scholarly journals Analysis of the effect of different absorber materials and loading on the shielding effectiveness of a metallic enclosure

2015 ◽  
Vol 13 ◽  
pp. 155-159 ◽  
Author(s):  
S. Parr ◽  
H. Karcoon ◽  
S. Dickmann ◽  
R. Rambousky
Keyword(s):  
Complex System ◽  
Electromagnetic Interference ◽  
Electromagnetic Shielding ◽  
Electronic Equipment ◽  
Shielding Effectiveness ◽  
Resonant Frequencies ◽  
Parameter Variations ◽  
Electromagnetic Shielding Effectiveness ◽  
Dielectric Structures

Abstract. Metallic rooms as part of a complex system, like a ship, are necessarily connected electromagnetically via apertures and cables to the outside. Therefore, their electromagnetic shielding effectiveness (SE) is limited by ventilation openings, cable feed-throughs and door gaps. Thus, electronic equipment inside these rooms is susceptible to outer electromagnetic threats like IEM (Intentional Electromagnetic Interference). Dielectric or magnetic absorber inside such a screened room can be used in order to prevent the SE from collapsing at the resonant frequencies. In this contribution, the effect of different available absorber materials is compared, as well as other properties like weight and workability. Furthermore, parameter variations of the absorber as well as the effect of loading in form of metallic and dielectric structures on the SE are analyzed.

scholarly journals Electromagnetic Shielding Effectiveness of Woven Fabrics with High Electrical Conductivity: Complete Derivation and Verification of Analytical Model

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1657 ◽  
Author(s):  
Marek Neruda ◽  
Lukas Vojtech
Keyword(s):  
Electrical Conductivity ◽  
Analytical Model ◽  
Electromagnetic Interference ◽  
Woven Fabrics ◽  
Electromagnetic Shielding ◽  
High Electrical Conductivity ◽  
Shielding Effectiveness ◽  
Textile Composite ◽  
A Value ◽  
Electromagnetic Shielding Effectiveness

In this paper, electromagnetic shielding effectiveness of woven fabrics with high electrical conductivity is investigated. Electromagnetic interference-shielding woven-textile composite materials were developed from a highly electrically conductive blend of polyester and the coated yarns of Au on a polyamide base. A complete analytical model of the electromagnetic shielding effectiveness of the materials with apertures is derived in detail, including foil, material with one aperture, and material with multiple apertures (fabrics). The derived analytical model is compared for fabrics with measurement of real samples. The key finding of the research is that the presented analytical model expands the shielding theory and is valid for woven fabrics manufactured from mixed and coated yarns with a value of electrical conductivity equal to and/or higher than σ = 244 S/m and an excellent electromagnetic shielding effectiveness value of 25–50 dB at 0.03–1.5 GHz, which makes it a promising candidate for application in electromagnetic interference (EMI) shielding.

Study to Wood Electromagnetic Shielding Composites Laminated with Aluminum Plates

2011 ◽  
Vol 280 ◽  
pp. 159-164 ◽  
Author(s):  
Ke Yang Lu ◽  
Feng Fu ◽  
Yue Jin Fu ◽  
Zhi Yong Cai
Keyword(s):  
Electromagnetic Interference ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Building Product ◽  
Static Modulus ◽  
Electrical Devices ◽  
Aluminum Plates ◽  
Static Modulus Of Elasticity ◽  
Electromagnetic Shielding Effectiveness ◽  
Shielding Composites

Radiations from different electrical devices cause electromagnetic interference which will influence the performance realization of other electromagnetic device and cause the health concerns. The aluminum plates were then used to develop wood electromagnetic shielding composites by laminating with the plywood. Their static modulus of elasticity and electromagnetic shielding effectiveness of the composites with different thickness and position of aluminum plates were evaluated. The results showed that the strength of composites were improved by laminating the aluminum plates on the surface. The electromagnetic shielding performance of the composites were increased by the design of the multilayer and sandwich shielding structure. Again, It was also found that the composites made by laminating two aluminum plates (1mm, in the middle or on the surface) had a better shielding effectiveness (60 dB to 92 dB, 60 dB to 106 dB, Ranged from 1 GHz to 10 GHz) and met the requirement for a commercial electromagnetic shielding building product.

