Waves travelling over land interact with the earth's surface.

Norton: For propagation over a plane earth,

where

R_c is the reflection coefficient,

E_0i is the theoretical field strength for free space

F(×) is the (complex) surface wave attenuation

D is the phase difference between direct and ground- reflected wave

Received Electric Field =

direct line-of-sight wave +
wave reflected from the earth's surface +
a surface wave.

The (phasor) sum of the direct wave and the ground-reflected wave is called 'space wave'

www.WirelessCommunication.NL © Jean-Paul M.G. Linnartz, 1993, 1995.