Frequency-Spatial Adaptive Digital Beamforming Technique for Range-Angle Decoupling With High-Resolution MIMO Radar

High-resolution multiple-input multiple-output (MIMO) radar has been extensively employed for imaging across a wide range of applications. However, when radar systems are designed with a wide modulation bandwidth and a large aperture, performance degradation caused by range-angle coupling (RAC) becomes a significant challenge. Such coupling severely reduces angular resolution at off-boresight angles when conventional digital beamforming is utilized. To address this issue, a novel frequency-spatial adaptive digital beamforming (FSADBF) technique is proposed, in which adaptive steering vectors are generated based on frequency-spatial phase of the intermediate frequency (IF) signals for accurate angle estimation. Through this approach, target range estimation is performed within each angular cell, thereby avoiding the degradation of resolution caused by RAC, where the target is distributed across a large number of angle cells, particularly at off-boresight angles. Simulations and experiments have been conducted to validate the proposed technique, which significantly improves the angular resolution of MIMO radar.