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Define loop antenna

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  • Bill Boyd
    Hi All I m new to the group and have a question. If I run a wire around the outside of my house totalling about 130 to 140 feet is that a loop antenna. Or does
    Message 1 of 6 , Aug 19, 2006
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      Hi All
      I'm new to the group and have a question. If I run a wire around the
      outside of my house totalling about 130 to 140 feet is that a loop
      antenna. Or does it have to be vertical? I have a small lot and not
      much room for long wire. I am trying to figure our the best low noise
      antenna in a high electrical noise heighborhood environment. My back
      yard has three different house feeds running across it and my front
      yard is about 20 feet deep, so the roof is about the only place to run
      an antenna. Any help is greatly appreciated.
      Thanks
      Bill Boyd
    • Anders
      ... Hello Bill! Check this site: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3274 /Anders
      Message 2 of 6 , Aug 19, 2006
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        --- In loopantennas@yahoogroups.com, "Bill Boyd" <wboyd530@...> wrote:
        >
        > Hi All
        > I'm new to the group and have a question. If I run a wire around the
        > outside of my house totalling about 130 to 140 feet is that a loop
        > antenna. Or does it have to be vertical? I have a small lot and not
        > much room for long wire. I am trying to figure our the best low noise
        > antenna in a high electrical noise heighborhood environment. My back
        > yard has three different house feeds running across it and my front
        > yard is about 20 feet deep, so the roof is about the only place to run
        > an antenna. Any help is greatly appreciated.
        > Thanks
        > Bill Boyd
        >

        Hello Bill!
        Check this site:
        http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3274

        /Anders
      • Jim Dunstan
        ... Hi Bill, A loop is a loop no matter what its orientation .... eg vertical, horizontal, or something in between. Since we are talking definition .... there
        Message 3 of 6 , Aug 19, 2006
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          At 05:56 PM 19/08/2006 +0000, you wrote:

          >Hi All
          >I'm new to the group and have a question. If I run a wire around the
          >outside of my house totalling about 130 to 140 feet is that a loop
          >antenna. Or does it have to be vertical? I have a small lot and not
          >much room for long wire. I am trying to figure our the best low noise
          >antenna in a high electrical noise heighborhood environment. My back
          >yard has three different house feeds running across it and my front
          >yard is about 20 feet deep, so the roof is about the only place to run
          >an antenna. Any help is greatly appreciated.
          >Thanks
          >Bill Boyd

          Hi Bill,

          A loop is a loop no matter what its orientation .... eg vertical,
          horizontal, or something in between. Since we are talking definition ....
          there are few basic categories into which all antennas fit. First there is
          what is called a dipole antenna .... eg it is a wire in space with 2
          separate ends along which antenna currents flow. This wire in space can be
          coupled to your radio/transmitter by a feed line that is located in the
          center (center fed dipole) or at the end (end fed dipole), or somewhere in
          between.

          Now, if you take that dipole and join the ends together to form a loop then
          you will have a loop antenna. Both antennas are what are called 'balanced'
          antennas .... that is the RF currents are running within the antenna and
          not between the antenna and ground (or at least you hope that is the
          case). These two types of antennas which are balanced are in contrast to
          the last category which you can call a 'monopole' antennas.

          Monopole antennas are not 'balanced' .... one end of the antenna is
          connected to ground (earth) and the other end is (usually) perpendicular to
          the earth. The antenna currents flow from one end of the wire to earth
          and back and therefore are not 'balanced'. Most of these kinds of antennas
          are called 'verticals' eg the most efficient direction to run the antenna !!

          All antennas are designs based on the 3 possible configurations, the
          dipole, the loop, or the vertical (and sometimes one is mistaken for the
          other).

          Now designing the antenna for minimum received RFI (noise) is another
          matter not necessarily related to choosing between loop, dipole, or vertical.

          Jim
        • davis gates
          ... run ... Bill That is a loop antenna. Yours would be called a long wire loop since it is a significant fraction of a wavelength long. These are highly
          Message 4 of 6 , Aug 20, 2006
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            --- In loopantennas@yahoogroups.com, "Bill Boyd" <wboyd530@...> wrote:
            >
            > Hi All
            > I'm new to the group and have a question. If I run a wire around the
            > outside of my house totalling about 130 to 140 feet is that a loop
            > antenna. Or does it have to be vertical? I have a small lot and not
            > much room for long wire. I am trying to figure our the best low noise
            > antenna in a high electrical noise heighborhood environment. My back
            > yard has three different house feeds running across it and my front
            > yard is about 20 feet deep, so the roof is about the only place to
            run
            > an antenna. Any help is greatly appreciated.
            > Thanks
            > Bill Boyd
            >

