Wide-angle magnetoimpedance field sensor based on two crossed amorphous ribbons

Soft magnetic amorphous ribbons have been exhaustively studied in order to use them as magnetic field sensitive elements based on the magnetoimpedance effect, MI. In comparison with other materials they exhibit some disadvantages like double-peak response for small values of the applied magnetic field due to the peculiarities of the surface anisotropy. In this work, magnetic properties, MI effect, and the angular dependence of the impedance on the applied magnetic field direction have been studied for CoFeMoSiB amorphous ribbon based sensitive elements in two configurations. The first one is a classic MI prototype with one amorphous ribbon sensitive element installed on a printed circuit board. In the second configuration two amorphous ribbons with the same size are placed in the board forming an angle of 15° between them. MI effect is measured in a frequency range from 0.4 to 10 MHz for exciting current amplitudes ranging from 2 to 20 mA. For this prototype of sensor device formed by two crossed amorphous ribbons, it is possible to obtain single-peak MI response and independent on the orientation of the external field output signal in a wide range of the angles from 0 to 45°, in contrast with the double peak and angle dependent response obtained for single ribbon sensitive element.