scholarly journals Measuring of Shielding Effectiveness of Electromagnetic Field of Polystyrene in the Frequency Range from 1 GHz to 9 GHz

2014 ◽  
Vol 32 ◽  
pp. 46
Author(s):  
Marek Pavlík ◽  
Iraida Kolcunová ◽  
Ján Zbojovský ◽  
Dušan Medved
Keyword(s):  
Electromagnetic Field ◽  
Shielding Effectiveness ◽  
Frequency Range

scholarly journals Impact of Absorbers on the Shielding Effectiveness of Metallic Rooms with Apertures

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 237
Author(s):  
Jong Hwa Kwon ◽  
Chang Hee Hyoung ◽  
Jung-Hwan Hwang ◽  
Hyun Ho Park
Keyword(s):  
Numerical Simulation ◽  
Electromagnetic Field ◽  
Resonant State ◽  
Standing Waves ◽  
Resonant Mode ◽  
Q Factor ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Theoretical Formulation ◽  
Full Wave

An electromagnetic field penetrating through an aperture or slot of a metallic enclosure generates many standing-waves due to the resonance inside the metallic enclosure, which results in reduced shielding performance. This paper examines the effect of absorbent material (absorber) to improve shielding effectiveness (SE) of large metallic rooms with apertures or slots. First, a theoretical formulation to extract the Q-factor of an absorber with any shape is proposed. Using this, the contribution of the absorber to the SE improvement of a shielded room with different sized circular apertures was investigated. Second, the resonant mode density inside the shielded room was classified into non-resonant, under-moded, and over-moded states with an increase in frequency, and the effect of the absorber in each frequency range was examined. The analysis was conducted through numerical simulation using a commercial full-wave simulator and experimental measurement using a fabricated actual shielded room and commercial absorbers. The accuracy of the analysis results was verified through the comparison of simulated and measured results. The analysis results ensured that the absorber was not effective in improving the SE in the non-resonant state of the metallic room. It was also confirmed that the absorber was effective in improving the SE in the over-moded state of the metallic room where a severe standing-wave occurs. In addition, the SE improvement level differed depending on the location of the absorber in the room.

scholarly journals Conductive textile structures and their contribution to electromagnetic shielding effectiveness

2020 ◽  
Vol 71 (05) ◽  
pp. 432-437
Author(s):  
Ion Razvan Radulescu ◽  
Lilioara Surdu ◽  
Bogdana Mitu ◽  
Cristian Morari ◽  
Marian Costea ◽  
...  
Keyword(s):  
Electromagnetic Compatibility ◽  
Modern Technology ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Conductive Coatings ◽  
Tem Cell ◽  
Conductive Yarns ◽  
Conductive Textile ◽  
Electromagnetic Shielding Effectiveness

Fabrics for electromagnetic shielding are especially relevant in nowadays context, contributing to human’s protection and wellbeing and to proper functioning of electronic equipment, in relation to electromagnetic compatibility. Fabrics with electromagnetic shielding properties employ two main technologies, namely insertion of conductive yarns and application of conductive coatings. Magnetron sputtering is a modern technology to enable conductive coatings with thickness in the range of nanometers onto fabrics. This paper aims to analyze contribution of various conductive textile structures out of both fabrics with inserted conductive yarns and coatings to Electromagnetic shielding effectiveness (EMSE). EMSE was measured in the frequency range of 0.1–1000 MHz by using a TEM cell according to standard ASTM ES-07. Results show a gain of 10–25 dB when introducing silver yarns in warp/ weft direction, a variation of 5–35 dB between conductive yarns out of silver and stainless steel and an up to 12 dB gain out of thin copper coating by magnetron plasma onto the fabrics with inserted conductive yarns

Electromagnetic shielding performance of three-dimensional woven fabrics with copper-based hybrid yarn in X-band frequency range

2018 ◽  
Vol 49 (4) ◽  
pp. 484-502 ◽  
Author(s):  
Dharmendra Nath Pandey ◽  
Arindam Basu ◽  
Pramod Kumar ◽  
Himangshu B Baskey
Keyword(s):  
Cotton Fabric ◽  
Three Dimensional ◽  
Electromagnetic Shielding ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Structural Configuration ◽  
Band Frequency ◽  
Hybrid Yarn ◽  
X Band ◽  
Electromagnetic Shielding Effectiveness

