Electromagnetic imaging for non–intrusive evaluation in civil engineering

In this paper an imaging approach for non-intrusive evaluation. of civil structures is discussed. The approach is based on the inversion of scattering data measured in near field. Cylindrical geometries are considered under transverse magnetic (TM) illumination conditions. The integral relationships of the inverse scattering problem are discretized and solved by an Inexact-Newton method, which has been found to be very effective in solving ill-posed inverse problems. The approach takes into account the nonlinear nature of the electromagnetic inverse. scattering problem, since no approximations are applied (except the ones related to the discretization of the continuous model). After the inversion of the measured data, the imaging method provides images of the dielectric properties of the cross section of the civil structures under test. The mathematical formulation of the method is briefly discussed and the results of numerical simulations are reported. Simplified geometrical configurations are considered, but with dielectric properties close to those of real materials employed in the field of civil engineering.