I completely agree! Back in the late 60's, I was Chief Engineer at WLRW- the first FM station in the state of Illinois to broadcast in stereo- and this was in Champaign-Urbana, not Chicago! The transmitter was an RCA BTF-10D which fed five Andrew "Vee" antennas and five Gates "Rings", giving us about 25 kW vertical and 25 kW horizontal. The majority of FM stations then used horizontal polarization, for reaching FM table radios that had line-cord antennas and component stereo systems. AM/FM car radios became an option around 1967, and WLRW was ready with a vertical component to better reach car radios.
I acknowledge that dual polarization is not the same as circular polarization, but it does accomplish what the station owner wanted back then: Full coverage of home and car/portable radios. I look forward to hearing about the changes that circular polarization can make to VHF repeater coverage. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Thursday, September 02, 2010 6:48 AM To: [email protected] Subject: [Repeater-Builder] Re: Circular polarization for VHF repeaters? FM broadcasting in the US is not changing to vertical polarization. There may be some old stations still running horizontal, and vertical is used in some situations (such as stations low in the band needing to be cross-polarized from a nearby channel 6 TV signal) but circular polarization is by far the preferred method. I've had FM stations running both, and have a firm impression that circular is indeed better for mobile reception. I may get the chance to convert some stations from vertical to c-pol when the rules are changed now that the conversion to HDTV has been made. I may have access to some papers on the subject - I'll check. I believe c-pol could be better for amateur VHF repeater-mobile operations in high-multipath areas. Steve
