Characteristics of Electromagnetic Scattering from Vegetation Models using Random Wire Structures with Applications to Land Imaging SAR Systems

Clouds of both random curly wires and randomly-oriented straight wires with good conductivity are used to construct random volume models to simulate structures found in vegetation areas on the ground surface like naturally cultivated plants involving grass, trees, primary crops and chaff clouds. A variety of such random volumes are then subjected to incident electromagnetic plane wave of specific polarization to study the properties of electromagnetic scattering from such natural objects existing on the earth surface. It is shown that the frequency dependence of the Radar Cross Section (RCS) of such random structures has maxima around the frequencies corresponding to the natural modes of the wire structures constituting the volumetric model. On the other hand, the frequency behaviour of the RCS of these random clouds exhibits sharp peaks or anti-peaks over very narrow intervals of the frequency due to the generation of internal resonant modes between the finite-length pairs of wires constituting the random clouds. It is shown that such maxima, sharp peaks and anti-peaks of frequency behaviour of the backscattered field are very important to extract useful information for construction of microwave images and, also, for the classification of the vegetation areas that appear in earth remote sensing Synthetic Aperture Radar (SAR) images taken for the ground surface. The polarization properties of the fully polarimetric backscattering coefficients collected by a land imaging SAR system are studied through electromagnetic simulation.