Experimental studies of the frequency-swept microwave image reconstruction scheme for perfectly conducting objects in a bistatic backward scattering arrangement are presented. The measurement system and calibration procedure are described. Experimental results are presented on two types of scattering objects: discrete line scatterers of four distributed metallic thin cylinders with length 113 cm and radius a = 0.5 cm, and a complex scattering object of a 1:100 metal-covered B-52 scale model aircraft.<>
{"title":"Bistatic frequency-swept microwave imaging measurement system","authors":"D.-B. Lin, T. Chu","doi":"10.1109/APS.1993.385579","DOIUrl":"https://doi.org/10.1109/APS.1993.385579","url":null,"abstract":"Experimental studies of the frequency-swept microwave image reconstruction scheme for perfectly conducting objects in a bistatic backward scattering arrangement are presented. The measurement system and calibration procedure are described. Experimental results are presented on two types of scattering objects: discrete line scatterers of four distributed metallic thin cylinders with length 113 cm and radius a = 0.5 cm, and a complex scattering object of a 1:100 metal-covered B-52 scale model aircraft.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128103433","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 determination of the resonances of a PEC (perfectly electrically conducting) sphere embedded in an eccentric spherical dielectric shell is considered. Generally, the structure is PEC object with a nonuniform dielectric coating. When the eccentricity equals zero, the scatterer degenerates to a uniformly coated PEC sphere. Some numerical results are given.<>
{"title":"Accurate determination of SEM poles of a PEC sphere embedded in an eccentric spherical dielectric shell","authors":"L.-Y. Zhang, P. Wang, W. Wang, L. Jen","doi":"10.1109/APS.1993.385196","DOIUrl":"https://doi.org/10.1109/APS.1993.385196","url":null,"abstract":"The determination of the resonances of a PEC (perfectly electrically conducting) sphere embedded in an eccentric spherical dielectric shell is considered. Generally, the structure is PEC object with a nonuniform dielectric coating. When the eccentricity equals zero, the scatterer degenerates to a uniformly coated PEC sphere. Some numerical results are given.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125458220","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 two-stage radial motion compensation technique for removing distortion in inverse synthetic-aperture radar (ISAR) images. The first stage is aimed at removing the gross radial motion (i.e., range cell alignment) using the mean value method. The second stage attempts to remove the residual phase variations not corrected in the first stage using a weighted phase regulation algorithm. It is shown that irregular translation motion of targets can be converted into rotating motion around a fixed axis. The resulting images in the microwave anechoic chamber and onsite are given.<>
{"title":"Motion compensation for ISAR imaging using weights","authors":"Y. Zhang, Z. Chen","doi":"10.1109/APS.1993.385581","DOIUrl":"https://doi.org/10.1109/APS.1993.385581","url":null,"abstract":"The authors present a two-stage radial motion compensation technique for removing distortion in inverse synthetic-aperture radar (ISAR) images. The first stage is aimed at removing the gross radial motion (i.e., range cell alignment) using the mean value method. The second stage attempts to remove the residual phase variations not corrected in the first stage using a weighted phase regulation algorithm. It is shown that irregular translation motion of targets can be converted into rotating motion around a fixed axis. The resulting images in the microwave anechoic chamber and onsite are given.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115960769","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 Lippman-Schwinger integrodifferential equation is used to develop two new characteristics of the scattering amplitude tensor for an arbitrary scatterer. It is used to show that the plane-wave spectrum of the scattered field can be expressed in terms of the scattering amplitude tensor. It is also used to develop a nonsingular integral equation for the scattering amplitude tensor. For a very small scatterer, the solution of the scattering amplitude tensor integral equation leads to an equivalent polarizability tensor. This tensor differs from the conventional Rayleigh approximation in its frequency dependence and because it includes a radiative reaction term.<>
{"title":"One application of Lippman-Schwinger integral equation to scattering from an arbitrary scatterer","authors":"M. Karam, D. LeVine","doi":"10.1109/APS.1993.385199","DOIUrl":"https://doi.org/10.1109/APS.1993.385199","url":null,"abstract":"The Lippman-Schwinger integrodifferential equation is used to develop two new characteristics of the scattering amplitude tensor for an arbitrary scatterer. It is used to show that the plane-wave spectrum of the scattered field can be expressed in terms of the scattering amplitude tensor. It is also used to develop a nonsingular integral equation for the scattering amplitude tensor. For a very small scatterer, the solution of the scattering amplitude tensor integral equation leads to an equivalent polarizability tensor. This tensor differs from the conventional Rayleigh approximation in its frequency dependence and because it includes a radiative reaction term.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129982186","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}
