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Re: [wsjtgroup] Circular Polarization for WSJT Meteor Scatter

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  • Lance Collister, W7GJ
    Hi Les, My guess is that you might notice the 3 dB loss from working linearly polarized stations. I don t have any current experience running 2m meteor
    Message 1 of 10 , Mar 25, 2013
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      Hi Les,

      My guess is that you might notice the 3 dB loss from working linearly polarized
      stations. I don't have any current experience running 2m meteor scatter with
      FSK441, but on 6m, you can clearly see the rapid QSB from rotating polarity during
      the longer burns. I suspect the same thing is true on 2m, and the polarity rotates
      during a meteor scatter contact. While circular polarization would even this out,
      I am not sure it is an advantage, since the proper polarization comes around often
      enough and signals are usually strong enough to permit signal decode even during the
      fades - especially if you have good ground gain and a high gain yagi.

      Since there are difficulties in obtaining true circular polarization when aimed on
      the horizon (which is where you need to be for long distance meteor scatter, as well
      as maximum ground gain), as well as mechanical challenges in trying to properly mount
      such a yagi so that none of the support structure or coaxial cable is interferes with
      either polarity, I suggest you just stick with the biggest horizontally polarized
      yagi you can put up, and run the coax and supporting mast away from it at right
      angles to the elements.

      GL and VY 73, Lance

      On 3/25/2013 8:09 AM, Les Rayburn wrote:
      > My math is not as strong as it should be so please indulge my questions.
      > But I'm wondering if using a circularly polarized antenna on 2 Meters,
      > such as the M2 2MCP14 would
      > improve performance for station on 2 Meter meteor scatter vs. a
      > traditional horizontally polarized Yagi?
      >
      > To be specific, I'd wonder about the following:
      >
      > 1.) If two stations at or near the maximum possible MS distance both
      > used circular polarized antennas would they see a greater chance of
      > completing a QSO vs. both
      > of them running horizontal antennas?
      >
      > 2.) What if only one station used the circular antenna? Would they still
      > have a greater chance of completing? (The most likely scenario since
      > most of us can only affect
      > what happens at our own station)
      >
      > My understanding is that circular polarization works best when one of
      > the antennas in question is moving and changing it's polarization over
      > time during a contact, such
      > as a satellite in LEO or an aircraft such as a balloon or rocket. But it
      > would seem that the radio wave striking the ionized trail of a
      > fast-moving meteor would also be subject
      > to polarization shifts? Or is the time domain too brief (especially with
      > WSJT) to see any practical benefit?
      >
      > Inquiring minds want to know. Can some of the smart people dumb it down
      > for me? Much appreciated!
      >
      >


      --
      Lance Collister, W7GJ
      (ex WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX, 3D2LR, 5W0GJ, E6M)
      P.O. Box 73
      Frenchtown, MT 59834-0073
      USA
      TEL: (406) 626-5728
      QTH: DN27ub
      URL: http://www.bigskyspaces.com/w7gj
      Windows Messenger: W7GJ@...
      Skype: lanceW7GJ
      2m DXCC #11/6m DXCC #815

      Interested in 6m EME? Ask me about subscribing to the Magic Band EME
      email group, or just fill in the request box at the bottom of my web
      page (above)!
    • Marshall-K5QE
      Hello everyone....I like everything that Lance has said except the part about the biggest horizontally polarized yagi you can put up .....IF Lance meant the
      Message 2 of 10 , Mar 25, 2013
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        Hello everyone....I like everything that Lance has said except the part about the "biggest horizontally polarized yagi you can put up".....IF Lance meant  the "biggest horizontally polarized SINGLE yagi you can put up", then he is most probably correct.  However, when I first read his post, I read the "biggest horizontally polarized antenna that you can put up".  I know that is not what he wrote, but that is what my (silly) mind read out of it.

        When running meteor scatter, you need to illuminate a lot of sky....especially for contacts of the short range to medium range types.  That is because there are always "off path" meteors that your signal can interact with to produce a "burn" on the other end.  If you don't illuminate those, the chap on the other end does not hear a lot of "pings".  For the really long range contacts, everything is more or less down the "bore sight", so that off path meteors don't really produce much on the other end. 

