Cecil Moore wrote:

...
It actually seems to be a Zepp, rather than a J-Pole.
1/4WL feeding 1/2WL.

OK, we have had a similar discussion before, part of your text he

"In much the same way a Zepp or a J-Pole is not a 3/4WL
radiator even though they are 3/4WL long, a gamma match
on a base-fed 1/2WL vertical doesn't yield a 1/2WL
electrical radiator. For this reason, the length of a
gamma match should be considerably less than a wavelength.
A good rule of thumb is probably in the ballpark of less
than ~6% of a wavelength. Your idea seems to require about
16% of a wavelength."

I remember ...

Regards,
JS