            Bill
            That is a loop antenna. Yours would be called a "long wire loop" since
            it is a significant fraction of a wavelength long.
            These are highly efficient antennas. I use one for transmitting and
            receiving low band DX. It has a low angle of radiation (and reception)
            on the second harmonic. The primary frequency has too much near
            vertical radiation and reception to be of much use except for local
            communications.
            You will need a tuner.
            A good discussion of these antennas is in the magazine "World Radio" in
            several issues, summer 2005.
            Hope this helps.
            Dave Ag4K
          • dldorrance
            ... definition .... ... there is ... can be ... somewhere in ... loop then ... balanced ... and ... contrast to ... perpendicular to ... earth ... antennas
            Message 5 of 6 , Aug 20, 2006
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              --- In loopantennas@yahoogroups.com, Jim Dunstan <jdunstan@...> wrote:
              >
              > At 05:56 PM 19/08/2006 +0000, you wrote:
              >

              >
              > Hi Bill,
              >
              > A loop is a loop no matter what its orientation .... eg vertical,
              > horizontal, or something in between. Since we are talking
              definition ....
              > there are few basic categories into which all antennas fit. First
              there is
              > what is called a dipole antenna .... eg it is a wire in space with 2
              > separate ends along which antenna currents flow. This wire in space
              can be
              > coupled to your radio/transmitter by a feed line that is located in the
              > center (center fed dipole) or at the end (end fed dipole), or
              somewhere in
              > between.
              >
              > Now, if you take that dipole and join the ends together to form a
              loop then
              > you will have a loop antenna. Both antennas are what are called
              'balanced'
              > antennas .... that is the RF currents are running within the antenna
              and
              > not between the antenna and ground (or at least you hope that is the
              > case). These two types of antennas which are balanced are in
              contrast to
              > the last category which you can call a 'monopole' antennas.
              >
              > Monopole antennas are not 'balanced' .... one end of the antenna is
              > connected to ground (earth) and the other end is (usually)
              perpendicular to
              > the earth. The antenna currents flow from one end of the wire to
              earth
              > and back and therefore are not 'balanced'. Most of these kinds of
              antennas
              > are called 'verticals' eg the most efficient direction to run the
              antenna !!
              >
              > All antennas are designs based on the 3 possible configurations, the
              > dipole, the loop, or the vertical (and sometimes one is mistaken for
              the
              > other).
              >
              > Now designing the antenna for minimum received RFI (noise) is another
              > matter not necessarily related to choosing between loop, dipole, or
              vertical.
              >
              > Jim
              >

              Bill, to add to Jim's explanation it is useful to expand on the
              polarization vs near field noise issue, as you outlined noise as a
              reason to use a loop antenna on your small lot. As an aside, I
              sympathize with your problem, as my small lot has power line easements
              on 2 sides making it very noisy.

              The loop you describe, although parallel to the ground, is vertically
              polarized as loop polarization is opposite dipole polarization. Man
              made noise is principally vertically polarized. This means your loop
              will not decrease locally generated noise.

              As a start, you might do better by stringing a dipole around the
              house, whether resonant or not, as the dipole would tend to reject
              noise better than a loop similarly situated.

              There is a caveat here. If either type of antenna above is under 1/2
              wavelength from the earth, the angle of radiation will be high,
              diminishing ability to receive and/or transmit to distant stations.

              A better solution would be a horizontally polarized loop, that is, one
              whose plane is perpendicular to the earth. That way the polarization
              diminishes the noise and as a bonus you may rotate the loop to null
              the noise. Furthermore, this type of loop works well under 1/2
              wavelength above the earth.

              Because of size constraints of your property, a small, horizontally
              polarized loop might be ideal, though more complicated to construct.
              The construction depends upon the purpose of the loop, as receive-only
              small loops have different requirements than transmit-receive small loops.

              Dave WA6YSO
            • Bill Boyd
              Thanks to all that answered my request. I Think I will like being a part of this group. I probably should have been a little clearer in my request. I was
              Message 6 of 6 , Aug 20, 2006
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                Thanks to all that answered my request. I Think I will like being a part of this group. I probably should have been a little clearer in my request. I was mainly worried about not picking up electrical noise. I've been around short wave off and on for 40 years. never did study it much, just enjoyed listening. Now I,m co-owner of scanner talk on Yahoo and we are getting into HF military monitoring. My old DX-440 didn't quite cut the mustard here in the midwest so i picked up a IC-R75 Icom and love it. Ijust need a good antenna on a small lot. Not much to ask. Right? Ya, I know. People in heck want ice water to. Oh ya, did I mention cheap. I definatly need cheap. Well as usual i've rambled on to much again. But again thanks.
                Bill B


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