What it was is enough.
Sources and reporting notes:
Patent US 2,292,387, “Secret Communication System,” Hedy Kiesler Markey and George Antheil, filed June 10, 1941, granted August 11, 1942. Consulted at patents.google.com. All technical details of the mechanism (condensers, paper strip, pneumatic control head, false channels, synchronization, steering tones) derive from this primary document.
George Antheil, Bad Boy of Music (Doubleday, 1945). Primary source for Antheil’s account of the collaboration, his description of Lamarr’s intelligence, and the wartime dinner-party conversation.
The National WWII Museum, “Hedy Lamarr’s WWII Invention Helped Shape Modern Technology,” nationalww2museum.org. Historical synthesis consulted for Navy response, sonobuoy adoption, Cuban Missile Crisis deployment.
MakeTechEasier.com, “Hedy Lamarr, George Antheil, and Frequency Hopping.” Consulted for legacy technology timeline, EFF award, Antheil’s reported speculation about Navy rejection.
MIT Lemelson Center, lemelson.mit.edu. Consulted for recognition history.
Jewish Women’s Archive (jwa.org). Consulted for biographical details of Lamarr’s Vienna upbringing and marriage.
Biography.com. Consulted for career chronology, marriages, later life.
Engineering and Technology History Wiki (ETHW). Consulted for note that Mandl “introduced her to the underlying idea.”
The Electronic Frontier Foundation Pioneer Award was given in 1997 to both Lamarr and Antheil. Lamarr’s son accepted on her behalf.
National Inventors Hall of Fame induction for both Lamarr and Antheil occurred in 2014.
The Bombshell: The Hedy Lamarr Story documentary (2017, dir. Alexandra Dean) was not directly screened for this article but is cited as a widely available source for the popular account.
The SS City of Benares was sunk September 17, 1940. Henry W. Antheil Jr. was killed June 14, 1940.