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20050169653 Paderborn Univ., Germany Broadband, Dual Polarised Microstrip Antennas with Improved Beam Forming and Gain Capabilities Schwenzfeier, Eva; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 120-123; In English; See also 20050169565; Copyright; Avail: Other Sources Proximity-coupled antennas like microstrip antennas in general exhibit only a small bandwidth. Different attempts have been made to increase the bandwidth of microstrip antennas, including the use of thicker substrates, of parasitic elements and of impedance-matching networks. Although the bandwidth may be increased for the reception of one polarisation, the results achieved in prior art are not sufficient for DTH (Direct-To-Home) satellite reception. Adual polarised antenna is required from 10.70GHz to 12.75 GHz (relative bandwidth 17.5%). Extensive research in our department led to a special kind of broadband proximity-coupled and dual polarised antenna. This two-layers configuration is characterized by a simple structure. Based on this antenna, two novel microstrip antennas were developed which additionally guarantee beam forming and increase gain. These improved antennas are suitable in antenna arrays to reduce the number of elements and to simplify the feeding network. Another more often used DTH reception unit is a combination of a parabolic reflector, a feedhorn and a LNB (Low Noise Block Converter). As illustrated in, it is preferable to avoid the transition loss from hollow waveguide, i.e. the feedhorn, to planar waveguide technology, i.e. the LNB, by replacing the feedhorn with a single microstrip antenna. An improvement of beam forming hence is very important for the illumination of the reflector. Therefore, the two novel antenna elements are the main issue of this contribution. Author Broadband; Polarized Electromagnetic Radiation; Microstrip Antennas; Beamforming 20050169659 Chan Technologies, Inc., Kirkland, Quebec, Canada A Circularly Polarized Waveguide Array for LEO Satellite Communications Chan, K. K.; Marcoux, F.; Forest, M.; Martins-Camelo, L.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 154-157; In English; See also 20050169565; Copyright; Avail: Other Sources The development of a low profiled, circularly polarized waveguide array for LEO satellite communications is presented. Due to the large quantities of spacecraft forming the LEO constellation, the design of such an array requires a low cost approach. The array operates from 12.95 to 14.50 GHz and is designed to have an active match of better than 25 dB across the band. The array is fed by a compact reactive waveguide beamforming network, which dictates the need for well-matched radiating elements. To provide beam zooming capability, the element excitations are controlled to generate different orbit location dependent beams. Circular polarization is achieved by means of a meander-linpolarizer. Design and test of this antenna are discussed in the following sections. Author Waveguides; Circular Polarization; Arrays; Low Earth Orbits; Satellite Communication 20050169666 Queensland Univ., Saint Lucia, Australia Development and Performance of an L-Band Phased Antenna for Mobile Satellite Communications Karmakar,N. C.; Bialkowski, M. E.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 158-161; In English; See also 20050169565; Copyright; Avail: Other Sources Recent years have witnessed an introduction of a large number of mobile satellite (MSS) communications systems. These include a global GEO MSS system,inmarsat, and domestic GEO MSS systems such as North-American AMSC, Japan’s N-Star and the Australian Mobilesat. At present, two types of antennas can be used to access GEO MSS services. They include: (1) fixed position antennas, which are used with portable transceivers, and (2) fully mobile antennas such as those installed on a land vehicle.The fixed position antennas arerelativelyeasytodesign,astheyhave to meet a moderate (approximately7%) operational bandwidth and a medium (about 10dBi) gain. There are a number of complete portable systems in the commercial market that include both a transceiver and an antenna. One inconvenience of portable systems is that they require the user be stationary with respect to the ground. This inconvenience can be overcome with a mobile antenna system. The design of such a system is more challenging as new features associated with mobility have to be incorporated. This paper presents the development and performance of a circular phased array antenna for land-vehicle mobile satellite communications. This antenna is specifically aimed for use with the Australian MSS, Mobilesat. However, it can easily be modified for use with the other L-band GEO MSS systems. Author Antenna Design; Performance Prediction; Mobile Communication Systems; Satellite Communication 55 20050169668 Northwestern Univ., Evanston, IL, USA A Dual-Band Antenna for Cellular Applications: Influence of Plastic Embedding Vasilyeva, Elena; Taflove, Allen; Navsariwala, Umesh; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 108-111; In English; See also 20050169565; Copyright; Avail: Other Sources With an increasing demand for cellular phones operating at two frequency bands, several new antenna designs have been proposed. Recently, a dual-band (GSM and DCS) antenna design using three elements with one feed point was proposed. For the elements not clad by plastic, the radiation patterns were shown to be basically omnidirectional (though maximum radiation directions were not in the horizontal plane), and the antenna was tunable by adjusting the length of the wire elements. In this paper, we report FDTD modeling results for a practical situation wherein the wire elements are formed in a plastic rod. Our modeling study indicates a large shift of the antenna’s radiation pattern in the elevation plane. This shift likely negates the usefulness of the design. Author Antenna Design; Cladding; Plastics; Electrical Insulation 20050169669 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, USA A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band Kelly, Kenneth C.; Huang, John; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 162-165; In English; See also 20050169565; Copyright; Avail: Other Sources A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L-Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design. Author Polarization (Waves); Microstrip Antennas; Antenna Design; Imaging Techniques 20050169675 University of Central Florida, Orlando, FL, USA A High Efficiency L-Band Microstrip Antenna Faiz, M. M.; Wahid, P. F.