• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.2
• /
• pp.59-65
• /
• 2019

The EMI shielding effectiveness of shielding layers thickness was analyzed when the low conductivity shielding layers was placed in the near field of the noise source. A spiral antenna with broadband characteristics was used as the noise source, and graphite was selected as the low conductivity shielding material. Two spiral antennas were constructed to analyze the transmission coefficient between two antennas, and the distances between the transmitting and receiving antennas were 5 cm and 10 cm. The thickness of the shielding layers was changed from 1 um to 200 um. The frequency was changed from 100 MHz to 6 GHz to obtain a maximum SE(Shielding Effectiveness) of 70 dB. In this simulation, electronic shielding was used due to the nature of graphite, which is a shielding film material. Based on these results, we will study how to improve the shielding performance by implementing magnetic shielding in the future.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.4
• /
• pp.10-16
• /
• 2008

This study investigated electromagnetic interference(EMI) shielding effectiveness(SE) of the aluminum film, conductive fabric and nano carbon black carbon fiber reinforced composites. We fabricated carbon fiber reinforced composites filled with nano carbon black where they bonded aluminum film and conductive fabric. The measurements of SE were carried out frequency range from 300MHz to 1.5GHz. It is observed that the SE of the bonded aluminum film and conductive fabric composites is the frequency dependent, increase with the increase in filler nano carbon black content. The aluminum film bonded composites showed higher SE compared to that of carbon black and conductive fabric. The aluminum film bonded epoxy composite was shown to exhibit up to 80dB of SE. The result that aluminum film bonded composite can be used for the purpose of EMI shielding as well as for some microwave applications.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.8 s.185
• /
• pp.100-107
• /
• 2006

The objective of this research is to investigate the electromagnetic interference(EMI) shielding characteristics of fiber reinforced composites. We fabricated glass and carbon fiber reinforced composites filled with metal powder and nano carbon black. The measurements of shielding effectiveness(SE) were carried out frequency range 300MHz - 1GHz for commercial purposes such as electric or telecommunication devices. The return loss and loss due to absorption were also measured as a function of frequency in the micro wave(300MHz-1GHz) region. It is observed that the SE of the composites is the frequency dependent, increase with the increases in filler loading. The Mg metal powder filled composite showed higher SE compared to that of carbon black. The Mg metal powder/epoxy composite was shown to exhibit up to 40dB of SE. The results indicates that the composite having higher filler loading can be used for the purpose of EMI shielding as well as for some microwave applications.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.3
• /
• pp.59-65
• /
• 2019

The EMI shielding effectiveness of the shielding layer thickness was analyzed when the metal shielding layer was placed in the near field of the magnetic probe and the noise source. Microstrip lines were used as noise source, and graphite and ferrite were selected as metal shielding materials. The magnetic probe uses the electromagnetic radiation measurement method using the magnetic probe by applying the IEC 61967-6 method. The transmission coefficient between the microstrip line and the magnetic probe was analyzed. The distance between the two was 1 mm for a single shielding layer and 5 mm for a multiple shielding layer. The thickness of the shielding layer was changed to 5 um, 10 um, 30 um, and 50 um. When the frequency was changed from 150 kHz to 1 GHz, a maximum shielding effectiveness (SE) of 44.9 dB was obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.3
• /
• pp.254-263
• /
• 1997

As the communication and electronic industry develops, it is important to study the electromagnetic shielding effectiveness (SE) of carbon fiber (CF) reinforced thermal plastics (CFRTP) against the electromagnetic (EM) radiation. In this paper the shielding effectiveness of CFRTP was measured experimentally in an electromagnetic shielding room. The resin ma- terials used were PC, PP, PEI, PMMA and PA. Experiments were carried out by using a copper box and a monopole antenna with a spectrum analyzer. From the experimental results it was found that CF was a good candidate as an electromagnetic shielding material. The sheilding effectiveness was found to be increased in the composite as the number of laminated layers of CF was increased. As the minor damage increased, the SE increased due to increasing of the plane density, transmitting thickness and reflected angle of the CF. Other characteristics of the SE depended on the material used for the resin matrix, distance of the antennas and the noise frequency band.

