基于方位向去斜的星载滑动聚束两步成像处理算法研究

两步成像算法通过方位向去斜处理可以有效地降低星载滑动聚束SAR原始回波的多普勒带宽。为了有效地防止频谱混叠，脉冲重复频率(PRF)需要大于方位向去斜后的残余多普勒带宽，这也是两步算法可以应用于滑动聚束SAR数据处理的前提。为此，论文首先在距离向频域和方位向时域内详细地推导方位向去斜处理后残余多普勒带宽的解析表达式，得出残余多普勒带宽与距离向带宽、波束方位向宽度和波束方位向转角有关；然后在距离向时域和方位向时域内通过分析距离徙动引入了距离向信号对方位向信号的幅度加窗效应，定性地分析和验证频域内推导的残余多普勒带宽方程的正确性。最后，通过计算机仿真验证了文中理论分析的正确性。

Study on Two-step Imaging Based on Azimuthal Dechirp in Space-borne Sliding Spotlight SAR

Based on dechirp processing,the two step imaging can effectively decrease the Doppler bandwidth of the echo in space borne sliding spotlight SAR.In order to overcome the alias of the echo,pulse repeation frequency(PRF) should be larger than the residual Doppler bandwidth of the dechirped azimuth signal,which is the fundamental of the two step imaging algorithm.Firstly,the formula of the residual Doppler band-width(RDB) of dechirped azimuth signal in the range frequency and azimuth time domains,which was related to the transmitted bandwidth,azimuth beam width and the azimuth rotation angle,was derived.Secondly,the influence of the window function of the dechirped azimuth signal in two dimensional time domains was analyzed by introducing range migration,and the derived RDB formula was analyzed and validated.Finally,the simulation results validate the analysis.