Recent advances in structural design of conductive polymer composites for electromagnetic interference shielding
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Abstract The proliferation of electronic devices and wireless communication in our daily lives has led to a significant increase in electromagnetic pollution. This issue poses a serious threat to the proper functioning of electronic equipment as well as human health. Therefore, the investigation of materials with superior electromagnetic interference (EMI) shielding capabilities has garnered growing interest. In this paper, the mechanisms of EMI shielding were first introduced briefly. It was noted that the development of advanced EMI shielding materials involved adhering to principles such as minimizing reflection loss, enhancing absorption loss, and incorporating multiple internal reflections. The construction and shielding properties of traditional EMI shielding materials were introduced. Unlike metal materials with high densities and reflection loss, lightweight conductive polymer composites (CPCs) have been the most promising EMI shielding materials. Meanwhile, carbon‐based nanofillers such as carbon nanotubes and graphene nanosheets, along with two‐dimensional transition metal carbonitrides MXenes Ti 3 C 2 T x , have emerged as the most promising and versatile conductive nanofillers for CPCs. The EMI shielding performance and loss mechanism of CPCs with homogeneous structure, segregated structure, laminated structure, and porous structure were introduced in detail. It was noted that the EMI shielding performance could be significantly improved by incorporating multiple structures into the same CPCs, such as a rational combination of segregated and porous structures. Finally, the challenges and development trends of CPCs for EMI shielding applications were discussed. Highlights Mechanisms of EMI shielding were introduced from aspect of energy dissipation. Structure–property of traditional EMI shielding materials was described. EMI shielding performance of CPCs with different structures was summarized. Future challenges and growing trends of CPCs for EMI shielding were discussed. Absorption‐dominated loss and multiple structure design were emphasized.Cite
A super network was built in this paper to describe the interconnections between electromagnetic interference (EMI) and electromagnetic compatibility (EMC) indicators. And EMI network was divided into three clusters according to the basic components of EMI. Then some features of the super network were analysed to character the relationships among indicators and nodes of EMI network, which will support the EMC predesign of the electronic system.
Electromagnetic Compatibility
Electromagnetic environment
Conducted electromagnetic interference
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Flexible and wearable electromagnetic interference (EMI) shielding material is one of the current research focuses in the field of EMI shielding. In this work, for the first time, WS2-carbon fiber (WS2-CF) composites are synthesized by implanting WS2, which has a multiphase structure and a large number of defects, onto the surface of carbon fiber (CF) by using a simple one-step hydrothermal method, and are applied to protect electronic devices from EMI. It is found that the EMI shielding performance of WS2-CF is significantly improved, especially for those at S and C-bands. At 2 GHz, the EMI shielding efficiency could reach 36.0 dB at a typical thickness of 3.00 mm of the composite, which is much better than that of pure CF (25.5 dB). Besides paving a novel avenue to optimize the electromagnetic shielding performance of flexible and wearable CF-based EMI shielding materials, which have great potential in the practical application for EMI shielding, this work provides a new paradigm for the design and synthesis of EMI shielding materials which have a broad application prospect.
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Electromagnetic interference/electromagnetic compatibility (EMI/EMC) prediction models and techniques, and analysis tools are being widely developed and used for radio frequency systems. However, given that electro optical (EO) and infrared (IR) systems also utilise the electromagnetic spectrum, it is important that the EMI/EMC concept should also be extended to incorporate EO and IR systems. There are currently no prediction models and technique or analysis tools available to assess EMI/EMC of EO and IR systems. This paper presents an EMI/EMC modelling prediction method, which has been applied on a number of test cases to assess EMI/EMC for EO and IR systems.
Electromagnetic Compatibility
Conducted electromagnetic interference
Electromagnetic spectrum
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Abstract : In recent years a significant number of digital devices and systems have been added to receiving and data-processing sites. These additions have enhanced the ability of the sites to accomplish their mission. They have also introduced new kinds of electromagnetic interference (EMI) into these sites along with accompanying performance degradation problems. In this thesis one specific case of EMI is considered. It is EMI from a digital climate-control system of a building housing a data-processing facility. The digital system generated excessive amounts of EMI. The EMI was conducted throughout the site over power and control conductors. Electromagnetic fields from EMI current flowing in these conductors coupled the EMI into other nearby conductors. Integrated barrier, filter, and ground techniques were used to reduce the conducted and radiated EMI to harmless levels. Electromagnetic interference, Electromagnetic compatibility, Barriers filters, Grounds, Variable-Frequency drive controller, Variable speed motors, EMI standards.
Electromagnetic Compatibility
Conducted electromagnetic interference
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EMI is everywhere, inside and outside of all electrical equipment. Man-made EM1 is on the increase daily, due to the increased use of electrical and electronic equipment. The successful detection and elimination of EMI require a systematic search for EM1 sources as well as knowledge of interference susceptibilities of the equipment. Familiarity with the environment in which the equipment will work as well as possible alternative environments are fundamental to effective EMI reduction to a required minimum level. In this paper we designed a simple two wire model to predict EMI when this model is illuminated by a distant source antenna. The proposed model is being fabricated at Indian Institute of Technology, India. Measured and simulated results are shown. Simulations were being carried out at Kalpana Chawla Space Technology Cell, IIT Kharagpur, India.
