Question

Write a short note on surface wave propagation of electromagnetic waves.

Answer 1

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 polarised can travel in this mode.

The horizontal component of electric field in contact with the Earth is short circuited. The radio waves induce current in the ground through which they pass.
There is loss of power in a signal during propagation on the surface of the earth due to partial absorption of energy by the ground. Loss of energy is also due to the diffraction effect.

The absorption of energy is high for high frequency. Hence, ground wave propagation for low frequency and medium frequency.
It is used for local broadcasting, e:g, ship communication and FM signals (HF), ground wave propagation is nor use.