Shielding Effectiveness Measurement of Twisted-Wire Pairs for Common-Mode and Differential-Mode Signals Using Absorbing Clamp Method

Twisted-wire pairs (TWPs) are a common signal transmission medium widely used to transmit the differential-mode (DM) signal. However, as the electromagnetic environment grows increasingly complex, there are more and more factors that can cause the common-mode (CM) noise. The CM noise can couple to TWPs, leading to an unwanted phenomenon known as mode conversion. In this study, data transmission is performed in the form of DM and CM signals, respectively. The DM signal is the normal signal transmission mode, while the CM signal simulates the worst conditions in which the mode-conversion effect is most pronounced. Based on a comparative analysis of experimental results, it is observed that there is a noticeable discrepancy in shielding effectiveness when confronted with different signal transmission modes. Therefore, the shielding effectiveness of TWPs becomes a critical factor in resisting the CM noise and maintaining signal integrity. It should be taken priority to improve the balance of TWPs and suppress the CM noise to ensure their reliable operation when surrounded by complex electromagnetic environments.