Submitted by Alex Sandro R?go (alex@ifpb.edu.br) on 2016-09-01T13:11:30Z No. of bitstreams: 1 An?lise e Simula??o de Filtros de Microfita Utilizando o M?todo FDTD.pdf: 3682016 bytes, checksum: e7b92fd51edaba9be1f80daf86f10b4d (MD5) / Approved for entry into archive by Alex Sandro R?go (alex@ifpb.edu.br) on 2016-09-01T13:12:05Z (GMT) No. of bitstreams: 1 An?lise e Simula??o de Filtros de Microfita Utilizando o M?todo FDTD.pdf: 3682016 bytes, checksum: e7b92fd51edaba9be1f80daf86f10b4d (MD5) / Made available in DSpace on 2016-09-01T13:12:05Z (GMT). No. of bitstreams: 1 An?lise e Simula??o de Filtros de Microfita Utilizando o M?todo FDTD.pdf: 3682016 bytes, checksum: e7b92fd51edaba9be1f80daf86f10b4d (MD5) Previous issue date: 2015 / Esta Disserta??o descreve a aplica??o do m?todo das Diferen?as Finitas no Dom?nio do Tempo (FDTD ? Finite Difference Time Domain) para a an?lise de filtros fabricados em linhas de microfita para a faixa de micro-ondas. O m?todo FDTD 3-D, desenvolvido em linguagem C, implementa condi??es de contorno com o uso da t?cnica PML (Perfect Matched Layer), permitindo a determina??o num?rica dos campos eletromagn?ticos com uma menor interfer?ncia das reflex?es indesej?veis nos limites da malha FDTD. A fim de comparar os resultados obtidos com o m?todo FDTD, o software comercial Ansoft DesignerTM tamb?m ? usado para simula??o dos filtros abordados. Cinco prot?tipos foram constru?dos e caracterizados experimentalmente com o uso de um analisador de redes vetorial, Agilent N5230A. Estes resultados num?ricos e experimentais s?o usados para a compara??o do m?todo FDTD 3-D desenvolvido. O m?todo FDTD foi aplicado para an?lise de um filtro passa-baixa em linha de microfita, de filtros DGS (Defected Ground Structure) unit?rios e peri?dicos e de um filtro spur-line. Os resultados de simula??o foram concordantes com os experimentos realizados com um erro m?ximo de 4,8% para os filtros abordados. Atrav?s de varia??es na malha FDTD, uma an?lise de desempenho do m?todo FDTD foi realizada em termos de precis?o e esfor?o computacional.

This thesis reports the analysis of the rectangular shaped defected ground structure (RS-DGS) and the application of the structure on some microwave devices. DGS is analyzed in terms of its superior properties, which enables the designers to easily realize many kind of microwave devices which are impossible to achieve with the standard applications. Within the scope of this thesis, the focus is on the rectangular shaped DGS and its characteristic properties. The basic slow wave and high impedance characteristics are utilized in the design of some microwave devices. The design is carried on at the two different frequency bands: X-band and Ka band, centering at 10 GHz and 35 GHz, respectively. Finally, using the high impedance property and the coupling between the defects, a wide band 1 : 4 beam forming network is designed and implemented at 10 GHz.

The thesis deals with the microstrip filter design using defected ground structure (DGS). The difference between standard asymmetric microstrip technique and DGS is in using the structures etched in the microwave substrate ground plane. The DGS resonant characteristics are then used in filter design. The thesis consists of three factual parts. The first one (chapter 4) introduces the use of the DGS resonators in the lowpass filter design. It involves experimental analysis of one type of the lowpass filter. The second part (chapter 5) deals with a novel microstrip lowpass filter design method using DGS. The proposed method is verified by simulations and several samples are realized and measured. Finally, the third part (chapters 7 and 8) deals with the bandpass filter design using specific defected ground structure as a resonator. The resonators are used in a coupled resonator structure. Filters of various orders and resonator configurations are designed and simulated. A combination of the DGS resonators and half-wavelength microstrip resonators is introduced as well. Selected samples are realized and measurement results are compared with simulations.