Ocean Ultra/Extremely Low-Frequency Magnetic Field Detection System Based on Highly Sensitive Magnetoelectric Sensors

Magnetoelectric magnetic sensors (MESs) magnetic sensors (MSs) have attracted much attention because of their high sensitivity, low noise, and power consumption. They have been gradually studied in the field of magnetic field detection of marine targets. In this article, we proposed a novel ocean bottom magnetic (OBM) receiver based on our highly sensitive ME MES. The sensitivity of such sensors is higher than 18 V/Oe from 0.2 to 10.0 Hz, which is better than the current international leading Mag-13 fluxgate sensor. Its equivalent magnetic noise is close to 7 pT/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\surd $ </tex-math></inline-formula>Hz at 1 Hz. Using two single-axis MESs to form a set of horizontal orthogonal measured modes, the OBM receiver can detect the ship’s ultra/extremely low-frequency (ULF/ELF) vector magnetic signals. Furthermore, the performance of such a system has been demonstrated by performing a marine experiment using an artificial source (electric dipole source) that can generate standard ULF/ELF signals. The results show that the measured data of the OBM receiver are in good agreement with the simulated data, and the maximum error at the extreme value is less than 20%. This work will provide critical technical support for MESs in marine target detection and has excellent potential application prospects.