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Do parasitic elements work with small magloops to increase directionality (gain)

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  • tom_in_van
    It s a well known fact that the gain from a dipole antenna can be varied by adding or removing parasitic director/reflector elements --- would parasitic
    Message 1 of 5 , Apr 15, 2006
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      It's a well known fact that the gain from a dipole antenna can be
      varied by adding or removing parasitic director/reflector elements ---
      would parasitic elements have similar effects on a small, magnetic
      loop antenna? I've done a fair amount of googling on the subject of
      small, magloops and I don't think I've ever seen anyone address this
      question.
      I hope to have more time to do my own experimenting in the near
      future, but in the meantime I was just wondering if anyone was aware
      of any attempts to increase the directionality of a small, magloop by
      means of parasitic elements.

      73 from Vancouver
      :)

      Tom
    • dldorrance
      ... Hi Tom, I am not an an expert in this area, but I have asked this very question to an EE knowledgeable about antennas. The answer is no. Apparently the
      Message 2 of 5 , Apr 15, 2006
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        --- In loopantennas@yahoogroups.com, "tom_in_van" <cyberhun@...> wrote:
        >
        > It's a well known fact that the gain from a dipole antenna can be
        > varied by adding or removing parasitic director/reflector elements ---
        > would parasitic elements have similar effects on a small, magnetic
        > loop antenna? I've done a fair amount of googling on the subject of
        > small, magloops and I don't think I've ever seen anyone address this
        > question.
        > I hope to have more time to do my own experimenting in the near
        > future, but in the meantime I was just wondering if anyone was aware
        > of any attempts to increase the directionality of a small, magloop by
        > means of parasitic elements.
        >
        > 73 from Vancouver
        > :)
        >
        > Tom
        >

        Hi Tom,

        I am not an an expert in this area, but I have asked this very
        question to an EE knowledgeable about antennas. The answer is no.
        Apparently the only way several small loops can be hooked together for
        gain purposes would be through a phasing line.

        Dave WA6YSO
      • Jim Dunstan
        ... Hi Tom, It is possible to do some interesting things with 2 small receiving loops but I am unaware of any experimentation with multiple small transmitting
        Message 3 of 5 , Apr 16, 2006
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          At 12:39 AM 16/04/2006 +0000, you wrote:
          >It's a well known fact that the gain from a dipole antenna can be
          >varied by adding or removing parasitic director/reflector elements ---
          >would parasitic elements have similar effects on a small, magnetic
          >loop antenna? I've done a fair amount of googling on the subject of
          >small, magloops and I don't think I've ever seen anyone address this
          >question.
          >I hope to have more time to do my own experimenting in the near
          >future, but in the meantime I was just wondering if anyone was aware
          >of any attempts to increase the directionality of a small, magloop by
          >means of parasitic elements.
          >
          >73 from Vancouver
          >:)
          >
          >Tom

          Hi Tom,

          It is possible to do some interesting things with 2 small receiving loops
          but I am unaware of any experimentation with multiple small transmitting
          loops. For example placing 2 small loops at right angles to each
          other will allow remote 'sweeping' of the bi-directional properties
          without physically moving the loops. With the addition of a
          non-directional antenna (vertical) it is possible to get a uni-directional
          effect ... again this can be done remotely.

          I also find that placing 2 small tuned loops side by side seems to narrow
          the bandwidth (increase Q .. ??). It would be interesting to experiment
          with transmitting applications.

          Jim
        • Andy
          ... Interesting question. Parasitic element means they are passive and not connected in any way to the feedline. (As others have said, you can do interesting
          Message 4 of 5 , Apr 16, 2006
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            > It's a well known fact that the gain from a dipole antenna can be
            > varied by adding or removing parasitic director/reflector elements ---
            > would parasitic elements have similar effects on a small, magnetic
            > loop antenna? I've done a fair amount of googling on the subject of
            > small, magloops and I don't think I've ever seen anyone address this
            > question.

            Interesting question.

            Parasitic element means they are passive and not connected in any way to
            the feedline. (As others have said, you can do interesting things with
            arrays of two or more driven or combined loops, but that's a different
            ballgame.)

            Generally, parasitic elements are some distance (a tenth of a wavelength or
            more) from the main or driven element. I think the problem with small
            magnetic loops is that they have just too little effect on the surrounding
            electromagnetic field when you get some distance away from them. For a
            parasitic loop to affect the field that far away, it's got to be a sizeable
            loop, on the order of a full wave loop. I think.

            If you put a small parasitic loop close to the main magloop, it will change
            its characteristics, but I'm not sure it can improve its directionality.
            Narrowing an antenna's beamwidth generally requires physical size (e.g.,
            yagi length). I'm not sure it can be done with a small size.

            Regards,
            Andy
          • wuethrich_christian
            Hi Tom, I think that there are two main difficulties making what you suggest impossible: In the case of reflectors or directors mounted on a dipole, we speak
            Message 5 of 5 , Apr 23, 2006
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              Hi Tom,

              I think that there are two main difficulties making what you suggest
              impossible:

              In the case of reflectors or directors mounted on a dipole, we speak
              of dimension of 1/2 or 1/4 of the wavelength with a clear far field.
              We also speak of oscillating E field. The magnetic loop is much
              smaller (typically 1/16 of the wavelength or less) and we speak of an
              oscillatimng magnetic field.

              The second difficulty is the quality factor of the magnetic loop and
              the amount of power dissipated in the loop respective to the amount
              that is radiated. In the case of a Yagi, the power dissipated in the
              reflector or directors is weak, this is not the case in a resonnating
              loop that stores a lot of energy before radiating it in space.

              As mentionned, playing with the phase of the elements of an array of
              loops would allow to steer the emitted wave.

              I hope this brings some light in this field.

              73 to all.

              --- In loopantennas@yahoogroups.com, "tom_in_van" <cyberhun@...> wrote:
              >
              > It's a well known fact that the gain from a dipole antenna can be
              > varied by adding or removing parasitic director/reflector elements ---
              > would parasitic elements have similar effects on a small, magnetic
              > loop antenna? I've done a fair amount of googling on the subject of
              > small, magloops and I don't think I've ever seen anyone address this
              > question.
              > I hope to have more time to do my own experimenting in the near
              > future, but in the meantime I was just wondering if anyone was aware
              > of any attempts to increase the directionality of a small, magloop by
              > means of parasitic elements.
              >
              > 73 from Vancouver
              > :)
              >
              > Tom
              >
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