WN3J wrote:
>It wasn't until car
>radios with vertical whip antennas started to gain popularity did vertical
>polarization start to become important, and CP resulted as a solution to
>satisfy listeners using either horizontal or vertical antennas, while
>improving multipath performance as a side-benefit. Of course this also
>meant that broadcasters needed 2X the transmitter power, or 2X the number of
>antenna bays, to achieve the same amount of ERP, to convert from H to CP.
Actually, as I wrote, the opposite is true. CP give MORE multipath than linear
polarization. CP gives higher average signal strength but a lower _quality_
signal. This is especially hard on an FM-stereo signal, which is even more
susceptable to mulitpath distortion than an FM-mono signal.
So there's the trade: more average signal strength but more mulipath.
(Did you know that when various systems for broadcasting FM-stereo were
evaluated, the system which used FM for the stereo subcarrier was rejected due
to greater upset by multipath than the AM subcarrier system that was ultimately
chosen.)
I think that CP would work well on an amateur radio repeater. The increased
average signal strength (there's more uniformity of signal strength as well in
a moving vehicle).
--John
--John
