An algorithm for tuning microwave resonator filters using short circuit admittance parameters

An analytic technique for tuning microwave cross-coupled resonator filters is presented. The method employs the short circuit admittance parameters of the filter, found through measurement to derive the coupling coefficients of the structure and hence the coupling matrix. Because several elements of distortion are unaccounted for in the ideal coupling matrix model, an error vector is derived and the Y-parameters are adjusted using vector operations to provide more accurate results. With the coupling coefficients found, the filter´s geometry can be accordingly adjusted and the process repeated until the filter is tuned. A numerical example is provided to illustrate the theory.