Geometrical distortion correction for extremely high-squint parameter-adjusting synthetic aperture radar

The parameter-adjusting polar format algorithm (PFA) is demonstrated to be an effective imaging method for the high-squint synthetic aperture radar (SAR) in a previous study by the authors. However, while the previous work only focuses on the demonstration on the effectiveness of the parameter-adjusting PFA in removing the quadratic and higher order phases, the compensation to the linear phase, which determines the geometrical distortion, has not been discussed yet. Therefore, this paper presents a geometrical distortion correction (GDC) method for the extremely highsquint parameter-adjusting SAR. By deriving the linear phase error induced by the planar wavefront approximation, the positions of the focused scatterers are corrected via the cubic interpolation. The presented approach is verified by a simulated Ka-band airborne SAR in a geometry with an 85 degrees squint angle.