The author applies the Neumann series method to the combined integral equation. An important goal of this work is to find an iterative method which is useful for wavelengths much smaller than the scatterer. One application of the result is to determine corrections to physical optics. Particularly interesting examples are those to which physical optics is a poor approximation, even in the high-frequency limit. An example of such a problem is shown.<>
{"title":"A high-frequency iterative method using the combined integral equation","authors":"R. Marks","doi":"10.1109/APS.1989.134675","DOIUrl":"https://doi.org/10.1109/APS.1989.134675","url":null,"abstract":"The author applies the Neumann series method to the combined integral equation. An important goal of this work is to find an iterative method which is useful for wavelengths much smaller than the scatterer. One application of the result is to determine corrections to physical optics. Particularly interesting examples are those to which physical optics is a poor approximation, even in the high-frequency limit. An example of such a problem is shown.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77281466","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}
The authors present an approach to the numerical modeling of three-dimensional scattering in conductive media. The particular class of problems of interest is that for which the conduction current is large enough that the displacement current may be neglected. The scattering objects of interest are those which are on the order of a skin depth in size. The approach is based on the unimoment method extended to scattering from arbitrary three-dimensional objects and conductive media. A flow diagram of the computational tasks which must be performed in order to generate a solution is presented.<>
{"title":"Numerical modeling of three dimensional scattering in conductive media","authors":"G. T. Shoemaker, L. Roemer","doi":"10.1109/APS.1989.134977","DOIUrl":"https://doi.org/10.1109/APS.1989.134977","url":null,"abstract":"The authors present an approach to the numerical modeling of three-dimensional scattering in conductive media. The particular class of problems of interest is that for which the conduction current is large enough that the displacement current may be neglected. The scattering objects of interest are those which are on the order of a skin depth in size. The approach is based on the unimoment method extended to scattering from arbitrary three-dimensional objects and conductive media. A flow diagram of the computational tasks which must be performed in order to generate a solution is presented.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89017269","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}
The authors have developed a spatial decomposition (SD) approach for the method of moments (MM) that shows substantial promise in reducing both the dimensionality and ill-conditioning of the computational burden. In fact, SD permits the maximum size of the MM system matrix that needs to be inverted to be strictly limited, regardless of the electrical size of the target being modeled. SD provides the means of implementing the combined-field surface-patching MM technique with a computer memory and execution time requirement of order M, where M is the number of spatial subzones. SD has been successfully applied to electrically large two-dimensional dielectric targets and three-dimensional conducting bodies of revolution.<>
{"title":"Spatial decomposition for the method of moments (EM field problems)","authors":"K. Umashankar, A. Taflove","doi":"10.1109/APS.1989.134751","DOIUrl":"https://doi.org/10.1109/APS.1989.134751","url":null,"abstract":"The authors have developed a spatial decomposition (SD) approach for the method of moments (MM) that shows substantial promise in reducing both the dimensionality and ill-conditioning of the computational burden. In fact, SD permits the maximum size of the MM system matrix that needs to be inverted to be strictly limited, regardless of the electrical size of the target being modeled. SD provides the means of implementing the combined-field surface-patching MM technique with a computer memory and execution time requirement of order M, where M is the number of spatial subzones. SD has been successfully applied to electrically large two-dimensional dielectric targets and three-dimensional conducting bodies of revolution.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89054679","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}
Using an approximate synthesis procedure, a practical undersized backfire antenna (BFA) with a nonuniform corrugated rod structure was developed. Many backfire antenna designs with synthesized corrugated surface-wave rods were manufactured and tested. A comparison between the parameters of two long backfire antennas having the same basic dimensions but differing in the surface-wave (SW) structures (uniform and modulated) is presented. It is found that a BFA with a synthesized nonuniform SW structure has an optimum directivity. An undersized backfire antenna with a nonuniform corrugated rod designed for an optimum frequency of 2.0 GHz is described.<>
{"title":"Undersized long backfire antenna","authors":"H. Hristov, G. Kirov, J. Urumov","doi":"10.1109/APS.1989.134972","DOIUrl":"https://doi.org/10.1109/APS.1989.134972","url":null,"abstract":"Using an approximate synthesis procedure, a practical undersized backfire antenna (BFA) with a nonuniform corrugated rod structure was developed. Many backfire antenna designs with synthesized corrugated surface-wave rods were manufactured and tested. A comparison between the parameters of two long backfire antennas having the same basic dimensions but differing in the surface-wave (SW) structures (uniform and modulated) is presented. It is found that a BFA with a synthesized nonuniform SW structure has an optimum directivity. An undersized backfire antenna with a nonuniform corrugated rod designed for an optimum frequency of 2.0 GHz is described.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86048991","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}
The essentials of a method developed to obtain the cross section of perfectly conducting targets by considering the surface current components induced on the bodies is presented. This approach treats the surface traveling wave phenomenon, allowing it to be included in RCS (radar cross section) computations for complex objects.<>
{"title":"High frequency radar cross section prediction","authors":"T. Sengor","doi":"10.1109/APS.1989.134832","DOIUrl":"https://doi.org/10.1109/APS.1989.134832","url":null,"abstract":"The essentials of a method developed to obtain the cross section of perfectly conducting targets by considering the surface current components induced on the bodies is presented. This approach treats the surface traveling wave phenomenon, allowing it to be included in RCS (radar cross section) computations for complex objects.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86145068","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}
