Three dimensional through-wall imaging: Inverse scattering problems with an inhomogeneous background medium

This paper investigates the three dimensional inverse scattering problem with an inhomogeneous background medium where the known inhomogeneities are bounded in a finite domain. The forward scattering problem is solved using the finite element-boundary integral method (FEM-BI) while the inverse problem is oriented to minimize a cost function using nonlinear conjugate gradient optimization algorithm. The background Green´s function at each discrete point on the surface of the computational domain can be numerically obtained using commercial software. Such an approach shrinks the domain of inversion to a much smaller region than the standard finite difference approach. The algorithm presented in this paper finds wide applications in nondestructive evaluation, such as through-wall imaging.