        I guess you can argue about how much sky needs to be illuminated, but the concept is correct.  Once when I lived in Oklahoma City, K5JL-Jay called me and told me to get on 2M as there was a big aurora happening.  Well folks, aurora is VERY rare that far south, so I raced to get on the air.  I swung the antenna back and forth and could not hear anything.  I called Jay back on the phone and told him there was nothing there.  He put the phone to his speaker and said, "Listen to this!!".   There were buzz mode signals all over everywhere.  Well, I was using 4 x 20el of Cushcraft collinear for my antenna.  It just did not illuminate the auroral cloud--it was too tight.  I finally found one station that I could hear and worked him, but that was it.  So, at least for aurora, I had too much antenna and did not illuminate enough sky. 

        This means that for short to medium range contacts, a single medium to long yagi is a very good choice.  For the really long range QSOs, however, you want a stacked pair of the longest yagis you can get.  As everyone knows, the stacking reduces the energy in the vertical plane and tends to focus it right on the horizon.  Right at the horizon is the geometry you want for the really long MS shots.  BUT, you can over do this....I have tried my 8 x 18el 2M EME antenna on MS and the results were really exceedingly poor.  That antenna just does not illuminate very much sky.  So, unfortunately, bigger is not always better.

        NOW A QUESTION:  On 6M, I have a 7el at 100ft that I can use for MS.  On the advice of the experts from K9NS(namely W9RM-Jay and K9PW-Pete), I installed a Low6 antenna.  In particular, a 7el at 30ft.  I was just amazed at how much more "stuff" I was hearing on the Low6 antenna on the short to medium range shots.  Now, on 2M, I have 2 x 17el at 160ft and I use that for MS.  We do OK, but we don't burn up any barns with it.  I wonder if the group feels that I need a Low2 antenna for MS??  Maybe something like a 2M12 at 25ft or some such??  If you feel that your reply has value for the entire group, then feel free to post on the reflector.  If not, then please reply direct to me.  I really am interested in the group's ideas here.

        It may be that 2M(being almost 3X in frequency) is significantly different from 6M in this respect(needing a low antenna for short to medium MS) so that a Low2 antenna is not going to profit me much.  If anyone has some genius ideas here, I would sure like to learn the answers to these questions.  Inquiring minds want to know......

        73 Marshall K5QE

        On 3/25/2013 9:25 AM, Lance Collister, W7GJ wrote:
         

        Hi Les,

        My guess is that you might notice the 3 dB loss from working linearly polarized
        stations. I don't have any current experience running 2m meteor scatter with
        FSK441, but on 6m, you can clearly see the rapid QSB from rotating polarity during
        the longer burns. I suspect the same thing is true on 2m, and the polarity rotates
        during a meteor scatter contact. While circular polarization would even this out,
        I am not sure it is an advantage, since the proper polarization comes around often
        enough and signals are usually strong enough to permit signal decode even during the
        fades - especially if you have good ground gain and a high gain yagi.

        Since there are difficulties in obtaining true circular polarization when aimed on
        the horizon (which is where you need to be for long distance meteor scatter, as well
        as maximum ground gain), as well as mechanical challenges in trying to properly mount
        such a yagi so that none of the support structure or coaxial cable is interferes with
        either polarity, I suggest you just stick with the biggest horizontally polarized
        yagi you can put up, and run the coax and supporting mast away from it at right
        angles to the elements.

