ABSTRACT
This chapter examines in some detail the key issues associated with the propagation of an electromagnetic wave through the Earth’s atmosphere. In order to appreciate the limitations and approximations inherent to existing treatments of radio wave propagation in the Earth’s atmosphere, it is necessary first to understand how electromagnetic waves interact with matter. The description of wave propagation in terms of the effects of the medium on the incident phase front and wave number forms the basis for the development of geometrical optics. The resulting analysis is applicable primarily to propagation through the Earth’s ionosphere at altitudes above 70 km where the plasma density is sufficiently high and scale lengths are sufficiently long to significantly affect the electromagnetic pulse. The physical processes inherent to the propagation of an electromagnetic wave through the Earth’s atmosphere depend strongly on the frequency content of the wave and on its power level.
