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针对星载SAR(Synthetic Aperture Radar)滑动聚束成像模式,结合空间几何模型沿距离向对混合度因子进行了分析及修正.在此基础上研究了单点目标及全场景的多普勒带宽,并通过数学推导验证了两步成像处理算法克服频域混叠的有效性.通过进一步深入研究指出了两步成像算法的局限性,即对脉冲重复频率的选择具有较高的要求,否则在方位向图像域造成混叠.针对两步成像算法的缺陷提出三步扩展成像处理算法,在方位向聚焦后通过选择合适的deramp因子完成方位向的重采样,克服了方位向图像域的混叠,并研究了第三步deramp操作对方位向时域展宽的影响.最后通过仿真验证了三步成像处理算法的优越性.
In this paper, we analyze and correct the mixing degree factor along the distance with the spatial geometry model based on the Synthetic Aperture Radar sliding-beam imaging mode, and on the basis of which we study the Doppler bandwidth of the single target and the full scene, And the mathematical derivation verifies the effectiveness of the two-step imaging algorithm in overcoming the aliasing in the frequency domain.Through the further study, the limitation of the two-step imaging algorithm is pointed out, that is, the selection of the pulse repetition frequency has higher requirements, otherwise, Which leads to aliasing to the image domain.Aiming at the defects of the two-step imaging algorithm, a three-step extended image processing algorithm is proposed, and the azimuth resampling is completed by selecting the appropriate deramp factor after azimuth focusing, And studied the effect of the deramp operation on the azimuth broadening in the third step.Finally, the superiority of the three-step imaging processing algorithm was verified by simulation.