Improved Microwave Scattering Model for a Soybean Canopy

A soybean canopy can be modeled as a layer of discrete scatterers with prescribed orientation statistics over a dielectric half-space. The discrete scatterers can be approximated by canonical geometries, such as thin dielectric discs and cylinders used to represent leaves, stems and fruit, respectively, and the scattering amplitudes computed using analytical approximations. These can then be used to compute the total scattering coefficients from the canopy by using the Distorted Born Approximation (DBA). However, modeling of the fruit with a simple cylinder is not representative due to the fruit's complex geometry, dielectric constant inhomogeneities, and near-field coupling effects, due to fruit clustering. Commercially available electromagnetic field solver's, like Altair's FEKO can be used to accurately compute the scattering amplitude of the soybean fruit cluster. A comparison between the total scattering coefficients using the approximate and FEKO models with an experimental dataset shows that the FEKO model resulted in a closer match with the measurements.