[AMRadio] Windom Antenna


John Coleman wa5bxo at pctechref.com
Mon Dec 27 14:37:43 EST 2004


YES Jeff 

The feed line is part of the ant and does a lot of radiating.  The Windom is
not a good ant for your residential area.  It generally works against an
earth ground but it might be possible to feed it with a balanced and tuned
1/4 or 1/2 wave balance line and just attach it to one side leaving the
other side open.  Don, K4KYV has some experience with a end fed unbalanced
Zepp and may be able to enlighten you more on the characteristics of such as
this.  Of course the End fed Zepp is something of a all band antenna in it's
self.

John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Geoff/W5OMR
Sent: Monday, December 27, 2004 11:29 AM
To: Discussion of AM Radio
Subject: Re: [AMRadio] Windom Antenna

> In QST magazine for September 1929 the original Windom Antenna article
> starts on page 19. It clearly shows that it is exactly resonant on all of
> it's design bands, so long as there is an harmonic relationship.
80-40-20-10
> etc. There are diagrams included which show how this is determined with an
> RF ammeter and a rolling trolley after which very precise and repeatable
> formulas were derived. Of course this is the single wire fed version. The
> later 300 Ohm job is merely wishful thinking.The length in feet is always
> 468, divided by desired frequency in Kc. For the lowest desired band. The
> tap is always feet times 25 divided by 180. I might add that antennas put
up
> as temporary during this nasty winter weather last 20 to 30 times longer
> than summer installed permanent antennas. happy antenna experimenting. 73,
> K4XM, Mike.

So, in order for this to work, you have to decide what frequency you're
going
to operate on, on the HIGHEST frequency the antenna will cover.

ie: 29MC /2 = 14.5, 7.25, 3.625, 18.125Mc.

that being the case, then
L = 468/f(L)
L = 468/18.125
L = 258.20689655172413793103448275862

Now, you said that the 'tap is always feet times 25 divided by 180'
T = 258.207ft * 25 / 180
T = 6455.17 / 180
T = 35.862068965517241379310344827586

Single wire feeding it?  Fed against Ground?  Doesn't the single feed-line
then
become part of the radiating antenna?

Even if someone were to take, say the output of a link and feed it directly
to
the
open wire feed-line, the open wire line would have to go all the way to the
feed
point of the antenna, wouldn't it?

I'm sorry if I'm seeming a little dense, but I can't get unwrapped from the
'single wire fed version' of this antenna.

Open wire output from the link has *2* wires.  I can see attaching them to
some
open wire line, and feeding this Wyndom antenna at 1.8125, and having the
antenna resonant on 3.6250, 7.250, 14.5 (oops - can't operate there) and
29Mc,
but I simply fail to understand how one wire is going to feed an antenna
thas
has two posts to connect to.

Certainly has me thinking, though.  Now, if I could just come up with land
that
had 300' (for guy supports on both sides)

I'll have to work CW on 3.6250, forget about 20m and enjoy a
multi-wavelength
antenna on 10m (when the band is open).  Pardon the sarcasm ;-)


Seriously, here. Surely, there must be something I'm missing, to be able to
use
this antenna on all bands, with acceptable VSWR.

'Splain it to me, please.

Happy New Year

73 = Best Regards,
-Geoff/W5OMR


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