Test methods for electromagnetic shielding materials

Current methods and techniques for measuring the shielding effectiveness (SE) of composites intended for shielding electromagnetic interference in home and business computing devices are examined. Emphasis is placed on those techniques that offer the best repeatability of SE data and aid the original equipment manufacturer in their proper evaluation and interpretation. Experimental results show that the NBS flanged coaxial fixture method demonstrated significant advantages over the other tests evaluated its dynamic range and was consistently higher than any of the other methods evaluated; it allows the evaluation of both near-and far field shielding (using theoretical calculations), so that both emission and susceptibility problems could be addressed; and there was less variability from location to location. It is concluded that this fixture is the most useful for repeatable material ranking.<>