Microwave measurement of surface impedance of high-T/sub c/ superconductor

Perturbation formulas for a TE/sub 011/ mode dielectric resonator and for a TE/sub 011/ mode circular cavity are derived to determine the surface impedance, z/sub s/, of superconductors from measured values of resonant frequency and unloaded Q. The Z/sub s/ values for a YBCO plate with a diameter of 30 mm were measured at 8.7, 10.4, and 23.7 GHz using these formulas. The measured results are presented as functions of temperature.<
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