[pt] Neste trabalho é feita uma análise das características de transmissão de estruturas microstrip blindadas e contendo várias camadas de dielétrico. O problema é formulado em termos de uma representação rigorosa de modos híbridos, superposição de modos TE e TM. A equação característica para as propriedades de dispersão dessas linhas é obtida pela aplicação da técnica da matriz de transferência da estrutura em associação com o método de Galerkin no domínio espectral. As principais vantagens do método são sua simplicidade e convergência rápida, permitindo a caracterização dos modos fundamental e de ordem superior. São apresentados resultados teóricos e práticos para linhas isoladas acopladas e ressoadores lineares, comparando-se com outros autores. Os efeitos de metalização, perdas e descontinuidades são também considerados. / [en] A hybrid mode analysis is presented for a multilayer dielectric within a rectangular conducting box. An arbitrary set of planar conductors may be distributed along one of the surfaces. The problem is formulated in terms of a rigorous hybrid-mode representation, superposition of TE and TM fields. The analysis combines a transfer-matrix approach with Galerkin´s method in the spectral domain to give a characteristic equation for the dispersion properties of the lines. Among the advantages of the method are its simplicity and rapid convergence, allowing a characterization of the fundamental and higher order modes. Theoretical and practical results are presented, for single/coupled lines and linear resonators, and they are compared with the results presented by other authors. The effects due to metallization, loss and discontinuities are also considered.

In the first part of the thesis, the 2-D structures in stratified media are analyzed using an efficient MoM technique. The method is used to optimize transmitted or reflected electric fields from the 2-D structures. The genetic algorithm is used in the optimization process. In the second part a 3-D MoM technique is implemented to analyze multilayered structures with periodically implanted material blocks. Using the method, the dispersion and reflection characteristics of the structure are calculated for different configurations. The results are compared with the results found in the literature and it is seen that they are in good agreement. Asymptotic Waveform Evaluation (AWE) technique is utilized to obtain the Pade approximation of the solution in terms of frequency. The high order derivatives that are required by the AWE technique are calculated through Automatic Differentiation technique. Using the AWE method, the dispersion diagram and reflection characteristics of the periodic structures are obtained in a shorter time. The results are compared with the ones obtained through direct calculation and it is seen that they are in perfect agreement. The reflection coefficients that are obtained from the 3-D MoM procedure are used to calculate Green&rsquo / s functions that approximate electric field of an infinitesimal dipole on the periodically implanted substrate. Using the calculated Green&rsquo / s functions and the spectral domain MoM procedure, dispersion characteristics of a microstrip line on the periodically implanted substrate are obtained.

This doctoral thesis is focused on problems of modulators based on six-ports. It begins with description of current state of the art of six-ports used like modulators, their transfer functions and SIW technology. A design part of this thesis consists from experimental six-port based on substrate integrated waveguide (SIW) technology. There is presented step-by-step development of this six-port using this technology and also there is introduced micro-strip technology based six-port. Final design of six-ports and variable impedances were measured, the results are discussed and compared with expected ones in next chapters. Second part of this thesis deals with influences of internal parameters of six-ports to final signal transmission and derives theirs transfer functions for more than one reflection in structure. The computation results are compared with experimental measurements for fixed loads. With using of ideal loads sweeps, modulations with shaped input signals were calculated. For designed variables impedances, there was founded the optimal biasing points for demanded IQ diagram and discussed which from tested active circuit is suitable. In the last part there are shown results of experiment with these variable loads connected to both types of designed six-ports.