10 GHz YBa sub 2 Cu sub 3 O sub 7-- delta Superconducting Ring Resonators on NdGaO sub 3 Substrates

YBa sub 2 Cu sub 3 O sub 7-- delta thin films were formed on NdGaO sub 3 substrates by laser ablation. Critical temperatures > 89K and critical current densities > 2 x 10 exp 6 A cm exp --2 at 77K were obtained. The microwave performance of films patterned into microstrip ring resonators with Au ground planes was measured. An unloaded quality factor six times larger than that of a Au resonator of identical geometry was achieved. The unloaded quality factor decreased < 70K for both the superconducting and Au resonators due to increasing dielectric losses in the substrate. The temperature dependence of the loss tangent of NdGaO sub 3 was extracted from the measurements.