Low noise, high

stability orthogonal fluxgate sensor for


Janosek, M. (1), Butta,


(1) Dept. of

Measurement, Czech Tech. Univ. in Prague


We present a 1pT/sqrtHz @ 1 Hz orthogonal

fluxgate sensor working on the first harmonics, with the white noise

level of 0.3 pT, suitable for variometers.


The low noise is a combination of material selection, processing and

encapsulation - we present how the ultra-low frequency noise (mHz

range) largely depends on the sensor encapsulation. The sensor is

manufactured of ~100um diameter amorphous core and is ~6cm long,

allowing for replacing the common sensors occuring in state-of-the-art

variometers. The high geometric directivity is also a benefit from the

point of further variometer calibrations.


For sucesfully using the fluxgate sensor in a variometer, the key

point in the electronic development was understaning and supressing

the offseet drift of the sensor. We show schemes which sucessfully

suppress the sensor temperature drift by alternating excitation.