The conventional definition of shielding effectiveness (SE) is well suited for calculations of far-field electromagnetic shielding. However, in the near field, SE calculations are not as straightforward. In radio-frequency interference (RFI) problems, the majority of field coupling occurs in the near field. Thus, a well-defined method for calculating the near-field SE is needed to estimate the suppression of RFI achieved by shielding cans. In this study, a method based on near-field scanning is developed to extract the SE of board-level shielding cans. The SE is defined by modeling the shielded noise source as equivalent dipole moments. The accuracy of the equivalent source is analyzed via the least-square error and correlation coefficient as confidence verification parameters. By applying the reciprocity theorem, the voltage coupled on a planar inverted F antenna from an unshielded and a shielded source is calculated. The coupled voltage from a shielded noise source serves as a reference to validate the effectiveness of the proposed method. Practical shielding cans were used to develop and validate the SE extraction method using full-wave 3D simulations and measurements.

中文翻译：

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基于近场扫描的板级屏蔽罐屏蔽效能提取

屏蔽效能 (SE) 的传统定义非常适合远场电磁屏蔽的计算。然而，在近场中，SE 计算并不那么简单。在射频干扰 (RFI) 问题中，大部分场耦合发生在近场中。因此，需要一种用于计算近场 SE 的明确定义的方法来估计屏蔽罐实现的 RFI 抑制。在这项研究中，开发了一种基于近场扫描的方法来提取板级屏蔽罐的 SE。SE 是通过将屏蔽噪声源建模为等效偶极矩来定义的。通过最小二乘误差和相关系数作为置信度验证参数来分析等效源的准确性。通过应用互易定理，计算从非屏蔽源和屏蔽源耦合到平面倒 F 天线上的电压。来自屏蔽噪声源的耦合电压可作为验证所提出方法有效性的参考。实用的屏蔽罐用于开发和验证使用全波 3D 模拟和测量的 SE 提取方法。