| Abstract: | This article designed a five‐order narrow‐band tunable superconducting filter. The superconducting microstrip circuit was loaded by varactors diode. The center frequency of the tunable can be tuned through the changing of the bias voltage added in the varactors diode. The whole device has a parallel coupling structure and the filter circuit was fabricated by DyBa2Cu3O7 superconducting film with 0.5 mm thickness and 2 in. LaAlO3 as the substrate. The frequency can be continuously adjusted from 235 MHz to 250 MHz. The insertion loss of the filter was in the range of 2.51 dB to 9.64 dB. The bandwidth of the tunable filter was in the range of 0.5 MHz to 0.9 MHz. The out‐of‐band rejection was better than 70 dB. The measured results are in good agreement with the simulated ones. |
