调频连续波圆周合成孔径雷达（FMCW CSAR）波数域成像算法中大孔径成像会导致目标散射系数发生变化，从而不能聚焦成像。针对此问题，提出了子孔径FMCW CSAR快速圆卷积成像算法，并利用非均匀傅里叶变换代替插值以提高成像效率。同时分析了FMCW CSAR多普勒历程，对子孔径划分原则进行了理论推导，给出了满足子孔径选取的表达式，通过仿真分析验证该算法能够有效避免波数域算法与子孔径难以结合的问题，结果表明,在该孔径内能较好地成像，而超过该子孔径范围，难以实现良好的聚焦成像。

Due to the large aperture imaging of the Frequency Modulation Continuous Wave Circular Synthetic Aperture Radar (FMCW CSAR) wavenumber domain imaging algorithm, the target scattering coefficient changes, so that the imaging cannot be focused. To solve this problem, a sub-aperture FMCW CSAR fast circular convolution imaging algorithm is proposed, and non-uniform Fourier transform is used instead of interpolation to improve imaging efficiency.At the same time, the FMCW CSAR Doppler process is analyzed, and the principle of subaperture division is deduced theoretically. The expression of subaperture selection is given. The simulation analysis shows that the algorithm can effectively avoid the difficulty of combining the wavenumber domain algorithm with the subaperture. The results show that better imaging is possible within the aperture, and it is difficult to achieve good focus imaging beyond the sub-aperture range.