Nowadays, demands for fully integrated and miniaturized RFIC (Radio Frequency Integrated Circuits) have increased in wireless microwave communication system. Passive components such as coupler, divider and filters are always fabricated in outside of ICs due to their bulky sizes, which have been a great barrier to a realization of a fully integrated design. To solve this problem, miniaturization of passive components is one of the big issues at the present time. This paper shows the development of two important microwave passive components, quadrature hybrid and rat-race couplers for LTE lower (698 -960 MHz) and higher (1.71 - 2.70 GHz) frequency bands, which are obtained by replacing quarter-wave (λ/4) transmission line of a conventional coupler by their equivalent coupled line, resulting in significant size reduction. The miniaturized quadrature and rat race couplers are designed and fabricated with a Rogers 4360 substrate as a platform in producing significantly reduction. The design is validated by electromagnetic simulation and measurement. The size of the implemented quadrature hybrid coupler is 30 × 26.8 mm^2 and 14.9 × 12.5 mm^2, which are 82.60 % and 69.03% compared to the conventional couplers for lower and higher frequency band respectively. And, 55.5 × 27.9 mm^2 and 19.2 × 14.8 mm^2 for rat race coupler, which are 79.69 % and 62.35 % compared to the conventional coupler for lower and higher frequency band, respectively. Also, the reflection coefficient and the isolation are as good as conventional one and coupling procedure is similar or better than it.

Made available in DSpace on 2014-12-17T14:55:50Z (GMT). No. of bitstreams: 1 AndersonMCS_DISSERT.pdf: 542550 bytes, checksum: cf969edd5c8c6cd5c0f0dcbf4f8113e0 (MD5) Previous issue date: 2011-07-26 / The modern society depends on an efficient communications system able to of transmitting and receiving information with a higher speed and reliability every time. The need for ever more efficient devices raises optimization techniques of microstrip devices, such as techniques to increase bandwidth: thicker substrates and substrate structures with EBG (Electromagnetic Band Gap) and PBG (Photonic Band Gap). This work has how aims the study of the application of PBG materials on substrates of planar structures in microstrip, more precisely in directional quadrature couplers and in rat-race and impedance of transformers. A study of the planar structures in microstrip and substrates EBG is presented. The PBG substrates can be used to optimize the radiation through the air, thus reducing the occurrence of surface waves and the resulting diffraction edge responsible for degradation of radiation pattern. Through specific programs in FORTRAN Power Station obtained the frequencies and couplings for each structure. Are used the program PACMO - Computer Aided Design in Microwave. Results are obtained of the frequency and coupling devices, ranging the frequency band used (cellular communication and Wimax systems) and the permittivity of the substrate, comparing the results of conventional material and PBG materials in the s and p polarizations. / A sociedade moderna depende de um eficiente sistema de comunica??es, capaz de transmitir e receber informa??es com uma velocidade e confiabilidade maiores a cada momento. A necessidade de dispositivos cada vez mais eficientes faz surgir t?cnicas de otimiza??o dos dispositivos em microfita, como por exemplo, t?cnicas para aumentar a largura de banda: substratos mais espessos e estruturas com substratos de Banda Eletromagn?tica Proibida - EBG (Electromagnetic Band Gap) e Banda Fot?nica Proibida - PBG (Photonic Band Gap). Este trabalho tem como objetivo o estudo da aplica??o de materiais EBG/PBG em substratos de estruturas planares em microfita, mais precisamente em acopladores direcionais em quadratura e em anel e em transformadores de imped?ncias. ? apresentado um estudo das estruturas planares em microfita e dos substratos EBG/PBG. Substratos PBG podem ser usados para otimizar a irradia??o pelo ar, reduzindo assim a ocorr?ncia de ondas superficiais e a conseq?ente difra??o de borda respons?vel pela degrada??o do diagrama de radia??o. Atrav?s de programas espec?ficos em FORTRAN obtiveram-se as freq??ncias e acoplamentos para cada estrutura. Foi utilizado o programa PACMO Projeto Auxiliado por Computador para Microondas. S?o obtidos resultados da freq??ncia e acoplamentos dos dispositivos, variando-se banda de freq??ncia utilizada (sistemas de comunica??o celular e Wimax) e a permissividade do substrato, comparando-se os resultados de materiais convencionais e materiais PBG nas polariza??es s e p.