Design of Parallel-Coupled Dual-Mode Resonator Bandpass Filters

A circuit model for dual-mode resonators is proposed to develop a design procedure that facilitates the design of parallel-coupled dual-mode resonator filters. Based on the design procedure, a parallel-coupled dual-mode resonator filter can be designed in a way similar to the design of parallel-coupled line filters. Compared to the parallel-coupled line filter that uses half-wavelength line resonators, the use of dual-mode resonators not only achieves smaller size and better performance, but does not complicate the design and fabrication processes, as demonstrated in this paper. Accordingly, the parallel-coupled dual-mode resonator filter can be a good candidate for many practical applications that accept the Chebyshev or Butterworth response.