Abstract: The conventional ambiguity calculation method of spaceborne SAR is based on range one-dimensional pattern and azimuth one-dimensional pattern, and the range ambiguity and azimuth ambiguity are analyzed independently. However, the azimuth ambiguity is based on range ambiguity signal, which is caused by image processing. In order to solve the problem that the estimated range ambiguity value in system design is inconsistent with the actual imaging effect and to restore the essence of azimuth ambiguity, a new method of ambiguity analysis and calculation for spaceborne SAR was proposed. Firstly, the causes of range and azimuth ambiguity and the relationship between them were analyzed. Then, the range conversion model between the arbitrary pointing angle of the pattern and the actual observation to the earth was established. At the same time, based on the twodimensional pattern, the calculation method and steps of the omnidirectional ambiguity were given. Finally, the simulation design was carried out and the results show that the omnidirectional ambiguity calculation method is more in line with the actual imaging effect, providing a reference for the subsequent high-resolution spaceborne SAR system design and ambiguity suppression. 

Key words: spaceborne SAR, range ambiguity, azimuth ambiguity, omnidirectional, two-dimensional pattern