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":"2016 1","pages":"876-876(c) vol.2"},"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}
Describes a numerical optimization procedure based on the Powell (1965) nonlinear regression algorithm for measuring the complex dielectric constant of radome composite materials and coatings at millimeter wavelengths using free-space measurements of the transmission coefficient over a range of incidence angles and frequencies. Radomes usually need rain-erosion, antistatic, and hydrophobic coatings for environmental protection. In the present approach, the determination of the permittivity of these thin radome coatings is achieved by depositing the coating on a substrate of known dielectric constant and analyzing the transmission coefficient of the two-layer medium. Since the regression algorithm is used to analyze a large number of data points, it reduces the random errors in the experiments and yields more accurate information than the single-point free-space measurement methods used by other authors at millimeter wavelengths. The validity and accuracy of this technique were confirmed by making measurements on standard dielectrics such as polyethylene, nylon, and Teflon.<>
{"title":"Free-space millimeter-wave measurement of the complex dielectric constant of radome materials using nonlinear least-squares analysis","authors":"B. R. Rao","doi":"10.1109/APS.1989.135014","DOIUrl":"https://doi.org/10.1109/APS.1989.135014","url":null,"abstract":"Describes a numerical optimization procedure based on the Powell (1965) nonlinear regression algorithm for measuring the complex dielectric constant of radome composite materials and coatings at millimeter wavelengths using free-space measurements of the transmission coefficient over a range of incidence angles and frequencies. Radomes usually need rain-erosion, antistatic, and hydrophobic coatings for environmental protection. In the present approach, the determination of the permittivity of these thin radome coatings is achieved by depositing the coating on a substrate of known dielectric constant and analyzing the transmission coefficient of the two-layer medium. Since the regression algorithm is used to analyze a large number of data points, it reduces the random errors in the experiments and yields more accurate information than the single-point free-space measurement methods used by other authors at millimeter wavelengths. The validity and accuracy of this technique were confirmed by making measurements on standard dielectrics such as polyethylene, nylon, and Teflon.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"11 1","pages":"1534-1537 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78359467","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 efficient method is developed for the study of a grid of hexagonal meshes. An efficient grid of hexagonal meshes is envisaged where four-wire crosses in a rectangular mesh are replaced by symmetrical three-wire stars. After the current of a wire grid has been enumerated, the scattered field can be determined. The transmission through the screen or the reflection from the screen can then be evaluated by adding the incident field and the scattered field. Pictures illustrating the hexagonal-mesh grid are shown.<>
{"title":"Scattering of electromagnetic waves by a wire grid of hexagonal meshes","authors":"E. Yung, C. Cheng","doi":"10.1109/APS.1989.134793","DOIUrl":"https://doi.org/10.1109/APS.1989.134793","url":null,"abstract":"An efficient method is developed for the study of a grid of hexagonal meshes. An efficient grid of hexagonal meshes is envisaged where four-wire crosses in a rectangular mesh are replaced by symmetrical three-wire stars. After the current of a wire grid has been enumerated, the scattered field can be determined. The transmission through the screen or the reflection from the screen can then be evaluated by adding the incident field and the scattered field. Pictures illustrating the hexagonal-mesh grid are shown.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"41 1","pages":"730-733 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78675025","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 shaped reflector antenna, illuminated by a corrugated horn, has been designed, fabricated, and tested. The test results show that the feed blockage and the strut support blockage cause performance degradation. The deficiency can be corrected by using a shaped lens, illuminated by a corrugated horn. The lens antenna avoids both the feed and the strut blockage. The lens surface is shaped to provide a nearly uniform coverage over a +or-90 degrees cone. A good axial ratio at 44 GHz is achieved by designing the corrugated horn with nearly equal E- and H-plane patterns.<>
{"title":"An EHF omnidirectional lens antenna","authors":"E. Lee, Y. Hwang","doi":"10.1109/APS.1989.135034","DOIUrl":"https://doi.org/10.1109/APS.1989.135034","url":null,"abstract":"A shaped reflector antenna, illuminated by a corrugated horn, has been designed, fabricated, and tested. The test results show that the feed blockage and the strut support blockage cause performance degradation. The deficiency can be corrected by using a shaped lens, illuminated by a corrugated horn. The lens antenna avoids both the feed and the strut blockage. The lens surface is shaped to provide a nearly uniform coverage over a +or-90 degrees cone. A good axial ratio at 44 GHz is achieved by designing the corrugated horn with nearly equal E- and H-plane patterns.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"1 1","pages":"1610-1613 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90167816","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":"74 1","pages":"1654-1657 vol.3"},"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}
