An imaging system and method in which the system carries out the method which includes the steps of: (a) determining an incident field, (b) using the incident field and a volume integral equation (VIE) to determine a total field, (c) predicting voltage ratio measurement at a receiving antenna by using the volume integral equation (VIE), wherein the VIE includes a vector Green's function, (d) collecting voltage ratio measurements from one or more receiving antennas, and (e) comparing the predicted voltage ratio measurements to the collected voltage ratio measurements to determine one or more properties of the object being evaluated. An S-parameter based inverse scattering method using the vector Green's function and VIE as its core is also described.