        GL and VY 73, Lance

        On 3/25/2013 8:09 AM, Les Rayburn wrote:
        > My math is not as strong as it should be so please indulge my questions.
        > But I'm wondering if using a circularly polarized antenna on 2 Meters,
        > such as the M2 2MCP14 would
        > improve performance for station on 2 Meter meteor scatter vs. a
        > traditional horizontally polarized Yagi?
        >
        > To be specific, I'd wonder about the following:
        >
        > 1.) If two stations at or near the maximum possible MS distance both
        > used circular polarized antennas would they see a greater chance of
        > completing a QSO vs. both
        > of them running horizontal antennas?
        >
        > 2.) What if only one station used the circular antenna? Would they still
        > have a greater chance of completing? (The most likely scenario since
        > most of us can only affect
        > what happens at our own station)
        >
        > My understanding is that circular polarization works best when one of
        > the antennas in question is moving and changing it's polarization over
        > time during a contact, such
        > as a satellite in LEO or an aircraft such as a balloon or rocket. But it
        > would seem that the radio wave striking the ionized trail of a
        > fast-moving meteor would also be subject
        > to polarization shifts? Or is the time domain too brief (especially with
        > WSJT) to see any practical benefit?
        >
        > Inquiring minds want to know. Can some of the smart people dumb it down
        > for me? Much appreciated!
        >
        >

        --
        Lance Collister, W7GJ
        (ex WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX, 3D2LR, 5W0GJ, E6M)
        P.O. Box 73
        Frenchtown, MT 59834-0073
        USA
        TEL: (406) 626-5728
        QTH: DN27ub
        URL: http://www.bigskyspaces.com/w7gj
        Windows Messenger: W7GJ@...
        Skype: lanceW7GJ
        2m DXCC #11/6m DXCC #815

        Interested in 6m EME? Ask me about subscribing to the Magic Band EME
        email group, or just fill in the request box at the bottom of my web
        page (above)!


      • Steve
        ... I am considering the same thing. I plan to have, at some point, an array of two cross polarized 2M yagis. I intend to transmit circular and receive with
        Message 3 of 10 , Mar 25, 2013
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          --- In wsjtgroup@yahoogroups.com, Les Rayburn <les@...> wrote:
          >
          > My math is not as strong as it should be so please indulge my questions.
          > But I'm wondering if using a circularly polarized antenna on 2 Meters,

          I am considering the same thing. I plan to have, at some point, an array of two cross polarized 2M yagis. I intend to transmit circular and receive with separate feed lines to two synchronized receivers. The receivers will run on MAP65 for JT65 and probably run to two independent FSK441 decoders for MS.

          So far I have the yagis and an AZ/EL rotor (thanks to craigs list). I have a pair of Ensemble II SDR receivers that are synchronized for a 28MHz IF. I have tried the receivers on JT65 HF with success. I have tons more work to do before the system is on the air for EME and MS. Unfortunately, other hobbies, work, and life get in the way of Ham Radio.

          So I have not answered your question but I wanted to let you know that you are not alone in your curiosity about circular polarization for MS.

          Steve,
          WA6VCR
        • Dan Bates
          I agree with Marshall regarding too much antenna for MS work. Meteor Scatter is not a weak signal mode, but rather a short burst mode. A modest antenna with a
          Message 4 of 10 , Mar 25, 2013
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            I agree with Marshall regarding too much antenna for MS work. 

             

            Meteor Scatter is not a weak signal mode, but rather a short burst mode.  A modest antenna with a broad horizontal pattern works better than a large array with a very narrow beam width.

             

            On a number of occasions I have had much trouble working the EME large array stations on 2m MS versus  a station with a single yagi, both at the same distance.  Further it was very frustrating for the EME station when often they were hearing me, but I was not hearing them.  I believe this is because a modest antenna is spraying out in a broad pattern, therefore illuminating off heading burns while an eme bore site array will be missing those off heading trails.  Like trying to shoot ducks with a rifle. 

             

            When you look at the geometry of the MS reflections, there is a spray back down in a fan pattern depending on the angle to the ion trail.  So if you can illuminate the burn your signal will be spread out on the other end.  If you miss the burn due to a too tight pattern, there is nothing on the other end.

            There is a really excellent description of MS geometries in the PSK2K user’s manual from  Klaus.  http://www.dj5hg.de/PSK2k_UserGuide.pdf

             

            Regarding the height of the antenna, I’m very successful here with a 6 meter 5el LFA at 35ft.  

