Radar imaging of ships at sea

High resolution radars are able to resolve large objects into their constituent parts and thereby provide information on the sizes and types of targets in the field of view. The simplest high resolution technique is the use of a wide bandwidth transmission to provide high range resolution, which results in a one dimensional projection of the target. A second dimension may currently be provided by one of two techniques: synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR), both of which produce across range resolution. In this paper, a brief description is given of the imaging theory, followed by the limitations imposed by the use of approximate processing methods and the estimation of unknown motions. Finally, a schematic example is given of a hybrid SAR/ISAR image result, with a discussion of the processing required