Faraday Cage vs. Faraday Bag: Which Is Better?

There are many different products on the market that claim to provide the best EMP protection. Two of the most popular are Faraday cages and Faraday bags.

Faraday cages vs. Faraday bags, which is better? Both Faraday cages and bags are able to provide a similar level of protection for your electronics, assuming they’re made to meet the same quality standards and specifications. But we personally feel that Faraday bags are superior. They’re more compact and just a better option at a lower price point.

In this article, you’ll learn the differences between a Faraday cage and a Faraday bag. As well as our opinion of which is better, and what kinds of electronics you can store in them.

What Is A Faraday Cage?

A Faraday cage is a closed structure that’s used to block electromagnetic fields, including those from an EMP attack. It can be a solid covering, or a mesh.

The first Faraday cage was invented by Michael Faraday of England in 1836. Although some argue that Benjamin Franklin actually observed the phenomenon first in 1755.

A Faraday cage can protect all kinds of electronic equipment from EMP damage, as well as against radio interference and most kinds of cyber attacks. They can even be used to help protect people from things like lightning strikes, since the exterior of the cage conducts all of the electrical current.

Sometimes entire rooms or even buildings can be made into a Faraday cage. This is especially used by governments and militaries to protect sensitive technologies and information.

Fun Fact: Faraday cages can’t block the Earth’s magnetic field, so a compass will still work inside of them!

You probably use technology based on Faraday cages every day without knowing it.

Microwave ovens use a Faraday cage to keep electromagnetic energy inside and protects the person using it from radiation. If you look at the glass window on the front of your microwave, you’ll see a metal mesh which is part of the microwave.

Computer and TV cables such as USB cables or HDMI cables use shielding based on the same principals of a Faraday cage. This shielding prevents the signal being transmitted from leaking out of the cable.

Downsides Of A Faraday Cage

Faraday cages are one way to protect your electronics, but they aren’t without their cons.

Expensive. Even a small Faraday cage can easily cost hundreds of dollars. They also tend to be heavy, so they cost more in terms of shipping and handling.

Bulky. A Faraday cage is large and usually has a rigid shape. That means even a small Faraday cage isn’t something that you can throw into a backpack to take with you. At least not without taking up most of your available space.

Quality varies. All kinds of shops and websites sell items that they claim to be Faraday cages. Some of these are reputable and sell products that actually work. Others won’t actually provide any kind of protection for your devices. And the bad news is that you likely won’t know which is which until it’s too late and an EMP event has already occurred.

Sadly many people on YouTube have made videos showing how a metal container will stop radio signal. Unfortunately EMP waves and handheld radios are not putting out the same kind of frequencies and so that is a very ineffective way to test EMP protection. At Tech Protect Bags we only use real testing equipment designed for EMP testing.

What Is A Faraday Bag?

A Faraday bag is based on the same principles as a Faraday cage, but it’s a more updated and modern version. It’s a bag made from a material capable of blocking electromagnetic signals. Using special sealing techniques like dual paired seam construction, they can be used to hold electronics and prevent external signals from interfering with devices.

A Faraday bag is able to block cell signals, satellite, Bluetooth, and wifi frequencies.

Tech Protect Mil-B-81705-Rev-C EMP bags are made using the latest metalizing technology. They’re only 7 mm thick, but provide some of the highest levels of strength and protection around.

They’ve even been successfully used by NASA!

Why Are Faraday Bags Better Than Faraday Cages?

We feel that Faraday EMP bags can do everything that a Faraday cage can do, but in a smaller and cheaper option.

They’re inexpensive. You can get Faraday bags for much cheaper than it would cost to buy a Faraday cage, or even try to make one yourself!

You can get a medium sized (8″x16″) Faraday bag for under $10! That’s enough to hold portable radios, power strips, charging stations, and other small electronics.

For around $100 you can get a Faraday bag big enough to hold large LED TVs, solar panels, or even a 5,000-watt generator.

They’re light and flexible. A Faraday bag can bend and expand to fit different kinds of objects, but it has a very small profile when empty so you can easily store it. Unlike a homemade Faraday cage that you might try to make out of a metal garbage can, which will take up a corner of your garage or basement.