             

            I have a pair of 2m7s for two meters.  The top antenna is at 40ft and this also works very well for MS.  By stacking a pair of 7 element antennas I have increased the gain toward the horizon while keeping the relatively wide beam width of the short antenna.

             

             

            Dan n5tm

             

            From: Marshall-K5QE [mailto:k5qe@...]
            Sent: Monday, March 25, 2013 1:27 PM
            Cc: WSJT Group
            Subject: [wsjtgroup] Illuminating the sky....

             

             

            Hello everyone....I like everything that Lance has said except the part about the "biggest horizontally polarized yagi you can put up".....IF Lance meant  the "biggest horizontally polarized SINGLE yagi you can put up", then he is most probably correct.  However, when I first read his post, I read the "biggest horizontally polarized antenna that you can put up".  I know that is not what he wrote, but that is what my (silly) mind read out of it.

            When running meteor scatter, you need to illuminate a lot of sky....especially for contacts of the short range to medium range types.  That is because there are always "off path" meteors that your signal can interact with to produce a "burn" on the other end.  If you don't illuminate those, the chap on the other end does not hear a lot of "pings".  For the really long range contacts, everything is more or less down the "bore sight", so that off path meteors don't really produce much on the other end. 

            I guess you can argue about how much sky needs to be illuminated, but the concept is correct.  Once when I lived in Oklahoma City, K5JL-Jay called me and told me to get on 2M as there was a big aurora happening.  Well folks, aurora is VERY rare that far south, so I raced to get on the air.  I swung the antenna back and forth and could not hear anything.  I called Jay back on the phone and told him there was nothing there.  He put the phone to his speaker and said, "Listen to this!!".   There were buzz mode signals all over everywhere.  Well, I was using 4 x 20el of Cushcraft collinear for my antenna.  It just did not illuminate the auroral cloud--it was too tight.  I finally found one station that I could hear and worked him, but that was it.  So, at least for aurora, I had too much antenna and did not illuminate enough sky. 

            This means that for short to medium range contacts, a single medium to long yagi is a very good choice.  For the really long range QSOs, however, you want a stacked pair of the longest yagis you can get.  As everyone knows, the stacking reduces the energy in the vertical plane and tends to focus it right on the horizon.  Right at the horizon is the geometry you want for the really long MS shots.  BUT, you can over do this....I have tried my 8 x 18el 2M EME antenna on MS and the results were really exceedingly poor.  That antenna just does not illuminate very much sky.  So, unfortunately, bigger is not always better.

            NOW A QUESTION:  On 6M, I have a 7el at 100ft that I can use for MS.  On the advice of the experts from K9NS(namely W9RM-Jay and K9PW-Pete), I installed a Low6 antenna.  In particular, a 7el at 30ft.  I was just amazed at how much more "stuff" I was hearing on the Low6 antenna on the short to medium range shots.  Now, on 2M, I have 2 x 17el at 160ft and I use that for MS.  We do OK, but we don't burn up any barns with it.  I wonder if the group feels that I need a Low2 antenna for MS??  Maybe something like a 2M12 at 25ft or some such??  If you feel that your reply has value for the entire group, then feel free to post on the reflector.  If not, then please reply direct to me.  I really am interested in the group's ideas here.

            It may be that 2M(being almost 3X in frequency) is significantly different from 6M in this respect(needing a low antenna for short to medium MS) so that a Low2 antenna is not going to profit me much.  If anyone has some genius ideas here, I would sure like to learn the answers to these questions.  Inquiring minds want to know......

            73 Marshall K5QE

            On 3/25/2013 9:25 AM, Lance Collister, W7GJ wrote:

             

            Hi Les,

            My guess is that you might notice the 3 dB loss from working linearly polarized
            stations. I don't have any current experience running 2m meteor scatter with
            FSK441, but on 6m, you can clearly see the rapid QSB from rotating polarity during
            the longer burns. I suspect the same thing is true on 2m, and the polarity rotates
            during a meteor scatter contact. While circular polarization would even this out,
            I am not sure it is an advantage, since the proper polarization comes around often
            enough and signals are usually strong enough to permit signal decode even during the
            fades - especially if you have good ground gain and a high gain yagi.

