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Various connecting cables in the electric multiple unit (EMU) are one of main radiation sources in the whole vehicle EMC test. So it is of great significance to research the factors affecting the electromagnetic radiation of cables. A comparative test in the lab was designed. The magnetic and electric field emission data was gathered when the shielding layer of the shielded cable was stripped off or not. Through these tests, some valuable conclusions were obtained. Then some suggestions on cable maintenance and construction were put forward.

The radiation emission of rail transit vehicles in operation is usually affected by environmental factors such as weather. In this paper, the radiation emission of the vehicle is tested under sunny and rainy environmental conditions, and the impact of the vehicle's radiation emission under the rainy environment is obtained by comparison. This not only helps to avoid some unfavorable factors in the test process, but also has certain reference significance for the electromagnetic protection of rail transit vehicles.

Based on Surface Acoustic Wave Resonator (SAWR), the SAWR equivalent circuit is built, and its model is established, so the circuit parameters of SAWR are obtained by S11 of Vector Network Analyzer (VNA). Furthermore, taking the T type for example, the values of interface matching element are calculated based on self-adaptation matching theory. The processes of actual matching verify the validity of theoretical matching research, and finding the matching difference between the actual value and the calculation value. Then single ended interface module is designed, tested, wired and wireless analyzed, sensor analysis, the results of which show the validity of single ended interface module and give a scheme of Pi-CLC double ended interface module based on linearity and sensitivity. Finally, double ended interface module is also packaged, wired and wireless test proves the validity of it, the difference frequency analysis shows that reference resonator not affect the main resonator to dominant the difference frequency changing with capacitance sensor and SWR analysis shows the design validity of low mismatching network.

A sensor antenna which is suitable for using as SAW passive wireless temperature measuring system has been designed based on the basic theory of the helical antenna in this paper. The size of the helical antenna has been identified. Firstly the modeling and optimization of the helical antenna have been carried out by using the HFSS software, thus the final dimension of the helical antenna with 433MHz resonant frequency and 300∼500 MHz broadband has been determined. Then a impendence matching network between the antenna and the sensor has been designed by using the ADS software, which makes their input impendence conjugate. The simulation results are in good agreement with the measured ones. The voltage standing wave ratio (VSWR) of the antenna is less than 1.2 over the whole frequency range. Finally the sensor is wireless tested combining with the reader, showing the practicability of the sensor.

Viscosity is one of the characteristic parameters of liquid. The measurement of liquid viscosity is required in many applications. Compared with other acoustic wave device, the shear-horizontal acoustic plate mode wave (SH-APM) device is suitable for liquid sensing. In this paper, the theoretical model of SH-APM device loaded with viscous liquid is built using the propagation characteristics of acoustic wave in laminated mediums, the liquid viscosity is introduced by adding the imaginary part in liquid elastic tensor, and the condition of exciting SH-APM in the piezoelectric plate by inter-digital transducers is researched. Choosing PZT-5H piezoelectric ceramic as substrate material, the numerical calculation is implemented and the SH-APM device is fabricated accordingly. Using different ratios of pure water and glycerol as liquid samples, the validity of liquid viscosity sensing by SH-APM is proved by the experimental results.

Love wave device is one of the typical SAW(surface acoustic wave) devices. Relative to other acoustic sensors, the Love wave liquid sensor has some obvious advantages. In this paper, the theory model of Love wave is established, the influences of liquid viscosity on propagation velocity and attenuation of Love wave are numerically analyzed. The changes of Love wave sensitivity to liquid viscosity and density with the ratio of the film thickness to the acoustic wavelength are numerically analyzed.

Acoustic Plate Mode Wave (APM) device is suitable for liquid-phase measurement. The appearance of liquid loading would lead to the energy leakage of APM and the reasons are various. According to acoustic wave propagation theory in the layered medium, this paper establishes the APM analysis model with liquid loading. Using non-viscous liquid, conductive liquid and viscous liquid as examples, by numerical simulations of general APM, sagittal APM and shear-horizontal APM, the APM energy leakage with liquid loading is researched, and the reasons are concluded. Furthermore, the two-dimensional analysis model of leaky APM is established by adding attenuation factor in the expressions of acoustic field components. The leaky APM propagation velocity and attenuation factor are obtained by the method of “surface effective permittivity rough-searching” added by “boundary conditions coefficient determinant refined-searching. The APM devices are designed and tested. The experimental results are in agreement with the numerical simulations.