机载混合模式SAR波束指向控制对图像质量的影响

Effect of Air Hybrid Mode SAR Beam Point Steering on the Image Quality

针对机载混合模式SAR系统,该文给出了步进式波束控制下雷达波束对地面点目标照射强度的数学模型;通过分析方位向回波压缩信号,结合数学推导,提出波束控制对图像质量的影响主要体现在:波束指向被控时间导致出现无穷多对成对回波;混合度造成的主瓣展宽导致方位向分辨率下降;混合度造成的旁瓣压低导致成对回波对图像质量影响加大;混合度和波束指向被控时间相互作用使成对回波存在畸变。并利用计算机仿真验证了论证分析的正确性。最后对机载混合模式SAR波控方案的制定提出了建议。

A mathematical model of the illumination intensity, which is imposed on the point target by the radar beam step steered, is proposed for the hybrid mode SAR system. By the analysis of azimuth compressed echo signal combining mathematical deduction, the effects of beam pointing on the image quality are proposed, which are including： the steering time of beam pointing causes infinite paired echo; the hybrid factor causes the extension of the main lobe, which results in the decrease of azimuth resolution; the hybrid factor causes the decrease of the side lobe, which increases the effect of paired echo on the image quality; the interaction of the hybrid factor and the steering time of beam pointing causes aberration of echo. These are also demonstrated by the simulation. Finally, the suggestion of establishment of the hybrid mode SAR antenna beam point steering is proposed.