<<antennas embedded in epoxy/glass is
they can be very lossy compared with free space wire antennas>>
The loss is very frequency dependent and special materials are required
for instance for radomes at microwave frequencies. Even then rain water
with its large dielectric constant and possibly conductivity will have an
effect. Luckily it is usually swept away by the slipstream (unless it
freezes in which case you have more problems than communincations !).
With an epoxy aeroplane I can see little point in poking the antenna
through the fuselage and then covering it with another epoxy cover as was
done with the G-EURO gps antenna.
gemin
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