Very high resolution microwave measurements of the scattering from vegetation

Results are presented from an indoor near-field monostatic microwave imaging system using VV polarisation capable of providing the 3D scattering characteristics of a target. The technique is first demonstrated with a collection of corner reflectors in a simple geometric arrangement. It is then used to provide a detailed 3D map of a more complex natural target, a small Colorado blue spruce tree (Picea pungens glauca). The measurement process collects data using vector network analyser techniques over a synthetic 2D aperture. Image reconstruction uses the plane-to-plane imaging algorithm. The images produced are at sufficiently high spatial resolution (~5 cm) that individual plant components are resolved, and the ability to select any volume pixel from within the target allows features in the microwave imagery to be readily associated with the physical attributes of the tree. Use of software manipulation to view successive planes passing through the tree as an interactive movie, from any chosen aspect, greatly enhances the observer´s appreciation of the dynamic nature of the target´s scattering behaviour