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3268Re: Looking for 3 band receiving loop...

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  • gplynas
    Apr 1, 2007
      Hi Steve,
      Many years ago I designed a broadband loop for monitoring
      radio-navigation beacons which had to cover the frequency range of 195
      kHz to 480 kHz. Our previous loops were tuned single-frequency. I
      designed this one by looking at the loop as the "inductor" in a Pi
      network, with a transformation ratio from (radiation resistance + loss
      resistance) to the input impedance of the amplifier, and with a
      break-point above the highest frequency. I fed this into an FET
      amplifier with high input impedance. A resistor of about 10k
      furnished a return to ground at the amplifier input and stabilized the
      gain. The whole circuit was then feed with +15 VDC through the coax
      from the receiver.

      This worked well, with a response that was reasonably flat over more
      than 2 octaves. I think the same concept could be used from 160M to
      40M. By design, I was able to reject the broadcast band signals which
      could overload a broadband design.
      Regards,
      Paul Lynas
      WA5LFY

      --- In loopantennas@yahoogroups.com, "n6vl" <n6vl@...> wrote:
      >
      > Hi,
      >
      > I am looking for a receiving loop I can use on the 160, 80, and 40
      > meters ham bands. It can be either an indoor loop in my ham shack. Or
      > it can be a larger outdoor one. I hope to find one I can use on all the
      > lower HF ham bands. Many designs are for single band. Perhaps there is
      > a design on posted on this group I simply haven't noticed.
      >
      > Thanks in advance!
      >
      > Steve N6VL
      >
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