Cooled, ultra-high Q, sapphire dielectric resonators for low noise, microwave signal generation

It is shown that with high-quality, large-area YBCO films and simple, styrofoam mounts, unloaded X-band Q values of over 250 thousand are attainable for TE₀₁ mode operation of a sapphire dielectric resonator (DR) operated at 77 K and employing high-temperature superconducting (HTS) films installed in the DR enclosure covers. Rigorous analysis for the determination of resonator frequency, modes, and unloaded Q have been carried out using mode matching techniques. The results of both analysis and prototype device evaluation experiments are compared for resonators fabricated using enclosures consisting of conventional metal sidewalls and covers using HTS films as a function of cover conductivity