You might be right Bob. I don't know what Conor expected with his shorter mast length ideas, but if I add a Feed Line to these models, it would simply provide another conductor path, of unknown length, for CMC to flow on the model.
The models I made only tried to demonstrated what an A99. with these short masts lengths might look like, if there were no CMC flowing on such a system, and instead had a coaxial choke or other type...that worked as intended.
I could also isolate (ISO) the mast from the antenna at the top an inch or two and see similar results. So, ISO by itself has limitations also.
I'm sorry I mislead you guys with these models. IMO and not to be confused, I don't think they are what they seem...surely when compared to a Real Earth antenna installation.
Personally, I don't think this idea of shortened mast is likely to produce any advantages over a grounded type installation and it maybe just be a convenience.
I don't like the idea of installing CB size antennas on or attached to my home, but I learned that the hard way. And down the road I paid big money to fix those problems.
I also see CMC increasing a little on the masts in the both models I presented with shortened masts, when compared to the full length mast model. In that case the simulated choke did not work the same with all 3 models and maybe that should not be surprising.