Made available in DSpace on 2014-12-17T14:55:58Z (GMT). No. of bitstreams: 1 TiagoCA_DISSERT.pdf: 3801367 bytes, checksum: 9225a3c3c8dc4d02582f66bec6b853a7 (MD5) Previous issue date: 2012-05-07 / This work shows a theoretical analysis together with numerical and experimental results of transmission characteristics from the microstrip bandpass filters with different geometries. These filters are built over isotropic dielectric substrates. The numerical analysis is made by specifical commercial softwares, like Ansoft Designer and Agilent Advanced Design System (ADS). In addition to these tools, a Matlab Script was built to analyze the filters through the Finite-Difference Time-Domain (FDTD) method. The filters project focused the development of the first stage of filtering in the ITASAT s Transponder receptor, and its integration with the others systems. Some microstrip filters architectures have been studied, aiming the viability of implementation and suitable practical application for the purposes of the ITASAT Project due to its lowspace occupation in the lower UHF frequencies. The ITASAT project is a Universityexperimental project which will build a satellite to integrate the Brazilian Data Collect System s satellite constellation, with efforts of many Brazilian institutes, like for example AEB (Brazilian Spatial Agency), ITA (Technological Institute of Aeronautics), INPE/CRN (National Institute of Spatial Researches/Northeastern Regional Center) and UFRN (Federal University of Rio Grande do Norte). Comparisons were made between numerical and experimental results of all filters, where good agreements could be noticed, reaching the most of the objectives. Also, post-work improvements were suggested. / Esse trabalho apresenta uma an?lise te?rica e resultados num?ricos e experimentais das caracter?sticas de transmiss?o de filtros passa-faixa de microfita, que usam diferentes geometrias. Os filtros s?o constru?dos sobre substratos diel?tricos isotr?picos. A an?lise ? efetuada utilizando-se diferentes programas computacionais comerciais como o Ansoft Designer e o Advanced Design System (ADS). Al?m dessas ferramentas, foram desenvolvidas rotinas computacionais que analisam os filtros atrav?s do m?todo das diferen?as finitas no dom?nio do tempo (FDTD). O projeto dos filtros teve foco no desenvolvimento do primeiro est?gio de filtragem do sistema de recep??o do Transponder do Sat?lite ITASAT e sua integra??o com os demais sistemas. Foram estudadas algumas arquiteturas de filtro passa-faixa de microfita para viabilizar sua aplica??o no Transponder, por sua economia de espa?o na frequ?ncia de opera??o (faixa UHF inferior). O ITASAT ? um projeto que visa a constru??o de um sat?lite de car?ter experimental universit?rio para integrar a constela??o de sat?lites do Sistema Brasileiro de Coleta de Dados, reunindo esfor?os de diversas institui??es do Brasil, incluindo a AEB, o ITA, o INPE/CRN e a UFRN. Foram efetuadas compara??es entre os resultados num?ricos e experimentais para todos os filtros, onde observou-se uma boa concord?ncia, atingindo boa parte dos objetivos. Sugest?es de continuidade do trabalho s?o apresentadas.