Composite Electromagnetic Wave Absorber Made of Both Sendust and Aluminum Particles Dispersed in Polystyrene Resin

2010 ◽  
Vol 445 ◽  
pp. 197-200
Author(s):  
Kenji Sakai ◽  
Yang Guan ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Particle Size ◽  
Electromagnetic Wave ◽  
Return Loss ◽  
Complex Permeability ◽  
Frequency Range ◽  
Aluminum Particles ◽  
Absorption Properties ◽  
Mixture Ratio ◽  
Polystyrene Resin ◽  
Frequency Dependences

To design an electromagnetic wave absorber with good absorption properties at frequencies above 1 GHz, the frequency dependences of the relative complex permeability μr*, the relative complex permittivity εr*, and return loss were investigated for the composite made of both sendust (an alloy of Al 5%, Si 10%, and Fe 85%) and aluminum particles dispersed in polystyrene resin. It was found that the frequency dependence of μr* for this composite can be changed by adjusting the particle size of aluminum and the volume mixture ratio of sendust and aluminum. Therefore, a flexible design of an absorber with good absorption characteristics was proposed based on the ability to control μr*. The composite made of both sendust and aluminum was found to exhibit a return loss of less than −20 dB in the frequency range of not only several GHz but also around 20 GHz if appropriate volume mixture ratio and particle size were selected.

Evaluation of Composite Electromagnetic Wave Absorber made of Polystyrene Resin and Permalloy or Sendust

2007 ◽  
Vol 350 ◽  
pp. 239-242 ◽  
Author(s):  
Kenji Sakai ◽  
Shinzo Yoshikado
Keyword(s):  
Electromagnetic Wave ◽  
Magnetic Materials ◽  
Electromagnetic Waves ◽  
Return Loss ◽  
Soft Magnetic Materials ◽  
Complex Permeability ◽  
Soft Magnetic ◽  
Mixture Ratio ◽  
Polystyrene Resin ◽  
Frequency Dependences

The frequency dependences of the complex permeability μ r*, complex permittivity ε r*, and return loss were investigated for composite electromagnetic wave absorbers made of soft magnetic materials (permalloy or sendust) and polystyrene resin. For permalloy, two types of particle shape were used: grain-type or flake-type. The volume mixture ratio of magnetic materials was varied in the range from 40 % to 70 %. The values of the real part μ ’ and imaginary part μ ” of μ r * increased with increasing mixture ratio of magnetic materials. The frequency dependence of μ r * for flake-type permalloy composite was similar to that for sendust composite. All absorbers showed the absorption of electromagnetic waves in the frequency range above 1 GHz.

Effect of Sendust Particle Size on Absorption Characteristics of Composite Electromagnetic Wave Absorber

2009 ◽  
Vol 421-422 ◽  
pp. 451-454
Author(s):  
Kenji Sakai ◽  
Yoichi Wada ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Particle Size ◽  
Electromagnetic Wave ◽  
Return Loss ◽  
Single Layer ◽  
Complex Permeability ◽  
Wave Power ◽  
Flexible Design ◽  
Frequency Range ◽  
Polystyrene Resin ◽  
Absorption Characteristics

The effects of the particle size of sendust, which is an alloy of Al 5%, Si 10%, and Fe 85%, on the absorption characteristics of composite electromagnetic wave absorbers made of polystyrene resin and sendust were investigated in the frequency range from 1 to 40 GHz. The size of sendust particles was varied between approximately 5 and 20 m. A metal-backed single-layer absorber made of 20 m sendust particles absorbed more than 99% of electromagnetic wave power at frequencies above 20 GHz. Meanwhile, a composite made of 5 m particles exhibited a return loss of less than −20 dB in the frequency range of not only several GHz but also above 30 GHz. In addition, the relative complex permeability r* was shown to be controlled by adjusting the particle size of sendust, and an electromagnetic wave absorber with a flexible design was proposed.

Design of Composite Electromagnetic Wave Absorber Made of Soft Magnetic Materials Dispersed and Isolated in Polystyrene Resin

2008 ◽  
Vol 388 ◽  
pp. 257-260 ◽  
Author(s):  
Kenji Sakai ◽  
Yoichi Wada ◽  
Shinzo Yoshikado
Keyword(s):  
Magnetic Material ◽  
Electromagnetic Wave ◽  
Magnetic Materials ◽  
Soft Magnetic Materials ◽  
Soft Magnetic Material ◽  
Complex Permeability ◽  
Frequency Range ◽  
Soft Magnetic ◽  
Mixture Ratio ◽  
Polystyrene Resin

Composite electromagnetic wave absorbers made of a soft magnetic material (permalloy or sendust) and polystyrene resin were investigated [1]. The volume mixture ratio of magnetic material was varied in the range from 18 vol% to 75 vol%. The composites with the low volume mixture ratio of soft magnetic material absorbed more than 99 % of electromagnetic wave power in the frequency range from 1 GHz to 10 GHz. The values of the real part r’ of the relative complex permeability r * for both magnetic materials were less than unity at frequencies above approximately 6 GHz as the volume mixture ratio of magnetic material increased. This result suggests the possible realization of an electromagnetic wave absorber that can operate above 10 GHz.

