Impact of different cable types and positions on CISPR 15 radiated disturbance measurement

This paper deals with an empirical evaluation of variables that may impact radiated emission measurement – mainly for CISPR 15 lamp tests. Edition 9 of CISPR 15 brought modifications that improve reproducibility, the most notable of which are the obligation of using a coupling/decoupling network (CDN) and the reference to the CISPR 16-2-3. The practical tests in this study showed that both the use of CDN and the use of one single cable placement have an impact of up to 74% and 59%, respectively, on the results. Other possible improvements were evaluated. The use of a pre-amplifier and the turntable rotation speed had no impact at all as long as CISPR 16-2-3:2016 setup is used. Tests with cables of different section areas, even when applying the same positioning pattern, resulted in relevant differences (up to 7.26 dB and 6.92 dB at 34 MHz and 200 MHz, respectively). Further studies are currently underway to clarify how the cable acts like an antenna and how to properly consider it in future CISPR 15 versions. The results indicate that, for better reproducibility, CISPR 15 edition 9 must be adopted instead of older editions, although improvements can still be achieved by considering the impact of different cables.