Electromagnetic interference shielding effectiveness of conformal structures based on near-field scanning: A review

In recent years, near-field scanning technology has emerged as a critical tool for analyzing and mitigating electromagnetic interference (EMI) in electronic devices. This article provides an in-depth examination of the principles, techniques, and applications of near-field scanning, focusing on its relevance in evaluating the shielding effectiveness of conformal shielding structures. Various methods for defining near-field shielding effectiveness, such as fixed-point, maximum radiation field, and average magnetic field-based approaches, are discussed in detail. Furthermore, the limitations of existing near-field probes, the need for comprehensive testing standards, and the challenges in developing accurate algorithms for localizing unknown radiation sources are explored. A detailed account of the various definitions of near-field shielding effectiveness is provided, comparing their advantages and drawbacks. Through theoretical analysis and examples, it is demonstrated that the average magnetic field-based definition is more suitable for evaluating the shielding ability of structures, particularly in the frequency range of 1 GHz to 18 GHz. Research gaps in near-field scanning technology are addressed, emphasizing the importance of advancements in probe technology, the development of standardized testing procedures, and the improvement of algorithms for localizing unknown radiation sources. Advancing the field of near-field scanning will enhance the understanding and mitigation of EMI, ensuring the performance and reliability of electronic devices in an increasingly connected world.