Ground conductivity refers to the
electrical conductivity of the subsurface of the
earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. In the International System of Units (SI) it is measured in millisiemens per meter (mS/m).
Radio propagation
Ground conductivity is an extremely important factor in determining the field strength and propagation of
surface wave (ground wave) radio transmissions.
Low frequency (30–300 kHz) and
medium frequency
Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the ...
(300–3000 kHz) radio transmissions are particularly reliant on good ground conductivity as their primary propagation is by surface wave. It also affects the real world radiation pattern of
high frequency (3-30 MHz) antennas, as the so called "takeoff angle" is not an inherent property of the antenna but a result of a
ground reflection. For this reason ITU publishes an extensive world atlas of ground conductivities.
Other uses
Ground conductivity is sometimes used in determining the efficiency of a
septic tank
A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater ( sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatm ...
, using
electromagnetic induction, so that contaminants do not reach the surface or nearby water supplies.
References
External links
Ground conductivity maps in the United States(provided by the
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...
and includes large scale map)
Measurement of the ground conductivity and relative permittivity with high frequency using an open wire line (OWL)(Practical example with network analyzer and mathematics for the conversion)
Broadcast engineering
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