Analysis of resonant characteristics for a one-wavelength ring resonator coupled with two orthogonal resonant modes

In a one-wavelength ring resonator formed by a transmission line, there exi st two orthogonal modes. In this paper, an excitation method for these orth ogonal resonant modes is explained. In addition, the coupling between the o rthogonal resonant modes, which is important for applications, is considere d in detail. An analysis method is presented for the coupling factor betwee n the modes, and the attenuation poles generated by the present configurati on. Further, an analysis and an experimental investigation are carried out in the case where the open stub and the impedance step are used for configu ration of coupling between the modes. The validity of the proposed analysis method is shown and the fundamental characteristics of filter synthesis ar e obtained. (C) 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(9): 19-28 , 1999.