Praveena, NamanathanGunavathi, N2026-10-312026-10-312023-03-1819376480http://dx.doi.org/10.2528/PIERL22122008http://nitt.ndl.gov.in/handle/123456789/371A narrowband, high selectivity Substrate Integrated Waveguide (SIW) bandpass filter with perturbing vias and CSRR is proposed for Sub-6 GHz applications. Firstly, the perturbing vias are positioned at the symmetrical axis of the SIW cavity which produces distinct electric field distribution for the first two modes. Next, the ground plane is engraved with the CSRR placed at an offset distance on either side of the perturbing vias, forming the coupling arrangement that combines mixed and magnetic, electric coupling. The presence of CSRRs resulted in a narrowband filter. The filter's center frequency is 4.947 GHz with a fractional bandwidth of 1.16%. By comparing the fabricated filter to an existing SIW conventional multi-cavity or cascaded resonator, a size reduction of 117% is achieved. The simulated and measured results agree with each other.enArticle