Determining resonant frequencies of single dual-mode resonator and its application

In this paper, determining the resonant frequency for the bandpass filter using single dual-mode resonator is proposed. A coupling coefficient implies the information which is the positions of poles for the filter. Therefore, we can obtain the resonant frequencies (f_e, f_m) from the above information and the analysis of the equivalent circuit. These resonant frequencies are determined to even-mode resonant frequency f_even and odd-mode resonant frequency f_οdd according to the position of the transmission zero. In order to verify the theory, the bandpass filter using the single dual-mode resonator of simple structure is designed and fabricated.