Extension of synthetic aperture radar imaging to nonlinear trajectories

Synthetic aperture radar (SAR) imaging is extended to nonlinear geometries using two new techniques: range relative Doppler processing (RRDP) and the invariant mapping technique (IMT). RRDP reduces range walk, which prevents the application of pulse Doppler radars or synthetic aperture imaging for most nonlinear geometries. IMT allows the transfer and accumulation of information from polygonal cells of arbitrary shape and orientation to a rectangular grid. Extended SAR imaging is illustrated by simulating reflectivity imaging for a millimeter-wave seeker on a downward trajectory