Research On Impedance-loaded Surface Acoustic Wave Sensor

The Prognostics and Health Management of the aircraft are of vital importance to the modern military.The various sensors installed in the aircraft structure are the core components of the technology.Because wireless passive sensor can effectively avoid the use of batteries,periodic replacement and maintenance,complicated layout design,it has been widely studied at home and abroad in recent years.Passive wireless Surface acoustic wave(SAW)sensor can be divided into two types.The first one is direct measurement of the SAW perturbations with the change of target detection,while the second one is the sensor which is composed of a SAW device and an external sensor.This paper studies the SAW sensor based on the latter,whose measurement of the target is realized through the change of the impedance of the external sensor.First,the basic theory and components of SAW sensor have been researched.The SAW device modeling and simulation method are analyzed.Then the coupling of mode(COM)is adopted to simulate the impedance-load SAW senser.The sensor uses double-channel structure,in which the test channel and the temperature compensation channel are independent,therefore the temperature can be decoupled.This paper introduces the fabrication process of SAW devices,and a impedance-load SAW sensor has been made for stress measurement.The simulation results and vector network analyzer measurement results are given,they are in good agreement.At last,the wireless passive sensor system is constructed for strain monitoring,the basic composition and working principle of the system is introduced,and the data processing of echo signal are analyzed in detail.the wireless transmission distance,stress sensing and temperature decoupling are measured.The paper selected phase as the benchmark of stress and temperature,established the relationship between phase,stress and temperature.By analyzing the data processing results,it can be concluded that the phase changes with stress obviously,the dual-channel is feasible for temperature compensation.