Subjects of discussion in radiated emission measurements above 1 GHz

摘要

Some emission and susceptibility EMC standards already require measurementsabove 1 GHz or test site validations (IEC 2006, CISPR 2006). A simpleassignment of the established measurement methods below 1 GHz to thefrequency range above 1 GHz bears some risks. The ratio between the physicalsize of the equipment under test (EUT) and the wave-length rises withfrequency. This increases the electrical size of the EUT. The directivitymay become larger and the radiation pattern of the EUT is getting morecomplex which reduces the probability to detect the maximum emission with asimple planar cut scan. To analyse these effects in more detail this papershows radiation characteristics of an exemplary EUT. The influence of areceiving antenna height scan and the angle increment of the turntable scanon the detection of the maximum of the electrical field strength will bediscussed. As a result some ideas will be given to reduce the measurementtime but keeping the reliability of the measurement results constant.