Redundant electromagnetic data for microwave imaging of three-dimensional dielectric objects

The possibilities of reconstructing the dielectric characteristics of unknown three-dimensional dielectric objects located inside a known volume are studied by means of numerical computer simulations. A numerical approach is proposed that is based on the moment method and on the utilization of redundant data (i.e., the values of the components of the scattered electric field measured outside the investigation volume) in order to strictly constrain the solution. In particular, a multi-illumination-angle multiview approach is proposed, which is based on an integrodifferential formulation of the three-dimensional inverse electromagnetic scattering problem. The analytical model is discretized using the moment method, and a regularization procedure is employed to find a solution, in a least-squares sense, to the resulting rectangular ill-conditioned linear system of algebraic equations. Since the heaviest computations can be performed off line, the computer resources required by the approach are entirely independent of the number of views. Numerical simulations have been performed to assess the effectiveness of the approach in dielectric reconstruction, in particular, by evaluating the distortions due to the ill-posedness of the inverse-scattering formulation