[TowerTalk] Lightning... and pointed rods!

[Jim Sutton]

Reference the static caused by auto antenna in AM car radio.   My
recollection is that the ball on top of an auto antenna increases the
voltage required for the electrons to stream off and create static. The
larger the surface the more voltage that is required for electron loss. This
is why wires are cut at an angle to provide a sharp point for the electrons
to stream off when considering means of reducing lightning strikes.

73/Jim/AC4CZ

David Jordan wrote:

> Mike,
>
> When AM auto radio first came out the receive antennas were first
> mounted underneath the frame of the vehicle...later they were moved to
> the top of the vehicle. There was a static build-up of a few hundred
> volts on the receiving whip when the vehicle was driven over 25mph.
> This static build up caused significant noise on the AM receiver.  The
> fix was to install a small sphere at the top of the whip. The sphere
> effectively dissipated the static build-up reducing the popping noise in
> the ca'sr radio. Some folks mistakenly thought the advance was for eye
> safety...
>
> Many years ago, I think it was SWAN, a beam went into production with
> loops of wire at the ends of the elements. Not sure if the loops were
> for additional capacitance (for shortened elements) or to reduce static
> noise or both.
>
> Also have seen commercial beams  with spheres mounted at the ends of the
> elements.  Perhaps for the same reasons described above.
>
> On 160m it's really easy to hear the snow storms coming out of the
> midwest.  Perhaps I'll borrow a few of my wife's stainless steel mixing
> bowls, put them together to form a sphere and mount one on each end of
> my dipole to see if the snow static is reduced ;-)
>
> HAVE FUN,
> dave
> WA3GIN
>
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