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Previous issue date: 2015-01-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Este trabalho tem como objetivo investigar o comportamento de elementos fractais e elementos helicoidais em estruturas planares de microfita. Em particular, as superf?cies seletivas de frequ?ncia (FSS) tiveram seus elementos convencionais alterados para formatos fractais e para o formato helicoidal. O substrato diel?trico usado ? de fibra de vidro (FR-4) e tem espessura de 1,5 mm, permissividade el?trica relativa de 4,4 e tangente de perdas igual a 0,02. Para as FSS, adotou-se a geometria fractal pentagonal de D?rer e a geometria helicoidal. Para efetuar as medi??es, foram utilizadas duas antenas cornetas em visada direta, conectadas por cabo coaxial a um analisador de redes vetorial. Alguns prot?tipos foram selecionados para fabrica??o e medi??o. A partir dos resultados preliminares obtidos, objetivou-se encontrar aplica??es pr?ticas para as estruturas a partir do cascateamento entre elas. Para as FSSs com elementos fractais de D?rer, observou-se um comportamento multibanda proporcionado pela geometria fractal, ao mesmo tempo em que a largura de banda se tornou estreita na medida em que o n?vel de itera??o fractal aumentou, tornando-a uma estrutura mais seletiva em frequ?ncia, com um maior fator de qualidade. Uma an?lise param?trica possibilitou a an?lise da influ?ncia da varia??o da camada de ar entre elas. As estruturas fractais pentagonais foram consideradas e cascateadas. O cascateamento entre determinadas estruturas pentagonais apresentou um comportamento tri-band para determinados valores da camada de ar entre elas, com aplica??es na banda licenciada 2,5 GHz (2,3 ~ 2,7 GHz), e 3,5 GHz (3,3 ~ 3,8 GHz). Para as FSSs com elementos helicoidais, seis estruturas foram consideradas. A partir de resultados preliminares obtidos com a an?lise isolada das estruturas, o cascateamento entre elas proporcionou o aumento da largura de banda, na medida em que a espessura da camada de ar aumenta. Com a finalidade de encontrar aplica??es pr?ticas para as estruturas helicoidais cascateadas, as estruturas propostas foram cascateadas e as mesmas encontraram aplica??es na banda-X (8,0 ~ 12,0 GHz), e na banda n?o licenciada que compreende a faixa de 5,25 a 5,85 GHz. Na caracteriza??o num?rica e experimental das estruturas abordadas, utilizou-se, respectivamente, o software comercial Ansoft Designere um analisador de redes vetorial, modelo N5230A da Agilent. / This work aims to investigate the behavior of fractal and helical elements structures in planar microstrip. In particular, the frequency selective surfaces (FSSs) had changed its conventional elements to fractal and helical formats. The dielectric substrate used was fiberglass (FR-4) and has a thickness of 1.5 mm, a relative permittivity 4.4 and tangent loss equal to 0.02. For FSSs, was adopting the D?rer?s fractal geometry and helical geometry. To make the measurements, we used two antennas horns in direct line of sight, connected by coaxial cable to the vector network analyzer. Some prototypes were select for built and measured. From preliminary results, it was aimed to find practical applications for structures from the cascading between them. For FSSs with D?rer?s fractal elements was observed behavior provided by the multiband fractal geometry, while the bandwidth has become narrow as the level of iteration fractal increased, making it a more selective frequency with a higher quality factor. A parametric analysis allowed the analysis of the variation of the air layer between them. The cascading between fractal elements structure were considered, presented a tri-band behavior for certain values of the layer of air between them, and find applications in the licensed 2.5GHz band (2.3-2.7) and 3.5GHz band (3.3-3.8). For FSSs with helical elements, six structures were considered, namely H0, H1, H2, H3, H4 and H5. The electromagnetic behavior of them was analyzed separately and cascaded. From preliminary results obtained from the separate analysis of structures, including the cascade, the higher the bandwidth, in that the thickness of the air layer increases. In order to find practical applications for helical structures cascaded, the helical elements structure has been cascaded find applications in the X-band (8.0-12.0) and unlicensed band (5.25-5.85). For numerical and experimental characterization of the structures discussed was used, respectively, the commercial software Ansoft Designer and a vector network analyzer, Agilent N5230A model.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/20260 |
| Date | 30 January 2015 |
| Creators | Trindade, Jos? Idifranse Aguiar |
| Contributors | 04401565487, D'Assun??o J?nior, Adaildo Gomes, 00980645417, http://lattes.cnpq.br/7359899329008024, Lins, Hertz Wilton de Castro, 75112302453, http://lattes.cnpq.br/7712686175574736, Silva, Jefferson Costa e, 60137495404, http://lattes.cnpq.br/7399512856151138, Oliveira, Jos? de Ribamar Silva, 12559520320, http://lattes.cnpq.br/4002176927695547, Mendon?a, La?rcio Martins de, 09064087415, http://lattes.cnpq.br/1853488415531363, D'Assun??o, Adaildo Gomes |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA EL?TRICA E DE COMPUTA??O, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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