High-T/sub c/ superconducting high-Q coplanar resonator made on MgO

Coplanar two-port transmission line resonators were made using high-T/sub c/ superconducting EuBa/sub 2/Cu/sub 3/O/sub x/ film on an MgO substrate. The EuBa/sub 2/Cu/sub 3/O/sub x/ films were prepared by magnetron sputtering and patterned by photolithography and Ar ion milling. The resonator characteristics were measured as a junction of temperature and power. The highest unloaded Q value obtained was 12500 at 28 K and at 3.9 GHz, and the surface resistance of the film was estimated at about 40 mu Omega . No change in Q values was observed at input power level less than -20 dBm. >