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

This article presents a novel dual-band high-temperature superconducting(HTS) 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 GHz 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 70K with insertion losses as low as 0.16 dB and 0.09 dB, return losses better than 15.16 dB and 20.10 dB for the respective bands, and excellent agreement between simulated and measured responses