Setting aside the mistaken belief that even licensees of several years'
standing
have that a short antenna will radiate all the power that is fed to it, even
long
antennae do not do that!

Consider the terminated and very-directional Rhombic with legs that are
several
wavelengths long; the reason for the termination is to absorb the power that
does not
get radiated and to prevent it being reflected and so making the Rhombic
bi-directional
instead of uni-directional..

Also, consider the following, if shorter (than the Rhombic) antennae radiate
all the
power fed to them, there would be no advantage to extending the length of
any antenna
because the shorter bit would have radiated all the power, and there'd be
nothing left
for the longer bit to radiate.

As it is short (and unterminated) antennae only radiate a small proportion
of the power that
is fed to them, and that which is not radiated is refelcted back to the feed
point considerably
out-of-phase with the incident power and so presenting a very reactive
impedance. (Yes, OK,
on the way back from the reflection, a bit more might get radiated, but I
suspect that the
out-of-phase wave affects the EM fields thereby reducing the radiative
capability)