Margen
One of the most famous actresses of 1940s Hollywood patented a military system for secret communication. Her name was Hedy Lamarr, and her ideas still echo today in technologies like Wi-Fi and Bluetooth.
At the height of the Second World War, in 1942, Lamarr and the composer George Antheil filed a patent for guiding torpedoes by radio without the enemy being able to jam the signal. Their trick: making transmitter and receiver hop constantly from frequency to frequency, in a coordinated way, like a secret melody. Anyone listening to a single frequency would hear almost nothing.
The Navy shelved the invention and Lamarr never made a dollar from it. Decades later, that family of techniques, spread spectrum, became fundamental to wireless communications. Recognition came very late: she entered the National Inventors Hall of Fame in 2014, fourteen years after her death.
Source: National Inventors Hall of Fame