[BC] Amatuer radio spectrum

[Ronald J. Dot'o Sr.]

There are a lot of misconceptions about EMP and a lot of ways to 
survive it.

Most of the pulse is in the lower frequency spectrum and is gathered 
by long runs of wire (power, phone, cable TV, long conduit runs etc.) 
that act as an antenna and bring the pulse indoors and fries 
everything.

Being right underneath the burst is the worst thing but being on the 
fringe area of the burst many detached items will probable survive. 
There is very little power in the VHF and above spectrum produced.

Detached things like cars, garbage cans, wall lockers etc. gather 
relatively little EMP.

A small handheld HT would hardly gather any EMP at all as it makes for 
a very small antenna.

Its effect on cars is questionable as they are relatively small and 
may or may not be effected due to the robustness (or lack of it) of 
the ignition system and the possible shielding provided by the car 
body and hood.  Keep in mind that EMP is a lot like lightning in some 
respects, only a whole lot faster.

When lightning strikes an airliner nothing much happens as the current 
has nowhere to go and the charge dissipates.  The same thing would 
happen with a car unless the car gathered enough charge to arc over to 
the ground underneath it and even then it's questionable if the 
ignition would be harmed.

Modern emergency generators due to their relatively small size 
probably wouldn't be effected at all.

A lot of urban myth about EMP in the same class as putting tin foil in 
your hubcaps will defeat speed radar has been propagated and muddied 
the waters.

FEMA put on a school for broadcast engineers from EBS stations and 
Techs who maintained EOC's back in the early '80's and taught us how 
to analyze requirements for, and how to harden stations for EMP, which 
was also excellent lightning protection.

Anything used as a Faraday cage, grounded or not, such as a metal 
garbage can or wall locker is a very good idea.

Theory only goes so far.  To really find out the effects of EMP you 
would need to have one and see what really happens.

Remember that with the size of the "antenna"  SIZE MATTERS!

For more info see my article in Radio Guide.  I think it was in March 
and April issues in '04 but I could be wrong on that as it's been a 
while.

Ron D

----- Original Message ----- 
From: <RichardBJohnson at comcast.net>

> In the event of an EMP attack, even your vacuum-tube
> rig will fail because all the capacitors will be shorted.
>
> It's true that you might be able to store one
> in a metal trash-can and it might work if you
> can find someone with the same foresight
> with which to communicate. Make it short, you
> batteries won't be recharged for a long, long time!
>
> If you happen to have an old generator like those
> used in WWII, the ones with the Jeep engines, you
> might be able to get it running. Modern ones with
> SS controllers won't be SS anymore.
>
> Cheers,
> Richard B. Johnson
> Book: http://www.AbominableFirebug.com/
>
> ----- Original Message -----
> From: "Glen Kippel" <glen.kippel at gmail.com>
>
> But, I might
> point out that, in the event of an EMP attack, the hams that had the
> foresight to put a rig or two, or three, in a metal trash can that 
> has a
> metal strap connecting the aforementioned trash can to a ground 
> stake, will
> be the only ones who will be able to communicate.  Obsolete 
> technology or
> not.  Think about that.
>