Mutual-coupling reduction of four-element cavitybacked slot antenna system using mushroom walls

In this paper, double-layer mushroom walls are applied in between the substrate integrated waveguide (SIW) cavity-backed slot (CBS) antennas for reducing inter-element mutual coupling of a four-element antenna system. The mushroom wall comprises two printed circuit boards (PCB), two arrays of metallic patches printed onto the both surfaces of the PCBs, a shared ground sandwiched in between the PCBs and an array of vias connecting the patches to the ground. A compact mushroom wall loaded four-element SIW CBS antenna array, wherein the center-to-center distance of the antenna elements is 0.42 λ (λ is the wavelength in free space at 2.4 GHz), achieves extremely high inter-element isolation of 43 dB throughout the -10 dB reflection coefficient bandwidth of 2.395- 2.433 GHz.