Woody electric wave absorber

A radio wave absorbing material, wood technology, applied in the direction of magnetic material, inorganic material magnetism, circuit, etc., can solve the problem of less degree of freedom, and achieve the effect of improving the degree of freedom of design and superior radio wave absorption characteristics

Inactive Publication Date: 2007-01-31
JAPAN SCI & TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0023] As a radio wave absorbing material corresponding to the GHz frequency band that absorbs these unnecessary radio waves, various radio wave absorbing materials of the above-mentioned conventional technology have been de...

Method used

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  • Woody electric wave absorber
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  • Woody electric wave absorber

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] When the total volume content of ferrite powder and stainless steel powder Vs = 20vol%, the ratio (volume) of the two is the ratio shown in Table 2 and vinyl acetate resin latex adhesive (adhesive for woodworking) ) mixed and clamped on - two fiberboards with a thickness of 2.5mm (specific gravity 0.9g / cm 3 ) was allowed to dry for about 96 hours to prepare laminated magnetic wood samples. The thickness of the magnetic layer was 4.0 mm.

[0057]

[0058] stainless steel only

[0059] image 3 (A), (B) are the measurement results showing the radio wave absorption in the range of measurement frequency 0.05-12 GHz. Depend on image 3 , in the magnetic layer dm = 4.0mm, although the ferrite powder sample (20F) can obtain about 11dB of radio wave absorption near 1.5GHz, the ratio to stainless steel is 20vol% (20FS 14), 60vol% ( 20FS32), 80vol% (20FS41) samples can respectively obtain about 18dB, 26dB, 25dB of radio wave absorption in the vicinity of 2...

Embodiment 2

[0061] A laminated magnetic wood sample was prepared under the same conditions as in Example 1 except that the thickness of the magnetic layer was 1.0 mm. Figure 4 (A) and (B) show the measurement results of the radio wave absorption in the range of measurement frequency 0.05-12 GHz. For samples with only ferrite powder (20F) and stainless steel powder with a ratio of 40vol% (20FS23), radio wave absorption of 30dB and 25dB can be obtained at around 7GHz and 6GHz, respectively. The lower the internal ratio of the stainless steel powder, the higher the radio wave absorption tends to be. Also, as the internal ratio increases, the radio wave absorption capacity tends to decrease, and at the same time, the center frequency tends to shift to a lower frequency.

Embodiment 3

[0063] Except that the internal ratio (S:F) of ferrite powder and stainless steel powder is 2:3, and the thickness of the magnetic layer is respectively set to 0.5mm, 1.0mm, 1.5mm, 2.0mm, 4.0mm, the rest is the same as in Example 1 conditions to make laminated magnetic wood samples. Fig. 5 shows the measurement results of the radio wave absorption in the measurement frequency range of 0.05 to 12 GHz. When the thickness of the magnetic layer is 1.5mm, the maximum radio wave absorption of about 30dB can be obtained around 4.5GHz. It can be seen that as the thickness of the magnetic layer increases, the center frequency will shift to the low frequency band. In addition, when the internal ratio of the stainless steel powder is low, the thinner the magnet layer, the higher the radio wave absorption tends to be.

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Abstract

Various electric wave absorbers for the GHz band have been developed. However, parameters for obtaining the optimal electric wave absorption characteristic are only the shape and the content of a dielectric material or a conductive material, and the degree of freedom of the parameters is small. Furthermore, in a recent wireless LAN, electric wave absorbers that can be used for absorbing potentially electric waves in a plurality of bands, for example, in two frequency bands of 2.45 GHz band and 5.2 GHz band, have also been desired. A woody electric wave absorber is also disclosed, characterized in that it is a laminate type magnetic wood prepared by pressure-pasting an opposed plate material pair comprising natural wood or a processed woody material via a magnetic layer containing a ferrite powder, it contains a non-magnetic stainless steel powder in an amount of 20 to 80 vol % relative to the ferrite powder, and the magnetic layer has a total volume content for the ferrite powder and the non-magnetic stainless steel powder of 10 to 40 % and has a thickness of 0.5 to 5.0 mm, it has a central frequency within 1 to 8 GHz, and has an electric wave absorption characteristic of 10 dB or more in a 2.45 GHz band or a 5.2 GHz band of frequency.

Description

technical field [0001] The present invention relates to a wood-based radio wave absorbing material that has excellent performance in absorbing radio waves in the several GHz band of mobile phones, etc., and can easily adjust the performance. Background technique [0002] As for the dielectric loss material or conductive loss material of the radio wave absorber, ferrite or carbon is mainly used in the frequency range of 10 MHz to 1 GHz. In addition, in the frequency band above 1 GHz, conductive metal plates, metal meshes, metal fibers, etc. are used. These materials are usually used as plate-shaped electromagnetic wave absorbers compounded with plastic or rubber. [0003] Recently, especially thin radio wave absorbers corresponding to the GHz frequency band have been demanded, and various new materials are being widely developed. The powder of magnetoplumbite (magnetoplumbite) type hexagonal crystal ferrite is mixed into the holding material made of inorganic materials such...

Claims

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Application Information

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IPC IPC(8): H05K9/00H01Q17/00H01F1/00H01F1/37
CPCH01F1/37H01Q17/00H01F1/0027H01Q17/008Y10T428/2852Y10T428/12958Y10T428/31989B32B23/04E04C2/284H01F1/00H05K9/00
Inventor 冈英夫
Owner JAPAN SCI & TECH CORP
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