I also had a full wave 80-meter delta loop a few years ago. I first used
it with a 75-ohn stub for use on 80 meters only and had great success with
it; it was fed in the upper corner. Mine looke like an upside down
pyramid. I later removed the matching stub and fed it with 450-ohm line
for multi-band us with a tuner. It was one of the best antennas I've ever
made, and next spring I'm going to put up one here at this QTH.
73 Buddy WB4M
----- Original Message -----
From: "Jon Casamajor" <firstname.lastname@example.org>
Sent: Wednesday, February 03, 2010 8:09 PM
Subject: Re: [TowerTalk] 80m Delta loop on 70' tower
> Hi Stu,
> I did exactly what you are describing several years ago. I thought I had
> documented the design but, darned if I can find it right now. The antenna
> was a full wave 80m delta loop cut for the low end of the band. I was
> chasing 5BDXCC and CW was where I did most of my operating.
> The loop was pretty much equilateral with the apex at the top of my
> tower. I make it fit, I tilted the loop out probably 10 to 15 degrees. I
> used an Almond tree on one end and a 15' pole on the other end for
> The base of the triangle was probably 12-15' above the ground. I fed the
> loop 1.4 wave down from the Apex on the left side looking at the loop from
> the tower.
> | /\
> | / \ Not to scale but should
> give you the picture. where X is the feed point;
> | / \ The loop was actually
> pretty much equilateral...diagram isn't.
> | / \
> |/ \
> /| \
> FEED POINT ----- X| \
> I used a length of 75 Ohm RG11 I think it was to match the loop and at
> 3.505 it shows about 50 ohms and 1.1:1 VSWR.
> I used this antenna on both cW and phone with a tuner for 75m. it was not
> all optimum on 75, but it would radiate pretty well. On CW this antenna
> an absolute killer and with my Henry 2K-3 I didn't wait in line too long
> pile ups. This feed point will give you vertical polorization so it isn't
> the best receiving antenna in noisy conditions and I often used my 2 el
> Yagi to listen to weak signals with pretty good success.
> Getting one of these loops up and tuned takes some effort, I think I had
> whittle on the length 3 or 4 times but once you have it up and singing,
> will not regret the effort. Mine, unfortunatly came down in a wind storm
> just a couple of years ago and I have never put it back up. It helped me
> get that 5BDXCC which was the mission. The full wave loop is a real
> if you can keep it up.
> I'm sure with a litle research you can find the formula for the RG-11
> matching stub. From memory it was in the neighborhood of 20 something feet
> and I think the design was from one of the ON4UN articles. Good luck, you
> will love the loop on 80m!
> "Politicians are like diapers...they both need changing often and for the
> same reason" Mark Twain.
> -----Original Message-----
> Message: 1
> Date: Wed, 3 Feb 2010 14:28:06 -0600
> From: Stuart Browne <email@example.com>
> Subject: [TowerTalk] Feeding a Delta Loop
> To: TowerTalk@contesting.com
> Content-Type: text/plain; charset=ISO-8859-1
> I'm looking at installing a Delta Loop for 80 m. on my 75' tower. The low
> end of the triangle will be about 20' off the ground ( the tower is on my
> rooftop (flat). I know that the conventional wisdom is a feed point in
> center of the lower side of the equilateral triangle which is around 50
> ohms. ON4UN describes feeding a DL at 1/4 wl from the Apex of the
> to achieve a 23 deg take off angle (which is what I'm after).
> I'm looking for any "real world" feedback as to the pros/cons of feeding a
> DL at the apex, lower center, corner or 1/4wl from the apex.
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