Generation of accurate rational model of microwave filters using Cauchy-TLS method

A method to generate an accurate rational model of microwave coupled resonator filters is presented. The Cauchy-TLS (total least squares) method has been used to achieve this goal. By the analysis of the relationship between the polynomial coefficients and the phase loading, it is easy to remove the loading effect. The resulting model can be used to extract the coupling structure of filters by synthesis or optimization. Two numerical examples are presented to validate the proposed method. One deals with numerical simulation data from a full-wave electromagnetic simulation and the other uses the measured data.