Gary & others,
Thanks for all the input so far on the loop. I
neglected to post the basis for my loop project. I
have read a lot of information from Cebik and others
on loops. The main article that intrigued me for this
project is as follows:
"Do the VOMBA! Vertically Oriented Multi-Band
The section that I am using for my project is titled;
"The Hybrid Triangle"
The article used a 40 meter loop for its discussion
and I took the dimensions and constructed a 80 meter
loop. That is where I got the 1050/f.
I had originally thought of doing a 80 meter vertical
rectangle loop, but saw the article on the hybrid.
Gary thanks for the input on your modeling and yes I
am "Guilty as charged" for being dangerous with wire.
I have not learned to model antennas, but I am
interested in learning. If you know of a good
One other thing that I forgot to mention is that I am
using 12 ga insulated uf irrigation wire. I am in the
irrigation business so have plenty on hand. I can also
string it through the trees (also can be rather
stealthy that way) without any grounding to the trees.
If the insulation on the wire makes a difference in
length, please advise.
I usually try to put up wire that is outside the
normal box. I have a 80 meter double extended zepp at
the cabin, a little unwieldy at first, but now have it
under control. This plays really well for dx.
Yesterday, at 22:00z had 2 contacts into Japan on 15
meters...one I listened for 30 minutes and then qso'd
with him for another 20. Unbelievable propagation.
Nothing else on 15 meters at the time.
Sorry for the use of bandwidth.
I look forward to your comments.
> Message: 1
> Date: Sat, 6 Nov 2004 13:26:50 -0500
> From: "Guy Olinger, K2AV" <email@example.com>
> Subject: Re: [TowerTalk] 80 Meter Hybrid Triangle
> To: "K0PYK" <firstname.lastname@example.org>, "Tower Talk"
> Message-ID: <022b01c4c42e$2ebf86a0$0500a8c0@swift>
> Content-Type: text/plain; format=flowed;
> ----- Original Message -----
> From: "K0PYK" <email@example.com>
> > The configuration is, from the connection
> > feet up vertically...120 feet cross the top
> > horizontally...them angle back down to the
> > point.
> > * I have seen different formulas thrown
> > 1050/f the correct one for this loop?
> > * What is the best way to feed this loop? Coax,
> > line, 1/4 wave 72 ohm...etc. I have a tuner in
> > rigs.
> Hi, Tom.
> I modeled this (only three wires, so no big sweat).
> 1) Shows a feed Z of 30 ohms at 3.6 MHz. Close
> enough to the resonance
> point but I'm not sure what Z you were expecting
> 2) Overall pattern gain (perfect = 1.0) is 0.23 or
> -6.47 db, rather
> like a vertical with a poor radial field. The losses
> are almost
> entirely vertically polarized ground losses within
> two or three
> 3) With that in mind, the gain of the main lobes is
> only 0.65 dbi.
> 4) The radiation pattern is irregular, a) with
> moderate cancellation
> of high angles, b) main lobes broadside to antenna
> are vertically
> polarized because the long horizontal runs have
> current distributions
> nearly equal and out of phase broadside and cancel
> both out and up.
> 5) With the specified feed point, the two horizontal
> runs do little
> other than act as a device to provide a non-ground
> current sink for
> the coax shield, and a top hat for the short
> vertical section.
> 6) if you want to match specified impedances with
> coax, close the loop
> at the bottom and feed the sloping section at
> various distances from
> the bottom. In the model,
> 50 ohms is found out approx 23 feet. (1:1 balun)
> 100 ohms is found out 37 or 38 feet. (1:1 balun and
> electrical 1/4
> wave of 75 ohm coax)
> Either of these matching points is narrow (because
> the vertical
> section is short) with a 2:1 bandwidth of only 75
> khz or so. You will
> need to shorten or lengthen the horizontal sections
> to tune to desired
> center. You should keep the vertical section as long
> as possible.
> The 200 ohm point is touchy and problematic. (4:1
> Moving the feed and therefore also the current max
> out the sloping
> section starts to modify the pattern and allow some
> high angle
> radiation. It also mildly reduces the ground loss.
> The 50 and 100 feed points produce a hemispheric
> pattern broadside
> that will fill in local coverage without any
> reduction of the low
> If one wants to put up antennas of this sort, it
> really is time to get
> a copy of EZNEC (or ....) and start modeling.
> Without it, it's just
> throwing up wires blind and hoping.
> There is an adjustment to this design that produces
> a far more
> satisfactory result. I will post that later.
> 73, Guy.
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