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OKI and the Changing Times

Part 7: Dominating world markets with OKI's millimeter-wave technologies

OKI's business expanded alongside the nation's rapid economic growth. The company transformed itself from a telecommunications equipment manufacturer into a general manufacturer offering a wide range of products, including electronics. One milestone along this path was the development of millimeter-wave telecommunications technologies.

Successful development of a millimeter-wave magnetron

In 1955, Tokyo Telecommunications Industries (now Sony) released a revolutionary transistor which swept the world. At the time, one Japanese company after another was venturing into the world of electronics to build devices that controlled the flow of electrons. Led by then President Suteji Kanbe, OKI committed itself to research and development in this area. One challenge was millimeter-wave technology (involving wavelengths of 1-10 mm and frequencies of 30-300 GHz).

At that time, microwave technology (with wavelengths of 1 m or less and frequencies of 1-100 GHz) flourished. Shorter wavelengths allow greater transmission multiplexing, which in turn allows the transmission of more information. Other research centers and manufacturers were competing in research on wavelength shortening technologies. Ahead of all these companies, OKI delivered a revolutionary product, a millimeter-wave magnetron, which it had been developing with Osaka City University since the spring of 1955. A magnetron is one type of oscillation vacuum tube. With their ability to produce powerful microwaves, magnetrons are still used in broadcasting, telecommunications and radar equipment, and microwave ovens, among other applications.

In December 1955, OKI, ahead of any other company in Japan, succeeded in developing a magnetron capable of generating millimeter waves 7 mm in wavelength. The product attracted great admiration. According to the Telecommunication Research Center of the Nippon Telegraph and Telephone Public Corporation, it marked "the first step in transforming the telecommunications industry." The device would "advance research into physical structures and atomic physics," an academic society proclaimed.

Leading the world with OKI's millimeter-wave technologies

Millimeter-wave klystron

However, the millimeter magnetron only produced millimeter waves intermittently. It was not suited to transmission applications. Rather than resting on its achievements, OKI began developing a "klystron electron tube" that would generate continuous millimeter waves. Three years later, in 1958, OKI became the first Japanese company to develop such a device.

OKI's success in making millimeter waves suitable for transmission had significant impact worldwide. OKI received a rush of inquiries and orders from world-leading companies, institutions, and prestigious universities, including Bell Labs, RCA, Hughes, NASA, COMSAT, Lockheed, and Douglas. In 1962, the product was incorporated into ground stations for the Telstar communications satellite launched by NASA. This encouraged many other satellite ground stations to adopt the product, expanding OKI's reputation overseas.

Making another leap forward, OKI constructed a production facility for exclusive production of millimeter-wave electron tubes at its Hachioji Plant in April 1961, at the time the world's only facility of its kind. OKI developed approximately 60 types of millimeter-wave electron tubes, which won wide renown for their high power, high stability, and long life and helped establish OKI's world reputation as the leading supplier of millimeter-wave technologies.

Integrating millimeter-wave and radar technologies

Following the Second World War, OKI vigorously pursued technical collaborations with overseas companies to introduce various state-of-the-art technologies. One such collaboration for radar technologies was established in 1954 with Raytheon Company of the U.S. This alliance produced a radar rain gauge. Coupled with this radar technology, OKI's millimeter-wave technologies opened up new markets.

Before this technology was invented, rainfall had been measured with funnel-type gauges or other such devices designed to collect rain at certain geographical points. The new technology computed rainfall using radar reflections, instantly determining total precipitation across wide areas. Inspiration for this technology came from papers published by an American meteorological society. Learning of the many studies underway on the reflection of radio waves from raindrops, OKI extended its own studies and discovered a correlation between the amount of rainfall and radio wave reflections.

This came from OKI's inventive insight. Having already produced an original, world-leading millimeter-wave magnetron, which would be necessary for the radar, OKI decided to launch systems development, based on its conviction that it could manufacture the necessary computation and display devices in-house. Named the CPM6, the radar rain gauge released in 1961 drew the interest of the National Center for Disaster Prevention, the Ministry of Construction, electric power companies, and others.

The first unit was delivered to the Kyushu Branch of the Rainmaking Research Association (part of the Science and Technology Agency) and was installed in Hitoyoshi City, Kumamoto Prefecture. Also used to evaluate rainmaking experiments, it paved the way to greater understanding and many new discoveries. The new radar rain gauge was also used by the National Center for Disaster Prevention in studies of ways to prevent flooding and by Tokyo Electric Power Company in surveys of precipitation in areas upstream of dams. The millimeter-wave technology to which OKI researchers devoted themselves, coupled with other electronics technologies, entered the phase of applications, finding their way into products that contributed to our lives.

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