Why Does Wi-Fi Use the Same Frequency as Microwaves?
When you start your microwave, do you lose Wi-Fi signal on a nearby device? Wi-Fi and Microwaves both operate on a similar frequency, which can lead to interference. But why? And if that’s the case why doesn’t Wi-Fi cook you?
Microwaves and Wi-Fi Use the Same Unlicensed Spectrum
In 1947 the International Telecommunication Union established the ISM bands, short for Industrial, Scientific, and Medical. The goal was to define what devices would be allowed to run at certain bands of radio frequency so that they wouldn’t cause interference with other radio communication services.
The ITM designated the 2.4 GHz band as an unlicensed spectrum specifically for microwave ovens. This band has three compelling properties: It doesn’t require much power to broadcast, it’s easy to contain, and at relatively lower power it can heat food. All this lowered the cost and barrier of entry for consumers.
As the ISM name suggests, the original intention was for use only in devices that didn’t provide communication. In the years since the prospect of an unlicensed spectrum has been used outside the original purpose, such as cordless phones, walkie-talkies, and more recently Wi-Fi. The 2.4 GHz band was ideal with its low cost to implement, lower power needs, and decent distance capabilities.
Microwaves Aren’t a Faraday Cage; They Leak
Anything that runs on the ISM bands is supposed to be designed for intolerances to avoid interference, and Wi-Fi devices do have algorithms expressly for that purpose. However, a microwave is powerful enough to overwhelm any nearby Wi-Fi signals.
Microwaves have shielding to prevent this, but they aren’t a perfect Faraday cage. The very nature of a mesh window on the door prevents that. It isn’t uncommon to have some leakage from a microwave—just look at one that hasn’t been cleaned in a while to see that. You’ll likely see grime and grease on the outside that could only have come from food on the inside. If it can leak solids, then it can leak radio waves too.
Microwaves and Wi-Fi devices use a similar enough frequency that one can interfere with the other. Your Wi-Fi won’t do anything noticeable to the microwave of course, in part because of its shielding and in part because all it is trying to to do is heat your food.
No Wi-Fi Can’t Cook You
