Phase De-Embedding of Narrowband Coupled-Resonator Networks by Vector Fitting

This paper introduces a simple and effective way to de-embed the constant phase loading and transmission line from the simulated or measured S-parameter data of a narrowband coupled-resonator network by vector fitting. The phase-corrected S-parameters can be converted to Y-parameters to prepare for rational function approximation and extraction of the coupling matrix for the purpose of computer-aided tuning. This method is applicable to many narrowband coupled-resonator networks including microwave bandpass filters and diplexers. Examples including a simulated triple-mode bandpass filter and a measured wire-T junction diplexer are given to demonstrate the effectiveness of the new technique.