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 272-275; In English; See also 20050169565; Copyright; Avail: Other Sources The design of a high efficiency circularly polarized neatly square patch antenna at the L-band is presented. One way to improve the efficiency of the inherently low efficiency microstrip antennas is to use substrates with a low permittivity. A low permittivity substrate with epsilon = 1.1028 was obtained by using a combination of Rogers RT/Duroid 5880 and Rohacell hard foam. The effect ofa 5 mils thick Rogers RT/Duroid 5880 superstrate on the efficiency was also studied. Results of the antenna efficiency and bandwidth for both the low dielectric substrate and superstrate are presented. The results were obtained using the IE3D software package and compared with measured results. Efficiencies of the order of 85% for a single patch element were obtained. Author Ultrahigh Frequencies; Microstrip Antennas; Patch Antennas; Substrates; Permittivity 20050169676 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, USA A Dual-polarized Microstrip Subarray Antenna for an Inflatable L-band Synthetic Aperture Radar Zawadzki, Mark; Huang, John; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 276-279; In English; See also 20050169565; Copyright; Avail: Other Sources Inflatable technology has been identified as a potential solution to the problem of achieving small mass, high packaging 56 efficiency, and reliable deployment for future NASA spaceborne synthetic aperture radar (SAR) antennas. Presently, there exists a requirement for a dual-polarized L-band SAR antenna with an aperture size of 10m x 3m, a center frequency of 1.25GHz, a bandwidth of 80MHz, electronic beam scanning, and a mass of less than 100kg. The work presented below is part of the ongoing effort to develop such an inflatable antenna array. Author Microstrip Antennas; Antenna Arrays; Inflatable Space Structures; Large Space Structures; Space Based Radar 20050169677 Nippon Electric Co. Ltd., Yokohama, Japan 180 deg/alpha deg Combined Phase Shifter Nakada, Kuniyoshi; Murumoto, Tsunehisa; Iwata, Ryuichi; IEEEAntennas and Propagation Society International Symposium, Volume 1; [1999], pp. 218-221; In English; See also 20050169565; Copyright; Avail: Other Sources Strip line phase shiflers are key devices widely used in phased array antenna application. To avoid the grating-lobes through a wide range of scanning angle, the element spacing in the array should be less than about lambda/2. In order to arrange all of the phase shifters in the phased array antenna on a single plane, each phase shifter should be as compact as possible. The digital phase shifter, composed of cascaded several bit elements (180 deg, 90 deg, 45 deg, 22.5 deg, ), is widely used for phased array application. For the elements smaller than 90 deg bit, the loaded-line phase shifters are generally used because of low insertion loss and simplicity. However, using the loaded-line phase shifter, 180 deg phase shift cannot be obtained in principle. Thus, for the element of 180 deg bit, the switched-line phase shifter is widely used, though it has disadvantage of its large size and large phase shift deviation within a bandwidth. In this paper, we propose 180 deg/alpha deg Combined Phase Shifter, which consists of 180 deg switched-line section and arbitrary angle (alpha deg) loaded-line section. This proposed phase shifter operates as a 2-bit phase shifter, and has both physical and electrical advantages, i.e., its compact size and small phase shift deviation. This paper presents basic configuration of the proposed phase shifter, and also presents an example of characteristics in the case of alpha deg = 45 deg calculated by Method of Moment. Author Phased Arrays; Antenna Arrays; Phase Shift Circuits 20050169682 Illinois Univ., Urbana, IL, USA Full Wave Analysis of Microstrip Lines on Anisotropic Inhomogeneous Substrates Radhakrishnan, Kaladhar; Chew, Weng Cho; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 230-233; In English; See also 20050169565 Contract(s)/Grant(s): F49620-96-1-0025; N00014-95-1-0872; NSF ECS-93-02145; Copyright; Avail: Other Sources Recent developments in microwave integrated circuits have led to complex waveguiding structures with multiple conductors on inhomogeneous substrate which may or may not be anisotropic Several techniques are available for the analysis of microstrip lines. A generalized technique to study microstrip lines should be able to account for anisotropy in the substrate. Anisotropy may occur naturally in the substrate or may be artificially induced to improve system performance In this paper, we use the finite difference formulation to model the microstrip line. The wave equation involving the transverse field components is discretized resulting in a sparse eigenvalue problem A spatial interpolation scheme is used to evaluate the contribution from the off-diagonal terms in the permittivity and permeability tensors. It is shown that the two-term interpolation scheme performs just as well as the more common four-term scheme. Direct spectral decomposition of the matrix is expensive for complicated waveguiding structures with large matrices. However, by exploiting the sparsity of the matrices, it is possible to solve for the eigenpairs much more efficiently. This is accomplished using the bi-Lanczos algorithm. Author Microstrip Transmission Lines; Anisotropy; Wave Equations; Homogenizing; Substrates 20050169686 Arizona State Univ., Tempe, AZ, USA Analysis of HF Antennas on a Helicopter in the Presence of a Stratified Ground Han, Dong-Ho; Polycarpou, Anastasis C.; Balanis, Constantine A.