W-Band High-Efficiency Wideband Planar Array Antenna Based on MEMS Micromachining Technology

A W-band planar array antenna with high efficiency and wide impedance bandwidth using MEMS micromachining technology is designed and fabricated in this paper. The MEMS fabrication process of selectively etching and gold plating is employed to fabricate the precise structure with the similar property of the hollow waveguide. To satisfy the requirement of maximum thickness, the reduced-height waveguide is applied to design an H-plane equal-amplitude and in-phase power divider with the perturbed and septum structure to enhance its impedance bandwidth. A $\pmb{2}\times \pmb{2}$ -element sub-array is utilized to facilitate the layout of the feeding network in the lower layer. The wide-band-stepped horn is employed as the radiating element. Its simple configuration can guarantee good performance. Finally, an $\mathbf{8}\times \mathbf{8}$ array antenna is fabricated by the MEMS micromachining technology and measured. The total thickness is 2.65 mm, which is less than one free space wavelength. Measurement results indicate that the impedance bandwidth for $\vert \mathbf{S}_{11}\vert < -\mathbf{10}$ is 21.28%. The minimal gain can be up to 23.36 dBi within the whole operating frequency band. Total antenna efficiency is up to 75% covering the range from 86.5 GHz to 104 GHz.