[time-nuts] GPS antenna selection — lightning
attila at kinali.ch
Fri Aug 5 16:51:06 EDT 2016
On Fri, 5 Aug 2016 10:37:28 -0400
Eric Scace <eric at scace.org> wrote:
> A GPS antenna and its coax line that is installed next to a window is no
> different from the same antenna/coax installed one meter outside the window…
> or 10 meters away outside the window. All three installations are
> effectively “outdoors” from an electromagnetic viewpoint, and all three need
> effective surge protection from lightning-, cloud-, and precipitation-
> induced voltage surges.
Please please please do NOT spread dangerous information like this!
While it is true, that an indoor antenna is suceptible to surges like
an outdoor antenna, it is not true that an outdoor antenna is equivalent
to an indoor antenna when it comes to lightning protection.
Because an outdoor antenna can be _directly_ hit by a lightning.
To protect the house and its inhabitants from the lightning strike,
an external antenna needs to be either lower than any lightning rod
and within its 45m ball or needs its own conductor and grounding
to discharge any lightning energy and thus preventing it from following
the antenna cable into the house.
Please be aware that the grounding of the antenna is not to protect
the equipment from surges, but to prevent conduction of the lightning
into the house that could cause electrocution and fires.
Any simple idea will be worded in the most complicated way.
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