Features of Forecasting the Operation of Ionospheric Radio Lines in Upper Rays Modes

The frequency dependence of transmitted information qualitative indicators is analyzed on the
example of two meridional radio links: single-hop (~2600 km) and dominant two-hop (~5100 km) for basic
modes of radio wave propagation in the ionosphere. It is shown that the presence of highly efficient receivingtransmitting
antennas in a radio communication system leads to the need to take the existence of a priori energetically
extremely weak modes into account in the problem of radio path specification statement. In this
case, we consider those formed exclusively by the mechanism of radiation transfer along the upper-angles ray
trajectories in the ionospheric propagation of radio waves. If the angles of departure and arrival for such
modes and the directions of the main lobes of the antenna patterns at the end points of the radio path coincide,
the signal-to-noise ratio for the wave field can reach the required threshold value and ensure the successful
operation of the radio communication system. This may expand the upper frequency limit for the passage
of radio waves in the transition regions of jump propagation of radio waves in the ionosphere; it should
be taken into account in forecasting the operation of ionospheric radio links.