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.

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.

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.

Study and characterization of E.M. absorbing properties of EPDM ferrite composite containing manganese zinc ferrite

2017 ◽  
Vol 36 (10) ◽  
pp. 754-765 ◽  
Author(s):  
Mohit Katiyar ◽  
Mahender Prasad ◽  
Kavita Agarwal ◽  
RK Singh ◽  
Anand Kumar ◽  
...  
Keyword(s):  
Zinc Ferrite ◽  
Single Layer ◽  
Ferrite Content ◽  
Complex Permeability ◽  
Frequency Range ◽  
Manganese Zinc ◽  
Manganese Zinc Ferrite ◽  
Zn Ferrite ◽  
Ferrite Composites ◽  
Rubber Ferrite Composites

EPDM rubber has been used as matrix and manganese–zinc ferrite as magnetic filler. EPDM ferrite composites were prepared with varying loading in different compositions of Mn–Zn ferrite (RFC-1, 2, 3 and 4) and moulded in the test samples of different thicknesses i.e. 1.5 mm, 2.5 mm and 5 mm. Physico-mechanical properties of EPDM ferrite composites were determined. Complex permeability and permittivity parameters of rubber ferrite composites were measured using rectangular waveguide in the frequency range of 3.95–5.85 GHz. The variation of reflection loss (RL) of single layer rubber-ferrite composites has been investigated as a function of frequency, ferrite content and thickness of composites by unique single horn interferometry technique in the frequency range of 2–18 GHz. It is observed that microwave absorption of rubber–ferrite composites has increased with increase of ferrite content as well as thickness in the frequency range of 2–18 GHz.

Absorption Characteristics of Composite Electromagnetic Wave Absorber Made of Sendust Particles Dispersed in Polystyrene Resin

2013 ◽  
Vol 566 ◽  
pp. 215-218
Author(s):  
Yuki Hongo ◽  
Kenji Sakai ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Electromagnetic Wave ◽  
Low Cost ◽  
Volume Ratio ◽  
Average Particle ◽  
Particle Sizes ◽  
Frequency Bandwidth ◽  
Rare Metals ◽  
Absorption Frequency ◽  
Polystyrene Resin ◽  
Absorption Characteristics

A low-cost composite electromagnetic wave absorber made of sendust dispersed in resin was developed that does not contain any rare metals. In this study, spherical sendust particles with average particle sizes of approximately 5 and 20 μm were dispersed in polystyrene resin at volume ratios in the range 2040 vol% to broaden the absorption frequency bandwidth at frequencies above 10 GHz. The optimal volume ratios of sendust with average particle sizes of approximately 5 and 20 μm were found to be approximately 30 and 35 vol%, respectively. Electromagnetic wave absorbers can be flexibly designed by controlling the volume ratio of spherical sendust particles in resin.

Sign in / Sign up

Export Citation Format

Share Document