I think the AM receiver input on car stereos is VERY VERY high
impedance; the antenna on AM is basically a voltage probe.

I don't know if the FM RX input is the same way, but the antenna is
just a stick of stainless steel.

The car stereo uses the single antenna for both bands as far as I
remember; a ferrite loop doesn't work in a car - - - you'd get fades
going around corners, etc. because of the directionality.

The spiral wrap is plastic. It does something to break up the vortices
that would usually be shed periodically off the antenna in the wind.


Dan