A tree-suspended Yagi

Last week the postwoman delivered an interesting QSL card from Leroy N7EIE. A brief note on the card indicates that Leroy had been using a triband Yagi suspended from trees for our QSO. I had to know more!

I’ve had a similar idea myself and was therefore pleased to know that someone out there had the actual fortitude to put such an idea into practice.

A few emails later…what can I say – amazing!  Not as convenient to rotate but Yagi performance without the hassles and expense of a tower.

Leroy was kind enough to not only answer my questions and provide photos of the initial installation but to allow me to post them here as well.

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What gave you the idea to install a Yagi this way?

When we put in a bid for this house in 2002, a LARGE reason was the veritable mini-forest of (6) fir trees in the back yard.  They were 100+ feet then and are even bigger now.

In the fall of 2006 I paid Mac the Tree Guy $1200 to bring in his 80′ bucket and install 3/8″ eye-bolts in the side of each of those trees at a height of 80′, with nylon ropes through the eye-bolts.

Three of those trees are about 20′ south of the house, and in a triangular arrangement, about 15′ to a side, which JUST happens to be the turning radius of a TH3DX Mark 4 tri-band beam.  My son James dubbed it Jupiter 2 because it looks like it belongs in outer space, and I already had a VHF beam, which he also dubbed Jupiter 1. 8-)

As you can see from the photos, I ran 3 3/8″ ropes up through pulleys at those eye-bolts at 80 feet then down to clevises on a 3″ washer underneath a pipe-cap on the top of the mast onto which the beam is attached.  Last summer I built my J2J (Jupiter 2 Jig) in which to store the beam for maintenance and between major contests.

Are you able to rotate the antenna from the ground?

Yes, I have a rope attached to a steering bar pointing in the direction of the beam. I usually just leave it pointing SE for stateside contests, but for DX contests I swing it around to Europe in the morning, then Japan in the evenings.

How high is it?

That can vary, of course, as to how many times I hoist up the ropes – one at a time – in a series of upper-body-strength-building-exercises (each rope has about 75 lbs of weight on it) the week before each contest. Usually I get it up to 30-40′ and quit. Performance is quite satisfactory on EVERY contest! Beats the hell out of my G5RV! Much higher than that I would run the risk of popping the eye-bolts during a wind-storm.

 I’ve even pondered putting a Yagi in a tree, rotator and all.

Me too, at first. But the rotator thrust bearings would have to have the weight of the beam ABOVE the rotator. If you can figure out a way of hoisting the rotator up by ropes without getting the ropes caught in the rotated beam, let me know. Possibly a rather large (20′ square) platform underneath with a much larger support tree set-up than I have.

We have about a dozen tall pine & oaks in our yard around 100 feet tall.

They should work, John. Just bear in mind that trees are living (breathing(sort of)) life-forms that grow, sway in the wind, imbed themselves in dirt, and catch diseases. And, as James says, where you have trees, you have limbs. Indeed! The first winter I left it up a 50 lb. limb came down and crashed into the active element, bending it badly. He bent it back later, but it is still a little mis-shapen.

If you have any photos you could email, I’d sure be interested in seeing them.

These were taken last summer right after I build my J2J, and hoisted up the beam from the jig.

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  5 comments for “A tree-suspended Yagi

  1. January 2, 2012 at 10:52 am

    Superb ingenuity! I see many applications and great adaptation given local resources.

    73, DRR

    • January 2, 2012 at 11:06 am

      Yep, he’s got a lot of possibilities, including many lowband options. My tall pines look like bonsai trees by comparison.

      • January 2, 2012 at 2:29 pm

        Indeed! I have my G5RV and 40 meter dipole supported by ropes also through eyebolts on those other 3 pine trees I mentioned. And, yes, it is GREAT having 6 (wooden) 100+ foot towers in my back yard! ;-)

  2. January 2, 2012 at 2:26 pm

    Thank you, I was pondering it many months before I ever took the ‘Mac the Tree Guy’ leap, and never looked back. Yes, I have all the normal beam antenna issues after 6 years of operation in rainy Washington, but I still love it!

  3. January 3, 2012 at 11:38 am

    While I’ve often thought of erecting fixed-position wire beams in trees, I had never considered the possibility of suspending a regular Yagi this way. Very ingenious!

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