Analysis of multilayer microstrip filter by wave concept iterative process

An iterative method based on the concept of waves is presented to determine features of very high frequency´s electronic circuits in a planar wave guide. The analysis takes into account eventual coupling parasites. A two dimensional fast Fourier transformation algorithm is introduced to simplify-calculations and accelerate method convergence. The general formulation and the procedure of the iterative method implementation in frequency domain are described. In this article, the authors intend to study a double-layer dielectric substrate. This filter demonstrates the use of the third (vertical) dimension in the design of microstrip devices. The approach involves the mixed magnetic and electric filed equation technique and the wave concept iterative process which involves S-parameters extraction technique based on a simple form of matched toad simulation. In this sense, a program in FORTRAX has been elaborated to determine different parameters S_ij characterizing the studied structure. The numerical results are compared to results for microstrip structure and compared to those presented in other references. They show good agreement. The approach is demonstrated in detail for 2-port structures, with an outline of how it can readily be extended to the n-port case