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 496-499; In English; See also 20050169565; Copyright; Avail: Other Sources Analysis of antennas on a helicopter airframe including the surrounding environment, such as the ground, will provide much more reliable radiation characteristics for communication rink budget predictions. In order to account for all reflections and diffractions from the airframe, as well as those from a stratified ground, a full-wave analysis should be used. Since the exact Green’s function for a stratified ground is available, the radiation problem of a helicopter above the ground reduces to a problem of finding the total equivalent source in the presence of the ground. Furthermore, if the observation points are 57 confined only in the upper hemisphere, then the asymptotic solution for the radiated field due to the source can be obtained by using the Reflection Coefficient Method (RCM) or Norton’s approximation. In this paper, HF antennas, such as a 14-ft towel-bar and a 24-ft inverted-L on the AH-64 (Apache) full-scale helicopter, are analyzed in the presence of a stratified ground. In particular, the ground influence on the radiation pattern is investigated using the Finite Element Method (FEM) in conjunction with Norton’s approximation. Therefore, the radiated field contains not only the space wave but also the surface wave which is important for a short observation distance. The lossy ground is defined by its relative permittivity and electric conductivity. Derived from text High Frequencies; Antenna Design; Airframes; Stratification; AH-64 Helicopter 20050169688 Cheng-Shiu Univ., Taiwan Inset-Microstrip-Fed Circularly Polarized Microstrip Antennas Chen, Wen-Shyang; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 260-263; In English; See also 20050169565; Copyright; Avail: Other Sources An inset-microstripline-fed microstrip antenna, due to its advantage of one printed step without external matching network and coplanar design in single-layer substrate, has widely used in integration with other microwave elements and array design. Most of related designs only using an inset-microstripline feed for achieving linear polarization operation have been reported. Here, we will first demonstrate novel design of inset-microstripline-fed circularly-polarized microstrip antenna from corner-truncated patch with an inserted slit. A 50 Ohm matching microstripline is introduced and directly inset to the modified square microstrip antenna for circular polarization (CP) operation. And, by using much more slits inserted at the comer-truncated patch boundary, these inserted slits can result in meandering of the excited fundamental-mode patch surface current path, which effectively lowers the resonant frequency of the modified square patch, similar to the design using four inserted slits of different lengths at the boundary of a square patch. Results have been obtained that a compact CP operation for the modified design can be achieved by using an inset microstripline feed. Details of design of inset-microstripline-fed microstrip antennas are discussed in the Symposium. Author Microstrip Antennas; Planar Structures; Circular Polarization 20050169689 National Kaohsiung Inst. of Marine Technology, Koahsiung, Taiwan, Province of China Single-Feed Circularly Polarized Triangular Microstrip Antennas Lu, Jui-Han; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 264-267; In English; See also 20050169565; Copyright; Avail: Other Sources Recently, many designs of single-feed circularly polarized microstrip antennas with square or circular patches have been reported. It is found that, for both regular-size and compact CP operations, the related designs of microstrip antennas are largely on square and circular patches. Relatively very few designs for achieving CP operation using triangular microstrip antennas are available in the open literature. This motivates the present study of novel designs of both regular-size and compact CP operations of triangular microstrip antennas. For the present, the typical designs of circularly polarized triangular microstrip antennas that have been reported are the designs using a nearly equilateral-triangular patch or an equilateral- triangular patch with a slit inserted at the patch edge. In this article, we first demonstrate another promising regular-size CP design of triangular microstrip antennas with an embedded narrow horizontal slot. And, it is then shown that, by using a cross slot of unequal slot lengths in place of the embedded horizontal slot, the circularly polarized radiation of the slotted triangular microstrip antenna can occur at a lower operating frequency. Details of the proposed CP designs of slotted triangular microstrip antennas are described, and experimental results of the CP performance are presented and discussed. Author Circular Polarization; Triangulation; Microstrip Antennas 20050169690 Saitama Univ., Urawa, Japan Array Antenna Composed of Circularly Polarized Dielectric Resonator Antennas