microstrip patch antennas  

NASA Technical Reports Server (NTRS)

A coplanar waveguide (CPW) loop is shown to be an effective low VSWR feed for microstrip antennas. The low VSWR transition between the CPW and the antenna is obtained without the use of a matching circuit, and it is relatively insensitive to the position of the antenna and the feed.

Smith, R. L.; Williams, J. T.

1992-01-01

472

Very small UWB antenna for WBAN applications  

Microsoft Academic Search

The increasing demand for lightweight and miniature size of Ultra-Wideband (UWB) applications in wireless communications such as Body Area Network (BAN), requires the design of very small UWB antennas. One of the main element of wireless body area network is an antenna, and there are numerous concerns to consider while designing an on-body antenna, including power consumption, size, frequency, required

Kamya Yekeh Yazdandoost; Kiyoshi Hamaguchi

2011-01-01

473

TPMS receive antenna design for large vehicles  

Microsoft Academic Search

TPMS (Tire Pressure Monitoring System) is becoming an industry standard for driving safety and fuel efficiency. The receiving antenna for TPMS resides in the near field of the sensor antenna and this makes it very difficult to establish a reliable RF link for large vehicles. In the design of receiving antenna, it is paramount to consider the electric field distribution

Anil Ozdemirli; M. Murat Bilgic; Korkut Yegin

2011-01-01

474

High Resolution Scanning Reflectarray Antenna  

NASA Technical Reports Server (NTRS)

The present invention provides a High Resolution Scanning Reflectarray Antenna (HRSRA) for the purpose of tracking ground terminals and space craft communication applications. The present invention provides an alternative to using gimbaled parabolic dish antennas and direct radiating phased arrays. When compared to a gimbaled parabolic dish, the HRSRA offers the advantages of vibration free steering without incurring appreciable cost or prime power penalties. In addition, it offers full beam steering at a fraction of the cost of direct radiating arrays and is more efficient.

Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

2000-01-01

475

Nested-cone transformer antenna  

DOEpatents

A plurality of conical transmission lines are concentrically nested to form n output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated.

Ekdahl, Carl A. (Santa Fe, NM)

1991-01-01

476

Microstrip Patch Antenna And Method  

NASA Technical Reports Server (NTRS)

Method and apparatus are provided for a microstrip feeder structure for supplying properly phased signals to each radiator element in a microstrip antenna array that may be utilized for radiating circularly polarized electromagnetic waves. In one disclosed embodiment. the microstrip feeder structure includes a plurality of microstrip sections many or all of which preferably have an electrical length substantially equal to one-quarter wavelength at the antenna operating frequency. The feeder structure provides a low loss feed structure that may be duplicated multiple times through a set of rotations and translations to provide a radiating array of the desired size.

Fink, Patrick W. (Inventor)

2001-01-01

477

Microstrip antenna developments at JPL  

NASA Technical Reports Server (NTRS)

The in-house development of microstrip antennas, initiated in 1981, when a spaceborne lightweight and low-profile planar array was needed for a satellite communication system, is described. The work described covers the prediction of finite-ground-plane effects by the geometric theory of diffraction, higher-order-mode circularly polarized circular patch antennas, circularly polarized microstrip arrays with linearly polarized elements, an impedance-matching teardrop-shaped probe feed, a dual-polarized microstrip array with high isolation and low cross-polarization, a planar microstrip Yagi array, a microstrip reflectarray, a Ka-band MMIC array, and a series-fed linear arrays.

Huang, John

1991-01-01

478

Nested-cone transformer antenna  

DOEpatents

A plurality of conical transmission lines are concentrically nested to form an output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated. 6 figures.

Ekdahl, C.A.

1991-05-28

479

Optimization of Antenna Structure Design  

NASA Technical Reports Server (NTRS)

Optimality criteria design is applied for large antenna structures with multiple constraints on microwave performance. The constraints are on accuracy of the structure: restrictions on the microwave pathlength error, and the antenna pointing error. The examples given show convergence to low-weight feasible designs that satisfy the constraints. Truss-member sizes are automatically selected from tables of commercially available structural shapes, and approximations results from the method of selection are found moderate. The multiple constraint design is shown to be more effective in meeting constraints than the old envelop method. For practical structures, the new design method can be performed within reasonable core size and computation time.

Levy, R.

