Computer-aided tuning and diagnosis of microwave filters using sequential parameter extraction

This paper describes an approach to the computer-aided tuning of multiple-coupled resonator filters. The method is based on a sequential parameter extraction and tuning process and employs three different filter models. A detuned model represents the initial status of the filter after a well defined detuning procedure. The target filter is described by the ideal model, whereas the actual state of the filter at each tuning step is represented by a coarse adaptive model. The goal of the procedure is the convergence of the coarse model to the ideal model and will be obtained by systematically centering resonant frequencies and coupling coefficients. Two practical examples comprising a low- and a high-degree filter confirm the effectiveness of the proposed approach.