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Previous issue date: 2016-06-06 / A efici?ncia no uso das radiofrequ?ncias (RF) ? um fator determinante na
capacidade de qualquer sistema de comunica??es m?veis. O aprimoramento da
utiliza??o desses recursos tornou-se interessante desde os prim?rdios desses sistemas.
As tecnologias e servi?os digitais tem demandado maior aloca??o RF para suprir
requisitos de largura de banda (BW). O desenvolvimento de tecnologias emergentes
baseadas em aloca??o din?mica de RF tem sido apontado como uma solu??o para essa
crescente necessidade de BW e motiva??o para a realiza??o de recentes pesquisas sobre
os sistemas de r?dios cognitivos (CRS). Neste trabalho, s?o propostas antenas de banda
ultra larga (UWB) para sensoriamento espectral, assim como antenas reconfigur?veis
em frequ?ncia para aplica??es em CRS, os quais realizam de forma din?mica a
transmiss?o e recep??o de sinais em banda estreita (NB). Dentre os prot?tipos
propostos, s?o trazidos modelos capazes de cobrir todo o espectro de 3,1 GHz a 10,6
GHz, assim como, de forma reconfigur?vel, cobrir essa faixa de RF em v?rias NB, com
destaque para a frequ?ncia de 5,8 GHz. Ademais, as antenas propostas passaram por
processos de otimiza??o e s?ntese baseados em ferramentas de intelig?ncia
computacional quais sejam: algoritmo gen?tico (GA), o algoritmo de otimiza??o de
enxames de part?culas (PSO), assim como o algoritmo de otimiza??o de col?nia de
abelhas artificial (ABC). Como resultados, melhorias na BW e no coeficiente de
reflex?o das antenas foram encontradas. As simula??es e parametriza??es
computacionais, assim como as an?lises num?ricas com GA, foram realizadas com
aux?lio do software HFSS. J? as an?lises num?ricas com algoritmos PSO e ABC foram
implementadas em Java. Para fins de valida??o, os resultados dessas simula??es foram
comparados com resultados experimentais, tendo sido observada boa concord?ncia para
os diversos prot?tipos de antenas planares propostos e desenvolvidas neste trabalho. / The effective usage of radio frequencies (RF) is a determining factor in the
capacity of any mobile communications system. Improving the use of these resources
has become very popular since the early days of these systems. The technologies and
digital services have demanded higher RF allocation to meet bandwidth (BW)
requirements. The development of emerging technologies based on dynamic RF
allocation has been considered as a solution to this growing need for BW and
motivation to carry out recent research on cognitive radio systems (CRS). In this work,
UWB antennas are proposed for spectral sensing, as well as frequency reconfigurable
antennas for CRS applications, which dynamically perform transmitting and receiving
signals in narrowband (NB). Among the proposed prototypes, the presented models are
able to cover the entire UWB spectrum from 3.1 GHz to 10.6 GHz. When working as
reconfigurable antennas, the prototypes can cover the RF range in various NB, like
5.8 GHz. Moreover, the proposed antenna passed through optimization and synthesis
processes based on computational intelligence tools. Genetic algorithm (GA), particle
swarm optimization (PSO) algorithm, and artificial bee colony (ABC) algorithm are the
used algorithms. As results, improved BW and the better antenna reflection coefficient
were found. The computational simulations and the numerical analysis based on GA
were performed using the HFSS software. In addition, numerical analyses with PSO and
ABC algorithms were implemented in Java. For validation purposes, simulation results
were compared with experimental results showing good agreement for all the proposed
planar antennas prototypes developed in this work.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/22516 |
| Date | 06 June 2016 |
| Creators | Rodrigues, Eduardo Jorge Brito |
| Contributors | 04401565487, D'Assun??o J?nior, Adaildo Gomes, 00980645417, Dupouy, Emmanuel Beno?t Jean Baptiste, 01733681400, http://lattes.cnpq.br/3718393572235479, Lins, Hertz Wilton de Castro, 75112302453, http://lattes.cnpq.br/7712686175574736, Oliveira, Jose de Ribamar Silva, 12559520320, http://lattes.cnpq.br/4002176927695547, Mendon?a, Laercio Martins de, 09064087415, http://lattes.cnpq.br/1853488415531363, Melo, Marcos Tavares de, http://lattes.cnpq.br/4933635747860906, 23162767415, D'Assun??o, Adaildo Gomes |
| Publisher | 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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