Ohio State University engineers have invented a radar system that is virtually undetectable, because its signal resembles random noise. Like traditional radar, the "noise" radar detects objects by bouncing a radio signal off them and detecting the rebound. The hardware isn't expensive, either; altogether, the components cost less than $100.
The radar can be tuned to penetrate solid walls -- just like the waves that transmit radio and TV signals -- so the military could spot enemy soldiers inside a building without the radar signal being detected, Walton said. Traffic police could measure vehicle speed without setting off drivers' radar detectors. Autonomous vehicles could tell whether a bush conceals a more dangerous obstacle, like a tree stump or a gulley.
The radar is inherently able to distinguish between many types of targets because of its ultra-wide-band characteristics.
With further development, the radar might image tumors, blood clots, and foreign objects in the body. It could even measure bone density. As with all forms of medical imaging, studies would first have to determine the radar's effect on the body.