IEEE Antennas and Propagation Society International Symposium 1997. Digest最新文献_第4页

Electromagnetic scattering from targets above rough surfaces 来自粗糙表面上目标的电磁散射

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631762

T. Chiu, K. Sarabandi

引用次数: 0

Comparison of GTD and FDTD predictions for UHF radio wave propagation in a simple outdoor urban environment 城市简单室外环境下UHF无线电波传播的GTD和FDTD预测比较

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631735

J. Schuster, R. Luebbers

{"title":"Comparison of GTD and FDTD predictions for UHF radio wave propagation in a simple outdoor urban environment","authors":"J. Schuster, R. Luebbers","doi":"10.1109/APS.1997.631735","DOIUrl":"https://doi.org/10.1109/APS.1997.631735","url":null,"abstract":"The continuing growth of wireless communication systems has led to an interest in the development of site-specific propagation models. In designing microcell systems there is a often a desire to have a good understanding of the propagation characteristics within the cell. Site-specific models offer a fast and inexpensive means of obtaining this information without the need for on-site measurements. The finite difference time domain (FDTD) method was initially developed by Yee in 1966. The method is commonly applied to three-dimensional scattering and radiation problems. But with the exception of analyzing the propagation within a single room, even the largest computers do not have nearly enough memory to model full three-dimensional indoor or outdoor propagation problems. However, in many cases a two-dimensional approximation to the geometry can be used, and two-dimensional FDTD has previously been applied to indoor propagation. This paper considers the application of 2D FDTD to a simple outdoor environment and develops a simple approach for introducing the correct spherical wave spreading. Comparisons to FDTD predictions could be used to evaluate and refine the GTD based methods.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":" 38","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113951524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 38

Variation of field strength in underground mine area on the size of VLF loop antennas laid on the Earth surface 地下矿区场强随地表VLF环形天线尺寸的变化

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631526

A. K. Gogoi, R. Raghuram

引用次数: 3

Calibration of polarimetric radar systems 极化雷达系统的校正

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631589

L. Muth, R. Wittmann

引用次数: 2

Design criteria for wideband active phased array antennas 宽带有源相控阵天线设计准则

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631561

A. Agrawal, E.L. Williamson, J. Ferrante

{"title":"Design criteria for wideband active phased array antennas","authors":"A. Agrawal, E.L. Williamson, J. Ferrante","doi":"10.1109/APS.1997.631561","DOIUrl":"https://doi.org/10.1109/APS.1997.631561","url":null,"abstract":"The instantaneous bandwidth of a phased array antenna can be increased by dividing the aperture into subarrays and placing a time delay network behind each subarray. The size of the subarray determines the instantaneous bandwidth of the antenna. Bandwidth criteria for phased array antennas were previously developed for both narrow band signal with frequency agility and for instantaneous wideband signals. The bandwidth criteria were defined in terms of loss of antenna gain and relative amplitude of grating lobes. Radars may apply an amplitude weighting to the received pulse in order to reduce time sidelobes. This weighting for an LFM (linear frequency modulated) wide bandwidth pulse effectively tapers the contribution from frequencies off midband, resulting in progressively more effective suppression of instantaneous grating lobes out to the edge of the band. The pulse compression of this time weighted receive pulse is formed from the sum of the contributions from the receive patterns over the bandwidth. The process of time weighted LFM pulse compression produces a return that has an effective antenna receive grating lobe contribution much less than that is exhibited by the instantaneous patterns at the band edges. In this paper we examine the receive sidelobe performance of a phased array antenna for instantaneous wide bandwidth after an amplitude taper is applied in the radar receiver.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126329024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

On the evaluation of spatial domain MoM matrix entries containing closed form Green's functions 含封闭格林函数的空间域MoM矩阵项的求值

