Wideband bandpass filter using symmetric multimode resonator

Abstract

A novel wideband bandpass filter using a symmetric multimode resonator is proposed. A wide passband with two transmission zeros near the passband is realised by changing the characteristic impedance of the multimode resonator, and the bandwidth of the five-order passband with even/odd-modes can be adjusted. A planar wideband bandpass filter prototype with 3 dB fractional bandwidth of 62.7% is designed and fabricated.