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":"56 1","pages":"296-299 vol.1"},"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}
An accurate and reliable electromagnetic model has been developed for the design of a circular polarizer in a coaxial waveguide. The component consists of a coaxial waveguide loaded by irises with inductive and capacitive behaviors for the incident field. The design is based on the method of field expansion into eigenmodes and takes into account the effects of higher order mode interactions and of multiple reflections among the polarizer elements. The measured and computed performances of a very compact five-element feasibility breadboard are presented. An axial ratio better than 1.02, insertion losses lower than 0.1 dB, and return losses better than 27 dB have been obtained over a 13.5% frequency band.<>
{"title":"An iris polarizer in coaxial waveguide","authors":"G. Figlia, D. Forigo, F. Mercurio, D. Savini","doi":"10.1109/APS.1989.134856","DOIUrl":"https://doi.org/10.1109/APS.1989.134856","url":null,"abstract":"An accurate and reliable electromagnetic model has been developed for the design of a circular polarizer in a coaxial waveguide. The component consists of a coaxial waveguide loaded by irises with inductive and capacitive behaviors for the incident field. The design is based on the method of field expansion into eigenmodes and takes into account the effects of higher order mode interactions and of multiple reflections among the polarizer elements. The measured and computed performances of a very compact five-element feasibility breadboard are presented. An axial ratio better than 1.02, insertion losses lower than 0.1 dB, and return losses better than 27 dB have been obtained over a 13.5% frequency band.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"13 1","pages":"961-964 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73224887","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 preliminary model for the lump-loaded FSS (frequency selective surface) using simple representations for the lumped elements and their interconnections. The representations are derived by applying the resistive boundary condition to include a general surface impedance in the problem formulation. The surface impedance term is then incorporated in the method-of-moments solution and can be varied in each subdomain. A simple lumped-element model is obtained by considering a surface with this type of varying surface impedance to represent the loading. Comparisons of the surface and lumped-load formulations when applied to a four-legged element are shown.<>
{"title":"The study of FSS surfaces with varying surface impedance and lumped elements","authors":"L. Epp, C. Chan, R. Mittra","doi":"10.1109/APS.1989.134882","DOIUrl":"https://doi.org/10.1109/APS.1989.134882","url":null,"abstract":"The authors develop a preliminary model for the lump-loaded FSS (frequency selective surface) using simple representations for the lumped elements and their interconnections. The representations are derived by applying the resistive boundary condition to include a general surface impedance in the problem formulation. The surface impedance term is then incorporated in the method-of-moments solution and can be varied in each subdomain. A simple lumped-element model is obtained by considering a surface with this type of varying surface impedance to represent the loading. Comparisons of the surface and lumped-load formulations when applied to a four-legged element are shown.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"134 1","pages":"1056-1059 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73782909","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 scattering properties of targets composed of cylinders and disks of various sizes and complex composition are investigated both experimentally and theoretically. In particular, the two components of the backscattered fields from these targets are measured in both amplitude and relative phase, yielding the polarization scattering matrix, referred to circular base vectors at X-band. Numerically, the scattering problem is formulated in terms of the equivalent currents on the surface of the scatterers, leading to a set of integral equations which are solved using the method of moments. The approach is flexible, as it can be applied to scatterers of varying sizes, shapes, and material composition. Results are presented for targets of complex composition, particularly with surfaces that are partially dielectric and partially metallic, and of various sizes and dimensional ratios around the resonance region.<>
