相控阵雷达反演口径分布实现方位超分辨

Azimuth super-resolution for phased array radar by reconstructing aperture distribution

为了实现普通相控阵雷达的方位超分辨 ,需要知道天线阵面的幅相分布。通过对相控阵天线单元进行时序 Walsh- Hadamard相位权重可以反演该天线阵面的幅相分布。在此基础上再采用超分辨算法就可以得到目标的超分辨方位信息。所采用的超分辨算法是抗噪性和鲁棒性均较好的逐次逼近算法 [3 ]。为了得到平缓的相位分布 ,减少相位权重次数 ,对于不在正前方的目标采用了附加线性相位分布波阵面对准的方法。经数值仿真 ,对于一个 X波段、相控阵天线横向单元数为 1 39的雷达 ,在接收机输出信噪比为 1 5d B时 ,采用这种方法后方位分辨率的改善因子可达到 2 。

In order to realize the angle super resolution, both the amplitude and the phase distribution related to the incident waves should be obtained. The digital beam forming antenna array may be applied for this purpose. But it is quite costly. Alternatively the time sequence Walsh Hadamard phase weighting technique is proposed for the conventional phased array antenna. After measuring the outputs corresponding to the different weighting of this antenna, both the amplitude and the phase distributions may be reconstructed. Consequently, the angle super resolution may be achieved through the non linear spectral estimation. It chose RELAX algorithm [3] which possesses good performance under the low SNR. The equiphase surface of the array is shifted to face the targets. In so doingso, the phase distribution is smooth, consequently the number of phase weighting may be reduced. For an X band phased array antenna with 139 elements, by using this technique, the angle resolution is improved by a factor of 2 under the case of 15dB SNR. This technique can be applied in both radar systems and communication systems.