The effect of the Earth´s magnetic field on short-wave communication by the ionosphere

This paper is mainly a re-presentation of the magneto-ionic theory for oblique transmission through the ionosphere with special reference to numerical applications, but it is directed particularly to the problem of using ionospheric knowledge to plan short-wave long-distance communication. The quartic equation of the theory is solved graphically by the intersection of a straight line with a certain curve, and a chart is described for the construction of the latter for various values of the electronic density. By the method of stationary phase, simple expressions are obtained for the differential coefficients of the ray path, including the group time, lateral deviation and specific attenuation. Numerical integration along the ray path for a given density distribution is discussed with special reference to the relation of oblique to vertical transmission. Some preliminary results are given, but no detailed numerical survey is included, as this would more fittingly form the subject of a separate paper.