Extremely high-Q factor dielectric resonators for millimeter-wave applications

It has been proven, based on a rigorous electromagnetic analysis, that spherical TE/sub 10p/-mode Bragg-reflection resonators exhibit many times higher Q factors than corresponding cylindrical TE/sub 01/spl delta//-mode dielectric resonators, dielectric whispering-gallery-mode resonators, or empty spherical TE/sub 10p/-mode cavities. Rigorous equations have been derived that allow optimally designed Q-factor and "quarter-wavelength" reflector-multilayered-spherical Bragg-reflection resonators. Experiments have been performed on three-layer spherical resonators made of single-crystal YAG and single-crystal quartz. The unloaded Q factor for the TE/sub 012/ mode in these resonators was 1.04/spl times/10/sup 5/ at 26.26 GHz for YAG and 6.4/spl times/10/sup 4/ at 27.63 GHz for quartz.