Synthetic-aperture radar imaging

Synthetic-aperture radar (SAR) has become an important tool for remote sensing of the environment. However, until recently SAR systems, particularly airborne ones, have been incapable of yielding focused undistorted imagery consistently. Before any meaningful image understanding can be attempted it is essential to define the imaging function under all operating conditions. Some imaging problems are totally predictable and can be corrected in principle. The most serious difficulties are associated with unknown variations in the aircraft dynamics. In this review the author outlines the physical principles underlying SAR imaging, including a self-consistent scheme for the production of near-perfect images based on motion compensation from inertial navigation systems and a data-dependent autofocus and phase-correction technique.