The authors present results of a study involving the design, manufacturing, and test of a large (1.1-m) dichroic subreflector for an offset Cassegrain reflector antenna. The primary focus feed operates at 10.7-11.7 GHz, and the secondary feed operates at 18.1-20.2 GHz, both with linear orthogonal polarizations. A preliminary design of the dichroic structure using an equivalent circuit approach showed that, given the desired closeness of the transmission and reflection bands, double-layer frequency selective surfaces with single resonant elements were the most promising configuration. Two layers of crossed dipoles with an interlayer distance of about 5 mm were selected. Results for electrical performance tests are presented.<>
{"title":"A dichroic subreflector for a communication satellite","authors":"P. Ingvarson, F. Johansson, L. Pettersson","doi":"10.1109/APS.1989.134889","DOIUrl":"https://doi.org/10.1109/APS.1989.134889","url":null,"abstract":"The authors present results of a study involving the design, manufacturing, and test of a large (1.1-m) dichroic subreflector for an offset Cassegrain reflector antenna. The primary focus feed operates at 10.7-11.7 GHz, and the secondary feed operates at 18.1-20.2 GHz, both with linear orthogonal polarizations. A preliminary design of the dichroic structure using an equivalent circuit approach showed that, given the desired closeness of the transmission and reflection bands, double-layer frequency selective surfaces with single resonant elements were the most promising configuration. Two layers of crossed dipoles with an interlayer distance of about 5 mm were selected. Results for electrical performance tests 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":"81982555","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}
High-resolution electromagnetic radar imaging is a process allowing the discrimination of a radar target by studying the location of its scatterers. It is well known that the knowledge of a simple scalar number is not adequate to obtain a satisfactory radar image. The authors propose a polarimetry concept in the radar imaging domain for improving the discrimination of radar targets. Using this concept, it is possible to determine, without acting physically on the antennas, the optimal transmitted and received polarization vector to obtain an optimal radar image, thus allowing better radar target discrimination.<>
{"title":"Polarimetry concept applied to high resolution electromagnetic radar imaging","authors":"E. Pottier, J. Saillard","doi":"10.1109/APS.1989.134963","DOIUrl":"https://doi.org/10.1109/APS.1989.134963","url":null,"abstract":"High-resolution electromagnetic radar imaging is a process allowing the discrimination of a radar target by studying the location of its scatterers. It is well known that the knowledge of a simple scalar number is not adequate to obtain a satisfactory radar image. The authors propose a polarimetry concept in the radar imaging domain for improving the discrimination of radar targets. Using this concept, it is possible to determine, without acting physically on the antennas, the optimal transmitted and received polarization vector to obtain an optimal radar image, thus allowing better radar target discrimination.<<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":"85799241","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 description is given of the modified SMI (sample matrix inversion) adaptive arrays in which the sample covariance matrix is redefined to reduce the effect of thermal noise on the weights of an adaptive array. This is accomplished by subtracting a fraction of the smallest eigenvalue of the original covariance matrix from its diagonal terms. In situations where the number of degrees of freedom of a modified SMI adaptive array is larger than the number of interfering signals incident on the array, the adaptive array provides the required interference suppression. An experimental modified SMI adaptive antenna array is described. Performance results are presented, and the experimental system is a three-element SMI adaptive antenna array and operates in a signal scenario consisting of a desired signal and an interfering signal whose source may be located at an arbitrary angular separation from the desired signal.<>
{"title":"An experimental SMI adaptive antenna array for weak interfering signals","authors":"I. Gupta, R. Dilsavor","doi":"10.1109/APS.1989.135045","DOIUrl":"https://doi.org/10.1109/APS.1989.135045","url":null,"abstract":"A description is given of the modified SMI (sample matrix inversion) adaptive arrays in which the sample covariance matrix is redefined to reduce the effect of thermal noise on the weights of an adaptive array. This is accomplished by subtracting a fraction of the smallest eigenvalue of the original covariance matrix from its diagonal terms. In situations where the number of degrees of freedom of a modified SMI adaptive array is larger than the number of interfering signals incident on the array, the adaptive array provides the required interference suppression. An experimental modified SMI adaptive antenna array is described. Performance results are presented, and the experimental system is a three-element SMI adaptive antenna array and operates in a signal scenario consisting of a desired signal and an interfering signal whose source may be located at an arbitrary angular separation from the desired signal.<<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":"84108102","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 has been demonstrated that the method of successive projections applied to plane wave synthesis yields a fast and effective method for analyzing Fresnel-zone data. In particular, compact range performance can be simulated without the need for a large reflector, at the cost of an increased number of azimuth scans. As an example, for a range length of 320 lambda , 21 scans may be used to achieve a 40- lambda -diameter plane wave region with root-mean-square phase and amplitude errors less than 1 degrees and 0.1 dB, respectively. Such an accurate plane wave is seldom required for normal antenna measurements, and some accuracy may be sacrificed to reduce the number of azimuth scans.<>
