Microwave attenuation spectra of forest crowns

Super wide band waveguide transition system has been designed for measuring microwave attenuation by trees fragments in the frequency range 0.8-8.5 GHz. Field active measurements has been conducted that has provided data on attenuation by single trees in the frequency range 0.47...2.1 GHz. The data obtained has been compared with several data sets on attenuation properties of forests reported earlier. A simple formula has been proposed for microwave intensity extinction rate: γ=c f^β w, were γ is the extinction rate in dB/m, f is the frequency in GHz, w is the crown unit volume water content in kg/m³, c (in dB/kg/m²) and β (dimensionless) are the model coefficients that has been found from regression analysis of experimental data.