94GHz fabrication of a slotted waveguide array antenna by diffusion bonding of laminated thin plates

We fabricate the single-layer slotted waveguide array antenna in 94 GHz band by diffusion bonding of laminated thin metal plates. This new fabrication technique is a promising one of low cost, because of the high-precision etching in low price. Perfect electric connection can be realized between the slotted plate and the grooved waveguide base by diffusion bonding even at a high frequency such as 94 GHz. A designed 18×18-element antenna is trial fabricated by using copper. The antenna efficiency is achieved at 60% for 31.4 dBi gain at 93.7 GHz in this copper antenna. The process of diffusion bonding using copper could result in over-etching of the slots by 50 um, which degrades the aperture efficiency by 0.8 dB.