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). Early years Yoji Ito was born and raised in Onjuku, then a fishing village in the Chiba Prefecture of Japan. His father was the primary schoolmaster and encouraged his children to achieve science and mathematics excellence. After graduating in electrical engineering from the Tokyo Imperial University, Ito was commissioned in the Imperial Navy and spent several years in assignments at sea. At the NTRI Still in the Navy, Yoji Ito was sent to Germany for graduate study where he was a student of Heinrich Barkhausen at the Dresden Technische Hochschule. Upon completing his Doctor of Engineering degree there in 1929, he was promoted to the rank of Commander and assigned as a researcher at the Naval Technology Research Institute (NTRI) in the Meguro area of Tokyo. The NTRI had been formed in 1922, and was just becoming fully operational when Ito was sent there. Here first-rate scientists, engineers, and technicians were engaged in a wide variety of activities for advancing naval capabilities. At NTRI, Ito became involved with analyzing long-distance radio communications, and wanted to investigate the interaction of microwaves with the Kennelly–Heaviside layer (the ionosphere). He started a project using a Barkhausen–Kurz tube, then tried a split-anode cavity magnetron developed by Kinjiro Okabe at Tohoku University, but the frequency was too unstable. 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. Partnerships Tsuneo Ito (no relationship to Yoji Ito) at Tokoku University developed an 8-split-anode magnetron that produced about 10 W at 10 cm (3 GHz). Based on its appearance, it was named Tachibana (or Mandarin, an orange citrus fruit). Tsuneo Ito joined the NTRI and continued his research on magnetrons in association with Yoji Ito. In 1937, they developed the technique of coupling adjacent segments (calling it push-pull), resulting in frequency stability, an extremely important magnetron breakthrough. Shigeru Nakajima, 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. An alliance was made between NTRI and JRC for further magnetron development. In early 1939, led by Yoji Ito they built