Haneishi, Misao; Wu, Bing; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 252-255; In English; See also 20050169565; Copyright; Avail: Other Sources Recently, a dieleclric resonator antenna (DRA) including circularly polarized DRA (CP-DRA) has been studied by many researchers, since it can be used as an efficient radiator in the high frequency region. A new type of CP-DRA element fed by an asymmetric cross-slot is proposed here. This type of CP-DRA is probably one of the simplest device for producing circular 58 polarization at or near the millimeter-wave region. This paper presents the radiation properties of a new type of CP-DRA element together with the design technique of DRA array composed of a pair of CP-DRAs. In order to evaluate the performance, some DRA elements and its arrays were fabricated and tested at X-band. The 3-dB axial-ratio bandwidth obtained from this new type of DRA array was about 20% at X-band, and it had an extremely broadband performance compared to that of an usual array antenna. Therefore, the DRA array proposed here is considered to be an effective model as a broadband circularly polarized array. Author Antenna Arrays; Resonators; Circular Polarization 20050169691 Centre National de la Recherche Scientifique, Valbonne, France Array of Coupled Oscillators Generating Circular Polarization Dussopt, L.; Laheurte, J-M.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 268-271; In English; See also 20050169565; Copyright; Avail: Other Sources Coupled-oscillator arrays have been widely used for linear polarization but have not been implemented in communication systems involving circular polarization. This paper presents an array of four coupled oscillators using linearly polarized elements to generate circular polarization (CP). An array to generate CP with linearly polarized elements has been extensively described. The array consists in four patch elements with 0 deg, 90 deg, 180 deg, 270 deg arrangement both for angular orientation and feed phase. This array has shown good CP quality for a wide axial ratio bandwidth. The coupling circuit is designed so that a 0 deg, 90 deg, 180 deg, 270 deg arrangement for the oscillator phases is obtained. Since stable steady-state operation can not be achieved for this phase arrangement with classical mutual coupling, the oscillators are phase-locked in a loop by unidirectional coupling provided by amplifiers. This new arrangement is theoretically investigated and validated by measurements of CP radiation patterns. Author Oscillators; Arrays; Circular Polarization; Antenna Components 20050169692 Cheng-Shiu Univ., Taiwan Small Circularly Polarized Microstrip Antennas Chen, Wen-Shyang; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 256-259; In English; See also 20050169565; Copyright; Avail: Other Sources For satisfying requirement of compactness, the related designs with circularly polarized radiation have been reported. In these designs, a modification element for achieving a compact circular polarization (CP) operation is introduced by using a cross-slot cut in the circular microstrip patch center or two pairs of narrow slots inset at the boundary of the square microstrip patch. It can be noted that these CP designs are used by a cross slot or two pairs narrow slot of owing unequal length to split the antenna’s fundamental mode into two near-degenerate resonant modes with equal amplitude and 90 deg. phase difference. In practical application, this makes it possible to be less freedom degree of fabrication. It is inconvenient to carry out post-manufacturing free-tuning in such designs to compensate for the possible fabrication errors and substrate material tolerances. Here, we demonstrate two configuration to perform the small CP operation with much relaxed manufacturing tolerances. One is a peripheral-cuts circular microstrip antenna with a equal arm-length cross slot, and the other is a comer-truncated square microstrip antenna with four equal arm-length bent slots. With the peripheral cuts or truncated corners in the microstrip patch, it can be splitted antenna’s fundamental mode into two near degenerate orthogonal modes with quadrature phases. Also with a equal arm-length cross slot or four equal ann-length bent slots embedded in the microstrip patch, the proposed microstfip antenna is expected to lengthen their two near degenerate orthogonal modes as compared to the peripheral-cuts circular microstrip antenna or corner-truncated square microstrip antenna. Typical results of the proposed design for the small CP antennas will be discussed in the Symposium. Author Microstrip Antennas; Polarized Radiation; Design Analysis; Void Ratio 20050169701 Da-Yeh Univ., Taiwan Cylindrical and Rectilinear Microstrip Lines with Indented Grounds Hsu, Chung-I G.; Kiang, Jean-Fu; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 322-325; In English; See also 20050169565; Copyright; Avail: Other Sources Microstrip lines have been the most popular interconnects between microwave devices. Results and applications of various microstrip structures that are rectilinear in nature can be found in the literature, for example). Wedge-supported 59 microstrip structures are widely utilized in the conformal antenna system constructed in aircraft and missiles. The analysis in does not allow the presence of the superstrate. The structures considered in are restricted to the case where conducting strips are printed on the surface of the single-layered substrate. Broadside-coupled microstrip structures cannot be tackled in. Also, the outer shielding conductors are not considered in beth and. In this research, we will extend the mode-matching technique developed in to handle the structure that consists of a multilayered background