Topside ray trajectories near the upper hybrid resonance

Ray trajectories near the upper hybrid resonance show both similarities to and important differences with calculations near the resonance at the plasma frequency. As long as the upper hybrid frequency is less than the second harmonic of the electron cyclotron frequency, ray paths almost identical to those calculated near the plasma frequency can return energy to a satellite moving through the topside ionosphere. An additional type of ray path is also found. When the upper hybrid is greater than the second harmonic, the returning ray paths are not found. This is consistent with the observed resonance strength. The possibility of return paths near the frequency where the Bernstein mode disappears is also found.