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Re: [coldwarcomms] Hello and question about Gabriel Antennas

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  • blitz
    What diameter are the dishes? A 10-12 dish will produce from 38-42db gain. Your problem would be to get a suitable connection from your LAN equipment to the
    Message 1 of 6 , Jan 2, 2004
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      What diameter are the dishes?
      A 10-12' dish will produce from 38-42db gain.
      Your problem would be to get a suitable connection from your LAN equipment
      to the waveguide that feeds the dishes.
      Good luck...


      At 19:33 12/19/2003, you wrote:
      >Hello all, first post.
      >
      > I'm not new to radio but I am fairly new to microwave. I have access
      >to a site with the very large Gabriel style antennas still in place.
      >How much gain do they produce? More specifically would they fucntion
      >at 5.8GHz? I was thinking of reusing them for some hops in the
      >unlicensed spectrum.. Any additional input would be welcome..
      >
      >Thank-you
      >
      >Bill
      >
      >
      >
      >
      >
      >Yahoo! Groups Links
      >
      >To visit your group on the web, go to:
      > http://groups.yahoo.com/group/coldwarcomms/
      >
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      > coldwarcomms-unsubscribe@yahoogroups.com
      >
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    • s92187
      ... access ... Hi Bill: These antennas will deliver about 43 dB of gain at that frequency, the antenna itself will operate in any of the microwave bands, the
      Message 2 of 6 , Jan 2, 2004
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        --- In coldwarcomms@yahoogroups.com, "B" <confidenteyes@y...> wrote:
        > Hello all, first post.
        >
        > I'm not new to radio but I am fairly new to microwave. I have
        access
        > to a site with the very large Gabriel style antennas still in place.
        > How much gain do they produce? More specifically would they fucntion
        > at 5.8GHz? I was thinking of reusing them for some hops in the
        > unlicensed spectrum.. Any additional input would be welcome..
        >
        > Thank-you
        >
        > Bill

        Hi Bill:

        These antennas will deliver about 43 dB of gain at that frequency,
        the antenna itself will operate in any of the microwave bands, the
        only limitation you might run into would be the waveguide run to the
        antenna, and the type of transducer installed at the radio end of the
        run. Is this an old AT&T site? If so, if the site was only running
        at 4 GHz, you won't have exactly the optimum waveguide transducer for
        5.8 GHz, but what's there will probably work at least somewhat. If
        it was set up for 4 and 6 GHz, you should have exactly what you need.

        Terry Michaels
      • Mike Jacobs
        I might also have some concern about how well the polarization network that transitions from the rectangular to circular waveguide will handle the NII band,
        Message 3 of 6 , Jan 2, 2004
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          I might also have some concern about how well the polarization
          network that transitions from the rectangular to circular waveguide
          will handle the NII band, but I don't know enough about its operation
          to be sure. The horn antennas and waveguides will all be
          broadband enough, and as Terry pointed out, if you can get a
          transition that was made for 4/6 GHz you should be in good shape.
          By the way, the flanges on Bell System rectangular waveguide don't
          match the standard flanges you get from Narda, etc., so your best
          bet is to scavange for transitions at other AT&T sites.

          By "Gabriel Antennas", I am assuming you mean the cornucopia
          type with a horn at the bottom and circular reflector at the top. If it is
          a dish antenna, then the performance may be limited by the
          feedhorn. Generally you can operate waveguide structures at
          frequencies higher than their design, but you may wind up with
          moding problems (where the waveguide stores or inefficiently
          transfers energy) if you go too high above the design frequency. If
          you try to operate a waveguide below its design frequency you will
          run into a cutoff situation where it won't accept any energy at all.
          This is easily seen as a high SWR situation. The moding problem
          may not be obvious, since the waveguide may show good SWR, but
          you won't be getting the full power out of the antenna. If your link
          doesn't work but the SWR seems ok, this may be the culprit. I
          would expect that a problem at the network may show up as a SWR
          spike at the input, but cannot be certain.

          Sorry for the physics lesson there...

          Mike


          > --- In coldwarcomms@yahoogroups.com, "B" <confidenteyes@y...> wrote:
          > > Hello all, first post.
          > >
          > > I'm not new to radio but I am fairly new to microwave. I have
          > access
          > > to a site with the very large Gabriel style antennas still in place.
          > > How much gain do they produce? More specifically would they fucntion
          > > at 5.8GHz? I was thinking of reusing them for some hops in the
          > > unlicensed spectrum.. Any additional input would be welcome..
          > >
          > > Thank-you
          > >
          > > Bill
          >
          > Hi Bill:
          >
          > These antennas will deliver about 43 dB of gain at that frequency,
          > the antenna itself will operate in any of the microwave bands, the
          > only limitation you might run into would be the waveguide run to the
          > antenna, and the type of transducer installed at the radio end of the
          > run. Is this an old AT&T site? If so, if the site was only running
          > at 4 GHz, you won't have exactly the optimum waveguide transducer for
          > 5.8 GHz, but what's there will probably work at least somewhat. If
          > it was set up for 4 and 6 GHz, you should have exactly what you need.
          >
          > Terry Michaels
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          > To visit your group on the web, go to:
          > http://groups.yahoo.com/group/coldwarcomms/
          >
          > To unsubscribe from this group, send an email to:
          > coldwarcomms-unsubscribe@yahoogroups.com
          >
          > Your use of Yahoo! Groups is subject to:
          > http://docs.yahoo.com/info/terms/
          >
        • Jay Panozzo
          Ahhh yes, license free 5.8 GHz, the Yugo band of microwave..... I was wondering if a simple waveguide to N adapter at the feed would work? (if its a parabolic)
          Message 4 of 6 , Jan 2, 2004
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            Ahhh yes, license free 5.8 GHz, the Yugo band of microwave.....

            I was wondering if a simple waveguide to N adapter at the feed would
            work? (if its a parabolic)

            If it's a horn, maybe a mode filter & transistion could be used with
            the Type N adapter?

            With all those dead Norlight sites in WI someone should be able to
            come up with one or two?


            Jay Panozzo
          • blitz
            There are adaptors that transform type N s to waveguide.....used them in microwave, try microflect if theyre still around..
            Message 5 of 6 , Jan 3, 2004
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              There are adaptors that transform type N's to waveguide.....used them in
              microwave, try microflect if theyre still around..

              At 02:01 1/3/2004, you wrote:
              >Ahhh yes, license free 5.8 GHz, the Yugo band of microwave.....
              >
              >I was wondering if a simple waveguide to N adapter at the feed would
              >work? (if its a parabolic)
              >
              >If it's a horn, maybe a mode filter & transistion could be used with
              >the Type N adapter?
              >
              >With all those dead Norlight sites in WI someone should be able to
              >come up with one or two?
              >
              >
              >Jay Panozzo
              >
              >
              >
              >
              >Yahoo! Groups Links
              >
              >To visit your group on the web, go to:
              > http://groups.yahoo.com/group/coldwarcomms/
              >
              >To unsubscribe from this group, send an email to:
              > coldwarcomms-unsubscribe@yahoogroups.com
              >
              >Your use of Yahoo! Groups is subject to:
              > http://docs.yahoo.com/info/terms/
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