01-06-2012, 12:56 PM
Ground wave propagation
Ground wave propagation.pptx (Size: 148.01 KB / Downloads: 35)
The waves, which while traveling , glide over the earth’s surface are called ground waves.
Ground waves are always vertically polarized and induce charges in the earth.
The number and polarity of these charges keep on changing with the intensity and location of the wave field.
This variation causes the constitution of the current.
Plane Earth Reflection
For a smooth plane and finitely conducting earth, the magnitude and phase of the reflected wave differ from that of the incident wave.
When the earth is rough, the reflected wave tends to be scattered and may be much reduced in amplitude compared with smooth earth reflection.
When the incident wave is horizontally polarized
The phase of the reflected wave differs from that of the incident wave by nearly 180
for all angle of incidence.
For angles of incidence near grazing, the reflected wave is equal in magnitude but 180
out of phase with the incident phase.
As the angle of incidence is increased, both the magnitude and phase of the reflection factor change.
Space wave and Surface wave
Ground wave can be divided into two parts
Space wave
Surface wave
The space wave dominates at larger distances above the earth, whereas the surface wave is stronger nearer to the earth’s surface.