Compact superconducting single- and dual-band filter design using multimode stepped-impedance resonator**Project supported by the National Natural Science Foundation of China (Grant No. 61371009) and the Fund from the Chinese Ministry of Science and Technology (Grant No. 2014AA032703).

Abstract

This study presents two multimode stepped-impedance structures to design single- and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth (FBW) of 25.6%. Four stubs (two low frequency and two high frequency ones) are connected to the rectangular patch in the center to construct a quadruplemode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single- and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.