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? The web article for which I gave a link was from Europe and involved IBC Israel & BBC UK tests and their conclusion was similar on Vertical Polarization. Many lack of coverage issues I've seen with extremely high sites is due to the use of high gain antennas with little or no down tilt. I have seen issues like this resolved by simply using a lower gain, say going from 10db gain down to 7 dB gain and applying 4 - 6 degrees of down tilt. Lowering the gain widens the beam and addition of down tilt puts the major part of the RF signal closer in and that improves coverage but it still puts a signal out to the RF horizon.
Peter On Thu, Sep 2, 2010 at 1:47 AM, JOHN MACKEY <jmac...@usa.net> wrote: > > > FM broadcast is NOT changing to vertical polarity! > > Most stations today are going on the air with either circular polarity or > cross polarity (consisting of signal in BOTH the vertical and horizontal > poles) > > With FCC licensing today, a FM station licensed for 10KW can have 10 KW in > the > vertical plane and 10 kW in the horizontal plane. So there would be no > reason > to only have the power in one plane. > > In the last 3 years, I have built 2 FM stations. Both used circular or > cross > polarity. > > > ------ Original Message ------ > Received: Wed, 01 Sep 2010 10:32:51 PM PDT > From: petedcur...@gmail.com <petedcurtis%40gmail.com> > To: Repeater-Builder > <Repeater-Builder@yahoogroups.com<Repeater-Builder%40yahoogroups.com> > > > Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF > repeaters? > > > Hi, > > I remembered circular polarization was used for FM broadcast due to FM > car > > radios, but when I looked it up I found out some interesting facts, see > the > > link below, > > > > > > https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_content&view=article&id=57&Itemid=134 > > > > > < > https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_content&view=article&id=57&Itemid=134 > >Interesting > > white paper on FM Broadcast and why they had historically had circular > > polarization and why they are now changing to vertical polarization. > > > > Peter > > > > On Thu, Sep 2, 2010 at 1:22 AM, burkleoj > > <joeburk...@hotmail.com<joeburkleo%40hotmail.com>> > wrote: > > > > > > > > > > > Gary, > > > I am in Southern Oregon and I understand exactly what you are > experiencing. > > > We have very similar problems down here with our club's repeater. I > have > > > often talked about and even done some serious looking at remodeling a > set > of > > > broadcast loops and harness for 2 Meters. > > > > > > I know there was a southern California repeater back in the 70's that > used > > > circular polarization with excellent results. They were able to provide > much > > > better coverage in their main service area, but did loose some long > distance > > > coverage outside their main coverage area. > > > > > > We have had the best success by using a lower gain antenna. We have > been > > > using the Telewave broadband two loop antennas with 2 - 4 degrees of > > > downtilt, for both our 2 Meter and 440 MHz repeaters. I have found much > > > better close in (0-30 Miles) coverage, less muti-path, and they cost > quite > a > > > bit less than a Super Stationmaster. > > > > > > Good Luck and keep us posted with what you find for results. > > > > > > Joe - WA7JAW > > > > > > > > > --- In > Repeater-Builder@yahoogroups.com <Repeater-Builder%40yahoogroups.com> > <Repeater-Builder%40yahoogroups.com>, > > > > "Gary - K7EK" <gary.k...@...> wrote: > > > > > > > > > > > > Greetings, > > > > > > > > I am in a particularly sticky situation with one of my two meter > > > repeaters in Lakewood, WA (Tacoma). I have generally great coverage, > however > > > there is a very annoying problem with multipath and raspy signals in a > large > > > portion of my coverage area. Since the Puget Sound area of Western > > > Washington is very hilly and mountainous, multipath is very damaging to > all > > > forms of VHF communication. > > > > > > > > > > > > > >
