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70203Re: [softrock40] Antenna problems?

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  • Alan
    Nov 19, 2012
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      Ulf,

      http://websdr.ewi.utwente.nl:8901/ ?

      This is mounted on top of the building.
      A quick search:- "When you place this tiny antenna outside the house (!), it will perform like a full-sized antenna for the VLF and
      shortwave bands."

      It is , as far as I can see, dependent on being placed away from interference sources. Then the amplified signal fed to the
      receiver.
      I find antennas like this work well on LF. But mine are 30m away from any building. Mounted close they are ineffective, picking up
      noise from many sources.

      You need something with minimal response to interference.

      73 Alan G4ZFQ


      ----- Original Message -----
      From: "Ulf Holt Gmail" <ulf.holt@...>
      To: <softrock40@yahoogroups.com>
      Sent: Monday, November 19, 2012 6:18 AM
      Subject: Re: [softrock40] Antenna problems?


      I have been informed by a Norwegian Amateur about a mini antenna Pa0rdt-mini-whip, which sounds interesting, there is an URL to a
      SDR radio using this antenna? Http://Webster.ewi.utwente.nl:8901 and it was impressing what this little mini antenna could do. This
      is, of course, an antenna for RX only, so I will give it a go. Anyone out there with experience?


      > There are a number of DOS and Windows loop calculation applications like mloop31, loopcalc.exe, RJELOOP1, etc. available via a
      > search engine.
      > With the programs you can model a loop - by providing loop size (total length), diameter of coax and frequency it will give values
      > of capacitors, etc.
      >
      > Online loop calculator http://www.66pacific.com/calculators/small_tx_loop_calc.aspx
      >
      > RG213 is best as the self capacitance is much less than RG58 and higher Q.
      >
      > Also practical articles - so many as to make your head spin.
      > http://www.rsars.org.uk/ELIBRARY/ANTENNAS%20DOCS/Portable%20HF%20Loop%20%2040-10m%20-%20G8ODE%20iss%201.3%20.pdf
      >
      > http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.antenna/2006-08/msg00069.html
      >
      > I am sure you can build a loop that's easily transportable to cover all HF bands 40m - 10m.
      >
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