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[Ham-80211] Re: Amateur Radio and Emergency Communications

Al Wolfe awolfe at Route24.net
Thu Jun 23 06:08:30 UTC 2005

    FWIW, I believe FEMA, the Corps of Engineers, and others, have done
survivability studies of various radio and electronic equipment and the
bottom line as I remember it was that any equipment with an antenna (or
other wires, protuberances) longer than about four feet was vulnerable. The
faraday cage may be overkill. A piece of equipment sitting on a shelf in a
box or with no cords or wires attached should be fine.
    Walky-talky type of radios would most likely survive an EMP attack.
Portable receivers would likely survive.
    Most commercial broadcast transmitting equipment would survive as it is
typically well grounded and shielded. The majority of this equipment, at
least in the higher power levels still use tube finals (although that is
changing.) Most of the commercial broadcasting equipment survives direct
lightning hits as a matter of course.
    Most 802-11 equipment antennas are smaller than four feet. Most of the
EMP energy is in the MF and HF frequency range so the path of ingress for
EMP damage would most likely be from the power and data lines to outdoor
installations. Laptops not connected to external power sources would likely
    Passive antenna structures should survive. A spare rig on the shelf that
can be powered from batteries or a twelve volt source would be a good idea
as most vehicles should work as long as the gas holds out. Commercial AC
power will most likely not be available.

Al, K9SI

> Date: Wed, 22 Jun 2005 17:41:46 -0500
> From: Chuck Mayfield <charleslmayfield at comcast.net>
> Subject: Re: [Ham-80211] Amateur Radio and Emergency Communications
> To: "TAPR Mailing List for Ham Radio Use of 802.11"
> <ham-80211 at lists.tapr.org>
> Message-ID: < at localhost>
> Content-Type: text/plain; charset=us-ascii; format=flowed;
> x-avg-checked=avg-ok-1E9C452C
> I have been monitoring several groups that seem to be pushing digital
> communications via internet and radio for emergency communications.
> In the National Interest, our overall emergency communications plan needs
> to include safeguarding some sort of communications capability against
> EMP,
> even if it is CW and SSB and NTS or equivalent.
> 73,
> Chuck Mayfield, AA5J
> Plano, Texas

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