Designing horn clusters for contoured beam antennas on board satellites (e.g. the ATLANTIS antenna) requires an accurate simulation of the copolar and cross-polar components of their field patterns. This simulation should include mutual couplings between horns and a suitable modeling of the horns' surroundings. The field pattern obtained with conical horns that open in a finite metallic plate is presented and compared with measurements. The proposed model uses a numerical integration procedure to calculate the mutual coupling between the different horn modes and to compute the radiated patterns and GTD to include the finite plate. This procedure makes it possible to analyze any type of horn (with analytic modes) placed on a conducting plate which is either polygonal or circular. The results obtained using cylindrical horns provide a better prediction than does a simple model without GTD.<>
{"title":"Aperture radiation analysis including plane finiteness and mutual coupling","authors":"L. de Haro, J. Besada","doi":"10.1109/APS.1989.135024","DOIUrl":"https://doi.org/10.1109/APS.1989.135024","url":null,"abstract":"Designing horn clusters for contoured beam antennas on board satellites (e.g. the ATLANTIS antenna) requires an accurate simulation of the copolar and cross-polar components of their field patterns. This simulation should include mutual couplings between horns and a suitable modeling of the horns' surroundings. The field pattern obtained with conical horns that open in a finite metallic plate is presented and compared with measurements. The proposed model uses a numerical integration procedure to calculate the mutual coupling between the different horn modes and to compute the radiated patterns and GTD to include the finite plate. This procedure makes it possible to analyze any type of horn (with analytic modes) placed on a conducting plate which is either polygonal or circular. The results obtained using cylindrical horns provide a better prediction than does a simple model without GTD.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"63 1","pages":"1572-1575 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78820731","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 application of diffraction theory to an impressed electric field on a linear cylindrical antenna is considered. It is shown that, physically, the impressed field on the antenna is the result of a diffraction of the driving field from the gap to the antenna surface and can be found by the methods of diffraction theory. The equation for the impressed field on a zero-gap antenna is reexamined. It is found that the impressed field on a zero-gap antenna is concentrated on a narrow strip on the order of the antenna radius. On the other hand, inside the strip the impressed field is inversely proportional to the antenna radius.<>
{"title":"An impressed field on a linear antenna: the diffraction theory","authors":"G. Nedlin","doi":"10.1109/APS.1989.134693","DOIUrl":"https://doi.org/10.1109/APS.1989.134693","url":null,"abstract":"The application of diffraction theory to an impressed electric field on a linear cylindrical antenna is considered. It is shown that, physically, the impressed field on the antenna is the result of a diffraction of the driving field from the gap to the antenna surface and can be found by the methods of diffraction theory. The equation for the impressed field on a zero-gap antenna is reexamined. It is found that the impressed field on a zero-gap antenna is concentrated on a narrow strip on the order of the antenna radius. On the other hand, inside the strip the impressed field is inversely proportional to the antenna radius.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"90 1","pages":"360-362 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85650466","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 localized temperature distribution inside a biological material (human muscle) is obtained through the use of a parabolic reflector to focus an electromagnetic pulse. With the point-matched time-domain finite-element method, the focused field and its penetration into the biological material are found, then the temperature profile in the material is calculated. The temperature is localized so that it can heat a specific spot without overburning the surrounding tissue. Attention is given to the factors which influence the localization characteristics, including the applied frequency, the associated electric parameters of the biological material, and the size of the parabolic reflector. The penetration depth and localization volume can be controlled by the adjustment of the applied frequency and the parameters of the reflector.<>
