Compact, high-Q, zero temperature coefficient, TE011 sapphire-rutile microwave distributed Bragg reflector resonators

Distributed Bragg reflector resonators (DBRR) have been initially suggested in order to improve the quality factor of sapphire loaded cavity (SLC) resonators. They were constructed from thin plates of sapphire designed to confine most of the energy of the resonant mode in free space. Q-factors larger than the dielectric loss limit of sapphire have been obtained using this method. However, these devices are necessarily larger than the whispering gallery (WG) resonators, as they require multiple layers to achieve sufficient confinement. Moreover, they are very sensitive to alignment and a special tool must be manufactured to properly construct the resonator. Finite element analysis of the structure has also revealed a large spurious mode density. Over 50 modes in a 1 GHz range at X-band were discovered. In this paper we introduce the concept of a compact solid microwave DBRR with reduced frequency temperature dependence and a Q-factor close to that of a pure sapphire resonator