[AMRadio] Windom Antenna


Peter Wittenberg k2lrc at erols.com
Thu Dec 30 06:16:06 EST 2004


Mike, I would be interested in a copy of that article.
Best 73's Peter K2LRC

Mike Dorworth, K4XM wrote:
> Okay, let us try again. I thought the question was.." how can it be
> RESONANT" at more than one place..Mr. Windom clearly shows that it is and
> how to prove it. A antenna cut for twenty works great on 10, a forty meter
> job works great on twenty and ten, an 80 meter works 80-40-20-10 etc. It is
> always RESONANT on all harmonics.The single wire feeder shows about 600 ohms
> to ground and is worked against ground from the link or output. If the wire
> were fed in the center of the antenna, then the antenna WOULD NOT RADIATE at
> all, only acting as a top load capacitance. Also the length of the feeder is
> of no matter and 1200 feet works fine. Sure there is a little radiation from
> the feeder, but not too much. The straight away part insures that the RF
> picked up from the antenna  (SORTA ) cancels out..These antennas work well
> with old Boat Anchor PI-Network outputs, those that go to 600 Ohms. There
> are no Standing waves on this type of antenna to feeder connection on the
> FEEDER!..I can e-mail the original QST article as an attachment (jPEG) for
> those wishing to read further on Mr. Windom's discovery.. Happy antenna
> experimenting in '05..73 de Mike, K4XM
> ----- Original Message -----
> From: "Geoff/W5OMR" <w5omr at w5omr.shacknet.nu>
> To: "Discussion of AM Radio" <amradio at mailman.qth.net>
> Sent: Monday, December 27, 2004 12:28 PM
> 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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>>
>>
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>>
> 
> 
> 
> 




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