Zero-bandwidth SAR (ZB-SAR) for sub-surface imaging

The goal of carrying out sub-surface imaging from space or aircraft has so far remained elusive. In response, a description is offered here of a novel new imaging technique. Zero-bandwidth SAR (ZB-SAR) promises to deliver a previously unachievable high-resolution sub-surface imaging capability from large stand-off distances applicable to airborne and spaceborne platforms. This is in sharp contrast to current techniques, where discrimination relies on close-proximity measurement of the scene, usually with a ground-based system using large bandwidths. The scheme for separation of surface and sub-surface features is based on their differing DInSAR phase histories. Whereas the latter experience phase delays in sympathy to variations in soil moisture, these are absent from the phase history of surface features. Because the technique works on phase it is essentially independent of distance, and so applicable to large stand-off distances applicable to aircraft and satellite platforms.