Application of 3-D FEM/segmentation method to efficient design of cylindrical dielectric resonator filters

Microwave filter design may be done using a low pass prototype filter that provides to the designer with a circuit model, namely resonance frequencies and coupling factors, then actual resonators and coupling devices has to be physically implemented and interconnected to achieve such coupling and resonance values. This paper presents a design procedure, in a step by step basis, in which a segmentation method based on 3D finite element method is used to obtain the GSM (generalized scattering matrix) of building blocks in which the filter is divided. By linking the GSM of each block, the GSM of auxiliary structures are obtained. Circuit models for each structure are fitted to the full wave response and the actual synthesised values for coupling factors and resonances are determined.