Design of Miniaturized Half Mode SIW BandPass Filter Using Metamaterial Unit Cell

This paper presents a new compact cross-coupled half-mode substrate integrated waveguide bandpass filter (HM-BPF) loaded by a novel complementary split ring resonator. The irregular impedance technique is used to miniaturize the physical size of the conventional elliptical shape CSRR. Therefore, the resonance frequency of the proposed E-CSRR unit-cell is decreased compared to the conventional CSRR with the same sizes. According to evanescent-mode propagation technique, by loading the complementary split-ring resonator (CSRR) on the metal surface of the substrate integrated waveguide (SIW) structure, an additional passband below the SIW cutoff frequency can be obtained. The proposed HM-SIW filter has a center frequency of 6.87 GHz, fractional bandwidth FBW of 7.6 %, a total size equal to 41.48 mm2 and pass-band width of 520 MHz. The filter exhibits two transmission zeros on the lower and upper side of the passband the transmission zeroes have been generated to improve the frequency selectivity.