Miniaturized half mode substrate integrated waveguide cavity resonator and filter with good spurious suppression

Abstract

A miniaturized cavity resonator based on the half mode substrate integrated waveguide (HMSIW) technology is proposed and investigated in this paper to reduce the circuit area of a conventional substrate integrated waveguide (SIW) cavity resonator much more. Such a miniaturized resonator is built up by a two-layer HMSIW cavity loaded with a modified complementary split ring resonator (CSRR) etched on its middle conductor plate. Then, the proposed miniaturized cavity resonator is employed to design an S-band fourth-element bandpass filter. The center frequency is 3 GHz and the average insertion loss is 1.2 dB within the in-band. The total circuit area is only , i.e., 7% of the size of a conventional SIW fourth-element bandpass filter. It presents a good and wideband spurious suppression because the first higher order resonant mode of the used resonator is far away from the operation band. Experimental and simulated results are in good agreement, both validating our design concept.