UHF band switchable superconducting filter with pin diode switches

A low-loss switchable superconducting filter is presented. High Q resonators loaded with switchable superconducting interdigital capacitors are introduced. A two-pole 2-bit switchable high-temperature superconducting (HTS) filter at 516 MHz with a bandwidth of 29 MHz is designed and fabricated. The measured centre frequency tuning range is 33 MHz (6.4%). In all states, the HTS filter with pin diode switches exhibits an insertion loss <0.81 dB and a good return loss better than 16.8 dB.