Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 161-164).

Errata inserted inside back end-paper. / Bibliography: p. 243-249. / xvi, 249 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis presents a brief overview of microstrip antenna analysis and describes the connections between spectral and spatial domain periodic Green's functions in integral equation methods. A hybrid formulation is applied to a variety of problems from simple metal strip dipoles to more complicated microstrip geometries. A further development to finite array analysis is described. An improvement in the accuracy of this approximative technique is explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1997

Errata inserted inside back end-paper. / Bibliography: p. 243-249. / xvi, 249 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis presents a brief overview of microstrip antenna analysis and describes the connections between spectral and spatial domain periodic Green's functions in integral equation methods. A hybrid formulation is applied to a variety of problems from simple metal strip dipoles to more complicated microstrip geometries. A further development to finite array analysis is described. An improvement in the accuracy of this approximative technique is explored. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1997

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-07-06T20:43:45Z No. of bitstreams: 1 SamantaMH_DISSERT.pdf: 5589913 bytes, checksum: 13f8ab4185b2d9b1c9576d1b7fd6d94b (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:04:50Z (GMT) No. of bitstreams: 1 SamantaMH_DISSERT.pdf: 5589913 bytes, checksum: 13f8ab4185b2d9b1c9576d1b7fd6d94b (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:05:35Z (GMT) No. of bitstreams: 1 SamantaMH_DISSERT.pdf: 5589913 bytes, checksum: 13f8ab4185b2d9b1c9576d1b7fd6d94b (MD5) / Made available in DSpace on 2017-07-18T15:05:42Z (GMT). No. of bitstreams: 1 SamantaMH_DISSERT.pdf: 5589913 bytes, checksum: 13f8ab4185b2d9b1c9576d1b7fd6d94b (MD5) Previous issue date: 2016-12-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The growing development of telecommunications, especially mobile devices, has intensified related searches the microstrip antennas in recent years since they have unique properties and wide range of applications. The constant demand for lighter and more flexible devices boosted research in wearable technology area where electronics are fully embedded in their fibers. In this context, knitted fabrics have the necessary elasticity to create adaptable and sports parts, enabling high mobility and comfort to its users. The textile antennas are malleable and, therefore, have great utility in applications where rigidity of traditional antennas is considered limiting, as in military use clothing and in the biomedical field. This work aims to study and develop microstrip antennas using knitted fabric based composite fibers, showing the procedures and materials used from the characterization and choice of fabrics to the design, manufacture and testing of the textile antenna. The electrical characterization was carried out using a Vector Network Analyzer (ARV) to obtain the electrical properties (permittivity and tangent losses). Obtaining textile properties (weight, dimensional stability, degree and tensile strength) was made in accordance with the technical standards, using the equipment available at the Department of Textile Engineering at the Federal University of Rio Grande do Norte (UFRN). The antenna has been designed using the transmission line model of Fortran program developed in accordance with the electrical properties of textile substrates. Subsequently the antenna was designed and simulated in HFSS® (High Frequency Structural Simulator), where radiation patterns are obtained, return loss, the Smith chart, current density and gain. The best simulated result was implemented with tissue disposed knitted in a three-layer structure according to the dimensions designed, and then the antenna is tested using a spectrum analyzer, which were collected data that allowed the manufacture of the letter Smith and graph of return loss. The experimental data were compared with the simulated and the results analyzed according to the literature that support this paper / O crescente desenvolvimento das telecomunicações, principalmente a de dispositivos móveis, têm intensificado as pesquisas relacionadas as antenas de microfita nos últimos anos, visto que estas possuem propriedades singulares, bem como vasta gama de aplicações. A constante procura por dispositivos mais leves e flexíveis impulsionou as pesquisas na área de tecnologia vestível, onde componentes eletrônicos são inteiramente embutidos em suas fibras têxteis. Nesse contexto, os tecidos malha possuem a elasticidade necessária para criar peças adaptáveis e esportivas, permitindo alta mobilidade e conforto aos seus usuários. As antenas têxteis são maleáveis e, por essa razão, têm grande utilidade em aplicações onde a rigidez das antenas tradicionais é considerada uma limitação, como em roupas de uso militar e na área biomédica. Este trabalho tem como objetivo estudar e desenvolver antenas de microfita utilizando tecido de malha à base de fibras têxteis compostas, mostrando os procedimentos e materiais utilizados desde a caracterização e escolha dos tecidos até o projeto, confecção e testes da antena têxtil. A caracterização elétrica foi realizada através de um Analisador de Redes Vetorial (ARV) para obtenção das propriedades elétricas (permissividade e tangente de perdas). A obtenção das propriedades têxteis (gramatura, estabilidade dimensional, titulação e resistência a tração) foi feita de acordo com as normas técnicas, utilizando os equipamentos disponíveis no Departamento de Engenharia Têxtil da Universidade Federal do Rio Grande do Norte (UFRN). A antena foi dimensionada através do modelo da linha de transmissão em programa desenvolvido na linguagem Fortran de acordo com as propriedades elétricas dos substratos têxteis. Posteriormente a antena foi desenhada e simulada no HFSS® (High Frequency Structural Simulator), onde serão obtidos os diagramas de radiação, perda de retorno, densidade de corrente e ganho. O melhor resultado simulado foi implementado com o tecido de malha disposto numa estrutura de três camadas de acordo com as dimensões projetadas e, em seguida, a antena foi testada através de um analisador de espectro, onde foram coletados dados que permitiram a confecção da carta de Smith e gráfico da perda de retorno. Os dados experimentais foram comparados com os simulados e, os resultados analisados de acordo com a literatura especializada que embasam este trabalho / 2017-07-06

