| The measurement of magnetic field has been used in many technology fields, such as industry, agriculture, national defence, biology, space navigation.With the rapid development of science and technology, more demands have been made of the magnetic measurement. In traditional magnetic field sensors, such as Hell sensor, flux gate sensor, vibrated and rotated coils, there were some flaws and disadvantage, for instance, too complicated circuits of the structure, high cost and limitation of using conditions. For the more researches of giant magnetioimpedance (GMI) effect, some new soft-magnetic materials, which exhibit better stability, higher sensitivity and speed respond, small size appears, provide good conditions for study of new sensors.In this thesis, we discuss theory of GMI effect in brief at first,then introduce that GMI effects of many materials in various forms, the relation between GMI effect and frequency of driving current, and some methods of improving GMI effect, moreover, we also review and summarize the kinds, capabilities, traits and using conditions of the sensors for magnetic field.In our work, the magnetic sensor consists of the probe and the processing circuit with microcontroller. For avoiding disturbance, we put the oscillation circuit, amorphous ribbon, per-amplifier and rectifier in the probe. The devices and apparatus of processing circuit, such as ATM89C52,A/DMC14433 and 4 bit LED, are low-cost and maturity in technology. In data processing, we use the least squares method to imitate, the fitting curve accords with voltage-magnetic field curve well, the fitting degree reach 99.99%. The measurement range of this magnetic field sensor is from 0Oe to 50Oe without difference in both longitudinal directions, the field resolution of sensor is up to around 0.01Oe, the maximum sensitivity of the probe of the magnetic sensor can reach 96mV/Oe. |
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