一种基于谱分析与改进方位非线性变标的大斜视聚束成像算法

针对大斜视聚束SAR成像中方位频谱混叠，且距离向与方位向严重耦合的问题，该文提出一种利用谱分析(SPECtral ANalysis, SPECAN)解方位频谱混叠、距离向采用调频变标(Chirp Scaling, CS)、方位向采用改进非线性变标(Extended Non-linear Chirp Scaling, ENCS)的大斜视聚束成像算法，首先将回波信号走动校正，然后利用SPECAN消除方位频谱混叠。进行距离徙动校正(Range Cell Migration Correction, RCMC)之后，利用CS消除距离弯曲的空变性，方位向采用ENCS补偿沿方位向变化的多普勒调频率，从而有效地提高了方位向的聚焦深度。仿真结果和分析表明，该方法能够在较大斜视角的聚束SAR模式下得到聚焦良好的高分辨率场景。

A Highly Squinted-spotlight Imaging Algorithm Based on Spectral Analysis and Extended Non-linear Chirp Scaling

Due to the problem of azimuth spectral folding and large migration and strong range dependence on the second range compression for high-squinted spotlight. This paper proposes a method combining the advantages of SPECtral ANalysis (SPECAN) with Extended Non-linear Chirp Scaling (ENCS). First, after Range Cell Migration Correction (RCMC), azimuth spectral folding problem is removed by SPECAN. The variation of quadratic range cell migration correction is removed by chirp scaling. The chirp rates of scatterers in the same range gate are dependent on the azimuth position because of RCMC. So, the extended nonlinear chirp scaling is used to solve the problem of chirp rate dependent on azimuth position. Then focused scope of azimuth is extended. Simulation results verify that this method can get good quality image for high resolution in high squinted spotlight mode.