Message-ID: <4C4EFB49.3050409@iup.uni-heidelberg.de>
Date: Tue, 27 Jul 2010 17:29:13 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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References: <uBz9GbEK3dRMFw2w@mcrosolv.demon.co.uk> <C3D24A10-4CE6-46F8-B312-85311A1433B0@numeo.fr> <AANLkTim8Wn24AuBvmYO94VxzsGNKwW62PVNcrj2fUyGg@mail.gmail.com> <FFEBAEAD-5B4E-4F05-B8F4-6EBCC0ACE0F5@numeo.fr>
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Subject: Re: LF: David Gibson on Earth antennas and propagation below 9 kHz
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YES! Very fine John! What do you plan? Which QRG and which wire length? 
My hint is to use a mountain if you have one beside your QTH.
Whish fun and good luck and await your results/report!

73, Stefan

Am 27.07.2010 16:53, schrieb John Rabson:
> Andy,
>
> I hope to be doing some aerial  experiments (yes - above ground not 
> below) in the next few weeks and will see if I can put something up 
> and do some measurements.
>
> 73
> John F5VLF
>
> On 26 Jul 2010, at 16:09CEST, Andy Talbot wrote:
>
>> I was thinking about this, and thoughts turned to a rather simpler 
>> antenna;  the folded dipole and how it would behave when electrically 
>> short.
>> A simple non-folded  electrically short dipole (negelecting all 
>> losses)  has Rin proportional to 1/L^2 and a highly capacitive 
>> reactive term
>> A folded half-wave dipole fed conventionally has Rin about 4* that of 
>> a normal dipole due to current sharing in the legs -.
>> Now the conumdrum - what does an electrically short folded dipole 
>> look like?     It has got to be inductive, since we're feeding into a 
>> squashed shorted turn, and presumably the current distribution looks 
>> short dipole-ish.
>> So is it a loop, is it a dipole, is it both, how can it be both, if 
>> it is what's its radiation pattern ?
>> Similar to the ground loop/dipole question ?
>> And is there a length where the inductance of the loop bit resonates 
>> with the capacitance that 'ought' to be there due to its also being a 
>> short dipole.
>> ?????????????????????????????????????
>> Andy
>> www.g4jnt.com <http://www.g4jnt.com/>
>> (not really an antenna sort of person)
>

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YES! Very fine John! What do you plan? Which QRG and which wire length?
My hint is to use a mountain if you have one beside your QTH.<br>
Whish fun and good luck and await your results/report!<br>
<br>
73, Stefan<br>
<br>
Am 27.07.2010 16:53, schrieb John Rabson:
<blockquote cite="mid:FFEBAEAD-5B4E-4F05-B8F4-6EBCC0ACE0F5@numeo.fr"   type="cite">Andy,
  <div><br>
  </div>
  <div>I hope to be doing some aerial &nbsp;experiments (yes - above ground
not below) in the next few weeks and will see if I can put something up
and do some measurements.</div>
  <div><br>
  </div>
  <div>73</div>
  <div>John F5VLF</div>
  <div><br>
  <div>
  <div>On 26 Jul 2010, at 16:09CEST, Andy Talbot wrote:</div>
  <br class="Apple-interchange-newline">
  <blockquote type="cite">
    <div>I was thinking about this, and thoughts turned to a rather
simpler antenna;&nbsp; the folded dipole and how it would behave when
electrically short.</div>
    <div>&nbsp;</div>
    <div>A&nbsp;simple non-folded &nbsp;electrically short dipole (negelecting
all losses)&nbsp; has Rin proportional to 1/L^2 and a highly capacitive
reactive term</div>
    <div>&nbsp;</div>
    <div>
    <div>A folded half-wave dipole fed conventionally has Rin about 4*
that of a normal dipole due to current sharing in the legs -.</div>
    <div>&nbsp;</div>
    </div>
    <div>Now the conumdrum - what does an electrically short folded
dipole look like?&nbsp;&nbsp;&nbsp;&nbsp; It has got to be inductive, since we're feeding
into a squashed shorted turn, and presumably the current
distribution&nbsp;looks short dipole-ish.</div>
    <div>&nbsp;</div>
    <div>So is it a loop, is it a dipole, is it both, how can it be
both, if it is what's its radiation pattern ?</div>
    <div>Similar to the ground loop/dipole question ?</div>
    <div>&nbsp;</div>
    <div>And is there a length where the inductance of the loop bit
resonates with the capacitance that 'ought' to be there due to its also
being&nbsp;a short dipole.</div>
    <div>&nbsp;</div>
    <div>?????????????????????????????????????</div>
    <div>&nbsp;</div>
    <div>Andy<br>
    <a moz-do-not-send="true" href="http://www.g4jnt.com/">www.g4jnt.com</a>
    </div>
    <div>(not really an antenna sort of person)<br>
    </div>
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