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 tropo¬sphere, the scattering eddies lie in the inertial range of statistical tur¬bulence 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 signifi¬cantly from that found with 'scattering blob' models.
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