Typical Soil Characteristics of Various TerrainsAuthor: R.J.Edwards G4FGQ © 15th February 1998
|TYPE OF TERRAIN||RESISTIVITY
|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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