Influence of Power Line Termination Device Placed on Ground Plane to NSA Measurement

To improve the reproducibility of radiated emission measurement, a very high frequency line impedance stabilization network (VHF-LISN) has been proposed and has been under consideration for standardization into basic measurement standards (CISPR 16-2-3 and CISPR 16-1-4). Since a VHF-LISN can be placed on the ground plane (GP), we thought it was necessary to investigate the effects of placing it. Initially, the effects were investigated by normalized site attenuation (NSA) measurements. The influence of a common-mode absorbing device (CMAD) and an artificial mains network (AMN) were also investigated in the same way for comparison. Then, we created simulation models of antennas and these devices. Both actual measurement results and simulation results demonstrated that the influence of VHF-LISN was smaller than the influence of CMAD or AMN. The results suggest that evaluation of the influence on the NSA of a VHF-LISN placed on the GP is not needed if the evaluation is not required for a CMAD or an AMN.