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References on passive broadband small loops

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  • pu3hag.l@gmail.com
    Hello, I m planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It d be used for reception in LF
    Message 1 of 7 , Jun 5, 2014
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      Hello,

      I'm planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It'd be used for reception in LF and MF bands.

      I was checking the web and found diagrams and notes recommending step up transformer ranging from 1:10 to 1:100.

      Would you recall any references discussing this type of loop and the needed step up xmfr?

      All tips and suggestions are welcome!

      Thank you,

      -- pu3hag huelbe

      Sent from my iPhone
    • Andy
      I don t have references handy. But I think the reason for the step-up transformer, is because the small loop has an exceedingly low radiation resistance, and
      Message 2 of 7 , Jun 5, 2014
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        I don't have references handy.  But I think the reason for the step-up transformer, is because the small loop has an exceedingly low radiation resistance, and one gets better power transfer with the step-up XFMR.  You get the most power transfer from antenna to receiver when you have a conjugate impedance match, and the step-up comes closer to matching the real component.  If there is also a tuning capacitor in there, that might also help, but maybe not necessary for an RX-only antenna.

        On LF and MF, maximum power transfer (a perfect match) is not needed because background noise tends to dominate.  (i.e., more signal from the antenna does not give you more S/N.)  But if the mismatch is too great, the received signal may be so low that the S/N suffers.  So the XFMR helps with that.

        That'd be my guess.

        Regards,
        Andy


      • Maxwell Mclellan
        Greetings from vk2tti, Is the loop to be * single or multi turn or * tuned with capacitor? with regards. Sent from my iPad
        Message 3 of 7 , Jun 5, 2014
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          Greetings from vk2tti,
          Is the loop to be
          * single or multi turn or
          * tuned with capacitor?
          with regards.

          Sent from my iPad

          On 6 Jun 2014, at 3:53 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

           

          Hello,

          I'm planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It'd be used for reception in LF and MF bands.

          I was checking the web and found diagrams and notes recommending step up transformer ranging from 1:10 to 1:100.

          Would you recall any references discussing this type of loop and the needed step up xmfr?

          All tips and suggestions are welcome!

          Thank you,

          -- pu3hag huelbe

          Sent from my iPhone

        • pu3hag.l@gmail.com
          Hi Max. It d be a single turn, 1 meter diameter or a bit more, untuned. The loop terminal would be connected to a step up xmfr. Sent from my iPhone On Jun 6,
          Message 4 of 7 , Jun 5, 2014
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            Hi Max. It'd be a single turn, 1 meter diameter or a bit more, untuned. The loop terminal would be connected to a step up xmfr. 

            Sent from my iPhone

            On Jun 6, 2014, at 3:25 AM, "Maxwell Mclellan vk2tti@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

             

            Greetings from vk2tti,
            Is the loop to be
            * single or multi turn or
            * tuned with capacitor?
            with regards.

            Sent from my iPad

            On 6 Jun 2014, at 3:53 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

             

            Hello,

            I'm planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It'd be used for reception in LF and MF bands.

            I was checking the web and found diagrams and notes recommending step up transformer ranging from 1:10 to 1:100.

            Would you recall any references discussing this type of loop and the needed step up xmfr?

            All tips and suggestions are welcome!

            Thank you,

            -- pu3hag huelbe

            Sent from my iPhone

          • pu3hag.l@gmail.com
            Thank you for the insights, Andy! Sent from my iPhone On Jun 6, 2014, at 3:17 AM, Andy ai.egrps@gmail.com [loopantennas]
            Message 5 of 7 , Jun 5, 2014
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              Thank you for the insights, Andy!

              Sent from my iPhone

              On Jun 6, 2014, at 3:17 AM, "Andy ai.egrps@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

               

              I don't have references handy.  But I think the reason for the step-up transformer, is because the small loop has an exceedingly low radiation resistance, and one gets better power transfer with the step-up XFMR.  You get the most power transfer from antenna to receiver when you have a conjugate impedance match, and the step-up comes closer to matching the real component.  If there is also a tuning capacitor in there, that might also help, but maybe not necessary for an RX-only antenna.

