Validation of the backscattered frequency correlation function for the inversion of biophysical parameters from natural targets

The computation of the frequency correlation function (FCF) in wide-band measurements of the radar backscatter from complex distributed targets allows the estimation of parameters related to the structure and geometry of the targets, since the individual response of the single components has slight variations with frequency. The application of this technique to data acquired in a laboratory under fully controlled conditions is described. The FCF of the distributed target has clear trends and features, as the main lobe width and the position and level of the secondary lobes, which can be used to characterize and classify it. The targets used in this experimental validation include two samples of maize crops, a fir tree and a ficus plant. The height and density of the maize plants are parameters expected to be inverted, but an analytical or numerical method for this inversion has not been developed yet. The FCF could be also employed to identify different vegetation kinds, since it is sensitive to the plant structure