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Old August 12th 07, 02:27 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Confused over coax and windom - newbie

Dave Platt wrote:
In article ,
Jimmie D wrote:

I never could really figure out a windom except that the origional was just
a flat top that was tuner friendly on all the ham bands.


As I understand it, the original Windom is essentially a vertical
radiator, with an asymmetrical capacitive "top-hat" (which will
probably radiate at least a bit because of its asymmetry), bottom-fed,
working against the station's RF ground. It's simply a form of
Marconi antenna.

The "Carolina Windom" is a very different sort of antenna... AIUI it's
a off-center-fed doublet which (by design) also has some
vertically-polarized radiation from the upper portion of its coaxial
feedline.

Although the two have a superficial resemblance, I believe that the
two types have very different distributions of RF current, feedpoint
impedances, and (probably) radiation patterns and polarization
distributions.


Yes, my 1957 ARRL Handbook makes the distinction between
the single-wire feed of the Windom vs the transmission
line feed of an Off-Center Fed (OCF) dipole. The currents
at the vertical wire to horizontal wire junction in a Windom
are flowing in opposite directions in the horizontal wire.
The currents at the Carolina Windom's coax to horizontal
wire interface are flowing in the same direction, more like
an OCF dipole than a Windom. It was probably a marketing
ploy to call it a "Windom" when it was not. "Carolina OCF"
doesn't have much of a ring to it.
--
73, Cecil http://www.w5dxp.com