New magnetic field system enables wireless data transmission hundreds of feet underground

South Korea's ETRI demonstrated wireless data transmission 100 meters underground using low-frequency magnetic fields.

The test used a roughly 1-meter loop transmitter, a compact magnetic-field sensor, and QPSK modulation at 2 kbps.

The experiment was conducted in limestone bedrock and builds on earlier 2023 tests and ~40-meter links.

ETRI says the method could apply to rescue, underground facilities, offshore drilling, and defense where radio signals fail.