64 $,\times,$ 64-Element and 32 $,\times,$ 32-Element Slot Array Antennas Using Double-Layer Hollow-W

This communication proposes high gain antennas having broad bandwidth characteristic for the 120 GHz band. The proposed antennas are fabricated by diffusion bonding of laminated thin copper plates which have the advantages of high precision and low loss characteristic even in a high frequency region such as the 120 GHz band. For stable fabrication using diffusion bonding, we propose a feeding structure which has a double layer. A 32 × 32-element array antenna shows more than a 38 dBi antenna gain with over 60% antenna efficiency and 15 GHz bandwidth (119.0-134.0 GHz) and a 64 × 64-element array shows a higher than 43 dBi antenna gain with over 50% antenna efficiency and 14.5 GHz bandwidth (118.5-133.0 GHz), respectively.