60 GHz slot antenna array based on ridge gap waveguide technology enhanced with dielectric superstrate

A 2 × 2 planar slot antenna array is designed at 60 GHz. The slots are fed by a printed feeding network based on the ridge gap waveguide (RGW) technology. Such a feeding network requires the slots to be more than a full wavelength apart, which causes excitation of undesired grating lobes. In order to reduce the grating lobes level, a low-cost dielectric superstrate at a distance of half wavelength in the air above the slot antenna array is used. The presence of the superstrate acts as a planar lens that increases the slot array gain by 7 dB along the broadside direction as well as greatly reduces the grating lobes level. The single element and the array characteristics are provided.