A COMPACT WIDEBAND BANDPASS FILTER USING NOVEL CSRR LOADED QMSIW RESONATOR WITH HIGH SELECTIVITY.

A novel quarter-mode substrate integrated waveguide (QMSIW) resonator with back-to-back triangular complementary split-ring resonators (CSRRs) etched on the waveguide surface is proposed in this paper. The proposed CSRR structures allow the implementation of a forward-wave passband propagating with high selectivity below the characteristic cutoff frequency of the conventional QMSIW. Utilizing the property of flexible open structure on QMSIWs' two sides, a cascaded quadruplet (CQ) bandpass filter (BPF) using the proposed QMSIW resonator and proximity coupling structure is presented. Compared with some other reported BPFs with SIW technique, the presented BPF using the novel QMSIW resonator has great improvements on size reduction and selectivity, simultaneously, with simple geometry. At the center frequency of 3.7GHz, the designed BPF filter achieves a wideband with a fractional bandwidth up to 24.3% and a high selectivity with a shape factor of 1.23. The compact dimension of this filter is as small as 0.36λ_g x 0:36λ_g, where λ_g is the guide wavelength at the center frequency. The proposed filter is simulated, fabricated and tested. The measured results are in good agreement with the simulation. [ABSTRACT FROM AUTHOR]