High efficiency 2?2 cavity-backed slot sub-array for 60 GHz planar array antenna based on gap technology

This paper presents a two layer 2×2-slot element as a sub-array for 60 GHz planar array antenna based on gap waveguide technology. The proposed element consists of 2×2 slots in a gap waveguide cavity where the cavity is fed through a coupling slot from a ridge gap waveguide corporate-feed network in a lower layer. The 2×2-slot sub-array is numerically optimized in an infinite array environment. The designed sub-array shows the relative bandwidth of 11% with reflection coefficient better than ™13 dB over 58.2-65 GHz frequency band. A prototype of a 8×8-element slot array antenna is designed and fabricated in order to verify the simulations.