Re: NEC-LIST: ground conductivity of grassy soil

May I put in my two cents' worth.

Many years ago I consulted for a government organization in what was then
Rhodesia - long before the current Zimbabwe meltdown. One of the rather
interesting problems that cropped up at an HF site was the way that the antenna
vertical radiation patterns changed with season. It was almost as though it was
being steered in the vertical plane. As evidence the users cited the way that
the primary "target" areas seemed to change distance with season, and cycled
back and forth over the year. Enquiries from people in the know elicited the
information that the ground water level was seasonal, and that it varied quite
significantly in the area where the site was. Voila - seasonal beamstearing. I
hope this adds an extra dimension to the discussions.

Best regards,
Duncan Baker.

-----Original Message-----
From: nec-list-bounces+duncan.baker=ieee.org_at_robomod.net
[mailto:nec-list-bounces+duncan.baker=ieee.org_at_robomod.net] On Behalf Of Jim Lux
Sent: 07 August 2008 05:12 PM
To: nec-list_at_robomod.net
Subject: Re: NEC-LIST: ground conductivity of grassy soil

At 06:51 AM 8/7/2008, Chuck Hutton wrote:
>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

You're probably right. Although, increasing the conductivity will
decrease the skin depth, so if you go far enough, most of the current
will be travelling in the hopefully less lossy surface layer.

-- 
The NEC-List mailing list
NEC-List_at_robomod.net
http://www.robomod.net/mailman/listinfo/nec-list
-- 
The NEC-List mailing list
NEC-List_at_robomod.net
http://www.robomod.net/mailman/listinfo/nec-list