2018 Volume 15 Issue 5 Pages 20180059
A miniaturized dual-band bandpass filter (DBPF) using a pair of composite resonators is proposed in this letter. The composite resonator consists of two vertical short-circuited microstrip lines and a short transversal microstrip line, and its resonant characteristics are analyzed by using the even- and odd-mode method. The even- and odd-mode of the resonator can be controlled individually readily, and hence the DBPF can be designed with a flexible frequency ratio. The DBPF has a compact size of 0.06 λg × 0.14 λg. To verify the design, a compact DBPF with 3-dB fractional bandwidths of 6% and 7% is designed and fabricated. The measured response is in good agreement with the simulated result.