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Date: Mon, 15 Aug 2011 20:23:58 +0200
From: wolf_dl4yhf <dl4yhf@freenet.de>
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References: <68BE37BD69E54DEE89CEBA8E30E9B94E@PcMinto> <4E47FFE9.10100@iup.uni-heidelberg.de> <3ED8E5422F1F45DBB8186E9D9870AD63@PcMinto> <4E480E02.9020706@iup.uni-heidelberg.de> <938BF599006244949F6CDDB5BA91F347@PcMinto> <4E482FBD.7030402@freenet.de> <4E484183.9090805@iup.uni-heidelberg.de> <4E494A57.90105@freenet.de> <4E4956DA.1060201@iup.uni-heidelberg.de>
In-Reply-To: <4E4956DA.1060201@iup.uni-heidelberg.de>
Subject: Re: LF: Ferrite RX antennas
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Hi Stefan,

For a resonant design (tuned with parallel capacitor) I'd use the litz 
wire. For the broadband design (terminated with a low-Z amplifier) it 
shouldn't matter too much, but 0.5 mm wire diameter would be the 
minimum. The thinner the wire, the larger the 'R', R is noisy, and we 
don't want noise ;-)

7 rods in a bundle, and two of these bundles sound good. But it depends 
on the material (permeability) if it makes sense to use 8 "parallel" 
rods - consider this: one single rod may already 'attract' enough 
magnetic field lines from the far field; 7 rods will not attract 7 times 
as much ! Anyway for backpack operation you don't have the choice to 
build a meter-long rod like Lubos' large antenna.

Beware that my crossed-loop antenna was built for VLF, not LF.

Cheers,
     Wolf .


Am 15.08.2011 19:26, schrieb Stefan Schäfer:
> Hello Wolf,
>
> Thanks to the link to your nice to read article. I just found it a 
> hour before your mail and already read it ;-)
>
> Well, i also prefer the usual configuration instead of that sleeve 
> antenna. Also i have to keep the focus on my actual goal: Making a 
> handy antenna for amateur LF / p operation without a car! And the 16 
> rods i will get (14 cm long, 8mm diameter) will be best in a 2x7 
> config. i think. Or do you rather suggest 3x5 or even 4x4?
> 2x7 is then about 30 cm long which is very fine for a backpack and 
> should be robust enough.
> I would use the same double side bonding tape, this is very useful to 
> get a first fixed arrangement. Then putting all that in a PVC tube, 
> 2mm thickness and add the turns above the tube.
> Would you recommend litz wire or standard 0.5 mm enamelled wire?
> As an E field shield i would use aluminium bonding tape, without 
> making a shutcut turn of course.
>
> So the newcomers should not think that this antenna is the best what 
> one can use for LF. Just in that special case of /p i see advantages. 
> Otherwise a well designed loop (+ preamp or a very sensitive RX, if a 
> samll loop is used) or E field antenna such as the PA0RDT should be 
> preferred, as Alan already pointed out.
>
> Looking forward to a direct comparison of the DCF39 SNR that can be 
> achieved and to the first amateur signal received with that antenna in 
> /p...
>
> 73, Stefan/DK7FC
>


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    Hi Stefan,<br>
    <br>
    For a resonant design (tuned with parallel capacitor) I'd use the
    litz wire. For the broadband design (terminated with a low-Z
    amplifier) it shouldn't matter too much, but 0.5 mm wire diameter
    would be the minimum. The thinner the wire, the larger the 'R', R is
    noisy, and we don't want noise ;-)<br>
    <br>
    7 rods in a bundle, and two of these bundles sound good. But it
    depends on the material (permeability) if it makes sense to use 8
    "parallel" rods - consider this: one single rod may already
    'attract' enough magnetic field lines from the far field; 7 rods
    will not attract 7 times as much ! Anyway for backpack operation you
    don't have the choice to build a meter-long rod like Lubos' large
    antenna.<br>
    <br>
    Beware that my crossed-loop antenna was built for VLF, not LF. <br>
    <br>
    Cheers,<br>
        Wolf .<br>
    <br>
    <br>
    Am 15.08.2011 19:26, schrieb Stefan Schäfer:
    <blockquote cite="mid:4E4956DA.1060201@iup.uni-heidelberg.de"
      type="cite">
      <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
      Hello Wolf, <br>
      <br>
      Thanks to the link to your nice to read article. I just found it a
      hour
      before your mail and already read it ;-)<br>
      <br>
      Well, i also prefer the usual configuration instead of that sleeve
      antenna. Also i have to keep the focus on my actual goal: Making a
      handy antenna for amateur LF / p operation without a car! And the
      16
      rods i will get (14 cm long, 8mm diameter) will be best in a 2x7
      config. i think. Or do you rather suggest 3x5 or even 4x4?<br>
      2x7 is then about 30 cm long which is very fine for a backpack and
      should be robust enough.<br>
      I would use the same double side bonding tape, this is very useful
      to
      get a first fixed arrangement. Then putting all that in a PVC
      tube, 2mm
      thickness and add the turns above the tube. <br>
      Would you recommend litz wire or standard 0.5 mm enamelled wire?<br>
      As an E field shield i would use aluminium bonding tape, without
      making
      a shutcut turn of course.<br>
      <br>
      So the newcomers should not think that this antenna is the best
      what
      one can use for LF. Just in that special case of /p i see
      advantages.
      Otherwise a well designed loop (+ preamp or a very sensitive RX,
      if a
      samll loop is used) or E field antenna such as the PA0RDT should
      be
      preferred, as Alan already pointed out.<br>
      <br>
      Looking forward to a direct comparison of the DCF39 SNR that can
      be
      achieved and to the first amateur signal received with that
      antenna in
      /p...<br>
      <br>
      73, Stefan/DK7FC<br>
      <br>
    </blockquote>
    <br>
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