Numerical Linear Algebra for Nonlinear Microwave Imaging

A nonlinear inverse scattering problem arising in microwave imaging is analyzed and numerically solved. In particular, the dielectricproperties of an inhomogeneous object (i.e., the image to restore) are retrievedbymeans of its scatteredmicrowave electromagneticfield (i.e., the input data) in a tomographic arrangement. From a theoretical point of view, the model gives rise to a nonlinear integral equation, which is solved by a deterministic and regularizing inexact Gauss-Newton method. At any step of the method, matrix strategies of numerical linear algebra are considered in order to reduce the computational (time and memory) load for solving the obtained large and structured linear systems. These strategies involve block decompositions, splittingand regularization, and superresolution techniques. Some numerical results are given, where the proposed algorithm is applied to recover high resolution images of the scatterers.