Abstract: An improved method and apparatus for microwave imaging of an inhomogeneous target, in particular of biological tissue, compensates for the interactions between active antennae and nonactive antennae. Measured electric field data are processed in magnitude and phase form so that unwrapped phase information may be used directly in the image reconstruction. Initial finite element measurements and calculations are used to determine the perimeter dimensions of the target being examined, resulting in more accurate image reconstructions. An improved regularization technique is a hybrid of a Marquardt regularization scheme with a spatial filtering technique and a Tikhonov regularization scheme. An improved switching matrix enables simultaneous sampling of electric field data from a plurality of receiving antennae.

Abstract: The invention provides apparatus and methods for determining electric field properties of an inhomogeneous target. The electric property distribution on a coarse mesh discretization of the target is first estimated; and then the electric field on a fine mesh discretization of the target is computed. The fine mesh has finer discretization than the coarse mesh and is overlapping with the coarse mesh. The electric field is then measured at preselected measurement sites within a homogeneous region external to the target. A Jacobian matrix is also calculated which represents a sensitivity calculation relative to a change in the electric field at selected measurement sites due to a perturbation in the electric property distribution on the coarse mesh. A difference vector is formed between the computed electric field and the measured electric field, and an update vector is added to the electrical property distribution as a function of the difference vector and the Jacobian matrix.