基于星载混合相控阵MIMOSAR的多方向测绘带成像及二维DBF处理

Multi-direction swath imaging and two-dimensional digital beamforming based on space-born hybrid phased-MIMO SAR

为解决图像模糊和图像混叠的问题,提出了将混合相控阵MIMO雷达与SAR相结合(混合相控阵MIMO SAR)的多方向测绘带成像方法,且提出二维数字波束合成(DBF)处理技术以实现无模糊宽测绘带高分辨率成像。首先建立该方法信号模型,推导了混合相控阵MIMO SAR的实际控制矩阵。然后针对多方向成像易造成图像混叠和距离模糊的不足,提出俯仰向自适应DBF算法,实现了图像混叠部分的有效分离且对模糊有很好的抑制。最后利用方位向加权对带外模糊置零。仿真结果表明该二维DBF处理技术的有效性。与星载双向和相控阵多向成像方法相比,该方法工作方式更灵活,能够满足多功能星载SAR的要求。

An imaging method of multi-direction swath based on space-born hybrid phased-MIMO SAR is proposed,which combines traditional phased-array radar with a new technique for multiple-input multiple-output（MIMO）radar,and the 2-D DBF for this system is presented to achieve unambiguous wide swath imaging with high azimuth resolution.Firstly,the signal model was built and the virtual control matrix of the Hybrid Phased-MIMO SAR was derived.Secondly,considering the image overlap and range ambiguity caused by multiple direction imaging,the adaptive Digital Beamforming（DBF）algorithm in range was proposed to separate the overlap area in images and to suppress the ambiguity.Finally,azimuth ambiguity that exceeds the signal bandwidth is suppressed by weighting in azimuth.Simulation results validate the effectiveness of this 2-D processing.Compared with space-born bi-direction SAR by two major lobes and multi-direction SAR by phased array,operation mode will be more flexible by using our method,and satisfy requests of multifunctional space-born SAR.