Active Magnetic Shielding Using Symmetric Magnetic Field Sensor Method

Active magnetic shielding is a cheap and effective method for shielding magnetic noise that allows shielding the very low frequencies. In active magnetic shielding, it is possible to shield magnetic field sensor positions. However, there is a problem in which the shielding factor decreases at other positions. Also, the problem of cross-axial interference occurs when the magnetic field sensor cannot be installed at the center of the compensation coils, since the measurement object is installed at the center. In this study, an arrangement of the magnetic field sensors which solves these problems is proposed. This method installs pairs of magnetic field sensors symmetrically offset from the center along each axis. An experimental demonstration was carried out in a small model in order to prove the effectiveness of the proposed method. Our results show that a high shielding factor is obtained, even if the magnetic field sensor is not installed at the center.