Using a dyadic Green's function formulation, a rigorous analysis of the two-disk stacked microstrip antenna is performed. Using the vector Hankel transform, the mixed boundary value problem is reduced to a set of coupled vector integral equations. Employing Galerkin's method in the spectral domain, the complex resonant frequencies are calculated as a function of the layered parameters and the ratio of the radii of the two disks. For each mode, the stacked microstrip antenna has dual resonant frequencies associated with the constitutive resonant cavities of the structure.<>
{"title":"Resonant frequencies of stacked circular microstrip antennas","authors":"A. Tulintseff, S.M. Ali, J. Kong","doi":"10.1109/APS.1989.134903","DOIUrl":"https://doi.org/10.1109/APS.1989.134903","url":null,"abstract":"Using a dyadic Green's function formulation, a rigorous analysis of the two-disk stacked microstrip antenna is performed. Using the vector Hankel transform, the mixed boundary value problem is reduced to a set of coupled vector integral equations. Employing Galerkin's method in the spectral domain, the complex resonant frequencies are calculated as a function of the layered parameters and the ratio of the radii of the two disks. For each mode, the stacked microstrip antenna has dual resonant frequencies associated with the constitutive resonant cavities of the structure.<<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":"84100657","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 integral equation solution is obtained by careful application of the moment method and the utilization of the symmetric property. The authors present guidelines that make it possible to avoid redundant computations of the impedance elements and that reduce the computation time as well as the memory space through dedicated matrix computation routines. Computed RCS patterns for a 90 degrees C corner reflector for both vertical and horizontal polarizations are shown and found to compare well with high-frequency predictions and experimental data.<>
{"title":"An integral equation solution for the RCS of large dihedral corner reflectors","authors":"K. Liu, C. Balanis, T. Griesser","doi":"10.1109/APS.1989.134826","DOIUrl":"https://doi.org/10.1109/APS.1989.134826","url":null,"abstract":"An integral equation solution is obtained by careful application of the moment method and the utilization of the symmetric property. The authors present guidelines that make it possible to avoid redundant computations of the impedance elements and that reduce the computation time as well as the memory space through dedicated matrix computation routines. Computed RCS patterns for a 90 degrees C corner reflector for both vertical and horizontal polarizations are shown and found to compare well with high-frequency predictions and experimental data.<<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":"80456728","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 completely shielded dielectric resonator (DR) structure consisting of a DR placed on a dielectric substrate is considered. This configuration is compared with one that has a very-low-dielectric-constant spacer. Particularly, the coupling coefficient between the DR and the microstrip line is analyzed and evaluated by using the mode-matching technique, which is based on dividing the resonator structure into partial regions and regarding them as sections of dielectrically loaded waveguides. The propagation constants are found by solving the resulting transcendental equation by enforcing the continuity of the tangential field components inside each partial region and the condition of vanishing tangential electric field on the metallic enclosure. The numerical evaluation of the coupling is obtained for different DR materials and different substrate thicknesses. The electric field distributions inside the structure with and without the space are also evaluated and compared.<>
{"title":"Analysis of coupling of composite dielectric resonator structure using mode matching technique","authors":"T. Bhattacharjee, X. Tu","doi":"10.1109/APS.1989.134774","DOIUrl":"https://doi.org/10.1109/APS.1989.134774","url":null,"abstract":"A completely shielded dielectric resonator (DR) structure consisting of a DR placed on a dielectric substrate is considered. This configuration is compared with one that has a very-low-dielectric-constant spacer. Particularly, the coupling coefficient between the DR and the microstrip line is analyzed and evaluated by using the mode-matching technique, which is based on dividing the resonator structure into partial regions and regarding them as sections of dielectrically loaded waveguides. The propagation constants are found by solving the resulting transcendental equation by enforcing the continuity of the tangential field components inside each partial region and the condition of vanishing tangential electric field on the metallic enclosure. The numerical evaluation of the coupling is obtained for different DR materials and different substrate thicknesses. The electric field distributions inside the structure with and without the space are also evaluated and compared.<<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":"80660762","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 backing a spiral antenna with a conducting plane reflector narrows the inherent wideband radiation characteristics of the spiral by distorting the current distribution. When a small, circular conducting plane is inserted between the spiral and the plane reflector, the distorted current distribution can be changed to a traveling wave. This traveling-wave current has a decaying amplitude, leading to a desirable radiation beam of good circular polarization. The frequency band for CPW (circularly polarized wave) radiation can be extended from 1:1.18 without the small disk 1:1.42 with the disk.<>
