Multiple-Mode Wideband Bandpass Filter Using Split Ring Resonators in a Rectangular Waveguide Cavity

Abstract

This paper presents a simple split ring resonator excitation to realize a multi-mode wideband bandpass filter in a rectangular waveguide cavity. The proposed resonator employs two rectangular split rings attached with two coaxial probes extended into the cavity to excite two resonant modes, unlike the conventional cavity resonators which employ conductive cylinders in the cavities to achieve the same results. A hybrid magnetic (HM) mode and a hybrid electric (HE) mode are the two hybrid modes excited to realize the wideband bandpass filter. The filter operates at 2.5 GHz center frequency with 53% fractional bandwidth. Finally, the prototypes of a second and a fourth order filter are fabricated for results validation. Measured results are in good agreement with the simulated ones.