Unloaded Qs of axially asymmetric modes of dielectric resonators

The resonant frequencies and unloaded Qs of hybrid modes on cylindrical dielectric resonators in conducting enclosures are studied. The formulation uses the mode-matching technique and includes axially symmetric (TE/sub 0m/ and/or TM/sub 0m/), as well as axially nonsymmetric hybrid (HE/sub nm/) modes, which could exist in dielectric-loaded waveguides. The structures analyzed can simulate resonators on microstrip substrates. The losses in both the conducting walls and the dielectric material and the stored energy in the general resonator are obtained. Mode amplitudes determined from the solution of the boundary value problem by mode matching are used to rigorously compute the unloaded Qs of the resonators. Numerical results in the millimeter-wave range are presented for the unloaded Qs of various modes as a function of the resonator parameters. The effects of losses on the resonator wall are discussed, and methods of improving the unloaded Qs are explored. The method was applied to a 33 GHz resonator on GaAs, alumina, and quartz substrates, and the results verify the accuracy of the model used and the numerical computations.<>