小孔径天波超视距雷达多径模糊污染消除及海杂波抑制

由于电离层的结构分层性及厚度的不均匀，在超视距探测中会出现多径模糊的现象，使同一个目标出现在多个距离单元上，造成目标识别的不准确。针对传统天波超视距雷达( OTHR)接收阵列不具备俯仰分辨能力的不足，利用小孔径OTHR在俯仰方向的分辨能力，将几何估计结果与测向结果相结合，在俯仰方向自适应波束形成，消除了多径模糊带来的影响。同时改进了基于奇异值分解( SVD)的海杂波抑制算法抑制海杂波，提高了目标信杂比以便于后续检测。仿真实验结果显示所提方法能够很好地消除多径模糊带来的影响，同时抑制了海杂波，信杂比提高了9 dB。

Multipath fuzzy contamination elimination and sea clutter suppression for small aperture sky-wave over-the-horizon radars

Multipath propagation,caused by the layered structure of ionosphere,makes one target appear in different range cells,which leads to an inaccurate result of target identification. The receiving array of con-ventional sky-wave over-the-horizon radar( OTHR) is uniform linear array which doesn’t have the resolu-tion capability of elevation direction while small aperture OTHR system has it,because of its uniform circu-lar receiving array. To solve the problem of multipath propagation,this paper proposes to make adaptive beamforming in elevation direction with the result of geometric estimation and spectrum estimation under small aperture system. Moreover,to develop signal-to-clutter ratio( SCR) of echo signal,it improves the o-cean clutter suppression algorithm that is based on singular value decomposition( SVD) . Theoretical analy-sis and simulation result prove the proposed algorithm can eliminate multipath effect efficiently and avoid false targets. Besides,the improved SVD suppression algorithm increases the quality of ocean clutter sup-pression.