[TowerTalk] vertical antennas

[Maurizio Panicara]

To me this appear only a formal controversy.
The current density with a quarterwave vertical and quarterwave radials a
quarterwave off the vertical base is infact quite limited. Where the radial
screen has to resemble a solid screen is where the current return path is
significative, therefore the 50/60 radials perfectly match with the
requirement of spaces that doesn't exceed  0.025 wl between wires.
In my opinion even less radials than 50/60 perfectly work for amateur
purposes with losses that aren't really significative.
We have to keep in mind that obtained an efficiency of 80/85 % the
improvement to the famous 112 radials (96% eff.) is anyway marginal beeing
less than one dB and the extra radials do nothing with the reflections at
many wl away.
Insured a good efficiency, the enviromental ground conditions (i.e. sea
water) and not the radials set the very low angle power density and often
determine the outstanding performances with DX traffic.

73,
Mauri I4JMY



----- Original Message -----
From: "Bill Coleman" <aa4lr@arrl.net>
To: <W8JI@contesting.com>; "Rick Williams" <richardw@mho.com>;
<towertalk@contesting.com>; "Guy Olinger, K2AV" <k2av@contesting.com>
Sent: Friday, November 02, 2001 3:52 PM
Subject: Re: [TowerTalk] vertical antennas


>
> On 10/24/01 8:32 AM, Tom Rauch at w8ji@akorn.net wrote:
>
> >RCA spent a fortune on studying this, and they concluded 50-60
> >1/4 wl radials acted like a solid plate. The key is to not let the open
> >spaces exceed about .025 wl between wires. That even works with
> >a screen reflector antenna!
>
> I don't mean to disagree with Tom, whom I have the highest respect for,
> but the math doesn't quite work out.
>
> If you have 1/4 wl radials, you create a circle or radius 1/4 wl, with a
> perimeter of pi/2 wl. (eg 2 pi r )
>
> Now, pi/2 wl divided by 50 is pi/100 -- which is 0.0314159..., and pi/2
> wl divided by 60 is pi/120 -- which is 0.02618. Close, but not quite
> 0.025.
>
> That would tend to indicate you can have ultimate spacing a bit larger
> than 0.025 wavelength -- perhaps as much as 0.030.
>
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
>
>
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List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!!  http://www.anwireless.com

-----
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