Characterisation of magnetic wires for fluxgate cores

Orthogonal fluxgate sensors need only a single core and they can be made very small. We show how to measure properties of composite Cu/Py ferromagnetic wires to be used as cores for these sensors. Besides the well known axial loops we show how to measure the circumferential hysteresis loop and gating curves, which can directly be used for sensor modeling. It is generally believed that in composite wires the majority of the current flows through the copper core, thus reducing the possible perming effect of poorly magnetized core sections. We will show that this is true only at very low frequencies and for low magnetic layer thickness. The calculated values can be used as a starting point for FEM simulations. (c) 2007 Elsevier B.V All rights reserved.