混响室法欠模状态屏蔽体屏蔽效能测试技术研究

欠模状态下屏蔽壳体内部场分布不均匀,屏蔽效能测量结果与位置相关,因此需要利用探头或单极子天线进行多位置测量,过程繁琐。文中利用长线天线来测量欠模状态下屏蔽壳体屏蔽效能,并与单极子天线测量结果进行比较。在暗室中测量天线自由空间反射系数S₁₁;在混响室中利用不同天线测量屏蔽壳体的屏蔽效能,并利用S₂₂分析腔体谐振特性。测量结果表明,长线天线宽频带匹配特性优于单极子天线,测量的屏蔽效能能够更好地反映屏蔽体谐振特性,为屏蔽壳体的屏蔽效能测试评估提供了指南,具有工程应用价值。

Research on Test Techniques for Shielding Effectiveness of Undermoded Enclosure in Reverberation Chamber

Due to the non-uniform distribution of electromagnetic field in undermoded enclosure, the measurement results of the shielding effectiveness are related to the position. Therefore, it is necessary to use a probe or a monopole antenna for multi-position measurement which is cumbersome. In this study, the long-wire antenna was used to measure the shielding effectiveness of the enclosure under the undermoded state, and compared with the monopole antenna measurements. The free-space reflection coefficient S₁₁ of the antenna was measured in anechoic chamber. The shielding effectiveness of the shielding shell was measured by different antennas in the reverberation chamber, and the cavity resonance characteristic was analyzed with S₂₂. The experiment results showed that the long-wire antenna had better broadband matching characteristic than the monopole antenna, and the measured shielding effectiveness could better reflect the resonant characteristics of the enclosure, which provided guidance for shielding effectiveness evaluation of enclosures and had engineering application value.