"Steve W." wrote in message
...
Jim, you are correct. The antenna is the vertical element and the
vehicle is the ground plane. That is why the coax is grounded at both
ends and one small open area causes noise. Some of the new antennas are
hidden in the glass with the defroster, or just in the glass around the
edge. Then there are diversity antennas that have 4 antennas embedded in
the bumper covers or other plastic trim. Those are connected to a box
that senses the different signal levels and uses the strongest. Anyone
who thinks otherwise doesn't know how a radio signal functions.

--
Steve Williams

Steve

I'm surprized that you state that anyome who doesnt accept that the car is
a ground plane doesnt know how radio signals function.. I assume that you
agree that the impinging radio signal is vertically polarized. I asume you
also are considering cars that are only about 1 or 2 electrical degrees
high. Can a conductor that small (short) be considered a "Ground Plane"??

I didnt realize that cars had been equipped with an AM antenna systems
that select one or more of several probes in the trim and/or bumpers. That
seems to be unnecessary complexity, but it must provide some improvement.
Where can I find more information on the car that has the 4 embeded
antennas?

Jerry