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-07-04T19:21:04Z No. of bitstreams: 1 JoséAPM_DISSERT.pdf: 11175477 bytes, checksum: 06a97520ecfb91560a5b33b0a7a17ca7 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:03:31Z (GMT) No. of bitstreams: 1 JoséAPM_DISSERT.pdf: 11175477 bytes, checksum: 06a97520ecfb91560a5b33b0a7a17ca7 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:06:43Z (GMT) No. of bitstreams: 1 JoséAPM_DISSERT.pdf: 11175477 bytes, checksum: 06a97520ecfb91560a5b33b0a7a17ca7 (MD5) / Made available in DSpace on 2017-07-18T15:07:07Z (GMT). No. of bitstreams: 1 JoséAPM_DISSERT.pdf: 11175477 bytes, checksum: 06a97520ecfb91560a5b33b0a7a17ca7 (MD5) Previous issue date: 2016-12-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The complexity of communication systems drives researches into new types of cheaper and more efficient antennas. Microstrip antennas are planar structures that can be used in various types of applications due to their peculiar characteristics. There are several techniques in the literature to improve the performance of these antennas, among them the use of metasurfaces. The working principle of these structures is similar to a metamaterial, based on constitutive properties, permissiveness and permeability, which are not found in materials in nature, resulting in a negative refractive index. The present work has the objective of analyzing the application of metasurfaces in planar antennas in the range of microwaves, in the frequencies of 1 to 10 GHz that comprise the bands L, S, C and part of band X, through the application of rectangular and circular SRR structures in the patch and ground plane of the antennas. The structures were divided into sizes λ/10, λ/15 and λ/20. The antennas were first analyzed by means of simulation with the commercial software HFSS®, with the simulated results were selected four antennas for manufacturing, of which the measured results of the parameters were obtained in a vector network analyzer, namely: loss of return, Gain and impedance matching. The results of the antennas manufactured were in agreement with the simulations / A complexidade dos sistemas de comunicação impulsionam as pesquisas por novos tipos de antenas mais baratas e eficientes. Antenas de microfita são estruturas planares que podem ser utilizadas em vários tipos de aplicações devido as suas características peculiares. Existem na literatura várias técnicas para melhorar o rendimento dessas antenas, dentre elas se destaca o uso das Metassuperfícies. O princípio de funcionamento dessas estruturas é similar ao de um metamaterial, baseiam-se nas propriedades constitutivas, permissividade e permeabilidade, que não são encontrados em materiais na natureza, resultando em um índice de refração negativo. O presente trabalho tem por objetivo analisar a aplicação de estruturas Metassuperfície em antenas planares na faixa de micro-ondas, nas frequências de 1 a 10 GHz que compreendem as bandas L, S, C e parte da banda X, mediante a aplicação das estruturas SRR do tipo retangular e circular no patch e no plano de terra das antenas, as estruturas foram divididas nos tamanhos λ/10, λ/15 e λ/20. As antenas foram primeiramente analisadas por meio de simulação com o software comercial HFSS®, com os resultados simulados foram selecionadas quatro antenas para fabricação, das quais os resultados medidos dos parâmetros foram obtidos em um analisador de redes vetoriais, a saber: perda de retorno, ganho e casamento de impedância. Os resultados das antenas fabricadas apresentaram concordância com as simulações / 2017-07-04

