From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: rsgb_lf_group@yahoogroups.co.uk, rsgb_lf_group@blacksheep.org
Date: Sat, 23 Sep 2017 15:32:01 +0100
MIME-Version: 1.0
Message-ID: <59C67061.15051.28B4EECA@mike.dennison.ntlworld.com>
In-reply-to: <CAA8k23TSNYLvwWfVdn7zWj1CXgzcify7K14GiKyQpZW5LznGTg@mail.gmail.com>
References: <59C634ED.8252.27CCAAE3@mike.dennison.ntlworld.com>, <CAA8k23TSNYLvwWfVdn7zWj1CXgzcify7K14GiKyQpZW5LznGTg@mail.gmail.com>
Content-description: Mail message body
Subject: Re: [rsgb_lf_group] Re: LF: Effective antenna height?
Content-type: text/plain; charset=US-ASCII
Content-transfer-encoding: 7BIT
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Thanks to Andy (your pages included the important reference to Watts' 
VLF Radio Engineering) and to Dave for the pages from Watts. I now 
see how useful it was for Peter Dodd to digest the original data into 
simple figures for a typical amateur station. I will add this 
reference to the next edition of LF Today (if I am asked to do one!) 
and to the LF chapter of the Radio Communication Handbook.

Mike, G3XDV
==========

> 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
> > ==========
> >
> >
> 
> 
> ---
> This email has been checked for viruses by AVG.
> http://www.avg.com
>