Electromagnetic Compatibility
Pickup
Conducted electromagnetic interference
Electromagnetic environment
Antenna height considerations
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The environment problem of Electromagnetic Interference (EMI) becomes more and more outstanding. This problem has already influenced people's life in different degree. In this paper, the basic concepts and hazards of EMI are introduced. After that, anti-EMI components upon the material and anti-EMI system design are introduced. Finally, the significance of developments on anti-EMI technology is pointed out.
Conducted electromagnetic interference
Electromagnetic Compatibility
Electromagnetic environment
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최근 통신기술은 5G 및 10 Gbps 이더넷 기술의 상용화로 인한 데이터 속도 및 고주파 노이즈의 증가로 방사성 EMI(electro magnetic interference)가 증가하고 있다. 이러한 EMI의 발생은 주변 전자기기들에 영향을 미쳐 오동작 원인이 될 가능성이 높다. 또한 CPU 및 통신소자의 부하증가로 인한 고열 발생으로 히트 싱크(Heat sink)의 사용도 필수적이다. 그러나 히트 싱크는 통신기기의 내부로부터 발생되는 전자파를 외부로 방출시키는 안테나 역할을 할 수 있다. 본 연구에서는 히트 싱크를 사용한 통신기기의 방사성 EMI를 개선하기 위한 연구로서 히트 싱크와 PCB 접점에 방사성 EMI 필터를 적용하였다. EMI 필터는 소형화 및 실장이 용이한 다층 세라믹 커패시터(MLCC)를 사용하였으며, 1, 33, 100 pF 용량의 MLCC를 각각 사용하였다. EMI 시험은 통신기기와 안테나의 거리 3 m 위치에서 국제표준 및 국내 전파법 기준에 따라 전자파 무향실에서 진행하였다. MLCC를 적용하지 않은 경우, 발생되는 방사성 EMI는 허용 기준치를 초과하였다. 1 및 33 pF의 MLCC를 각각 적용한 경우, 방사성 EMI는 저감되었으나, 특정 주파수에서 허용 기준치를 초과하였으며, 100 pF의 MLCC를 적용 시에 허용 기준을 만족하였다. 또한 방사성 EMI 필터의 적용은 전도성 EMI에 영향이 없음을 확인하였다. 결론적으로 히트 싱크와 PCB 접지 사이의 MLCC 필터를 사용하여, 시스템 방사성 EMI 노이즈가 발생하는 주파수대역 차단으로 방사성 EMI를 저감 시켰으며, 히트 싱크 구조를 활용한 EMI 필터의 설계 방향을 제시하였다.
Conducted electromagnetic interference
Electromagnetic Compatibility
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With rapid development of 5G communication technologies, electromagnetic interference (EMI) shielding for electronic devices has become an urgent demand in recent years, where the development of corresponding EMI shielding materials against detrimental electromagnetic radiation plays an essential role. Meanwhile, the EMI shielding materials with high flexibility and functional integrity are highly demanded for emerging shielding applications. Hitherto, a variety of flexible EMI shielding materials with lightweight and multifunctionalities have been developed. In this review, we not only introduce the recent development of flexible EMI shielding materials, but also elaborate the EMI shielding mechanisms and the index for "green EMI shielding" performance. In addition, the construction strategies for sophisticated multifunctionalities of flexible shielding materials are summarized. Finally, we propose several possible research directions for flexible EMI shielding materials in near future, which could be inspirational to the fast-growing next-generation flexible electronic devices with reliable and multipurpose protections as offered by EMI shielding materials.
Electromagnetic Compatibility
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All clinical MRI scanners require bulky and enclosed RF shielding rooms to prevent external electromagnetic interference (EMI) signals during data acquisition, and quality electronics inside shielding room (i.e., with minimal EMI emission). A deep learning EMI cancellation strategy is presented to model, predict and remove EMI signals from acquired MRI signals, eliminating the need for RF shielding. We demonstrated that this method worked robustly for various EMI sources from both external environments and internal scanner electronics, producing final image SNRs highly comparable to those obtained using a fully enclosed RF shielding cage in 0.055T and 1.5T experiments.
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Electromagnetic interference (EMI) shielding is critical in electronic applications. However, the currently available EMI shielding materials are restricted in customizability and application flexibility. Recent advances in manufacturing technologies have provided a unique path to achieve the custom creation of EMI shielding solutions. A successful example is additive manufacturing (AM), which has enabled high design freedom, efficient performance regulation, and multifunctionality simultaneously into fabricated shields, offering an opportunity to start a revolution in the field of EMI shielding. In this review, we summarize the latest advances in AM of EMI shielding materials, aiming to provide a deep understanding of the connection between raw materials, manufacturing methods, design considerations, and performances of the fabricated EMI shields. We first introduce the EMI shielding mechanism and available raw materials, subsequently focusing on the characteristics of representative AM methods and the as-created EMI shielding solutions. Based on the requirements to create application-oriented EMI shielding solutions, these methods are also critically compared. Thereafter, we present the state-of-the-art design considerations of EMI shields and examine the pivotal roles of AM in realizing the designs. We conclude by discussing future research directions, aiming at motivating the use of AM in the future developments of EMI shielding solutions.
Shields
Electromagnetic Compatibility
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