Apple AirTags are $29 devices you place on an item—keys, wallet, backpack—and use to track them down should they be lost or stolen. But how does it work? It’s all thanks to a technology called ultra-wideband (UWB).
UWB is not new. Its appearance in the AirTags is akin to the actor who has a breakthrough performance in time for the Oscars after working for decades in Hollywood. Known as “pulse radio” in the early 2000s, UWB was all about fast, wireless data transfers. It tried to compete with Wi-Fi, but largely ended up in some limited medical and military equipment.
The name “ultra-wideband” comes from the ability to transmit info across a wide radio bandwidth, from 500MHz to several gigahertz. That gives it a short range. Ultimately, it’s a radio tech a lot like Wi-Fi and Bluetooth, but it doesn’t use the 2.4GHz frequencies. That makes UWB compatible with other wireless technologies—there’s no signal interference. It’s also low power and provides data in real-time thanks to pulses sent every other nanosecond.
That is why UWB excels at the job it has today: Finding things. The days of trying to use it for data communication are over. Today’s UWB can accurately pinpoint other devices, tell you if it’s in motion, and lead you to it. UWB can, in theory, pinpoint things down to the centimeter. Walls and other obstacles are not much of an issue.
Other real-world possibilities for UWB include using it in smart locks for passive, keyless entry, which means the tech can tell not only if you’re approaching, but also if you’re inside or outside the building or car. It could even start the vehicle for you. It could power a new wave of garage door openers that don’t require you to push a button. You could skip having a debit card when you approach an ATM, or carrying a credit card for payment since the robot in the drive-thru window will know you’re waiting for your fries and a shake. Sharing and data transfers, AirDrop-style, will take on entirely new dimensions with better location awareness, something Samsung is already working on with its Nearby Share app. UWB could even help us all keep a decent social distance of six feet via warnings to our devices.
Wi-Fi and Bluetooth can try, but neither can determine a location with the exactitude of UWB.
Plus, UWB is locked down. It has security extensions built right into the specification (the PHY layer of IEEE 802.15.4z, to be precise), so it can do random number generation and cryptography. What does that mean to you? You probably don’t need a VPN to secure your smart tracking tags, at the very least. That’ll be important if it’s unlocking your doors, as well as giving away your location.
This is mostly built on work being done by an industry group called the FiRa (fine ranging) Consortium. Ranging, in this case, means measuring. FiRa exists to grow the ecosystem of UWB products. Adoption by big-name companies in smartphones will do exactly that.
But there’s also the Car Connectivity Consortium and the UWB Alliance, which formed in 2018, ahead of FiRa. They all may have competing UWB tech out there someday, which would be unfortunate, but hopefully they’ll work together on different aspects of UWB.
UWB sensors were first built into the iPhone 11, plus Apple Watch Series 6, in 2019 as Apple prepared for the future, but not in all countries. Samsung started putting them in the Galaxy line with the Note 20, S21 Ultra 5G, and S21+, ready to work with its own SmartTag+. (The less expensive Galaxy SmartTag is Bluetooth-only.) China’s Huawei is also reportedly looking into it. At this point, expect that every company, even car companies, are looking closely at UWB.
Apple’s application of the tech is uniquely Apple-centric, of course. UWB’s range isn’t that much better than that of Bluetooth, around 30 feet, but Apple’s implementation means that if an AirTag is active around any Apple device with UWB built-in, the AirTag can still be tracked by the owner. (For more details, read our Apple AirTag review).
This is more relevant than ever, as new data indicates that more people want an item tracker than ever, now that Apple has made them appear legit. Sorry, Tile.
By the way, don’t confuse any of this with the branding on Verizon 5G Ultra Wideband. The mobile carrier is not using any kind of UWB technology with 5G.