1984-01-01

480

Interleaved array antenna technology development  

NASA Technical Reports Server (NTRS)

This is the third phase of a program to establish an antenna concept for shuttle and free flying spacecraft earth resources experiments using Synthetic Aperture Radar. The feasibility of a plated graphite epoxy waveguide for a space antenna was evaluated. A quantity of flat panels and waveguides were developed, procured, and tested for electrical and mechanical properties. In addition, processes for the assembly of a unique waveguide array were investigated. Finally, trades between various configurations that would allow elevation (range) electronic scanning and that would minimize feed complexity for various RF bandwidths were made.

1985-01-01

481

Antenna systems requirements definition study  

NASA Astrophysics Data System (ADS)

A plan to use a 55m wrap rib antenna in a second generation land mobile satellite service application as a specific mission to define a large space structure technology system and its interfaces is described. The system design aims to examine the launch phase of the mission including interface with the space transportation system and the orbital transfer vehicle, and the deployment from the spacecraft of the boom, antennas, and solar panels. Methods for determining the effect of system configuration on the interfaces and of the space environment and operational events on the system and its subsystem interfaces are discussed.

Golden, C. T.

1981-02-01

482

Doubled Conformal Compactification  

E-print Network

We use Weyl transformations between the Minkowski spacetime and dS/AdS spacetime to show that one cannot well define the electrodynamics globally on the ordinary conformal compactification of the Minkowski spacetime (or dS/AdS spacetime), where the electromagnetic field has a sign factor (and thus is discountinuous) at the light cone. This problem is intuitively and clearly shown by the Penrose diagrams, from which one may find the remedy without too much difficulty. We use the Minkowski and dS spacetimes together to cover the compactified space, which in fact leads to the doubled conformal compactification. On this doubled conformal compactification, we obtain the globally well-defined electrodynamics.

Zhao Yong Sun; Yu Tian

2014-10-16

483

Compact conformal manifolds  

NASA Astrophysics Data System (ADS)

In this note we begin a systematic study of compact conformal manifolds of SCFTs in four dimensions (our notion of compactness is with respect to the topology induced by the Zamolodchikov metric). Supersymmetry guarantees that such manifolds are Kähler, and so the simplest possible non-trivial compact conformal manifold in this set of geometries is a complex one-dimensional projective space. We show that such a manifold is indeed realized and give a general prescription for constructing complex N-dimensional projective space conformal manifolds as certain small breaking deformations of strongly interacting SCFTs. In many cases, our prescription reduces the construction of such spaces to a study of the chiral ring. We also give an algorithm for constructing more general compact spaces of SCFTs.

Buican, Matthew; Nishinaka, Takahiro

2015-01-01

484

Compact Conformal Manifolds  

E-print Network

In this note we begin a systematic study of compact conformal manifolds of SCFTs in four dimensions (our notion of compactness is with respect to the topology induced by the Zamolodchikov metric). Supersymmetry guarantees that such manifolds are Kahler, and so the simplest possible non-trivial compact conformal manifold in this set of geometries is a complex one-dimensional projective space. We show that such a manifold is indeed realized and give a general prescription for constructing complex N-dimensional projective space conformal manifolds as certain small N=2->N=1 breaking deformations of strongly interacting N=2 SCFTs. In many cases, our prescription reduces the construction of such spaces to a study of the N=2 chiral ring. We also give an algorithm for constructing more general compact spaces of SCFTs.

Matthew Buican; Takahiro Nishinaka

2014-11-14

485

Conformal symmetry and unification  

SciTech Connect

The Weyl-Weinberg-Salam model is presented. It is based on the local conformal gauge symmetry. The model identifies the Higgs scalar field in SM with the Penrose-Chernikov-Tagirov scalar field of the conformal theory of gravity. Higgs mechanism for generation of particle masses is replaced by the originated in Weyl's ideas conformal gauge scale fixing. Scalar field is no longer a dynamical field of the model and does not lead to quantum particle-like excitations that could be observed in HE experiments. Cosmological constant is naturally generated by the scalar quadric term. Weyl vector bosons can be present in the theory and can mix with photon--Z-boson system.

Pawlowski, Marek [Soltan Institute for Nuclear Studies, Warsaw (Poland)

1998-12-15

486

Conformal Random Geometry  

E-print Network

In these Notes, a comprehensive description of the universal fractal geometry of conformally-invariant scaling curves or interfaces, in the plane or half-plane, is given. The present approach focuses on deriving critical exponents associated with interacting random paths, by exploiting their underlying quantum gravity structure. The latter relates exponents in the plane to those on a random lattice, i.e., in a fluctuating metric, using the so-called Knizhnik, Polyakov and Zamolodchikov (KPZ) map. This is accomplished within the framework of random matrix theory and conformal field theory, with applications to geometrical critical models, like Brownian paths, self-avoiding walks, percolation, and more generally, the O(N) or Q-state Potts models and, last but not least, Schramm's Stochastic Loewner Evolution (SLE_kappa). These Notes can be considered as complementary to those by Wendelin Werner (2006 Fields Medalist!), ``Some Recent Aspects of Random Conformally Invariant Systems,'' arXiv:math.PR/0511268.

