Re: NEC-LIST: ground conductivity of grassy soil

Hello Jim,

thanks for that list! I really can use that one. However, I am not
familiar with the E/Eo value... I already looked up some of my
references and really am not so sure what exactly is meant by this
value. Can someone explain me how I can transfer this E/Eo into a
permittivity e_r?

Sorry, this is probably a stupid question, but I just don't know
this one...

Best regards,
Christoph

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 Im Auftrag von Jim Lux
Gesendet: Donnerstag, 7. August 2008 06:28
An: nec-list_at_robomod.net
Betreff: 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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