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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

Estudo da convers?o de polariza??o linear-circular em antenas dual-band para leitores RFID port?teis usando metasuperf?cies miniaturizadas

Montalv?o, Augusto C?sar Pereira da Silva 04 July 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-12-29T16:36:10Z No. of bitstreams: 1 AugustoCesarPereiraDaSilvaMontalvao_TESE.pdf: 3356285 bytes, checksum: 91694fd2667b473c4c31ff9be48f2171 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-02T18:07:35Z (GMT) No. of bitstreams: 1 AugustoCesarPereiraDaSilvaMontalvao_TESE.pdf: 3356285 bytes, checksum: 91694fd2667b473c4c31ff9be48f2171 (MD5) / Made available in DSpace on 2017-01-02T18:07:35Z (GMT). No. of bitstreams: 1 AugustoCesarPereiraDaSilvaMontalvao_TESE.pdf: 3356285 bytes, checksum: 91694fd2667b473c4c31ff9be48f2171 (MD5) Previous issue date: 2016-07-04 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Este trabalho tem como objetivo propor uma nova estrutura capaz de converter sinais linearmente polarizados gerados por uma antena de microfita em sinais circularmente polarizados, para duas bandas de opera??o (2,45 GHz e 5,8 GHz), para aplica??o em leitores RFID port?teis, usando duas metasuperf?cies miniaturizadas. Para poder estudar o comportamento da estrutura proposta, s?o utilizados tr?s layouts diferentes. Primeiro s?o feitos testes iniciais de simula??o, utilizando a primeira metasuperf?cie acoplada ? antena. Em seguida, a antena ? testada acoplada ? segunda metasuperf?cie. E posteriormente a antena ? acoplada ?s duas metasuperf?cies. As estruturas s?o analisadas numericamente atrav?s do Ansoft HFSS? e para validar esses resultados, as estruturas s?o caracterizadas experimentalmente. S?o apresentadas as caracter?sticas de transmiss?o simuladas e medidas. Os resultados experimentais mostram uma boa concord?ncia com os resultados simulados. A estrutura aqui proposta apresenta a vantagem de atender ?s caracter?sticas desejadas nas duas bandas de interesse, conseguindo obter excelentes valores de largura de banda de perda de retorno, bem como de raz?o axial, sendo uma estrutura simples de ser constru?da e com baixo custo. / This work aims to propose a new structure able to convert signals linearly polarized generated by a microstrip antenna for circularly polarized signals at two operating bands (2.45 GHz and 5.8 GHz), for use in portable RFID readers, using two miniaturized metasurfaces. In order to study the behavior of the proposed structure, three different layouts are used. First initial simulation tests are made, using the first metasurface coupled to the antenna. Then, the antenna is tested coupled to the second metasurface. Posteriorly the antenna is coupled to the two metasurfaces. The structures are analyzed numerically through ANSYS HFSS?, and to validate these results, the structures are characterized experimentally. The characteristics of transmissions simulated and measures are presented. A good agreement between simulated and measured results was obtained. The structure proposed here has the advantage to meet desired characteristics in two bands of interest, obtaining excellent values of return loss wideband, as well as the axial ratio, being a simple structure to be constructed and with low cost.

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