Study on differences of the electromagnetic shielding effectiveness caused by differences in measuring methods and test sample area

Comparative electromagnetic compatibility investigations were carried out to study: differences in values of electromagnetic shielding effectiveness measured by different methods; and divergences between the results according to the size of the measured objects, with the MIL-STD-285 method taken as an example to elucidate the shielding effectiveness of building materials, installations, etc. Different evaluation methods, i.e. the transmission and insertion loss methods, are shown to cause difference in measured effectiveness values, which depend on the dimension of the test material. In regard to differences of the test sample surface area, evaluation according to the transmission loss method showed no significant differences, but evaluation according to the insertion loss method showed an apparent decrease of the effectiveness with decreasing surface area of the test sample