Return Loss Removal in Shielding Effectiveness Measurement Using IEEE 299.1

Abstract

In this article, a method for removing the return loss effect during shielding effectiveness (SE) measurements for a shielding enclosure is proposed. According to the IEEE 299.1 standard, a receiving antenna is located inside the enclosure to be measured, and this antenna measures the signal loss after passing through the enclosure. The receiving antenna experiences the return loss at its input, and this return loss increases the SE because the occurrence of the return loss is equivalent to the increasing loss when passing through the enclosure. The IEEE 299.1 standard provides a method for removing the return loss effect. The return-loss removal is only effective, however, when the receiving antenna has an input impedance that does not significantly change, remaining almost constant at the adjacent frequencies. The proposed method generalizes the return-loss removal, and thus the return loss effect can be removed irrespective of the input impedance condition of the receiving antenna. As the return loss is removed for any type of the receiving antenna, the SE can be accurately measured to prevent an overestimation of the SE.