Just on the off chance does anyone know what these antennas have inside
them?

I could do with knowing and am not really in a position right now to
pull one apart and find out.

To me logic says they're just simple monopoles, and they definitely
don't present 50 Ohms across the frequency coverage in the specification
(25-1900MHz), which suggests to me that there isn't any matching network
in the base.

I've stuck one on my analyser, but of course that wouldn't show up any
matching network, though it does show the main resonance at 145MHz ;-)

Comments would be appreciated. :-)

--
73, Iain M0PCB/P