[Repeater-Builder] Re: Circular polarization for VHF repeaters?
WN3A wrote: That's pretty much correct, but there are many stations that have a vertical component added that isn't necessarily part of a circularly-polarized array. The discussion was about circularly-polarized antenna arrays, so my comments were completely correct - not pretty much. -grin- In my experience, cross-polarized antenna systems (those with simultaneous in-phase vertical and horizontal components) can make multipath cancellations worse, not better. Depends to some degree on the nature of the objects causing the reflections, I'm sure, and whether or not the two antenna components are fed in a controlled way or just excited by being in the field of the main element. Circular does not have this drawback, as at any given instant it is just one polarization. Steve WD8DAS
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
At 9/5/2010 08:23, you wrote: In my experience, cross-polarized antenna systems (those with simultaneous in-phase vertical and horizontal components) Isn't that just diagonal polarization? You can't have multiple linear polarization orientations; that's the whole point of circular polarization. Bob NO6B
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
It looks like the FCC rules give you extra power when opting for dual polarization. No, they don't give you extra power. For commercial stations, horizontal polarization is the standard. You can supplement it with vertical, either as cross-polarized linear, or as elliptial/circular, but that Vpol component's ERP can't exceed the Hpol ERP. For non-commercial stations in the reserved band (i.e. below 92 MHz) within the affected area of a channel 6 station, there are many cases where they are authorized for more Vpol than Hpol to protect channel 6 (which is presumed to always be horizontally polarized). The only extra power you get is additional transmitter power output (TPO) due to the reduced antenna gain (assuming the number of bays remains the same, and the same bay spacing) when you go from horizontal polarizaton to mixed polarity. 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. That's pretty much correct, but there are many stations that have a vertical component added that isn't necessarily part of a circularly-polarized array. The vertical may be added as a separate radiator, but not phased with the Hpol radiators to yield circular, so you just have two non-coherent linear polarizations. Or a single linear radiator may be tilted to give slant polarization, which the FCC will accept as having both an Hpol and Vpol component, with the ratio being a function of the tilt angle. 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. They can be different, and yet not be elliptical. If they aren't phased together to yield a coherent rotation at all azimuthal angles, it's just random cross-polarization, not elliptical. 99% of the current topic was covered a year or so ago on this list - might want to revisit the archives. For those thinking about building Cpol bays, I'd suggest starting out with something simple like a ring-stub. Easy to make with a tubing bender (or Armstrong method), feed with a gamma, DC-ground at the mounting bracket at the rear of the bay, decent pattern circularity (but not great axial ratio symmetry), cheap and easy way to start. For those not familiar, a ring stub bay looks like this (I don't recommend OMB, it's just a decent picture of a very basic ring stub bay): http://www.omb.com/en/index.php?option=contenttask=viewid=78Itemid=38 Ring stubs are sometimes also called cycloids (albeit sometimes erroneously), often built with a balanced feed. You can try Googling cycloid, ring stub FM antenna, etc. for more pics and design ideas or email direct. --- Jeff WN3A
[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? 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.
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
Gary, Once you get it figured out, PLEASE write up an article for Repeater-Builder for the rest of us!! Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Gary - K7EK Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Fri, 3 Sep 2010, Mark wrote: Once you get it figured out, PLEASE write up an article for Repeater-Builder for the rest of us!! Make an X with dipole elements, and connect the feed harness to one side, and connect the left and right sides together with 1/4-wavelength of coax, wire, or coat-hanger. The antenna elements should be on opposite sides of the mast. Something about this tells me that the stack should have the next section up rotated 90-degrees around vertical to eliminate nulls. If you take that and try to build it all around the same point, it starts looking like an imploded Lindenblad. -- Kris Kirby, KE4AHR Disinformation Analyst
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Fri, 3 Sep 2010, Kris Kirby wrote: Once you get it figured out, PLEASE write up an article for Repeater-Builder for the rest of us!! Make an X with dipole elements, and connect the feed harness to one side, and connect the left and right sides together with 1/4-wavelength of coax, wire, or coat-hanger. The antenna elements should be on opposite sides of the mast. Something about this tells me that the stack should have the next section up rotated 90-degrees around vertical to eliminate nulls. If you take that and try to build it all around the same point, it starts looking like an imploded Lindenblad. I could go further to say that it should be possible to do this with two DB-224 clones, the ones that hold the elements to the pipes with hose-clamps. Connect up all the feed harnesses as you normally would and connect the two by a -90 degree hybrid, or a 0-degree (in-phase) Wilkinson divider with a -90 degree section (1/4-wavelength) of coax on one leg, so that one antenna is fed -90 degrees (1/4-wavelength) from the other. Pasternak's article makes mention that these antennas are difficult to match. Things being as critical as they are, I would recommend tuning for minimum VSWR, since the receivers are hardly ever 50-ohms. This antenna may lend itself better to a split-antenna system without much separation between the circular antenna and the vertical antenna -- simply to avoid detuning the receiver duplexers if the antenna loading situation changes due to ice or other effects. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
FM Broadcast started out Horizontally polarized. Circular polarization was later authorized under 2 stipulations. The vertical plane power can not exceed the horizontal power ERP, and the horizontal plane ERP is used for the stations ERP. So a station with a horizontal antenna can effectively double the ERP by switching to a circular antenna, of course it takes 2 CP antennas to equal one horizontal antenna. On the receive side of things, Horizontal is usually used in homes and Vertical or CP on cars. CP also helps quite a bit with mobile flutter.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
