The Transmission of Signals from a Horizontal Antenna

Abstract

IN the course of a mathematical investigation of the propagation round the earth of electromagnetic waves from a horizontal antenna, the result has emerged that, when the earth is regarded as a perfect conductor, the components of electric and magnetic force are zero both when the earth is regarded as surrounded by a conducting Heaviside layer and when no layer is present. Finite conductivity of the earth must thus be assumed in order to account for the propagation, and it is then found that the resulting forces are a small vertical electric force and a much larger horizontal magnetic one. The electric force is due to the ‘space waves,’ the magnetic force to the ‘surface waves’ described by Sommerfeld (Annalen der Physik, vol. 28 (1909), p. 665); the result of the analysis is in remarkable agreement with the conclusions he there expresses. The magnetic force may be analysed into perpendicular components, each of which consists of two simple harmonic oscillations differing in amplitude and phase, results of the same general type being obtained both with and without the Heaviside layer.