稀疏阵列MIMO雷达低仰角目标测向方法研究

In the multipath and complex noise circumstance, the direction finding of low-grazing angle targets is difficult and challenging. Making full use of the diversity and virtual aperture expansion properties with sparse array MIMO radar, we can excavate its potential advantages in many aspects, such as high degrees of freedom, low mutual coupling ratio and flexible structure, which will be helpful for the efficient direction finding of low-grazing angle targets. To solve the multipath interference and noise errors with lower order moment, this project intends to study the signal model of low-grazing angle targets, the design and two-dimensional extension of sparse arrays, the sparse MIMO radar multi-parameter estimation with multipath effect and complex noises, and the parameter compensation for non-ideal sparse arrays. We focus on building a detection model of low-grazing angle targets and devising the perfect sparse MIMO configurations by optimizing the degrees of freedom and mutual coupling. Then, according to joint subspace-based method and compressive sensing theory, we study the efficient direction finding algorithm with suppressed multipath and complex noises, also including the optimized compensation theory of mutual coupling and gain-phase errors, which target at better performance, low complexity and high robustness. We finally form some innovative and useful conclusions for the direction finding of low-grazing angle targets, which can make positive contributions for the development of low altitude target detection.

多径效应和复杂噪声条件下的低仰角目标测向是具有挑战性的现实难题。充分利用稀疏阵列MIMO雷达的分集特性和虚拟孔径扩展特性，挖掘其高自由度、低互耦率、结构灵活等潜在优势，有利于实现高效的低仰角目标测向。针对多径相干及对消、噪声低阶矩高误差等现象，本项目拟开展低仰角目标建模分析、稀疏阵列结构优化拓展、稀疏阵列MIMO雷达多径和噪声条件下多参数估计、非理想稀疏阵列结构参数补偿四个方面研究。着力构建低仰角目标检测模型，设计自由度和互耦联合优化的稀疏阵列MIMO雷达结构，从子空间类算法与压缩感知理论的契合点出发，以优化估计性能、降低复杂度和提高稳健性为目标，研究能够抑制多径和复杂噪声的高效测向算法、优化互耦/幅相误差补偿理论，创新性地形成具有一定应用价值的低仰角目标测向理论和方法体系，为促进低空目标探测技术的发展提供理论依据和技术支撑。

低空目标探测是当前军事和民用领域亟待解决的难点问题，而低仰角目标测向又是其中关键性的瓶颈问题。本项目利用稀疏阵列MIMO雷达自由度高、互耦率低、结构灵活等优势，从低仰角目标回波信号建模分析、稀疏阵列结构优化设计、多径和非理想噪声条件下稀疏阵列MIMO雷达目标测向、幅相误差下稀疏阵列MIMO雷达目标测向四个方面进行研究：首先构建了多径与非理想噪声的参数模型，为后续研究奠定了理论基础。随后系统研究了稀疏阵列MIMO雷达优化设计理论，提出广义嵌套阵、互质面阵、嵌套子阵MIMO、高阶嵌套MIMO、互质子阵MIMO、二阶互质MIMO、对称互质MIMO和广义互质MIMO阵列等结构。接着基于灵活阵元间距稀疏阵，通过降复杂度两步CS算法提高了多径条件下稀疏阵列MIMO雷达的测向精度；基于对称互质MIMO雷达、嵌套MIMO雷达和2q阶嵌套MIMO雷达，研究了非均匀噪声、色噪声和非高斯噪声下的测向算法，提高了估计精度和稳健性。最后，通过增加辅助阵元、构造数据选择矩阵等方法提高了幅相误差条件下稀疏阵列MIMO雷达测向精度。.通过本项目研究，初步形成了稀疏阵列MIMO雷达低仰角目标测向理论和方法体系，研究成果对于解决低空目标探测定位问题具有重要的理论意义，对于构建严密可靠的防空体系和空管体系具有一定的参考价值。