In the evaluation of hypersingular integrals for scattering by a dielectric wedge, the neighboring-patch contributions were previously examined under the assumption that the small-argument approximation of the Hankel functions could be used. In the present work, this assumption is relaxed. Similar corrections are required in the computation of the field components when the distance between the field point and the patch is small compared to the wavelength. Although the field integrals are finite, the behavior of the integrand is the same as that for the neighboring-patch contributions.<>
{"title":"Numerical evaluation of hypersingular integrals for scattering by a dielectric wedge","authors":"E. Marx","doi":"10.1109/APS.1993.385202","DOIUrl":"https://doi.org/10.1109/APS.1993.385202","url":null,"abstract":"In the evaluation of hypersingular integrals for scattering by a dielectric wedge, the neighboring-patch contributions were previously examined under the assumption that the small-argument approximation of the Hankel functions could be used. In the present work, this assumption is relaxed. Similar corrections are required in the computation of the field components when the distance between the field point and the patch is small compared to the wavelength. Although the field integrals are finite, the behavior of the integrand is the same as that for the neighboring-patch contributions.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130148832","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}
To take maximum advantage of integrated circuit techniques, completely planar geometry should be chosen for tapered slot antennas. This is the reason that the transition used in the present study is microstrip-to-slotline instead of finline to slotline or some other nonplanar transition. The authors investigate the microstrip-to-slotline transition and report on experimental results for Vivaldi antennas of various lengths and output widths. The Vivaldi antennas were designed to operate at 10 GHz and fabricated on Duroid 5870. The directivity in the E- and H-plane for the optimized antenna is shown. The values for the directivity compared favorably to the curves produced by F.J. Zucker (1961) which are the standards for determining whether tapered slot antennas behave as well as optimized traveling-wave antennas.<>
{"title":"Characterization of Vivaldi antennas utilizing a microstrip-to-slotline transition","authors":"D. Burrell, J. Aberle","doi":"10.1109/APS.1993.385130","DOIUrl":"https://doi.org/10.1109/APS.1993.385130","url":null,"abstract":"To take maximum advantage of integrated circuit techniques, completely planar geometry should be chosen for tapered slot antennas. This is the reason that the transition used in the present study is microstrip-to-slotline instead of finline to slotline or some other nonplanar transition. The authors investigate the microstrip-to-slotline transition and report on experimental results for Vivaldi antennas of various lengths and output widths. The Vivaldi antennas were designed to operate at 10 GHz and fabricated on Duroid 5870. The directivity in the E- and H-plane for the optimized antenna is shown. The values for the directivity compared favorably to the curves produced by F.J. Zucker (1961) which are the standards for determining whether tapered slot antennas behave as well as optimized traveling-wave antennas.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133833704","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 experimental methods used to collect the propagation data from the Space Station Freedom are discussed. For the space station modules considered it can be seen that, when the units have a large number of random scatterers, the fields tend to follow a Rayleigh distribution when the transmitter is stationary and the receiver moves throughout the volume. If both transmitter and receiver remain stationary, the field distribution becomes Rice-distributed. This would agree with the general theory that a Rice-distributed field has a strong line-of-sight component affecting the distribution. Finally, it is shown that, when the volume lacks sufficient scatterers, the field distribution no longer behaves predictably. This is due to the fact that, when the obstacles are removed, the module begins to resemble a simple cylindrical cavity and lacks enough random qualities to create a Rayleigh or Rice field distribution.<>
