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3271RE: [loopantennas] Re: Looking for 3 band receiving loop...

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  • David Atkins
    Apr 1, 2007

      I, for one would be very interested to see your loop design

      -----Original Message-----
      From: loopantennas@yahoogroups.com
      [mailto:loopantennas@yahoogroups.com]On Behalf Of gplynas
      Sent: 01 April 2007 15:19
      To: loopantennas@yahoogroups.com
      Subject: [loopantennas] Re: Looking for 3 band receiving loop...

      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.
      Paul Lynas
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