EMP protection

[rparker762]

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Just a quick question. If I were to place a radio in a sealed metal box, padded on all sides and in the original cardboard packaging, will it be protected in the case of an EMP if it is not grounded? I was thinking of having a pre programmed radio in a backpack kept in the cargo compartment of the wife's SUV.

[cockpitbob]

Yes, it will be fine.  A Faraday shield doesn't need to be grounded.  It just needs to be conductive and fully encompass the radio.  From what I read, you don't need to put it in a Faraday cage so long as there's no long wires connected to it.  The wavelengths in an EMP from a nuclear bomb are fairly long, so an antenna of significant length is required to collect that energy.  An HT without the antenna probably doesn't need to be in a metal box.  On the other hand, there's talk of existence of  purpose built EMP weapons that are more effective at frying electronics, so to be totally prepared you do want things in a box.  Note that the box's lid should make electrical contact along most of its edge.  It doesn't need to be 100% tight, but sections that don't make contact form a slot antenna.

[RichardSinFWTX]

I'm currently working on a YouTube video on making a Faraday can out of those popcorn tins we all seem to collect around the holidays.  I've got a small one big enough for an HT and maybe a couple small GPS units; but you can also use the really big cans and for laptops and tablets.

The same process will work for things like ammo cans or any other metal container.

I'll see if I can get it finished and posted.  Stay tuned!

[gil]

Like Bob said..

I used a cookie tin can and soldered a short wire from the lid to the can, just to make sure.. I put my radios in a pouch so they don't touch the metal.

Good for lightning protection as well.

Gil.

[RadioRay]

Forget the popcorn: I go STRAIGHT for the Danish Butter Cookie tins! 


de RadioRay ..._   ._

[RichardSinFWTX]

Yup, those will work too.  Use whatcha got!

[rparker762]

Thanks for the replies. I was thinking just wrapping the fsctory box a few times with tin foil.

[Jim Boswell]

Years ago I ask this question to a instructor at Los Alamos National Lab. This guy was a ham and taught a bonding and grounding class at LANL. We are talking about a hard-core PHD, he wrote the standards for the lab. He said to short all the inputs and outputs on the radio, wrap it in an ESDS bag and enclose it in a grounded metal container. After EMP SHTF, open the container, un-plug the shorting plugs from the unit and get on the air. Good question what you will use for power. Any and every solid state junction device will be KAPUT. Maybe an old WWII generator would still work. Most small gas motors use solid state ignition. Solar systems and regulators will be inop unless they were protected and so enclosed.

An EMP event would push mankind right back into the 1870. Talk about the ultimate bug-out conditions. Without power or hope to regain power, in just hours cities would be smoking wastlands with total mob rule. In about 3 to 5 days everyone would start to leave the cities in search of food and water. In the winter the effects of this would be much worst as people try to burn stuff and keep warm. In the US the one year survival rate would be about 10%, my best guess.

[km4mcm]

So out of curiosity, could shipping container work if it was grounded as described?

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[cockpitbob]

A shipping container would work great IF the door makes electrical contact all the way around.  Unfortunately they don't because of the rubber gasket.  A Faraday cage needs to be a complete conductive enclosure.  Any slots will force the eddy currents flowing in the metal to take the long way around which creates a voltage potential at the slot.  Think of the unconnected perimeter of the door as a slot antenna.
The frequency content of an EMP drops off pretty quick above 300MHz (1 meter wavelength) so if you were to make electrical connections every foot or less around the perimeter it would work great.

All that said, even with the imperfect electrical seal around the door, a shipping container would definitely provide some protection.  It just wouldn't be perfect.

[km4mcm]

Ok thanks. I appreciate your input I'm in the dark on the subject. 

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