By Charles Henry
Everybody throws around the term “Faraday shields” or Faraday cages, but let’s be specific about what it is and how it is a must item for preppers.
Named after an expert in electricity, Mr. Faraday, the Faraday shield is a highly important item that is easy to build and vital for the protection of your delicate electronic equipment like radios.
Modern electronics, like a walkie talkie or the ignition system in your new car,* operate at very low voltages inside the box of circuits. The electronic parts inside, like chips or integrated circuits, can not survive large electrical pulses—conditions as simple as high static electricity and as complex as strong electric fields and especially EMP pulses like that from an atomic explosion or CME radiation from a storm on the Sun. Delicate electronics, and that means everything today, must be protected from strong electric fields. One exposure to a big discharge or pulse, and POOF your extensive collection of radios are turned into junk.
Whatever item you have that has delicate low-voltage parts inside—radios, cel telephones, bugs and bug sniffers, televisions, video and digital cameras, and computers and the like—must be protected. Dangerous pulses travel through the air like radio waves, are invisible, and not detectable in advance. You will not feel them. You can not reliably guess when pulses may come; they travel near the speed of light and provide no advance warning. Thus, you must store your electronic items inside a Faraday shield.**
A Faraday shield can easily be made by you at home. The goal is to make a box of metal that completely encloses all the delicate items you have. A simple example is to build a frame of wood or metal, say a two foot cube, and wrap that frame totally in copper window screen, the copper kind of screen that keeps flies out of your home windows. Include an opening lid. Tightly nail or clamp all joints so there are no gaps in the screen. Be sure the lid closes and makes tight contact around its edges with the screen around it. Attach a AWG 16 copper wire tightly to the screen to create a ground wire (long enough to attach to a ground rod).
The result you want is to have the screen block incoming pulse. You put your electronics inside the shield and leave them there. You may use a small wire to penetrate the shield to use to charge up the batteries while in the shield cage, but making any opening must be very small and sealing around it is necessary. The shield can be stored anywhere dry.
Test your Faraday shield by putting a walkie talkie inside the shield with it on receive. That is, the walkie talkie should be making background noise. Nearby, transmit with another walkie talkie to see if the one in the shield receives the signal. If the radio inside the shield hears nothing, your Faraday cage is done. You can also use a portable AM radio, tuned to a station. If the AM radio stops playing when inside, then the shield is ok. The grounding of the cage is an added step sometimes not necessary but a precaution.
Some preppers will use a new metal garbage can as a Faraday shield. That should work good if the lid makes total electrical contact with the can all around the edges. The point is to enclose the electronics completely with metal.
You could wrap individual items in metal, like the copper screen but not thin foil, but because the item must be totally covered, it will not function. A prepper may think he could wrap the body of his walkie talkie, but with the antenna sticking out, the radio will be killed by the kinds of pulse we are talking about.
Old tube-style radios and very old cars or trucks are less delicate for pulse attack. Those items have their own draw-backs as you should know, but at least they have a fighting chance of surviving pulse.
There is no escaping the damaging effects of pulse unless you are underground or in a shielded building. You will just have to have a Faraday shield to prepare for that awful future day which we all pray will never happen.
*Modern vehicles, your car or truck, have electronic ignitions and other wiring that is in danger of being knocked out from an electrical pulse. Most studies say that the car will be completely disabled—it dies, it will not start, it will not run—and the damage is permanent. The car battery will still be useful, but the car is dead. Shielding a vehicle is not easy; it would involve placing it inside a Faraday shield that totally encloses it—top, bottom, and all sides. Too, if the vehicle is in use and is hit, you can strip it for parts, but its electronics are fried forever.
Some concern needs to address your motor generator, the thing that has a gasoline motor that generates 120 volts of AC that can run your appliances. Like a non-electronic motorcycle, a generator is very simple and not likely to be affected by pulse. However, attached electric extension cords can act as antenna to feed pulse back to the generator, so it is better to have it unplugged and turned off to be super safe. See the irony noted below.
**An ironic fact is that if your electronic device is IN USE and thus out of your Faraday shield, it will be damaged. This fact provides the prepper with a real dilemma. Inside the shield, the items will not function. Outside the shield and in use, the items are in danger of pulse destruction. Thus, it helps to have back-up copies of your electronics, one inside the shield and one in use. It is highly unlikely you will receive more than one pulse, so once the pulse flashes, you can take all the gadgets out for full use.
CMEs from the Sun do give warnings which scientists can tell people about. However, the damage of huge CMEs is so great that storing electronics immediately upon any warning is a very good idea.