The Scattering of Radio Waves in the Atmosphere by the Turbulent Fluctuations in Refractive Index

摘要

Experiments have shown that high frequency radio waves can he propagated between distant points on the earth's surface by being scattered obliquely from irregularities in the atmosphere. The spatial variations of refractive index which are responsible for the scattering are present in both the troposphere and the ionosphere, although the physical origin of the variations is probably not the same at all levels. This note is concerned less with the quantitative explanation of the observed scattering in particular experiments than with the theoretical analysis of an assumed state of affairs, viz that the spatial variations in refractive index are the result of turbulent motion redistributing variations produced by some source. Thus the problem treated here is that of determining the characteristics of the scattered radio signal at a receiver R, given that monochromatic waves from a transmitter T are incident on a volume v (remote from £ and T) inside which the refractive index has a small random spatial variation due to the existence of turbulent motion.