Design and performance of a 6-pole ultra-narrow band high temperature superconducting filter

In this paper, a 6-pole ultra-narrow band high temperature superconducting (HTS) filter is presented. The equivalent model, theoretical result, coupling matrix, simulated result and the layout of the filter are demonstrated. A desired filter is designed and fabricated using double-sided DyBa 2 Cu 3 O 7 thin films on 2-inch diameter and 0.5 mm thickness MgO wafer. The fractional bandwidth of the filter is only 0.58‰ insertion loss is less than 0.6 dB and the out-band rejection is more than 70 dB. The measurement results show that the response of practical filters is in good agreement with the simulated results.