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2018-06-11T17:51:51Z No. of bitstreams: 1 AlexandreMA_DISSERT.pdf: 21200920 bytes, checksum: 988dc3f3c5290a8f67225c05b46914a0 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T16:52:15Z (GMT) No. of bitstreams: 1 AlexandreMA_DISSERT.pdf: 21200920 bytes, checksum: 988dc3f3c5290a8f67225c05b46914a0 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T16:53:10Z (GMT) No. of bitstreams: 1 AlexandreMA_DISSERT.pdf: 21200920 bytes, checksum: 988dc3f3c5290a8f67225c05b46914a0 (MD5) / Made available in DSpace on 2018-06-18T16:53:22Z (GMT). No. of bitstreams: 1 AlexandreMA_DISSERT.pdf: 21200920 bytes, checksum: 988dc3f3c5290a8f67225c05b46914a0 (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Demand in wireless networks has increased considerably in recent years. Consequently, the study of system components has also increased. Within this context, antennas are fundamental elements in the physical layer in radiofrequency communications, and their study has become a research area with great advances. The need in certain systems for smaller antennas and more adaptability in the space makes the microstrip antennas in potential substitutes of the traditional antennas. This work aims to find prototypes of microfite antennas that have physical and electrical characteristics, such as gain and polarization, superior to the commercial antennas of a FPV communication system (First Person View) operating at 5.8 GHz. The methodology used in this research consists of a theoretical survey about circular polarization antennas, design, simulate and construct these antennas using different substrates in order to verify their performance and to ship them in an FPV system. The results obtained through the simulation are compared with the experimental results in order to attest to the model in question based on the literature used in this work. Preliminarily, the simulated and measured results show that the Triangular Patch Antennas have all the desirable characteristics for operation in the FPV system, being possible to board them for the obtaining of images and analysis of the performance of the system / A demanda em redes de comunicação sem fio tem aumentado consideravelmente nos últimos anos. Consequentemente, o estudo dos componentes dos sistemas também aumentou. Dentro desse contexto, as antenas são elementos fundamentais na camada física em comunicações via radiofrequência, e o seu estudo tornou-se uma área de pesquisa com grandes avanços. A necessidade em determinados sistemas por antenas de menor porte e mais adaptabilidade no espaço tornam as antenas de microfita em potenciais substitutos das antenas tradicionais. Diante disso, esse trabalho objetiva encontrar protótipos de antenas de microfita que possuam características físicas e elétricas, como ganho e polarização, superiores às antenas comerciais de um sistema de comunicação em FPV (First Person View), operando em 5.8 GHz. A metodologia utilizada nessa pesquisa consiste em um levantamento teórico acerca das antenas de polarização circular, projetar, simular e construir estas antenas utilizando diferentes substratos a fim de verificar seu desempenho e embarcá-las em um sistema FPV. Os resultados obtidos através da simulação são comparados com os resultados experimentais a fim de atestar o modelo em questão com base na literatura empregada neste trabalho. Preliminarmente, os resultados simulados e medidos mostram que as Antenas Patch Triangular possuem todas as características desejáveis para operação no sistema FPV, sendo possível embarcá-las para a obtenção de imagens e análise de desempenho do sistema com as mesmas / 2018-06-11

Submitted by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-05-02T18:24:47Z No. of bitstreams: 1 KaíckVOC_DISSERT.pdf: 2201549 bytes, checksum: 0aa156688ef6e55d0663212f326229e2 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T16:54:06Z (GMT) No. of bitstreams: 1 KaíckVOC_DISSERT.pdf: 2201549 bytes, checksum: 0aa156688ef6e55d0663212f326229e2 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2018-06-18T16:54:44Z (GMT) No. of bitstreams: 1 KaíckVOC_DISSERT.pdf: 2201549 bytes, checksum: 0aa156688ef6e55d0663212f326229e2 (MD5) / Made available in DSpace on 2018-06-18T16:55:00Z (GMT). No. of bitstreams: 1 KaíckVOC_DISSERT.pdf: 2201549 bytes, checksum: 0aa156688ef6e55d0663212f326229e2 (MD5) Previous issue date: 2018-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Microstrip antennas have a potential that was only initially studied in 1953, to receive more attention only in the 1970s. Since then, several techniques, methods of analysis, algorithms, and materials have been developed to study, understand and produce these antennas. Advantages such as low cost, small dimensions, low weight and volume, aerodynamically advantageous format, possibility to have flat or curved format made this antenna one of the most interesting for the military area, and now for commercial and industrial area. This work has as objective at the development of substrates for microfite antennas using Ni-Zn-type Ferrites using the Sol-Gel technique, a physicochemical process that allows the obtaining of nanometric particles, in view of the ease of execution of this technique. The experiments consisted in the production of three types of ferrites, NiFe2O4, ZnFe2O4 and Ni0,5Zn0,5Fe2O4 in which these pellets were used as substrates of the microfite antennas. Then, simulations were carried out using commercial HFSS software to verify the influence of the magnetic properties of the material on antenna parameters such as return loss, bandwidth, and Smith's chart. The simulated results were divided into groups called dielectric and standard, in which these groups differed in the presence or absence of the magnetic characteristics of the material. All the results were compared with the values measured and analyzed by verifying some effects such as the reduction of the resonance frequency of the antennas / As antenas de microfita têm um potencial que só foi inicialmente estudado em 1953, para receber mais atenção somente na década de 1970. Desde então foram desenvolvidas diversas técnicas, métodos de análises, algoritmos, e materiais com o intuito de estudar, compreender e produzir estas antenas. Vantagens como custo baixo, pequenas dimensões, baixo peso e volume, formato aerodinamicamente vantajoso, possibilidade de ter formato plano ou curvo fizeram desta antena uma das mais interessantes para a área militar, e agora para a área comercial e industrial. Este trabalho visou o desenvolvimento de substratos para as antenas de microfita utilizando Ferritas do tipo Ni-Zn através da técnica de Sol-Gel, um processo físico-químico que permite a obtenção de partículas nanométricas, tendo em vista a facilidade de execução dessa técnica. Os experimentos consistiram na produção de três tipos de pastilhas de Ferritas, NiFe2O4, ZnFe2O4 e Ni0,5Zn0,5Fe2O4 em que essas pastilhas foram utilizadas como substratos das antenas de microfita. Em seguida, foi realizado simulações, por meio do software comercial HFSS®, com o objetivo de verificar a influência das propriedades magnéticas do material em parâmetros das antenas como perda de retorno, largura de banda, carta de Smith. Os resultados simulados foram divididos em grupos chamados de dielétrico e padrão, no qual esses grupos se diferenciavam no tocante a presença ou não das características magnéticas do material. Todos os resultados foram comparados com os valores medidos e analisados verificando alguns efeitos como a redução da frequência de ressonância das antenas / 2018-05-02

