High Selectivity, Dual-Mode Substrate Integrated Waveguide Cavity Bandpass Filter Loaded Using CCSRR

Abstract

In this paper, a third-order, high selectivity Substrate Integrated Waveguide (SIW) bandpass filter (BPF) loaded with Circular Complementary Split-Ring Resonator (CCSRR) is proposed for C band applications. The SIW cavity BPF comprises two stepped resonators ([Formula: see text] and [Formula: see text]) and one CSRR ([Formula: see text]) engraved on the top metal plate. Initially, the cavity loaded with stepped resonators ([Formula: see text] and [Formula: see text]) alone does not make a good selectivity on the lower out of band. Hence, the CCSRR is introduced between the stepped resonators ([Formula: see text] and [Formula: see text]) to improve the filter’s selectivity and enhance the filter’s bandwidth. The introduction of CCSRR enhances the selectivity on the lower out-of-band at 5.5[Formula: see text]GHz, and the extra pole increases the bandwidth. The metamaterial behavior of CCSRR is validated by permittivity extraction. The 3[Formula: see text]dB bandwidth of the third-order SIW filter is 840 MHz with a center frequency of 6.18[Formula: see text]GHz. The designed filter uses RTDuroid 5880 substrate of [Formula: see text] = 2.2 with a size of 28.4 [Formula: see text] 28.4 [Formula: see text] 0.51[Formula: see text]mm3. The proposed filter measurement and simulated results agree with each other.