Imaging under irregular terrain using RF tomography and numerical green functions

RF tomography has been proposed to localize and image man-made underground structures and tunnels using a set of arbitrarily distributed narrowband electromagnetic sensors placed above or below the ground. Basically, a set of s transmitters emit a monochromatic signal into the ground; waves impinge upon dielectric anomalies (e.g. tunnels) thus generating a scattered field. Finally, distributed receivers sample the scattered field and relay this information to a base station for post processing. For a deeper understanding of the principles of RF tomography for belowground imaging, see [1]. Currently, RF tomography is based upon the knowledge of the Green function of the scattering problem: analytic expressions are limited only to layered media with planar interfaces [5]. For irregular terrains, a numerical Green function has to be evaluated and here we show a proper reformulation of RF tomography that accounts for numerical Green function that describes the spatial impulse response of the terrain shape. This improvement lead to more reliable reconstructions compared to the case of a planar interface.