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
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband
> <http://www.contesting.com/_topband> - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|