FDS-MIMO Radar Low-Altitude Beam Coverage Performance Analysis and Optimization

Detecting and tracking low-flying targets at low-grazing angles is a difficult task due to the possible beam split and radar blind area. To alleviate this issue, we propose a frequency diverse subaperturing multiple-input multiple-output (FDS-MIMO) radar with optimized low-altitude beam coverage performance. A specular echo model is first formulated in the presence of multipath propagation together with a closed-form expression for the joint transmit–receive beampattern. Then, a perturbational echo model is developed for anomalous terrain. Moreover, a notional multipath mitigation region concept is defined together with the corresponding boundary conditions. The FDS-MIMO radar beam coverage capability is evaluated by the low observability rate. Furthermore, the FDS-MIMO radar low-altitude beam coverage is improved according to the solutions of boundary conditions, and an adaptive frequency offset design strategy is proposed for the changing environment. Both theoretical analysis and numerical results demonstrate that the optimized FDS-MIMO radar outperforms conventional phased-array radar and MIMO radar in terms of low-altitude beam coverage performance.