glass fm antenna

I saw the following fiber glass antenna.
It is with built in 30db pre amplifier.
I want to know how can they design such small with fibre glass.
what is the principle of fiber glass antenna design?

Since it is an antenna for FM/AM most
likely is for reception only. In which case
most of them use ferrite posibble polarized
to decrease the size of the antenna.

Nice interesting topic!
But where can we get more info about how they design.