Ohio State University engineers have invented a radar system that is virtually undetectable, because its signal resembles random noise.

The radar could have applications in law enforcement, the military, and disaster rescue.

Eric K. Walton, senior research scientist in Ohio State's ElectroScience Laboratory, said that with further development the technology could even be used for medical imaging.

He explained why using random noise makes the radar system invisible.

"Almost all radio receivers in the world are designed to eliminate random noise, so that they can clearly receive the signal they're looking for," Walton said. "Radio receivers could search for this radar signal and they wouldn't find it. It also won't interfere with TV, radio, or other communication signals."

The radar scatters a very low-intensity signal across a wide range of frequencies, so a TV or radio tuned to any one frequency would interpret the radar signal as a very weak form of static.

"It doesn't interfere because it has a bandwidth that is thousands of times broader than the signals it might otherwise interfere with," Walton said.

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