▲ ETRI researchers who developed the world's first 100m underground magnetic field communication technology (from left: Dr. Jang-Yeol Kim, Dr. Hyun-Jun Lee, and Dr. In-Gwi Cho)

Low-frequency magnetic fields open up possibilities for underground disaster and military operations communications

The Electronics and Telecommunications Research Institute (ETRI) has succeeded in developing the world's first magnetic field-based wireless communication technology capable of transmitting and receiving voice signals over a distance of 100 meters underground. This demonstrates that stable communication is possible even in underground environments where conventional wireless communication cannot reach, and it is expected to be utilized in various fields in the future, such as mine accident rescue, management of buried facilities, and military operations.

ETRI recently announced that it has achieved voice communication at a data speed of 2–4 kbps by utilizing a 1-meter diameter transmitting antenna, a receiving sensor of several centimeters, and a low frequency of approximately 15 kHz. In particular, by successfully testing bidirectional communication between the surface and a 100-meter underground section in a mine with the extreme environment of limestone bedrock, it achieved a result that surpasses existing overseas research, which had been limited to the level of tens of meters.

This technology was developed based on the characteristic of magnetic fields stably passing through underground media. While conventional RF-based wireless communication was limited underground due to signal attenuation, magnetic field communication is attracting attention as a new wireless channel by overcoming structural constraints.

ETRI published the technology in the international academic journal IEEE IoT Journal and has filed domestic and international patents for key components such as transceivers, low-frequency modems, and bandwidth expansion technology. To date, 12 SCI papers, 8 international patents, and technology transfers have been completed.

Principal Researcher Jo In-gui stated, "Since we successfully established communication underground where even household radios cannot reach, we can significantly reduce the possibility of communication disruptions during rescue operations." Park Seung-geun, Head of the Radio Research Division, emphasized, "As a highly reliable communication tool required for extreme environments such as tunnels, offshore drilling, and national defense, it will contribute to the entire industry."

This research was conducted with support from the Ministry of Science and ICT and the Institute of Information and Communication Technology Planning and Evaluation (IITP), and was developed and demonstrated in cooperation with private companies Edmotec Co., Ltd. and Doit Co., Ltd.