Comparison between Shielding Characteristic and Radiated Emission in Shielded Two-Wire Cables

Radiated emissions from in-vehicle equipment are determined by the source, such as switching device, wire harness, and connector. This paper discusses how wire harnesses affect radiated emissions. Specifically, the shielding characteristics of shielded wire harnesses were evaluated using the triple coaxial method specified in the IEC 62153-4 series. The characteristics were evaluated not only in common mode but also in differential mode. The leakage from the shield is higher in common mode, as is generally known. However, the difference between them is only a few dB, depending on the type of cable. In addition, the radiated emissions from the wire harness were measured. The measurements were performed by modifying the CISPR 25 measurement system to facilitate comparison with the shield characteristics. The evaluation of the differences between the two types of shielded cables showed that the shield characteristics and radiated emissions were strongly correlated.