JPH09162589A - Radio wave absorbent and radio wave absorbing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide lightweight radio wave absorbent of simple structure which can be so arranged that optical transparency of arrangement part position is ensured. SOLUTION: Radio wave absorbing glass 10 is constituted by arranging many elements 14 of radio wave absorbent on one surface of a glass plate 12. In each element 14, material wherein a plurality of raw materials different in conductivity are compounded is used and molded in a line type. The kinds and the compounding ratio of a plurality of the raw materials, manufacturing method, the sectional area, etc., are so determined that the electric resistance value per unit length of each element 14 coincides with a specified value maximizing the radio wave absorbing performance (a value in a specified range which is higher than conductor and lower than insulator). The elements 14 are arranged in an array type on the glass plate 12 and stuck, in such a manner that the longitudinal directions of the elements 14 are identical, and a plurality of the elements 14 are aligned at specified intervals along the direction rectangular to the longitudinal direction of the elements 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave absorber and an electromagnetic wave absorbing method, and more particularly to an electromagnetic wave absorber that absorbs an incoming electromagnetic wave and an electromagnetic wave absorbing method for absorbing an incoming electromagnetic wave.

[0002]

2. Description of the Related Art
Electromagnetic waves (radio waves) are used in various fields such as radio, TV, wireless communication, etc., but so-called radio wave interference has been a problem from the past when various inconveniences are caused by interference of these radio waves with other radio waves. Has become. Examples of radio waves that cause radio wave interference include radio waves reflected by buildings and buildings such as steel towers, unnecessary radio waves emitted from electric and electronic devices, and the like. Of these, especially VHF and U
Radio waves in the TV frequency band, such as HF, are reflected by the building, and are generated when the radio wave directly arriving from the station (direct wave) and the radio wave reflected by the outer wall of the building (reflected wave) are incident on the receiving antenna. Reception obstacles such as ghosts have become a social problem with the increase in high-rise buildings in recent years.

Therefore, for the purpose of reducing the radio waves reflected on the outer wall of the building, a panel made of a magnetic material such as ferrite is attached or embedded in the outer wall of the building, and the radio waves arriving at the building are transmitted to the panel. Has been proposed so far (for example, Japanese Utility Model Laid-Open No. 53-11501 and Japanese Patent Publication No. 55).
-49797, etc.). However, although the ferrite panel has desirable characteristics that show high absorption performance for radio waves in a wide frequency band, it has a problem that it is expensive and heavy. Further, since the light transmittance of ferrite is almost 0, it was impossible to apply it to the windows of buildings. In addition, instead of a panel made of ferrite or the like, an outer wall of a building is formed of concrete mixed with a carbon chip or the like, but this type of concrete has a problem that sufficient electromagnetic wave absorption performance cannot be obtained. is there.

The present invention has been made in consideration of the above facts, and provides an electromagnetic wave absorber which is light in weight and has a simple structure, and which can be arranged so as to ensure the light transmittance of the installation site. That is the purpose.

Another object of the present invention is to obtain an electromagnetic wave absorption method capable of absorbing an incoming electromagnetic wave by a simple method.

[0006]

[Means for Solving the Problems] As an example, a conductor reflects incoming electromagnetic waves such that incoming electromagnetic waves are reflected by reinforcing bars embedded in concrete in a building wall formed of reinforced concrete. It is empirically known. On the other hand, the inventors of the present invention reflect / reduce the electromagnetic wave when the electric resistance value per unit length of a long object placed under the environment where the electromagnetic wave is irradiated is changed.
An experiment (simulation) was conducted to confirm how the ratio of absorption / transmission changes. Then, according to this experiment, the electric resistance per unit length of the long object is within a predetermined range (specifically higher than general conductors such as gold, copper, iron, etc., insulation of rubber etc.). It has been found that when the value is in a range lower than that of the body), the electromagnetic waves applied to the object are more likely to be absorbed by the object.

Based on the above, in the electromagnetic wave absorber according to the present invention, the electric resistance per unit length or the electric resistance per unit area along the predetermined direction is higher than that of the conductor and lower than that of the insulator. The element is adjusted to have a value within the range.

The element may have a long shape as described in claim 3 or a layered shape that covers a predetermined surface as described in claim 4, and may have any other shape than the above. It is also possible to apply shapes. However, since the direction of the alternating current induced by the incoming electromagnetic wave is parallel to the plane of polarization of the incoming electromagnetic wave, at least along the direction parallel to the plane of polarization of the incoming electromagnetic wave in the installed state. Therefore, it is desirable that the element has a shape that is continuous for a predetermined length or more. For example, when the element is elongated, it may be arranged so that the longitudinal direction of the element is substantially parallel to the plane of polarization of the incoming electromagnetic wave.

When the element has a long shape, the electric resistance value of the element is within a predetermined range, as described in claim 3, as the electric resistance per unit length along the longitudinal direction of the element. It may be adjusted so as to have a value (specifically, a value in a range higher than that of a general conductor and lower than that of an insulator). When the element is layered, as described in claim 4. The electric resistance per unit area may be adjusted to a value within a predetermined range.

