Coupling of dual modes in a dielectric waveguide resonator and its application to bandpass filters

A high-permittivity ceramics (¿ r=93)is used to fabricate a rectangular waveguide resonator of square cross section. Two degenerate TE101 and TE011, -like mode of the ¿/4 resonator is coupled each other through various perturbations such as a corner cut, a current path on the open end face or a slit on the shorted end face. Excitation of the resonator is also of many kinds, resulting in much option for the BPF configuration. A two-stage BPF is designed using the experimental results on the coupling factor and external Q. It is mounted on a printed circuit board with 3.3GHz of the center frequency and 30MHz of the bandwidth.