Skip to Main Content
This article reports the initial application of the finite-difference time-domain (FDTD) method to model extremely low-frequency (ELF) propagation around the entire Earth. Periodic boundary conditions are used in conjunction with a variable-cell two-dimensional TM FDTD grid, which wraps around the complete Earth sphere. The model is verified by numerical studies of antipodal propagation and the Schumann resonance. This model may be significant because it points the way toward direct three-dimensional FDTD calculation of round-the-world ELF propagation, accounting for arbitrary horizontal as well as vertical geometrical and electrical inhomogeneities of the ionosphere, continents, and oceans.