Narrow band pass filter pass filter fabricated by YBCO high temperature superconductor

摘要

We have designed and fabricated high temperature superconductor (HTS) five-pole narrow band pass filter using hairpin resonator structure. A 700nm YBCO film was deposited on LaAlO{sub}3 substrate by e-gun co-evaporation. The proposed structure provided more compact size than conventional parallel-coupling filters. The designed filter with 1.3% narrow bandwidth was operated at the central frequency of 3GHz. A maximum 0.123dB insertion loss and minimum 18dB return loss of the filter was obtained after trimming. The RF properties were extracted by the microstrip line resonator method. The extracted Q factor was up to 8200 at T=77K. The material characteristics of YBCO thin film have been investigated by XRD and AFM. The obtained T{sub}c was about 90K and the transition range of the temperature was less than 0.5K.