A Novel Approach to Ring Resonator Theory Involving Even and Odd Mode Analysis

This paper presents a novel theoretical approach to the analysis of a ring resonator consisting of an edge-fed circular microstrip of arbitrary width on a substrate over a ground plane; the analysis takes into account the existing coupling between the two halves of the ring. The proposed theory, based on the ordinary quasi-transverse electromagnetic approach, makes use of multiconductor modal analysis tools where azymuthally coupled even and odd modes play a key role. Results concerning ring voltages and currents, ring input impedance, and ring resonance frequencies are developed. Novel results are compared with those obtained by using the standard approach valid for narrow strip. Radiation effects have been neglected.