HFU HF Underground
Technical Topics => Equipment => Topic started by: flexoman61 on November 09, 2015, 1640 UTC
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On 9/25/15 I posted a question about using a balun with a 43 meter band dipole
I had laid on top of my roof. http://www.hfunderground.com/board/index.php/topic,23588.0.html
There seemed to be a lot of interest so I figured I would post the results.
Thanks to everyone for the advice and suggestions.
I ended up going with Chris Smolinski's Sloping Folded Dipole. He wrote a detailed article
here on HFU with pics that was very helpful. http://hfunderground.com/blog/?p=84
The folded dipole went up at the far end of my backyard about 100' away from my house. This
puts it as far away from my house and the neighbor's houses as possible. The high end of the folded dipole is about 40' up
and the low end about 15' up, about a 30 degree angle.
I compared the folded dipole to my 100' longwire. The longwire has a 9:1 balun, coax feed line (about 30' RG58-U), braid grounded to 8' ground rod.
Up in the air about 15'. I use an antenna switch making it very easy for side by side comparison.
Now time for testing. Last night I tuned into Captain Morgan at 2250 UTC and then WMID at 2331 UTC.
A) During the Captain Morgan broadcast my longwire was giving me a very noisy S8, but with decent copy.
B) The sloping folded dipole gave me an S9+10 with almost no noise, very clear signal and the audio sounded real nice.
A) During WMID, the longwire gave me an S7 with a signal barely audible below noise floor.
B) The sloping folded dipole gave me a little better than an S9 with little noise, nice sig and audio.
I was very happy with the initial results. The Sloping Folded Dipole is very quiet. I have a high noise floor with the longwire.
Very low noise floor with the dipole. With the dipole being far away from the houses, up alot higher than the longwire, quad shield Rg6 coax
and the design of the sloping folded dipole, the RFI, QRM problems I have always had seem to be under control.
Of course more testing over time with different conditions is necessary, but I thought the initial results are worth
posting.
As far as the range of frequencies, a weather fax on 6338.6 kHz had a much stronger sig on dipole than the longwire.
The 40meter ham band signal was much stronger on dipole than the longwire, and much less noise. I plan on testing the frequency range a lot more.
A quick tune in of WWV at 15 MHz at 1630z, the dipole gave me a little less signal (S7) compared to longwire (S9) but the dipole is MUCH
quieter.
I am going to have some fun with this new antenna.
I may let my wife hang laundry on the longwire antenna!
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Sig to noise ratio has always been important with me
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I've had very good results with any sort of loop antenna (which I consider the folded dipole to be a subset of, by loop I mean there is a continuous DC path through the entire antenna) being low noise. It really does seem to make a difference.
Congrats on the new antenna, it's always great when they work better than the old one ;D
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Thanks for the update and details, flexoman.
Sounds great.