Helicopter-borne measurements of radar backscatter from forests

Helicopter-borne scatterometer measurements of various forest and surface types were conducted in spring 1988 in Espoo, near Helsinki. The scatterometer operates at 5-4 and 98 GHz and employs four linear polarizations (VV, HH, VH and HV). At each of the eight channels the radar can measure the backscattering properties of a target with a range resolution of 1 metre. The experimental results indicate that the location of backscattering sources within the forest canopy varies substantially with tree species. By applying principal-component analysis to the radar return versus range spectrum, identification of tree species is shown to be possible.