The Movie Star Who Patented a Secret Weapon the Navy Rejected

What happened?

Lamarr was born Hedwig Eva Maria Kiesler in Vienna in 1914. At 19, she married Friedrich “Fritz” Mandl, one of Austria’s largest arms manufacturers, and spent several years at his side in meetings with military engineers and munitions clients, absorbing details of weapons design she was never meant to keep. In 1937 she left the marriage and Austria, signed with MGM, and reinvented herself in Hollywood as Hedy Lamarr, one of the most recognizable faces in American film.

Acting was not her only interest. Lamarr kept a drafting table in her home and spent her off-hours sketching inventions — an improved traffic signal, a tablet that would dissolve in water to make a soda-like drink. By 1940, with German U-boats sinking Allied ships and radio-controlled torpedoes vulnerable to enemy jamming, she turned her attention to a military problem. If a torpedo’s guidance signal broadcast on a single radio frequency, an enemy could simply find that frequency and drown it out with noise. Lamarr’s idea, drawing on what she’d absorbed from Mandl’s world, was to make the guidance signal impossible to pin down by having it jump unpredictably between many frequencies.

She brought the concept to George Antheil, a composer she knew socially, whose 1924 piece “Ballet Mécanique” had used a bank of synchronized player pianos. Antheil suggested using the same kind of mechanism — a punched paper roll, like the ones that drive a player piano — to synchronize a transmitter and receiver so both hopped between the same sequence of frequencies at the same instant. With engineering help from Caltech’s Samuel Mackeown, they refined the idea into a working design using 88 frequencies, the same number as keys on a piano. They filed for a patent in June 1941, and it was granted on August 11, 1942.

The Navy did not adopt it. According to Lamarr’s own later account and subsequent historical research, naval officers concluded the mechanical player-piano-style system was too bulky to fit inside a torpedo, and some accounts suggest Lamarr’s status as a foreign-born woman, not yet a U.S. citizen, worked against the idea being taken seriously. When she offered her services to the National Inventors Council, she was reportedly told she could better serve the war effort using her fame to sell war bonds — which she then did, headlining bond drives that raised millions of dollars. The patent expired in 1959, unused and uncompensated.

Why was it strange?

Lamarr was, at the time, routinely described in the press as one of the most beautiful women in the world — a label that came with the assumption she had little else to offer. She reportedly said, “Any girl can be glamorous. All you have to do is stand still and look stupid.” The idea that a working weapons engineer’s mind sat behind that image, developed alongside a composer whose main claim to fame was a piece for player pianos, upended the era’s expectations twice over: about what a movie star was capable of, and about where a breakthrough in military communications might come from.

What did scientists learn?

The Lamarr-Antheil patent laid out what engineers now call frequency-hopping spread spectrum: a method of spreading a radio signal across many channels in a pattern known only to the sender and intended receiver, so that jamming or eavesdropping on any single frequency reveals almost nothing useful. The underlying insight — that synchronization, not raw signal strength, is what makes a channel secure — became foundational to spread-spectrum communications more broadly.

The idea didn’t disappear after the Navy passed on it. In the mid-1950s, engineers at Sylvania Electronic Systems, working with lightweight transistors that hadn’t existed in 1942, adapted the concept for sonobuoys, devices dropped from aircraft to detect submarines. A frequency-hopping system built on these principles, known as BLADES, was installed aboard the USS Mount McKinley, flagship of the naval blockade during the 1962 Cuban Missile Crisis — twenty years after Lamarr and Antheil’s patent was granted, and three years after it had expired.

How does it affect us today?

Spread-spectrum techniques descended from this idea now underpin large parts of modern wireless technology. Bluetooth, which connects headphones, keyboards, and countless other devices, uses frequency hopping directly. It’s worth being precise here: Lamarr is often credited with “inventing Wi-Fi,” but that overstates the connection — early Wi-Fi (802.11) briefly used frequency hopping, but the standard that became dominant, 802.11b, dropped it for a different spread-spectrum method. The fairer claim is that Lamarr and Antheil’s patent helped establish the conceptual foundation that GPS, secure military radios, and Bluetooth all build on, even where the specific technique diverged.

Recognition came slowly. Lamarr received no royalties and little acknowledgment during her lifetime for the invention. In 1997, she and Antheil (posthumously, in his case) received the Electronic Frontier Foundation’s Pioneer Award. In 2014, both were inducted into the National Inventors Hall of Fame — Lamarr fourteen years after her death.

Fun fact

Lamarr and Antheil chose 88 hopping frequencies because that’s the number of keys on a standard piano — a direct nod to the player-piano mechanism that inspired the whole design.

Sources

• U.S. Patent 2,292,387, “Secret Communication System,” Hedy Kiesler Markey and George Antheil, filed June 10, 1941, issued August 11, 1942 — Google Patents
• National Inventors Hall of Fame: Hedy Lamarr
• Smithsonian Magazine: “Thank This World War II-Era Film Star for Your Wi-Fi”
• The National WWII Museum: “Hedy Lamarr’s WWII Invention Helped Shape Modern Tech”
• IEEE Standards Association: “Actress/Inventor Hedy Lamarr – and How Far Wireless Communication Has Come”