medium, optional inner and/or outer shielding conductors, and indents or cavities on the shielding conductors. The indents are usually due to undesired surface imperfection in the fabrication process, whereas the cavities can be used to provide additional degrees of freedom in designing a transmission-lin.e system. Derived from text Microstrip Transmission Lines; Cylindrical Bodies; Microwave Equipment 20050169703 National Taiwan Univ., Taipei, Taiwan, Province of China Antenna Gain and Scattering Measurement Using Reflective Three-Antenna Method Lu, Hsin-Chia; Chu, Tah-Hsiung; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 374-377; In English; See also 20050169565; Copyright; Avail: Other Sources Three-antenna method is a technique to measure the antenna gain without using a reference antenna. Since it operates in a transmission-type arrangement, a long return cable is required. Several methods were then developed to eliminate the return cable by using the radar cross section (RCS) measurement method. The advantages of this method are described. A measurement method based on RCS measurement concept and antenna scattering matrix is developed. It can not only measure the antenna gain, but also derive the structural scattering characteristics and antenna input impedance from the measurement. However, it requires a complicated polarimetric calibration procedure for the measurement system. In this paper, a novel method is proposed to combine the concepts of three-antenna method and RCS measurement method to measure the antenna gain and its structural scattering characteristics without involving the reference antenna or polarimetric calibration. In this method, the measurement arrangement including the transmitting and receiving antennas is considered as a two-port network with reference planes at the input port for each antenna as shown. By connecting three different known terminators at the receiving antenna port and measure the reflection coefficients at the transmitting antenna port, the scattering parameters of this two-port network can be derived. They are shown to be related to the product of two antennas’ gain. Therefore one can follow the three-antenna method to find the gain of each antenna. In addition, the structural scattering characteristics of each antenna can be solved. Derived from text Antenna Gain; Reflectance; S Matrix Theory; Antenna Design 20050169707 Alexandria Univ., Egypt Frequency Hopped-Chirp Modulation (FH-CM) for Multi-User Signaling in Multipath Dispersive Media El-Khamy, Said E.; Shaaban, Shawki E.; Thabet, Essam A.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 396-399; In English; See also 20050169565; Copyright; Avail: Other Sources Chirp signals are categorized as spread-spectrum signals and have good advantages in interference rejection. The use of matched chirp modulation (MCM) for efficient digital signaling in dispersive communication channels has also been considered by E1-Khamy et al. Chirp modulation has also been considered for multi-user applications. New forms of multi-user chirp modulation (M-CM) signals that are characterized by the same power as well as the same bandwidth have been introduced recently by the authors. In this paper, we investigate the combination of frequency-hopping (FH) spread-spectrum techniques with M-CM to produce a multiple-access technique that is characterized by good performance in dispersive and fading propagation media. The considered frequency-hopped chirp modulation (FH-CM) is investigated in details and its performance is shown to highly outperform that of M-CM. Derived from text Chirp Signals; Frequency Hopping; Modulation; Multipath Transmission; Mathematical Models 20050169710 California Univ., Los Angeles, CA, USA Optimal Design of the Generalized Three-Parameter Aperture Distribution by the Emperor-Selective Genetic Algorithm Lu, Yilong; Rahmat-Samii, Yahya; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 422-425; In English; See also 20050169565; Copyright; Avail: Other Sources This paper presents a novel approach for automatic design of optimal aperture field distribution based on the versatile 60 three-parameter (3-P) model for elliptical (or circular) aperture antennas. This model is very useful for the design of aperture type antennas such as reflector antennas, lenses, and large planar arrays. In application, the challenge is how to find those parameters to give the optimal aperture distribution so as to achieve the desired radiation characteristics of aperture antennas. For example, one may desire high directivity, low sidelobe level (SLL), high beam efficiency, and low spillover for a shaped reflector antenna. In order to make the best use of the 3-P model for optimal design of aperture distribution, the Emperor-Selective based genetic algorithm (EMS-GA) is used to find the three parameters. Genetic Algorithms (GAs) are scholastic optimization technique based on the concept of biological genetics and natural selection and they have a very wide application in optimization of engineering problems. However, the standard GAs, which based on randomized-mating and binary-crossover, suffer from one major drawback and they are usually unable to move the search to areas outside the space of the initial population. In our GA, the more effective Emperor-Selective (EMS) mating scheme and floating number interpolating and extrapolating linear crossover are used for fast solutions. Simulations show that only a few generations may be used to achieve satisfactory results. Author Apertures; Distribution Functions; Genetic Algorithms; Design Analysis 20050169711 Nebraska Univ., Lincoln, NE, USA Stationary Solutions for the Rough Surface Radar Backscatter Cross Sections Based on a Two Scale Full Wave Approach