A shielded fluxgate sensor for spatially resolved measurements of magnetic dipole fields

The field and spatial resolution of fluxgate magnetometers in magnetic dipole fields were enhanced by incorporating a soft magnetic shielding layer surrounding the sensor. It is used to capture the stray fields from displaced dipole sources not being located directly under the sensor and reduces the coupling of their magnetic fields into the sensing fluxgate core. When dipole fields are the subject of the measurement, the shielding layer can also be used to capture homogeneous noise fields from the surrounding environment and to reduce their measurement signal. The field and spatial resolution of shielded sensors were measured in magnetic dipole fields. The impact of the shielding on homogeneous fields was studied by the sensor's sensitivity. It was found that both the field and the spatial resolution in dipole fields can be improved whereas the sensitivity to homogeneous (noise) fields will be reduced. The findings are supported by finite element simulations.