Size-reduced dual-band HMSIW cavity filters loaded with double-sided SICSRRs

Two size-reduced dual-band half-mode substrate integrated waveguide (HMSIW) cavity filters double-side-loaded with the conventional and stepped-impedance complementary split-ring resonators (SICSRRs) are presented. The SICSRR can exhibit larger equivalent electrical length than the conventional CSRR and thus provides a method to implement size-miniaturisation. By loading both CSRR and SICSRR into the two sides of the HMSIW cavity, a dual-band resonator is formed. Since sizes of the CSRR and SICSRR on the two sides are controlled independently, the two passbands of the proposed resonator can be tuned flexibly. With the proposed HMSIW-DS-SICSRR cavity resonators, two dual-band filters are realised. Compared to other dual-band SIW filters, the two proposed dual-band filters can achieve sized-reduction about 48.5 and 50%, with the measured results in good agreement with the simulated ones.