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 <[email protected]> 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 <[email protected] > <mailto:[email protected]>> 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
