MM/FE/FD CAD Method for the Optimization of Waveguide Filters Including Structures of Arbitrary Shape and Coax Feeds

A fast full-wave CAD method is described for the accurate design and optimization of advanced waveguide components including cross-sections, planar structures, or 3D elements of arbitrary shape as well as coax feeds. The method is based on the combination of the mode-matching (MM) technique with the 2D finite-element (FE) and the 3D finite difference (FD) algorithm, which unites advantageously the flexibility of the FE and the FD methods with the efficiency of the MM technique. Typical design examples such as H-plane iris filters cut in the E-plane with finite radii and filters fed by coaxial waveguides demonstrate the usefulness of the presented CAD tool. The theory is verified by measurements.