https://www.sciencedaily.com/releases/2018/05/180524081722.htm > "Until now, this was considered impossible," said C.R. Selvakumar, an engineering professor at the University of Waterloo who proposed the concept several years ago. > High-frequency microwaves carry signals in a wide range of devices, including the radar units police use to catch speeders and collision-avoidance systems in cars.