# WiFi Signal Strength

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#### Updated on Aug 23, 2013

When wireless signals leave a WiFi hotspot and travel to a computer or other wireless device, the wifi signal strength decays as it passes through air or solid objects. This is why a computer may be unable to pick up the signal from a hotspot that is more than a couple of rooms away. The amount that the wifi signal falls off depends on the medium it passes thorough; for example, whether it passes through a wall, door or window.

This project requires measures wifi signal strength as it passes through air and solid objects.The goal is to have the student collect an analyze experimental data in order to reach an understanding of how wifi signal strength is affected by various materials.

### Materials:

• The experiment requires wireless access to the Internet (a WiFi hotspot). Ideally the student will own or be able to borrow a wireless device (e.g., personal computer, video game console, smartphone, or digital audio player) that displays WiFi signal strength. If this is not the case, a standalone wireless detector may be purchased.
• Wireless devices that connect to the Internet and WiFi hotspots are present in many homes. WiFi hotspots are accessible in many homes as well as business establishments outside the home. Inexpensive WiFi detectors can be purchased on the Internet.

### Procedure

1. Measure the WiFi signal strength at the hotspot and at several other places within signal range. Note where the signal is no longer detectable.
2. Propose a model (hypothesis) for how signal strength varies at locations away from the hotspot.
3. Use the hypothesis to predict the signal strength in an untested location, for example, outside your house.
4. Test your hypothesis by measuring the signal at the new location.
5. Accept or revise your hypothesis based on your findings. If you revise the hypothesis, use it to make a new prediction that you can test.

Sample table. Relative attenuation of a signal after passing through various materials

 Material Relative signal strength Plasterboard wall `0.50` Glass window `0.50` Cinder block wall `0.40` Metal door `0.25`

Dr. Frost has been preparing curriculum materials for middle and high school students since 1995. After completing graduate work in materials science at the University of Virginia, he held a postdoctoral fellowship in chemistry at Stanford. He is the author of The Globalization of Trade, an introduction to the economics of globalization for young readers.