Analytical determination of propagation paths near gyroharmonics

Abstract

The propagation of waves in a hot magnetoplasma near gyroharmonics is studied by means of analytical ray tracing. To get the parametric equations of the paths a dispersion relation is first obtained through the electrostatic hypothesis and some mathematical approximations. For this case, it is shown that, except near reflection, waves transmitted from an ionospheric sounder travel almost along the static magnetic field and that the gradient of the magnetic field may be responsible for their reflection back to the spacecraft antenna. In certain cases two distinct trajectories can simultaneously intersect the receiving antenna thus giving rise to beats which are sometimes observed experimentally. The theoretical formulas are applied to a 3 f H resonance.