China has built a massive radio antenna spanning an area five times the size of New York City.
The controversial Wireless Electro-magnetic Method (WEM) project took 13 years of construction, reports the South China Morning Post.
Built on 3700 kms of land, it is designed to emit extremely low frequency radio waves, or ELF waves.
While Chinese officials maintain it will be used for earthquake alerts and mineral detection, the project could be used in key military signals.
Experts say submarines hundreds of metres below the ocean can pick up the radio waves without having to resurface and expose themselves to surface vessels.The massive radio antenna may would enable Chinese submarines to communicate with their bases while submerged. (AP)
Both the US and Russia have built similar radio antennas to develop communications with submerged submarines – but not on this scale.
Project WEM has been cloaked in secrecy and its precise location is unknown. But information gleaned from Chinese journals suggest it is in the Huazhong region in central China – home to 230 million people.
Its principal surface structure is a pair of high voltage power lines from north to south, east to west. They form a cross that stretches 60 kms wide and about 100 kms long.
Two power generators electrify the ground, emitting electromagnetic radiation in the ground beneath.
As well as passing through the atmosphere, the radio pulses travel through the Earth’s crust, with a range of up to 3500 kms.
A receiver within that distance would be able to detect those signals.
But the potential effects of electromagnetic radiation on local residents have triggered concern among experts.
Previously the the International Agency for Research on Cancer has warned that ELF waves are “possibly carcinogenic to humans”.
In a report regularly updated from 2007, the World Health Organisation recorded many academic studies linking ELF radiation to illnesses such as depression, sleep deprivation, breast and brain tumours and suicide.
By Richard Wood