A novel microstrip patch antenna topology is presented for achieving a dual-band response with arbitrarily closely spaced resonances. This topology is based on a coupled transmission line structure in order to take advantage of the separation in propagation constants for parallel (even-mode) and anti-parallel (odd-mode) current modes. Applying a metamaterials inspired design approach, periodic reactive load­ings are used to design the underlying transmission line to have specific propagation constants necessary to realize a desired separation between two resonant frequencies. Using a single probe feed for a finite coupled line segment, both even-and odd-mode resonances can be excited to radiate efficiently at their respective design frequencies. The efficiency of the odd-mode radiation is enhanced by separating the two lines, while strong coupling is maintained by inserting a series of narrowly-separated thin loops between them. Several example resonant antenna designs, in the 2.45 GHz band, are presented. The directivities of these microstrip patch antennas are enhanced by optimizing the physical length of the resonant structure. For a resonant antenna obtained by cas­cading several unit cells of reactively loaded microstrip segments, dispersion analysis is employed for the unit-cell design. Maximum directivity is achieved by choosing the overall physical length to be slightly less than a half wavelength in free space at the design frequency. This gain optimization is applied to three coupled-line antennas, as well as a single resonance patch. Excellent agreement is observed between simulated and measured responses across all designs. The potential of loading the coupled line structure with active components is also explored. Varactor diodes are placed on coupled-line structures in two configurations. In one configuration, both resonant frequencies are affected. In the other configura­tion, only the odd-mode characteristics are reconfigured. In this way, the resonant frequency of either one or both modes can be adjusted by applying a DC bias voltage to the varactor diode loading elements. Two antennas, one employing each of these topologies, were designed and fabricated. Control of the resonant frequency over the predicted range through applying a bias voltage is observed with the fabricated prototypes.

No description available.

The Finite-Difference Time-Domain (FDTD) method has gained tremendous popularity in the past decade as a tool for solving Maxwell's equations. Phased Array Antennas find several applications including mobile communications ( cellular, personal communication systems and networks), satellite communications, global positioning system (GPS), aeronautical and radar systems. This dissertation describes the application of the FDTD method for calculating broadband characteristics of finite-sized phased array antennas consisting of microstrip elements fed with coaxial probes. The characterization of such antennas is dependent upon the development of simulation tools that can accurately model general topologies including wires, dielectrics, conductors lumped elements and metallic strips. The use of these simulation tools reduces the cost and effort associated with fabricating and testing phased array antennas. The FDTD formulation is inherently broadband, very general, and easily accorrunodates arbitrary conductor geometry and dielectric configurations. The FDTD method is implemented and applied to determine the input impedance, radiation-patterns and gain of microstrip antennas. Next, the main contributions of this work are described which include the full time-domain characterization of broadband characteristics of finite-sized phased array antennas for different scan conditions. Active reflection coeffici nt gain scan-element patterns and scanning-array radiation patterns are calculated.