Antenna synthetic aperture radar (ASAR) image formation

It is well known that antenna characteristics can be significantly influenced by platform effects. While the "forward" problem of characterizing antenna performance on highly complex platforms has been well studied, an equally important problem is the "inverse" algorithm of spatially pinpointing where on the platform the undesirable scattering is coming from based on the forward solutions. In this paper, we set out to develop such a diagnostic algorithm to process computed or measured antenna radiation data. Our approach is based on the inverse synthetic aperture radar (ISAR) concept. ISAR imaging is a standard technique used in the microwave radar community to map the locations of dominant scattering off a target based on multi-frequency, multi-aspect backscattered data. We will extend this concept to the antenna radiation problem. By collecting multi-frequency, multi-aspect radiation data from an antenna mounted on a complex platform, we will form an ASAR (i.e., antenna SAR) image of the platform that will allow us to pinpoint the location of the dominant secondary radiation off the platform. Contrary to the conventional ISAR imaging, a key complication of the ASAR imaging scenario is that the antenna is located in the near field of the platform.