[time-nuts] Best location for a GPS antenna...?

Chris Albertson albertson.chris at gmail.com
Thu Apr 12 21:07:56 EDT 2012


On Thu, Apr 12, 2012 at 2:21 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> Do you have a reference for 100' distant strikes routinely destroying
> receivers?
>
> Bob
>
>

The ARRL's "QST" magazine Aug -> Nov 1986 is very good and many people here
would have access to it.
They talk about EMP from both atomic weapons and lightening.  The EMP from
atomic explosions is as you'd yes worse.  If can destroy most electronics
up to 450 miles away in the worse cast (an explosion in the ionosphere.)

Lightening has vary wide band energy in its EMP and the farther you are
away from it the lower the frequency.  So a very close strike might have
much energy at UHF a strike 50 feet away might be only up to HF range.   So
it couples to different length conductors depending on the distance.    My
reference to 100 feet means you'd need some length on the feed line and
data cables.

There is a good publication from some one at a university in Florida having
to do with electronics on boats. I can't find it now.


-----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Chris Albertson
> Sent: Thursday, April 12, 2012 3:25 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>
> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
> <randy_hunt960 at yahoo.com>wrote:
>
> > On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
> >
> >> What about mounting the antenna on the side of the metal pole, with the
> >> top of the pole extending a foot or more above the antenna?
> >
> >
> Typically when a receiver or other radio is destroyed it was NOT because of
> a direct strike.  A strike within maybe 100 feet is enough.  There is a
> _huge_ EMP field around the strike.  The field will induce large currents
> in any nearby conductors.   Even if the strike is to bare Earth many feet
> from the antenna the potential of the earth is raised by say 1,000 volts so
> now anything connected between ground the power has 1KV across it.
>
>
>
>
>
> Chris Albertson
> Redondo Beach, California
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-- 

Chris Albertson
Redondo Beach, California



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