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Re: LF: Effective antenna height?

To: [email protected]
Subject: Re: LF: Effective antenna height?
From: Andy Talbot <[email protected]>
Date: Sat, 23 Sep 2017 11:50:32 +0100
Cc: rsgb_lf_group <[email protected]>
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I now see that same text is repeated on page 52 of the   LF Experimenter's Handbook, so the pages I just copied don't give any extra info .

There was no further detail to be found in either of the two earlier LF Source Books

Oh well

Andy  G4JNT

On 23 September 2017 at 11:37, Andy Talbot <[email protected]> wrote:
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

Andy  G4JNT

On 23 September 2017 at 11:18, Mike Dennison <[email protected]> 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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