Temperature compensated cryogenic whispering gallery mode resonator for microwave frequency standard applications

We have investigated a miniature composite dielectric resonator employing a sapphire puck and a single crystalline platelet of rutile, excited in a wh ispering gallery mode. Modeling of the relative filling factors of the diel ectric components is in good agreement with experiment. The loaded Q value at 17 GHz is as high as 3 x 10(6). We have achieved values of the square-ro ot of the,Wan variance as low as a x 10(-12) for an integration time of 100 0 s with the prototype system, The high Q resonator can also form the basis for a low-phase noise oscillator and we present data for the measured spec tral density of phase noise.