Ground Wave Propagation

In ground wave propagation, the electromagnetic waves travel along the surface of the earth. These can bend around the corners of the objects but are affected by terrain.

A vertical antenna is used to transmit electromagnetic waves. If electric field E is vertical, and the magnetic field B is horizontal, the direction of propagation k is horizontal but perpendicular to both E and B vectors.

The material properties of the ground, such as its conductivity, refractive index and dielectric constant, are seen to control propagation of such waves. That is why ground waves propagation is much better over sea than desert.

In practice, ground waves are rapidly attenuated due to scattering by the curved surface of the the earth. A larger wavelength results in smaller attenuation. That is, ground waves are more useful as lower frequencies & constitute the only way to communicate into the ocean with submarines. Moreover, this mode of propagation is suitable for short range communication. For these reasons, ground wave propagation is used for radio wave (300 kHz – 3 MHz) transmission.