High-Performance Compact Multi-Mode UWB Filter using High-Temperature Superconductivity

A high-performance miniaturized multi-mode ultra-wide band (UWB) filter is proposed in this paper. The simple compact quintuple-mode resonator is constructed by loading three sets of open stubs on a modified conventional triple-mode resonator. Even and odd mode analytical methods are applied to analyze it. In addition, the function of each part of the filter is studied in cases of weak/strong coupling. In order to further improve the insertion loss, selectivity and out-of-band suppression, the designed filter is finally fabricated on double-sided YBCO/MgO/YBCO high-temperature superconducting (HTS) film. The test results show that the HTS UWB filter has excellent performance, and the simulation results are in good agreement with the test ones. The 3-dB bandwidth covers 3.6 ~ 13.2 GHz. The maximum insertion loss in the band was only 0.32 dB, and the reflection was better than -15.1 dB. The band-edge roll-off rate was 56 dB/GHz and the upper stopband with 20 dB rejection extended to 20.7 GHz.