FW: [Antennas] Quick and Cheap

Sun, 21 Apr 2002 18:48:36 -0400

Don't forget to factor in the difference in diameter of the pipe.  Not much
effect at say 160 or 80M, but noticeable to the antenna length calc at 10M
and above....

I doubt you'd consider pipe for 40 or 80M use.... so for 2M or higher, the
pipe diameter is starting to become a noticeable percentage of wavelength
and would make the antenna slightly shorter than the calc.  I've seen
programs about that do factor in wire size or diameter, but can't lay my
hands on them right now.,.....

<<---  END OF MESSAGE --->>
----- Original Message -----
From: "Jerry Flanders" <[email protected]>
To: "Adam Farson" <[email protected]>; "Antennas Reflector"
<[email protected]>
Sent: Sunday, April 21, 2002 12:04 AM
Subject: Re: FW: [Antennas] Quick and Cheap

> I asked this question on the rec.radio.amateur.antenna newsgroup a few
> years ago and learned that, as you say, the resistivity is MUCH higher for
> the galvanized coating. BUT - if the surface area of the galvanized
surface
> is, for example 10x the surface area of a #12 copper wire and the RF
> resistivity of the copper is one-tenth, the larger surface area pipe has
> the same loss as the smaller wire. Because of the very large surface area,
> I would guess that a 1.5 inch galvanized pipe would have considerably less
> RF resistance than a #12 copper wire, therefore would work well as a
radiator.
>
> Jerry W4UK
>
>
> At 10:18 PM 4/18/02 -0700, Adam Farson wrote:
> >Tim,
> >
> >Galvanised pipe will probably be very lossy. Owing to skin effect, most
of
> >the RF current will flow through the zinc coating. Zinc is not famous for
> >its low resistivity and will certainly degrade quite rapidly with
exposure
> >to the elements.
> >
> >You will certainly be much better off with aluminium or copper tubing (my
> >spell-checker is set to UK English). Copper water-pipe will work fine.
> >
> >Best 73,
> >Adam, VA7OJ/AB4OJ
> >North Vancouver, BC, Canada
> >http://www.qsl.net/ab4oj/
> >Note new e-mail address:
> >mailto:[email protected]
> >
> >
> >-----Original Message-----
> >From: [email protected]
> >[mailto:[email protected]]On Behalf Of Tim Billingsley
> >Sent: Thursday, April 18, 2002 14:42
> >To: [email protected]
> >Subject: [Antennas] Quick and Cheap
> >
> >
> >How well will galvanized thin wall pipe radiate??
> >
> >Specifically top rails for chain link fencing(used as a vertical on 10 15
or
> >20
> >
> >
> >---
>
>
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>
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