Re: [TowerTalk] GROUND RADIAL SYSTEM MAGAZINE ARTICLES

[Jim Lux <jimlux@earthlink.net>]

At 02:40 PM 12/22/2003 -0600, hasan schiers wrote:
> In QST sometime in the last 3 or 4 months there was an EXCELLENT article
> that showed how to put down the most efficient radial system for any given
> length of wire you have available. It's based on the famous Brown study, and
> I found it to be one of the quickest and most efficient ways to practically
> determine how to lay out your radial field for a ground mounted vertical.
>
> For some reason, I haven't seen it mentioned....and it is based on the best
> empirical study ever done on radials for ground mounted verticals. I wrote
> the equation into a simple (one cell) excel spreadsheet, and by simply
> inputting how much wire you had available to bury, it reveals the number and
> length of radials that will produce the least ground loss. (The equation is
> clearly displayed in the first few paragraphs of the article.)
>
> The article has a lot more info in it, including graphs to give you a feel
> for the actual losses involved and recommendations at the end. That single
> equation, however, makes reading the entire article well worth the trouble.


The Brown study was for ground wave at roughly 1 MHz, not for skywave at 
3.5 MHz and higher.  The advice in the article is fine if you're building 
an AM broadcast station.

The optimization in the QST article was for various gauges of wire and 
length and made some fundamental assumptions about soil conductivity and 
what the current distribution would be, ultimately drawing on Brown's work, 
which, again, was for frequencies around 1 MHz.  I don't have it in front 
of me, but as I recall, either the author of the most recent QST article, 
or the previous ground radial article a few years back, also rolled in the 
induced ground return current distributions (that is, most of the return 
current is close to the base, so there's a diminishing returns as you get 
farther out), once again derived from Brown.

To be useful, the optimization should really figure out what's the best 
approach for a given expenditure of time and money. Copper wire, to a first 
order, is priced by the pound.  Are you better off buying a lot of thin 
wire or a little bit of thick wire? Labor to a first order is proportional 
to total length of all the radials combined(you've got to slit/trench/lay 
the wire).

If you're trying to minimize resistive ground losses, it's not a trivial 
computation, because of skin effect, both for the soil and for the wire 
you're using (thin wire gives you more total feet of wire, for a given 
weight of copper, but skin effect losses are greater, and there's less 
surface area of the wire in contact with the soil)




> ...hasan, N0AN
> ----- Original Message -----
> From: "GALE STEWARD" <k3nd@yahoo.com>
> To: "towertalk reflector" <towertalk@contesting.com>
> Sent: Friday, December 19, 2003 9:13 AM
> Subject: [TowerTalk] GROUND RADIAL SYSTEM MAGAZINE ARTICLES
>
>
> > I dug thru my archives and came up with the following
> > articles that I've saved over the years. There might
> > well be more out there but this was all I have.
> >
> > "Short Ground-Radial Systems for Short Verticals" by
> > Jerry Sevick, W2FMI. QST, April 1978
> >
> > "Optimun Ground Systems for Vertical Antennas" by John
> > Stanley, K4ERO. QST, Dec. 1976
> >
> > "Radial Systems for Ground-Mounted Vertical Antennas"
> > by Brian Edward, N2MF. QST, June 1985
> >
> > "Ground Systems for Vertical Antennas" by Al
> > Christman, KB8I (now K3LC). HR, Aug. 1979
> >
> > "Efficient Ground Systems for Vertical Antennas" by
> > K8CFU, W3ESU, and K4HU. QST, Feb. 1983
> >
> > A lot of good, practical information in these.
> >
> > Happy Holidays,
> > Stew K3ND
> >
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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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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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