Japan’s only shortwave station still in business after 80 years

By MORIKAZU KOGEN/ Staff Writer
June 24, 2021 at 07:10 JST

A forest of steel towers at KDDI Corp.’s Yamata Transmitting Station seen from atop the main building in Koga, Ibaraki Prefecture, on April 26. The highest tower stands 70 meters. (Morikazu Kogen)

KOGA, Ibaraki Prefecture – Standing tall and proud over an area of 1 million square meters or so, a forest of steel towers in two-tone red and white is the dominant feature under the blue sky against the backdrop of Mount Tsukubasan.

The main building almost looks the same as it did when it was built 80 years ago, although some parts have been extended and renovated. (Morikazu Kogen)

This is KDDI Corp.’s Yamata Transmitting Station, the nation’s only facility broadcasting shortwave radio programs to overseas listeners.

The station started broadcasts on Jan. 1, 1941. The main building still retains a prewar ambience.

Shortwave radios were the primary means for people across the world to receive audio content from Japan without a large-scale facility before satellites and submarine cables came into existence.

The 1945 announcement of Japan’s surrender by Emperor Hirohito was transmitted from here to military personnel on overseas battlefronts.

A photo apparently taken either during or after the war shows the main building of the Yamata Transmitting Station. (Provided by KDDI Corp.)

When it was completed in 1940, Yamata, now part of Koga, was a typical farming village with a population of 4,536, of whom 90 percent were farmers, according to a 1941 local history pamphlet.

“A large area of flatland was available, and it was less prone to damage from snow and typhoons,” said Kazuhiro Matsui, 50, a senior official in charge of infrastructure, who served as a guide when the station was shown to media representatives in April. “I think it was the only place fit for the station in the country.”

The steel towers are arranged in such a way that 18 transmission antennas cover 360 degrees to send broadcasts as far north as Boston and London and as far west as Seoul and Nairobi.

Vacuum tubes installed in the transmitters are replaced once every two years or so. (Morikazu Kogen)

The seven transmitters are installed with vacuum tubes, which have been used to amplify radio waves since the station started operations. Each tube weighs about 70 kilograms, according to Matsui.

The control room monitors the transmitters and other broadcasting facilities around the clock, and workers switch from one antenna to another at each broadcast time to ensure the facilities are working properly.

FM waves, which are higher in frequency than shortwaves, penetrate the ionosphere and can only travel up to around 100 km. AM waves, which have a lower frequency, are attenuated when they are refracted from the ionosphere or the Earth’s surface, resulting in shorter travel distances than shortwaves.

Shortwaves refer to a range of radio signals from 3 to 30 MHz. The signals reach far corners of the globe because they bounce back and forth between the Earth’s surface and the ionosphere that envelopes the planet at a height of several hundred kilometers.

Workers constantly monitor radio signals in the control room, switching transmission antennas depending on broadcasting programs. (Morikazu Kogen)

Shortwave radio broadcasting was particularly valued during wartime.

Japan’s propaganda broadcasts to its colonies, as well as “The Zero Hour,” an English-language radio program aimed at demoralizing U.S. troops in the South Pacific, were broadcast from here.

A photo apparently taken during wartime shows female workers inside the Yamata Transmitting Station. (Provided by KDDI Corp.)

According to Matsui and other sources, women were mobilized from surrounding areas and put in charge of radio transmission, maintenance and other services because engineers at the station were pressed into military service to work as communications officers.

“I heard that those who worked at the station during the war came back to see cherry blossoms for old times’ sake,” Matsui said.

Despite the advent of satellite and internet broadcasting, shortwave radios still have an important role to play.

The Yamata Transmitting Station is broadcasting NHK’s World Radio Japan program.

Shortwave radios served as a source of information during the Persian Gulf War in 1990 for Japanese people stranded in the Middle East.

In 2007, the Investigation Commission on Missing Persons, a group investigating North Korea’s abduction issue, started broadcasting the Shiokaze shortwave radio program directed at North Korea from the Yamata Transmitting Station.

“Shortwaves can reach any location under any circumstances, and you don’t need extensive equipment to receive them,” Matsui said. “Their importance remains unchanged.”

© June 24, 2021

This material remains © The Asahi Shimbun Company and is only to be used for non-commercial personal or research use. Any other use requires permission of the copyright holder.

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