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Author Topic: 1/2 wave end-fed wire  (Read 1376 times)
KF7ATL
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Posts: 59




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« on: March 17, 2012, 02:16:20 PM »

I am interested in trying a 1/2 wave end-fed wire for portable use, but have never seen one in actual use, so I'm a little unclear on how it is set up. Does it need a tuner, and is it worked against ground, or what?

Garth, KF7ATL
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WX7G
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Posts: 6328




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« Reply #1 on: March 17, 2012, 02:56:38 PM »

It does need a tuner and it is usually, but not always, worked against ground or a short counterpoise.

The PAR EndFedz does not require a tuner and it works against the coaxial cable shield.
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WB6BYU
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Posts: 13578




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« Reply #2 on: March 17, 2012, 05:28:22 PM »

Generally one end of the wire is hoisted into a tree or similar support so it is somewhat
vertical.  You can string it up in other ways as well.  (Tie a weight on the end of a rope
and toss it over a branch and back down, and use that to pull the antenna up, or use
a fishing rod or slingshot.  But don't try to toss the end of the antenna up into the
tree - it doesn't work as well.)

You do need a tuner of some sort because the impedance at the end of the wire is
a couple thousand ohms or so.  Most tuners use a (variable) capacitor and a coil, which
can be hand-wound.  Other approaches include a tapped quarter wave matching stub
like a J-pole (which is also an end-fed half-wave antenna) or a quarter wave of
twinlead.

My first 15m antenna was a twin-lead J-pole and it actually worked quite well.

Commercial units typically use a coil and capacitor for small size.  You can make it
fixed-tuned for one band or variable.


For examples, scroll down to End Fed Half Wave Antennas here:
http://www.geocities.jp/jk7tke502/antennas_album_eng.html

http://www.roue-libre.be/article.php3?id_article=76

http://www.smeter.net/feeding/halfwave-vertical-antenna-tuner.php

http://www.aa5tb.com/efha.html
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W1JKA
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Posts: 1821




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« Reply #3 on: March 18, 2012, 03:24:02 AM »

   WB6BYU covers it all. My practical experience with efhw antennas is having built a few AA5TB coupler/tuners with 40/30/20 meter half wave radiators.These couplers are for qrp power.I do a lot of portable operations and have never needed any type of ground or counterpoise.I am partial to the sloper or vertical configuration and find these antennas work just as well as my par end fedz.

                                         
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