Variations in Omega Propagation Parameters.

Abstract : The dependence of first-mode propagation parameters on ground conductivity and the terrestrial magnetic field is investigated for frequencies within the spectrum of the Omega Navigation System, 10.2-13.6 kHz. The parameters are shown to exhibit gradual, monotonic variation with conductivity throughout the range of normal ground conductivities, and to present no special problem for propagation predictions. For very low conductivity ground, however, modal parameters show a complicated dependence on conductivity, and accurate predictions of propagation over permafrost and ice may therefore be difficult. (Author)