多径条件下米波频分MIMO雷达波束性能及优化方法

Beam Performance and Optimization Method for Meter-wave Frequency Diverse MIMO Radar in Multipath Scenario

针对传统米波雷达低仰角下波瓣分裂和盲区问题,该文提出一种频率分集子孔径MIMO雷达,构建了该体制下多径特性定量分析的理论框架,推导了镜面反射和扰动多径模型及其联合发射-接收方向图增益闭合表达式;提出了多径抑制区概念及其边界条件,定义了描述低空波束覆盖性能的低可观测率定量评价指标;根据边界条件的解集优化了波束覆盖性能。理论分析和仿真结果表明由于充分利用了频率分集产生的距离依赖波束,该体制雷达相对传统MIMO相控阵雷达具有更优的低空波束覆盖性能,减小了米波雷达波瓣分裂和探测盲区。

Traditional meter-wave radar usually suffers from the problem of Beam Split （BS） and Radar Blind Area （RBA） in the situation of low-grazing angle. To alleviate this difficulty, a Frequency Diverse Subaperturing Multiple-Input Multiple-Output （FDS-MIMO） radar is proposed and a theoretical framework for the analytical investigation of multipath characteristics is presented. The specular and perturbational multipath model is built, along with closed-form expression of the joint transmit-receive beampattern gain. Moreover, a notional concept of Multipath Mitigation Area （MMA） is defined together with the corresponding boundary conditions, and the Low Observability Rate （LOR） is defined as a performance benchmarkan to evaluate the FDS-MIMO radar beam overage capability. Next, the FDS-MIMO radar low-altitude beam coverage performance is optimized according to the soutions of the boundary conditions. Both theoretical analysis and numerical results demonstrate the advantages of FDS-MIMO radar over the conventional phased-MIMO radar in terms of low altitude beam coverage performance, and the BS and RBA of meter-wave radar is decreased by ultilizing the range-dependent beampattern.