The electrical resistance of the element does not depend only on the electrical conductivity of the material forming the element, but in the case of a long element, the electrical resistance per unit length also depends on the cross-sectional area of the element. In the case of a layered element, the electric resistance per unit area also changes depending on the thickness of the layer of the element, but the above specified range is the unit length or unit area of a general electric path formed by a conductor. The electric resistance value is higher than the electric resistance value per unit area, and is lower than the electric resistance value per unit length or unit area of the insulating portion made of an insulator.

When an electromagnetic wave arrives at the electromagnetic wave absorber according to the present invention, an alternating current flowing along the direction parallel to the plane of polarization of the incoming electromagnetic wave is induced in the element as described above. Since the electric resistance per unit length of the element or the electric resistance per unit area is adjusted to a value within a predetermined range, the alternating current induced in the element must be converted into thermal energy inside the element. As a result, re-radiation of electromagnetic waves from the element is suppressed, and good electromagnetic wave absorption performance is obtained. Further, in the above, since a good electromagnetic wave absorption performance can be obtained simply by providing the element, it is not necessary to use an expensive and heavy member such as a ferrite panel, and the structure can be light and simple.

Further, as described in claim 2, when a plurality of the elements are arranged in an array in a predetermined plane, the electromagnetic waves reflected at respective points in the predetermined plane where the electromagnetic waves arrive can be reduced. However, as described above, since the electromagnetic wave absorber according to the present invention has a good electromagnetic wave absorbing performance as described above, for example, an element formed of a material having no light transmittance is used, and the element is described above. Even when a plurality of such elements are arranged in an array on a predetermined surface, it is not necessary to cover the entire predetermined surface with elements, and the elements are arranged so that a gap is formed between adjacent elements. It is also possible to arrange so that the light transmittance of the provided portion is secured.

[0013] The invention of claim 5 is the invention of claims 1 to 4.
In any one of the above aspects, the element is provided with a load resistance.

In the present invention, since the alternating current induced in the element by the arrival of the electromagnetic wave is converted into heat energy inside the element, a good electromagnetic wave absorbing performance can be obtained by the element alone. If a load resistance is provided in the, the induced alternating current is converted into heat energy even in the load resistance, so that the electromagnetic wave absorption performance is further improved. The load resistance may be provided in the middle of the element (intermediate portion along the longitudinal direction of the elongated element, inside the layered element, or the like) or at the end of the element.

When an electromagnetic wave arrives at the element, an alternating current is induced in the element. The range of movement of charges in the element due to this alternating current depends on the wavelength of the incoming electromagnetic wave, and the wavelength of the electromagnetic wave is short (frequency is low). The higher the value), the smaller the charge transfer range. When the electromagnetic wave is absorbed only by the element without providing the above-mentioned load resistance, the length of the element along the direction parallel to the polarization plane of the incoming electromagnetic wave is sufficiently long compared with the moving range of the electric charge. However, if a load resistor is provided,
If the frequency of the electromagnetic wave to be absorbed is high and the length of the element along the direction parallel to the plane of polarization of the incoming electromagnetic wave is longer than the moving range of the electric charge, the electric charge does not reach the load resistance, and the load resistance is provided. In some cases, the electromagnetic wave absorption performance cannot be improved.

Therefore, the invention of claim 6 is the same as claim 5 of the invention.
In the invention, the element is characterized in that the length along the direction parallel to the polarization plane of the incoming electromagnetic wave corresponds to the frequency of the electromagnetic wave to be absorbed.

In the above description, the length of the element along the direction parallel to the plane of polarization of the incoming electromagnetic wave corresponds to the frequency of the electromagnetic wave to be absorbed, so that when the frequency of the electromagnetic wave to be absorbed is high. Also, the electromagnetic wave absorption performance can be improved by the charge moving by the induced alternating current reaching the load resistance, and the alternating current being also converted into thermal energy by the load resistance.

If the length of the element is set to a length corresponding to the frequency of the electromagnetic wave to be absorbed, a standing wave is generated on the element by the electromagnetic wave of the frequency to be absorbed. Therefore, the point where the current on the element becomes maximum and the point where the received power becomes maximum are determined.If a load resistance is provided at the point where this current becomes maximum or the received power becomes maximum, it is absorbed. It is possible to more efficiently absorb an electromagnetic wave having a desired frequency. The length of the element described above can be set to a length that is a little shorter than the length of 1/2 of the wavelength of the electromagnetic wave to be absorbed, further considering the wavelength shortening rate.

According to the invention of claim 5, when it is desired to absorb electromagnetic waves of a plurality of kinds of frequencies, respectively,
As described above, if a plurality of different types of elements having different lengths along the direction parallel to the plane of polarization of the incoming electromagnetic wave are provided in correspondence with the frequencies of the different types of electromagnetic waves to be absorbed. A high electromagnetic wave absorption performance is obtained for each electromagnetic wave of each frequency to be absorbed.

