Cavity‐Backed SIW Slot Antennas at 60 GHz

In this chapter, we discuss some concepts, methodologies, and designs for substrate integrated waveguide (SIW) cavity‐backed slot antennas (CBSAs). Firstly, the operating principle of the cavity‐backed antenna is briefly described by dividing it into three parts, namely the excitation part, the cavity part, and the radiation part. The cavity part can be equivalent to an open‐ended resonant cavity supporting a two‐dimensional resonance on its cross section. Secondly, the cavity‐backed SIW slot antennas are analyzed from the feeding techniques, the SIW backing‐cavity, and the radiating slot, respectively. The feeding mechanism can be conveniently used by the microstrip line, grounded coplanar waveguide, SIW, and coaxial line. The size and resonant mode of the SIW backing‐cavity have significant impact on the antenna's performance. The SIW cavity, along with the half‐mode substrate integrated waveguide (HMSIW) cavity, and the quarter‐mode substrate integrated waveguide (QMSIW) cavity are discussed with the operating modes. According to different operating states, the radiating slots in the CBSA can be classified into resonant slot and non‐resonant slot. The common structures and shapes for the two kinds of slots are introduced in detail, and their working principle and design equations are presented for easy reference. Thirdly, some types of SIW CBSAs, including the wideband ones, the dual‐band ones, the dual‐polarized and circularly polarized ones, and the miniaturized ones, are reviewed form their design strategies, working mechanisms, and realized performances. Finally, an SIW CBSA is designed at 60 GHz as an example and the corresponding 2×4 arrays are implemented employing a single layer PCB process for mmW applications.