A massive antenna in China can use Earth itself to send signals to submarines thousands of miles away

The biggest antenna on the planet is up and running in central China, opening up long-distance communications with submarines as well as civilian applications, according to engineers and scientists involved in the project.

The exact location of the facility has not been revealed but is believed to be somewhere in the Dabie Mountains, a protected natural reserve straddling Hubei, Anhui and Henan provinces.

From space, the antenna, which is formed by a network of cables and pylons much like those in ordinary power lines, would look like a giant cross more than 100 km (62 miles) long and wide.

But at the ends of those lines, copper nodes are fixed deeply into thick granite. Two powerful underground transmitters — capable of working independently in case one is damaged — charge one megawatt of electrical current and turn the Earth into a giant radio station.

According to a paper published in last month’s Chinese Journal of Ship Research, receiving devices planted 200 metres (700 feet) below the surface on the sea floor can effortlessly pick up signals from the giant antenna 1,300 km (800 miles) away – a range that covers the Korean peninsula, Japan, Taiwan and the South China Sea.

The project’s lead engineer Zha Ming and his colleagues, from the Wuhan Maritime Communication Research Institute, said the facility was designed to maintain underwater communications over a total range of 3,000 km (1,900 miles) — enough to reach Guam, the biggest US military base in the western Pacific Ocean.

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