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Re: [loopantennas] FW: Loop on roof or in garden?

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  • Göran Norstedt
    I have tried both, and I have also asked around for advice and best practice. The advice I have been given is that the best location depends on mainly two
    Message 1 of 7 , Oct 4, 2013
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      I have tried both, and I have also asked around for
      advice and best practice.
      The advice I have been given is that the best location
      depends on mainly two things:
      1. Frequency of choice
      2. Type of local desturbances experienced

      Me, being a LW, NDB and MW- buff with lots of local urban electrical disturbances from PSU, TV-sets, etc, I settled for the ground mounted. This gives me the least amount of disturbances going into the loop, because the soil screens a big part of the circumference of the loop, the bottom part. :)
      The higher the ferquency you want to cover, the more the loop
      benefits from a high altitude. Bear also in mind that loops are
      more directional at lower frequencies.
      You guys, building two loops, have the golden opportunity. Place
      yours in the garden and your buddy's on the roof and try out
      best practice for your own needs.
      Good luck, and dont forget to build a yourseves good, low noise amps. Loops arent whichcraft by any kind, small antennas generate lesser signals than big, by comparison.

      73 de Göran

      Göran Norstedt
      SM7IYM at JO65mq
      Lomma, SWE

      +4640412213
      +46709374909

      4 okt 2013 kl. 12:06 skrev "dx11" <dx11@...>:

       

       

      With a friend I am in the process of building a magnetic unturned active loop of about 1 meter diameter for each of us for general and ham band listening.

      I have often seen remarks that these loops perform best at a  few meters above ground level.

      Has anyone got any experience with the use of this type of antenna on a rooftop.

      We have the option of placing this antenna on the flat concrete roof of a flat building of about 30 meters height, any advice?

      How would this compare with the positioning of this same antenna on the balcony railing somewhat lower?

       

      I hope someone can fill in the voids in my own experience.

       

      Cor Beijersbergen

    • winston376
      Cor, For receive only, I performed some experiments a few years ago with a 2 meter diameter untuned loop consisting of 1/2 inch water copper pipe and
      Message 2 of 7 , Oct 5, 2013
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        Cor,


        For receive only, I performed some experiments a few years ago  with a 2 meter diameter untuned loop consisting of  1/2 inch water copper pipe and minicircuits balun(s) interfacing to the coaxial cable. Cable(75 ohm RG-6 Quad shielding)  had large  ferrite beads or alternatively, multiturns on large diameter  toroids at both ends.   Outside of the house at ground level,  rooftop, and on a 12 meter tower. Main concern was the EMI emissions from TV's, PC's flourescent lights etc. in a suburban high density housing tract.


        For EMI, it was worse at ground level  (2-5 meters from the house). Less EMI on the rooftop (5 meters above ground)  and least EMI on the tower. That was LF through 30 MHz.


        As far as signal strength of LF beacons and  local MW broadcasters, the signal strength was  best at ground level measured at about  2-6 dB higher than at the tower elevation.....however, the EMI was also much higher.   For  SW above about 4-8 MHz,  signal strength of ham and broadcasters  was higher on the rooftop as well as even higher on the tower.



        Hope this helps


        Alex



        ---In loopantennas@yahoogroups.com, <loopantennas@yahoogroups.com> wrote:

         

        With a friend I am in the process of building a magnetic unturned active loop of about 1 meter diameter for each of us for general and ham band listening.

        I have often seen remarks that these loops perform best at a  few meters above ground level.

        Has anyone got any experience with the use of this type of antenna on a rooftop.

        We have the option of placing this antenna on the flat concrete roof of a flat building of about 30 meters height, any advice?

        How would this compare with the positioning of this same antenna on the balcony railing somewhat lower?

         

        I hope someone can fill in the voids in my own experience.

         

        Cor Beijersbergen

      • dx11
        Hello Göran, Does it means that you advise to put the antenna high on the roof instead of somewhat lower on the balcony? We will certainly compare the two
        Message 3 of 7 , Oct 7, 2013
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          Hello Göran,

           

          Does it means that you advise to put the antenna high on the roof instead of somewhat lower  on the balcony?

           

          We will certainly compare the two situations after completion of our loops.

           

          The amplifier we will use is not decided yet, I’m going through all the designs I have been able to find up to now. I do not have an education in electronics so I have to rely on what others mention about the subject.

           

          Thanks for your reaction.

           

          Cor Beijersbergen

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