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Abstract
The paper summarizes results of original researches on microwave remote sensing of vegetation conducted at the Institute of Radioengineering and Electronics of the AS, USSR during the last years. Vegetation models as continuous and discrete media are analyzed. The discrete approach appears to be more adequate for the description of microwave propagation in vegetation. Microwave scattering and absorption by plant elements of different shapes and sizes are studied. It allows one to obtain the relation between electrodynamic and biometric parameters of vegetation canopies. It is shown that microwave attenuation for given wavelength and vegetation type is defined by the canopy water content per unit area, the relative volume density of vegetation and the moisture of plant elements. The radiation model of vegetation canopy is proposed as a closed system of equations for the emissivity and the backscattering coefficient. Experiments measuring attenuation and emission properties of vegetation were perfomed under laboratory conditions as well under natural conditions with moving platforms and aircrafts. The developed models are in a good agreement with experimental data.