Marconi, did you ever do this test?
73
Jeff
Yes Jeff, I did install my Francis Wheeler Dealer in the top of my Marconi with 4 slanted down 102" radials.
My notes, however, don't show that I did any specific comparison work to a similar install with 102" ss radiator as I promised. Gettin' old.
I do have some analyzer and SWR bandwidth reports that I recorded, but the antenna heights were not the same and there is no indication on which mount the antennas were installed on. So, it looks like I wasn't thinking about such a consideration when I finally got around to doing testing with the Francis some months later.
The reports do, however, show that the Francis, at 31' high, was resonant about 18 channels lower in frequency than the 102" whip at 52' feet. The height for the Francis was about 20' lower as noted. Maybe this height difference made or contributed to this lowering in frequency, but I'm not sure.
I also noticed that the bandwidth for the Francis was actually less that the 102" whip as well, and I am surprised at both results. I would have though things to be the very opposite from my previous thinking back then.
Another thing I noticed in looking over this old record is that the Francis and the 102" whip manifested about the same mismatch on my analyzer, and again that surprises me. I would think the Francis might show a better match for CB. That said however, it is my opinion that the modest matching differences we might expect to see among such CB antennas will not exhibit enough difference in performance for us to tell just using our radios.
While all this testing was going on back then, I was also doing signal reports, but I can't find any notations on the Marconi reports telling me which radiator I was using, so another dead end.
IMO, this style of antenna is very well balanced and the radial cone below the feed point appears to help improve feed line decoupling. This said however,
modeling of these type antennas does show that specific heights of the mast and the length of the feed line plays an important role in such destructive radiation, so maybe we can't fully attribute all of this affect to the radial cone design in this particular antenna.
I can't prove it, but these symmetrical features in combination with a 1/2 wave radiator that shows minimal feed line and mast currents could be what provides the very good signal reports I typically see when comparing it against my other antennas.
