Enhanced angular resolution from multiply scattered waves

Multiply scattered waves are often neglected in imaging methods; largely because of the inability of popular algorithms to deal with the associated nonlinear models. This paper shows that by incorporating a known environment into the background model, we can retain both the benefits of imaging techniques based on linear models, as well as obtaining different views of the target scatterer. The net result is an enhanced angular resolution of the target to be imaged. We carry out our analysis in the context of Synthetic Aperture Radar (SAR) imaging, which is used to produce an image of a region on the earth’s surface (the target scatterers being buildings, etc). A plane or satellite carrying an antenna moves along a flight track, emitting pulses of electromagnetic radiation, which scatter off the ground, and the scattered radio waves are detected with the same antenna. The received signals are then used to produce an image of the terrain. We consider the case where the target we want to image is situated in the vicinity of an a-priori known reflecting wall. This is one of the simplest possible environments for the scatterer, and we will illustrate the enhanced angular resolution in this situation. Although we carry out our analysis here in the context of SAR, our technique is a general enough that it can be adapted to many imaging modalities, such as acoustics, ultrasound, elasticity, etc. The extension of the method to other more complicated environments is also possible.