{"title":"An alternative plane wave synthesis method for Fresnel-zone antenna measurements","authors":"G. Poulton","doi":"10.1109/APS.1989.134619","DOIUrl":"https://doi.org/10.1109/APS.1989.134619","url":null,"abstract":"It has been demonstrated that the method of successive projections applied to plane wave synthesis yields a fast and effective method for analyzing Fresnel-zone data. In particular, compact range performance can be simulated without the need for a large reflector, at the cost of an increased number of azimuth scans. As an example, for a range length of 320 lambda , 21 scans may be used to achieve a 40- lambda -diameter plane wave region with root-mean-square phase and amplitude errors less than 1 degrees and 0.1 dB, respectively. Such an accurate plane wave is seldom required for normal antenna measurements, and some accuracy may be sacrificed to reduce the number of azimuth scans.<<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":"78265364","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 antenna consisting of a single wire connection from a source to a half-wavelength dipole above a ground plane is studied. With the inherent simplicity of the structure in mind, and the frequent need to connect a dipole antenna to an unbalanced output port (e.g., coaxial or microstrip line), the authors examine the performance of one such antenna and discuss the implications for similar geometry feeds with microstrip patch antennas. Current distribution and radiation patterns are presented. A number of observations on the operation of antennas fed by single wires or probes oriented perpendicular to ground are presented. Although the current distribution on the feed wire appears to be uniform, the description of this wire as a transmission line or nonradiating feed is not correct The mechanism for the radiation from the feed wire is a traveling wave from the feedpoint to the junction with the dipole. Since the resulting radiating structure is asymmetrical, the radiation pattern is also asymmetrical.<>
{"title":"Analysis of the single wire fed dipole antenna","authors":"A. Parfitt, D. Griffin","doi":"10.1109/APS.1989.134961","DOIUrl":"https://doi.org/10.1109/APS.1989.134961","url":null,"abstract":"An antenna consisting of a single wire connection from a source to a half-wavelength dipole above a ground plane is studied. With the inherent simplicity of the structure in mind, and the frequent need to connect a dipole antenna to an unbalanced output port (e.g., coaxial or microstrip line), the authors examine the performance of one such antenna and discuss the implications for similar geometry feeds with microstrip patch antennas. Current distribution and radiation patterns are presented. A number of observations on the operation of antennas fed by single wires or probes oriented perpendicular to ground are presented. Although the current distribution on the feed wire appears to be uniform, the description of this wire as a transmission line or nonradiating feed is not correct The mechanism for the radiation from the feed wire is a traveling wave from the feedpoint to the junction with the dipole. Since the resulting radiating structure is asymmetrical, the radiation pattern is also asymmetrical.<<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":"77913775","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}
TELE-X is a combined direct broadcast and communication satellite, covering the Scandinavian countries. The communication service is intended for high-rate data communication, video conferences, outside broadcasting and high-definition TV transmission. The three TV channels use the 12/18-GHz bands, and the two data/video channels use the 12/14-GHz bands for downline and uplink, respectively. A two-antenna concept with one transmit and one receive antenna was chosen due to the different gain and pointing requirements, the frequency band separation, and in order to avoid passive intermodulation problems. The two basically Cassegrain antenna systems are shaped to enable a circular feed to illuminate the elliptical main reflector efficiently. All the TELE-X antennas have been assembled into an antenna module. Design, integration, and testing are facilitated by the modular approach.<>
{"title":"The antenna system for the TELE-X satellite","authors":"B. Magnus, I. Per","doi":"10.1109/APS.1989.134726","DOIUrl":"https://doi.org/10.1109/APS.1989.134726","url":null,"abstract":"TELE-X is a combined direct broadcast and communication satellite, covering the Scandinavian countries. The communication service is intended for high-rate data communication, video conferences, outside broadcasting and high-definition TV transmission. The three TV channels use the 12/18-GHz bands, and the two data/video channels use the 12/14-GHz bands for downline and uplink, respectively. A two-antenna concept with one transmit and one receive antenna was chosen due to the different gain and pointing requirements, the frequency band separation, and in order to avoid passive intermodulation problems. The two basically Cassegrain antenna systems are shaped to enable a circular feed to illuminate the elliptical main reflector efficiently. All the TELE-X antennas have been assembled into an antenna module. Design, integration, and testing are facilitated by the modular approach.<<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":"72906358","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 conjugate-gradient-fast-Fourier-transform (CG-FFT) scheme to analyze finite dielectric sheets with arbitrary metallization on both sides is used to study microstrip and Vivaldi antennas. The system of integral equations is discretized by expanding the electric and magnetic currents in terms of rooftops and by testing the resulting fields using blade razor functions. The case of a small dipole embedded in a square dielectric sheet of side 0.1 lambda with epsilon = epsilon /sub 0/ is investigated. In addition, a comparison between computed and measured radiation pattern values for a Vivaldi antenna is presented. Discrepancies between the computed and measured values are attributed to the simple numerical model considered for the antenna feeding.<>
