I've ordered my copy of NEC 4.1 for some serious modeling, but...
Off hand, I'd guess that insulated makes no difference. You're going to be
capacitively coupling to the soil as much as resistively. Skin effect makes
the wire look like a tube, so resistivity only decreases linearly with
increasing diameter, not as the square.
I found my copy of the QST from last year, and the previously referenced
papers that it cites. I'm going to, over the next couple days, work out a
generic model to see if the optimum scheme that Sommers figured out will
noticeably vary.
Essentially, the radials reduce the effective resistivity of the soil. Since
the current density is lower the farther out you get, the value of radials
(increased conductivity) is less, so there's a natural matchup of the
farther spacing of radials and the less need for low resistance as you move
away.
----- Original Message -----
From: "Tom Champlin" <w0hh@msn.com>
To: "Towertalk" <towertalk@contesting.com>
Sent: Monday, December 22, 2003 4:24 PM
Subject: [TowerTalk] Ground radials
Did any one ever decide which was best, bare wire radials or insulated. I
have several thousand feet of #14 stranded with insulation. I also have a
few hundred feet of #6 bare copper. Does it matter which is used? This will
go under a Big SteppIR vertical next spring. I want to wring everything out
of this antenna that I can.
Thanks,
Tom W0HH
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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