Composite Electromagnetic Wave Absorber Made of Ni-Zn Ferrite Particles Dispersed and Isolated in an SiO2 Medium

2011 ◽  
Vol 485 ◽  
pp. 229-232
Author(s):  
Kenji Sakai ◽  
Yang Guan ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Electromagnetic Wave ◽  
Frequency Dependence ◽  
Complex Permittivity ◽  
Return Loss ◽  
Complex Permeability ◽  
Mixture Ratio ◽  
Zn Ferrite ◽  
Frequency Dependences ◽  
Absorption Characteristics

In order to design a ferrite absorber that can be used at frequencies of several GHz, the frequency dependences of the relative complex permeability μr*, the relative complex permittivity εr*, and return loss were investigated for a composite made of Ni-Zn ferrite and SiO2. When ferrite particles were dispersed and isolated in an SiO2 medium, the frequency dependence of μr* was different from that for a composite made of SiO2 particles dispersed and isolated in the ferrite medium. Moreover, when ferrite particles were isolated and a suitable mixture ratio of ferrite and SiO2 was selected, the return loss was less than −20 dB at frequencies of several GHz. The dispersion states of ferrite and SiO2 particles are thus important factors to design an absorber, and improvement in the absorption characteristics of the ferrite tile which is used as a practical absorber could be achieved using a composite made of Ni-Zn ferrite particles dispersed and isolated in an SiO2 medium.

Particle Size Effects on Complex Permeability and Electromagnetic Wave Absorption Properties of Amorphous Alloy-Epoxy Composites

2007 ◽  
Vol 539-543 ◽  
pp. 1022-1027
Author(s):  
Kyoung Mook Lim ◽  
Moon Chul Kim ◽  
Chan Gyung Park ◽  
Y.M. Hong
Keyword(s):  
Particle Size ◽  
Electromagnetic Wave ◽  
Amorphous Alloy ◽  
Magnetic Relaxation ◽  
Epoxy Composites ◽  
Complex Permeability ◽  
Frequency Variation ◽  
Absorption Properties ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption

The electromagnetic wave absorption properties of amorphous alloy-epoxy composites have been investigated utilizing various amorphous alloy particle sizes in quasi-microwave frequency. The composite fabricated with small sized particle (< 26 μm) only revealed good absorption properties above 20dB with a thin thickness less than 6 mm. As particle size decreased, absorber had thinner matching thickness mainly due to increasing matching frequency. Such a variation of matching frequency was resulted from resonance frequency variation. The magnetic relaxation of the composites with small particle (< 38 μm) was contributed to magnetic resonance induced by demagnetization field. The eddy current also affected on the magnetic relaxation of the composites with large particle (> 38 μm) due to their large conductivity.

Magnetization and Microwave Absorption Properties of La0.67 Sr0.33 MnO3 with Different Particle Size

2011 ◽  
Vol 374-377 ◽  
pp. 1541-1544 ◽  
Author(s):  
Yu Lan Cheng ◽  
Ping Xia ◽  
Ke Xiang Wei ◽  
Quan Bai
Keyword(s):  
Particle Size ◽  
Sinter Temperature ◽  
Microwave Absorption ◽  
Reflection Loss ◽  
Sol Gel ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Measured Frequency Range ◽  
Maximum Reflection Loss

La 0.67 Sr 0.33 MnO 3 particles with different particle size have been prepared by sol-gel method. The structure, magnetization and microwave absorption properties have been investigated. The results show that the particle size can be controlled by sinter temperature. The peaks of the maximum reflection loss (RL) move to higher frequency regions with increasing particle size. The value of the maximum RL is -32 dB at 10.2GHz with a particle size of 58.5nm. The bandwidth with a RL exceeding -8dB reached 1.6GHz in the whole measured frequency range, suggesting that La 0.67 Sr 0.33 MnO 3 particles are promising for application as a wideband and strong absorption building microwave absorber.

Fabrication of Flaky Magnetic Composite Particles

2012 ◽  
Vol 490-495 ◽  
pp. 2628-2631
Author(s):  
Wen Qiang Zhang
Keyword(s):  
Vapor Deposition ◽  
Broad Band ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Complex Permeability ◽  
Composite Particles ◽  
Magnetic Composite ◽  
Frequency Range ◽  
Absorption Properties ◽  
Microwave Absorption Properties

Diatomite coated with ɑ-Fe films were obtained by Chemical Vapor Deposition process. The resultant Fe-coated flaky diatomite particles had low densities. The results show that Fe coated diatomite flakes can be achieved, and that the coating consisted of ɑ-Fe nano-crystallite. The complex permeability and permittivity of the composites were measured in the frequency range of 1–18 GHz. The microwave absorption properties of these flaky particles are discussed. The results indicate that the flaky particles have potential to be used as a lightweight broad band microwave absorber.

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