            Since there are difficulties in obtaining true circular polarization when aimed on
            the horizon (which is where you need to be for long distance meteor scatter, as well
            as maximum ground gain), as well as mechanical challenges in trying to properly mount
            such a yagi so that none of the support structure or coaxial cable is interferes with
            either polarity, I suggest you just stick with the biggest horizontally polarized
            yagi you can put up, and run the coax and supporting mast away from it at right
            angles to the elements.

            GL and VY 73, Lance

            On 3/25/2013 8:09 AM, Les Rayburn wrote:
            > My math is not as strong as it should be so please indulge my questions.
            > But I'm wondering if using a circularly polarized antenna on 2 Meters,
            > such as the M2 2MCP14 would
            > improve performance for station on 2 Meter meteor scatter vs. a
            > traditional horizontally polarized Yagi?
            >
            > To be specific, I'd wonder about the following:
            >
            > 1.) If two stations at or near the maximum possible MS distance both
            > used circular polarized antennas would they see a greater chance of
            > completing a QSO vs. both
            > of them running horizontal antennas?
            >
            > 2.) What if only one station used the circular antenna? Would they still
            > have a greater chance of completing? (The most likely scenario since
            > most of us can only affect
            > what happens at our own station)
            >
            > My understanding is that circular polarization works best when one of
            > the antennas in question is moving and changing it's polarization over
            > time during a contact, such
            > as a satellite in LEO or an aircraft such as a balloon or rocket. But it
            > would seem that the radio wave striking the ionized trail of a
            > fast-moving meteor would also be subject
            > to polarization shifts? Or is the time domain too brief (especially with
            > WSJT) to see any practical benefit?
            >
            > Inquiring minds want to know. Can some of the smart people dumb it down
            > for me? Much appreciated!
            >
            >

            --
            Lance Collister, W7GJ
            (ex WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX, 3D2LR, 5W0GJ, E6M)
            P.O. Box 73
            Frenchtown, MT 59834-0073
            USA
            TEL: (406) 626-5728
            QTH: DN27ub
            URL: http://www.bigskyspaces.com/w7gj
            Windows Messenger: W7GJ@...
            Skype: lanceW7GJ
            2m DXCC #11/6m DXCC #815

            Interested in 6m EME? Ask me about subscribing to the Magic Band EME
            email group, or just fill in the request box at the bottom of my web
            page (above)!

             

          • Joe Taylor
            Hi Les and all, ... Polarization is largely preserved in MS propagation, so you re best off with horizontal polarization. As for how big , see the short
            Message 5 of 10 , Mar 25, 2013
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              Hi Les and all,

              Les Rayburn wrote:

              > I'm wondering if using a circularly polarized antenna on 2 Meters,
              > such as the M2 2MCP14 would
              > improve performance for station on 2 Meter meteor scatter vs. a
              > traditional horizontally polarized Yagi?

              Polarization is largely preserved in MS propagation, so you're best off
              with horizontal polarization. As for "how big", see the short piece I
              wrote for the ARRL Antenna Book, 22nd Edition (2011). A copy is posted
              in the WSJT web site,
              http://physics.princeton.edu/pulsar/K1JT/refs.html .

              Click on reference #17.

              -- 73, Joe, K1JT
            • Les Rayburn
              Thanks to Joe, Lance, Russ, and everyone who took time to answer my questions either on the list or direct. I m always amazed at the wealth of knowledge within
              Message 6 of 10 , Mar 25, 2013
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                Thanks to Joe, Lance, Russ, and everyone who took time to answer my
                questions either on the list
                or direct. I'm always amazed at the wealth of knowledge within this
                hobby and those active on WSJT
                in particular.

                Also--how cool is it to have a question answered by a Nobel Prize
                winner! :-) Is this a great hobby or what?

