{"title":"Reduced size metallized dielectric resonator antennas","authors":"R. Mongia","doi":"10.1109/APS.1997.625406","DOIUrl":"https://doi.org/10.1109/APS.1997.625406","url":null,"abstract":"Although conventional dielectric resonator antennas (DRAs) are quite small for their use at frequencies about 5 GHz or above, their size (volume and weight) becomes quite excessive at low frequencies around 1 GHz or so. Three novel DRA configurations are described. For these reported configurations which radiate in two different fundamental modes, the frequency of the antennas is nearly independent of the height. The overall size of these antennas is considerably smaller than conventional DRAs and makes them very attractive for applications at low frequencies around 1 GHz. Simplified models for the analysis of resonant frequencies of these antennas are given. Experimental results on the return loss and radiation patterns of a few sample antennas are reported.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129589420","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}
{"title":"Design of a vehicular antenna for GPS/Iridium using a genetic algorithm","authors":"E. Altshuler, D. Linden","doi":"10.1109/APS.1997.631499","DOIUrl":"https://doi.org/10.1109/APS.1997.631499","url":null,"abstract":"We describe an antenna that will operate over the band from about 1225 MHz to 1630 MHz and thus cover both GPS and Iridium frequencies. This antenna radiates nominal right hand circular polarization at elevation angles above about 5/spl deg/ and was designed with a process that uses a genetic algorithm (GA) in conjunction with an electromagnetic code. In this method the beamwidth, VSWR and frequency band are specified and the antenna configuration that most closely produces these characteristics is synthesized.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"76 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127395538","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}
{"title":"Estimation of three-dimensional coherent source positions with a directional borehole radar by MUSIC algorithm","authors":"S. Ebihara, M. Sato, H. Niitsuma","doi":"10.1109/APS.1997.631705","DOIUrl":"https://doi.org/10.1109/APS.1997.631705","url":null,"abstract":"A borehole radar is one form of ground penetrating radars, which operates in a borehole. The significant feature of a borehole radar is its accessibility to targets. Most conventional borehole radar use dipole antennas, which are omnidirectional. However, in many engineering applications, the three-dimensional positions of targets such as fractures and pipes should be accurately determined. We have designed and constructed a prototype broadband directional borehole radar system. The receiver is a conformal array antenna. This radar system operates between 100 and 300 MHz. Since the space available for the array and frequency bandwidth are limited, a super resolution technique should be applied. This paper presents a method for three-dimensional position estimation of coherent broadband sources with the conformal array in a borehole. This method is based on the MUSIC algorithm, and the problem formulation and a decorrelation algorithm are shown. Also, we show experimental results to verify the presented algorithm.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127023529","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}
{"title":"Hybrid MoM/SBR and FEM/SBR methods for scattering by large bodies with inhomogeneous protrusions","authors":"X. Sheng, J. Jin","doi":"10.1109/APS.1997.631543","DOIUrl":"https://doi.org/10.1109/APS.1997.631543","url":null,"abstract":"A hybrid technique was developed for computing scattering by large bodies with cracks and cavities (Jin et al. 1995). This technique employs the shooting and bouncing ray (SBR) method to compute the scattering by large bodies and uses the finite-element method (FEM) to characterize the cracks and cavities. The two methods are combined through a coupling scheme based on the EM equivalence principle and the reciprocity theorem. The coupling scheme is designed in such a manner that it includes all significant interactions between the FEM and the SBR methods and it permits the SBR and FEM computations to be done separately. The resulting technique is efficient and accurate and, because of this, is extended to the calculation of the radiation patterns of conformal antennas in a complex environment (Greenwood et al. 1996). We further extend the hybrid FEM/SBR method and also develop a new hybrid method-of-moments (MoM)/SBR method to compute scattering by large bodies with small protruding scatterers. To be more specific, we first employ the field equivalence principle to replace the protruding scatterers by a set of equivalent electric and magnetic currents. The total scattered field then becomes the superposition of the field scattered by the large body without protrusions, which is calculated using the SBR method, and the field radiated by the equivalent currents in the presence of the large body, which is also calculated using the SBR method with the aid of the reciprocity theorem. The required equivalent currents are computed using the FEM of MoM, which permits the handling of complex material composition of the protrusions.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127471996","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}
