Propagation characteristics in the earth-ionosphere waveguide for VLF waves emitted from trapping cones at high latitudes

摘要

It is important to clarify the relationship between VLF-ELF wave characteristics on the ground and in the ionosphere for a comprehensive understanding of the ground-based observation data. In this paper, the amplitude and polarization of VLF waves at various places on the ground are calculated with an ionospheric model at high latitudes, through a full wave technique when various size of trapping cones are existing. Some results of the numerical calculation are presented. Major results are as follows : (1) Waves with an amplitude within 12 dB of the maximum intensity are found in an area of 300km (east-west direction)×400km (north-south direction) when some part of the trapping cone overlaps with the transmission cone. (2) The left-handed polarization wave can exist even within a distance of 100km from the point of maximum intensity, where the intensity is as strong as ∿ -10dB of the maximum intensity.