The Influence of Fabric Structures of the Woven Fabrics on Electromagnetic Shielding Effectiveness

2011 ◽  
Vol 239-242 ◽  
pp. 1994-1997 ◽  
Author(s):  
Ching Wen Lou ◽  
Yi Chang Yang ◽  
Chin Mei Lin ◽  
Ching Wen Lin ◽  
Lin Chao Chen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Electromagnetic Interference ◽  
Woven Fabrics ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Fabric Structures ◽  
Electromagnetic Shielding Effectiveness

Stainless steel (SS) blended yarns with electromagnetic interference (EMI) were made into woven fabrics, after which the fabrics were evaluated with electromagnetic shielding effectiveness (EMSE). Parameters of laminated angle and the lamination number layers affected the fabrics’ EMSE differently. In addition, density of unidirectional SS yarns affected EMSE in frequency range of 200 to 500 MHz , so as the density of cross SS yarns on a frequency over 1000 MHz.

scholarly journals Multilayer-Structured Wood Electroless Cu–Ni Composite Coatings for Electromagnetic Interference Shielding

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 740
Author(s):  
Yanfei Pan ◽  
Dingwen Yin ◽  
Xiaofang Yu ◽  
Nanyi Hao ◽  
Jintian Huang
Keyword(s):  
Surface Roughness ◽  
Surface Morphology ◽  
Electromagnetic Interference ◽  
Composite Coatings ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Electromagnetic Interference Shielding ◽  
Electromagnetic Shielding Effectiveness ◽  
The Ideal

The lightweight multilayer-structured electromagnetic interference shielding composite coatings with controllable electromagnetic gradient on wood surface were prepared via a simple multiple electroless copper–nickel (Cu–Ni) approach. The surface morphology, conductivity, hydrophobicity property and electromagnetic shielding effectiveness of the composite coatings were investigated. The surface roughness and conductivity of the composite coatings were enhanced with the increase in the number of depositions. The surface morphology demonstrated that the roughness was decreased with the process of multiple electroless. The coatings were compact and homogeneous as the deposition run was three. Here, the Sa (Sa illustrated Surface Roughness) value of coatings was 4.497 μm. The ideal conductivity of composite coatings can be obtained as the number of depositions was four. Electromagnetic shielding effectiveness reached average 90.69 dB in the frequency range from 300 kHz to 2.0 GHz. This study provides a new pathway for fabricating lightweight multilayer-structured electromagnetic interference shielding with controllable electromagnetic gradient and hydrophobic composite coatings-based wood.

Mechanical performance and electromagnetic shielding effectiveness of composites based on Ag-plating cellulose micro-nano fibers and epoxy

2017 ◽  
Vol 37 (8) ◽  
pp. 805-813 ◽  
Author(s):  
Yu Wang ◽  
Jin Tian Huang
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Interference ◽  
Mechanical Performance ◽  
Oxide Phase ◽  
Cellulose Fibers ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Emi Shielding Effectiveness ◽  
Nano Cellulose ◽  
Electromagnetic Shielding Effectiveness

Abstract Mechanical and electromagnetic interference shielding composites containing Ag-plating micro-nano cellulose fibers (ANCFs) were prepared as multifunctional materials. ANCFs, as electromagnetic wave reflection filler containing micro-nano cellulose fibers (NCFs) used as the structural component to reinforce the mechanical strength and Ag enhancing electromagnetic shielding effectiveness, were prepared by electroless Ag-plating technology on NCFs surfaces. Ag coating had a thickness of 60 µm without the oxide phase detected. The incorporation of 5 wt % ANCFs into epoxy (EP) substrate yielded impact strength and flexural strength of 1.84 kJ/m2 and 41.6 MPa, which is approximately 2.4 times and 1.41 times higher than EP. The ANCFs-EP composite performed an electromagnetic shielding effectiveness of 34–25 dB at a frequency of 90 kHz in the electromagnetic wave; the EMI shielding effectiveness was improved obviously up to 34 dB, which can meet the requirement of general places.

