A high performance orthogonal fluxgate magnetometer based on the fundamental mode of operation

One can build an offset-free orthogonal fluxgate (OFG) by introducing periodical bias flipping into its fundamental mode. However, bias clipping incurs flux reversal in the wire core, hence, voltage spicks to the sensing coil that prevent from the use of a high-gain preamplifier and also cause magnetic noises in the output. In this paper, further developments is made to suppress voltage spicks and to push the resolution better than 0.1 ηTΛ/Hz. A prototype fluxgate magnetometer is built using a Co-based amorphous magnetic wire bent into a U-shape with straight sections as long as about 3 cm and a 250-turn winding on each section. Voltage spicks are reduced by a factor of 1/3.