Improving SAR image of mine-type targets from restricted radar band data

This paper presents a method to improve the SAR image of mine-type targets from wideband radar data that contain spectral gaps. The key concept that is exploited here is the correct identification of where the radar energy gaps map into in the ground-plane spectral domain of a targetís SAR image as a function of the targetís coordinates (particularly, its depression angle) as well as the radar system parameters. Once this is established, we apply an iterative method to recover the missing data in the targetís spectral signature. This scheme is capable of not only suppressing the undesirable side-lobes but also recovering subtle coherent (phase) information in the targetís SAR signature. Results using data from a low-frequency ultra-wideband synthetic aperture radar (SAR) designed by Mirage System will be presented.