Book Description

Since World War II there has been a tremendous development and expansion of telecommunication facilities in the frequency range above 100 mc. Particularly at these frequencies, the characteristics of the tmosphere and terrain affect the propagation of radio waves. The presence of the troposphere manifests itself in many ways. One of its more important chracteristics is the mechanism which causes more efficient radio wave propagation than can be accounted for by diffraction alone. There have been several different theories put forth to explain this phenomenon (all of which involve the troposphere, and in some instances the stratosphere as well) and the effect of the variations in atmospheric refractive index upon the propagation of electromagnetic waves. Layers and ducts, which are characterized by horizontally homogeneous discontinuities in the vertical gradient of refractive index, inffluence line-of-sight paths as well as non-line-of-sight paths. Regular fading as well as prolonged space-wave fadeouts are associated with these atmospheric conditions. (Author).