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what would you have?

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  • jefeickert
    If I were to make a loop antenna like Wellbrook type , using copper tubing and also running a wire inside the tube as well? JIM F.
    Message 1 of 10 , Nov 29, 2007
      If I were to make a loop antenna like Wellbrook type , using copper tubing and
      also running a wire inside the tube as well?
      JIM F.
    • james feickert
      ... JIM F. ... ____________________________________________________________________________________ Be a better sports nut! Let your teams follow you with
      Message 2 of 10 , Nov 29, 2007
        --- jefeickert <jefeickert@...> wrote:

        > If I were to make a loop antenna like Wellbrook type
        > , using copper tubing and
        > also running a wire inside the tube as well?
        >what I have?
        JIM F.
        >
        >



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      • mhatlau
        If you have the electronic assembly and mechanical assembly skills, you might want to take a close look at Lankford s Active Dipole. It is probably better
        Message 3 of 10 , Nov 29, 2007
          If you have the electronic assembly and mechanical assembly skills,
          you might want to take a close look at Lankford's Active Dipole. It
          is probably better than the Wellbrook by a small margen, and cheaper
          to boot. Lankford has gone to some lengths to design and test SW
          Antennas in noisy areas.

          --- In loopantennas@yahoogroups.com, "jefeickert" <jefeickert@...> wrote:
          >
          > If I were to make a loop antenna like Wellbrook type , using copper
          tubing and
          > also running a wire inside the tube as well?
          > JIM F.
          >
        • james feickert
          I LL give a look ... ____________________________________________________________________________________ Be a better pen pal. Text or chat with friends inside
          Message 4 of 10 , Nov 29, 2007
            I'LL give a look
            --- mhatlau <mhuss1@...> wrote:

            > If you have the electronic assembly and mechanical
            > assembly skills,
            > you might want to take a close look at Lankford's
            > Active Dipole. It
            > is probably better than the Wellbrook by a small
            > margen, and cheaper
            > to boot. Lankford has gone to some lengths to
            > design and test SW
            > Antennas in noisy areas.
            >
            > --- In loopantennas@yahoogroups.com, "jefeickert"
            > <jefeickert@...> wrote:
            > >
            > > If I were to make a loop antenna like Wellbrook
            > type , using copper
            > tubing and
            > > also running a wire inside the tube as well?
            > > JIM F.
            > >
            >
            >
            >



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          • Richards
            I cannot see any advantage to putting a wire inside a copper loop as you suggest. The signal would be picked up on the copper loop which would, I think,
            Message 5 of 10 , Nov 30, 2007
              I cannot see any advantage to putting a wire inside a copper loop as you
              suggest. The signal would be picked up on the copper loop which would,
              I think, shield the wire inside -- consider = if thin gauge coaxial
              cable braid shields the inner conductor on coax cable, then certainly
              the copper tubing would shield any wire inside it from receiving any signal.

              Just my take

              Happy Trails and 73. ///// Richards - KD8JHR /////
              ====================================================

              jefeickert wrote:
              > If I were to make a loop antenna like Wellbrook type , using copper tubing and
              > also running a wire inside the tube as well?
              > JIM F.
              >
            • Michael Hebert
              Richards, About a year ago I tried an experiment down in the 0-15Hz region with one of my large rescued TV degaussing coil magfield sensors. Untuned, of
              Message 6 of 10 , Nov 30, 2007
                Richards,

                About a year ago I tried an experiment down in the 0-15Hz region with
                one of my large "rescued" TV degaussing coil magfield sensors.
                Untuned, of course. These things typically have about 250 or so turns
                of about 24g. wire. The one I used was almost 1-mtr diameter. I
                wrapped the whole loop in aluminum foil with _no_ gap. Rather than
                decreasing the loop's response it increased it! Shorted turns reduce
                performance? Bah, humbug! It depends on how they are used. In this
                case I believe the close coupling was producing a transformer action
                with currents flowing on the single-turn shorted "shield" inducing
                voltage in the enclosed loop's turns.

                A more recent experiment involved two almost identical degaussing coil
                loops. When taped adjacent to each other and hooked together in either
                series or parallel aiding there was a reduction of "signal" compared
                to either loop alone. Separating the two loops by at least one loop
                diameter produced an increase in signal response compared to either
                loop standing alone. The separation also created a sharper null in the
                loop pattern.

                FWIW.

                73,

                'Bear' NH7SR
              • Richards
                Mysterious, indeed. This is a most interesting hobby. I would not have figured it that way. Thanks for the reply !! ////////////////////// Richards
                Message 7 of 10 , Nov 30, 2007
                  Mysterious, indeed. This is a most interesting hobby. I would
                  not have figured it that way.

                  Thanks for the reply !!

                  ////////////////////// Richards ////////////////////
                  ==============================================

                  Michael Hebert wrote:
                  > wrapped the whole loop in aluminum foil with _no_ gap. Rather than
                  > decreasing the loop's response it increased it!

                  Shorted turns reduce
                  > performance? Bah, humbug! It depends on how they are used.

