Wideband and Wide-Angle FSS Based on Quarter-Mode Substrate Integrated Waveguide Technology

A substrate integrated waveguide (SIW) cavity-based frequency selective surface (FSS) shows several advantages of flat passband, high selectivity etc. over a conventional FSS. However, the existing full-mode SIW-based FSS has a low oblique incidence stability due to a large element spacing. In this paper, a quarter-mode SIW (QMSIW) cavity has been used to design a wide-angle FSS. The proposed FSS remains stable under a 60° incidence while the element size is reduced by over 60% compared to that of the full-mode SIW-based FSS. Thanks to the QMSIW cavity, a square loop slot has been added around the miniaturized cavity in this work to simultaneously achieve wideband and wide-angle characteristics.