Novel temperature control of a sapphire loaded cavity oscillator from the difference frequency of WGE and WGH modes

Abstract

Novel temperature control circuits have been designed to stabilize the temperature of a Sapphire Loaded Cavity (SLC) Whispering Gallery resonator-oscillator and improve its medium-term frequency stability. The temperature control sensor operates from the difference frequency between Whispering Gallery quasi-TE (WGH) and quasi-TM (WGE) modes (dual-mode operation), which have different temperature coefficients of frequency due to the anisotropy of sapphire. The design concept was verified at room temperature at 9 GHz with a SLC resonator capable of supporting two orthogonal modes (the WGE/sub 7,0,0/ and the WGH/sub 9,0,0/) separated by 79 MHz. A discussion of the noise performances of different configurations of dual-mode SLC oscillators is presented.