HIGH-RESOLUTION MEASUREMENT OF THE TEMPERATURE-DEPENDENCE OF THE Q, COUPLING AND RESONANT-FREQUENCY OF A MICROWAVE RESONATOR

An automated system is described which facilitates fast high-resolutio n measurements of Q, coupling and resonant frequency of modes in a mic rowave resonator. We demonstrate measurements of Q and coupling with a resolution of 6 x 10(-4) and a fractional frequency measurement resol ution of 3 x 10(-13). The system is used to measure the temperature-de pendence of the mode Q, coupling and resonant frequency for modes in t wo high-Q cryogenic sapphire resonators. Measurement of the temperatur e variation of Q is used to estimate the geometric factor, which is a measure of the mode energy confinement to the sapphire element distrib ution. Measurement of the mode frequency temperature-dependence can be used to determine the effect of paramagnetic impurities in the sapphi re.