"Karl Uppiano" wrote in message
news:uqHuf.1768$Pe6.76@trnddc08...

"David Tweed" wrote in message
...
mc wrote:
I thought they were going to vertical polarization because of car
radios. I'm wondering where I read that, and whether it's true.

I'm pretty sure that commercial VHF services like FM radio and TV
prefer horizontal polarization because of fewer problems with
absorption and/or diffraction from vertical objects such as trees
and poles.

Also, most customers for these services have fixed antennas, and
can do horizontal just as easily as vertical. FM radio in the car
is an exception, as you note, but most cars these days either have
a horizontal dipole in the window glass somewhere, or a whip that
has a significant amount of tilt.

On the other hand, VHF services that are intended *primarily*
for mobile customers (public service bands, etc.) use vertical
polarization because the car antennas really want to be vertical
whips for mechanical simplicity.

-- Dave Tweed

Almost all commercial FM stations in the US are circularly polarized (1/2
power vertical; 1/2 power horizontal, 90 degrees out of phase). That
covers both types of antennas, and if you have a CP receiving antenna, you
can dramatically reduce multipath if it is oriented toward the
transmitter.
Karl -

You beat me to that answer, which is correct.
I installed a set of 2 horizontal staked loops for one college broadcast
station (they had no desire for mobile users) and the antenna was free from
a commercial station that upgraded to CP as pointed out by Karl).

gb