This chapter addresses SAR imaging based on processing the echoed data obtained from an airborne radar that does not spotlight a specific target area via beam steering. In this SAR system the radar maintains the same broadside radiation pattern throughout the data acquisition period on a fixed strip in the (slant) range domain. For such a data collection scheme, the illuminated cross-range area is varied from one pulse transmission to the next.
This form of SAR or inverse SAR (ISAR) database is mainly encountered in reconnaissance or surveillance problems. Such a SAR imaging system, which provides a map of a terrain within a fixed strip in the range domain, is also known as stripmap SAR or side-looking SAR.
The stripmap SAR form of target area radiation is analogous to a scenario in which someone is trying to view all objects in a dark room with a flashlight. With the flashlight in his right hand (the radar on the aircraft), that person would move his right arm to scan the room with the light of the flashlight. This preliminary phase of the search is to provide the individual with a general feel for what the room contains. In a similar way, stripmap SAR systems provide imaging information on the general condition and contents of, for example, a terrain area.
Consider again the individual with the flashlight in a dark room. Once he locates an object of interest after scanning the beam of the flashlight throughout the room, he might ...