W-Band $8\times 8$ Slot Array Antenna Using Hybrid Processing Technology of Silicon Micromachining and Metal Machining

In this paper, a multilayer W-band
$8\times 8$
slot array antenna processed using hybrid technology of silicon micromachining and metal machining is presented. The proposed antenna is composed of four silicon layers for radiating part and two metal layers for feeding network. Adjacent gold-plated silicon substrates and the metal cover plate are connected by gold-gold bonding. Using bulk silicon processing, high fabrication accuracy is realized for the 94-GHz large-scale array antenna. Metal-machining gap waveguide with artificial magnetic conductor (AMC) structure is elaborated for the corporate feeding network. Each
$2\times 2$
-elements slots subarray is excited by the TM240-mode cavity element below. Besides, a structural transition from standard waveguide WR-10 to gap waveguide is employed. Simulated results indicate that the proposed antenna can achieve 6.4 %
$(\vert \mathrm{S}11\vert < -10\text{dB})$
operating bandwidth covering from 91.2 to 97.27 GHz, with the gain greater than 26.1 dBi. The proposed antenna has the merits of high gain, heterogeneous integration and low cost, promising usage in various millimeter-wave wireless systems.