The authors develop a new model for implementing adaptive nulling of interfering signals which is based solely on a single-feed horn antenna. The model uses a multimode feed antenna in which various modes are generated or extracted by means of slot coupling. Adaptive nulling is then carried out by treating each mode as an element of a phased-array antenna. The algorithm that is used to implement the adaptive nulling relies quite heavily on the QR decomposition method, a recursive least-squares algorithm which is amenable to systolic array processing. With proper choice of modes and design parameters for the feed horn antenna, simulation studies show that wide beamwidths (bandwidth), low sidelobe levels, and high signal-to-noise and interference ratio can be achieved with the proposed adaptive beamforming technique.<>
{"title":"Adaptive beamforming using multimode feed horn antennas","authors":"T. Van Ho, J. Litva","doi":"10.1109/APS.1989.135046","DOIUrl":"https://doi.org/10.1109/APS.1989.135046","url":null,"abstract":"The authors develop a new model for implementing adaptive nulling of interfering signals which is based solely on a single-feed horn antenna. The model uses a multimode feed antenna in which various modes are generated or extracted by means of slot coupling. Adaptive nulling is then carried out by treating each mode as an element of a phased-array antenna. The algorithm that is used to implement the adaptive nulling relies quite heavily on the QR decomposition method, a recursive least-squares algorithm which is amenable to systolic array processing. With proper choice of modes and design parameters for the feed horn antenna, simulation studies show that wide beamwidths (bandwidth), low sidelobe levels, and high signal-to-noise and interference ratio can be achieved with the proposed adaptive beamforming technique.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90586940","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}
The key features of the TDRSS (tracking and data relay satellite system) antennas are presented. Descriptions are given of the multiple-access antenna, the two single-access antennas, the space-to-ground link antenna, and the omni antenna. Integration and tests are also discussed.<>
{"title":"TDRSS spacecraft antenna farm","authors":"G. Wong, S. Hamada, P. W. Low","doi":"10.1109/APS.1989.134732","DOIUrl":"https://doi.org/10.1109/APS.1989.134732","url":null,"abstract":"The key features of the TDRSS (tracking and data relay satellite system) antennas are presented. Descriptions are given of the multiple-access antenna, the two single-access antennas, the space-to-ground link antenna, and the omni antenna. Integration and tests are also discussed.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84041585","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}
A design for a dual-reflector compact range system with axial-symmetric main reflector is proposed. The advantage of this design is that it provides a larger quiet zone area and reduces the manufacturing cost. The configuration consists of a large surface of revolution as primary mirror, and a conventional point-source spherical-wave feed. The point-source feed is located outside the column of parallel rays reflected from the primary mirror in the Z-axis. Using geometrical ray tracing, a subreflector contour can be generated. Since the proposed approach is based on the surface of revolution, either a paraboloid or a spherical surface can be chosen as the main reflector.<>
{"title":"Compact range design with axial-symmetric main reflector","authors":"D. Chang, S.-Y. Yang, M.-R. Ho","doi":"10.1109/APS.1989.134684","DOIUrl":"https://doi.org/10.1109/APS.1989.134684","url":null,"abstract":"A design for a dual-reflector compact range system with axial-symmetric main reflector is proposed. The advantage of this design is that it provides a larger quiet zone area and reduces the manufacturing cost. The configuration consists of a large surface of revolution as primary mirror, and a conventional point-source spherical-wave feed. The point-source feed is located outside the column of parallel rays reflected from the primary mirror in the Z-axis. Using geometrical ray tracing, a subreflector contour can be generated. Since the proposed approach is based on the surface of revolution, either a paraboloid or a spherical surface can be chosen as the main reflector.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88001203","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}
The OLYMPUS 1 spacecraft antenna farm is described, including TVB1, the 12 GHz Italian beam transmit used with the TV broadcast payload; TVB2, the 12 GHz european transmit used with the TV broadcast payload; TVB3, the 18 GHz European receive used with the TV broadcast payload; multibeam, the 12/13 GHz spotbeam antenna used with the specialized services payload; the 20/30 GHz communications antenna; 12/20/30 GHz beacons used with the propagation payload; and the 5-band TT and C (telemetry, tracking, and command) antenna. Interference and problems associated with integration are also assessed.<>
{"title":"The OLYMPUS spacecraft antenna farm","authors":"B.J. Culham","doi":"10.1109/APS.1989.134735","DOIUrl":"https://doi.org/10.1109/APS.1989.134735","url":null,"abstract":"The OLYMPUS 1 spacecraft antenna farm is described, including TVB1, the 12 GHz Italian beam transmit used with the TV broadcast payload; TVB2, the 12 GHz european transmit used with the TV broadcast payload; TVB3, the 18 GHz European receive used with the TV broadcast payload; multibeam, the 12/13 GHz spotbeam antenna used with the specialized services payload; the 20/30 GHz communications antenna; 12/20/30 GHz beacons used with the propagation payload; and the 5-band TT and C (telemetry, tracking, and command) antenna. Interference and problems associated with integration are also assessed.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88494729","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}
The authors present a study of the spectral properties of cascaded gratings whose individual gratings are placed at different angles with respect to each other at each different layer. The reflection and transmission profiles that result from such an arrangement are discussed and compared with the parallel arrangement. The special case of the unbonded mesh is compared with published data. Moreover, the effects of inserting dielectric slabs between the gratings in this type of cascaded structure are presented.<>
{"title":"Scattering from cascaded gratings with variable orientation at each layer","authors":"S. Shi, C. Christodoulou","doi":"10.1109/APS.1989.134884","DOIUrl":"https://doi.org/10.1109/APS.1989.134884","url":null,"abstract":"The authors present a study of the spectral properties of cascaded gratings whose individual gratings are placed at different angles with respect to each other at each different layer. The reflection and transmission profiles that result from such an arrangement are discussed and compared with the parallel arrangement. The special case of the unbonded mesh is compared with published data. Moreover, the effects of inserting dielectric slabs between the gratings in this type of cascaded structure are presented.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88341189","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}
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