How to Make Your Own Faraday Cage

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How to Make Your Own Faraday Cage

You can buy Faraday cages, but what fun is that? Whether you want to keep your devices secure during a protest or are just prepping for doomsday, here's how to shield your gadgets from electromagnetic fields.

 

 

Protests against police brutality are currently taking place across the country, and while technology has been helpful in organizing them, it can also be used against those in attendance. Facial recognition can be used to identify (or misidentify, as often happens) protesters and phones can be surveilled.

 

If you're demonstrating, it's a smart idea to take steps to lock down your phone ahead of time or even just leave it at home. If the latter isn't possible, put it in a Faraday cage, an enclosure that shields against the entry or escape of electromagnetic fields.

 

A Faraday cage is useful for many circumstances. Perhaps you have a car with remote keyless entry, and want to prevent it from getting broken into by teens with a power amplifier. Or you don't want the NSA listening in on your conversations. Or you're a doomsday prepper just waiting for a gigantic, Earth-enveloping electromagnetic pulse to rise up in the sky and wipe out all electronic communication.

 

You can buy Faraday cages that vary in size from small bags that hold a smartphone to a Faraday tent under which you can park a car and probably your entire family.

 

If you'd rather not spend the money and think you can cook up a solution in your own kitchen using appliances, it's not that easy. It's commonly thought that a refrigerator or freezer can serve as an ersatz Faraday cage. But unless the seal is really tight, it's not likely to work. Likewise, a microwave oven also does not a Faraday cage make. A police precinct in Greenfield, Massachusetts, tried to prevent the remote wiping of phones it confiscated by placing them in microwave ovens. They found that only commercial-grade ovens worked.

 

There are still some things you might have on hand, though, that can be converted into a Faraday cage at little cost. Before you put your phone in one, though, put it in airplane mode, otherwise the battery will drain as it searches for a signal.

Think Small

If you're making a Faraday cage to take to a protest, your best bet is indeed to buy one. But you can make a small one.

 

The tinfoil hat joke comes from somewhere, and that somewhere is the Faraday cage. Aluminum foil can be used to protect against electromagnetic fields.

 

Shoplifters use this to their advantage by coating the inside of bags to prevent detection. The same principle applies into this Instructables about using aluminum foil, an envelope, and some tape.

File It Away

A metal file cabinet requires just a few tweaks to be turned into a Faraday cage. These directions on Instructables require just a few common pieces of hardware, some cables, and the cabinet itself.

This Is All Garbage

The solution could be in your own backyard. Metal garbage cans—with a bit of modification—can be effective Faraday cages.

 

Shake It Off

If all this talk of Faraday cages is stressing you out and you want a drink, stop! Your easiest solution is at hand with a cocktail shaker.

 

 

Testing 1-2-3

Whatever Faraday cage you choose, test it. Rigorous testing involves a software-defined radio receiver but you can do a simple test by tuning a radio to a station that comes in strong and placing it inside the Faraday cage. Close the cage and if you can still hear the station, the cage is not working.

 

PCMag