近场散射体对阵列超分辨波达方向估计性能的影响和补偿方法

测定电波到达方向（DOA）是无线电定位系统的基本任务之一，先进的阵列超分辨测向技术获得广泛关注。在船载和机载等平台应用中，阵列天线由于受安装空间所限，其旁边存在散射体，这时阵列接收到的信号既包括远场目标信号又有近场散射体散射出多径信号。本文分析了这种近场散射信号对DOA估计性能的影响，即散射信号会在DOA谱上多形成一个干扰性质的谱峰，并且若散射信号来波方向靠近直达波来波方向时，会造成模糊现象。最后文章在多重信号分类算法（MUSIC）的基础上提出一种补偿方法，能够很好的抑制散射信号所造成的这种影响,实验仿真结果验证该算法的有效性。 

An approach for DOA estimation in the presence of near field scatterers

Direction of arrival (DOA) estimation of radio waves is one of the basic tasks in radio source location systems, where array super-resolution technologies are widely applied. In the ship-borne and airborne applications, there are many near-field scatterers nearby, due to the space limitations. Thus, the received signal includes both the desired components from the far-field sources and the coherent interferences from the near-field scatterers. This paper analyzed the effects of the near-field scattering on the DOA estimation. It is shown that the estimated angular spectrum could be dramatically degraded, even totally ruined by the near-field scattering. The spatial smoothing approach, a popular approach to handle coherent sources, was also shown to be inappropriate to the near-field scattering. This paper proposes a new approach that treats the near-field scatterers as a part of the receive antenna. The simulation results, using the Multiple Signal Classification (MUSIC) as an example algorithm of DOA estimation, illustrated that the new approach works perfectly in the presence of near-field scattering without other extra operations such as spatial smoothing.