Filter Design of SIW Loaded by Circular Complementary Split-Ring Resonant

This paper presents a substrate integrated waveguide (SIW) filter using a circular complementary split-ring resonator (CSRR) structure etched in its surface. By capitalizing on the high-pass characteristics of SIW and the zero and pole generated by CSRR, a broadband performance is achieved. Furthermore, the CSRR elements are arranged vertically, and a groove-type coplanar waveguide (CPW) transition structure is employed to reduce size, resulting in a compact and miniaturized broadband filter is designed by using the wafer-level package (WLP) process. The measurement results demonstrate a passband width of $30-43 \mathrm{GHz}$, an in-band return loss is less than $16 \mathrm{~dB}$. The filter is suitable for applications in radar communication and so on.