Three-dimensional dielectric imaging by microwave inverse scattering with resolution unlimited by wavelength

An inverse scattering formulation for retrieving three-dimensional profiles of dielectric permittivity is presented. It yields quantitative dielectric images of a target, with resolution limited only by signal-to-noise ratio, and not by wavelength or diffraction. To overcome the wavelength limitation, scattering data in the near zone are utilized, and a method of least-mean-square and singular value decomposition is used to stabilize the matrix inversion. Results from computer simulation with an electrostatic model are shown to provide good images. As the electrostatic field is equivalent to an electrodynamic field with infinite wavelength, it illustrates the possibility of imaging by inverse scattering with resolution unlimited by wavelength