John wrote:
Many thanks for your time Gents, The antennas were intended for outdoor use
and constant handling. being encased in hard plastic obviously enhances
those functions. My experience has been at the other end of the spectrum so
to speak and I (incorrectly) assumed an antenna picks up an electrical
signal. Putting a layer of insulating plastic on it seemed contradictory. If
antenna is detecting magnetic signals obviously a different story.
When I mentioned impedance I mislead you. Wasnt referring to antenna
impedance but the impedance looking back form the recieving antenna to the
signal source ( thats what us old analogue designers do, Norton/Thevenin
equivalent circuits etc !!!!) and the effect on that a layer of plastic
has.
Your combined efforts have answered a lot of my questions, thanks for your
time.

Unfortunately the clueless idiot from Poland has woken up and is
making his outdated claims again...

What you should know is (and apparently have realized by now) that
the antenna impedance is not an impedance between its elements and
the surrounding air, but a "radiation impedance" that results from
the antenna emitting an electromagnetic field. This field traverses
plastic, a vacuum, air etc without problem so it does not matter if
you coat the elements.