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WiFi Camera Generates Images From RF


When trying to optimize an antenna's position in a room, have you ever wished for the ability to see RF the same way we see light--with all bright spots and shadows revealed?

Bengt Sjölén, Adam Somlai Fischer, and Usman Haque have built a very ominous looking device that illuminates an area with RF and captures them on a panoramic "RF camera" that comes close. The device uses an array of "cantennas" made from spice cans, some motors and a netbook computer as a controller.

A video is available showing the device in operation and construction details.

The builders explain how it works:

"Radio waves at WiFi's wavelength behave similar to light in that they are reflected off almost all solid objects to varying degrees, just as when we see colors we see the light from a light source being reflected off an object into our eyes. And, just as with light, some materials are opaque and some materials are more or less transparent."

They further explained that they could do this RF visualization by pointing an antenna or multiple antennas and then measuring the resulting signal strength. They use this information to create full-screen images.

Could such a device be used to show the best spot for an antenna in an office building?

I would say yes for transmitting antennas, but just as you can't see the light in a room unless you're looking at the source or something that reflects it (walls, dust in the air, tables, chairs) the same limitation would apply to the WiFi camera. Perhaps someone will build one of these with larger antennas and circuitry designed to detect UHF TV signals.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.