Mapping performance of curved-path SAR

Synthetic aperture radar (SAR) mapping is usually performed along a straight path. Curved paths away from the target area will increase the mapping rate significantly. Drawbacks are more complex signal processing and decreased azimuth resolution due to the reduced dwell time. In this paper, curved SAR mapping is analyzed in more detail, including squinted beam geometry. Relationships are derived how the SAR resolution and mapping rate are influenced by the curved SAR path. The nonlinear phase error, which defocuses the SAR image, is more accentuated than for straight-line SAR, in particular at squinted observation angles. Simulation examples show how the nonlinear phase error depends on side acceleration and mapping geometry after scene center motion compensation.