By Andrew Liszewski
A few years ago, at CES2010, we discovered a concept device that RCA was showing off that promised to harvest electricity from wi-fi signals, which could then be used to charge mobile devices. The ‘Airnergy’ charger, as they called it, sparked a lot of discussion about whether or not such a technology was even possible. And sure enough, at CES 2011, the Airnergy devices were no where to be seen at RCA’s booth. We assumed that would be the last we’d hear about the concept, but a Japanese company called Nihon Dengyo Kosaku has apparently picked up the torch.
Their unfortunately named ‘Rectenna’, which is actually a combination of the words ‘rectifying’ and ‘antenna’, is able to convert terrestrial TV broadcast signals, or wi-fi, back into usable electricity. At a recent trade show in Tokyo, where the company was showing off the technology, they were able to harvest about 1.2mV and 0.06µW of power from a TV broadcast antenna located about 3.4 miles away. Not a heck of a lot of juice of course, but there are electronics that can run on just micro-watts of power. So while it won’t be useful for charging your smartphone, it does seem to be a viable way to wirelessly power certain barebones devices.