Measurement System Of Transmission Attenuation Power Ratio For Electromagnetic Noise Suppression Sheets

In recent years, it's the tendency to design the electronic products into high-frequency, integration, microminiaturization and functionalization, which will be convenient to our life greatly, due to their portability and multifunction. However, a serious problems of electromagnetic interference(EMI) will harm human's health, because a large number of high frequency devices are integrated into a small room. Then, electromagnetic noise suppression sheet(NSS), as a kind of effective composite material could weaken the influence of EMI, has attracted the wide attention of institutes and manufacturers for its extensive application and excellent suppression effect on electromagnetic noise. Therefore, it's of great significance to investigate the properties of the electromagnetic noise suppression sheet.In this paper, we analyze the methods for measuring the performance of the NSS provided by the IEC 62333-2 standard files firstly, which is promulgated by the International Electrotechnical Commission. And our research is focused on measurement method for the transmission power loss ratio, according to the practical applications. Secondly, through analyzing the S parameter in dual port network model, the relationship between the S parameter and the parameters to be tested is built. Based on the microstrip line test board and combined with the Virtual Instrument technology, the software and hardware platform of the automatic measurement system for transmission power loss ratio are established. Consulting the details of materials and the size from the international standard, we build a microstrip line measurement instrument through the printed-circuit board technology on the double-side copper-clad boards and assemble the active devices and other components.The graphical programming software Lab VIEW is used to design the program, and the HP8720 B vector network analyzer is controlled via the VISA interface to complete the data collection, analyzing, saving and other functions. The whole software system adopts the modularization design and realizes the functions, such as the display of measurement data, equipment configuration, automatic measurement, data analyzing and excel files generating and so on. At last, we analyze and discuss the source of the error and the calibration method, and verify the availability of the measurement system by comparing the actual measurement results.The experimental data shows that the measurement results meet the international standard within 0 ~ 6 GHz, which proves that the designed and built measurement system for transmission power loss ratio of elecmagnetic NSS is effective and stable.