Bahar, Ezekiel; Crittenden, Paul; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 510-513; In English; See also 20050169565; Copyright; Avail: Other Sources Using a full wave approach, the rough surface radar backscatter cross sections are expressed as weighted sums of two cross sections. Tile radar cross sections associated with the larger scale surface are reduced by a factor equal to the square of tile characteristic function of the smaller scale surface (that rides upon the larger scale surface). The Bragg scatter contributions front the small scale surface are modulated by the slopo_ of the large scale surface. The back scatter cross sections are obtained by regarding the rough surface as an ensemble of patches of random rough surfaces with arbitrary orientations. It. is shown that the full wave solutions are stationary over a wide range of patch sizes. The patches are characterized by tile spectral wavenumber that separates the large scale surface from the small scale surface. The mean square heights and slopc_ of the large (and small) scale surfaces depend on the choice of patch sizes. Author Backscattering; Mean Square Values; Radar Cross Sections 20050169713 Georgian Technical Univ., Tbilisi, Georgia Running Power Spectrum of Pulsed Radiation in an Absorptive Randomly Inhomogeneous Media Jandieri, G. V.; Pirtskhalaishvili, N. G.; Jandieri, V. G.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 538-541; In English; See also 20050169565; Copyright; Avail: Other Sources To the problem of pulse signal propagation in a chaotically inhomogeneous media is devoted a great number of papers. The behavior of the Running power spectrum (RPS) of pulsed radiation in a weakly dispersive chaotically nonstationary media was investigated at one-dimensional spatial-temporal permittivity fluctuations using statistical moment method. The investigations of the features of the normalized RPS in absorptive random medium at both one-dimensional spatial-temporal dielectric permittivity and conductivity fluctuations is of interest. Derived from text Pulsed Radiation; Pulse Duration; Electromagnetic Radiation 20050169718 NTT Mobile Communications Network, Inc., Japan Dual Frequency Resonant Base Station Antennas for PDC Systems in Japan Ebine, Yoshio; IEEEAntennas and Propagation Society International Symposium, Volume 1; [1999], pp. 564-567; In English; See also 20050169565; Copyright; Avail: Other Sources Cellular mobile communication systems are being successfully developed all over the world. To accommodate the increase in the number of mobile phone subscribers, multiple systems accessing different frequency bands are being employed. In 1993, PDC (personal digital cellular) systems started operation in the frequency bends of 800MHz and 1500MHz, in Japan. The PDC systems of NTTDoCoMo in Japan also use dual frequency bands, accordingly, the base station antennas used in the PDC system must be dual frequency resonant to reduce the cost and space required for the antenna. This paper presents 61 commercial dual frequency resonant (DF) base station antenna (BSA) and an operation mechanism for a remote-controlled beam tilting system in the vertical plane. Derived from text Pulse Communication; Japan; Antenna Design; Mobile Communication Systems 20050169719 Nippon Telegraph and Telephone Public Corp., Japan Advanced Base Station Antennas for Personal Handy-phone System (PHS) in Japan Hori, Toshikazu; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 572-575; In English; See also 20050169565; Copyright; Avail: Other Sources The Personal Handy-phone System (PHS) is one of the micro-cellular systems now in service in Japan. This system mostly uses rod antennas at the base stations because of their easy installation and low cost; they are usually placed on top of public telephone boxes and utility poles, at the top of towers installed on telephone offices, and on the ceiling of underground shopping area or in buildings, and so on. Obviously antenna heights and installation conditions differ widely. Street microcells are formed in urban areas because most antennas arc surrounded by buildings. Some antennas may be sited on towers and not all sites have the same surroundings, so the base station antennas must offer a wide variety of radiation patterns. Based on a consideration of the propagation characteristics and the installation condition, we have developed several base station antennas. This paper introduces the design concepts and experimental results of these microcell base station antennas for PHS. The fabricated rod antennas are tested in a real propagation environment in an urban area. The trials confirm the validity of our design method and the usefulness of the antennas. Derived from text Japan; Telephones; Antenna Design; Fabrication 20050169724 Yokohama National Univ., Japan Analysis of Patch Antenna with Short Pin by Using Non-Uniform Mesh FDTD Jiang,Huiling; Arai, Hiroyuki; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 610-613; In English; See also 20050169565; Copyright; Avail: Other Sources The need for smaller antennas has become increasingly important in recent years because the effect of large scale integration of electronic components generally isolates the antenna as the most bulky, heavy and obtrusive part of the equipment. But it is an accepted fact that electrically smaller antennas have narrower bandwidths and poorer efficiencies than their larger counterparts. This would incur significant power losses and reduce the general efficiency of the receiver as well as increasing equipment costs. Today more efficient matching techniques are available. For example, for a center fed patch antenna, post pins which were are usually used around the feed pin for matching purpose. This