Miniaturised RPMMA‐Based Low‑Frequency Underground Positioning

ABSTRACT With the increasing development of underground spaces, position technologies for underground environments have attracted growing attention. Traditional methods based on high‐frequency electromagnetic waves are limited due to poor penetration. In contrast, the low‐frequency (LF) electromagnetic waves offer better penetration and robustness, but traditional LF antennas are huge. The rotating permanent magnet based mechanical antenna (RPMMA) can transmit LF signals while maintaining a compact and portable design. This paper investigates an underground positioning approach based on RPMMA. The spatial radiation characteristics of the antenna are analysed, and different position estimation models are proposed. Simulations are conducted to identify the optimal method, which is validated through experiments in a complex underground environment.