Radio signals are transmitted in a tight beam aimed at the tropopause, midway between the transmitter and receiver sites; as the signals pass through the troposphere some of the energy is scattered back toward the Earth, allowing the receiver station to pick up the signal.
Radio signals are transmitted in a tight beam. This tight beam is aimed at the tropopause. This was midway between the transmitter and receiver sites. Some of the energy is scattered back toward the Earth. Some of the energy was allowing the receiver station. This was to pick up the signal. The signals pass through the troposphere.