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How To Communicate In An Emp Zone?

  1. Jul 5, 2006 #1
    Hey fellas.

    Help me out here,
    lets imagine that a certain area (lets call Zone) suffers an Electro-Magnetic Pulse by a "pinch" machine. So, the wires, and electronic communications are gone...my question is how can a person inside the "Zone" communicate with the exterior? Lets imagine we could dispose of any material that can be imaginable.
    Plus, the kind of communication im talking about is long-distance...smoke signals and lights are out!! LOL

    A collegue of mine said the telegraphic system (via morse code) could work! Can this be?

    Thanks for the time!
  2. jcsd
  3. Jul 5, 2006 #2

    Claude Bile

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    Science Advisor

    Only microelectronic systems are vulnerable to an EMP - Macroelectronic systems should still survive, mainly because the tolerance to spike currents etc is so much higher than for microelectronics.

    Therefore, only communications systems that depend on microelectronics would be disabled. For example, telephone systems would be out, both mobile and landlines, while radio should still work. Telegraphs of course, would also work.

  4. Jul 5, 2006 #3
    An EMP is transient... it's a "pulse"
    Only susceptable devices during the event and within the "kill" radius are affected.
    Sure, a close or powerful EMP can fry the semiconductor electronics of your computer, walkie-talkie, ham radio, etc... but after the pulse one could easily scrape together enough components for some sort of electronic communication.
    But the important point is this: having a handheld ham radio in a EMP-proof container would allow you to use that radio after the "pulse" The EMP pulse does not "contaminate" the environment in some lingering sense. It destroys quickly and leaves quickly(both at about the speed of light)
    So, protected communication devices can operate freely after an EMP event.
  5. Jul 6, 2006 #4
    hum...i see...Thank you Claude Bile and pallidin...about that EMP-proof container...what would resist such a pulse?
  6. Jul 6, 2006 #5
    A tin box.
  7. Jul 8, 2006 #6

    I was just about to say the same thing. Or if you want to get stylish all over it... a mumetal box. Moooooometal costs 'phat' green though, really 'phat' green.

    Outside of the scientific world, audiophiles are the only people I know of who make use of mumetal type alloys. I believe they're usually very high in Cobalt, which is why they cost quite a lot.

    People who deal with otherwise complex or weird magnetic field problems.
    Last edited: Jul 8, 2006
  8. Jul 11, 2006 #7
    suuuuure...a tin box uh...I can really imagine the survivors of an atomic wave followed by it's EMP calling in from their cellphones stored inside their cookie tin boxes saying "Hey Bob, guess what! BOMBS AWAY!!"
    FOR REAL!!! EMP can destroy all cable communications of an entire country and it cant penetrate a tin box... I'm no rocket scientist but i'm gonna doubt that one!

    thankx anyway!
  9. Jul 11, 2006 #8
    Oh ye of little faith:


    One survival system for such sensitive equipment is the Faraday box.

    A Faraday box is simply a metal box designed to divert and soak up the EMP. If the object placed in the box is insulated from the inside surface of the box, it will not be effected by the EMP travelling around the outside metal surface of the box. The Faraday box simple and cheap and often provides more protection to electrical components than "hardening" through circuit designs which can't be (or haven't been) adequately tested.

    Many containers are suitable for make-shift Faraday boxes: cake boxes, ammunition containers, metal filing cabinets, etc., etc., can all be used. Despite what you may have read or heard, these boxes do NOT have to be airtight due to the long wave length of EMP; boxes can be made of wire screen or other porous metal.

    The only two requirements for protection with a Faraday box are: (1) the equipment inside the box does NOT touch the metal container (plastic, wadded paper, or cardboard can all be used to insulate it from the metal) and (2) the metal shield is continuous without any gaps between pieces or extra-large holes in it...
    Last edited: Jul 11, 2006
  10. Jul 14, 2006 #9
    I meant to say.... Nickel

    And yes, a tin box will work.

    The EMP from something like a nuclear bomb will occur as a very fast transient spike, like lightning. Which means anything conductive in it's way will probably have quite a high inductive reactance to it as it tries to pass through.

    You can easily put the same amount of energy as you'd find in one lightning strike through the grid over time, the problem comes when you try to put that much instantaneous power through it. In general, the more violent a thing becomes, the harder it's targets try to resist it - as per hisenberg's and le chatelier's thoughts on life.
    Last edited: Jul 14, 2006
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