[Antennas] Antenna Design Help Please

[Harvey&Bessie]

Kevin,
    There should be very little, if any difference in performance in the
antenna you describe, whether made from 300 (tv) twin lead or its big
brother 450-ohm ladder line. Such an antenna, of course is essentially a
vertical radiator and as such needs a good ground plane to function
effectively. One "counterpoise" wire will help, of course, but it won't
do the entire job (of providing a ground plane, that is.).
    I have seen much ado about shorting the two conductors of a folded
dipole or monopole some distance from the end(s). But my view of that is
that it does not change anything since both conductors of a folded
antenna of that sort are at the same potential. Connecting two points of
a circuit (of any kind) together has no effect on the network! As a
matter of fact with a folded antenna, dipole or monopole, the ends can
be left open or connected together and it will not effect the
performance.
Harvey/W4TG