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EMP basic cages....

Discussion in 'General Survival and Preparedness' started by dragonfly, Aug 4, 2010.

  1. dragonfly

    dragonfly Monkey+++

    Here I used 2 x 2's and some perforated board for a shelf, covered in aluminum window screen. Hardware is brass: hinges, screws, etc. The staples only serve to close the cage. The main cage is ready without the ground wire, or a closure/lock device. The second cage is really basic! No hardware, just screen over the 2 x 2's and a base of perf board. The entire thing is stapled closed, ( I left the staples sticking out, for ease of removal later on....) Note: all edges save the actual door opening/s, are overlapped, and folded in a variety of ways to ensure electrical continuity.
    Doubling of the screen covering is essentially doubling the safety of the cage system....A much larger cage can be made with mutiple shelves for a number of items to be protected, and some people use 2 x 4's and screen. Drawback: screen is easily damaged and punctured! You can re-cover the window screen areas with hardware cloth to ensure even more protection.
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  2. fortunateson

    fortunateson I hate Illinois Nazis!

    Cool. Now it's time to test it :0
    Dunno, maybe aim a magnetron at it?

    Where did you get your plans Dragonfly?
    I ask because I've heard it said that EMP covers such a broad band that you can't accurately judge the screen size.
  3. dragonfly

    dragonfly Monkey+++

    1) I was ADM "certified" in Hanau Germany GMBH. ( 1970) ("sadm's to the newer guys!)
    2) AEC security certification
    3) NRC security certification
    4) Employed at the Palo Verde Nuclear Generating Station here outside of Phoenix.
    5) Hours of research
    Most sites whether military or independent studies, have stated that due and owing to the multitude of the wavelengths encountered from an EMP scenario, the best that anyone has come up with thus far, was the less than 1mm in any dimension size, would and have safely caught and deterred nearly all wavelengths. Light of any and all types are excluded of course!
    I personally "tested" several items and ways to stop different radio signals...from cellular phone, to radio waves from: am-fm, vhf-uhf, cb ( 27mhz) and from 6 Meter to 10 Meter ham. We used up to 250 watts ( amplified via linear devices). We were able to easily penetrate the following: 20 & 32 gallon galvanized trash cans ( new with tight fitting lids..) Aluminum foil wrappings: 2 complete wrappings actually work to ONLY stop some signals, in and out, but NOT of any sunstantial power ( amplified) signals). Ammo cans, .50, 7.62, and 5.56 types...all failed. The very best we tested was a 100 ft. roll of chicken wire! ( go figure that one out!)
    Left rolled up, and with the ends OPEN, it stopped everything we threw at it!
    But with only a space of 36 inches long and 4 inches in diameter, it was of little help when it came to protection of larger items!
    Metal enclosures, even though they are completely sealed, with NO openings seen, did little at all. Cans, barrels, ammo cans, were all weak and useless.
    We did a test using just aluminum screen over a 1 x 2 frame, with little metal except the staples to hold the wire and a few screws to hold the frame in place, stopped all we had to test with. I was surprised to say the least. Now, IF the "box" or whatever you build with the screen, is NOT grounded, it has little effect on most signals of a variety of wavelengths....The ground is the most important part. It dissipates the waves as they hit the mesh, and discharge them away from anything in the container. The electrical items inside must NOT touch any part of the mesh, and must be insulated from all parts of the cage, with the exception of the wood, or whatever you choose to use for a shelf. I use 6 gauge solid copper wire to ground and have the cages hooked up to 2 grounds: 1) a cold water pipe 2) the telephone pole ground.
    No connections allowed in or out of the cage is what makes the cage work. No cords, cables, coax, nothing is allowed in or out of the enclosure. Even the door must seal as tightly as possible, and I even leave extra screen to fold over again to the frame, to make sure there are no small openings.
    Many people considered using those conex containers...That is a bad idea. Large masses of metals have a bad and nasty habit of collecting an assortment of wavelengths and concentrating them. In fact, any large mass of metal does the same thing, including steel I beams. Some think that a mobile home is ideal due to the aluminum covering ( newer models as opposed to the old ones with galvanized sheet metal). Again, you'd have a heck of a time trying to seal the entire thing up sufficiently, with either aluminum foil, or screen. Remember that less than 1mm? That's pretty small! Brass screen has been tested, and shown to be fantastic, but it's very heavy and really expensive, but one of the best outside of using GOLD or SILVER mesh! The finer the mesh the better....the better the ground the better, the more conductive mesh/screen the better...
    There are many different substitutes, but I chose what worked for me, and that which I could easily afford and build with.
    Your individual results may vary!
    Want to do a small test for kicks?
    Take 2 cellular phones, put one in the TEST medium of your choice and call it from the other!...See if the test medium can stop the most basic cellular phone signals! Then go further! Try radios receiving on local am/fm channels!
    See what it takes to stop those signals!
    It gets fun after the first tests!
    Good Luck!
    kellory and 3M-TA3 like this.
  4. fortunateson

    fortunateson I hate Illinois Nazis!

