What are the three fundamental propagation in Wireless transmissions ?

Wireless transmissions propagate in three modes. They are −

• Ground-wave propagation
• Sky-wave propagation
• Line-of-sight propagation

Ground wave propagation follows the contour of the earth, while sky wave propagation uses reflection by both earth and ionosphere.

Line of sight propagation requires the transmitting and receiving antennas to be within the line of sight of each other. Depending upon the frequency of the underlying signal, the particular mode of propagation is followed.

Examples of ground wave and sky wave communication are AM radio and international broadcasts such as BBC. Above 30 MHz, neither ground wave nor sky wave propagation operates and the communication is through line of sight.