A Cavity-Backed Antenna Using SISL Technology for 77 GHz Band Application

A cavity-backed antenna based on substrate-integrated suspended line (SISL) technology is proposed for 77 GHz applications. The antenna is designed to be self-packaged using six substrate layers with embedded air cavities. Two rows of metal holes surround the core circuit to form the cavity and reduce the leaked field loss. Patches are printed in G5 and G6 layer and connected by metalized holes to form the double-side SISL with part of the substrate excavation to reduce the substrate loss. Thus, the simulation efficiency of better than 93% is achieved. Because of the cavity structure, the standing wave resonant mode can be obtained and achieve broadside radiation. A predominantly TE
₇₁₀
aperture field is obtained by adjusting the sizes of the backing cavity. The measured result shows that the proposed antenna has a −10 dB bandwidth from 75.6 to 81 GHz, covering 77 GHz automotive radar band and the max gain is 14.4 dBi. Based on this antenna, we design a differential-fed antenna array with a max gain of 17.5 dBi at 79 GHz.