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HF 1/2 Wave Dipoles

R

Rudes

Member
Dec 20, 2008
52
0
16
Hey Guys,
I want to build a dipole antenna for 10 - 20 meters that I'll be using with a tuner. Out of these 2 options which do you think would work best? Using 1/2" metal conduit and making a 30ft vertical (15ft each side) or running wire horizontally through my hedges that are 10ft above ground? I can go up to 25 ft on each leg of the wire dipole. Thanks...
 

Either would probably work as well as the other. I would rather do the one laying on that 10 foot tall hedge. I can make wire antennas easily, the standing up by it's self verticals are harder for me to do.
Combining a 10 meter and 20 meter antenna into one is also easier to do with wire (for me). Making just one antenna work on both bands, without some traps isn't going to work at all well.
Have fun.
- 'Doc
 
If you can get the 20 meter dipole up at 25' as a flat top, add the 10m dipole to it as an inverted V and feed both with one feedline. Then you have 2 resonant dipoles, no tuner required. That would work the best from the standpoint of performance for the dipoles.

You could also try a 20 meter vertical if you can lay some ground radials and put the 10m dipole up as a flat top. I have a homebrew 20m vertical that works great with about 40 radials I think. You don't need nearly that many but I had the time and wire. If you lay the radials in the spring, in a couple of weeks they get caught up in the grass and thatch and you'll never know they are there.
 
"Do you feel this would out-perform the horizontal wire?"

Half the time, maybe. The other half of the time, maybe not. It deals with polarization not any 'gain' since they are both 1/2 wave lengths.
- 'Doc
 
Thanks for the feedback guys. But doesn't the horizontal need to be high off the ground? It would only be 10 ft up in the hedges and I would be working 10 - 20 meters. Is that OK? I just want a center feed single wire.
 
Rudes said:
Thanks for the feedback guys. But doesn't the horizontal need to be high off the ground?
"Should be" at least half a wavelength.


It would only be 10 ft up in the hedges and I would be working 10 - 20 meters. Is that OK? I just want a center feed single wire.
Click to expand...

Best thing: try it out - experiment - see how it works and then try to improve it.
 
Would it work better if it were higher? Probably, but who says it won't work well if it isn't as high as it "should" be? As already said, try it and see. You might be surprised.
- 'Doc
 
Antron 99 vs Wire Dipole

I strung a 33' long dipole out today and was checking its performance on 10-20 meters. I compared it with my Antron 99 and the Antron had a full 4db receive gain on 15 meters over the wire dipole tuned with an Supermatch antenna tuner! If the Antron is tuned for 11 how the heck can that be?
 
Many different factors as to why the A 99 received better than the wire.

Dx signals arrive at different angles, if your dipole was horizontal, the A 99 vertical, that would be 18 to 24 db of difference in receive signal strength due to polarization of received signal.

Experiment with different type of antennas, verticals or dipoles, or even given that you may like to use a tuner try a loop.

Try many and different ones and then see for yourself which ones work the best for you..

I have been experimenting for years with antennas and have my favorites, some work better than others.

It all depends on what you as the operator want to do. Rag chew? Then look at NVIS antennas.

Chase DX? Then look at verticals for low angle of radiation, which is a good thing, but not always, depends on where the DX signal is arriving from.

So many variables in antennas and installations.

That is like asking why does my 40 meter dipole out perform my tri bander on 15 meters into South America, yet my tri bander outperforms my wire into Asia?

Different antennas do different things, even on the same frequency.

As stated before experiment, then you will be able to decide which antenna best suits your operating needs.

Most of all have fun.
 
I would guess that the difference in polarity would be a big factor. Another is that neither antenna would be 'tuned' for 15 meters so I wouldn't expect 'good' reception on that band. Something else to think about is that 'A99' already has a matching network in addition to that tuner and the combination of the two can mean some odd or 'different' behavior. The wire antenna was limited to what only that tuner could do.
None of this means that there's anything 'wrong' with either antenna.
- 'Doc
 
Rudes said:
I strung a 33' long dipole out today and was checking its performance on 10-20 meters. I compared it with my Antron 99 and the Antron had a full 4db receive gain on 15 meters over the wire dipole tuned with an Supermatch antenna tuner! If the Antron is tuned for 11 how the heck can that be?
Click to expand...

You didn't tell how high either are mounted so I'll take a guess. Could be because the vertical is closer to a half wave at 15m and mounted higher than the 33ft dipole. 33' wouldn't even be close to resonance on 15m. So your radio sees a perfect match between itself and the tuner. On the other side of the tuner it's a different story. Also what Doc said about polarity. 10 minutes later that dipole may have had thegreater signal as propagation bounces the signals around.

Dipoles work optimally well at the freq they are cut for or somewhatwell at each odd harmonic. Anywhere else it's a crap shoot.
 

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