A novel dual-band bandpass SIW filter loaded with modified dual-CSRRs and Z-shaped slot

Abstract

In this paper, a novel dual-band bandpass substrate integrated waveguide (SIW) filter has been presented by loading two modified dual complementary split ring resonators (CSRRs) and a Z-shaped slot on the top side of SIW. The modified dual-CSRR structure is obtained by folding its outer ring, adding T-shaped branch to its inner ring and placing the splits of the inner and outer rings of CSRR in the same direction. The modified structure allows the electromagnetic wave to propagate in the passband below the cutoff frequency of the waveguide. Compared with conventional CSRR of the same size, it has two passbands and work at a lower frequency. A dual-band bandpass filter is proposed by placing two proposed dual-CRSSs face-to-face on the top side of SIW. In order to improve the performance of the filter, the Z-shaped slot is introduced to enhance the electromagnetic coupling, thus increasing the transmission zero point, broadening the passband and enhancing the flatness in the band, and realizing the center frequency shift of the passband to the left. To validate the design and analysis, a dual-band bandpass SIW filter loaded with two modified dual-CSRRs and a Z-shaped slot is manufactured and measured. The first pass band of the filter has a center frequency of 1.94 GHz, a 3 dB band width of 0.28 GHz, the second pass band has a center frequency of 4.85 GHz and a 3 dB band width of 0.13 GHz, which is basically consistent with the simulation results.