This paper presents RF power properties of YBCO films on LaAlO3 substrate examined using microstrip disk shape-patterned resonators for around 4 GHz. Characterization of the YBCO films for the resonators was carried out. For input-output power measurement, the resonators with the condition of strong I/O couplings were designed and fabricated. The RF power properties of the resonators at cryogenic temperatures were measured. The resonator condition to obtain the handling power over 10 W at 30 and 70 K was confirmed. The temperature dependence of the break-down powers at 4 GHz for the resonators showed two broad peaks. We discuss the unique phenomenon with magnetic flux model, as referred to the YBCO films characteristics results.

This paper reports the design and fabrication of a miniaturized superconducting microstrip line filter using YBCO film on MgO. The filter's resonators are shaped in a double spiral, and the size of the resonators is optimized from the standpoint of the unloaded Q-factor. The 15-pole bandpass filter that has the center frequency of 1.95 GHz and the bandwidth of 20 MHz is designed in the size of 9.7 44 mm. The simulated S-parameter characteristics of the filter is corresponding to the initial design parameters. We fabricated the filter on an MgO substrate with a diameter of 2 inches. The filter had very sharp cutoff and a very low insertion loss of 0.14 dB.