Abstracts:A single-layer, full metal, wideband, and high-efficiency slot array antenna operating in V band [(50 to 75) GHz] is proposed using a single corporate-feeding network based on gap waveguide (GW) technology. Compared with conventional multilayered slot array antenna, the proposed antenna utilizes only one waveguide feeding layer to excite the radiation slots; therefore, the assembly complexity of multilayer waveguide and manufacturing cost is greatly decreased. The proposed 16 × 16 slot array antenna consists of four 64-element smaller array antennas in which all radiation slots are fed by an E-plane groove gap waveguide (EGGW). Power division in each of the 8 × 8 element array antenna is realized by a wideband combined ridge and EGGW power divider. Two wideband E-plane groove gap waveguide T-junctions have been used to connect all four 64-element subarray antennas with proper phase and equal amplitude together to obtain higher gain. The final 16 × 16 slot array antenna has a peak gain of 32 dBi gain and about 36% impedance bandwidth at V band. Also, the full metal antenna array has an average efficiency of 80% over the entire bandwidth of 50 GHz to 72 GHz.