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.

中文翻译：

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嵌套混响室中小型外壳的宽动态范围屏蔽效能测量


对于小型屏蔽罩，其屏蔽效能（SE）是使用IEEE 299.1标准中定义的频域方法来测量的。然而，频域方法的动态范围较小，因此无法准确测量高水平的 SE。 SE 测量中的这种动态范围减小是由测量期间传输信号的电缆耦合引起的。本文提出了一种时域方法，可以准确测量高水平的 SE。与频域方法不同，所提出的方法不会经历动态范围减小。代替连续波信号，脉冲信号在嵌套混响室中传输以进行 SE 测量。脉冲发送后，对接收信号进行测量和采样以进行 SE 计算。只有当发射脉冲信号在嵌套混响室中完全消散后，才对接收信号进行采样。因此，所提出的时域方法不会发生电缆耦合和动态范围减小。与频域方法相比，所提出的时域方法将动态范围扩展了 30 dB 以上。该方法可以准确测量超过 120 dB 的高电平 SE，而不受电缆耦合的影响。