43dBi gain, 60% efficiency and 10% bandwidth hollow-waveguide slot array antenna in the 120GHz band

We propose high gain antennas with a broad bandwidth for the 120 GHz band. The proposed antennas are fabricated by diffusion bonding of laminated thin copper plates which has the advantages of high precision and low loss even in a high frequency region such as 120 GHz. For the stable fabrication using the diffusion bonding technique, we propose a new feeding structure with a double layer. A 32×32-element array shows 38 dBi gain with 70% antenna efficiency over 13 GHz bandwidth and a 64×64-element array shows 43 dBi gain with 60% antenna efficiency over 13 GHz bandwidth, respectively.