Richard Clark wrote:

The difference between an infinitesimal antenna and a quarterwave
antenna is only 5%. However, to get the small antenna to resonate
brings far more opportunity for loss. 12-18" long is not likely to
bring you any advantage but carefree dreams unless you can strangle
the loss.

To clarify, that 5% is only for a lossless antenna. When the antenna
becomes very short, you also take a beating in conductor loss, since the
currents get enormous, so the antenna itself becomes inefficient. And of
course if the antenna depends on current through the ground, you take a
beating there for the same reason. So add conductor and possibly ground
loss to the inevitable loss in the matching network which must also deal
with high current and/or high voltage.

Roy Lewallen, W7EL