That's what I always thought, but according to one of the links you provided
http://www.signalengineering.com/ult..._antennas.html
it's done to even out the skew in the omnidirectional pattern caused by the
asymmetric vehicle ground plane.
For the 18-wheelers with side mirror mounted antennas it might also help to
eliminate the shielding effect of the large trailer body if only one antenna
was used.

A real simple measurement would be to walk a circle around the truck with a
field strength meter and see what you've got.

But for anything else than an 18 wheeler I think it'd be a total waste. But
then again with CBers it's not just about how you sound but about how you
*look* !

John




wrote in message
...
will two cb antennas make a big difference my friend is going to
put two mobile antennas on his truck i told him it will more
trouble than it is worth. because to set the swr will be a pain
thanks and 73s

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