I currently use separate full-size delta loops for 80 & 160
meters. Both of mine are supported at the top (apex) by
a tower. Each of my loops is fed in one of the lower cor-
ners with a length of 75 ohm coax, as a matching section,
to get the impedance converted to 50 ohms.
I used an article in QST from many years ago as a guide
in setting up my loops. I don't know off-hand which
issue it was but if anyone would like to know, I could
find out for them.
I don't know "exactly" how my loops are "polarized,"
but I DO KNOW THAT THEY WORK...on 80 me-
ters, I have somewhere around 267 wkd / 264 cfmd
and on 160 meters, I have 165 wkd / 163 cfmd. I
don't know how much better they might work if I was
to feed them part-way up from one of the corners as is
suggested in ON4UN's (and others') book, but they
seem to work very well for me.
73 es gud DX de Brad, N9EN @ Radio Free Roscoe (IL)
----- Original Message -----
To: <TOWERTALK@contesting.com>; <firstname.lastname@example.org>
Sent: Sunday, September 09, 2001 7:16 AM
Subject: Re: [TowerTalk] Delta Loop Polarization
> On Sat, 8 Sep 2001 "Mike & Coreen Smith" <email@example.com> writes:
> > Hi Tom (et al)
> > Always enjoy reading your posts.
> > My Delta loop as I recall is Vertically polarized. I fed it partway
> > (I think 1/8WL(?)--been 9 years since I crawled into the thick trees
> > installed> it) along the bottom edge.
> Vertical polarization of a Delta Loop results when you feed it
> 1/4 WL down from the apex on one SIDE. Each side is .33 WL.
> Horizontal polarization of a Delta Loop results when you feed it
> at the Apex OR in the middle of the Bottom Wire.
> Offsetting the feedpoint from either of these configurations results
> in both horizontal and vertical components.
> Feed impedance is typically around 100-120 ohms and can
> be matched to 50 ohms through a 1/4 WL (electrical) length
> of 75 ohm coax such as RG-59.
> Tom N4KG
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List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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