Fading of Radio Waves Scattered by Dielectric Turbulence

Abstract

The fading of radio waves scattered by dielectric turbulence is shown to be the result of two effects. The first is time variation of the scattering eddies as seen in a coordinate system moving with the local wind velocity. The second is Doppler shifting produced by the convection of the scattering eddies by the mean wind and by the macro-eddies. In the troposphere, the scattering eddies lie in the inertial range of statistical turbulence theory. This makes it possible to find the envelope fading rate of the received scattered signal to within a constant of proportionality by using dimensionality and similarity arguments. The result is an expression for the fading rate as a function of carrier frequency which departs significantly from that found with ``scattering blob'' models.