In order to improve the design efficiency of microwave bandpass filters,an optimization design method is proposed based on the parameter extraction and the space mapping. In this method,first,the Cauchy-TLS ( Total Least Squares) method is used to obtain the rational fraction models of the filters. Next,by using these models,a fast convergent objective function is constructed to extract the equivalent circuit parameters. Then,according to the
principle of the space mapping,the problem of solving the optimal physical dimension of the filter is transformed into a quadratic constrained optimization model,and the corresponding solution is used to guide full-wave simulation of the filters. Finally,a dual-mode circular-waveguide filter is designed and machined,and its optimal physical dimension with ideal response is achieved after six iterations. It is found that the measured results accord well with the simulated ones.