Three-Axis Fluxgate Magnetometer TFM1186
3-axis magnetometers
Advantages
+ High sensitivity
+ Measurements along one or multiple axes
+ Robust
+ Low power consumption
Constraints
– Unlimited range down to weak field strengths
– Relatively limited bandwidth
– Large sensor size
– Disturbs the measured field
Metrolab utilizes fluxgate sensors produced by a respected specialist to complement its Hall effect instruments, extending the range to very weak fields.
High Sensitivity for Weak Magnetic Fields
A fluxgate magnetometer consists of a soft iron core with two coils wound around it: a drive coil and a detection coil.
An alternating voltage continuously drives the core through a complete hysteresis cycle, from saturation in one direction to saturation in the other.
The detection coil measures variations in flux within the core.
An alternately saturated magnetic core produces a signal proportional to the surrounding magnetic field
The magnetic permeability of the core – the slope of the B vs H curve – is modulated as the core enters and exits saturation: when unsaturated, the core has the high permeability of soft iron, when saturated, it suddenly drops to the low permeability of vacuum.
This means that the flux density B within the core due to an external field H is also modulated; one can think of the flux due to the external field being cut off when the core saturates, and restored when the core desaturates – hence the name “fluxgate.”
Clever demodulation schemes enable the measurement of the amplitude of this field modulated by the detection coil.