{"title":"Analysis of microstrip and Vivaldi antennas using a CG-FFT scheme that allows the study of finite dielectric sheets with arbitrary metallization on both sides","authors":"M. Cátedra, J. Alcaraz","doi":"10.1109/APS.1989.134958","DOIUrl":"https://doi.org/10.1109/APS.1989.134958","url":null,"abstract":"A conjugate-gradient-fast-Fourier-transform (CG-FFT) scheme to analyze finite dielectric sheets with arbitrary metallization on both sides is used to study microstrip and Vivaldi antennas. The system of integral equations is discretized by expanding the electric and magnetic currents in terms of rooftops and by testing the resulting fields using blade razor functions. The case of a small dipole embedded in a square dielectric sheet of side 0.1 lambda with epsilon = epsilon /sub 0/ is investigated. In addition, a comparison between computed and measured radiation pattern values for a Vivaldi antenna is presented. Discrepancies between the computed and measured values are attributed to the simple numerical model considered for the antenna feeding.<<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":"87658841","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 possibility of using a leaky-wave structure as a reception antenna to simultaneously receive emissions from two different satellites is presented. This structure consists of a continuously and longitudinally slotted rectangular waveguide, continuous in its broader wall, illuminating a parabolic cylindrical reflector, with a suitable gain for a satellite transmission link. The transverse response method was used to consider distributed parameters of the equivalent line. The discontinuity is considered to modify the distributed capacitance in part of the equivalent line. By properly dimensioning the structure, an antenna was designed with a double beam, adjustable by the variation of the waveguide physical parameters and with a gain depending upon the reflector.<>
{"title":"Analysis of a reflector antenna with an adjustable double beam","authors":"J.L. Grilo, A. Fernandes","doi":"10.1109/APS.1989.134672","DOIUrl":"https://doi.org/10.1109/APS.1989.134672","url":null,"abstract":"The possibility of using a leaky-wave structure as a reception antenna to simultaneously receive emissions from two different satellites is presented. This structure consists of a continuously and longitudinally slotted rectangular waveguide, continuous in its broader wall, illuminating a parabolic cylindrical reflector, with a suitable gain for a satellite transmission link. The transverse response method was used to consider distributed parameters of the equivalent line. The discontinuity is considered to modify the distributed capacitance in part of the equivalent line. By properly dimensioning the structure, an antenna was designed with a double beam, adjustable by the variation of the waveguide physical parameters and with a gain depending upon the 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":"88407403","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 ring cavity antenna for a wide beamwidth pattern which does not use high-dielectric materials is presented. Antenna characteristics calculated by the cavity model showed that the ring cavity antenna has a wide beamwidth. Theoretical values are also verified by the measured radiation pattern and input impedance.<>
{"title":"A ring cavity antenna of wide beamwidth","authors":"H. Arai, N. Goto","doi":"10.1002/ECJA.4410730811","DOIUrl":"https://doi.org/10.1002/ECJA.4410730811","url":null,"abstract":"A ring cavity antenna for a wide beamwidth pattern which does not use high-dielectric materials is presented. Antenna characteristics calculated by the cavity model showed that the ring cavity antenna has a wide beamwidth. Theoretical values are also verified by the measured radiation pattern and input impedance.<<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":"86340442","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}
120 degrees -sectoral microstrip antenna and mixed boundary semicircular antennas are analyzed using the Green's function approach and segmentation methods. The sectoral microstrip antennas with sectoral angles less than 180 degrees can be used to reduce mutual coupling between elements for the same interelement spacing. The mixed boundary microstrip patch antennas appear very promising for building arrays where mutual coupling between elements can be controlled by having various combinations of electric and magnetic walls for elements. The Green's functions of mixed boundary sectoral elements have been developed using the method of expansion in a series of eigenfunctions. The computed input VSWRs (voltage standing wave ratios) and bandwidths agree well with experimental results. The 120 degrees -sectoral antenna has more bandwidth (3.6%) than the circular antenna (3%) and is smaller in size. The large difference in bandwidths of two mixed boundary semicircular antennas suggests that the straight edges radiate more than the circular edges.<>
{"title":"Mixed boundary semicircular and 120 degrees-sectoral microstrip antennas","authors":"Eswarappa, K. Gupta, R. Raghuram","doi":"10.1109/APS.1989.135055","DOIUrl":"https://doi.org/10.1109/APS.1989.135055","url":null,"abstract":"120 degrees -sectoral microstrip antenna and mixed boundary semicircular antennas are analyzed using the Green's function approach and segmentation methods. The sectoral microstrip antennas with sectoral angles less than 180 degrees can be used to reduce mutual coupling between elements for the same interelement spacing. The mixed boundary microstrip patch antennas appear very promising for building arrays where mutual coupling between elements can be controlled by having various combinations of electric and magnetic walls for elements. The Green's functions of mixed boundary sectoral elements have been developed using the method of expansion in a series of eigenfunctions. The computed input VSWRs (voltage standing wave ratios) and bandwidths agree well with experimental results. The 120 degrees -sectoral antenna has more bandwidth (3.6%) than the circular antenna (3%) and is smaller in size. The large difference in bandwidths of two mixed boundary semicircular antennas suggests that the straight edges radiate more than the circular edges.<<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":"83952048","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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