Yoji Ito (伊藤 庸二, Itō Yōji, 5 March 1901[1]–9 May 1955[2]) was an engineer and scientist who had a major role in the Japanese development of magnetrons and the Radio Range Finder (RRF – the code name for a radar).

In late 1932, believing that the magnetron would eventually become the primary source for microwave power, he started his own research in this technology, calling the device a magnetic electric tube.

In 1937, they developed the technique of coupling adjacent segments (calling it push-pull), resulting in frequency stability, an extremely important magnetron breakthrough.

[3][4] Shigeru Nakajima,[5] a younger brother of Yoji Ito and a scientist at the Japan Radio Company (JRC), was also investigating magnetrons, primarily for the medical dielectric heating (diathermy) market.

Staying several months, he became aware of their pulse-modulated radio equipment for detecting and ranging, and immediately sent word back to Japan that this technology should be incorporated in the NTRI-JRC effort.

On August 2, 1941, even before Ito returned to Japan, funds were allocated for the initial development of a pulse-modulated Radio Range Finder (RRF – the Japanese code name for a radar).

[7] In parallel with the VHF work, Yoji Ito also returned to the magnetron applications, resulting in Japan's first pulse-modulated microwave RRF set.

Yoji Ito and others eventually came to believe that this device might be used as a weapon, encouraged by an earlier newspaper article telling of Nikola Tesla inventing a beam that would "bring down squadrons of aircraft 250 miles away."

Scientists and engineers, as well as military technical officers, engaged in communications and radar formed the base for Japan's future electronics industry.

In 1947, with the hope of making a peaceful contribution of technologies cultivated in his naval days, Dr. Ito founded the Koden Electronics Company Co., Ltd., an affiliate of JRC.

Among early products that they conceived was a series of radio direction finders for use in small boat navigation, along with an electronic fish-finder that revolutionized the Japanese commercial fishing industry.