• Carbon letters
• /
• v.22
• /
• pp.36-41
• /
• 2017

Biodegradable epoxy (B-epoxy) was prepared from diglycidyl ether of bisphenol A and epoxidized linseed oil. The mechanical properties of B-epoxy composites reinforced with multi-walled carbon nanotubes (MWCNTs/B-epoxy) were examined by employing dynamic mechanical analysis, critical stress intensity factor ($K_{IC}$) tests, and impact strength tests. The electromagnetic interference shielding effectiveness (EMI-SE) of the composites was evaluated using reflection and absorption methods. Mechanical properties of MWCNTs/B-epoxy were enhanced with an increase in the MWCNT content, whereas they deteriorated when the MWCNT content was >5 parts per hundred resin (phr). This can likely be attributed to the entanglement of MWCNTs with each other in the B-epoxy due to the presence of an excess amount of MWCNTs. The highest EMI-SE obtained was ~16 dB for the MWCNTs/B-epoxy composites with a MWCNT content of 13 phr at 1.4 GHz. The composites (13 phr) exhibited the minimum EMI-SE (90%) when used as shielding materials at 1.4 GHz. The EMI-SE of the MWCNTs/B-epoxy also increased with an increase in the MWCNT content, which is a key factor affecting the EMI-SE.

• Textile Coloration and Finishing
• /
• v.16 no.5
• /
• pp.42-47
• /
• 2004

The main objective of this work is to develop melt-blown nonwoven fabric composite materials have electromagnetic shielding characteristics using thin copper film. Melt-blown nonwoven fabric is the matrix phase and thin copper films are the reinforcement of the composite materials. Thin copper films are incorporated as conductive fillers to provide the electromagnetic shielding property of the melt-blown nonwoven fabric. The width and interval of thin copper films in the nonwoven fabric are varied by changing 1, 3, 5 mm for thin copper film's width and 1, 3, 5 mm for thin copper film's interval. The shielding effectiveness(SE) of various melt-blown nonwoven fabrics is measured in the frequency range of 50 MHz to 1.8 GHz. The variations of SE of melt-blown nonwoven fabric with width and interval of thin copper films are described. Suitability of melt-blown nonwoven fabric for electromagnetic shielding applications is discussed. The results indicate that the melt-blown nonwoven fabric composite material using thin copper film can be used for the purpose of electromagnetic shielding.

• Journal of the Korean Society of Safety
• /
• v.19 no.4 s.68
• /
• pp.80-85
• /
• 2004

Electromagnetic interference(EMI) shielding characteristics of composite filled with Cu flake and carbon brush powder as hybrid conductive filler and EAF slag have been studied. The coaxial transmission line method of ASTM D4935-99 was used to measure the EMI Shielding effectiveness of composites as formulation in frequency rage $100\~1,000MHz$ The SE also increases with the increase in flier loading. The hybrid filler filled composites show higher SE compared to that of only Cu flake. The correlation between SE and conductivity of the various composites is also discussed. The results indicate that the composites having higher filler loading$({\geq}40wt.\%)$ can be used for the purpose of safety materials to protect hazardous electromagnetic interference.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.47-53
• /
• 2003

Screen filter of PDP TV plays an important role in satisfying the EMI/EMC specifications. Two types of filters, the mesh type and the sputter type, are used in PDP TVs, and this paper presents measurement results of the shielding effectiveness (SE) in the frequency range from 50MHz to 1GHz. Two methods were used for the measurement, one using network analyzer (NA) in an open area test site(OATS), and the other using the screen room. The overall conclusion is that the shielding effectiveness of the screen filter is related to the surface resistance of the screen filter. The mesh type screen filters are superior to the sputter types in the shielding effectiveness, which is varying with the frequency.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.6
• /
• pp.1121-1128
• /
• 2011

The HEMP has very short rising time with several tens of kV/m, and very dangerous to almost of the electronics. And the certain level of EMP shielding effectiveness is necessary for mos t of the systems andequipment. In EMP shielding effectiveness, the peak value and the rising time in the system are the most considerable parameters. In order to find out these parameters, we need to estimate the pulse shape in time domain. In this paper, we propose the methods to estimate the penetrated pulse in time domain using measured shielding effectiveness and digital filter modeling technique. The validity of the Digital filter modeling technique is verified by the HFSS.