Transverse field effect in fluxgate sensors

A model of a fluxgate magnetometer based on the field interactions in the fluxgate core has been derived. The non-linearity of the ringcore sensors due to large uncompensated fields transverse to the measuring axis are calculated and compared with measurements. Measurements of the non-linearity are made with a spectrum analyzer measuring the higher harmonics of an applied sinusoidal field. For a sensor with a permalloy ringcore of 1 in. in diameter the deviation from linearity is measured to about 15 nT(p-p) in the earth's held and the measurements are shown to fit well the calculations. Further, the measurements and the calculations are also compared with a calibration model of the fluxgate sensor onboard the 'MAGSAT' satellite. The later has a deviation from linearity of about 50 nT(p-p) but shows basically the same form of non-linearity as the measurements. (C) 1997 Elsevier Science S.A.