Richard Harrison wrote:
Roy, W7EL wrote:
"What conclusions could we draw from that information?"

My comment is a little off topic as it is not about measuring soil
constants. It is only an opinion that the FCC`s decisions regarding a
standard grounding system for medium wave broadcast stations worked out
very well. 120 redials each about 1/4-wavelength seems to work well
whether soil is good or bad.

In summer or winter, if the ground cracks open from drought or is
covered with a foot or more of floodwater, the tower currents and field
strengths hardly change at all. Directional patterns are unaffected.
Amazing and well done!

Well, not exactly amazing, since the FCC deliberately requires the
ground to be covered by so many radials that the location and its ground
conditions don't matter any more.

That was an administrative policy decision rather than a technical one.
From the technical viewpoint, everybody agrees that 120*0.25wl is more
than enough to override the local ground conditions under the tower
irrelevant.

The real technical question is: how many, and how long, will be "just
enough" for "here"? That obviously requires a lot more knowledge and
engineering judgement.

Having just taken delivery of two miles of radial wire, the question of
"How much is enough?" is starting to become very practical...


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek