Improving the focusing properties of SAR processors for wide-band and wide-beam low frequency imaging

An increasing amount of interest has been evolved in VHF/UHF SAR applications. These radars have proven to be a very powerful method for underground and obscured object detection as well as for parameter retrieval purposes. For new upcoming applications, high-resolution VHF/UHF SAR imaging is an important task but cannot be achieved easily with conventional SAR processing techniques. A new algorithm is presented in this paper, which modifies the azimuth compression step of the extended chirp scaling (ECS) algorithm [Moreira et al. 1996]. It provides high azimuth resolution also for high squint or wide swath Additionally, the effect of strong motion errors in wide-beam azimuth processing is analysed and discussed, using simulated data as well as data collected by the airborne experimental SAR system of DLR (E-SAR) in P-band. In this context, a sub-aperture approach for motion error compensation in wide-beam azimuth processing is also presented