A compact double folded quarter mode substrate integrated waveguide (DFQMSIW) filter

Abstract

A novel double folded quarter mode substrate integrated waveguide (DFQMSIW) resonator is proposed. The dominant resonant mode of the proposed resonator is TE₁₀₁ mode. The size of the DFQMSIW cavity is reduced nearly by 94% compared with the conventional SIW cavity. A three order cascaded DFQMSIW filter with a center frequency of 2.84 GHz and a fractional bandwidth of 11.5% is implemented. The measured results show that the filter insertion losses are below −1.8 dB and return losses are better than −15 dB. Good agreement between simulated and measured results demonstrates the validity of the proposed method.