High performance distributed Bragg reflector microwave resonator

摘要

A new resonator device structure is described that achievesnQ-factors well above those currently realizable for conventional roomntemperature microwave structures. The new structure consists of anmicrowave cavity, for which the enclosure walls consist of distributednBragg reflectors (DBR) made of low-loss sapphire. For thisnconfiguration, most of the resonant field resides in empty space, withnsmall field strengths in the thin layers of sapphire which comprise thenDBR structure. The physical structure takes the form of interpenetratingnconcentric rings and plates of low-loss sapphire contained in ancylindrical metal enclosure. The theoretical analysis of the DBRnresonant structure allows the positions and dimensions of the componentnrings and plates to be precisely determined for a specified resonantnfrequency. The resonator Q can be accurately calculated, and plots ofnthe resonant fields clearly show the physical mechanism leading to thenobserved efficiency of this resonator structure. Experimental resultsnare given for resonators designed at 9.0 and 13.2 GHz. The measurednunloaded Q's at room temperature are over 650000 and 450000,nrespectively