Gene Fuller wrote:

If I said that no balun is necessary then I apologize. I certainly did
not intend to say or imply such a thing. I do believe, however that a
single core balun would serve well if the antenna is balanced by design
and by its environment.

The question is how the single core balun performance degrades as the
antenna becomes less balanced through, for example, an asymmetrically
placed feedline. It seems difficult to analyze that problem, and
experimentation would be required.

I agree completely that there's no good way to analyze what will happen.
While you can model a 1:1 current balun with EZNEC or other NEC-based
programs, and an ideal transformer with NEC (or simply multiply reported
impedances with EZNEC), combining them for a model of a transforming
current balun, there's no way I know of to model even an ideal voltage
balun. And as I mentioned earlier, a real transformer is far, far from
ideal when terminated with the kinds of impedances you see in a real
antenna, particularly a multiband one.

You would indeed have to experiment. But it's easy to make quantitative
measurements of common mode current as I showed in the balun article. So
you can make good comparisons of one method over another for your
particular setup. I'd certainly be cautious of trying to extrapolate
what you found to other situations, though.

Roy Lewallen, W7EL