This study involves a comprehensive evaluation of electromagnetic shielding characteristics of multilayer three-dimensional conductive fabrics by using cotton/copper wrapped hybrid yarn in X band frequency range. Five, three-dimensional fabrics with different structural configuration, such as orthogonal, angle interlock, cellular spacer, multi-tubular spacer, and contour were produced. Three different series of all five structures was also developed using pure cotton fabric, conductive hybrid yarn in weft and one-third hybrid yarn and two-third cotton yarn in warp Also, the effect of vertical and horizontal polarization of electromagnetic waves on electromagnetic shielding effectiveness was studied. The comparative analysis of reflectance transmittance and absorption behavior was also undertaken. The results indicate that pure cotton fabric (A series) does not have electromagnetic shielding capabilities. The difference between the electromagnetic shielding effectiveness values in vertical and horizontal planes of fabrics, having conductive hybrid yarn in weft direction (B series), showed significantly better results on the vertical plane in comparison to that on the horizontal plane. Fabric containing conductive hybrid yarn in both warp and weft (C series) exhibits consistent electromagnetic shielding effectiveness in both the planes. It is worth mentioning that the structural configuration in all five three-dimensional fabrics in B and C series has shown differential trends of electromagnetic shielding effectiveness in terms of reflectance, transmittance and absorption behavior. They are also found to be statistically significant. Finally, it is concluded that the conductive 3-D multilayer system develops special protective capabilities, mostly due to its larger surface area.

Characterization of Silicone Rubber Reinforced with Conductive Powder

2011 ◽  
Vol 378-379 ◽  
pp. 535-538
Author(s):  
Elena Valentina Stoian
Keyword(s):  
Electromagnetic Field ◽  
Human Factor ◽  
Shielding Effectiveness ◽  
Micro Particles ◽  
Conductive Fillers ◽  
Transmission Measurements ◽  
Common Problems ◽  
Silicone Rubbers ◽  
Conductive Plastics

Conductive plastics are attracting more and more interest in electronics due to their light weight and inability to rust, which are common problems associated with metals. In this work silicone rubbers reinforced with conductive fillers have been fabricated for use in various applications in electronics, telecommunications, and electronics enclosures, or to protect human factor, namely protective clothing. This paper presents the results of experimental determinations concerning electromagnetic field attenuation in materials containing micro-particles of nanocarbon in their structure. To know the effect of shielding effectiveness of electromagnetic field electromagnetic absorbents were performed by transmission measurements of attenuation in the frequency range 1-18 GHz. The goal of present paper consits in the realization a composit material with polymeric matrix. The materials were characterized by transmision diminishing carried out, relative permittivity, compression test and electrical conductivity.

scholarly journals Electromagnetic Wave Shielding Effectiveness Based on Carbon Microcoil-Polyurethane Composites

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Gi-Hwan Kang ◽  
Sung-Hoon Kim
Keyword(s):  
Electromagnetic Wave ◽  
Chemical Vapor Deposition ◽  
Layer Thickness ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Thermal Chemical Vapor Deposition ◽  
Shielding Properties ◽  
Polyurethane Composites

Carbon microcoils (CMCs) were deposited onto Al2O3substrates using C2H2/H2as source gases and SF6as an incorporated additive gas in a thermal chemical vapor deposition system. CMC-polyurethane (PU) composites were obtained by dispersing the CMCs in the PU with a dimethylformamide additive. The electromagnetic wave shielding properties of the CMC-PU composites were examined in the frequency range of 0.25–1.5 GHz. The shielding effectiveness (SE) of the CMCs-PU systematically increases with increasing the content of CMCs and/or the layer thickness. Based on these results, the main SE mechanism for this work was suggested and discussed.

scholarly journals An Inexpensive Route to Synthesize High-Purity CrO2 for EMI Shielding in X-Band Frequencies

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Vivek Verma ◽  
Shahab Ahmad ◽  
Abdullah Dar ◽  
R. Kotnala
Keyword(s):  
High Purity ◽  
Microwave Frequency ◽  
External Pressure ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
X Band ◽  
Simplified Procedure

Rod-shaped high-purity samples of CrO2 have been synthesized by an inexpensive and simplified procedure. Here, we have prepared pure CrO2 without applying any external pressure or control it during synthesis. The sample prepared exhibited an improvement in saturation magnetization values, 68 emu/g at 300 K, 136 emu/g at 80 K, and uniform grained microstructure. The complex permittivity, permeability, and microwave absorption properties of high-purity CrO2 sample were investigated in the 8.2–12.2 GHz (X-band) microwave frequency range. Microwave measurements have shown the high shielding effectiveness due to absorption (SEA) of 20.3 dB. The high value of SEA suggests that CrO2 can be used as a promising electromagnetic shielding, EMI, material in 8.2–12.2 GHz (X-band) microwave frequency range.

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