前视阵列合成孔径雷达(SAR)成像可实现对前视盲区的二维分辨,在武器制导等军事领域极具应用价值。然而在特殊几何模型下,距离方位高度耦合且存在方位空变,这使得前视高分宽幅成像极具挑战。文中基于前视阵列SAR成像几何构型,推导了距离多普勒域的精确回波信号模型,通过解线性频调以及Keystone的方法实现距离方位二维解耦(RCM)校正。在此基础上,文中方法将目标多普勒频率在时间上进行一次以及二次分解,并通过重采样实现线性多普勒频率插值,消除每个距离单元中的方位空变残余相位误差,实现空变补偿。最后,通过方位聚焦以及波束形成获取了良好聚焦的前视阵列SAR无模糊图像,通过点目标以及面目标的仿真实验验证了所提方法能够有效实现前视阵列SAR解模糊成像。

Forward-looking array SAR imaging can achieve two-dimensional resolution of the forward-looking blind area, which is of great application value in military fields such as weapon guidance. However, under special geometric models, the high coupling of range-azimuth and the azimuth variation make high-resolution forward-looking imaging extremely challenging. The accurate echo signal model is derived in the range-Doppler domain based on the geometric configuration of forward-looking array SAR imaging. And the RCM correction with two-dimensional decoupling of range-azimuth is realized through the de-chirping and the Keystone method. On this basis, the target Doppler frequency is decomposed in time once and twice by the proposed method, and linear Doppler frequency interpolation is achieved through resampling. Azimuth residual phase errors in each range bin are eliminated to achieve spatial variation compensation. Finally, well-focused forward-looking array SAR images without ambiguity are obtained through azimuth focusing and beamforming. Simulations of point targets and surface targets verify that effective unambiguous forward-looking array SAR imaging can be achieved by the proposed method.

TN957. 52