Yoji Ito Early years . Yoji Ito was born and raised in Onjuku , 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 a 10 - cm ( 3 - GHz ) , stable - frequency Mandarin - type magnetron ( No . M3 ) that , with water cooling , could produce 500 - W power . Magnetron . The configuration of the M3 magnetron was essentially the same as that used later in the device developed by Boot and Randall in early 1940 , including the improvement of strapped cavities . Unlike the high - power magnetron in Great Britain , however , the initial device from the NTRI generated only a few hundred watts . During 1940 , Yoji Ito suggested that the magnetron be used in a microwave collision - avoidance system , assisting naval vessels to navigate in formation . The NTRI and JRC were funded for a demonstration , with the range ( distance ) to other vessels determined by frequency - modulating the magnetron . This effort was not successful , but it led to the NTRI attempting to find what the Germans were doing in this area . ( Japan had joined Germany and Italy in a Tripartite Pact in 1936 . ) VHF . In late 1940 . Commander Ito led a technical - exchange mission to Germany . Fluent in the German language and holding a doctorate from Dresden Technische Hochschule , he was well received . 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 ) . The Germans had not yet developed a magnetron suitable for use in such systems , so their equipment operated in the VHF region . At the NTRI , they followed the Germans and built a prototype VHF set operating at 4 . 2 m ( 71 MHz ) and producing about 5 kW . This was completed on a crash basis , and in early September 1941 , the set detected a bomber at a range of 97 km ( 61 mi ) . The system , Japan ’ s first full radar , was designated Mark 1 Model 1 and quickly went into production . RRF . In parallel with the VHF work , Yoji Ito also returned to the magnetron applications , resulting in Japan ’ s first pulse - modulated microwave RRF set . It operated at 10 cm ( 3 GHz ) and produced a peak - power of 2 . 0 kW . A prototype was tested in October 1941 , and several versions for surface ships and submarines were soon put into production . Naval officials favored the microwave sets because with very narrow beams they were less vulnerable to interception . Pearl Harbor . On December 7 , 1941 , Japan initiated an attack on Pearl Harbor , entering World War II . Yoji Ito was made a department head at the NTRI and was promoted to Captain . In the war years , he was responsible for many developments in VHF RRF systems , but was most proud of his microwave equipment . He personally led the development of Japan ’ s first airborne microwave RRF system . This was a 25 - cm ( 1 . 2 - GHz ) set producing 2 kW and weighing about 70 kg ( 150 lb ) . It was designed for the " Gekko " night - fighter . He was also involved the Japan ’ s countermeasure s equipment , particularly receivers to warn when vessels or aircraft were being observed by American radars . Return to magnetrons . Development at the NTRI continued on magnetrons , resulting in higher and higher power . 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 . ” In 1943 , work began in highest secrecy on a " Ku - go " ( Death Ray ) device . Laboratory . A special laboratory was set up near Shimada , in the Shizuoka Prefecture , for developing a high - power magnetron that , if not as powerful as Tesla had boasted , might at least incapacitate an aircraft . A number of Japan ’ s leading physicists were involved . A 20 cm magnetron producing 100 kW was achieved , and by the end of the war a 1000 kW ( 1 MW ) unit was undergoing preliminary testing . At that time , the development was terminated and the hardware as well as all documentation was destroyed . Disbanding of the Japanese military . With the surrender of Japan on August 15 , 1945 , all organizations , facilities , and projects related to the military in Japan were disbanded . Scientists and engineers , as well as military technical officers , engaged in communications and radar formed the base for Japan ' s future electronics industry . Captain Yoji Ito was among this large group of individuals . Koden . 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 . Unfortunately , Ito died in 1955 , but the firm continues as a worldwide supplier of marine electronic equipment .