Miniature Wideband Superconducting Filter Design With Four Transmission Zeros Based on Quintuple-Mode Resonator (QMR)

This letter presents a high-temperature superconducting (HTS) wideband bandpass filter (BPF) based on quintuple-mode resonator (QMR). The connected resonator method (CRM) is employed to efficiently construct the multimode resonator. The proposed QMR generates two odd-mode frequencies and three even-mode frequencies, which collectively form the filter’s passband. To validate the proposed approach, one- and two-stage wideband filters are designed based on the QMR. Additionally, four transmission zeros (TZs) are strategically placed on both sides of the passband, significantly improving selectivity. By adjusting the geometrical parameters, these TZs can be controlled. The proposed wideband filter operates at 6.31 GHz with a fractional bandwidth (FBW) of approximately 78.3%. Measured results demonstrate excellent agreement with simulations, confirming the effectiveness of the design.