Re: [TowerTalk] re Radials

["Rob Atkinson, K5UJ" <k5uj@hotmail.com>]

the davis RF price for #16 looks pretty good by current pricing however I am 
a bit leery of the physical robustness of #16.

WOR reportedly tried aluminum at one time and it didn't work out for some 
reason.   Maybe the Al didn't last.

you might think $68 for 1K' isn't bad but if you are putting down 100 1/4 w. 
radials for 160 it starts getting pricey for a ham.  do the arithmetic.

re the 20' radials--a base fed linear conductor perpendicular to earth comes 
under the effect of earth when close, so that earth becomes the mirror part, 
or the missing other half of the radiator.   the massiveness of the earth 
predominates so that any radials buried or laid on the surface aren't the 
"mirror part" so much as they facilitate earth return conductivity by 
helping overcome resistance of earth ground.  Because of that their length 
isn't quite as critical.  If you could levitate the radiator up into the air 
to sufficiently isolate it from earth's surface, then any metal component 
(we'll continue to use radials) intended to be the lower half, or mirror, 
must perform all of the counterpoise or groundplane function and because it 
is a complete antenna component, its length matters.  This is why if you 
place your radiator up say, 10 feet on 40 m. the radial lengths have to be 
measured and cut appropriately.

Studies (I know of at least one IEEE paper on this) have shown that 
unusually short radials on the ground or below grade work almost as well as 
1/4 or 1/2 w radials, but in this case, "short" meant 45 degrees or 1/8 w.   
I think 20 feet is pushing the short envelope.  Also, it is critical that 
you employ lots of radials to enjoy the benefit of having them.  Five or ten 
or twenty is not enough.  From what I have read, if you put down ninety 
radials around 60 feet long, you will enjoy almost the same field strengh in 
mv/meter at one km you would have with the same number of radials 1/4 w. 
long on 160 meters.   Most hams who find ground mounted verticals to be poor 
performers simply do not use enough radials.

rob / k5uj

From: "hasan schiers" <schiers@netins.net>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>,<towertalk@contesting.com>,"Jim 
Lux" <jimlux@earthlink.net>
Subject: Re: [TowerTalk] re Radials
Date: Wed, 14 Jun 2006 09:13:21 -0500

But....aluminum in a lot of soil types will disintegrate in a couple of 
years, so best to know the soil characteristics before making the effort to 
lay a bunch of aluminum down. 68 bucks for a 1000' of #14 THHN insulated 
copper wire is not a fortune, and would last a very long time.

73,

...hasan, N0AN
----- Original Message ----- From: "Jim Lux" <jimlux@earthlink.net>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>; <towertalk@contesting.com>
Sent: Wednesday, June 14, 2006 8:56 AM
Subject: Re: [TowerTalk] re Radials


> At 06:29 AM 6/14/2006, Rob Atkinson, K5UJ wrote:
> > It depends on whether or not you either bury them, lay them flat on the
> > ground or elevate them a significant distance in terms of wavelength.  If
> > you bury them or lay them on the ground the 40 meter 1/4 w/l will be okay
> > on 20.  If you elevate them (for 7 mhz 6 feet would probably be okay) then
> > I think you need radials cut to each band you want to operate.
> >
> > If you haven't bought your wire yet, you'll have to rob a bank first.  I
> > heard last night that #14 and #12 cu wire prices have gone to the
> > moon.   A guy I know paid $90 for 500' of #12 at one of the big box
> > stores.  500' of #14 is around $40.  It was $15 two years ago.
>
>
> Yes indeedy.. copper prices have shot through the roof.  Starts to make
> aluminum electric fence wire look more attractive.  60% of the conductivity
> of copper, but less than half the price, so just lay twice as much. (Labor
> is free on ham antenna projects, right?)
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

_________________________________________________________________
Is your PC infected? Get a FREE online computer virus scan from McAfee® 
Security. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk