chuck wrote:
If the antenna system can be satisfactorily matched to the transmitter
output impedance, it would seem to matter little whether the feed line
currents are balanced, or, if they are not, by how much.

If there are no obvious common mode currents causing problems in the
shack, then of what consequence would an imbalance be, other than to
modify the radiation pattern, perhaps even beneficially?

You have to remember that the common mode feedline current doesn't stop
at the rig. It continues to the Earth by whatever means are available.
So your house wiring, appliance cords, and other odd conductors often
become part of your antenna system. These aren't likely to be very
efficient radiators. People often go to a lot of trouble to put their
antennas high and in the clear. That doesn't make much sense if you're
going to have your house do a good part of the radiating.

But you can still talk to lots of stations even if some of your
radiating is being done by your feedline and house wiring. And that's
enough for a lot of folks.

Roy Lewallen, W7EL