Radar return from a continuous vegetation canopy

Abstract

The radar backscatter coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sigma\deg</tex> 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0\deg-70\deg</tex> as measured from nadir. The experimental data indicate that the excursions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sigma\deg</tex> at nadir cover a range of nearly 18 dB during one complete growing cycle. An empirical model for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sigma\deg</tex> was developed, which accounts for its variability in terms of soil moisture, plant moisture, and plant height.