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3269Re: [loopantennas] Re: Looking for 3 band receiving loop...

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  • c.e.boyd
    Apr 1, 2007
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      Hi Paul: Do you recall the values for the coil and caps you used for this LW
      antenna? Also to modify this antenna for the low freq ham bands, (not 60)
      what would be the necessary values? Thanks: theboyd
      ----- Original Message -----
      From: "gplynas" <gplynas@...>
      To: <loopantennas@yahoogroups.com>
      Sent: Sunday, April 01, 2007 8:19 AM
      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.
      > Regards,
      > Paul Lynas
      > WA5LFY
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