The fact that we get widely varying reports about the performance of the
T2FD antenna suggests that an equally-long dipole would give good results
across the frequency spectrum if used with an antenna tuner. What the
T2FD really buys you is the ability to avoid an antenna tuner.

There is an amateur antenna out there consisting of an 80-meter dipole
(I mean one that is a half wave at 80 meters, not one physically 80 meters
long) fed with about 100 feet of 450 ohm ladder line. It turns out that
100 feet of line is within about 10% of the idea length to match the
antenna to 50 ohms on all amateur bands. One design of this antenna uses
a tuner to correct for the mismatch, while another uses various lengths
of 450 ohm line added to the feedline to achieve a match.
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jhhaynes at earthlink dot net