• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.1051-1057
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• 2008

In this paper, we analyzed the characteristics of the EM wave absorber which was fabricated by using flake sendust (soft metal magnetic powder). The flake sendust was made of 3 different granularity by attrition mill. First, we have fabricated 3 kind of EM wave absorbers using the flake sendust and CPE(Chlorinated Polyethylene) and measured the S-parameters of the EM wave absorber. The complex relative permittivity and permeability were calculated from the measured data and the variations according to a change of granularity were researched. As a result, it was confirmed that the EM wave absorber using flake sendust with the $140{\mu}m$ average granularity has outstanding absorption ability in high frequency range(C band) for the reduction of eddy current loss(increase of permeability) and the increase of space charge polarization(increase of permittivity).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.159-160
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• 2010

In this paper, we compared the absorption abilities of AMP and Sendust EM wave absorbers for a port logistics RFID system. Firstly, we fabricated EM wave absorber samples by using each absorbing material, AMP or Sendust, and CPE (Chlorinated Polyethylene) with composition ratios 85 : 15 wt. %. Secondly, we designed the optimum EM wave absorber using the calculated material constants found from the measured input impedance of the samples. Therefore, we confirmed that imaginary factor of complex relative permeability influences absorption ability and that AMP is better absorbing material than Sendust at the frequency band of 433 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.244-249
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• 2008

In this paper, we designed and fabricated the EM wave absorber consists of Sendust and Mn-Zn ferrite for suppressing EM wave noise from PCB in ISM(Industrial, Scientific and Medical) band of 2.4 GHz. We fabricated several samples in different ratios of Sendust to Mn-Zn ferrite with CPE(Chlorinated Ploy-ethylene) as binder and confirmed that optimum composition ratio of absorbing materials was Sendust. Mn-Zn ferrite : CPE=70:5:20 wt.%. The absorbing abilities were simulated according to different thickness of EM wave absorber as the function of material constants calculated by measured data. Measured absorption ability was analyzed and compared with simulated result. The simulated result agree well with the measured ones. As a result, the developed EM wave absorber with thickness of 0.85 mm has absorption ability of 5.4 dB at 2.4 GHz and over 3 dB in frequency rage of 1.4$\sim$4.1 GHz.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.97-101
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• 2006

In this paper, Multi-layer EM wave absorbers using Sendust are presented. The bandwidth of the Multi-layer Sendust EM wave absorbers over 10 dB is extended in S-Band And we investigated the mixing effects of $Al(OH)_3$ on Multi-layer Sendust EM wave Absorbers. As a result, the Multi-layer Sendust EM wave absorbers mixed with $Al(OH)_3$ showed a extended bandwidth over 10 dB compared with non-mixed Multi-layer Sendust EM wave absorbers in S-Band.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.13-15
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• 2010

본 논문에서는 Flake Sendust 금속분말을 이용하여 ISM 대역에서 PCB 노이즈 억제용 전파흡수체를 설계 제작하고 검토한 결과를 보고한다. 먼저 자성손실 재료인 Sendust 금속분말을 사용한 전파흡수체의 특성을 예비 시험한 후, 그 특성을 개선하기 위하여 Flake Sendust 분말과 CPE의 조성비를 각각 60 : 40 wt.%, 70 : 30 wt.%, 80 : 20 wt.%로 하고, 두께 1 mm, 2 mm의 sheet형 전파흡수체 샘플을 제작하였다. Network Analyzer를 이용하여 제작한 샘플의 반사계수를 측정하고, -2법으로 재료정수(복소비유전율, 복소비투자율)을 계산하였다. 계산된 재료정수값을 이용하여 최적의 전파흡수체를 설계하여, 조성비 Flake Sendust : CPE = 70 : 30 wt.%, 두께 0.55 mm의 전파흡수체를 제작하였다. 이 전파흡수체는 2.44 GHz 대역에서 5.45 dB의 흡수능을 나타냄으로써 목표치인 5 dB를 달성하였다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.429-434
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• 2005

In this paper, we investigated EM wave absorption property of EM wave absorbers prepared with sendust. The EM wave absorbers have good EM wave absorption properties in 1 GHz ${\sim}$ 3 GHz. On the other hand, the absorption band of the EM wave absorber coated with $Al(OH)_3$ larger than non-coated one. Pulverization effect of sendust on EM wave absorption properties was also investigated.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.637-642
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• 2006

In this paper, we made an experiment on materials of two kinds. First, we made a study of Multi-layer EM wave absorbers using Sendust. In result, The bandwidth of the Multi-layer Sendust EM wave absorbers over 10 dB is extended in S-Band. Second, we investigated the mixing effects of AI(OH)3 on Multi-layer Sendust EM wave Absorbers. In result, the Multi-layer Sendust EM wave absorbers mixed with Al(OH)3 showed a extended bandwidth over 10 dB compared with non-mixed Multi-layer Sendust EM wave absorbers in S-Band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.423-429
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• 2006

This paper deals with research for development of electromagnetic wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, and the milling time, electromagnetic wave absorbers were prepared and examined. Central frequency shills toward lower 2.2 GHz, 1.29 GHz, 842 MHz with increasing thickness 1 mm, 2 mm, 3 mm of the absorber, and absorption ability controlled each 2.2 GHz to 1.91 GHz, 1.29 GHz to 801 MHz, 842 MH2 to 801 MHz adjust sendust amount from 80 wt% to 85 wt%. The absorption band of the electromagnetic wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated electromagnetic wave absorbers show a reflection coefficient 5.76 dB at 1.8 GHz in thickness of 0.85 mm.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.67-68
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• 2005

This thesis is concerned with basic research for development of EM wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, EM wave absorbers were prepared and examined. Centeral frequency shifts toward lower with increasing thickness of the absorber, and absorption ability controlled to adjust Sendust amount. The absorption band of the EM wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated EM wave absorbers show a reflection coefficient 5.56 dB at 1.8 GHz in thickness of 0.85 mm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1136-1141
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• 2007

In this paper, we designed and fabricated EM wave absorbers using Sendust, $Al(OH)_3$ and CPE(Chlorinated Polyethylene). We compared the absorption properties of samples containing 0 wt.%, 3 wt.%, 5 wt.%, 7 wt.% of $Al(OH)_3$. The optimized composition ratio of $Al(OH)_3$ is 5 wt.%, and the absorption property curve just has the tendency to improve at 5 wt.% of $Al(OH)_3$. And we used this characteristics to design the double-layered EM wave absorber. The double-layered EM wave absorber has thickness of 2 mm and has absorption ability more than 18.5 dB at a wireless LAN frequency band using 2.4 GHz.