Mixed Electric and Magnetic Coupling Design Based on Coupling Matrix Extraction

Abstract: This paper proposes a design and fine-tuning method for mixed electric and magnetic coupling filters. It derives the quantitative relationship between the coupling coefficients (electric and magnetic coupling, i. e., EC and MC) and the linear coefficients of frequency dependent coupling for the first time. Different from the parameter extraction technique using the bandpass circuit model, the proposed approach explicitly relates EC and MC to the coupling matrix model. This paper provides a general theoretic framework for computer-aided design and tuning of a mixed electric and magnetic coupling filter based on coupling matrices. An example of a 7th-order coaxial combline filter design is given in the paper, verifying the practical value of the approach.

Keywords: coupling matrix; frequency-dependent coupling; mixed electric and magnetic coupling; parameter extraction