How to Block a Cell Phone GPS Signal With Foil

Lightning image by professional from

While cell phones are high-tech devices, their operating principles have been well understood for a century. With this basic science experiment, you can demonstrate how your mobile phone works by stopping it from receiving any signals, including GPS. This experiment works because you use aluminium foil to build a Faraday cage, a device that absorbs most electromagnetic (EM) waves in the same way than an antenna does.

Make a small hollow sphere from the aluminium foil, ensuring that the sphere is large enough to fit the phone inside. Leave a small opening so that you can take the phone in and out of the shell.

Take one end of the copper wire and secure it with electrician's tape to the faucet of your kitchen sink. This ground connection will prevent EM signals from affecting anything inside the foil.

Tape the other end of the wire to the aluminium sphere.

Turn on the cell phone and note its signal strength. Place the phone inside the cage and its signal will drop to zero, demonstrating the effects of a Faraday cage. The phone's GPS will cease to function.

Most recent