A new approach to the mode theory of VLF propagation

Abstract

An atte mp t is made in t his paper to present a concise derivation of t he mode t heory of VLF propagation. T akin g no te of t he fact that t he important modes for long-distance propagation are near grazing, sui table approximate forms of t he wave fun ctions m'e in tro-duced at t he outset, rather t ha n at t he end, of t he analysis. It is th us poss ible to acco un t for t he influence of eart h curvat ure in a re latively con cise manner. Thc ll1f1uence of t he eart h's magnetic fi eld is also disc ussed. Finally, llumerical res ults for t he attenuation and t he phase velocity of t he domin a nt mode are presented .