Re: NEC-LIST: Coil-loading.

Thanks Roland,

The purpose of a loading coil partway up an
electrically-short whip is to pull up the average current in
the lower section, which raises the radiation resistance and
possibly the efficiency. The telegraph transmission line
coils suggested by Heaviside were to raise the L/C of the
line to match its R/G (resistance per unit
length/conductance per unit length) to produce a real
characteristic inpedance and a phase shift proportional to
frequency, which reduces the pulse smearing that otherwise
occurred on long lines. My recollection of the prototype
story is that the head of the British Post Office said
something like "engineers don't do math" and ignored
Heaviside. It was a professor at one of thos small New York
colleges, like Hunter College or Cooper Union, who built the
first prototype and sold the idea to AT&T, so the Americans
did the first successful trans-Atlantic cable.

Regards,
Doug Miron

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