ABSTRACT
Synthetic aperture radar (SAR) spot mode is characterized by the antenna steering operation that illuminates, during all the acquisition time, the same area (limited in both range and azimuth directions) over the ground. The achieved azimuth resolution gain is traded off by loss of coverage derived by illumination of a limited area along the sensor flight path. Investigation of the spot signal characteristics is in order. Spectral characteristics of the spot signal are in order. Computation of the raw signal azimuthal bandwidth is in order. As already noted, the spot azimuth bandwidth is usually much larger than that of the strip case, thus resulting in improved resolution. Algorithms first developed for generation of spot images directly derive from, or can be related to, computer tomography techniques. The most popular spot focusing techniques based on tomographic approaches are briefly outlined. To save an unitary view on all mode processing, authors extend the theory of strip mode focusing to the spot one.