{"title":"Penetration of a focused electromagnetic pulse into a biological material and its application to hyperthermia","authors":"H. Chang, K. Mei","doi":"10.1109/APS.1989.134742","DOIUrl":"https://doi.org/10.1109/APS.1989.134742","url":null,"abstract":"A localized temperature distribution inside a biological material (human muscle) is obtained through the use of a parabolic reflector to focus an electromagnetic pulse. With the point-matched time-domain finite-element method, the focused field and its penetration into the biological material are found, then the temperature profile in the material is calculated. The temperature is localized so that it can heat a specific spot without overburning the surrounding tissue. Attention is given to the factors which influence the localization characteristics, including the applied frequency, the associated electric parameters of the biological material, and the size of the parabolic reflector. The penetration depth and localization volume can be controlled by the adjustment of the applied frequency and the parameters of the reflector.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"61 1","pages":"544-547 vol.1"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85656299","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 linearly tapered slot antenna (LTSA) is an endfire radiator formed by a tapered slotline that is usually supported on a thin, low- epsilon /sub r/ substrate. K.S. Yngvesson et al. (1985) have studied the radiation characteristics of LTSAs that are optimized for use in the focal plane of imaging/multiple-beam systems having f/D in the range of 1 to 2. In the present work, the author presents the results of an experimental investigation of the radiation properties of antennas with wider beamwidths. Some data on narrow-beamwidth antennas are included. Particular emphasis is placed on polarization in the intercardinal planes, where high levels of cross-polarization are observed. The study was conducted by fabricating four antennas on 30-mil Duroid ( epsilon /sub r/=2.2). In addition, two antennas were fabricated from 3-mil shim stock and supported by a styrofoam bridge to create antennas with air dielectric. It is concluded that the LTSA has many advantageous characteristics, and it is compatible with printed-circuit feed networks. However, designers should be aware of its polarization properties, which could adversely affect system performance.<>
{"title":"Radiation characteristics of linearly tapered slot antennas","authors":"D. Schaubert","doi":"10.1109/APS.1989.134956","DOIUrl":"https://doi.org/10.1109/APS.1989.134956","url":null,"abstract":"The linearly tapered slot antenna (LTSA) is an endfire radiator formed by a tapered slotline that is usually supported on a thin, low- epsilon /sub r/ substrate. K.S. Yngvesson et al. (1985) have studied the radiation characteristics of LTSAs that are optimized for use in the focal plane of imaging/multiple-beam systems having f/D in the range of 1 to 2. In the present work, the author presents the results of an experimental investigation of the radiation properties of antennas with wider beamwidths. Some data on narrow-beamwidth antennas are included. Particular emphasis is placed on polarization in the intercardinal planes, where high levels of cross-polarization are observed. The study was conducted by fabricating four antennas on 30-mil Duroid ( epsilon /sub r/=2.2). In addition, two antennas were fabricated from 3-mil shim stock and supported by a styrofoam bridge to create antennas with air dielectric. It is concluded that the LTSA has many advantageous characteristics, and it is compatible with printed-circuit feed networks. However, designers should be aware of its polarization properties, which could adversely affect system performance.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"30 1","pages":"1324-1327 vol.3"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83284791","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}
Vezzosi (Ann. des Telecommun., vol.37, p.425-39, Sept. 1982) proposed an eigenvector (EV) rotation method to resolve multiple signal arrivals to a sensor array and to estimate their angles-of arrival. In the present work it is shown that the model assumed by Vezzosi implies uncorrelated sources, and that the criterion by which the EV rotation is carried out is based on this implicit assumption. The authors present simulation results demonstrating the behavior of the method in a correlated two-source environment with various magnitudes of correlation coefficient, and they show the dependence of the quality of the estimates on the phase of the correlation coefficient. It is concluded that Vezzosi's method is very effective for resolving uncorrelated arrivals. However, it will encounter problems when the arrivals are partly correlated.<>
{"title":"On the limitation of Vezzosi's subspace rotation method for angle-of-arrival estimation","authors":"F. Haber, Q. Shi","doi":"10.1109/APS.1989.134865","DOIUrl":"https://doi.org/10.1109/APS.1989.134865","url":null,"abstract":"Vezzosi (Ann. des Telecommun., vol.37, p.425-39, Sept. 1982) proposed an eigenvector (EV) rotation method to resolve multiple signal arrivals to a sensor array and to estimate their angles-of arrival. In the present work it is shown that the model assumed by Vezzosi implies uncorrelated sources, and that the criterion by which the EV rotation is carried out is based on this implicit assumption. The authors present simulation results demonstrating the behavior of the method in a correlated two-source environment with various magnitudes of correlation coefficient, and they show the dependence of the quality of the estimates on the phase of the correlation coefficient. It is concluded that Vezzosi's method is very effective for resolving uncorrelated arrivals. However, it will encounter problems when the arrivals are partly correlated.<<ETX>>","PeriodicalId":11330,"journal":{"name":"Digest on Antennas and Propagation Society International Symposium","volume":"20 1","pages":"992-995 vol.2"},"PeriodicalIF":0.0,"publicationDate":"1989-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87435343","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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