The Inverse Synthetic Aperture Radar or ISAR works similarly to a traditional Synthetic Aperture Radar or SAR except the relative motion between the antenna and the target is generally granted by the target rotational motion itself rather than the antenna translational motion.
Rotating –or apparently rotating- targets generate different Doppler shifts at different radii, which results makes the radar capable of generating a “convincing” target image in the range-Doppler plane.
By analysing such image, whose hotspots convey a lot of information on the target itself, various clues useful for target classification can be extracted. Air and sea target can be scanned and identified by comparison with a large target database using algorithms purposely developed in the framework of a cooperation with Selex Galileo, Nerviano site, Milan. The figure below schematically illustrates the feature extraction from the image of an aircraft in the range-Doppler plane.
These research activities are sponsored by the Radar Group at Selex-Galileo in Nerviano, Milan, Italy