Message-ID: <5A7377F7.4050802@posteo.de>
Date: Thu, 01 Feb 2018 21:26:31 +0100
From: DK7FC <selberdenken@posteo.de>
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References: <579355A36AEE9D4FA555C45D556003AB9AB485D3@servigilant.vigilant.local>
In-Reply-To: <579355A36AEE9D4FA555C45D556003AB9AB485D3@servigilant.vigilant.local>
Subject: Re: LF: VLF Small magnetic antenna for Tx
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Hi Luis,

You seem to generate much activity on all bands in your Spanish region 
:-) That is fine!

Am 01.02.2018 19:58, schrieb VIGILANT Luis Fernández:
>
> As this is the "near field" it is supposed to work only at magnetic 
> field due to the small size of the antenna ? So only magnetic field for
>
> underground signals at this distances ?
>
The E field also works in the near field of course but through the 
ground you will have no chance with an underground E field TX antenna 
:-) Just try it on LF at home :-)

> Can we expect to receive the signal with an electric probe antenna in 
> the near field or the only chance is to be further away ?
>
In the moment i can receive my 970 Hz signal radiated from the E field 
antenna and received by the H field antenna. But it is not optimal. The 
signal strength will be higher when using the same type of antenna as 
long as you are in a range of < 0.7 * far field distance.

> Which would be the radiated power of such antenna ?
>
There are formulas on Rik's websites for 136 kHz, 
http://www.strobbe.eu/on7yd/136ant/#Loops

73, Stefan

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Hi Luis, <br>
<br>
You seem to generate much activity on all bands in your Spanish region
:-) That is fine!<br>
<br>
Am 01.02.2018 19:58, schrieb VIGILANT Luis Fern&aacute;ndez:
<blockquote
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  <p class="MsoNormal"><span lang="EN-US">As this is the &#8220;near field&#8221;
it is supposed to work only at magnetic field due to the small size of
the antenna ? So only magnetic field for<o:p></o:p></span></p>
  <p class="MsoNormal"><span lang="EN-US">underground signals at this
distances ?</span></p>
  </div>
</blockquote>
The E field also works in the near field of course but through the
ground you will have no chance with an underground E field TX antenna
:-) Just try it on LF at home :-)<br>
<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003AB9AB485D3@servigilant.vigilant.local"
 type="cite">
  <div class="WordSection1">
  <p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
  <p class="MsoNormal"><span lang="EN-US">Can we expect to receive the
signal with an electric probe antenna in the near field or the only
chance is to be further away ?</span></p>
  </div>
</blockquote>
In the moment i can receive my 970 Hz signal radiated from the E field
antenna and received by the H field antenna. But it is not optimal. The
signal strength will be higher when using the same type of antenna as
long as you are in a range of&nbsp; &lt; 0.7 * far field distance.<br>
<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003AB9AB485D3@servigilant.vigilant.local"
 type="cite">
  <div class="WordSection1">
  <p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
  <p class="MsoNormal"><span lang="EN-US"><o:p>&nbsp;</o:p></span></p>
  <p class="MsoNormal"><span lang="EN-US">Which would be the radiated
power of such antenna ? </span></p>
  </div>
</blockquote>
There are formulas on Rik's websites for 136 kHz,
<a class="moz-txt-link-freetext" href="http://www.strobbe.eu/on7yd/136ant/#Loops">http://www.strobbe.eu/on7yd/136ant/#Loops</a><br>
<br>
73, Stefan<br>
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