The aluminum foil trick for your Wi-Fi: Science confirms it

It may seem like an internet myth, but science backs it up: using aluminum foil can significantly improve your Wi-Fi signal. We'll explain the trick, based on a university study, so you can try it at home and optimize your connection.

In the quest for a stronger and more stable Wi-Fi signal, many have turned to homemade solutions that often hover between myth and reality. One of the most persistent is using aluminum foil to improve coverage. Surprisingly, this isn't just an unfounded folk trick; science has proven it works.

A team of researchers from the prestigious Dartmouth College, in collaboration with Columbia University and other institutions, not only validated the idea but also refined it. Their study demonstrates that a properly designed signal reflector can direct radio frequency waves to strengthen coverage in desired areas and weaken it in others, improving both network performance and security.

The antennas on most Wi-Fi routers are omnidirectional, meaning they emit the signal equally in all directions, like a light bulb illuminating a room. This is inefficient, as part of that signal is directed toward walls, windows, or areas where it's not needed, weakening it in the process.

Aluminum foil, being a metallic material, acts as a radio wave reflector. When strategically placed, it creates a sort of "virtual wall" that redirects signals that would otherwise be lost, concentrating them in the direction of your devices.

“With a simple investment of about $35 and specified coverage requirements, you can custom-build a wireless reflector that outperforms antennas costing thousands of dollars.” – Xia Zhou, assistant professor of computer science at Dartmouth and leader of the study.

The Dartmouth researchers didn't just wrap the router in aluminum foil. They developed an algorithm called WiPrint that, based on a home's layout and the areas to be covered, calculates the optimal shape of a reflector to maximize the signal. They then 3D-printed this shape and covered it with aluminum foil.

The results were overwhelming: they managed to increase the signal by up to 55.1% (6 dB) in the desired areas and reduce it by up to 63.3% (-10 dB) in areas where it was not needed, which also improves security by preventing the signal from "escaping" outside the home.

Even if you don't have access to a 3D printer and WiPrint software, you can apply the basic principles of this discovery easily and inexpensively.

• Cut a sheet of aluminum foil: You'll need a piece approximately 30 x 20 cm. You can use cardboard or cardstock to make it more rigid.
• Give it a curve: Fold the foil (with cardboard if using) to create a "C" or parabolic shape. The key is the curvature, which will help focus the waves.
• Place it behind the router: Place the aluminum reflector behind the router's antennas. The shiny side of the foil should face the router, and the curved "mouth" should point toward the area of your home where the signal is weakest (for example, your office or living room).
• Experiment with position: The location and angle of the reflector are crucial. Move the reflector slightly and run speed tests on your device to find the optimal position.

In addition to the aluminum trick, tech experts recommend other simple practices to optimize your network:

• Place the router in the center of the house: For more homogeneous coverage.
• Don't place it on the floor: Wi-Fi signals tend to radiate downward. Placing it on a table or shelf improves dispersion.
• Keep it away from other electronic devices: Microwaves, televisions, and monitors can cause interference.
• Adjust the antennas: If your router has external antennas, try placing one vertically and the other horizontally. This helps align the signal with your devices' internal antennas, which vary in position (for example, on a laptop vs. a smartphone).

This trick, far from being an urban legend, is a fascinating example of how a simple physical principle can offer a practical and accessible solution to an everyday problem.