The radiation fields of a biconical horn antenna with different flare angles are derived by the use of both the field of an equivalent Huygens source on the aperture and the field of the infinite biconical horn antenna with TEM wave. Numerical and experimental patterns are presented for the symmetrical biconical horn antennas. Numerical and experimental patterns are also shown for the asymmetrical biconical horn antenna such as discone and a coaxial antenna. From the results obtained, it is evident that the method using both the assumption of TEM wave and the equivalent Huygens source can give accurate predictions of the radiation patterns.<>
{"title":"Radiation field of biconical horn antenna with different flare angles","authors":"K. Nagasawa, I. Matsuzuka","doi":"10.1109/APS.1989.134690","DOIUrl":"https://doi.org/10.1109/APS.1989.134690","url":null,"abstract":"The radiation fields of a biconical horn antenna with different flare angles are derived by the use of both the field of an equivalent Huygens source on the aperture and the field of the infinite biconical horn antenna with TEM wave. Numerical and experimental patterns are presented for the symmetrical biconical horn antennas. Numerical and experimental patterns are also shown for the asymmetrical biconical horn antenna such as discone and a coaxial antenna. From the results obtained, it is evident that the method using both the assumption of TEM wave and the equivalent Huygens source can give accurate predictions of the radiation patterns.<<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":"82878271","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 novel method for the analytical determination of the amplitude distribution providing the low sidelobe pattern of conformal array antennas. The proposed projection method considers both the nonuniform element density and element patterns on the aperture. Numerical results are given as well as results of experimental verification for an X-band, half-spherical array with 60 rectangular microstrip antennas.<>
{"title":"A projection method providing low sidelobe pattern in conformal array antennas","authors":"I. Chiba, K. Hariu, S. Sato, S. Mano","doi":"10.1109/APS.1989.134630","DOIUrl":"https://doi.org/10.1109/APS.1989.134630","url":null,"abstract":"The authors present a novel method for the analytical determination of the amplitude distribution providing the low sidelobe pattern of conformal array antennas. The proposed projection method considers both the nonuniform element density and element patterns on the aperture. Numerical results are given as well as results of experimental verification for an X-band, half-spherical array with 60 rectangular microstrip antennas.<<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":"82777576","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}
Formulation, solution, and numerical results are presented for the error estimation of the Fourier-Bessel expansion in the computation of field distribution in coaxial regions. It is shown that there exists an optimal number of terms of the expansion which gives the minimum mean square error. This optimal number of terms is a function of the eigenvalue uncertainties.<>
{"title":"Error estimate of the Fourier-Bessel expansion in computation of field distributions","authors":"Z. Delecki","doi":"10.1109/APS.1989.134600","DOIUrl":"https://doi.org/10.1109/APS.1989.134600","url":null,"abstract":"Formulation, solution, and numerical results are presented for the error estimation of the Fourier-Bessel expansion in the computation of field distribution in coaxial regions. It is shown that there exists an optimal number of terms of the expansion which gives the minimum mean square error. This optimal number of terms is a function of the eigenvalue uncertainties.<<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":"89042955","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 closed-form expression for the total stored energy of an open-ring structure is derived and used to determine the corresponding figure of merit in terms of the antenna gain-bandwidth product. The gain is proportional to the input impedance at resonance R/sub 0/ and the bandwidth is inversely proportional to the total quality factor Q/sub T/ of the antenna. The results for the antenna R/sub 0//Q/sub T/ figure are shown for the TM/sub 11/ mode and the TM/sub 12/ modes. They indicate that different structures can have the same R/sub 0//Q/sub T/ figure.<>
{"title":"The figure of merit of an open-rising microstrip antenna","authors":"M. Sultan","doi":"10.1109/APS.1989.134717","DOIUrl":"https://doi.org/10.1109/APS.1989.134717","url":null,"abstract":"A closed-form expression for the total stored energy of an open-ring structure is derived and used to determine the corresponding figure of merit in terms of the antenna gain-bandwidth product. The gain is proportional to the input impedance at resonance R/sub 0/ and the bandwidth is inversely proportional to the total quality factor Q/sub T/ of the antenna. The results for the antenna R/sub 0//Q/sub T/ figure are shown for the TM/sub 11/ mode and the TM/sub 12/ modes. They indicate that different structures can have the same R/sub 0//Q/sub T/ figure.<<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":"89084868","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 model capable of predicting the effects of mesh electrical contacts on antenna performance by determining the mesh reflection/transmission coefficients. These coefficients can then be used in a diffraction analysis program to determine the reflector's far-field pattern. A generalized method of moment/Floquet expansion technique is used to formulate the problem for an arbitrary mesh cell configuration. Representative numerical results are constructed for contact and no-contact mesh surface models. Results are compared to measured data and good agreement is observed.<>
