An automated design technique for asynchronously-tuned circular waveguide dual-mode filters

This paper presents an automated design technique for circular waveguide dual-mode filters. This new method systematically designs each coupling element of a dual-mode filter by matching the Generalized Scattering Matrix (GSM) only at the center frequency. A unique iterative method is brought up to accurately calculate the degenerate modes coupling as well as their insertion phases. Besides, self-couplings in the coupling matrix (CM) that account for the detuned frequencies for asynchronously-tuned filters are also fully taken into account. Without any post-adjustments or optimizations, the whole auto-mated design process is extremely fast yet precise. One multiplexer design example is also presented, showing an excellent result of a designed electromagnetic (EM) model as compared to the desired circuit model responses.