Dual-Wideband Bandpass Filter Using Open and Shorted Stubs Loaded Ring Resonator

This letter presents a dual-wideband bandpass filter (BPF) by using open and shorted stubs loaded ring resonator. The resonator can excite multiple resonant modes. The transmission zeros (TZs) analyzed by the transversal signal interference concepts can divide the resonant modes into two groups that form dual-wide passband. The even-mode resonant frequencies can be controlled by the stubs parameters, and the TZs can be tuned by the port angle independently. So the center frequency (CF) and the bandwidth of each passband can be flexibly controlled. An experimental dual-wideband BPF with CF of 1.48/5.7 GHz and 3 dB FBW of 137.8%/49.3% is implemented, and the experimental results are presented for validation.