{"title":"A study of indoor propagation: Theory and results of the wireless communication system for the Space Station Freedom","authors":"M. Tobin, J. Richie","doi":"10.1109/APS.1993.385165","DOIUrl":"https://doi.org/10.1109/APS.1993.385165","url":null,"abstract":"The experimental methods used to collect the propagation data from the Space Station Freedom are discussed. For the space station modules considered it can be seen that, when the units have a large number of random scatterers, the fields tend to follow a Rayleigh distribution when the transmitter is stationary and the receiver moves throughout the volume. If both transmitter and receiver remain stationary, the field distribution becomes Rice-distributed. This would agree with the general theory that a Rice-distributed field has a strong line-of-sight component affecting the distribution. Finally, it is shown that, when the volume lacks sufficient scatterers, the field distribution no longer behaves predictably. This is due to the fact that, when the obstacles are removed, the module begins to resemble a simple cylindrical cavity and lacks enough random qualities to create a Rayleigh or Rice field distribution.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132603206","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}
It is shown how to apply genetic algorithms (GAs) to arrive at an optimally thinned array. Consistent GA results from five array thinning optimizations for a 50-element linear array of isotropic point sources are shown. All of the runs are within 0.8dB of one another. A sample far-field pattern for the 50-element array resulting from the GA optimization is shown. The array patterns are optimized for the lowest maximum sidelobe level. It is concluded that a GA is ideal for optimizing the thinning of an array. The bits in a gene correspond to turning the element on or off. Although a GA is slow, it can handle very large problems involving many antenna elements.<>
{"title":"Thinned arrays using genetic algorithms","authors":"R. Haupt, J. J. Menozzi, C. J. McCormack","doi":"10.1109/APS.1993.385248","DOIUrl":"https://doi.org/10.1109/APS.1993.385248","url":null,"abstract":"It is shown how to apply genetic algorithms (GAs) to arrive at an optimally thinned array. Consistent GA results from five array thinning optimizations for a 50-element linear array of isotropic point sources are shown. All of the runs are within 0.8dB of one another. A sample far-field pattern for the 50-element array resulting from the GA optimization is shown. The array patterns are optimized for the lowest maximum sidelobe level. It is concluded that a GA is ideal for optimizing the thinning of an array. The bits in a gene correspond to turning the element on or off. Although a GA is slow, it can handle very large problems involving many antenna elements.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132793398","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}
Two improvements of the fictitious sources in the GMT are proposed: (1) employing the magnetic dipole to simplify the geometry of the electric dipole; and (2) using the sinusoidal current distribution on the dipoles to replace the uniform one for simplifying the field expression. Numerical results verify that the computing efficiency of this improved GMT is obviously increased.<>
{"title":"The improvements of fictitious sources in GMT EM scattering","authors":"Z.N. Chen, W. Zhang, H.Q. Du","doi":"10.1109/APS.1993.385282","DOIUrl":"https://doi.org/10.1109/APS.1993.385282","url":null,"abstract":"Two improvements of the fictitious sources in the GMT are proposed: (1) employing the magnetic dipole to simplify the geometry of the electric dipole; and (2) using the sinusoidal current distribution on the dipoles to replace the uniform one for simplifying the field expression. Numerical results verify that the computing efficiency of this improved GMT is obviously increased.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130709236","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 US Air Force Institute of Technology (AFIT) offers a variety of master's degree programs in engineering which cater to the needs of the Air Force. One of the hallmarks of the low observables curriculum is a unique graduate level course entitled "Radar Cross Section (RCS) Analysis, Measurement, and Reduction." The author describes this particular course, and its role in the low observables curriculum. Graduates praise the experience of making their own RCS measurements in AFIT's laboratory as being extremely beneficial in understanding the usefulness and limitations of data presented to them later by government contractors.<>
{"title":"A unique and practical graduate course in radar cross section at the Air Force Institute of Technology","authors":"J. P. Skinner","doi":"10.1109/APS.1993.385153","DOIUrl":"https://doi.org/10.1109/APS.1993.385153","url":null,"abstract":"The US Air Force Institute of Technology (AFIT) offers a variety of master's degree programs in engineering which cater to the needs of the Air Force. One of the hallmarks of the low observables curriculum is a unique graduate level course entitled \"Radar Cross Section (RCS) Analysis, Measurement, and Reduction.\" The author describes this particular course, and its role in the low observables curriculum. Graduates praise the experience of making their own RCS measurements in AFIT's laboratory as being extremely beneficial in understanding the usefulness and limitations of data presented to them later by government contractors.<<ETX>>","PeriodicalId":138141,"journal":{"name":"Proceedings of IEEE Antennas and Propagation Society International Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131204460","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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