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Old Sep 03, 2012, 08:24 PM
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GliderJim's Avatar
Michigan, USA
Joined Jul 2006
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72 MHz antenna question.

I'm putting together a 48" EPP flying wing and the plans show the receiver going in the middle with the antenna running out to one wing tip. Since the antenna is longer than 24" there will be some hanging out the tip.

I could keep the entire antenna within the wing if it were attached to the receiver in the center, in sort of a "Y" configuration.

Anyone know what the ramifications of this are? Or what rules I need to follow?

Jim
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Old Sep 03, 2012, 09:01 PM
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Jim:

I have an Alula, and the antenna on that one goes outboard along the spar, then back in board along the aileron hinge. In my DLGs, when I was still using 72, I let the antenna dangle out the back. Some people wind it around a soda straw inside the fuselage, and I once recieved a little bobbin-like device, and the idea was to wind it around that.

Just don't bunch it up, and you should be fine. Do a range check before flying.

Yours, Greg
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Old Sep 03, 2012, 09:20 PM
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I've flown with part of the antenna near the receiver coiled up like that. Worked fine for me, not clear to me if it matters what receiver so range check of course. I also used a "base loaded" antenna meant for rc cars for some years in an hlg that was often flown pretty far out. No trouble. YMMV
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Old Sep 03, 2012, 09:39 PM
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Joensuu, Finland
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Quote:
Originally Posted by GliderJim View Post
I could keep the entire antenna within the wing if it were attached to the receiver in the center, in sort of a "Y" configuration.
This won't work.Think of the signal as a standing wave of voltage along the antenna wire. The wire is dimensioned so that the nodes of maximum voltage are at the tips of the wire, at the middle the voltage is zero. You wouldn't get any signal if you connect the rx feed there. It is possible to construct a center-fed antenna, but it will need to be dimensioned differently than a simple dipole. I haven't researched this enough to give any specific design data - if you'd like to try it, I'd recommend asking in the electronics or radios forum.
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Old Sep 03, 2012, 09:42 PM
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I just used to run it out toward one tip then back toward the other. Generally with a faomie you are far from stretching the range so worked fine.
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Old Sep 04, 2012, 02:53 AM
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So Cal
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I've had a 48" combat wing and an electric flying wing, and set both up similar to what lesterpk's drawing shows. Never had a problem.
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Old Sep 04, 2012, 07:08 AM
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Michigan, USA
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Well alrighty then - looks like I'll just be running it out and back.

Thanks!
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Old Sep 04, 2012, 02:50 PM
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GliderJim:

What I did with the Alula is almost exactly what lesterpk shows.

I'd say you're good to go.

Yours, Greg
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