study was proceeded by experimentally way mainly till now. In design of small antennas, optimization of parameters by using numerical simulation is necessary. In early works, numerical simulation by using wire-mesh method and diakoptic theory has been used. Because it is very difficult to deal with the patch structure and wire element simultaneously, numerical analysis of matching technique by using same analysis method haven’t been reported yet. In this paper, we calculated the center fed patch antenna which has two post pins by using FDTD method. To improve the computation efficiency, the FDTD analysis by using non-uniform mesh is used during the simulation. By changing the structure of matching element, examination of matching technique of low profile antenna is carried out in this paper. Author Patch Antennas; Finite Difference Theory; Large Scale Integration; Numerical Analysis 20050169725 MacQuarie Univ., Sydney, Australia FDTD Analysis of an Inclined Microstrip Patch Antenna, Considering Field Singularity at the Edges Esselle, Karu P.; Foroughipour, Mahmoudreza; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 606-609; In English; See also 20050169565; Copyright; Avail: Other Sources A rectangular microstrip patch antenna, inclined to the FDTD grid by 45 deg, is accurately analysed using enhanced FDTD equations for diagonal metal edges. The enhanced equations, derived by considering the singular nature of electromagnetic fields at sharp metal edges, properly model the patch with less number of FDTD cells. The same inclined patch antenna is modelled using two existing techniques as well, namely staircase and split-cell models, for comparison with enhanced equations. The resonance frequencies and the frequency response of the patch are computed using these three techniques, and are compared with a very accurate reference, which is obtained by analyzing a similar patch but kept parallel to a much finer grid. It is found that the enhanced equations give extremely accurate results consistently, without any 62 noticeable computing overhead. For example, the accuracy of the first resonance frequency using the enhanced equations is 1.1%, and that using the staircase and split-cell models is 7.1% and 3.5%, respectively. The enhanced equations are very stable, and are time-stepped at the maximum Courant limit in all simulations without any problems. Author Finite Difference Time Domain Method; Microstrip Antennas; Patch Antennas; Antenna Radiation Patterns; Electromagnetic Fields; Edges; Metal Surfaces 20050169726 Michigan Univ., Ann Arbor, MI, USA Effects of the Fast Multipole Method (FMM) Parameters on Radar Cross Section Computations Sertel, K.; Volakis, J. L.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 624-627; In English; See also 20050169565; Copyright; Avail: Other Sources The Method of Moments (MoM) has been successfully applied to all types of electromagnetic scattering and radiation problems. As is well known, conventional MoM techniques lead to fully populated interaction matrices. This aspect limits the electrical size of the problem that can be solved on a given computer with limited memory. Recently introduced fast methods, such as the adaptive integral method (AIM) and fast multipole method (FMM), provide for reduced memory and CPU requirements. In this paper we consider the implementation of FMM to MoM matrices associated with 2nd order curvilinear elements. Particular emphasis is given on the convergence properties and accuracy of FMM acceleration schemes. It is demonstrated that preconditioning is often essential when dealing with FMM matrices generated from curvilinear element implementations. Also, choices of lower order multipole expansions can lead to much faster speeds but lower accuracy. Author Radar Cross Sections; Multipoles; Method of Moments 20050169732 Raytheon Systems Co., Sudbury, MA, USA A Milstar Low Profile Antenna Chang, Y.; Sarcione, M.; Beltran, F.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 684-687; In English; See also 20050169565; Copyright; Avail: Other Sources A low profile antenna/pedestal system for the Milstar program was developed at Raytheon under an Air Force contract. The system was designed to have minimum intrusion inside the aircraft and no protrusion outside the aircraft so that the radome is flush to the fuselage. The main drivers of this antenna design include low cost, minimum height, and high efficiencies for both K-band (20.2 -21.2 GHz) and Q-band (43.5 - 45.5 GHz). The approach Raytheon chose was a 20 inch wide 9.5 inch high elliptical offset dual-shaped Gregorian reflector with a compact concentric feed as shown. The main challenge of such an elliptical aperture design is optimizing the antenna efficiency. Shaping approaches reported by P-S. Kildal offer an excellent solution to this problem. These approaches were used to synthesize the main reflector and subreflector and to analyze the antenna performance. After a thorough tradeoff study, a reflector configuration meeting the design driving factors as shown was chosen. This figure includes front and side views with ray tracing lines to indicate the energy spread. Despite blockage by the feed and the subreflector, this configuration offers the maximum effective antenna aperture under the height constrain. In synthesizing the reflector surfaces, a -15 dB taper was chosen at the subreflector edge to minimize the spillover loss. To maximize the illumination efficiency, a -3 dB edge taper on the antenna aperture was chosen. Since circular polarization is required for both K- and Q-bands, a compact concentric feed with symmetric feed patterns was selected. The Q-band feed in the center has a dielectric launching rod, and the feed horn is a multi-mode horn with a 