Mapping of Ground Layer Discontinuities Using A Multistatic Subsurface SAR

Mapping the electromagnetic permittivities and thicknesses of underground layers is a vital step for proper focusing and image formation in subsurface imaging radars. Compared to traditional ground penetrating radar (GPR) that samples the scattered field along straight lines, detailed spatial information can be obtained using the concept of a newly developed subsurface multistatic synthetic aperture radar (SAR). For such system the scattered field samples are acquired along arbitrary multistatic paths. In this paper, an inversion algorithm for mapping underground layers using a multistatic subsurface SAR system is proposed. The algorithm forms a forward scattering model (FM) for the underground layers based on image theory and the generalized reflection coefficient of the layers. Subsequently, the misfit between the FM and the radar response is minimized with stochastic hill-climbing (SHC) algorithm to achieve inversion. The algorithm is tested on several full-wave simulation scenarios under noisy conditions demonstrating its potential effectiveness for mapping underground layers.