    Well that sure answers it!

    Thanks for the research.
  5. dragonfly

    dragonfly Monkey+++

  6. bnmb

    bnmb On Hiatus Banned

    Thanks dragonfly...very nice post!
  7. padkychas

    padkychas Monkey+++

    I work on MRIs and each is in a Faraday cage, there are aluminum, galvanized steel and copper rooms. the best is the copper but it is price prohibitive now days. The windows (made of 3 layers of screen wire at 90 and 45 degree angles) and doors in the MRI rooms are the worst spots for db. signal level suppression.
    You can get filters to pass AC or DC to bring power into the cage but they do fail and are pricey.
    My thoughts are a dedicated EMP box should not be to hard to make out of a 55 gallon drum with a locking ring removable top. if the paint is removed from the top rim of the drum and the inside of the lip of the top with a compressed wire mesh seal (the 1" braided wire ground strap will work very well when it is compressed with the locking ring) and a very good dedicated ground rod will make a good EMP resistant storage spot for your electronic stuff. remember to line the box-drum with and insulator- plastic or cardboard to keep things from touching the inside of the faraday cage.
    The ground is very important that it is a new dedicated ground rod and heavy cable that is bonded to the drum and top. The ground in your house will be over whelmed in a EMP event, remember the long wire threw out your house is an antenna and the ground in your house is common to the neutral on the power pole, this will have a big spike on it, the short cable and dedicated ground rod will have much lower EMP energy to "ground" (dump) into the earth, the Faraday cage will be more able to protect the contents.
  8. Sparky

    Sparky Monkey+

    Does anyone have any thoughts on the suitability of silver-containing cloth for use on small items? I've worked with silver-coated polyester (anywhere from 1-15% silver) that's used as bandaging for severe burns and always wondered about possible EMP applications. The stuff comes in long rolls up to 4 foot wide and is very easy to drape. Pricey at about $50/square yard though. Thanks.
  9. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Never heard of it, but that means pretty much nothing. Do you have a link?
  10. dragonfly

    dragonfly Monkey+++

    I have seen silver threads sewn into cloth, and for a short time they were being sold on the internet, as bed covers....Like sheets or covering over 4 poster type beds, some were much like mosquito netting!
    I suppose it was primarily for those with "pacemakers" or the like.
    Any tightly woven metallic thread would be a great protection against EMP.
    Not sure how expensive it would be, But nothing's cheap anymore anyways!
    Now, I wonder..."IF" a layer or two of heavy duty grade aluminum foil, sandwiched between aluminum ( or whatever) screening, would afford much more protection with a solid surface.....
    That would have to be tested.
    I like it already!
  11. GeoMonkey

    GeoMonkey Monkey++

    Thanks for doing all the research and letting us in on your project.
    Hope we never have to use it, eh?
  12. Sparky

    Sparky Monkey+

    The silver fabric was a test roll that the lab I work in received to do some evaluations and it ended-up in the discard pile afterwards. Pretty neat stuff. It's made by a proprietary process that imbeds an even coat of silver onto polyester threads that are then woven into cloth. The version I have with 15% silver is too pricey to my mind if you have to buy it but since it didn't cost me anything I've been trying to figure out how to make the best use of it. Doesn't seem to want to pass a radio frequency signal but I'm not sure what it's wavelength cutoffs are.

  13. padkychas

    padkychas Monkey+++

    the tests that you talk about, were the enclosures that did not do well, were they grounded?
    the MRI rooms I work on are just sheet copper or steel boxes with sealed doors and screened (x3) windows that have an dedicated and isolated ground. these get a 60db reduction on signal normality in use.
  14. joncro55

    joncro55 Monkey+

    Any material like this that contains any trace of pure silver will be extremely pricey.

    I have looked around the internet and the best price that I can find thus far is with this company in New Jersey.

    Belleville Wire Cloth - wire cloth, wire cloth, wire mesh, woven wire, stainless steel wire mesh, mesh wire, woven wire mesh, wire mesh basket, wire mesh screen, woven wire cloth, stainless steel wire cloth, wire cloth screen, wire cloth strainer, in

    I called for pricing and I believe they have something comparable in stock although its tough to explain over the phone.
  15. dragonfly

    dragonfly Monkey+++

    None of the original tests were done with any grounds connected.
    I was concerned about the penetration of different wavelengths only at the time....Not sure if that would make much difference since most were in the radio signal spectrum. Someone once came up with a "wet blanket" idea....I don't know how it worked out, but it sounded reasonable! Trouble is having a wet covering all the time! Maybe a gel of sorts? Perhaps made from a collodial silver solution?
  16. Ganado

    Ganado Monkey+++

    NIce Project bump
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