Roy, W7EL wrote:
"This is true only if no effort has been made to match the antenna to
the transmitter."

It is true with every transmitter which occupies more than zero
bandwidth. Reactance is zero at one point in the frequency spectrum.
Off-resonance, an antenna system accepts less current than it does
exactly on resonance. But, the difference is usually less than 1 db.

I wrote that if the antenna is operated off-resonance (excited by a
frequency other than its resonant frequency) it works but with less
vigor etc.

If the antenna`s power factor has been externally corrected for some
frequency other than its natural resonant frequency, then it is
resonanat at a new frequency. Its vigor will not be subdued by inherent
reactance at the new resonant frequency.

When I said an antenna operated off-resonance works with less vigor, I
tried for a statement true with a solid rod without connections and in
free-space, a receiving antenna, and a transmitting antenna, all
operated at a frequency other than their resonant frequencies. All are
transmitting antennas because they all radiate when excited, no matter
how the excitation is delivered.

I think I succeeded in saying it correctly but failed in saying it well
if it was misunderstood.

Best regards, Richard Harrison, KB5WZI