German Engineers use Wifi to see through walls

German Engineers use Wifi to see through walls

Engineers at the Technical University of Munich (TUM) have developed a holographic imaging process that depicts the radiation of a Wi-Fi transmitter to generate three-dimensional images of the surrounding environment allowing you to “see” through walls

The technology is surprisingly simple and exploits Wi-Fi’s ability to pass through walls.

By using two antennas engineers were able to record a Wi-Fi field around a particular room. Each antenna then captures the intensity and the “phase” of the Wi-Fi field to detect the places it bounces off from.

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The set-up of the WLAN-holography experiment

The result. A holographic image of the room (which might not be that vivid – yet) proves that the concept works in practice rather than just theory.

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This cross – made of aluminum foil – can easily be reconstructed from the WLAN-hologram as can be seen in the inserted picture

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A simulation of a warehouse from the “light” of the WLAN router in the basement, the three-dimensional image

Privacy Issues

The ability to see through walls might be unsettling but Friedemann Reinhard, one of the inventors of the technology, explains “[while] this raises privacy questions [..] it is rather unlikely that this process will be used for the view into foreign bedrooms in the near future. For that, you would need to go around the building with a large antenna, which would hardly go unnoticed. There are simpler ways available.”

Instead, the technology will probably have life-saving applications. It is hoped that it might be an asset to rescue operations after a disaster (such as an earthquake or an avalanche). With the technology mobile enough to be placed on a truck which could be driven around the rubble or debris to search for survivors.


Philipp M. Holl and Friedemann Reinhard: Holography of Wi-fi Radiation. Physical Review Letters, 05.05.2017 – DOI: 10.1103/PhysRevLett.118.183901

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