Near-subsurface imaging in an absorbing embedding medium with a multistatic/single frequency scanner
Résumé
Probing the near-subsurface in the presence of absorbing media is a very challenging problem. Within that framework, we analyse the capabilities of a mono-frequency/multistatic set-up for detecting shallowly buried targets. As the antennas constitute an important part of the probing device, an accurate method for modelling the antennas behaviour is proposed. This modelling, performed thanks to a correct balanced set of elementary sources, is then incorporated in the calculation of the scattered field, performed with a home-made Finite Element Method software. Efforts have also been put into the measurement procedure. The measured fields are thus post-processed with an efficient method which takes profit of the spectral bandwidth properties of the scattered field. These fields serve as input data for the inversion algorithm, an extension of the DORT method to elongated targets. This qualitative and fast imaging procedure, which exploits the spectral properties of the multistatic scattering matrix, has been adapted to the present stratified configuration. Imaging results of shallowly buried targets embedded in a high losses medium are presented to assess the well-behaviour of the proposed methodology.