Features of Radio Emission Propagation in the Ionosphere under Conditions of Threshold Nonlinearity

The well-known problem of nonlinear wave–ionosphere interaction under conditions of threshold nonlinearity is considered. It is believed that nonlinear effects arise only for high-power radiation, when the wave amplitude exceeds a certain threshold value. The possibility of the existence of concentrated wave fields under these conditions is shown. It is revealed that a certain ratio of nonlinearity parameters leads to an increase in the radio emission intensity, since the interaction of individual solitons can lead to their merging into a higher-power solitary wave. The presence of threshold nonlinearity can lead to the formation of an ordered structure of solitary waves.