[600MRG] Ground Conductivity -

[Brian Pease]

For a fair comparison, both the radials and the sea water would need to 
extend all the way to the receiving station.  Normal radials just reduce 
ground losses close to the antenna where the fields are strong, and 
provide a low impedance reference for insulated verticals.  This 
improves efficiency, but doesn't change propagation.

On 2/7/2016 8:31 PM, Frank Lotito wrote:
> " ground conductivity in the U.S. ranges between 0.5 and 30 millimhos (or millisiemens) per meter.  The conductivity of seawater is 5,000 millimhos per meter, resulting in the best propagation of AM signals."
> ......
> The above was copied from the FCC's recent publication on ground conductivity (https://www.fcc.gov/media/radio/m3-ground-conductivity-map)
> ................
> Obviously, the "gold standard" for ground conductivity is salt water.  I have a question - If one were to lay out 120 equally spaced radials, each a half wave long from the base of a vertical antenna, what would the estimated ground conductivity be compared to "seawater"?  For a more modest radial system, what does it take to achieve a conductivity of say 500 milliohms, which is almost 20 times better than the best ground conductivity in the US, but still one tenth that of seawater?
> ........
> 73 Frank K3DZ / WH2XHA
>
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