              On LF and MF, maximum power transfer (a perfect match) is not needed because background noise tends to dominate.  (i.e., more signal from the antenna does not give you more S/N.)  But if the mismatch is too great, the received signal may be so low that the S/N suffers.  So the XFMR helps with that.

              That'd be my guess.

              Regards,
              Andy


            • Maxwell Mclellan
              G day again, I would suggest that you construct a temporary transformer using a split ferrite clip on device. Used to clamp on cables for interference
              Message 6 of 7 , Jun 5, 2014
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                G'day again, I would suggest that you construct a temporary transformer using a split ferrite clip on device. Used to clamp on cables for interference reduction. It is much easier to wind different ratios on a split ferrite than on a toroid type. However, I think you might be disappointed with the results from a single turn loop. Give it a go by all means. Regards again Max vk2tti.



                Sent from my iPad
                 
                On 6 Jun 2014, at 4:32 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                 

                Hi Max. It'd be a single turn, 1 meter diameter or a bit more, untuned. The loop terminal would be connected to a step up xmfr. 

                Sent from my iPhone

                On Jun 6, 2014, at 3:25 AM, "Maxwell Mclellan vk2tti@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                 

                Greetings from vk2tti,
                Is the loop to be
                * single or multi turn or
                * tuned with capacitor?
                with regards.

                Sent from my iPad

                On 6 Jun 2014, at 3:53 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                 

                Hello,

                I'm planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It'd be used for reception in LF and MF bands.

                I was checking the web and found diagrams and notes recommending step up transformer ranging from 1:10 to 1:100.

                Would you recall any references discussing this type of loop and the needed step up xmfr?

                All tips and suggestions are welcome!

                Thank you,

                -- pu3hag huelbe

                Sent from my iPhone

              • pu3hag.l@gmail.com
                Thank you Max! Split cores are a brilliant idea! Huelbe Sent from my iPhone On Jun 6, 2014, at 3:45 AM, Maxwell Mclellan vk2tti@optusnet.com.au
                Message 7 of 7 , Jun 6, 2014
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                  Thank you Max! Split cores are a brilliant idea! Huelbe

                  Sent from my iPhone

                  On Jun 6, 2014, at 3:45 AM, "Maxwell Mclellan vk2tti@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                   

                  G'day again, I would suggest that you construct a temporary transformer using a split ferrite clip on device. Used to clamp on cables for interference reduction. It is much easier to wind different ratios on a split ferrite than on a toroid type. However, I think you might be disappointed with the results from a single turn loop. Give it a go by all means. Regards again Max vk2tti.



                  Sent from my iPad
                   
                  On 6 Jun 2014, at 4:32 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                   

                  Hi Max. It'd be a single turn, 1 meter diameter or a bit more, untuned. The loop terminal would be connected to a step up xmfr. 

                  Sent from my iPhone

                  On Jun 6, 2014, at 3:25 AM, "Maxwell Mclellan vk2tti@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                   

                  Greetings from vk2tti,
                  Is the loop to be
                  * single or multi turn or
                  * tuned with capacitor?
                  with regards.

                  Sent from my iPad

                  On 6 Jun 2014, at 3:53 pm, "'pu3hag.l@...' pu3hag.l@... [loopantennas]" <loopantennas@yahoogroups.com> wrote:

                   

                  Hello,

                  I'm planning to experiment with a small loop (circular shape, 1 meter dia) passively connected to the 50R feed line. It'd be used for reception in LF and MF bands.

                  I was checking the web and found diagrams and notes recommending step up transformer ranging from 1:10 to 1:100.

                  Would you recall any references discussing this type of loop and the needed step up xmfr?

                  All tips and suggestions are welcome!

                  Thank you,

                  -- pu3hag huelbe

                  Sent from my iPhone

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