Reconstruction of separate scatterers by a multiscale approach to microwave imaging based on the electric field integral equation

Microwave imaging methods, i.e., approaches able to reconstruct the distributions of the dielectric characteristics of unknown objects starting from samples of the scattered electric field, are gaining a growing importance in the scientific scenario. Several new algorithms have been devised in the past few years. However, there are still open problems, mainly related to the computational complexity and to the ill-posedness of the problem. This paper describes a new approach based on a focusing technique, which is able to concentrate the inspections only to the subregions of the scene under test where scatterers (or defects inside an object) have been previously detected. In particular, the present contribution concentrates on the extension to the case of multiple separate scatterers. The electromagnetic inverse problem is formulated through integral equations and solved by means of an Inexact-Newton method. The capabilities of the approach in locating separate or multiple scatteres are evaluated by means of numerical simulations.