The existing inverse synthetic aperture radar (ISAR) imaging methods for uniformly accelerative rotating targets usually estimate the rotation parameters via 2-D search, which leads to a huge computational load. A novel ISAR imaging method based on chirp-Fourier transform is proposed, which utilizes the characteristic of uniformly accelerative rotating target's echo phase that the ratio of the coefficient of the second order term of scattering point's echo phase to that of the first order term is only determined by target's rotation parameters. The estimate of the ratio can be obtained by searching the frequency modulation coefficient of chirp-Fourier transform that minimizes the entropy of target's cross-range profile, which is a 1-D search. Then the well-focused ISAR image can be obtained by taking corresponding chirp-Fourier transform on each range cell' s echo. Simulation results verify the validity of this method.%现有匀加速旋转目标逆合成孔径雷达(inverse synthetic aperture radar,ISAR)成像方法通常采用二维搜索估计目标转动参数,从而导致计算量大.提出一种基于调频傅里叶变换的ISAR成像方法.该方法利用目标散射点回波相位二次项系数与一次项系数的比值仅取决于目标转动参数这一特点,通过搜索调频傅里叶变换的调频系数使目标横向像熵值最小,得到该比值的估计结果,避免了二维搜索导致的计算量大的问题.然后对备距离单元回波作相应的调频傅里叶变换,即可得到聚焦良好的ISAR像.仿真结果验证了该方法的有效性.
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