{"title":"Realization of wideband characteristics for a spiral antenna backed by a conducting plane reflector","authors":"H. Nakano, H. Soga","doi":"10.1109/APS.1989.134953","DOIUrl":"https://doi.org/10.1109/APS.1989.134953","url":null,"abstract":"It is shown that backing a spiral antenna with a conducting plane reflector narrows the inherent wideband radiation characteristics of the spiral by distorting the current distribution. When a small, circular conducting plane is inserted between the spiral and the plane reflector, the distorted current distribution can be changed to a traveling wave. This traveling-wave current has a decaying amplitude, leading to a desirable radiation beam of good circular polarization. The frequency band for CPW (circularly polarized wave) radiation can be extended from 1:1.18 without the small disk 1:1.42 with the disk.<<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":"83134821","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 analytical solution for the umbrella reflector surface shape, including the pillowing contribution, is presented. The solution is simple and sufficiently accurate for most antenna applications, and apart from being useful as a design tool, it can be easily incorporated into an existing computer code, allowing for more realistic evaluations of the umbrella reflector electrical characteristics. The analytical solution was tested by numerically solving the equations using a successive overrelaxation procedure. The gain degradation and the gore-related sidelobes clearly show the significance of pillowing on the antenna radiation characteristics.<>
{"title":"Mesh pillow in deployable front-fed umbrella parabolic reflectors","authors":"A. Prata, W. Rusch, R.K. Miller","doi":"10.1109/APS.1989.134664","DOIUrl":"https://doi.org/10.1109/APS.1989.134664","url":null,"abstract":"An analytical solution for the umbrella reflector surface shape, including the pillowing contribution, is presented. The solution is simple and sufficiently accurate for most antenna applications, and apart from being useful as a design tool, it can be easily incorporated into an existing computer code, allowing for more realistic evaluations of the umbrella reflector electrical characteristics. The analytical solution was tested by numerically solving the equations using a successive overrelaxation procedure. The gain degradation and the gore-related sidelobes clearly show the significance of pillowing on the antenna radiation characteristics.<<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":"82491922","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 use of polarimetric radar to detect point targets in a forest clutter environment was evaluated using a truck-mounted L-band polarimetric scatterometer. The polarimetric propagation characteristics of a dense canopy of red pines were measured. A simple polarimetric model was then used to simulate the polarimetric response of other point targets in the same forest environment. The simulation makes it possible to obtain the polarimetric response for a variety of point targets in the same forest environment without the need for detailed polarimetric measurements of each target. Several polarimetric and traditional (amplitude-only) detection schemes were used with the simulated data to evaluate the enhancement in target detection attained with polarimetric techniques as opposed to traditional techniques.<>
{"title":"Polarimetric radar detection of point targets in a forest environment","authors":"M. Whitt, F. Ulaby","doi":"10.1109/APS.1989.134809","DOIUrl":"https://doi.org/10.1109/APS.1989.134809","url":null,"abstract":"The use of polarimetric radar to detect point targets in a forest clutter environment was evaluated using a truck-mounted L-band polarimetric scatterometer. The polarimetric propagation characteristics of a dense canopy of red pines were measured. A simple polarimetric model was then used to simulate the polarimetric response of other point targets in the same forest environment. The simulation makes it possible to obtain the polarimetric response for a variety of point targets in the same forest environment without the need for detailed polarimetric measurements of each target. Several polarimetric and traditional (amplitude-only) detection schemes were used with the simulated data to evaluate the enhancement in target detection attained with polarimetric techniques as opposed to traditional techniques.<<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":"82532615","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 characteristics of centered-inclined, longitudinal/transverse, and compound slot couplers for slot array applications are studied. The variation of normalized resonant length as a function of slot offset and tilt is shown. Both mod S/sub 11/ mod at resonance and the phase of mod S/sub 31/ mod at resonance are shown as functions of offset and tilt.<>
{"title":"Slot couplers for feeding branch waveguides of a planar slot array","authors":"S. Rengarajan","doi":"10.1109/APS.1989.134781","DOIUrl":"https://doi.org/10.1109/APS.1989.134781","url":null,"abstract":"The characteristics of centered-inclined, longitudinal/transverse, and compound slot couplers for slot array applications are studied. The variation of normalized resonant length as a function of slot offset and tilt is shown. Both mod S/sub 11/ mod at resonance and the phase of mod S/sub 31/ mod at resonance are shown as functions of offset and tilt.<<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":"80997388","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 first six TE modes were used to compute the RCS (radar cross section) for a shorted trapezoidal waveguide. It was found that the individual-mode RCS patterns did not agree with measured RCS patterns, and it was necessary to use a combination of modes to obtain satisfactory results. The calculated domain single-mode azimuth-plane RCS and measured RCS were compared. This single-mode calculation underestimates the measured RCS. The measured RCS data, taken over a frequency range of 2 to 18 GHz and an angular range of +/-70 degrees , exhibit fluctuations that indicate phase interference between multiple waveguide modes. Since the precise relative phase between the higher order modes are not usually known, a statistical approach was used to compute a mean RCS and standard deviation. A comparison between the statistically calculated RCS and the fluctuating measured data between 6.75 and 6.95 GHz is shown.<>