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.625440

N. Kınayman, M. I. Aksun, Raj Mittra

{"title":"On the evaluation of spatial domain MoM matrix entries containing closed form Green's functions","authors":"N. Kınayman, M. I. Aksun, Raj Mittra","doi":"10.1109/APS.1997.625440","DOIUrl":"https://doi.org/10.1109/APS.1997.625440","url":null,"abstract":"The method of moments (MoM) is widely-used for the solution of mixed potential integral equations (MPIE) arising in the analysis of planar stratified geometries. However, the application of this technique in the spatial domain poses some difficulties since the associated spatial-domain Green's functions for these geometries are improper oscillatory integrals, known as Sommerfeld integrals, that are very computationally-intensive to evaluate. It is possible to eliminate the time-consuming task of computing these integrals by using closed form versions of the spatial domain Green's functions and the time required to evaluate the reaction integrals in the MoM matrix can be reduced considerably. Furthermore, the reaction integrals resulting from the application of the MoM can also be evaluated analytically by using piecewise linear basis and testing functions (Alatan et al., 1996). Hence, an efficient EM simulation algorithm can be developed by using the closed form Green's functions in the MoM formulation that involves no numerical integration. However, despite the time-saving realized from the analytical evaluation of the reaction integrals with the closed-form Green's functions, the need for further reducing the matrix fill-time is not obviated for many problems. Thus the objective of this paper is to present a hybrid technique for the evaluation of the MoM reaction integrals in a numerically-efficient manner that further reduces the time needed for their computation. A microstrip patch antenna is used as an example.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121946496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Integral equations for scattering by a particle in a layer 层中粒子散射的积分方程

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631601

E. Marx

引用次数: 4

Active polarization-agile microstrip antennas 有源极化-敏捷微带天线

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.630062

P. Haskins, S.S. Dahele

引用次数: 2

Multiple quantum well in-line optical modulators using tunable distributed Bragg gratings photonically controlled active array 采用可调谐分布式布拉格光栅的多量子阱直列光调制器

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.631571

F. Jain, E. Heller, D. Parent, H. Wang, W. Zappone, S. Srinivasan, S. Cheung, W. Huang, R. Bansal, J. Preiss, L. Green, Á. Marinilli, M. Russell

{"title":"Multiple quantum well in-line optical modulators using tunable distributed Bragg gratings photonically controlled active array","authors":"F. Jain, E. Heller, D. Parent, H. Wang, W. Zappone, S. Srinivasan, S. Cheung, W. Huang, R. Bansal, J. Preiss, L. Green, Á. Marinilli, M. Russell","doi":"10.1109/APS.1997.631571","DOIUrl":"https://doi.org/10.1109/APS.1997.631571","url":null,"abstract":"The integration of photonic technology into phased array radar systems promises to reduce aperture, weight, size, transmit/receive (T/R) module complexity, mitigate EMI, and accommodate wider signal bandwidth with frequency independent beam steering. One of the photonic control methodology is to employ true time delays which have been incorporated in a variety of ways in the realization of phased array radar. We have proposed a technique using wavelength division multiplexing (WDM) to address a large number of elements, with each clement carrying the phase information on one channel/wavelength. This architecture is optically non-coherent and achieves a reduction in hardware complexity via sharing of various devices. As part of the Office of Naval Research's Accelerated Capabilities initiative, Raytheon/University of Connecticut team is developing and implementing this methodology. This paper focuses on the devices, including novel waveguide amplitude modulators and tunable filters, required to implement such an architecture. In particular, we propose to employ the quantum confined Stark effect in 1.55 micron InGaAsP/InP multiple quantum well (MQWs) for these components. We intend to use the quadratic electrorefractive effect in InGaAsP (1.5 /spl mu/m)/InGaAsP (1.3 /spl mu/m) and/or InGaAsP (1.5 /spl mu/m)/InP multiple quantum well (MQW) structures to achieve intensity modulation with the applied signal voltage. The investigation focuses on MQW devices which exhibit the quantum confined Stark effect since these devices yield large changes of refractive index with low insertion loss and are capable of being modulated at the required frequencies. The details of modulator structures are described.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134017960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cell forming technique by polarization and pattern of base station antenna 利用基站天线的极化和方向图形成小区技术

IEEE Antennas and Propagation Society International Symposium 1997. Digest Pub Date : 1997-07-13 DOI: 10.1109/APS.1997.625520

Kyeong-Sik Min, M. Tanaka, H. Arai

引用次数: 0