General optimization algorithm for reduction of coupling matrix of chebyshev filtering functions

Abstract

An optimization algorithm for reduction of coupling matrix to desired waveguide filter topology is proposed and implemented in software tool. With this optimization algorithm developed; the designer is only required to input the initial coupling matrix and desired filter topology. This algorithm automatically finds the rotation angle and rotation sequence to generate desired topology coupling matrix. This algorithm is based on minimization of the error function between the initial coupling matrix and the desired topology coupling matrix. It works in two steps; in first step; pivot angle and pivot element that can reduce the error function is searched roughly. In the second step; pivot angle minimizing the error function is searched very precisely in the vicinity of angle found in step 1. This process is repeated iteratively until error function up to the desired level is achieved. The algorithm can generate waveguide filter configurations like folded, inline, pfitzenmaier, quasi-pfitzenmaier, arrow, cascaded quartets; cascaded trisection, Cul-De-Sac and box section. Three examples are included to demonstrate the excellent performance of the algorithm presented. The response of the initial coupling matrix and desired coupling matrix were found exactly same.