Subsurface Near-Field Microwave Holography

A new method of near-field electromagnetic holography of subsurface dielectric targets is developed and studied in experiments with the multifrequency microwave system. It is based on the solution of the near-field inverse scattering problem obtained by data of multifrequency measurements of the two-dimensional (2-D) scattered field distribution with the source-receiver system that is located above the surface of a medium with buried dielectric targets. The solution, obtained initially in the lateral k-space representation, can be used to derive tomograms of distributed inhomogeneities or to determine the geometric shape of solid targets with sharp boundaries for further visualization as holography images with a subwavelength resolution. Such a holography method is studied in detail, including the formation of scattered field and signal for various samples in various media, achievable resolution, and effects of multiple scattering.