Re: NEC-LIST: ground conductivity of grassy soil

How much benefit would there actually be? Skin depth at AM BCB frequencies
would run maybe 20 to 40 feet IIRC, making me wonder whether keeping the
upper foot or two of topsoil wet will help much. Ditto the foot of bentonite
around ground rods.

Chuck

-----Original Message-----
From: nec-list-bounces+charlesh3=msn.com_at_robomod.net
[mailto:nec-list-bounces+charlesh3=msn.com_at_robomod.net] On Behalf Of Jim Lux
Sent: Wednesday, August 06, 2008 9:28 PM
To: nec-list_at_robomod.net
Subject: Re: NEC-LIST: ground conductivity of grassy soil

Quoting GrantBingeman_at_cs.com, on Wed 06 Aug 2008 05:11:52 PM PDT:

> Here is another interesting question that just cropped up: can the ground
> conductivity at standard AM broadcast band frequencies be improved
> near a tower
> if dry, barren earth is enhanced with a crop of live, green grass
> that is kept
> moist with an agricultural sprinkler system? g
>

Sure. conductivity (and epsilon, too) are strongly affected by
moisture content, more so in soil with high clay content than sand.

You could go to one of the standard material property tables and see
how much sigma changes, then run a model and see what the change in
loss is.

http://home.earthlink.net/~w6rmk/soildiel.htm has some numbers

Might be more expensive than other approaches for the amount of change.

The other more subtle effect has to do with skin effect/depth.

Jim Lux

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