                73,

                Les Rayburn, N1LF



                On 3/25/2013 2:41 PM, Joe Taylor wrote:
                > Hi Les and all,
                >
                > Les Rayburn wrote:
                >
                >> I'm wondering if using a circularly polarized antenna on 2 Meters,
                >> such as the M2 2MCP14 would
                >> improve performance for station on 2 Meter meteor scatter vs. a
                >> traditional horizontally polarized Yagi?
                >
                > Polarization is largely preserved in MS propagation, so you're best
                > off with horizontal polarization. As for "how big", see the short
                > piece I wrote for the ARRL Antenna Book, 22nd Edition (2011). A copy
                > is posted in the WSJT web site,
                > http://physics.princeton.edu/pulsar/K1JT/refs.html .
                >
                > Click on reference #17.
                >
                > -- 73, Joe, K1JT
                >
              • Robert
                But of course, Les......it s ham radio, the greatest hobby in the world! 73 Robert W4RL
                Message 7 of 10 , Mar 25, 2013
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                  But of course, Les......it's ham radio, the greatest hobby in the world!

                  73 Robert W4RL


                  On 3/25/2013 3:08 PM, Les Rayburn wrote:
                   

                  Thanks to Joe, Lance, Russ, and everyone who took time to answer my
                  questions either on the list
                  or direct. I'm always amazed at the wealth of knowledge within this
                  hobby and those active on WSJT
                  in particular.

                  Also--how cool is it to have a question answered by a Nobel Prize
                  winner! :-) Is this a great hobby or what?

                  73,

                  Les Rayburn, N1LF

                  On 3/25/2013 2:41 PM, Joe Taylor wrote:
                  > Hi Les and all,
                  >
                  > Les Rayburn wrote:
                  >
                  >> I'm wondering if using a circularly polarized antenna on 2 Meters,
                  >> such as the M2 2MCP14 would
                  >> improve performance for station on 2 Meter meteor scatter vs. a
                  >> traditional horizontally polarized Yagi?
                  >
                  > Polarization is largely preserved in MS propagation, so you're best
                  > off with horizontal polarization. As for "how big", see the short
                  > piece I wrote for the ARRL Antenna Book, 22nd Edition (2011). A copy
                  > is posted in the WSJT web site,
                  > http://physics.princeton.edu/pulsar/K1JT/refs.html .
                  >
                  > Click on reference #17.
                  >
                  > -- 73, Joe, K1JT
                  >


                • john flinn w9se
                  From: w9se@msn.com To: les@highnoonfilm.com Subject: RE: [wsjtgroup] Circular Polarization for WSJT Meteor Scatter Date: Mon, 25 Mar 2013 16:50:49 -0500 Hi
                  Message 8 of 10 , Mar 25, 2013
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                    From: w9se@...
                    To: les@...
                    Subject: RE: [wsjtgroup] Circular Polarization for WSJT Meteor Scatter
                    Date: Mon, 25 Mar 2013 16:50:49 -0500

                    Hi Les,
                         I have been using a small 2 el Moxon at 10 feet off the ground pointed straight up.  My theory being the more sky I can light up the more stations I will work on MS.  This antenna works great out to 800 miles or so but of course it's no good beyond that point.  My "big" antenna is a 2 el Moxon at 30 feet.  A few years ago I had a Moxon/Yagi for 2 meters.  2 el moxon at 30 feet with 3 Yagi directors and 100 watts.  Worked over 100 grids with this setup but never tried it at 90 degs elevation.
                    John W9SE


                    To: wsjtgroup@yahoogroups.com; vhf@...
                    From: les@...
                    Date: Mon, 25 Mar 2013 03:09:04 -0500
                    Subject: [wsjtgroup] Circular Polarization for WSJT Meteor Scatter

                     
                    My math is not as strong as it should be so please indulge my questions.
                    But I'm wondering if using a circularly polarized antenna on 2 Meters,
                    such as the M2 2MCP14 would
                    improve performance for station on 2 Meter meteor scatter vs. a
                    traditional horizontally polarized Yagi?

