A hybrid experimental/theoretical scattering model for dense random media

The subject of scattering of electromagnetic waves by dense media has been one of intense interest in recent years. The present paper describes polarimetric backscatter measurements made at Ku-band on layers of a dense medium under very carefully controlled circumstances. The experiments have a dual purpose: 1) to evaluate the degree to which the experimental observations are predicted by theoretical, particle-based, random media models and 2) to test a proposed hybrid model by which the scattering and extinction properties of a dense medium are characterized experimentally, allowing future modeling of the polarimetric response for any arbitrary configuration of the medium. The hybrid model assumes that first-order vector radiative transfer (RT) is a suitable theoretical structure, providing that the extinction and phase matrix components are appropriately specified; the specification is accomplished through an inversion algorithm involving polarimetric backscatter measurements. The major conclusions of the study are the following: 1) hybrid model is an adequate description of the dense medium scattering behavior; 2) conventional RT appears to give a reasonable estimate of the observed radar response, but dense medium RT gives a very low estimate; 3) phase function of the effective volume scattering element of the medium, obtained via the hybrid model, suggests a larger effective scatterer than the physical ones.