Design and performance of dual-band high temperature superconducting filter

In this paper, a dual-band high temperature superconducting (HTS) filter with 14-pole and 3 cross couplings is presented. The equivalent model, theoretical result, coupling matrix, and the simulated result of the filter are demonstrated. The desired filter is designed and fabricated using double-sided DyBa2Cu3O7 thin films on MgO wafer 2 inches in diameter and 0.5 mm in thickness. The filter has two passbands with frequencies 1920-1940 MHz and 1960-1980 MHz respectively, and insertion loss less than 0.2 dB. The measurement results show that the response of practical filters is in good agreement with that of simulated results and theoretical analysis, with the group delay variation being less than +/- 20 ns over 90% of the filter bandwidth for the two passbands.