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From: Andy Talbot <andy.g4jnt@gmail.com>
Date: Sat, 23 Sep 2017 11:37:30 +0100
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To: rsgb_lf_group@blacksheep.org
Cc: rsgb_lf_group <rsgb_lf_group@yahoogroups.co.uk>
Subject: Re: LF: Effective antenna height?
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I have the very book in front of me.  The LF Source Book

There is a littel bit of justification for those values, but not much.
They seem to be experimental
Photo of the two pages covering LF Verticals can be found here

http://www.g4jnt.com/DropF/lfsourcebookpg210.jpg

http://www.g4jnt.com/DropF/lfsourcebookpg211.jpg

Andy  G4JNT


On 23 September 2017 at 11:18, Mike Dennison <mike.dennison@ntlworld.com>
wrote:

> Knowing the effective height of a Marconi antenna is essential in the
> calculation of radiated power /antenna efficiency at LF/MF. The
> formula for this includes figures for the capacitance to ground of
> the vertical and horizontal wires. The result being somewhere between
> 50% and 100% of the actual height.
>
> As long as I have been interested in LF - over 20 years - I have seen
> (and used) a figure of 5pF/m for the capacitance of the horizontal
> wire and 6pF/m for the vertical wire. However, I have recently been
> asked how this figure originated, and must admit that I don't
> remember. Was it amateur experimentation, or a professional source
> such as the Admiralty Handbook? The very first amateur UK LF book, a
> slim spiral bound volume by Peter Dodd, may have the answer but I
> don't have a copy. Peter's bigger follow-up book, The Low Frequency
> Experiemnter's Handbook, published in 2000, already takes these
> figures as understood.
>
> Can anyone help, please?
>
> Mike, G3XDV
> ==========
>
>

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<div dir=3D"ltr">I have the very book in front of me.=C2=A0 The LF Source B=
ook<div><br></div><div>There is a littel bit of justification for those val=
ues, but not much. =C2=A0 They seem to be experimental</div><div>Photo of t=
he two pages covering LF Verticals can be found here</div><div><br></div><d=
iv><a href=3D"http://www.g4jnt.com/DropF/lfsourcebookpg210.jpg">http://www.=
g4jnt.com/DropF/lfsourcebookpg210.jpg</a><br></div><div><br></div><div><a h=
ref=3D"http://www.g4jnt.com/DropF/lfsourcebookpg211.jpg">http://www.g4jnt.c=
om/DropF/lfsourcebookpg211.jpg</a><br></div><div><br></div><div>Andy =C2=A0=
G4JNT</div><div><br></div><div><br></div></div><div class=3D"gmail_extra"><=
br><div class=3D"gmail_quote">On 23 September 2017 at 11:18, Mike Dennison =
<span dir=3D"ltr">&lt;<a href=3D"mailto:mike.dennison@ntlworld.com" target=
=3D"_blank">mike.dennison@ntlworld.com</a>&gt;</span> wrote:<br><blockquote=
 class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc soli=
d;padding-left:1ex">Knowing the effective height of a Marconi antenna is es=
sential in the<br>
calculation of radiated power /antenna efficiency at LF/MF. The<br>
formula for this includes figures for the capacitance to ground of<br>
the vertical and horizontal wires. The result being somewhere between<br>
50% and 100% of the actual height.<br>
<br>
As long as I have been interested in LF - over 20 years - I have seen<br>
(and used) a figure of 5pF/m for the capacitance of the horizontal<br>
wire and 6pF/m for the vertical wire. However, I have recently been<br>
asked how this figure originated, and must admit that I don&#39;t<br>
remember. Was it amateur experimentation, or a professional source<br>
such as the Admiralty Handbook? The very first amateur UK LF book, a<br>
slim spiral bound volume by Peter Dodd, may have the answer but I<br>
don&#39;t have a copy. Peter&#39;s bigger follow-up book, The Low Frequency=
<br>
Experiemnter&#39;s Handbook, published in 2000, already takes these<br>
figures as understood.<br>
<br>
Can anyone help, please?<br>
<br>
Mike, G3XDV<br>
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D<br>
<br>
</blockquote></div><br></div>

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