• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.330-334
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• 2006

In this research, we fabricated paint-type EM wave absorbers by using Mn-Zn, Ni-Zn, Ba, Sr Ferrite, and Sendust. To prepare the absorbers, enamel, epoxy and urethane paints were used as binders. We tested EM wave absorption of them. The band-width of EM wave absorbers coated with $Al(OH)_3$ was larger than non-coated EM wave absorbers. The fabricated EM wave absorbers show a reflection coefficient of 20 dB approximately at X-band for a 2 mm double-layer sample.

• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.114-117
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• 2006

In this paper, we fabricated the EM wave absorber for 94 GHz radar sensors using Permalloy of magnetic material with chlorinated polyethylene (CPE), and S-parameter was measured. The complex relative permittivity and permeability are calculated by the measured data. Absorption abilities are simulated according to different thickness of the EM wave absorbers, and the EM wave absorber was manufactured based on the simulated design. Simulated and measured results agree very well. As a result, we developed the EM wave absorber with the thickness of 1.15 mm which has an absorption ability of 18 dB at 94 GHz.

• Advances in concrete construction
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• v.3 no.2
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• pp.103-111
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• 2015

The foam concrete was fabricated by adding the foaming agent which composite ordinary Portland cement with plant and animal protein into cement paste, and the electromagnetic wave absorption properties were studied for the first time as well. The studies showed that the electromagnetic waves can be absorbed by multiple reflections and scattering within the porous material. Thickness and filling ratio have a great influence on the electromagnetic wave absorbing properties in 2-18 GHz of the foam concrete, the greater the thickness, the better the performance of absorption; filling ratio was about 52 vol.%, the absorbing properties achieved the best.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.86-89
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• 2001

In this paper, the composite damping sheet with electromagnetic wave absorption was developed and studied. The damping sheets with Ni-Zn ferrite, Mn-Zn ferrite and PZT were prepared by mixing, molding and drying. From the characterizing results, the optimal portion of the composite is 1:1:0.1 of Mn-Zn ferrite:Rubber:PZT. The maximum absorption was -30 dB at 860 MHz in the single structure and over -15 dB at 180 MHz and 860 MHz in the two or three layers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.562-569
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• 2009

Recently, Hi-pass system(non-stop electric toll collection) using DSRC is working. However, it has various problems such as system errors by EM wave interference or multi-path reflection. The EM wave absorber is able to solve these problems. In this paper, we designed and fabricated EM wave absorber using amorphous substance. As a result EM wave absorber with composition of amorphous metal powder:CPE=45:55 wt.% has the thickness of 2.65 mm and absorption ability was higher than 40 dB at 5.8 GHz.

• Journal of Navigation and Port Research
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• v.34 no.2
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• pp.111-115
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• 2010

In this paper, the electromagnetic (EM) wave absorbers using TiO2 as a dielectric material with chlorinated polyethylene (CPE) were investigated in W-band radio frequencies. We compared the relative permittivity with reflectionless curve and the absorption properties of samples containing 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, and 80 wt.% TiO2. It is possible to realize a complex relative permittivity satisfying the reflectionless condition by choosing composition ratio of TiO2. The optimized composition ratio of TiO2 for the maximum absorption property is about 70 wt.%. As a result, we have confirmed the realization of an EM wave absorber with a high absorption property in W-band radio frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.270-274
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• 2019

In this paper, we analyze a planar electromagnetic absorber by using the mode matching technique(MMT). The proposed electromagnetic absorber has a periodic structure composed of a perfect conductor and ferrite, and the transmitted and reflected powers in response to the incident wave with parallel polarization are calculated according to the thickness of the plate. The proposed absorber shows a high absorption compared to the cases of periodic slits with vacuum or the ferrite plate itself. The solution to the reflected and transmitted powers by MMT is also verified with the results from a commercial simulator.

• Journal of the Korean Magnetics Society
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• v.22 no.6
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• pp.210-215
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• 2012

The absorption performance of a metal-backed single layered electromagnetic wave absorber is optimized at matching conditions of thickness and frequency indicating the maximum returns loss of incidence electromagnetic wave in the contour map. These matching conditions are obtained by applying the electromagnetic impedance to the transmission line theory, which depend on the complex permeability and complex permittivity of absorber material. The magnetic materials with high permeability can enhance the matching thickness condition to the wide frequency range based on the decrease of permeability with frequency and it can be used as a wideband electromagnetic wave absorber material. Therefore, the magnetic materials with higher saturation magnetization and lower permittivity than NiZn ferrite can be applied to the wideband electromagnetic wave absorber in order to satisfy the newly enforcing the electromagnetic compatibility regulation in the future.

• Journal of Powder Materials
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• v.14 no.4
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• pp.265-271
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• 2007

Electromagnetic wave absorbing materials have been developed to reduce electromagnetic interference (EMI) for electronic devices in recent years. In this study, Fe-Si-B-Nb-Cu base amorphous strip was pulverized using a jet mill and an attritor and heat-treated to get flake-shaped nanocrystalline powders, and then the powders were mixed, cast and dried with dielectric $Al_{2}O_{3}$ powders and binders. As a result, the addition of $Al_{2}O_{3}$ powders improved the absorbing properties of the sheets noticeably compared with those of the sheets without dielectric materials. The sheet mixed with 2 wt% $Al_{2}O_{3}$ powder showed the best electromagnetic wave absorption, which was caused by the increase of the permittivity and the electric resistance due to the dielectric materials finely dispersed on the Fe-based powder.

• Journal of Powder Materials
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• v.15 no.1
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• pp.53-57
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• 2008

The amorphous $Fe_{73}Si_{16}B_7Nb_3Cu_1$(at%) alloy strip was pulverized using a jet mill and an attrition mill to get flake-shaped powder. The flake powder was mixed with dielectric $BaTiO_3$ powder and its dispersant to increase the permittivity. The powders covered with dielectric powders and its dispersant were mixed with a binder and a solvent and then tape-cast to form sheets. The absorbing properties of the sheets were measured to investigate the roles of the dielectric powder and its dispersant. The results showed that the addition of $BaTiO_3$ powders and its dispersant improved the absorbing properties of the sheets noticeably. The powder sheet mixed with 5 wt% of $BaTiO_3$ powder and 1 wt% of dispersant showed the best electromagnetic wave absorption rate because of the increase of the permittivity and the electrical resistance.