Identification of Primary Contributors to the Backscatter from Pine, Pin Oak, Black Walnut, American Sycamore, Sugar Maple and Creeping Juniper at 10 GHz

A short-range very-fine-resolution FM-CW radar scatterometer has been used to identify the primary contributors to 10-GHz radar backscatter from six different species of trees. This system had a range resolution of 11 cm with a 16-cm-diameter illumination area at the target range of 4 m. Constituent defoliation was applied to each target. For pine trees, the strongest backscatter and strongest attenuation in the radar signal were caused by the needles. Cones, although insignificant contributors to the total backscatter, were more important for backscattering than for attenuation. For pin oak, black walnut, American sycamore, and sugar maple trees, leaves were the strongest cause of backscattering and attenuation. For pin oak and American sycamore trees, the petioles showed relatively strong backscattering properties in the absence of the leaves. As the leaves were removed, small twigs and branches also showed relatively strong backscattering properties while the fruits proved to be insignificant elements