Fluxgate impedance analyzer for sensitivity and noise properties

The fluxgate sensor is known as a precision, low noise, reliable magnetic field sensor, and has been developed for decades. The sensor has been used in measurement systems, which need high precision in magnetic field measurements such as in satellite systems, navigation, and geological exploration. Although there are lots of competitors to the fluxgate such as Hall, GMR, and AMR sensors, the development of fluxgate sensors is still continuing to get better performance. There are still many potential developments of fluxgate sensors, to make it better than what is nowadays commercially available. The main big potential is the development of sensitivity and noise properties. Many efforts have been done to obtain this such as treatment of the core material, tuning the coils, making a new model of output voltage involving the core permeability or coil inductance, and the electronics signal processing optimization. The new model is intended to obtain the good permeability, inductance, or any other parameters for the best sensitivity and noise performance by designing the geometry. This thesis describes the development of a novel fluxgate analyzer for fluxgate sensor characterization, which is used for modeling the fluxgate sensor output to study the parameters that affect fluxgate sensor output. The characterization is based on the impedance of fluxgate sensor coils, which contain high permeability material as fluxgate sensor core. The non-linearity of the core permeability becomes the crucial and important topic in designing the impedance analyzer. The instrument has been designed to comply with the fluxgate sensor characteristics, which has low impedance and high core permeability. For that reason, the fluxgate analyzer has been designed with low output impedance and to be able to provide a very low current for fluxgate impedance measurement. A model from the impedance measurement is used to calculate and predict the fluxgate output sensitivity. Together with other physical parameters such as winding number and length, the model is utilized to set-up an equation to calculate the fluxgate output voltage and sensitivity.