HTS microstrip filters using H-type resonators

We report the characteristics of a high-T/sub c/ superconductor (HTS) bandpass filter with the designed center frequency of 16.5 GHz. A YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) superconducting thin film was prepared using the rf-magnetron sputtering deposition technique. The filter used in this work was composed of the "H"-type resonator (non-uniform microstrip lines). This approach has advantages for a considerably high Q-value and the compact filter structure. The impedance ratio of the "H"-type resonator was 0.5 in this work. In the measured responses, this HTS filter showed the insertion loss of -0.4 dB at maximum. The measured center frequency of our HTS bandpass filter was 16.44 GHz and the passband was from 15.91 GHz to 16.97 GHz, a bandwidth of 6.86% with 3 dB in band Chebyshev ripple. Experimental results of our filters were reported in terms of insertion loss, return loss and other various characteristics.