• Journal of the Korean Institute of Navigation
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• v.23 no.1
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• pp.15-22
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• 1999

In this paper, ferrite-rubber composite has been studied in order to apply to RF-A-PF in a super wideband electromagnetic absorber in RF-A-PF type, which can be used for a general purpose anechoic chamber. $Ni_x - Mn_0.1 - Zn_{(1-x-0.1)}ㆍFe_2O_4$ ferrite powder has been fabricated, then, using this, 〔$Ni_x - Mn_0.1 - Zn_{(1-x-0.1)}ㆍFe_2O_4$〕-Rubber composite for RF-layer in the RF-A-PF type absorber has been fabricated and it's characteristics have been analyzed. As a result, it has been clearly shown that the 〔$Ni_x - Mn_0.1 - Zn_{(1-x-0.1)}ㆍFe_2O_4$〕-Rubber composite has excellent electromagnetic wave absorbing properties.

• Journal of the Korean Ceramic Society
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• v.28 no.8
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• pp.640-646
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• 1991

Recently intensive studies have been focussed on ferrites which have high magnetic loss because of the increasing need for the prevention of EMI (Electromagnetic Interference). We investigated effects of microstructures of Ni-Zn ferrites on magnetic losses, magnetic properties, and behaviors of electromagnetic wave absorbers. The characteristics of the absorber were influenced by the sintering conditions. A Ni-Zn ferrite with the thickness of 7$^{\circ}C$/min and the cooling rate of 7$^{\circ}C$/min. It satisfied the absorbing properties in the wide frequency ranges including VHF (90∼220 MHz), UHF (470∼770 MHz)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.35-42
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• 1999

This paper describes the characteristics of the complex isotropic ferrite-rubber composite for a super wideband electromagnetic absorber in RP-A-PF type, which can be used for an anechoic chamber, wall material to prevent TV ghost, etc. The $Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$ ferrite powder has been fabricated. Using this, then, [$Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$]-Rubber composite for RF-layer in the RF-A-PF type absorber has been fabricated and it's characteristics has been analyzed. As a result, it has been shown that the [$Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$].Rubber composite has excellent electromagnetic wave absorbing properties.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.346-352
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• 1996

A wide-band design method of double layered electromagnetic wave absorbers cross-slotted in the second layer(which has very wide band frequency characteristics) is proposed and discussed. The wide-band electromagnetic wave absorber can be designed under some approximations by the the- oretical model using the equivalent material constants method applied to the second layer. Based on the developed model, wide-band electromagnetic wave absorbers with excellent reflectivity characteristics in the frequency range of 30MHz to 3, 170MHz were designed.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.161-165
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• 2005

We prepared Mn-Zn ferrite Electromagnetic(EM) wave absorbers. The Mn-Zn ferrite EM wave absorbers were coated with Sr ferrite powders and $Al(OH)_3$ powders. The coated Mn-Zn ferrite EM wave absorbers show improved absorption compared with non-coated Mn-Zn EM wave absorbers.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.3-10
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• 1993

As a method to measure the absorbing characteristics of microwave absorber, various microwave measuring method can be used fundamentally. There is, however, a big problem in measuring errors, since the wavelength of microwave such as used for radar is very short. Therefor, this research aimed to design and fabricate a converting adaptor of 20mm .PHI. coaxial tube from a type-N connector to coaxial tube and to use it for evaluating absorption characteristics of microwave absorbor. Furthemore, the measurements of absorbing characteristics and material constants have been perfomed and reviewed, which were carried out by using the coaxial and by using rectangular waveguide, respectively. As a result, the validity of the proposed measuring method has been conformed. In this paper, a preliminary evalua- tion on the characteristics of the electromagnetic wave absorbor for X-band radar designed and fabricated for a laboratory use is performed by reflected power method near to a pratical use. Then for field test by using X-band radar is carried out with real target of $1.2m\times1.2m$ in size. As the result of the above, the usefullness of the designed and fabricated electromagnetic wave absorber in paint type for X-band radar has been confirmed.

• Proceedings of the Korean Magnestics Society Conference
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• 1991.05a
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• pp.63-64
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• 1991

• Proceedings of the Korean Magnestics Society Conference
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• 1991.11a
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• pp.56-57
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• 1991

• Proceedings of the Korean Magnestics Society Conference
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• 1991.11a
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• pp.58-59
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• 1991

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.23-27
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• 2004

Developing of electromagnetic wave absorbers for GHz frequency, we used cast Alnico magnets. It is the first research paper to show that electromagnetic wave absorbers with Alnico magnets have good reflectivity in the GHz frequencies. Especially in this study, we used recycled cast Alnico magnets for natural resources problems and natural environment problems. New electromagnetic wave absorbers developed in this study are useful for X-band and C-band.