Specification of Alternative Test Sites With Respect to Given EMC Field Standards

During the last years a lot of new test facilities have been presented which claim to be in accordance with standard test procedures. The intention of this paper is to show a way to relate the standardized procedures to the new alternative methods. As an example the most referenced standard for field immunity measurement the IEC 1000-4-3 is used. At first the main goals for insuring reproducible field conditions are extracted from this standard and are discussed in this paper. For the main goal "field homogeneity" a modified procedure is presented. The field strength can be calculated as a deterministic value. In this paper deviations of the field strength from a mean are considered as statistical errors. This leads to a more general definition of the field uniformity. Two configurations of test sites requested by IEC 1000-4-3 are studied with this statistical but more general approach. The paper stresses the point of field uniformity and the problems of its definition. A recommendation for a novel and more versatile definition is given. Finally some hints on error limits considering polarisation of the field vector and far field condition are given.