High T/sub c/ superconductor-sapphire microwave resonator with extremely high Q-values up to 90 K

Several high-temperature-superconductor-sapphire TE/sub 011/ mode resonators were designed, fabricated, and tested. At 5.552 GHz, Q/sub 0/ reached 2*10/sup 6/ at 90 K, 3*10/sup 6/ at 80 K, and 1.4*10/sup 7/ at 4.2 K with circulating power up to 500 kW. Formulas for calculating the resonant frequency and Q-value were derived. These theoretical results showed good agreement with the experimental measurements. Applications such as frequency-stabilized oscillators and filters, and the characterizations of high-temperature superconductor films are discussed.<
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