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Shielding Effectiveness Measurement With Wide Dynamic Range for a Small Enclosure in a Nested Reverberation Chamber

For a small shielding enclosure, its shielding effectiveness (SE) is measured using the frequency-domain method that is defined in the IEEE 299.1 standard. The frequency-domain method, however, has a reduced dynamic range so that a high level of SE is measured inaccurately. Such dynamic range reduction in SE measurement is caused by cable coupling of transmitting signal during measurement. This article proposes a time-domain method that measures even a high level of SE accurately. Unlike the frequency-domain method, the proposed method does not experience dynamic range reduction. Instead of a continuous wave signal, a pulse signal is transmitted in a nested reverberation chamber for SE measurement. After the pulse transmission, a receiving signal is measured and sampled for the SE calculation. The receiving signal is sampled only after the transmitting pulse signal dissipates completely in the nested reverberation chamber. As a result, the cable coupling and dynamic range reduction do not occur in proposed time-domain method. The proposed time-domain method extends a dynamic range over 30 dB in comparison with the frequency-domain method. The proposed method can measure a high level of SE over 120 dB accurately without being affected by the cable coupling.