L-Band Radar Scattering from Grass

A radar system based on an HP Network Analyzer has been developed to study the backscatter from vegetation. The antennas are mounted on a 'cherry picker' truck and the radar is operated at L-band for this experiment. Radar measurements of a grass field located at the USDA Agricultural Research Center in Beltsville Maryland, were made during the late fall of 1991. Three trihedral corner reflectors of different s izes were used to calibrate the radar. The radar returns from the grass were measured at three incidence angles. The ground truth and canopy parameters such as blade and stem dimensions, moisture contents of the grass and the soil, blade and stem density, etc. were also measured. These parameters are used in a distorted Born approximation model to compute the backscatter coefficients from the grass layer. The model results are compared with the radar data.