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Previous issue date: 2015-12-10 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esse trabalho apresenta uma t?cnica h?brida de projeto de superf?cies seletivas em frequ?ncia, sobre uma camada diel?trica isotr?pica, considerando diversas geometrias para os elementos das c?lulas unit?rias. Especificamente, a t?cnica h?brida usa o m?todo do circuito equivalente em conjunto com algoritmos gen?ticos, visando a s?ntese de estruturas com resposta singleband e dual-band. O m?todo do circuito equivalente permite modelar a estrutura por meio de um circuito equivalente e tamb?m a obten??o de circuitos para diferentes geometrias. A partir da obten??o dos par?metros desses circuitos, podem-se obter as caracter?sticas de transmiss?o e de reflex?o das estruturas modeladas. Para obter a otimiza??o das estruturas modeladas, de acordo com a resposta em frequ?ncia desejada, a ferramenta de otimiza??o do Matlab optimtool mostrou-se de f?cil utiliza??o, permitindo explorar resultados importantes na an?lise de otimiza??o. No trabalho, s?o apresentados resultados num?ricos e experimentais para as caracter?sticas de transmiss?o de diferentes geometrias analisadas. Foram efetuadas compara??es com resultados apresentados na literatura, tendo-se observado uma boaconcord?ncia nos casos analisados para estruturas com substratos isotr?picos. / This thesis presents a hybrid technique of frequency selective surfaces project
(FSS) on a isotropic dielectric layer, considering various geometries for the elements of
the unit cell. Specifically, the hybrid technique uses the equivalent circuit method in
conjunction with genetic algorithm, aiming at the synthesis of structures with response
single-band and dual-band. The equivalent circuit method allows you to model the
structure by using an equivalent circuit and also obtaining circuits for different
geometries. From the obtaining of the parameters of these circuits, you can get the
transmission and reflection characteristics of patterned structures. For the optimization
of patterned structures, according to the desired frequency response, Matlab?
optimization tool named optimtool proved to be easy to use, allowing you to explore
important results on the optimization analysis. In this thesis, numeric and experimental
results are presented for the different characteristics of the analyzed geometries. For
this, it was determined a technique to obtain the parameter N, which is based on genetic
algorithms and differential geometry, to obtain the algebraic rational models that
determine values of N more accurate, facilitating new projects of FSS with these
geometries. The optimal results of N are grouped according to the occupancy factor of
the cell and the thickness of the dielectric, for modeling of the structures by means of
rational algebraic equations. Furthermore, for the proposed hybrid model was developed
a fitness function for the purpose of calculating the error occurred in the definitions of
FSS bandwidths with transmission features single band and dual band. This thesis deals
with the construction of prototypes of FSS with frequency settings and band widths
obtained with the use of this function. The FSS were initially reviewed through
simulations performed with the commercial software Ansoft Designer ?, followed by
simulation with the equivalent circuit method for obtaining a value of N in order to
converge the resonance frequency and the bandwidth of the FSS analyzed, then the
results obtained were compared. The methodology applied is validated with the
construction and measurement of prototypes with different geometries of the cells of the
arrays of FSS.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21140 |
| Date | 10 December 2015 |
| Creators | Ara?jo, Gilmara Linhares de |
| Contributors | 79090095420, http://lattes.cnpq.br/1982228057731254, Gomes Neto, Alfredo, 33312079420, http://lattes.cnpq.br/1403715441701958, Martins, Allan de Medeiros, 01979076448, http://lattes.cnpq.br/4402694969508077, Fernandes, Humberto Cesar Chaves, 13097628487, http://lattes.cnpq.br/0246709532151067, Andrade, Humberto Dionisio de, 91620040425, http://lattes.cnpq.br/1253785596446469, Silva, Jos? Patrocinio da, 67160042468, http://lattes.cnpq.br/5753289728835624, Campos, Antonio Luiz Pereira de Siqueira |
| 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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