{"title":"Reflector antennas with mesh surfaces: contact or no contact at wire intersections?","authors":"Y. Rahmat-Samii, W. Imbriale, V. Galindo-Israel","doi":"10.1109/APS.1989.134665","DOIUrl":"https://doi.org/10.1109/APS.1989.134665","url":null,"abstract":"The authors develop a model capable of predicting the effects of mesh electrical contacts on antenna performance by determining the mesh reflection/transmission coefficients. These coefficients can then be used in a diffraction analysis program to determine the reflector's far-field pattern. A generalized method of moment/Floquet expansion technique is used to formulate the problem for an arbitrary mesh cell configuration. Representative numerical results are constructed for contact and no-contact mesh surface models. Results are compared to measured data and good agreement is observed.<<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":"89202588","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}
Summary form only given. It is pointed out that, electromagnetically speaking, a superconductor is distinguishable from a fictitious perfect conductor. A superconducting material is more conveniently treated as a dielectric material with a negative real part of the dielectric constant as far as electromagnetics is concerned. When superconductors are considered as a generalized dielectric material, some superconductive electromagnetic problems are simplified, since the dielectric parameter is an integral part of electromagnetic computation. No technical difficulty is presented to existing computer programs if a dielectric constant passes from a positive value to a negative one. Also presented is a time-domain computational method involving dispersive media, such as superconductors or plasma. It involves a time-domain finite difference approach with system function expansion, so that no explicit convolution is required. It thus greatly reduces memory demand and CPU time. As a consequence of this electromagnetic treatment of a superconductor, the existence of a surface wave on a superconducting surface is also predicted.<>
{"title":"Electromagnetics of superconductors","authors":"K. Mei, G. Liang, T. Van Duzer","doi":"10.1109/APS.1989.134911","DOIUrl":"https://doi.org/10.1109/APS.1989.134911","url":null,"abstract":"Summary form only given. It is pointed out that, electromagnetically speaking, a superconductor is distinguishable from a fictitious perfect conductor. A superconducting material is more conveniently treated as a dielectric material with a negative real part of the dielectric constant as far as electromagnetics is concerned. When superconductors are considered as a generalized dielectric material, some superconductive electromagnetic problems are simplified, since the dielectric parameter is an integral part of electromagnetic computation. No technical difficulty is presented to existing computer programs if a dielectric constant passes from a positive value to a negative one. Also presented is a time-domain computational method involving dispersive media, such as superconductors or plasma. It involves a time-domain finite difference approach with system function expansion, so that no explicit convolution is required. It thus greatly reduces memory demand and CPU time. As a consequence of this electromagnetic treatment of a superconductor, the existence of a surface wave on a superconducting surface is also predicted.<<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":"91406049","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 theory for slot-line antennas is presented that gives satisfactory agreement between theory and measurements. Moreover, it leads to an improved performance with respect to both radiation pattern and gain when compared to former design techniques developed by Prasad and Mahapatra (1983) and Abdel-Azis et al. (1984). The design procedure for a prescribed radiation characteristic optimizes the beamwidth for a certain sidelobe level. The antenna gain is relatively high and varies within a small range for the desired frequency band. The design method has been applied to both X-band and Ka-band antennas.<>
{"title":"Design of slot line antennas","authors":"Ahmed O. A. A. Elnor, A. Omar","doi":"10.1109/APS.1989.135003","DOIUrl":"https://doi.org/10.1109/APS.1989.135003","url":null,"abstract":"A design theory for slot-line antennas is presented that gives satisfactory agreement between theory and measurements. Moreover, it leads to an improved performance with respect to both radiation pattern and gain when compared to former design techniques developed by Prasad and Mahapatra (1983) and Abdel-Azis et al. (1984). The design procedure for a prescribed radiation characteristic optimizes the beamwidth for a certain sidelobe level. The antenna gain is relatively high and varies within a small range for the desired frequency band. The design method has been applied to both X-band and Ka-band antennas.<<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":"81043525","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 way to improve the ill-posedness of inverse scattering problems by making the cell size of the discretization much larger is proposed. In order to see the effect of the larger cell discretization, a 24-cell structure (0.1 lambda *0.1 lambda ) is divided into 4 large cells (0.1 lambda *0.6 lambda ). Step and continuous permittivity profiles are reconstructed by the 24-cell discretization and the 4-cell discretization, respectively, for X/sub 0/=0.3 lambda . The 4-cell discretization gives a result very close to the original dielectric profile, but the computation time is reduced significantly compared to the 24-cell inversion since the number of unknowns for 4-cell discretization is reduced to 12 from 24.<>