{"title":"The scattering of electromagnetic waves from targets with composite dielectric and metallic surfaces","authors":"Y. Antar, A. Kishk","doi":"10.1109/APS.1989.134798","DOIUrl":"https://doi.org/10.1109/APS.1989.134798","url":null,"abstract":"The scattering properties of targets composed of cylinders and disks of various sizes and complex composition are investigated both experimentally and theoretically. In particular, the two components of the backscattered fields from these targets are measured in both amplitude and relative phase, yielding the polarization scattering matrix, referred to circular base vectors at X-band. Numerically, the scattering problem is formulated in terms of the equivalent currents on the surface of the scatterers, leading to a set of integral equations which are solved using the method of moments. The approach is flexible, as it can be applied to scatterers of varying sizes, shapes, and material composition. Results are presented for targets of complex composition, particularly with surfaces that are partially dielectric and partially metallic, and of various sizes and dimensional ratios around the resonance region.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"51 1","pages":"750-753 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75070875","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 boundary integral equation method for the analysis of stripline and microstrip lenses is presented. The field distributions across the port apertures surrounding the lens's cavity are described by a contour integral that satisfies the wave equation in the planar lens cavity. All mutual couplings and hence internal reflections between ports are taken into account. The model is used to predict the performance of a nonoptimal Rotman lens with 8 input ports and 20 output ports. There is a good agreement with the measured results for both port coupling and match.<>
{"title":"Planar waveguide model of Rotman lens","authors":"K.K. Chan","doi":"10.1109/APS.1989.134772","DOIUrl":"https://doi.org/10.1109/APS.1989.134772","url":null,"abstract":"A boundary integral equation method for the analysis of stripline and microstrip lenses is presented. The field distributions across the port apertures surrounding the lens's cavity are described by a contour integral that satisfies the wave equation in the planar lens cavity. All mutual couplings and hence internal reflections between ports are taken into account. The model is used to predict the performance of a nonoptimal Rotman lens with 8 input ports and 20 output ports. There is a good agreement with the measured results for both port coupling and match.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"78 1","pages":"651-654 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74031341","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 describe the variational and Fourier analyses for gain enhancement and input characteristics of infinite and finite dielectric loaded antennas with an infinite ground plane. They derive the variational expressions for the input characteristics in two cases of dielectric loaded antennas, a waveguide aperture, and a current element or patch excited by a coaxial line.<>
{"title":"Variational analysis for gain enhancement and input characteristics of dielectric loaded antennas","authors":"Y. Sugio, T. Makimoto, T. Tsugawa","doi":"10.1109/APS.1989.134967","DOIUrl":"https://doi.org/10.1109/APS.1989.134967","url":null,"abstract":"The authors describe the variational and Fourier analyses for gain enhancement and input characteristics of infinite and finite dielectric loaded antennas with an infinite ground plane. They derive the variational expressions for the input characteristics in two cases of dielectric loaded antennas, a waveguide aperture, and a current element or patch excited by a coaxial line.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"519 1","pages":"1364-1367 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77190066","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 corner diffraction formula is derived by evaluating asymptotically the radiation integral using the equivalent edge current. Unlike the original equivalent current method, the equivalent edge current used here is in terms of the uniform general theory of diffraction (GTD) instead of Keller's GTD, and the result is uniformly continuous through the entire far-field region. A computation example is given to confirm the validity of the formula. A 1/4 lambda monopole located at the center of a square perfectly conducting plate was considered. Both in the diagonal plane and in the y-z plane, good agreement of the computed pattern with the measured one was achieved.<>
{"title":"A corner diffraction formula","authors":"X. Zhang, N. Inagaki, N. Kikuma","doi":"10.1109/APS.1989.134947","DOIUrl":"https://doi.org/10.1109/APS.1989.134947","url":null,"abstract":"A corner diffraction formula is derived by evaluating asymptotically the radiation integral using the equivalent edge current. Unlike the original equivalent current method, the equivalent edge current used here is in terms of the uniform general theory of diffraction (GTD) instead of Keller's GTD, and the result is uniformly continuous through the entire far-field region. A computation example is given to confirm the validity of the formula. A 1/4 lambda monopole located at the center of a square perfectly conducting plate was considered. Both in the diagonal plane and in the y-z plane, good agreement of the computed pattern with the measured one was achieved.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"273 1","pages":"1290-1293 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76191089","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}
H. Zebker, D. Held, J. V. Zyl, P. Dubois, L. Norikane
