Can the Microwave Really Scramble My Wi-Fi?

A handy guide to the electromagnetic interference happening in your home.

By Rachel Z. Arndt


November 21, 2013 12:00 PM Text Size: A . A . A

Whenever I turn on my microwave, my AirPlay speakers cut out. Coincidence?

Probably not—your microwave is the likely culprit. Because AirPlay speakers receive signals over a wireless network, they're susceptible to interruptions from other electronics. And most microwaves and wireless signals operate in the same part of the radio spectrum, 2.4 GHz for routers and 2.45 GHz for microwaves. Though the majority of a microwave's energy is kept bouncing inside the box's metal walls, a tiny bit can get out. Even that bit can interrupt a wireless signal, which is beamed at about 28 milliwatts, a sliver compared with a microwave's 1000 watts. "An analogy would be having a conversation with a soft-spoken person in a crowded room," says Steven Spangler, professor of physics and astronomy at the University of Iowa. "You are trying to listen to the faint signals from the person with whom you want to talk, but it is being drowned out by the loudmouth a few feet away. It is hard to detect a signal in the presence of large, variable noise."

The easiest solution is to move your router and speaker at least 10 feet away from the microwave. But if that's not possible, and if you own a non-AirPlay speaker plugged into an AirPort Express, you can try a dual-band router, which can transmit in either 2.4 GHz or 5 GHz. Simply have the AirPort Express operate at 5 GHz so that it's occupying a different part of the spectrum. Finally, if you don't want to pony up for a new dual-band router, you can try changing the settings on your existing one. Access your router's Web page (usually you can find this by typing into a browser) and adjust the settings for the router's Wi-Fi channel based on the frequency of your microwave, which probably is listed in a label on its back. For example, channel 11 puts a router at 2.462 GHz, and channel 1 at 2.412 GHz—so to eliminate interference from a microwave that operates at 2.450 GHz, you'd prefer channel 1. This should fix the problem—though sometimes even devices operating in nearby channels can cause interruptions.

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