Sky wave communication: It is the mode of wave propagation in which the radiowaves emitted from the transmitter antenna reach the receiving antenna after reflection by the ionosphere. In sky wave propagation, the radio waves of frequency range from generally 1710 KHz to 40 MHz are used. This mode of propagation is used by short wave broad cast service.
The electromagnetic waves of frequencies greater than 40 MHz penetrate the ionosphere and escape.
