[Top] [All Lists]

[TowerTalk] Re: 80 Meter Hybrid Triangle Loop

Subject: [TowerTalk] Re: 80 Meter Hybrid Triangle Loop
From: K0PYK <>
Date: Sun, 7 Nov 2004 02:53:41 -0800 (PST)
List-post: <>
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 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.
Thanks again!!!
Tom, K0PYK

> Message: 1
> Date: Sat, 6 Nov 2004 13:26:50 -0500
> From: "Guy Olinger, K2AV" <>
> Subject: Re: [TowerTalk] 80 Meter Hybrid Triangle
> Loop
> To: "K0PYK" <>,        "Tower Talk"
> <>
> Message-ID: <022b01c4c42e$2ebf86a0$0500a8c0@swift>
> Content-Type: text/plain; format=flowed;
> charset="iso-8859-1";
>       reply-type=original
> ----- Original Message ----- 
> From: "K0PYK" <>
> > The configuration is, from the connection
> point...40
> > feet up vertically...120 feet cross the top
> > horizontally...them angle back down to the
> connection
> > point.
> > * I have seen different formulas thrown
> around...Is
> > 1050/f the correct one for this loop?
> > * What is the best way to feed this loop? Coax,
> ladder
> > line, 1/4 wave 72 ohm...etc. I have a tuner in
> both
> > rigs.
> Hi, Tom.
> I modeled this (only three wires, so no big sweat).
> Observations:
> 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 
> wavelengths.
> 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
> balun)
> 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 
> angles.
> 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.

Do you Yahoo!? 
Check out the new Yahoo! Front Page. 


See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
and ask for Sherman, W2FLA.

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>