基于改进wk算法的弹载SAR斜视成像

Squint imaging of missile-borne SAR based on improved wk algorithm

为提高弹载导引头成像精度,研究分析大斜视成像具有重大意义。针对传统wk算法在构造Stolt映射关系时未考虑等效速度变化以及进行方位校正时运算复杂等问题,提出基于改进wk算法的弹载合成孔径雷达斜视成像模型。首先,详细推导基于Stolt插值的wk算法,辨析在成像参数、多普勒中心校正和统一相位补偿等三个环节中易存在的混淆,为算法改进提供严谨模型。然后,针对非参考点目标的等效速度随着距离向不断变化,构造新的Stolt映射关系减小残余相位误差。在此基础上,针对较难精确实现多个点目标的方位位置校正函数,通过引入参考目标点构造近似校正函数,避免进行复杂的二维插值或坐标转换。最后,以大斜视成像为例,对多个点目标进行仿真,验证该算法的有效性。

In order to improve the imaging accuracy of the missile-borne synthetic aperture radar based on circular scanning,it is of great significance to study and analyze the large squint imaging.Aiming at the problem that traditional wkalgorithm fails to take into account the change of equivalent velocity and the complexity of operation in carrying out azimuth correction when constructing Stoltmapping relation,an improved wkalgorithm for missile-borne SAR slant imaging model is proposed.First,wkalgorithm based on Stoltinterpolation is deduced in detail to identify the potential confusion in three links,namely,imaging parameters,correction of Doppler center and unified phase compensation,so as to provide a rigorous model for algorithm improvement.Then,a new Stoltmapping relation is constructed to reduce the residual phase error as the equivalent velocity of the non-reference point target changes with the distance.On this basis,in order to avoid complex 2-D interpolation or coordinate transformation,a reference target point is introduced to construct an approximate correction function.Finally,the effectiveness of the algorithm is verified by the simulation of multiple point targets with large squint imaging as an example.