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[Ham-80211] Amateur Radio and Emergency Communications

Chuck Mayfield charleslmayfield at comcast.net
Wed Jun 22 23:26:23 UTC 2005


At 06:12 PM 6/22/2005, you wrote:

>On Wed, Jun 22, 2005 at 05:41:46PM -0500, Chuck Mayfield wrote:
> > I have been monitoring several groups that seem to be pushing digital
> > communications via internet and radio for emergency communications.
> >
> > All discussions that I have seen neglect the possibility of 
> electromagnetic
> > pulse (EMP) from a nuclear device EMP  at an altitude sufficient to 
> blanket
> > the North American continent.  After such an event, all solid state
> > electronic devices would probably be completely useless, since th EMP 
> would
> > destroy a significant percentage of the semiconducter junctions 
> included in
> > their design.  Only ancient tube type equipment and maybe equipment
> > designed with radiation hardened semiconductor devices would survive.  A
> > majority of equipment designed / developed for DOD end-users has been
> > radiation hardened since about 1985.  Other than that, almost all
> > commercial electronics is subject to destruction by EMP.  Amateur 
> operators
> > that plan to supply emergency communications after such an event must
> > either have stockpiled and kept operational tube type equipment and or
> > protected selected semiconductor base equipment by housing it in a Faraday
> > shield for protection against EMP.
> >
> > How much of what we are discussing meets these criteria?
> >
> >
> > Think about it people!  In my considered opinion, the most likely 
> terrorist
> > threat we face that could cause such a scenario is not unlikely.  All the
> > terrorists (or any other enemy for that matter) needs is a nuclear device
> > and a launch vehicle capable of sending a device about 100 km over
> > mid-North America and detonating it.  The launch site could be anywhere
> > outside (or possibly inside) the territorial boundaries of North American
> > countries.
>
>Chuck,
>
>It seems unlikely that a terrorist organization could make such an
>attack twice or more, since rockets and nuclear bombs are expensive.
>802.11 equipment is inexpensive, and computers keep getting more and
>more cheap.  Suppose radio operators make it part of their plan &
>budget to store two (or more) instances of all vulnerable equipment
>(in Faraday cages?) for rapid re-deployment?
>
>Twice I have built wireless routers inside of ammo cans.  I figure these
>would be Faraday cages, if it wasn't for the antenna & ethernet ports.
>Do you think lightning arrestors on ethernet & antenna jacks ports be
>effective against EMP?
>
>Dave

Hi Dave,
A router inside a metal ammo can would be most likely protected from EMP 
provided it was not connected to exteral systems that provided "antennae" 
longer than about 30 inches, based on what I have read.   I suggest that 
amateur radio operators store ALL their spare equipment in Faraday Cages 
(look it up on the internet).  I don't expect you to have anything to hook 
your 802 equipment to in the event of an EMP attack.   And, yes it in 
certainly conceivable that a state sponsored terrorist organization could 
accomplish such an attack.

Chuck,
AA5J
Plano, Texas



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