The interpretation of recently-measured propagation constants for audio-frequency electromagnetic waves in terms of model ionosphere profiles

Abstract

Results of a recent measurement by the author, at a period of minimum solar activity, of the phase velocity and attenuation of electromagnetic waves in the frequency range 40 c/s-10 kc/s are used, in conjunction with waveguide mode theory of propagation for the Earth-ionosphere duct, to derive theoretical daytime and night-time electron density profiles in the lower ionosphere. A perfectly conducting Earth is assumed, and a simple correction applied to take account of the vertical geomagnetic field. Good agreement is obtained between the experimental attenuation and phase velocity curves and those predicted for the ionosphere models. The daytime models show lower electron densities than a number of measured profiles, probably because of the low solar activity at the particular period of the observations.