Investigation of Microwave Dielectric-ResONATOR Filters.

摘要

Waveguide band-stop filters using dielectric resonators are considered. Two basic orientations, transverse and axial, of a dielectric resonator in a TE10-mode rectangular waveguide are analyzed. Formulas for external Q are derived in both cases. The experimental response of a three resonator band-stop filter is shown to agree well with the theoretically anticipated performance. Various configurations of dielectric resonators in waveguide that yield directional filter performance are described. Pairs of resonators operating in their fundamental mode are used as well as a single resonator operating in its second mode of resonance. Formulas are derived for several cases. Measured resonant frequency curves are presented for the first three modes of a disk as a function of length-to-diameter ratio and favorable regions of L/D yielding good mode separation are found for the cases of the first and second modes. Data showing the effect of metal-wall proximity on unloaded Q and resonant frequency are presented for an axially oriented dielectric disk in square and circular tubes below cut-off. (Author)