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Topband: Low Dipoles

To: topband <topband@contesting.com>
Subject: Topband: Low Dipoles
From: VE6WZ_Steve <ve6wz@shaw.ca>
Date: Fri, 11 Dec 2020 13:51:19 -0700
List-post: <mailto:topband@contesting.com>
I know this thread has gone on-and-on-and on, but I felt I needed to add to the 
discussion.

Regarding Roger G3YRO's 50 years of TB experience using a low dipole, I feel I 
need to support his observation from the DX side.

This winter season since August I have had 56 QSOs with the UK, and worked 21 
unique G callsigns. (Total this season is 775 EU QSOs)
The top 3 UK repeat QSOs are:

G3PQA 12 QSOs
G3YRO 10 QSOs
G4UFK 7 QSOs

The truth is, I have heard Roger many more times than we have QSO’d since he 
seems to have a challenging RX location.

Now, just working DX is not proof of good performance, BUT the FACT is Roger 
usually has a signal as good or better that the any of the other regular UK 
operators.
This would seem to agree with his RBN observations.  I am also aware that these 
“QSO totals” could be just a function of Rogers activity, but I have listened 
to Rogers signal **at the same time** as other UK and EU are QRV, and he is as 
good as the rest.

I love to build antennas and I do a lot of modelling.  I know exactly what the 
zenith and AZ plot a dipole at 50 feet looks like compared to a vertical 
antenna.  On paper it looks like the worst antenna possible for DX.  I am also 
aware of the concept that even though the dipole has a lot of energy radiated 
straight up, there is still some at lower angles. However, the gain from the 
low dipole compared to a vertical at these lower angles will still contradict 
what I copy from Roger.  Rogers signal “should” be much diminished compared to 
others in the UK (or anywhere in EU)  that are using vertically polarized 
radiators.

Here is a screen shot from 4NEC2 showing a dipole at 50 feet overlaid with a 
vertical over average ground. (2.1 dBi).
https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing
 
<https://drive.google.com/file/d/1Rdu94dVqrZQeYOa8KSJjM8MdSin63Pfj/view?usp=sharing>
At best Rogers dipole should be a great vertical iono-sound for testing the 
ionosphere!  At a 30 deg wave angle the vertical has an 8.5 dB advantage !  
That is a big number.

So, I have fair-good copy on Roger one Wednesday night :-) while he is CQing 
with his dipole, and then he switches to a newly installed vertical.  If indeed 
his signal bumped by 8.5 dB I think that would be pretty spectacular, and he 
would then be eclipsing the biggest signals out of EU.  His RBN skimmer spots 
would also jump by 8.5 dB !?. He would probably be spotted by double the 
skimmers in NA too.
In no way do I doubt what the modelling is showing us, but there is something 
else going on here.

This really is an interesting study.
Perhaps our propagation assumption about low-angle dominating is wrong?
As Roger said and I can attest, most of my copy and QSOs have NOT been at his 
or my SR or SS.

Roger, do you have a common mode choke on your dipole feed line?  If your feed 
line is radiating could it be emulating a vertical?

73, de steve ve6wz

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