>It looks like the FCC rules give you extra power when opting for dual >polarization. Doesn't mean the circular antenna contributes to extra >coverage, in fact it looks like the extra RF power allowed for the two >polarities is giving you more coverage?
That's a confusing point, I know. Every circularly-polarized FM station I've seen (and that's a lot of them) use an antenna design that handles the phasing and "time-delay" to create the circularly-polarized signal. It is generally not done with separate horizontal and vertical antennas, another transmitter and phasing in the transmitter building, or anything like that. Think of it this way - a circularly-polarized signal is "spinning" as the signal goes thru each RF cycle. At any given moment it is rushing from vertical thru various diagonal polarizations to horizontal and back around again. The license reference to H and V powers (regarding c-pol station) is intended to say how much ERP should some out when the signal is V and how much when it is H. It is possible to make the two components different, resulting in elliptical polarization rather than circular. A VHF repeater could use the same antenna concepts (usually crossed dipoles with a phasing harness) to produce circular polarization. Have a look at circularly-polarized satellite antenna designs. Steve WD8DAS sbjohns...@aol.com http://www.wd8das.net/ -------------------------------------------------------------------- Radio is your best entertainment value. --------------------------------------------------------------------
