Design And Analysis Of Magnetic Field Sensors Based On Surface Acoustic Wave Technology

Magnetic field sensors are playing a very important role in human production and life.With more special passive and high temperature application scenarios,the old magnetic field sensors could not meet people's needs.There are demands for new magnetic field sensor design and research work.Sensors based on surface acoustic wave(SAW)technology have advantages of anti-interference,wireless,passive.Therefore,the design work of the magnetic field sensor based on SAW technology has been carried out.In order to design the SAW-based magnetic field sensor,the surface acoustic wave,magnetoimpedance and magnetostrictive techniques were studied respectively.The SAW technique is used to study the mechanism and manufacturing process of SAW,especially the SAW transducer used in this project.The giant magnetoimpedance part focuses on the giant magnetoimpedance characteristics of amorphous wire and analyzing theoretically.The magnetostrictive properties of Tb-Dy-Fe were studied by means of the theoretical analysis and the testing platform.Based on above researches,two kinds of magnetic field sensors based on SAW,magnetoimpedance and magnetostrictive technology are designed: the giant magneto-impedance SAW magnetic field sensor and the magnetostrictive SAW magnetic field sensor.According to the most basic principle in the design process,similar research contents and achievements of other researchers are absorbed,and the corresponding magnetically sensitive material units are optimized.In order to test the design effect of the magnetic field sensor,the experimental test platform was built and the magnetic field sensor experiment was carried out.The parameters of the magnetic field sensor are obtained by testing the scattering parameters of the SAW chip using a vector network analyzer.In this thesis,two kinds of SAW-based magnetic field sensors are designed and synthesized,which make full use of SAW devices characteristics of passive and the sensitivities of the amorphous wire and Tb-Dy-Fe alloy for magnetic field changes.The giant magnetoimpedance SAW magnetic field sensor measurements show that if the magnetic field range is from 0 to 2.0 Oe,the enter reflection coefficient will increase linearly,which can achieve one-dimension and two-dimension low-intensity magnetic field detection.The magnetostrictive SAW magnetic field sensor measurements show that the sensor can be used for two-dimension high-intensity magnetic field detection.Compared with the existing SAW magnetic field sensors,two sensors designed and tested in this thesis have similar performance but higher operating frequency?smaller size.