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Author Topic: mobile hf antenna... length or resonance?  (Read 4300 times)
WB4JZY
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Posts: 76




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« on: August 21, 2014, 08:57:39 AM »

I have a homebrew mobile antenna on my RV.   It has a 4 foot aluminum lower section, then a loading coil, then a capacity hat and then topped off with a 20 foot telescopic whip. It is fed with a 20 foot length of coax. When I am parked and let say working 20 meters,  is it better to adjust the coil and whip length for  resonance or extend the whip out to max length, bypass the coil and use a tuner at the xmitter?  My gut tells me that losses would not be that great and it is better to have more metal up in the air?
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KB1GMX
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Posts: 1824




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« Reply #1 on: August 21, 2014, 11:15:03 AM »

Go with resonant antenna.

There were a series of articles that tested a lot of configurations of mobile antennas
and the winner was....


As much mast(bottom) section as possible, load coil and put the hat at the top.
Taller is better.

For 20m and up the MFJ 17ft collapsible whip is all you need.  for 40m a coil at the
bottom of that will work fine.  When not in motion that is.

Any vertical used will need a ground or counterpoise which could be the body of the RV
if metal.

Its much like any mobile setup, Check the K0BG site http://www.k0bg.com/ for lots of stuff.

Allison
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