Bertrand Duplantier

2006-08-23

487

Conformal General Relativity  

E-print Network

The inflation-free solution of problems of the modern cosmology (horizon, cosmic initial data, Planck era, arrow of time, singularity,homogeneity, and so on) is considered in the conformal-invariant unified theory given in the space with geometry of similarity where we can measure only the conformal-invariant ratio of all quantities. Conformal General Relativity is defined as the $SU_c(3)\\times SU(2)\\times U(1)$-Standard Model where the dimensional parameter in the Higgs potential is replaced by a dilaton scalar field described by the negative Penrose-Chernikov-Tagirov action. Spontaneous SU(2) symmetry breaking is made on the level of the conformal-invariant angle of the dilaton-Higgs mixing, and it allows us to keep the structure of Einstein's theory with the equivalence principle. We show that the lowest order of the linearized equations of motion solves the problems mentioned above and describes the Cold Universe Scenario with the constant temperature T and z-history of all masses with respect to an observable conformal time. A new fact is the intensive cosmic creation of $W,Z$-vector bosons due to their mass singularity. In the rigid state, this effect is determined by the integral of motion $(m_w^2H_{\\rm hubble})^{1/3}=2.7 K k_B$ that coincides with the CMB temperature and has the meaning of the primordial Hubble parameter. The created bosons are enough to consider their decay as an origin of the CMB radiation and all observational matter with the observational element abundances and the baryon asymmetry. Recent Supernova data on the relation between the luminosity distance and redshift (including the point $z=1.7$) do not contradict the dominance of the rigid state of the dark matter in the Conformal Cosmology.

V. Pervushin; D. Proskurin

2001-06-03

488

Boundary Conformal Field Theory  

E-print Network

Boundary conformal field theory (BCFT) is simply the study of conformal field theory (CFT) in domains with a boundary. It gains its significance because, in some ways, it is mathematically simpler: the algebraic and geometric structures of CFT appear in a more straightforward manner; and because it has important applications: in string theory in the physics of open strings and D-branes, and in condensed matter physics in boundary critical behavior and quantum impurity models. In this article, however, I describe the basic ideas from the point of view of quantum field theory, without regard to particular applications nor to any deeper mathematical formulations.

John Cardy

2008-02-20

489

Charged conformal Killing spinors  

NASA Astrophysics Data System (ADS)

We study the twistor equation on pseudo-Riemannian Spinc-manifolds whose solutions we call charged conformal Killing spinors (CCKSs). We derive several integrability conditions for the existence of CCKS and study their relations to spinor bilinears. A construction principle for Lorentzian manifolds admitting CCKS with nontrivial charge starting from CR-geometry is presented. We obtain a partial classification result in the Lorentzian case under the additional assumption that the associated Dirac current is normal conformal and complete the classification of manifolds admitting CCKS in all dimensions and signatures ?5 which has recently been initiated in the study of supersymmetric field theories on curved space.

Lischewski, Andree

2015-01-01

490

Nanorod optical antennas for dipolar transitions  

E-print Network

Optical antennas link objects to light. Here, we analyze metal nanorod antennas as cavities with variable reflection coefficients to derive the interaction of dipolar transitions with radiation through the antenna modes. The presented analytical model accurately describes the complete emission process, and is summarized in a phase-matching equation. We show how antenna modes evolve as they become increasingly more bound, i.e. plasmonic. The results illustrate why efficient antennas should not be too plasmonic, and how subradiant even modes can evolve into weakly-interacting dark modes. Our description is valid for the interaction of nanorods with light in general, and is thus widely applicable.

Tim H. Taminiau; Fernando D. Stefani; Niek F. van Hulst

2009-12-10

491

Phased array antenna for space shuttle orbiter  

NASA Astrophysics Data System (ADS)

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 consists of an eight-element transmit section, eight-element receive section, and a single L-band receive element. The antenna design is constrained by the existing Orbiter system and space environment. The solution to the interface design problems led to an antenna system which provides improved link margins and yet supports previous operational configurations. This paper describes the system development, antenna hardware, and the interface consideration which led to the final design.

