Diagnosis of lossy resonator filters with sourceLoad coupling using Y-parameters
This article presents a novel approach to extract the coupling matrix (CM) of a lossy cross-coupled resonator bandpass filter with sourceload coupling using admittance parameters (also known as Y-parameters). The Y-parameters are calculated by characteristic polynomials corresponding to the measured S-parameters. The unloaded quality factor of resonators and the CM can be extracted from the Y-parameters. The method allows one to diagnose a filter with sourceload coupling without necessity of dealing with the degenerate poles problem of the Y-parameters and the measurement noise. The proposed diagnosis method can be used in a filter tuning and speeds up its physical realization. The method is verified by a fabricated fourth-order bandpass filter and a simulated substrate integrated waveguide dual-mode filter with sourceload couplings.  2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:713717, 2014.
extraction coupling matrix bandpass filter unloaded q filter diagnosis