A High-performance Dual-band High Temperature Superconducting Filter at L-Band

This paper introduces an 8-pole high performance dual-band high temperature superconducting filter at L-band. Based on the stub-loaded resonators（SLRs）, broadening the bandwidth appropriately and introducing transmission zeros are used to meet the filter design requirements of band edge and group delay variation. The filter is fabricated on one side of double-side YBCO thin film with a 2-inch-diameter and 0.5-mm-thick MgO substrate by photolithography and ion etching technology. The measured results indicate that the 1 dB passband of the filter is 1 121～1 321 MHz and 1 527～1 648 MHz respectively. The out-of-band suppression is greater than 60 dB at 960 MHz and 1 900 MHz. The out-of-band suppression is greater than 40 dB at 1 360～1 460 MHz. The group delay variation of any 20 MHz in the passband is less than 4 ns. The filter circuit size with the feeders is about 19.02 mm×21.12 mm. The measured results are basically consistent with the simulated ones, which can meet the design requirements.