PROPAGATION OF ELECTROMAGNETIC WAVES

Explanation

When the radio waves from the transmitting antenna propagate along surface of the Earth to reach the receiving antenna, the wave propagation is called ground wave propagation or surface wave propagation.
Electromagnetic waves which are vertically polaised can travel in this mode.
The horizontal component of electric field in contact with the Earth is short circutied. The radio waves induce current in the ground through which they pass.
There is loss of power in a signal during its propagation on the surface of the earth due to particle absorption of enery by the ground. Loss of energy is also due to the diffraction effect. The absorption of energy is high for high frequency. Hence, groundwave propagation is suitable for low frequency and medium frequency.
It is used for local broadcasting, e.g., ship communication and radio navigation. For TV and FM signals (signals of very high frequecy), groundwave propagation is not used.