Key Takeaways

  • The Physics: A Faraday Cage is a mesh of conductive material (copper, aluminum) that distributes external electrical charges around its exterior, canceling the field inside.
  • The Bag: A Faraday Bag is a portable cage. Phone in > Signal dead. No GPS, No WiFi, No Calls. Perfect for meetings or travel.
  • Key Fob Protection: Car thieves use "Relay Attacks" to amplify your key fob signal from inside your house to your car. Putting your keys in a Faraday box stops this.

You can put your phone in "Airplane Mode," but the GPS chip might still spy on you (E911 requirements). The only way to be 100% sure a phone is silent is to block the physics of the wave.

Uses cases

1. Anti-Tracking

Journalists and activists use them when meeting sources to ensure their location history doesn't place them at the scene.

2. Digital Forensics (Evidence Bag)

When police seize a phone, they immediately put it in a Faraday bag. This prevents the suspect from sending a "Remote Wipe" command to the phone before it can be analyzed.

3. EMP Protection

A high-quality Faraday Cage can theoretically protect electronics from an Electromagnetic Pulse (EMP) or severe solar flare, which would fry unshielded circuits.

Microwave Test

A common (but dangerous) test: Put your phone in the bag, put the bag in the microwave (DO NOT TURN IT ON). Call the phone. If it rings, the shielding is bad. Microwaves operate at 2.4GHz, same as WiFi/Bluetooth.

Frequently Asked Questions (FAQ)

Will aluminum foil work?
Yes, if you wrap it in 3-4 layers tightly. But it tears easily. A dedicated bag with conductive fabric is more durable and reliable.
Does it drain battery?
Yes. Fast. Your phone will panic because it has no signal, and it will pump maximum power to the antenna trying to find a tower. Turn it off before bagging it if you want to save battery.

Who is watching you?
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