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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An?lise de superf?cies seletivas de freq??ncia atrav?s do m?todo dos potenciais vetorias de Hertz

Gomes Neto, Milton Luciano Cavalcante 06 April 2004 (has links)
Made available in DSpace on 2014-12-17T14:55:23Z (GMT). No. of bitstreams: 1 MiltonLCGN_Capa_ate_pag14.pdf: 8498531 bytes, checksum: 98bb761f871446c2506a2971dd59c5eb (MD5) Previous issue date: 2004-04-06 / This work presents a theoretical and numerical analysis of Frequency Selective Surfaces (FSS) with elements as rectangular patch, thin dipole and crossed dipole mounted on uniaxial anisotropic dielectric substrate layers for orientations of the optical axis along x, y and z directions. The analysis of these structures is accomplished by combination of the Hertz vector potentials method and the Galerkin's technique, in the Fourier transform-domain, using entire?domain basis functions. This study consists in the use of one more technique for analysis of FSS on anisotropic dielectric substrate. And presents as the main contribution the introduction of one more project parameter to determinate the transmission and reflection characteristics of periodic structures, from the use of anisotropic dielectric with orientations of the crystal optical axis along x, y and z directions. To validate this analysis, the numerical results of this work are compared to those obtained by other authors, for FSS structures on anisotropic and isotropic dielectric substrates. Also are compared experimental results and the numerical correspondent ones for the FSS isotropic case. The technique proposed in this work is accurate and efficient. ln a second moment, curves are presented for the transmission and reflection characteristics of the FSS structures using conducting patch elements mounted on uniaxial anisotropic dielectric substrate layers with optical axis oriented along x, y and z directions. From analysis of these curves, the performance of the considered FSS structures as function of the optical axis orientation is described / Este trabalho apresneta uma an?lise te?rica e num?rica de superf?cies seletivas de freq??ncia, ou Frequency Secective Surface (FSS) com elementos do tipo patch retangular, dipolo fino e dipolo cruzado sobre camadas de substratos diel?tricos anisotr?picos uniaxiais para orienta??es de eixo ?ptico nas dire??es x, y e z. A an?lise destas estruturas ? realizada atrav?s do m?todo dos potenciais vetoriais de Hertz em combina??o com a t?cnica num?rica de Galerkin , no dom?nio da transforma de Fourier, utilizando-se fun??es de base de dom?nio inteiro. Este estudo consiste no emprego de mais uma t?cnica para an?lise de FSS sobre substratos diel?trico anisotr?picos. E apresenta com o principal constribui??o a introdu??o de mais um par?metro de projeto para determina??o das caracter?sticas de transmiss?o e reflex?o das estruturas peri?dicas, a partir da utiliza??o de diel?tricos anisotr?picos com orienta??es de eixo ?ptico nas dire??es x, y e z do sistema de coordenadas cartesianas. Com o objetivo de validar a t?cnica utilizada, s?o realizadas compara??es entre os resultados num?ricos obtidos neste trabalho e os resultados apresentados por outros autores, para o caso de estruturas de FSS com substratos diel?tricos anisotr?picos e isotr?picos. Tamb?m s?o feitas confronta??es entre resultados experimentais e os num?ricos correspondentes para o caso de FSS com material isotr?picos. O m?todo de an?lise proposto mostrou-se bastante eficiente e preciso. Em um segundo momento, s?o apresentadas as curvas das caracter?sticas de transmiss?o e reflex?o de FSS usando patches condutores sobre uma camada diel?trica anisotr?pica uniaxial com eixo ?pitco orientado nas dire??es x, y e z. A partir da an?lise destas curvas, o desempenho das estgruturas de FSS consideradas em fun??o da orienta??o do eixo ?ptico ? descrito

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