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Re: Half Loop Mag Mobile Antenna

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  • Gian
    Thanks for your rely. Yes, I did visit that site. The only problem is to understand how the half a loop works, i.e. what happen to RF currents un the mirror
    Message 1 of 17 , Jun 24, 2013
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      Thanks for your rely.

      Yes, I did visit that site. The only problem is to understand how the half a loop works, i.e. what happen to RF currents un the mirror part of the loop and on the car real roof.

      I will try to figure out the capacitor formula from the 14-30MHz example.

      Thanks and best 73

      Gian
      I7SWX

      --- In loopantennas@yahoogroups.com, "va3ae" <va3ae@...> wrote:
      >
      > If you have not seen this already it might provide food for thought.
      > <http://www.laud.no/la6nca/loop/>
      >
      > 73 de va3ae
      >
    • Andy
      ... For a half loop that connects to the roof on both ends, at the very least you have the loop current itself which completes its circuit via the roof. There
      Message 2 of 17 , Jun 24, 2013
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        Gian <i7swx@...> wrote:

        > ... i.e. what happen to RF currents un the mirror part of the loop and on
        > the car real roof.

        For a half loop that connects to the roof on both ends, at the very
        least you have the loop current itself which completes its circuit via
        the roof. There would be some spreading out of the current in the
        roof, depending on frequency, I suppose.

        Many mobile loops are complete loops that happen to rest slightly
        above the roof. That's a good question what happens in the roof in
        that case. I bet it depends a lot on loop orientation. Most of these
        small mobile loops are vertically oriented, but I have seen horizontal
        loops above the roof too. It would seem like the roof causes a
        "shorted turn" that is close coupled to the loop, which is probably
        not good.

        Regards,
        Andy
      • Gian
        Hi Andy, ... I have a two bars roof rack across it (add-on). Would it be necessary to connect the loop mirror side to it or isolate it as strong current may
        Message 3 of 17 , Jun 26, 2013
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          Hi Andy,

          --- In loopantennas@yahoogroups.com, Andy <ai.egrps@...> wrote:
          >
          > Gian <i7swx@...> wrote:
          >
          > > ... i.e. what happen to RF currents un the mirror part of the loop and on
          > > the car real roof.
          >
          > For a half loop that connects to the roof on both ends, at the very
          > least you have the loop current itself which completes its circuit via
          > the roof. There would be some spreading out of the current in the
          > roof, depending on frequency, I suppose.

          >
          > Many mobile loops are complete loops that happen to rest slightly
          > above the roof. That's a good question what happens in the roof in
          > that case. I bet it depends a lot on loop orientation. Most of these
          > small mobile loops are vertically oriented, but I have seen horizontal
          > loops above the roof too. It would seem like the roof causes a
          > "shorted turn" that is close coupled to the loop, which is probably
          > not good.

          I have a two bars roof rack across it (add-on). Would it be necessary to connect the loop mirror side to it or isolate it as strong current may spread ???


          Best 73

          Gian
          >
          > Regards,
          > Andy
          >
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