Geometrical considerations of spaceborne SAR surveys

In this paper, the conventional approximation of stationary locally range-dependent straight orbits for LEO spaceborne SAR surveys is analysed. This approximation breaks down in demanding scenarios, e.g., high-resolution, squinted, or bistatic SAR, which are likely to play an important role in future spaceborne SAR missions. The dependencies of the image formation parameters with respect to topography and squint are analysed. Further, an exemplary analysis of the expected variations along the orbit, i.e., azimuth variance, is presented. To complete the analysis, the impact of the intrapulse motion of the satellite in squinted geometries is considered. The understanding of the residual geometric components including the parameters having an impact on them is a first step to the development of efficient SAR image formation schemes for future challenging spaceborne SAR missions.