Design criteria and comparison between conventional and subaperture SAR processing in airborne systems

This paper compares two different approaches for designing airborne SAR systems. The first one is the most common where conventional processing is employed, and therefore wide antenna beams are to be used in order to avoid ambiguities in the final image due to attitude variations. A second approach is proposed to lower the requirements such system imposes based on subaperture processing. The idea is to follow the azimuth variations of the Doppler centroid, without increasing the hardware requirements of the system. As it is shown in this paper, this processing procedure must be complemented with precise radiometric corrections, because the platform may experience small attitude variations, which could increase/decrease the target observation time, inducing a significant azimuth modulation in the final image. This leads to the definition of a new criterion concerning maximum attitude deviations for an airborne platform.