Variation of resonant frequency of disk resonator coupled with external circuit.

A new analysis method for resonant characteristics that takes into account the effect from the external circuit on the whispering gallery (WG) mode dielectric disk resonator coupled electromagnetically with the external circuit is presented. The disk resonator is divided into the part not affected by the external circuit (uncoupled part) and the affected (coupled part). The variation of the phase constant in the coupled part is considered to alter the resonant frequency. In the analysis of the coupled part, the coupled transmission equation for the disk and the straight waveguide is solved approximately to obtain the distributed coupled characteristics. From the results, the equivalent circuit containing the coupled part is constructed and the resonant characteristics of the disk resonator are analyzed. In the numerical example, a rectangular dielectric waveguide is used as the external circuit, and the variation of the resonant frequency is computed as the gap between the disk resonator and the waveguide is varied. It is shown that the resonant frequency of the resonator can increase or decrease depending on the phase constant of the externally excited mode. Hence, useful data for accurate design are obtained for the WG mode dielectric resonator. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(11): 48–57, 1997 [ABSTRACT FROM AUTHOR]