Electromagnetic Shielding of Multi-Walled Carbon Nanotube/Epoxy Nanocomposites

2008 ◽  
Vol 47-50 ◽  
pp. 475-478 ◽  
Author(s):  
Meng Kao Yeh ◽  
Nyan Hwa Tai ◽  
Guo Chian Ling ◽  
Chi Yuan Huang
Keyword(s):  
Carbon Nanotubes ◽  
Electromagnetic Interference ◽  
Chemical Vapor ◽  
Electromagnetic Shielding ◽  
Tensile Failure ◽  
Chemical Vapor Deposition Method ◽  
Shielding Effectiveness ◽  
Spreading Process ◽  
Weight Percentage ◽  
Electromagnetic Shielding Effectiveness

In this paper, carbon nanotubes were used as the reinforcements in the polymer composites for the application of electromagnetic interference, due to their outstanding mechanical and electrical properties. The multi-walled carbon nanotubes (MWNTs) synthesized by the chemical vapor deposition method were used to reinforce the epoxy resin by both mixing and spreading processes. The effects of the weight percentage and the reinforced form of MWNTs on electromagnetic interference shielding effectiveness, including the absorbance and the reflectance, were investigated. From experimental results, the electromagnetic shielding effectiveness of the nanocomposite specimens is improved with increasing content of MWNTs. The nanocomposites fabricated by the spreading process have better shielding effectiveness than those made by the mixing process. The nanocomposites, made by the spreading process with 2 wt% MWNTs, had up to 22.69 dB of electromagnetic shielding effectiveness. The reflectance percentage of electromagnetic shielding increases for higher content of MWNTs. The layerwise form of MWNTs in the nanocomposites, resulting from the spreading process and having a better electromagnetic shielding effectiveness, can be observed from the morphologies of the tensile failure surfaces of the nanocomposite specimens by filed emission scanning electron microscopy.

scholarly journals Electromagnetic Shielding Effectiveness and Conductivity of PTFE/Ag/MWCNT Conductive Fabrics Using the Screen Printing Method

2020 ◽  
Vol 12 (15) ◽  
pp. 5899
Author(s):  
Hung-Chuan Cheng ◽  
Chong-Rong Chen ◽  
Shan-hui Hsu ◽  
Kuo-Bing Cheng
Keyword(s):  
Electrical Conductivity ◽  
Electromagnetic Interference ◽  
Electromagnetic Shielding ◽  
Multiwall Carbon Nanotube ◽  
Shielding Effectiveness ◽  
Ptfe Film ◽  
Conductive Films ◽  
Hybrid Grid ◽  
Electromagnetic Shielding Effectiveness ◽  
Mwcnt Loading

The management of the electromagnetic interference (EMI) of thin, light, and inexpensive materials is important for consumer electronics and human health. This paper describes the development of conductive films that contain a silver (Ag) flake powder and multiwall carbon nanotube (MWCNT) hybrid grid on a polytetrafluoroethylene (PTFE) film for applications that require electromagnetic shielding (EMS) and a conductive film. The Ag and MWCNT hybrid grid was constructed with a wire diameter and spacing of 0.5 mm. The results indicated that the proposed conductive films with 0.4 wt% MWCNTs had higher electromagnetic shielding effectiveness (EMSE) and electrical conductivity than those with other MWCNT loading amounts. The results also showed that the film with 0.4 wt% MWCNT loading had a high 62.4 dB EMSE in the 1800 MHz frequency and 1.81 × 104 S/cm electrical conductivity. This combination improved stretchability, with 10% elongation at a 29% resistivity change rate. Conductive films with Ag/MWCNT electronic printing or lamination technologies could be used for EMI shielding and electrically conductive applications.

A highly stretchable, easily processed and robust metal wire-containing woven fabric with strain-enhanced electromagnetic shielding effectiveness

2021 ◽  
pp. 004051752199489 ◽  
Author(s):  
Yong Wang ◽  
Stuart Gordon ◽  
Weidong Yu ◽  
Zongqian Wang
Keyword(s):  
Electromagnetic Interference ◽  
Specular Reflection ◽  
Electronic Devices ◽  
Single Layer ◽  
Electromagnetic Shielding ◽  
Woven Fabric ◽  
Shielding Effectiveness ◽  
Fabric Structure ◽  
Highly Stretchable ◽  
Electromagnetic Shielding Effectiveness