Davidson, Shayla E.

1987-02-01

492

Error margin for antenna gain measurements  

NASA Technical Reports Server (NTRS)

The specification of measured antenna gain is incomplete without knowing the error of the measurement. Also, unless gain is measured many times for a single antenna or over many identical antennas, the uncertainty or error in a single measurement is only an estimate. In this paper, we will examine in detail a typical error budget for common antenna gain measurements. We will also compute the gain uncertainty for a specific UHF horn test that was recently performed on the Jet Propulsion Laboratory (JPL) antenna range. The paper concludes with comments on these results and how they compare with the 'unofficial' JPL range standard of +/- ?.

Cable, V.

2002-01-01

493

Galilean conformal and superconformal symmetries  

SciTech Connect

Firstly we discuss briefly three different algebras named as nonrelativistic (NR) conformal: Schroedinger, Galilean conformal, and infinite algebra of local NR conformal isometries. Further we shall consider in some detail Galilean conformal algebra (GCA) obtained in the limit c{yields}{infinity} from relativistic conformal algebraO(d+1, 2) (d-number of space dimensions). Two different contraction limits providing GCA and some recently considered realizations will be briefly discussed. Finally by considering NR contraction of D = 4 superconformal algebra the Galilei conformal superalgebra (GCSA) is obtained, in the formulation using complexWeyl supercharges.

Lukierski, J., E-mail: lukier@ift.uni.wroc.pl [University of Wroclaw, Institute for Theoretical Physics (Poland)

2012-10-15

494

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 3223 Conformal Magnetic Composite RFID for Wearable  

E-print Network

for flexible miniaturized RF identification (RFID) tags has rapidly increased due to the requirements Magnetic Composite RFID for Wearable RF and Bio-Monitoring Applications Li Yang, Student Member, IEEE, Lara magnetic composite material for RF identification (RFID) and wearable RF antennas. First, one conformal

Tentzeris, Manos

495

DSS 13 microprocessor antenna controller  

NASA Technical Reports Server (NTRS)

A microprocessor-based antenna monitor and control system with multiple CPUs are described. The system was developed as part of the unattended station project for DSS 13 and was enhanced for use by the SETI project. The operational features, hardware, and software designs are described, and a discussion is provided of the major problems encountered.

Gosline, R. M.

1988-01-01

496

Trislot-cavity microstrip antenna  

NASA Technical Reports Server (NTRS)

Flush-mountable assembly composed of disk radiator sandwiched between planes of metal-clad dielectric board has greater bandwidths and beamwidths than simple disk antenna. Conducting planes connect so that disk is enclosed in cavity with Y-shaped slot in top plane. Cavity is excited by microwave energy from disk and radiates from trislot aperature.

Ellis, H., Jr.

1981-01-01

497

Fundamental Limitations of Small Antennas  

Microsoft Academic Search

A capacitor or inductor operating as a small antenna is theoretically capable of intercepting a certain amount of power, independent of its size, on the assumption of tuning without circuit loss. The practical efficiency relative to this ideal is limited by the \\

H. A. Wheeler

1947-01-01

498

Aircraft Antenna System Lightning Protection  

Microsoft Academic Search

The recent use of insulated aircraft wing or fin cap sections for radio antennas has required that consideration be given not only to the protection of radio equipment but to the protection of the insulated aircraft sections as well. Failure of simple spark gap protection used in early installations for aircraft radio equipment has been correlated to the occurrence of

R. F. Huber; M. M. Newman; J. D. Robb

1955-01-01

499

Microstrip antenna theory and design  

Microsoft Academic Search

Microstrip is the name given to a type of open waveguiding structure which is now commonly used in present-day electronics, not only as a transmission line but for circuit components such as filters, couplers, and resonators. The idea of using microstrip to construct antennas is a much more recent development. The purpose of this monograph is to present the reader

J. R. James; P. S. Hall; C. Wood

1981-01-01

500

Two-Arm Sinuous Antennas  

Microsoft Academic Search

Two-arm sinuous antennas are introduced in this paper. The proposed configurations and realized phase progressions result in a unique multiband behavior with alternating polarization handedness between adjacent bands. Two sinuous embodiments are presented: a planar, cavity backed, flush mountable design and a unidirectional, conically projected structure. Both designs exhibit multiband and multipolarized performance with low axial ratio and good pattern

Michael C. Buck; Dejan S. Filipovic ´

2008-01-01