RF heating was understood well before the development of the cavity magnetron; Westinghouse demonstrated RF cooking at the 1933 World's Fair using a standard sh

RF heating was understood well before the development of the cavity magnetron; Westinghouse demonstrated RF cooking at the 1933 World's Fair using a standard shortwave transmitter. The chocolate bar story is attributed to Percy Spencer in 1945 and is probably somewhat fanciful - anyone working around high-power radar equipment would necessarily be aware of RF heating, because it presents a significant safety hazard. Spencer can legitimately claim to be the inventor of the microwave oven and is named on Raytheon's patent. https://patents.google.com/patent/US2495429A/ https://patents.google.com/patent/US2495429A/