You can put a Faraday bag inside of your bug out bag. Or even put one Faraday bag inside of another for a second layer of protection.

Fun Fact: ESD bags are not the same as EMP bags. ESD bags do not stop EMPs.

Uses For Faraday EMP Bags

Faraday bags are a great way to protect your valuable electronics during an EMP attack. But they have other uses as well.

You can use a Faraday bag to shield your cell phone, laptop, tablet, or credit cards from fraudsters and identity theft. Modern scammers use skimmers that can be used to steal your data just by passing them within a few inches of your electronics. A Faraday bag will ensure no signals get in – or out! This is important if you’re in busy places like grocery stores or shopping malls.

Governments, military, and spy organizations can use Faraday bags to protect data, including prevention of unwanted cell phone or wifi transmissions inside of secure locations. Or tracking of such devices.

Police are using Faraday bags more and more to preserve laptops, cell phones, and other kinds of electronics that might be used as evidence. This helps prevent the devices from being remotely wiped of incriminating evidence using an EMP or even services like iCloud. GPS signals, texts, emails, and calls can’t leave or enter a device that’s inside of a Faraday bag.

Faraday Bags vs Mylar Bags

Some people incorrectly refer to mylar bags as Faraday bags, when in reality they aren’t nearly as effective.

A mylar bag is made of polyester resin that has been coated with aluminum. They’re usually about 3.5mm thick.

A Faraday bag is made up of multiple layers and materials including polyethylene plastic, polyester, and aluminum. A Faraday bag is typically 7mm thick, which is twice as thick as a mylar bag. The polyethylene plastic serves as the main insulator inside the bag to make sure items within the bag do not touch the metal layer of the bag.

Not only does a Faraday bag provide better protection from electromagnetic signals, but from light as well.

A mylar bag might offer some protection, but there’s no guarantee it will block GPS< wifi, cell phone, RFID, RFI (radio-frequency interference) or other signals. They’re only designed to cancel out light electromagnetic interference.

Faraday bags provide a superior level of protection and are made to protect against EMP attacks and other strong forms of electromagnetic interference, not for food storage.

Tech Protect Faraday EMP bags can also be used to keep items away from water. In the devastating hurricanes and flooding that has happened in the southern states, many people have gone back to their flooded homes to find their electronics within their Tech Protect bags were 100% dry.

What Kind Of Items Should You Store In A Faraday Bag?

Your options are only really limited by the size and number of Faraday bags that you’ve got. Generally it’s a good idea to protect any kinds of electronics that you think you might need after an EMP attack or failure of the electrical grid.

That includes things like

  • Solar chargers
  • Solar lights
  • Laptops and tablets
  • Cell phones
  • Walkie talkies
  • Different kinds of radios (AM/FM, shortwave, ham)
  • Memory devices like USB sticks and external hard drives
  • Alarm clocks
  • Glucose testers (if you or a family member has diabetes)
  • CPAP machines
  • Anything you would want to use during a long term power outage that has a chip in it.

Related Questions

Q: Why can’t I just wrap my electronic devices in tin foil?

A: You can, and it actually will provide some protection, but not nearly the same level as a Faraday bag. It might be an okay solution for less valuable electronics that you don’t need to use on a regular basis. But unwrapping your devices from multiple layers of aluminum foil every time you want to use them will quickly become a pain. Plus tinfoil tears easily. It’s much easier to have a Faraday bag that you can easily open and close to access your electronics. Also there is no insulator with tin foil, so the electrical charge could simply jump through the tin foil, using it as a conductor, and then hit the item that’s wrapped up.

Q: Can I use anti static bags that came with my computer hardware as a Faraday cage?

A: If you buy a computer hard drive or other sensitive electronics, they probably came in a blueish silver colored antistatic bag. Those don’t really provide the kind of protection you need against an EMP. They are called ESD bags and are only meant for very low amounts of voltage.

They’re partly transparent, so they don’t block electromagnetic energy in visible wavelengths. These kinds of bags are only made to protect against static electricity. Their coating is only slightly conductive, and isn’t good at protecting against much else.

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