{"title":"Electromagnetic imaging of permittivity profiles by an improved spectral inverse technique","authors":"Hyun-Chulchoi, Se-Yun Kim, J. Ra","doi":"10.1109/APS.1989.134623","DOIUrl":"https://doi.org/10.1109/APS.1989.134623","url":null,"abstract":"A way to improve the ill-posedness of inverse scattering problems by making the cell size of the discretization much larger is proposed. In order to see the effect of the larger cell discretization, a 24-cell structure (0.1 lambda *0.1 lambda ) is divided into 4 large cells (0.1 lambda *0.6 lambda ). Step and continuous permittivity profiles are reconstructed by the 24-cell discretization and the 4-cell discretization, respectively, for X/sub 0/=0.3 lambda . The 4-cell discretization gives a result very close to the original dielectric profile, but the computation time is reduced significantly compared to the 24-cell inversion since the number of unknowns for 4-cell discretization is reduced to 12 from 24.<<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":"88753496","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 dispersion of a Rotman lens is quantified by the distortion that a particular Rotman lens would introduce into various pulses. The lens is characterized by broadband measurement of its transfer function. Then this function is numerically applied to the spectrum of a simulated pulse. Aside from a few complications, the resulting function is the Fourier transform of the distorted pulse. It is concluded that, although the Rotman lens is a true time-delay device, practical implementations exhibit dispersion that can be characterized by the method described. The dispersion produces distortion that is probably not significant except in spread-spectrum pulses. For chirped pulses, amplitude distortion may be significant, but it can likely be reduced carefully designing the lens to avoid mismatch reflections.<>
{"title":"Characterization of the dispersion of a Rotman lens","authors":"V. Tripp, J. Tehan, C. W. White","doi":"10.1109/APS.1989.134776","DOIUrl":"https://doi.org/10.1109/APS.1989.134776","url":null,"abstract":"The dispersion of a Rotman lens is quantified by the distortion that a particular Rotman lens would introduce into various pulses. The lens is characterized by broadband measurement of its transfer function. Then this function is numerically applied to the spectrum of a simulated pulse. Aside from a few complications, the resulting function is the Fourier transform of the distorted pulse. It is concluded that, although the Rotman lens is a true time-delay device, practical implementations exhibit dispersion that can be characterized by the method described. The dispersion produces distortion that is probably not significant except in spread-spectrum pulses. For chirped pulses, amplitude distortion may be significant, but it can likely be reduced carefully designing the lens to avoid mismatch reflections.<<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":"85258604","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 observed geodesic splitting in the case of surface ray propagation over a general paraboloid of revolution (GPOR). Since even the primary geodesics are split in both clockwise and counterclockwise directions, this leads to a double of the ray paths to be considered in antenna characteristics computations. The authors provide an insight into the ray-splitting phenomenon for the simplest (i.e. lowest order) possible convex surface. It is noted that, in general, the ray tracing over a GPOR would require a bivariate search. The ray splitting in the case of the GPOR tends to further increase the computer time required for the determination of the surface ray geometric parameters. The authors have developed a geodesic constant method (GCM) involving an accurate simple univariate search which has brought the electromagnetic field computations within the ambit of tractability.<>
{"title":"Geodesic splitting on general paraboloid of revolution and its implications to the surface ray analysis","authors":"R. Jha, S. Bokhari, V. Sudhakar, P. Mahapatra","doi":"10.1109/APS.1989.134648","DOIUrl":"https://doi.org/10.1109/APS.1989.134648","url":null,"abstract":"The authors have observed geodesic splitting in the case of surface ray propagation over a general paraboloid of revolution (GPOR). Since even the primary geodesics are split in both clockwise and counterclockwise directions, this leads to a double of the ray paths to be considered in antenna characteristics computations. The authors provide an insight into the ray-splitting phenomenon for the simplest (i.e. lowest order) possible convex surface. It is noted that, in general, the ray tracing over a GPOR would require a bivariate search. The ray splitting in the case of the GPOR tends to further increase the computer time required for the determination of the surface ray geometric parameters. The authors have developed a geodesic constant method (GCM) involving an accurate simple univariate search which has brought the electromagnetic field computations within the ambit of tractability.<<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":"90666430","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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