Accurate rational model extraction method for lossy filter based on modified Cauchy method

A lossy filter rational model extraction technique based on modified Cauchy method is presented in this paper. The conventional Cauchy method is only for lossless case, not suitable for lossy filter. The rational polynomials model is the prerequisite to synthesize the low-pass prototype (the evaluation of the coupling matrix) for computer-aided tuning. To this purpose, we modify the conventional Cauchy method to extract the accurate rational model of lossy filters. Three numerical examples verify the new technique successfully.