A Grating-Lobes Suppression Method for Wideband MIMO Millimeter-Wave Imaging Arrays
Wenrui Zhang, Wenyuan Shao, Yicai Ji, Guan Yang, Shiyou Wu, Chao Li, Guangyou Fang
Abstract
This article proposes a novel method for eliminating the first grating-lobe of wideband multiple-input multiple-output (MIMO) millimeter-wave imaging array. It exploits the position shift phenomenon of the first grating-lobe and can achieve grating-lobes suppression without additional calculation. The far-field formula for the first grating-lobe is derived, and the cause of its shift phenomenon in both azimuth and range directions is analyzed. The proposed multiapodization (MA) method can be used to cut off the part of the shifted grating-lobes while maintaining the resolution. However, nonsparse targets still have the far-field residual grating-lobes after MA. To solve the problem, the position formula and the detailed derivation of the residual grating-lobes are given. Therefore, a pixel search (PS) method can be used to remove them. The proposed MA can also be utilized to suppress the residual grating-lobes of the near-field MIMO array. Both simulated and experimental data in different system regimes and frequencies verify its effectiveness.