Ground conductivity
Ground conductivity refers to the electrical conductivity of the subsurface of the earth. In the International System of Units it is measured in millisiemens per meter.Ground conductivity is an extremely important factor in determining the field strength and propagation of surface wave radio transmissions. Low frequency and medium frequency 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 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, using electromagnetic induction, so that contaminants do not reach the surface or nearby water supplies.