{"title":"Synthesis of novel all-dielectric grating filters using genetic algorithms","authors":"C. Zuffada, T. Cwik, C. Ditchman","doi":"10.1109/APS.1997.631498","DOIUrl":"https://doi.org/10.1109/APS.1997.631498","url":null,"abstract":"We are concerned with the design of inhomogeneous, all-dielectric (lossless) periodic structures which act as filters. The problem can be treated as an inverse problem. The authors begin by discussing scattering from a dielectric grating. The theory is used in the design of guided mode resonance filters.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129146189","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}
{"title":"Extension of the compression approach to include the treatment of radiation pattern in the electromagnetic analysis of active planar antennas","authors":"S. Dauguet, R. Gillard, J. Citerne, G. Piton","doi":"10.1109/APS.1997.630069","DOIUrl":"https://doi.org/10.1109/APS.1997.630069","url":null,"abstract":"Developments in planar technologies lead to complex and highly integrated structures in which the coupling becomes increasingly important. In microwave circuits which include active and nonlinear devices, the electromagnetic interaction between the devices and the passive structure significantly influences the circuit performance. This paper presents a compression approach which combines the MPIE solved by a 2.5D method of moment (MOM) for the simulation of the linear structure with the harmonic balance method for the nonlinear analysis. The compression approach is not only used to obtain the power available at each harmonic, but is extended to include the analysis for each harmonic in terms of the radiation pattern. Results for a microstrip antenna using a diode are presented. The diode voltage and current responses in the time domain are compared to those obtained with the commercial circuit analysis software MDS. Finally, the radiation patterns obtained by the extended compression approach are presented for each harmonic.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125652111","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}
{"title":"Propagation of transients in tapered transmission lines with dispersive dielectric media and time-dependent load using FDTD method","authors":"A. Cheldavi","doi":"10.1109/APS.1997.630174","DOIUrl":"https://doi.org/10.1109/APS.1997.630174","url":null,"abstract":"A numerical method to solve the propagation of transient electromagnetic waves in dispersive dielectric media with time-dependent load using FDTD will be presented. The voltage and currents will be computed directly from the Maxwell equation in dispersive dielectric media. The effect of the time-dependent load will be considered as a time-dependent boundary condition. The results of this paper have application in wave propagation in biological media in which besides the dispersive media the boundary conditions may be time-dependent. Finally we give some examples of Gaussian and square pulse propagation in some dispersive tapered lines.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130596373","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}
{"title":"Extending FDTD/convolution techniques to 3-D microwave structures","authors":"S. Hammadi, S. El-Ghazaly","doi":"10.1109/APS.1997.625401","DOIUrl":"https://doi.org/10.1109/APS.1997.625401","url":null,"abstract":"In this paper the simulation of 3D microwave structures using an FDTD/convolution technique, implemented on a massively parallel machine, is presented. This method allows to reduce the computation and memory requirement in the FDTD simulation by replacing large structures with small modules. Validation of this technique is illustrated by comparing the results obtained for a microstrip structure with the results obtained using a conventional FDTD simulation. The new technique is then used to simulate the passive structure used in quasi-optical 2D amplifiers, with the goal to add the active element later on.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130714082","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}
J. Grando, X. Ferrières, P. Levesque, F. Issac, J. Alliot
{"title":"FDTD application to the electrical characterization of materials by solving an inverse problem","authors":"J. Grando, X. Ferrières, P. Levesque, F. Issac, J. Alliot","doi":"10.1109/APS.1997.631690","DOIUrl":"https://doi.org/10.1109/APS.1997.631690","url":null,"abstract":"We present a method in order to obtain the unknown permittivity and conductivity of a homogeneous object. The object is illuminated by an electromagnetic plane wave and we measure a set of near scattered fields with the EMIR (electromagnetic infrared) method. This experimental method is based on the use of photothermic film as a sensor to measure electromagnetic fields. With the field data available, we can formulate an inverse problem to evaluate the electrical characteristics of the studied object. To solve the inverse problem, we use an iterative scheme based on a finite difference time domain method for the direct problem.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130768143","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}
{"title":"Time adaptive time-domain techniques for the design of microwave circuits","authors":"E. Tentzeris, J. Harvey, L. Katehi","doi":"10.1109/APS.1997.631877","DOIUrl":"https://doi.org/10.1109/APS.1997.631877","url":null,"abstract":"The recently developed MRTD schemes are used for the development of a time adaptive time-domain technique for circuit design. The new technique exhibits considerable savings in memory and computational times in comparison to the conventional FDTD scheme.","PeriodicalId":283897,"journal":{"name":"IEEE Antennas and Propagation Society International Symposium 1997. Digest","volume":"80 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132444099","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}