Radar return from a continuous vegetation canopy

The radar backscatter coefficient
\sigma\deg
of alfalfa was investigated as a function of both radar parameters and the physical characteristics of the alfalfa canopy. Measurements were acquired with an 8-18 GHz FM-CW mobile radar over an angular range of
0\deg-70\deg
as measured from nadir. The experimental data indicate that the excursions of
\sigma\deg
at nadir cover a range of nearly 18 dB during one complete growing cycle. An empirical model for
\sigma\deg
was developed, which accounts for its variability in terms of soil moisture, plant moisture, and plant height.