Ground Systems
Soil characteristics

Typical Soil Characteristics of Various Terrains

Author: R.J.Edwards G4FGQ © 15th February 1998

TYPE OF TERRAIN RESISTIVITY
(Ohm-metres)
PERMITTIVITY
Freshwater lakes, unpolluted 1000 80
Sea water, away from river estuaries 0.22 81
Agricultural plains, streams, richest loam soil 30 20
Pastoral, low hills, fertile soil 80 15
Flat, marshy, densely wooded in places 130 13
Pastoral, medium hills with forestation 270 12
Pastoral, heavy clay soils, hills 250 12
Rocky soil, steep forested hills, streams 500 10
Rocky, sandy, some rainfall, some vegetation 500 8
Low-rise city suburbs, built-up areas, parks 1000 6
High-rise city centres, industrial areas 3000 4
Sand deserts, arid, no vegetation > 20,000 3

An ohm-metre is the resistance between opposite faces of a 1-metre cube of the material. The above values are averages taken over large distances.

Permittivity is the dielectric constant relative to air.

These average values may be used to estimate groundwave signal strength over the above terrains, using Sommerfeld's formula, from VLF to HF.

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