[MLB-WIRELESS] Lightning protection?

[Timshel Knoll]

On Fri, Feb 08, 2002 at 10:59:01AM +1100, lkhoo at csc.com.au wrote:
> After an eventful night with the weather last night (I live in Lilydale and
> got pretty much flooded!) I started thinking about what would happen if an
> antenna used for wireless was hit by lightning?  I'm not very knowledgeable
> in this area so I suppose this would apply to the average TV antenna also.
> 
> Does anyone have any protection for their gear from this sort of thing? Or
> are the chances of a strike so slim that there is no point in doing
> anything?
> 
> Thanks
> 
> Lucas Khoo

I remember seeing a lightning protector on an electric fence - it
basically consisted of a large inductor on the main electric fence line,
with an earth connection with a break of around 5 mm in it so that the
fence current would not be affected. Supposedly the lightning would
rather spark across than be inducted - protecting the electric fence
unit.

  [antenna]
     |              ________
     |             ////////\\
     |             ||||||||||
     |_____________\\\\\\\\//____[computer]
     |     
        (~5 mm spark unit)
     |
     |
  [earth]

The spark unit basically consisted of a ceramic piece with 2 bolts,
around 5 mm apart, with the fence connected to one bolt, and a 10 or
20mm (I can't remember) earth wire to the other. The inductor was
uncored, with around 20 winds of ~15cm diameter, each one 3-4cm apart.
I don't know how much the inductor would affect the signal, that may be
a deciding factor in whether to use this system. If it doesn't affect
the signal too much, it might be worth coupling this with a lightning
rod system ...

Cheers,

Timshel

-- 
   Timshel Knoll <timshel at pobox.com>  for Debian email: <timshel at debian.org>
      Debian GNU/Linux developer, see http://people.debian.org/~timshel/
                For GnuPG public key: finger timshel at debian.org

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