to detect aircraft. For consultation, they turned to Professor Yagi who suggested that this might be done by examining the Doppler frequency-shift in a reflected signal. Funding was provided to the Osaka Laboratory for experimental investigation of this technique; Kinjiro Okabe was assigned to lead the effort. His theoretical analysis indicated that the reflections would be greater if the wavelength was approximately the same as the size of aircraft structures. Okabe developed an experimental apparatus using a VHF transmitter and receiver with Yagi-Uda antennas separated some distance. In 1936, he successfully detected a passing aircraft by the Doppler-interference method; this was the first recorded demonstration in Japan of aircraft detection by radio. With this success, Okabe's research interest switched from magnetrons to VHF equipment for target detection. The funding for Okabe's target detection project was not continued; the top levels of the Imperial Navy believed that any advantage of using radio for this purpose were greatly outweighed by enemy intercept and disclosure of the sender's presence. Okabe continued to devote much of his research to improving magnetrons. Although this technology was picked up by other organizations, including the Naval Technology Research Institute where Yoji Ito led in further improvements and the eventual incorporation in detection system for the Japanese military, Okabe continued to publish in the open literature. During and following the war years, Okabe remained very active at the Osaka Laboratory. While Okabe's initial proposal for radio detection was not accepted by the military, time would see this position greatly change. The 1944 Order of Culture award for significant advancements in science and technology was presented to Okabe by the Emperor of Japan in recognition of his early efforts. Medical applications In 1955, his interest turned to medical applications of ultrasound, and he suggested to Shigeo Satomura, one of his graduate students, that he apply Doppler ultrasound techniques to medical diagnosis. This research was very productive, and led to new applications of this technology providing non-invasive localised imaging. References 1896 births 1984 deaths Japanese electrical engineers Japanese scientists Tohoku University alumni Laureates of the Imperial Prize