35, I tend to agree that including the mast in our models is important, but my point was to consider...what if a modest change in height were enough to mitigate the CMC issue. Or, like Shockwave correctly mentioned...it is actually coax length instead of height above Earth. It would seem to me this idea would be pretty simple to duplicate if someone has an antenna that produces some TVI that is easy to detect. Just change the length of your feed line 4'-9' and see if there is some change in the TVI. It would not be exactly the same as I noted with my models, but it might show something. I don't have an antenna up right now that I could check or I would add a short jumper to the transmitter end and see what happens.
I just now tried readings on my stationary field strength meter with a 14' coaxial antenna, and when adding 4 feed of coax to my Starduster shows a 100% increase in FS indicated vs. the regular feed line. So I know this 4' foot jumper adds field strength below the antenna, and I assume it is from the feed line/mast which is right outside the window of my shack. However the old SD'r is very good, and does not produce any detectable TVI that I can hear on my PC speakers. IMO, most vertical antennas make CMC, but depending on the magnitude the issue might not even be noticeable.
Regarding your gamma match comment. IMO anything we can do to place the feed point in a more symmetrical environment has to be technically more better.
However, with such comments I consider to ask...how much difference does it make? Is this technical difference enough that we can tell just operating our radios? If not, then it probably doesn't matter much. I haven't tested this idea, but I do have a HyGain Long John with a hairpin match and isolated driven element, and I thought my 4 element yagi with a gamma was better.
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I did not exactly experiment with the idea, and I did not compare these two, because at the time I didn't realize the big controversy, so have you some experiences you can post?