1.05 inch diameter. A septum polarizer is used to generate circular polarization for Q-band and dielectric vanes are used in the K-band coaxial waveguide. Typical measured feed patterns are shown. Derived from text Antenna Design; Systems Engineering; Dielectrics 20050169734 Vertex Communications Corp., Kilgore, TX, USA A Dual Band Low PIM Feed System for Cassegrain Applications Beadle, Mark; Casey, Sean; Schwerdtfeger, Roland; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 696-699; In English; See also 20050169565; Copyright; Avail: Other Sources Multi-frequency band, multi-function satellite communications antenna systems, and in some instances, limited ground facilities, have in recent times required complex single aperture feed system designs. The normal approach involves the inherent frequency selection characteristics of the periodic structure of the corrugated horn. Interesting design problems occur in the coupling junction at which frequency selection/separation takes place, to ensure complete lossless decoupling between 63 [...]... offer compliant antenna performance Typical examples of such designs are: 2/ 8 GHz, 4/7/ 12 GHz, 2/ 4 GHz, 11/14/18 GHz, 4/ 12 GHz, 12/ 20 GHz, all involving adjustable and/ or switchable CP/LP polarization configurations in one form or another The following briefly describes the more unusual aspects of the 1.75- 1.85 / 2. 2 -2. 3 GHz and 7 .25 -7.75 / 7.9-8.4 GHz feed for a 9m Cassegrain having also to comply with... amplifier was designed for operation at 33 GHz and fabricated in a standard MMIC foundry process with 0 .20 -m PHEMT devices Using a 20 -V bias supply, the amplifier achieved efficiencies of over 40 percent with an output power of 0.66 W and a 16-dB gain over a 2- GHz bandwidth centered at 33 GHz With a 28 -V bias, a power level of 1.1 W was achieved with a 12- dB gain and a 36-percent efficiency This represents... and microelectronics and integrated circuitry for related information see also 60 Computer Operations and Hardware; and 76 Solid-State Physics For communications equipment and devices see 32 Communications and Radar 20 050169565 Institute of Electrical and Electronics Engineers, Piscataway, NJ, USA IEEE Antennas and Propagation Society International Symposium, Volume 1 [1999]; 721 pp.; In English; Held... less than 1 and 1.3 dB and return losses of more than 20 and 15 dB in the pass bands centered near 5 GHz We obtained a good agreement between the measured and calculated performances These filters behave similarly to the conventional open-circuited shunt-stub band-pass filters, but are smaller and have less radiation, dispersion, and sensitivity to the adjacent objects Derived from text Bandpass Filters;... K.; Paxton, S T.; Hadaway, S.; Lunar and Planetary Science XXXVI, Part 12; [20 05]; 2 pp.; In English; See also 20 0501709 42; Original contains color and black and white illustrations; Copyright; Avail: CASI; A01, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document Ground Penetrating Radar (GPR) is used to view the subsurface of soil and rock layers GPR uses electromagnetic... for the bandwidth Derived from text Amplification; Bandwidth; Antenna Design; Communication Equipment 20 050169585 Deltec New Zealand Ltd., New Zealand Adjustable Multifilar Helical Antenna with Reduced Frequency Scanning duToit, C F.; Chadwick, P E.; Butland, R J.; Vaughan, R G.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp 18 -21 ; In English; See also 20 050169565;... Dielectrics 78 20 050169 623 Illinois Univ at Urbana-Champaign, Urbana, IL, USA Fast Multipole Acceleration Using Impedance Matrix Localization Michielssen, Eric; Shanker, Balasubramaniam; Han, Sang-Kyun; Chew, W C.; IEEE Antennas and Propagation Society International Symposium, Volume 1; [1999], pp 620 - 623 ; In English; See also 20 050169565 Contract(s)/Grant(s): F49 620 -96-1-0 025 ; NSF ECS-95- 021 38; Copyright;... the bandwidth is only 2. 03% and the height of the patch is too high In this paper, a new small two-layer microstrip patch is proposed Author Miniaturization; Cross Polarization; Microstrip Antennas; Patch Antennas; Permittivity; Bandwidth 20 050169630 Vertex Communications Corp., Kilgore, TX, USA A Tri-band Reflector Antenna with Dual Band TE(sub 21 ) Mode Tracking Patel, Sharad; Schwerdtfeger, Roland;... Guard Law Enforcement and Homeland Security Missions Klopson, Jadon E.; Burdian, Stephen V.; Mar 20 05; 109 pp.; In English; Original contains color illustrations Report No.(s): AD-A4 322 85; No Copyright; Avail: Defense Technical Information Center (DTIC) This thesis analyzes the potential impact of incorporating wireless technologies, specifically an 8 02. 11 mesh layer architecture and 8 02. 16 Orthogonal Frequency... establish a Theater Special Operations Command North to exercise command and control of special operations forces conducting operations in the USNORTHCOM AOR DTIC Command and Control; Military Personnel 20 050173196 Defense Science Board, Washington, DC USA Report of the Defense Science Board 1996 Task Force on Command, Control, Communications, Intelligence, Surveillance and Reconnaissance (C4ISR) integration . Antennas and Propagation Society International Symposium, Volume 1; [1999], pp. 23 0 -23 3; In English; See also 20 050169565 Contract(s)/Grant(s): F49 620 -96-1-0 025 ; N00014-95-1-08 72; NSF ECS-93- 021 45;. elements and its arrays were fabricated and tested at X-band. The 3-dB axial-ratio bandwidth obtained from this new type of DRA array was about 20 % at X-band, and it had an extremely broadband performance compared. cost, minimum height, and high efficiencies for both K-band (20 .2 -21 .2 GHz) and Q-band (43.5 - 45.5 GHz). The approach Raytheon chose was a 20 inch wide 9.5 inch high elliptical offset dual-shaped