How does a mismatch affect the radiation pattern?
tnx .....

It doesn't. I don't consider unbalanced, the same as mismatched,
to answer Cecils question. Feedline radiation can effect the
pattern due to a lack of balun, etc, but thats not the same thing as an
impedance mismatch. Also...Antenna "loading" is not the same as
antenna "matching". Many short verticals need both...
MK