Parameterization of VLF natural modes in a curved waveguide

Using an optimized computer program, exact earth equations for VLF natural modes are calculated for a waveguide with propagation along a great circle of the earth. The starting point is represented by a successively determined starting point table which is valid for ideal conducting walls and can be used to compute all relevant VLF modes with increasing phase velocity. The real electric and geophysical relationships are treated with impedance-similar boundary conditions in an iteration procedure. The characteristic propagation values, attenuation, amplitude, and phase relationship for arbitrary VLF paths are calculated with a minimum of computation time.