Extremely Low Frequency (ELF) Propagation Formulas for Dipole Sources Radiating in a Spherical Earth-Ionosphere Waveguide.

摘要

Extremely low frequency (ELF) propagation formulas are derived for dipole sources radiating in a spherical earth-ionosphere waveguide. In these formulas, the earth and ionosphere boundaries are modeled as scalar surface impedances. The spherical waveguide formulas are applied to predict the electromagnetic fields produced by vertical and horizontal electric dipoles (located on the surface of the earth) at antipodal ranges for several frequencies and propagation conditions. These results are used to establish the maximum ranges of validity of ELF propagation formulas that are based on the earth-flattening approximation. Numerous derivations are given in the appendices.