A hybrid computer-aided tuning method for microwave filters with asymmetrical phase shift effects

A hybrid tuning method for microwave filters with asymmetric phase shift effects is presented in this paper. This novel tuning technique is based on the combination of the modified Cauchy method and aggressive space mapping (ASM) technique. After remove the phase shift effect, Cauchy method is applied to determine the characteristic polynomials of the filter's response. Then the parameters (coupling matrix) of the low-pass prototype is extracted from the characteristic polynomials. The aggressive space mapping is used to optimized the fine model to guarantee that each step of a tuning is always in the right direction. The validity is verified by a fourth order Chebyshev filter tuning example.