Propagation aspects
At low elevation angles, the propagation of radio waves is degraded by both atmospheric effects and scattering by the terrain. For many general-purpose surveillance requirements, the four-thirds earth approximation is a sufficiently good correction for atmospheric refraction (the strongest effect) and the other problems are ignored. When precision target tracking is required, all atmospheric effects have to be considered, and appropriate corrections made, based on local climatic information. The electron content of the ionosphere also causes attenuation and refraction effects, and a rotation of the plane of polarization. Radio waves passing through the ionosphere may suffer a form of scintillation that can affect space-borne earth-imaging radars.
Propagation aspects, Page 1 of 2
< Previous page Next page > /docserver/preview/fulltext/books/ra/sbra034e/SBRA034E_ch8-1.gif /docserver/preview/fulltext/books/ra/sbra034e/SBRA034E_ch8-2.gif