JPS58108602A - Radio wave absorber and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radio wave absorber. More specifically, the present invention relates to a radio wave absorber made of concrete containing carbon fiber and at least one carbonaceous material selected from spherical carbon, powdered carbon, and lumped carbon, and a method for manufacturing the same.

In recent years, TV ghost problems caused by structures such as buildings have become a major social problem. In particular, concrete, which is an excellent building material, has extremely poor radio wave absorption properties, so buildings with concrete walls are often the cause of radio wave interference.

One of the countermeasures against this radio wave interference is to install a radio wave absorbing plate on the wall of a building that completely absorbs the incoming rainbow waves and produces fewer reflected radio waves. Conventionally, carbon styrene foam, carbon rubber, ferrite powder rubber, and ferrite tiles have been used as materials for radio wave absorbing plates. Although these conventional absorbing plates have excellent radio wave absorption properties, they are too weak to be used as structural materials for buildings.

Ministry of the Invention Carbon Fiber T'6 in Concrete
In addition to the knowledge that the radio wave absorption properties of concrete can be completely improved by adding a thin layer to the concrete, the thickness The present invention was developed as a result of in-depth research into concrete that has a custom-made structure that absorbs light waves even though it is thin.

An object of the present invention is to provide a structural material for a building that exhibits optical radio wave absorption properties even if it is thin.

The radio wave absorber of the present invention is characterized in that it is made of concrete comprising carbon fibers and at least 1 rM of carbonaceous material selected from granular carbon (carbon beads), powdered carbon and lump carbon. .

The characteristics of at least one carbonaceous material selected from granular carbon, powdered carbon, and lumpy carbon and carbon fiber are determined by the thickness of the product, the desired kick wave absorption +! Note: Although a wide range of choices can be made depending on the intended use of the product and the installation location, it is common to use 0.5 to 10% carbon fiber, granular carbon, powdered carbon, and lump carbon to the product concrete. At least 11 selected insect carbonaceous substances 5
Preferably, the content is between 50% and 50%.

The carbon fiber used in the present invention may be any ordinary carbon fiber, for example, a fiber diameter of 5 to 30 μm and a fiber length of 0.3 to 30 μm.
15m length can be used.

Granular carbon is usually referred to as carbon beads, and is carbon particles that are almost spherical in shape9, and their strength is also lower than that of lumpy carbon.
The particle size is 50-1500μ. Powdered carbon refers to a powder-like system with a particle size much smaller than that of carbon beads.

Lumped carbon refers to carbon granules obtained by adding a binder to powdered carbon to form agglomerates, and has a particle size of 50μ to 1500μ.

The concrete used for the radio wave absorber of the present invention may be one that is normally used, and is made by distributing cement, water, fine aggregate, and if necessary, coarse aggregate in appropriate proportions, mixing it well, and making it suitable for use in the past. It is obtained by curing.

The concrete referred to in the present invention includes not only ordinary concrete but also mortar, lightweight concrete, and the like.

The radio wave absorber of the present invention can be manufactured in the same manner as ordinary concrete manufacturing. At least l selected from carbon fibers and granular carbon systems, pulverulent carbon and bulk carbon.
At any stage before curing, the carbonaceous material of the rod is uniformly mixed so that the cured product contains 0.5 to 10% by volume of carbon fibers and 5 to 50% by volume of the carbonaceous material. to house the poultry house.

That is, carbon fiber and carbonaceous carbonaceous materials may be mixed with cement first, water and aggregate or cement, water, fine aggregate and coarse aggregate mixed simultaneously. You may. Additionally, the carbon fibers and the carbon fibers may be mixed at separate stages of kneading.

The mixing ratio of cement, water, fine aggregate, etc. can be changed in the same way as for put'H concrete. Further, steel fibers and the like, which are usually used as sleeve binding materials, can also be mixed.

The concrete radio wave absorber of the present invention exhibits maximum absorption at different wavelengths depending on the carbonaceous material selected from granular carbon, powdered carbon, and lumpy carbon, carbon fiber shoulder wheel, water content, etc. Further, the thickness of the absorber of the present invention depends on the wavelength (λ) of the radio wave to be absorbed.

Therefore, it is preferable to design the uninvented one-wave absorber by appropriately selecting the carbon fiber, grain strength, and thickness to match the wavelength of the active wave to be absorbed. In addition, as shown in the examples below, the absorber of the present invention exhibits sharp frequency temporal characteristics, so the absorber exhibiting different frequency ah properties is made into a multi-no structure with two or more nos, and the wide frequency range %a is It is also the same to manufacture an absorbent body having -oJ i.

