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Re: Topband: Low Dipoles

To: Dave Cuthbert <telegrapher9@gmail.com>
Subject: Re: Topband: Low Dipoles
From: VE6WZ_Steve <ve6wz@shaw.ca>
Date: Sat, 12 Dec 2020 10:50:26 -0700
List-post: <mailto:topband@contesting.com>
Hi Dave,
Indeed you are correct. Sorry about that.
However, broadside I still see a 4.5 dB advantage to the vertical, but of 
course this can vary wildly up OR down depending on ground quality in the near 
field for efficiency and the far-field of the vertical.
A new plot showing both Zenith, and AZ plot at 30 deg wave angle:
https://drive.google.com/file/d/1OaQI0-2hLUjaG3cyoqp27d6qVURRMixC/view?usp=sharing
 
<https://drive.google.com/file/d/1OaQI0-2hLUjaG3cyoqp27d6qVURRMixC/view?usp=sharing>

Steve, ve6wz


> On Dec 11, 2020, at 11:07 PM, Dave Cuthbert <telegrapher9@gmail.com> wrote:
> 
> The radiation pattern plot shows the dipole end on. Rotate azimuth 90 degrees 
> and the two antennas show the same gain at 30 deg elevation. 
> 
>     Dave KH6AQ
> 
> On Fri, Dec 11, 2020 at 10:51 AM VE6WZ_Steve <ve6wz@shaw.ca 
> <mailto:ve6wz@shaw.ca>> wrote:
> 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>
>  
> <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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