Owen Duffy wrote:
K7ITM wrote in news:1a1dd526-f947-482c-84d9-dd789a6b8f75
@e19g2000prn.googlegroups.com:
...
I don't think it guarantees it.

That is the issue with the Zepp. Radiation is the result of current flowing
in the 'flat top' and the common mode component of current flowing in the
not-standardised feed line.

If the feedline was say a quarter wave vertical section (as is often
depicted) with the common mode point at the bottom effectively grounded
(not usually clearly described), you have a three quarter wave L fed one
quarter wave from the end. If the common mode point referred to above was
effectively isolated from ground, you have a different antenna, different
boundary conditions to satisfy. Still, the are all Zepps to us!

Owen

Exactly. People tend to look at the flat top as the "antenna" and the
twinlead as the "feedline". In actuality, the "feedline" is an essential
part of the antenna, and any changes in it modify the radiation
characteristics as well as the impedance. The same binary thinking often
misleadingly separates "antenna" from "ground".

Roy Lewallen, W7EL