I would agree that lower gain antennas can make a big difference in some instances. Higher gain mean more nulls.
Chuck WB2EDV ----- Original Message ----- From: [email protected] To: Repeater-Builder Sent: Thursday, September 02, 2010 10:38 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? 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 <[email protected]> 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: [email protected] To: Repeater-Builder <[email protected]> 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 <[email protected]> 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 [email protected]<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. > > > > > > > ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3108 - Release Date: 09/02/10 02:34:00