HI to all, I guess that I do not have much to contribute on this thread but to me it is very interesting reading. Gary has my sympathy, his problem is duplicated here. Much of my repeater work relates to a low power portable repeater on 141 MHz. We live near a medium sized mountain range which has plenty of deer and wild pigs. Hunters go looking for them and perhaps get lost, or fall and break a leg. Also, there are recreational trampers who just get lost . Several times a year we have to go find, and rescue them. The last time was two days ago at 6.30 am. For once, it was not raining! Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. Gordon ZL1KL Tauranga N.Z.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Antennas might be a bit of a trick for portables on 10m, and a repeater might have to be crossband, but worth a shot. 73, Paul, AE4KR - Original Message - From: Gordon Cooper To: Repeater-Builder@yahoogroups.com Sent: Thursday, September 02, 2010 1:51 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
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: petedcur...@gmail.com 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 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 To: Repeater-Builder Repeater-Builder@yahoogroups.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_contentview=articleid=57Itemid=134 https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_contentview=articleid=57Itemid=134Interesting 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 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.comRepeater-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
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
There is one local UHF group that has a back-to-back 6m repeater just for range extension. The Scom 7330 makes the parallel/separate link on/off mode real easy (and for up to 3 ports). At 02:10 AM 09/02/10, you wrote: Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Antennas might be a bit of a trick for portables on 10m, and a repeater might have to be crossband, but worth a shot. 73, Paul, AE4KR - Original Message - From: mailto:zl...@nzart.org.nzGordon Cooper To: mailto:Repeater-Builder@yahoogroups.comRepeater-Builder@yahoogroups.com Sent: Thursday, September 02, 2010 1:51 AM Subject: Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters? Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3107 - Release Date: 09/01/10 11:34:00
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Thu, 2 Sep 2010, Gordon Cooper wrote: I guess that I do not have much to contribute on this thread but to me it is very interesting reading. Gary has my sympathy, his problem is duplicated here. Much of my repeater work relates to a low power portable repeater on 141 MHz. We live near a medium sized mountain range which has plenty of deer and wild pigs. Hunters go looking for them and perhaps get lost, or fall and break a leg. Also, there are recreational trampers who just get lost . Several times a year we have to go find, and rescue them. The last time was two days ago at 6.30 am. For once, it was not raining! Our repeater runs 5 watts output, needs to run three or four days off a gelcell, and most importantly has to fit into a backpack to be carried to a convenient hilltop. Fortunately, the split is 3 MHz so that the duplexer is of a reasonable size. You need lower power output and a further split and a big battery. Even running a repeater at five watts with commercial handhelds out in the field (each of which have a battery that will make it for eight hours), you're going to need somewhere around a 33Ah battery, which weighs 25 lbs. The problem is getting reasonable coverage. Sure the search areas are fairly small but usually encompass several ridges and deep valleys. We use vertical polarisation with a 5/8 whip on the repeater and the search teams have flexible dipoles that fit into their backpacks. Sharp ridges and steep slopes contribute to coverage problems. Would circular polarization help?? I think not. Remember, a quarter-wave has significant energy in the pattern from about five degrees to eighty-five degrees; if you're dealing with valleys, this may be a better choice for an antenna. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Thu, 2 Sep 2010, Paul Plack wrote: Gordon, something worth trying might be low-band. About 20 years ago, I lived in an area where hams did course communications for rally events in very mountainous terrain. I remember experimenting one night about 2am with my partner at the other end of a heavily wooded course, about 12 miles end-to-end. 444 MHz simplex, 5 watts, colinear mobile whip - no copy. 146 MHz simplex, 5 watts, 5/8-wave mobile whip - no copy, but would barely break the carrier squelch. 29.6 MHz simplex, 4 watts, FM CB conversion, 1.3m helically-wound mobile whip - full quieting and S9+. Motorola Syntor Xs are relatively easy to locate, and can be programmed for 10m to 6m without any retuning. They were designed for 30-50MHz. -- Kris Kirby, KE4AHR Disinformation Analyst
RE: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
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: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of sbjohns...@aol.com Sent: Thursday, September 02, 2010 6:48 AM To: Repeater-Builder@yahoogroups.com 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
[Repeater-Builder] Re: Circular polarization for VHF repeaters?
Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net --- In Repeater-Builder@yahoogroups.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. Over the years I have read about folks employing circular polarization to overcome fading, nulls, multipath, etc. There is so very little written about this topic in amateur circles so I thought I'd bring it up here and see what I could come up with. In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. Best regards, Gary, K7EK
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
On Fri, 3 Sep 2010, Gary - K7EK wrote: Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net If you find a copy out on the 'net, please forward me a copy of the link. -- Kris Kirby, KE4AHR Disinformation Analyst
[Repeater-Builder] Re: Circular polarization for VHF repeaters?
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, 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.
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_contentview=articleid=57Itemid=134 https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_contentview=articleid=57Itemid=134Interesting 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 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.comRepeater-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.
Re: [Repeater-Builder] Re: Circular polarization for VHF repeaters?
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 To: Repeater-Builder Repeater-Builder@yahoogroups.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_contentview=articleid=57Itemid=134 https://www.digitaltraders.com/index.php/index.php/components/com_kunena/template/default_ex/templates/ja_edenite/index.php?option=com_contentview=articleid=57Itemid=134Interesting 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 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.comRepeater-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.
