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

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 1992-05, Vol.39 (3), p.405-411
• Main Authors: Driscoll, M.M., Haynes, J.T., Jelen, R.A., Weinert, R.W., Gavaler, J.R., Talvacchio, J., Wagner, G.R., Zaki, K.A., Liang, X.-P.
• Format: Article
• Language: English
• Subjects: Applied sciences; Circuit properties; Dielectrics; Distributed computing; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; High temperature superconductors; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Phase noise; Prototypes; Resonant frequency; Signal generators; Superconducting device noise; Superconducting films; Tellurium
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/58.143174

Ultra-high Q, X-band resonators, used in a frequency discriminator for stabilization of a low-noise signal generator, can provide a means of obtaining significant reduction in phase noise levels. Resonator unloaded Qs on the order of 500 K can be obtained in sapphire dielectric resonator (DR) operating on a low-order (i.e. TE/sub 01/) mode 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. Trade-off studies have been performed to select resonator dimensions for the optimum mode yielding highest unloaded Q and widest spurious mode separation. Field distributions within the resonator have been computed to enable practical excitation of the required mode. The results of both analysis and prototype device evaluation experiments are compared for resonators fabricated using enclosures consisting of conventional, metal sidewalls and covers employing HTS films as a function of cover conductivity.< >