                  ================================================
                • james feickert
                  mm that makes sense JIM F ... ____________________________________________________________________________________ Get easy, one-click access to your
                  Message 8 of 10 , Nov 30, 2007
                    mm that makes sense JIM F
                    --- Richards <jruing@...> wrote:

                    > I cannot see any advantage to putting a wire inside
                    > a copper loop as you
                    > suggest. The signal would be picked up on the
                    > copper loop which would,
                    > I think, shield the wire inside -- consider = if
                    > thin gauge coaxial
                    > cable braid shields the inner conductor on coax
                    > cable, then certainly
                    > the copper tubing would shield any wire inside it
                    > from receiving any signal.
                    >
                    > Just my take
                    >
                    > Happy Trails and 73. ///// Richards - KD8JHR
                    > /////
                    > ====================================================
                    >
                    > jefeickert wrote:
                    > > If I were to make a loop antenna like Wellbrook
                    > type , using copper tubing and
                    > > also running a wire inside the tube as well?
                    > > JIM F.
                    > >
                    >



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                  • Paul Birke
                    Dear Richards we sometimes forget what Michael Faraday told us to do we must experiment with Nature to unlock the clues best Paul says me guilty as hell of
                    Message 9 of 10 , Nov 30, 2007
                      Dear Richards

                      we sometimes forget what Michael Faraday told us to do

                      we must experiment with Nature to unlock the clues

                      best
                      Paul

                      says me guilty as hell of computer simulation LOL

                      ----- Original Message ----
                      From: Richards <jruing@...>
                      To: loopantennas@yahoogroups.com
                      Sent: Friday, November 30, 2007 11:58:56 PM
                      Subject: Re: [loopantennas] Re: what would you have?













                      Mysterious, indeed. This is a most interesting hobby. I would

                      not have figured it that way.



                      Thanks for the reply !!



                      //////////// ///////// / Richards //////////// ////////

                      ============ ========= ========= ========= =======



                      Michael Hebert wrote:

                      > wrapped the whole loop in aluminum foil with _no_ gap. Rather than

                      > decreasing the loop's response it increased it!



                      Shorted turns reduce

                      > performance? Bah, humbug! It depends on how they are used.



                      ============ ========= ========= ========= =========












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                      [Non-text portions of this message have been removed]
                    • mhatlau
                      The advantage is Balance, and the suppression of nearby influance on the directivity and depth of the null. The trade-off is less sensitivity of the antenna.
                      Message 10 of 10 , Dec 1, 2007
                        The advantage is Balance, and the suppression of nearby influance on
                        the directivity and depth of the null. The trade-off is less
                        sensitivity of the antenna. The trick is that you place a gap in the
                        shield opposite the feed point of the loop, and ground the shield at
                        the feed-point. The gap need not be very wide, a quarter inch is
                        plenty. If you do not provide this gap, you will either completely
                        shield the inner wire, so that it does not pick up any signal at all,
                        or create a shorted loop, which will short out the inner wire,
                        reducing the strength of the signal on the inner wire tremendously.
                        The reason why the copper tube, covering 99.9% of the wire, does not
                        shield it has to do with 'Skin Effect'.

                        And to answer Michel Hebert's comment, the answer is that you did
                        indeed have a gap. Now if you wrap a transistorized radio in Aluminum
                        foil, for example, you will note that even though you had it tuned to
                        a strong, local signal, it will go silent. You have provided what is
                        called a Faraday Shield. There is a gap where the aluminum sheets
                        overlap, but the capacitance between them is high enough that it is
                        for all practical purposes shorted together at AM Radio frequencies.
                        But at 15 Hz, the capacitance between the overlapping sheet is low
                        enough it is for all intents an open. The reason for the gap is that
                        aluminum foil is VERY reactive to oxygenation, or rusting. You can
                        remove the rust layer from Aluminum. Indeed, you have to do that to
                        weld it. And it will remain rust free for as long as milliseconds.
                        Which is why the flux for aluminum welding is designed to keep oxygen
                        from reaching the aluminum, rather than taking the rust off in the
                        first place, like copper flux is designed to do.
                        If you take two sheets of Aluminum foil, clean them well, and lay them
                        on top of one another, they are electrically insulated, because the
                        rust layer, a good insulator, forms so quickly. This is the basis of
                        Aluminum Electrolyte Capacitors.
                        For an example of how aggressive Aluminum is at oxygenating, go to
                        Youtube, and look up Thermite. My personal favorite is 'Thermite and
                        Ice explosion'. The burning Aluminum is hot enough to split the
                        Hydrogen/Oxygen bond of water, creating a nice little cloud of VERY
                        explosive gas.

                        --- In loopantennas@yahoogroups.com, Richards <jruing@...> wrote:
                        >
                        > I cannot see any advantage to putting a wire inside a copper loop as
                        you
                        > suggest. The signal would be picked up on the copper loop which would,
                        > I think, shield the wire inside -- consider = if thin gauge coaxial
                        > cable braid shields the inner conductor on coax cable, then certainly
                        > the copper tubing would shield any wire inside it from receiving any
                        signal.
                        >
                        > Just my take
                        >
                        > Happy Trails and 73. ///// Richards - KD8JHR /////
                        > ====================================================
                        >
                        > jefeickert wrote:
                        > > If I were to make a loop antenna like Wellbrook type , using
                        copper tubing and
                        > > also running a wire inside the tube as well?
                        > > JIM F.
                        > >
                        >
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