I want to put an eight wire vertical cage around a one hundred twenty
foot steel support for 80 meters. I can center feed the cage with
open wire line, which I assume will be more efficient than feeding the
steel at the bottom. The cage will not be in contact with the ground
or the tower. My thought is that the wires will make a better
radiator than the steel, but I have no idea what the steel "core" will
do to the efficiency of the antenna. I have had no success in
modelling this antenna.

So my question is will the center fed, ungrounded cage dipole provide
any real advantage over feeding the tower at the bottom?

Thanks.

Dave