Design of Multitransmission Zero HTS Dual-Passband Filter With Independent Adjustment of Passband Characteristics

Abstract

This article presents a novel dual-band high-temperature superconducting filter based on an innovative parallel dual-mode resonator configuration that fundamentally differs from conventional cascaded designs. The proposed architecture employs a unique feeder–resonator coupling scheme to achieve complete electromagnetic isolation between passbands while enabling independent control of center frequencies at 2.58 and 4.38 GHz, bandwidths of 17% and 13%, and transmission zero locations. The compact design realizes three transmission zeros using only two second-order resonators through optimized structural parameters that completely eliminate inter-band coupling effects. Fabricated on 0.5-mm MgO substrate with double-sided YBCO films, the filter demonstrates outstanding performance at 70 K with insertion losses as low as 0.16 and 0.09 dB, return losses better than 15.16 and 20.10 dB for the respective bands, and excellent agreement between simulated and measured responses.