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Yoshihisa Okumura was born at Isikawa Prefecture, Japan in 1926.
He entered Kanazawa Institute of Technology in 1944, specialized in electrical engineering. He graduated the Institute in 1947. He got the job at the Electrical Communication Laboratory of PTT in 1950, and main research project was the survey of radio propagation characteristics. Okumura´s contribution to cellular system in 800MHz band would be started from then.
(1) In order to realize the economical commercial mobile system, it will be essential to understand the complete characteristics of radio propagation phenomena which will differ from the various circumstances of radio path.
Okumura executed the above-mentioned characteristics using testing cars. His study was included various situations such as in metropolitan area, suburban area, and even mountainous area. His measurements had covered wide range of frequencies from VHF to UHF band; 450,900,1310,1430 and 1920MHz for distances of 1 to 100km. Also, he changed the height of receiving/transmitting antennas, from grand level to several 10 meters, having various gain characteristics. His work was lasted for about 10 years.
Finally his work was published in the ELECTRICAL COMMUNICATION LABOLATORY VOL 16, NUMBER 9-10, 1968. During his work, the Japanese delegate to the CCIR (International Radio Consultative Conference) in ITU conference submitted the achievement of Okumura on radio propagation to CCIR. The CCIR was recognized that the contribution might be used effectively by engineers of every member countries and adapted it as a CCIR Recommendation. The curves shown in the document have been called ”the Okumura Curves”, and been used not only in academic study but also practical work in construction of various radio systems in the world. It will be obvious how his work was valuable in wireless academic and/or industrial field. After finishing the above mentioned fruitful work, he was promoted to the director of mobile system research section of ECL (The Electrical Communication Laboratory) in 1970.
(2) Okumura´ directorship of mobile system research section
First, he and his staffs made elaborate research project for developing of the high capacity land mobile system and proposed to the director of ECL. The proposal was approved and they acquired the budget. Next, for his 20 researchers he divided into several sub-project teams to enact the research work most effectively. He was appointed to a member of the Radio Advisory Committee, one of the consultative organizations for the Minister of PTT. As a member of the Radio Advisory Committee, he made great effort to explain his former propagation result to other members which would be applicable to construct cellular system using 800MHz frequency band. Finally they agreed his proposal. Also he submitted the technical paper entitled” The system object for the large capacity land mobile system” in October 1971(CS-71-77), which was welcome from many radio manufacturing enterprises in Japan.
He retired the ECL of NTT in 1975 and took a job in TOSHIBA Co. In 1979 he became the Professor in Kanazawa Institute of Technology. He retired from the Institute in 2000 and is now at the Emeritus at Kanazawa Institute of Technology, Ishikawa, Japan.