Simulating coherent backscattering from crops during the growing cycle

The backscattering coefficient and the position of interferometric phase center of wheat and sunflowers during the growing cycle have been computed by using a coherent electromagnetic model. In the model, the scattered fields are added coherently and the attenuation in the canopy is computed by means of Foldy\´s approximation. The comparison between model simulations and experimental data has shown that model results match reasonably well with the measured backscattering. As the plant grows, the backscattering of wheat ("narrow leaf" crop) decreases, whereas that of sunflowers ("broad leaf") increases. An analysis of the various terms that contribute to backscattering has indicated that the most significant contribution is given by the double scattering soil-stalk and that the position of the interferometric phase center is close to the soil. When the contribution of leaves is more significant, as in the case of sunflowers, the interferometric phase center goes up to about one quarter of the full plant height. This result demonstrates the potential of the interferometric observation in providing significant new information on crop classification algorithms based on scattering mechanisms