{"title":"Scattering by arbitrary-shaped over-moded waveguides","authors":"C. Ryan","doi":"10.1109/APS.1989.134854","DOIUrl":"https://doi.org/10.1109/APS.1989.134854","url":null,"abstract":"The first six TE modes were used to compute the RCS (radar cross section) for a shorted trapezoidal waveguide. It was found that the individual-mode RCS patterns did not agree with measured RCS patterns, and it was necessary to use a combination of modes to obtain satisfactory results. The calculated domain single-mode azimuth-plane RCS and measured RCS were compared. This single-mode calculation underestimates the measured RCS. The measured RCS data, taken over a frequency range of 2 to 18 GHz and an angular range of +/-70 degrees , exhibit fluctuations that indicate phase interference between multiple waveguide modes. Since the precise relative phase between the higher order modes are not usually known, a statistical approach was used to compute a mean RCS and standard deviation. A comparison between the statistically calculated RCS and the fluctuating measured data between 6.75 and 6.95 GHz is shown.<<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":"90449187","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}
Strip elements in a stacked configuration are used to illustrate the improvement in bandwidth over a 45 degrees E-plane scan sector that can be expected from the scan-dependent, double-tuned nature of the configuration. The curves of active resistance versus frequency are shown to have considerable value. The resonant peaks in these curves are shown to arise from individual resonances of single-element arrays, which form the basis for a design procedure. Surface wave resonances are accounted for, but their effect is limited by placing them near the endfire grating lobe frequency. A bandwidth of 1.85 for an E-plane scan from broadside to 45 degrees in a matched configuration has been shown as compared with 1.25 for simple strips. It is conjectured that increased scan and bandwidth would also be achieved by the stacking of rectangular patch elements although the bandwidth would be less than that for strip arrays.<>
{"title":"Strip stacked-element phased arrays","authors":"H. Stalzer, Y. Lubin, A. Hessel, J. Shmoys","doi":"10.1109/APS.1989.134839","DOIUrl":"https://doi.org/10.1109/APS.1989.134839","url":null,"abstract":"Strip elements in a stacked configuration are used to illustrate the improvement in bandwidth over a 45 degrees E-plane scan sector that can be expected from the scan-dependent, double-tuned nature of the configuration. The curves of active resistance versus frequency are shown to have considerable value. The resonant peaks in these curves are shown to arise from individual resonances of single-element arrays, which form the basis for a design procedure. Surface wave resonances are accounted for, but their effect is limited by placing them near the endfire grating lobe frequency. A bandwidth of 1.85 for an E-plane scan from broadside to 45 degrees in a matched configuration has been shown as compared with 1.25 for simple strips. It is conjectured that increased scan and bandwidth would also be achieved by the stacking of rectangular patch elements although the bandwidth would be less than that for strip arrays.<<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":"89967567","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 investigate a new concept in array design, where the level of the grating lobes is controlled by the element pattern. For the array elements circular horns are selected. In standard arrays these horns operate in the TE/sub 11/ mode and beam scanning is achieved fully by element phasing. In the present case, each array element operates in the first two TE/sub 11/ and TE/sub 21/ modes and the element pattern is shaped to place a null in the direction of the grating lobes. Thus, the interelement spacing can be increased beyond that of normal arrays, without a serious pattern degradation due to the appearance of the grating lobes. Also, the array elements in the present study are assumed to be circularly polarized.<>
{"title":"Array thinning in phased arrays using dual mode horns","authors":"H. Ragheb, L. Shafai","doi":"10.1109/APS.1989.134990","DOIUrl":"https://doi.org/10.1109/APS.1989.134990","url":null,"abstract":"The authors investigate a new concept in array design, where the level of the grating lobes is controlled by the element pattern. For the array elements circular horns are selected. In standard arrays these horns operate in the TE/sub 11/ mode and beam scanning is achieved fully by element phasing. In the present case, each array element operates in the first two TE/sub 11/ and TE/sub 21/ modes and the element pattern is shaped to place a null in the direction of the grating lobes. Thus, the interelement spacing can be increased beyond that of normal arrays, without a serious pattern degradation due to the appearance of the grating lobes. Also, the array elements in the present study are assumed to be circularly polarized.<<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":"89481070","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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