|[AMRadio] Windom Antenna|
w5omr at w5omr.shacknet.nu
Mon Dec 27 12:28:32 EST 2004
> 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
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,
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