The radio wave absorber of the present invention is effective against radio waves of a wide range of wavelengths, but is effective against radio waves of TV liquid, Vl-IP, and UH1i' as a side dish.

Since the radio wave absorber of the present invention is made of concrete, it has high strength (for example, the compressive strength is approximately 220 to 32 oKg・f/l).
J) Therefore, it can be advantageously used as a structural material for buildings. yl
For example, it can be used as a panel for the walls of buildings, and it can also be manufactured on-site and used for lifting elevated bridge girders, etc. Furthermore, as is clear from the examples described later, the radio wave absorber of the present invention has the ability to absorb radio waves as much as light even if it is thin, so it is suitable for use as a construction panel. It can be used for.

Hereinafter, the present invention will be described in detail with reference to Examples. In addition, to express the time characteristic of −′ paper material, the complex dielectric constant “tr(−εI
It is known that r jε″r) is suitable, and this was also used in the following examples. Shows hemodynamic loss. That is, a material with a relatively large εnr can be used as a radio wave absorber.

Example 1 Chichibu Cement Co., Ltd. iA Cement 60 (1, Kenbetsu Kagaku Kogyo Co., Ltd. carbon fiber (average line? & height 18μ, average fiber length 0.7+Il+1I) 81.52, carbon beads (average particle size 300μ) ) 465F, water 400cc, and sand 80.6? were kneaded to obtain the mortar raw material of the present invention.

The one-wave characteristics of this mortar were investigated using a brass coaxial waveguide shown in Figure 1. In the waveguide shown in Figure 1,
The test concrete IJ-1 and IJ-2 are brass plates. 1 is the length of the specimen, which corresponds to the Jv of the concrete panel (
,, e = 10 an ).

The waveguide was filled with mortar having the composition as described above. Radio wave characteristics were measured after thoroughly drying to eliminate the influence of moisture. The obtained results are tr'=56.5, tr
” = 20.6.

Example y1] 2 to 12 Mortar was produced in the same manner as in Example 1, except that the cement, carbon fiber, carbon beads, sand, and water ridges were changed as shown in Table 1.

- The measurement results of wave direction characteristics are shown in the first column.

As a comparative example in which carbon beads and/or carbon fibers were not mixed, mortar was produced in the same manner as in Example 1 with the composition shown in Table 1. The measurement results of radio wave characteristics are shown in Table 1.

Example 13 Carbon fiber 5%, carbon beads 10%
Concrete panel of the main brother Akira (thickness 1 octn)
, a reflection loss frequency ridge with a width of 50 (WI% - IZ length of 50 m) was studied. The ending is shown in Figure 2. As is clear from the figure, the paper containing 5% carbon fiber and 10% F of carbon beads showed a sharp radio wave customization at 150 MHz.

Example 14 The thickness of a young fruit, that is, a panel exhibiting a reflection loss of 30 dB or more, was investigated when ff1 (i==) of the carbon fiber was kept approximately constant and the length of the carbon beads was increased.

The results when the radio wave Jkλ=150 crn are shown in Table 2, and the results when λ-300 cm are shown in Table 3.

As shown in Table 2, Table 3, by increasing the weight of the carbon beads, the radio wave customization was the same and the thickness of the channel could be made thinner.

[Brief explanation of drawings]

FIG. 1 shows the construction of a coaxial waveguide for measuring the radio wave characteristics of Akira Honji's radio wave absorber, and FIG. 2 shows the reflection loss frequency characteristics of the radio wave absorber of the present invention. 1... Concrete specimen, 2... Metal plate. Figure 1 Figure 2

Claims (1)

[Scope of Claims] (υ Concrete wave absorber containing carbon fiber and at least 1aI carbonaceous material selected from spherical carbon, powdered carbon, and lumpy carbon. (2) Spherical carbon, powdered carbon, and lumpy carbon The scope of the patent described in item (1) is characterized in that it contains 5 to 50% by volume of at least 1 yen carbonaceous material selected from carbon and 0.5 to 10% by volume of carbon fibers. Radio wave absorber. (3) At least one carbon IJI material selected from spherical carbon, powdered carbon, and lump carbon and carbon fiber are mixed into a concrete raw material consisting of at least cement and fine aggregate. Method for manufacturing a radio wave absorber. (4) The above-mentioned carbonaceous substance and carbon fiber are mixed into cement,
A method for manufacturing a radio wave absorber listed in S1 in item (3) of the patent application, which is characterized in that it is mixed with a raw material for concrete consisting of fine aggregate and coarse aggregate.