Communications Technology Handbook, 2nd Edition

27 Propagation

The propagation of electromagnetic waves through the space surrounding the earth depends upon many phenomena, some quantifiable according to a definite theory and some unpredictable except in a statistical manner. The nature of the earth’s surface in the immediate vicinity, the frequencies in use (see also Frequency bands in use, p. 143), the prevailing meteorological conditions, and many extra-terrestrial features all aid to make this line of research still very rewarding. Much knowledge of such propagation has thus been acquired by observation in a pragmatic way. The use of computers with modelling software now produces very acceptable sets of predictions from a given set of circumstances. Like antenna design, predictions about ...