Textiles that contain integrated conducting components are drawing attention for their ability to mitigate electromagnetic radiation pollution. Maintaining effective and robust electromagnetic shielding effectiveness (EMSE) under different modes, e.g. stretching, bending and washing, is of importance in protecting humans and information-sensitive electronic devices from exposure to electromagnetic interference. In this work, a weft-stretchable, conductive fabric (W-SCF) was specially manufactured for electromagnetic shielding characterization by integrating stainless steel filament (SSF) in the weft direction. The results demonstrate that our as-prepared W-SCF was effective for shielding purpose with its EMSE dependent on the orientation of the SSF within the fabric structure. Specular reflection caused by the close arrangement of the SSF and the lower electrical resistance of the fabric on per unit area basis were responsible for the enhanced shielding properties when the fabric was stretched. Furthermore, using the fabric in a 90°/90° laminated form improved the EMSE values compared with a single layer and a 0°/90° laminated versions. Importantly, the W-SCF exhibited resistance to 10 laundering cycles, 20 stretching cycles (at 25% extension), 50 bending cycles and 100 abrasion cycles, demonstrating its robustness and durability. This work is believed to take a new step in development of reliable and advance shielding materials for special protective application.

scholarly journals Ultrathin Multilayer Textile Structure with Enhanced EMI Shielding and Air-Permeable Properties

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4176
Author(s):  
Shi Hu ◽  
Dan Wang ◽  
Aravin Prince Periyasamy ◽  
Dana Kremenakova ◽  
Jiri Militky ◽  
...  
Keyword(s):  
Electromagnetic Interference ◽  
Single Layer ◽  
Electromagnetic Shielding ◽  
Shielding Effect ◽  
Material Surface ◽  
Test Results ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Emi Shielding Effectiveness ◽  
Electromagnetic Shielding Effectiveness

A textile material’s electromagnetic interference (EMI) shielding effectiveness mainly depends on the material’s electrical conductivity and porosity. Enhancing the conductivity of the material surface can effectively improve the electromagnetic shielding effectiveness. However, the use of highly conductive materials increases production cost, and limits the enhancement of electromagnetic shielding effectiveness. This work aims to improve the EMI shielding effectiveness (EMSE) by using an ultrathin multilayer structure and the air-permeable textile MEFTEX. MEFTEX is a copper-coated non-woven ultrathin fabric. The single-layer MEFTEX SE test results show that the higher its mass per unit area (MEFTEX 30), the better its SE property between 56.14 dB and 62.53 dB in the frequency band 30 MHz–1.5 GHz. Through comparative testing of three groups samples, a higher electromagnetic shielding effect is obtained via multilayer structures due to the increase in thickness and decrease of volume electrical resistivity. Compared to a single layer, the EMI shielding effectiveness of five layers of MEFTEX increases by 44.27–83.8%. Due to its ultrathin and porous structure, and considering the balance from porosity and SE, MEFTEX 10 with three to four layers can still maintain air permeability from 2942 L/m2/s–3658 L/m2/s.

Polypyrrole and silver particles coated poly(ethylene terephthalate) nonwoven composite for electromagnetic interference shielding

2017 ◽  
Vol 52 (10) ◽  
pp. 1353-1362 ◽  
Author(s):  
Meryem Kalkan Erdoğan ◽  
Meral Karakışla ◽  
Mehmet Saçak
Keyword(s):  
Electromagnetic Interference ◽  
Ethylene Terephthalate ◽  
Electromagnetic Shielding ◽  
Scanning Electron Micrographs ◽  
Silver Particles ◽  
Shielding Effectiveness ◽  
Poly Ethylene Terephthalate ◽  
Ag Particles ◽  
Poly Ethylene ◽  
Electromagnetic Shielding Effectiveness

A conductive polypyrrole/silver/poly(ethylene terephthalate) composite was prepared by the polymerization of pyrrole with AgNO3 oxidant in the presence of poly(ethylene terephthalate) nonwoven. The effect of AgNO3/pyrrole mol ratio and concentrations of the reactants was investigated on the polypyrrole/silver content and surface resistivity of the composite. The deposition of shiny metallic Ag particles was observed on the composite during the polymerization of pyrrole. The weight fraction of the Ag particles in the polypyrrole/silver contents of the composite was determined by thermogravimetric analysis. It was observed from scanning electron micrographs that the morphology of the polypyrrole/silver particles changed with the increase in the polypyrrole/silver contents of the composite. The electromagnetic shielding effectiveness as well as the absorption loss, reflection loss with the values of absorbance and reflectance, showing their contributions to the electromagnetic shielding effectiveness value of the composite were determined within the frequency range of 15–3000 MHz. An absorption dominant shielding was obtained with the value of 13–15.5 desibel for double coated composite.

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