                    To be specific, I'd wonder about the following:

                    1.) If two stations at or near the maximum possible MS distance both
                    used circular polarized antennas would they see a greater chance of
                    completing a QSO vs. both
                    of them running horizontal antennas?

                    2.) What if only one station used the circular antenna? Would they still
                    have a greater chance of completing? (The most likely scenario since
                    most of us can only affect
                    what happens at our own station)

                    My understanding is that circular polarization works best when one of
                    the antennas in question is moving and changing it's polarization over
                    time during a contact, such
                    as a satellite in LEO or an aircraft such as a balloon or rocket. But it
                    would seem that the radio wave striking the ionized trail of a
                    fast-moving meteor would also be subject
                    to polarization shifts? Or is the time domain too brief (especially with
                    WSJT) to see any practical benefit?

                    Inquiring minds want to know. Can some of the smart people dumb it down
                    for me? Much appreciated!

                    --
                    73,

                    Les Rayburn, N1LF
                    121 Mayfair Park
                    Maylene, AL 35114
                    EM63nf

                    6M VUCC #1712
                    Grid Bandits #222
                    Central States VHF Society Life Member

                    Active on 6 Meters thru 1296, 10GHz & Light


                  • Palle Preben-Hansen, OZ1RH
                    Hello, I wrote this text a few days ago on Yahoogroups web interface, but as I have not seen it reflected I try again. Lance wrote: * on 6m, you can clearly
                    Message 9 of 10 , Mar 27, 2013
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                      Hello, I wrote this text a few days ago on Yahoogroups web interface, but as I have not seen it reflected I try again.

                       

                      Lance wrote:

                      >on 6m, you can clearly see the rapid QSB from rotating polarity during the longer burns

                      I have a detailed description of MS at http://www.uksmg.org/content/deadband.htm but I did not consider circular polarization. MS is forward reflection which generally preserves polarization. Thus no point in using circular polarization as Joe wrote. The rapid QSB on 6 m MS sound like rotating polarity, but come from high speed wind in the ionosphere blowing the meteor trail into several reflection areas.

                       

                      The needed azimuth for MS is not great circle bearing as the reflections comes from about areas +-10 degrees from hotspot A and B. Hotspot A and B can be +- 10 degrees or more from great circle bearing and are calculated by WSJT. Thus if your antenna is narrower than about +-10 degrees is might not be optimum and you should in any case understand hotspot A and B so you know where to beam. If you want to call CQ you should have a fairly wide beam in azimuth.

                       

                      The needed radiation angle in the vertical plane depends on the distance and the elevation is less than 13-15 degrees, see the curve in my text. This is not the elevation angle of your boom but the radiation angle of your antenna, which almost only is a function of antenna height over ground. Radiation angle is described in "Ground gain and radiation angle at VHF" at www.oz1rh.com Pointing your antenna at 90 deg EL for MS is seldom optimum.

                       

                      Remember that the mentioned degrees represents statistical probabilities of where the reflections might come from, thus an antenna one degree too narrow does not mean no QSO’s.

                       

                      BTW if you have a good station on 6 m you might consider exploring ionoscatter described in “Ionoscatter on 50 and 144 MHz" at www.oz1rh.com WSJT mode ISCAT is optimized for a combination of MS and ionoscatter on 6 m.

                       

                      73, Palle, OZ1RH (team OZ5W/OZ9EDR)

                      palle at oz1rh.com

                       

                      --- In wsjtgroup@yahoogroups.com, "Lance Collister, W7GJ" <w7gj@...> wrote:

                      > Hi Les,

                      >

                      > My guess is that you might notice the 3 dB loss from working

                      linearly polarized

                      > stations.   I don't have any

                      current experience running 2m meteor scatter with

                      > FSK441, but on 6m, you can clearly see the rapid QSB from rotating

                      polarity during

                      > the longer burns. I suspect the same thing is true on 2m, and the

                      polarity rotates

                      > during a meteor scatter contact.

                      - rest snipped

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