Low-Sidelobe Air-Filled Slot Array Fabricated Using Silicon Micromachining Technology for Millimeter-Wave Application

A low-sidelobe air-filled slot array is proposed and fabricated using silicon micromachining technology for millimeter-wave application. As is well known, the high-permittivity silicon prohibits the silicon-based antenna from having good performance. Here, this problem is addressed through manufacturing air-filled antenna on silicon substrate. An eight-way unequal power divider is adopted to excite eight air-filled slots and the excitation coefficients present a taper. At the end of the power divider, an air-filled substrate integrated waveguide cavity is used to improve antenna performance and suppress wave leakage, and eight silicon cuboids are stretched into the cavity beneath each slot to acquire good impedance matching. The input interface is selected as the ground-signal-ground structure to facilitate antenna-in-package solution that requires the integration of the antenna and chips or integrated circuits. The three-layered antenna is fabricated using through-wafer etching, gold-plating, optical alignment, and wafer bonding processes. The measured -10 dB impedance bandwidth is 1.27 GHz, and a measured fan-shaped beam at 58.5 GHz with a broadside gain of 11.95 dBi and a sidelobe level of 18.6 dB is obtained. The 3-dB beamwidth is about 14° in H-plane and 8-dB beamwidth is more than 175° in E-plane.