The authors derive an algorithm to reduce required storage space for multipolarimetric synthetic aperture radar data which preserves signal integrity. The data reduction operation reduces the required storage by 12.8. The image synthesis process applied to a reduced data set can be applied to a standard image in two minutes on a VAX 785 when the compressed data format is used. This is ten times faster than image synthesis of the corresponding original data, due to the smaller volume of the compressed data (10 Mb compared with 128 Mb per image). The errors introduced in the output images are on the order of 10/sup -3/. Thus, operations with polarimetric data are greatly facilitated and are now within reach of small research groups.<>
{"title":"Data volume reduction for imaging radar polarimeter","authors":"H. Zebker, D. Held, J. V. Zyl, P. Dubois, L. Norikane","doi":"10.1109/APS.1989.134964","DOIUrl":"https://doi.org/10.1109/APS.1989.134964","url":null,"abstract":"The authors derive an algorithm to reduce required storage space for multipolarimetric synthetic aperture radar data which preserves signal integrity. The data reduction operation reduces the required storage by 12.8. The image synthesis process applied to a reduced data set can be applied to a standard image in two minutes on a VAX 785 when the compressed data format is used. This is ten times faster than image synthesis of the corresponding original data, due to the smaller volume of the compressed data (10 Mb compared with 128 Mb per image). The errors introduced in the output images are on the order of 10/sup -3/. Thus, operations with polarimetric data are greatly facilitated and are now within reach of small research groups.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"11 1","pages":"1354-1357 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74364951","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 that by using the BEM (boundary-element method), it is possible to compute the whole-angle radiation patterns of offset cylindrical reflector antennas with aperture blockage. Consideration is given to a circular cylinder loaded near the aperture of a small offset cylindrical reflector antenna as the blocking model. The overall radiation patterns, including the strut-scattering effects, are predicted by using the BEM and compared with measured patterns (at a frequency of 8 GHz) for verification. Although there appears to be some differences of levels at some wide-angle regions (due probably to a misalignment or measuring setup errors), the entire radiation pattern is found to be well predicted by the numerical data, thus proving the validity of the method.<>
{"title":"An overall azimuthal pattern computation of blocked cylindrical reflector antennas","authors":"K. Miyata, I. Fukai","doi":"10.1109/APS.1989.134922","DOIUrl":"https://doi.org/10.1109/APS.1989.134922","url":null,"abstract":"It is shown that by using the BEM (boundary-element method), it is possible to compute the whole-angle radiation patterns of offset cylindrical reflector antennas with aperture blockage. Consideration is given to a circular cylinder loaded near the aperture of a small offset cylindrical reflector antenna as the blocking model. The overall radiation patterns, including the strut-scattering effects, are predicted by using the BEM and compared with measured patterns (at a frequency of 8 GHz) for verification. Although there appears to be some differences of levels at some wide-angle regions (due probably to a misalignment or measuring setup errors), the entire radiation pattern is found to be well predicted by the numerical data, thus proving the validity of the method.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"31 1","pages":"1195-1198 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75767744","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 low-loss high-quality dielectric material that can be used in space antennas. A 7.5 degrees semi-flare angle dielectric-loaded horn is shown. The dielectric material is placed against the thin-wall metal cone of the horn and a thin layer of Left Koweld glue is used in the gap. Experimental E- and H-plane patterns of the horn antenna at 15.3 GHz are shown. The peak cross-polarization level is better than -40 dB at 6.84, 10.68, 18.7, 23.8, 36.5, and 90 GHz. Computed copolar footprints of a typical radiometer antenna using the dielectric-loaded horn feed are shown.<>
{"title":"Dielectric-loaded horn feeds for radiometer antenna","authors":"A. Kumar","doi":"10.1109/APS.1989.134984","DOIUrl":"https://doi.org/10.1109/APS.1989.134984","url":null,"abstract":"The authors have developed a low-loss high-quality dielectric material that can be used in space antennas. A 7.5 degrees semi-flare angle dielectric-loaded horn is shown. The dielectric material is placed against the thin-wall metal cone of the horn and a thin layer of Left Koweld glue is used in the gap. Experimental E- and H-plane patterns of the horn antenna at 15.3 GHz are shown. The peak cross-polarization level is better than -40 dB at 6.84, 10.68, 18.7, 23.8, 36.5, and 90 GHz. Computed copolar footprints of a typical radiometer antenna using the dielectric-loaded horn feed are shown.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"8 1","pages":"1424-1426 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79972462","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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