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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