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I'm looking at designs for low cost DIY yagi antennas for a fox hunt, and pondering coat hanger wire and PVC piping. I'd like them to be built by the youth who will be doing the fox hunt, but that requires some safety considerations.

If I plan to bend the tips of the coathanger wire back on themselves to avoid safety issues with the sharp ends, will I cut them to length prior to the bend, or should they be at length after the bend? The bend will be about a plier's width of material, so maybe 5-8 mm, turned back 180 degrees, or nearly so.

I don't have equipment to test for antenna matching, so I can't experiment on this, however these will be used for hunting, not transmitting, so I don't expect it's going to be critical. I'd like to get close, though.

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I would bend the tips back, twisting the free end around the standing end so you make a loop with good electrical contact between them. Measure from the base to the end of the loop for the purposes of calculating the length. The loop is almost entirely cosmetic and won't affect the electrical length of the antenna much.

If you were to make the loop bigger, you would have a capacitive hat, which would electrically lengthen the antenna. However, if you keep it small, and you fold it back and short the end back to the antenna, the capacitance added at the end will be negligible.

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    $\begingroup$ Note that it's a good idea to rough up the ends with sandpaper or steel wool to ensure electrical contact. Oxidation and other coatings could interfere otherwise. Best would be to solder it together where the end bends back. $\endgroup$
    – KD8TGR
    Nov 27, 2013 at 15:13
  • $\begingroup$ Agree with @KD8TGR; most of the coat hangers I see from like the dry cleaners have a coat of clear lacquer or are painted. $\endgroup$
    – WPrecht
    Nov 27, 2013 at 17:08

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