From URL:
http://www.astronantennas.com/polarization.html
In the early days of FM radio in the 88-108 MHz spectrum, the radio stations
broadcasted horizontal polarization. However, in the 1960's, FM radios
became popular in automobiles which used vertical polarized receiving whip
antennas. As a result, the FCC modified Part 73 of the rules and
regulations to allow FM stations to broadcast RHC or elliptical polarization
to improve reception to vertical receiving antennas as long as the
horizontal component was dominant.
--
Caveat Lector


Someone correct me, but don't FM stations transmit both vertical and
horizontal?

I hope this helps.


--
73 for now
Buck
N4PGW