When an AC current is induced in the element by the incoming electromagnetic wave, a magnetic field is induced by this AC current according to the right-handed screw law, and an electric field is induced by this magnetic field according to the electromagnetic induction law. Since the magnetic field and the electric field are alternating currents, they cause re-radiation of electromagnetic waves from the electromagnetic wave absorber according to the present invention.

Therefore, the invention of claim 8 is the same as claim 1
The invention according to any one of claims 7 to 7 is characterized in that at least one of a magnetic material and a ferroelectric material is arranged around or in the vicinity of the element.

As the magnetic material, for example, a magnetic material such as a magnetic ring can be applied. When the magnetic body ring is arranged, the induced magnetic field is taken into the magnetic body ring, and the magnetic field energy is absorbed by the energy of the magnetic field being converted into thermal energy by the imaginary component of the magnetic permeability of the magnetic body ring.

Further, as the magnetic material, a magnetic fluid or magnetic powder or a mixture containing at least one of magnetic fluid and magnetic powder may be applied. When the magnetic fluid or magnetic powder or the mixture is arranged, the magnetic substance, the magnetic fluid, the magnetic powder or the mixture is magnetized by the induced magnetic field, and the state of the magnetization is cyclic according to the periodic change of the magnetic field. Change. As a result, the magnetic field is converted into heat energy by the imaginary number component of the magnetic permeability of the magnetic fluid or magnetic powder or mixture and absorbed, or the primary magnetic field physically vibrates the magnetic substance or magnetic fluid or magnetic powder or mixture. By doing so, it is converted into heat energy and absorbed.

Further, when the ferroelectric material is arranged, the direction of polarization of the ferroelectric material periodically changes in accordance with the periodic change of the induced electric field, so that (the electric flux due to) the electric field. Is converted into heat energy and absorbed.

As described above, in the invention of claim 8, by disposing at least one of the magnetic material and the ferroelectric material, the magnetic field or electric field induced by the alternating current induced in the element is converted into thermal energy. As a result, the electromagnetic wave re-radiated from the electromagnetic wave absorber is reduced, and the electromagnetic wave absorbing performance of the electromagnetic wave absorber can be further improved.

According to a ninth aspect of the present invention, there is provided an electromagnetic wave absorbing method, wherein the electromagnetic wave absorber according to any one of the first to eighth aspects is arranged at a location where an electromagnetic wave arrives.

According to the ninth aspect of the invention, the electromagnetic wave absorber described above can be absorbed only by providing the electromagnetic wave absorber described above at a position where the electromagnetic wave arrives, and any of the electromagnetic wave absorbers described above is extremely excellent. Since it has a simple structure, it is easy to dispose, and the incoming electromagnetic waves can be absorbed by a simple method. The position where the electromagnetic wave absorber is provided is not limited to the outside or the inside of the building, and the electromagnetic wave absorber may be provided in, for example, an electric / electronic device or vehicle equipped with an electromagnetic wave radiation source. As a result, the electromagnetic wave emitted from the electromagnetic wave radiation source is absorbed by the electromagnetic wave absorber,
Radiation of electromagnetic waves from electric / electronic devices, vehicles, etc. to the outside can be reduced.

According to a tenth aspect of the present invention, there is provided an electromagnetic wave absorbing method, wherein the electromagnetic wave absorber according to any one of the first to eighth aspects is arranged at a location where an electromagnetic wave arrives, and the electromagnetic radiation is transmitted through the location. In order to absorb the electromagnetic wave or reduce the electromagnetic wave that arrives at the place, the method according to claim 1 to claim 8.
The electromagnetic wave absorber according to any one of items 1 to 5 is further provided.

Since the electromagnetic wave absorber according to any one of claims 1 to 8 cannot absorb all the incoming electromagnetic waves, it may be required to have a higher electromagnetic wave absorbing performance depending on the application. On the other hand, claim 10
In the invention, the electromagnetic wave absorber is provided at a place where the electromagnetic wave arrives, and the electromagnetic wave absorber is further provided to absorb the electromagnetic wave transmitted through the place or reduce the electromagnetic wave coming to the place.

For example, when the electromagnetic wave absorber according to the present invention is arranged in a window of a building where electromagnetic waves arrive,
If the electromagnetic wave absorber according to the present invention is further arranged on the lattice or screen door located outside the window, a part of the electromagnetic wave coming from the outside of the building is absorbed by the lattice or screen door. Therefore, the electromagnetic waves that reach the window can be reduced. Further, when the electromagnetic wave absorber according to the present invention is arranged in a curtain arranged inside the window, a blind, a partition installed in a room, furniture, etc., the electromagnetic wave transmitted through the window becomes the curtain. Absorbed by blinds, partitions, furniture, etc.

Therefore, even when the required electromagnetic wave absorption performance cannot be satisfied by a single electromagnetic wave absorber, the electromagnetic wave absorbers according to the present invention are arranged in multiple layers as described above, so that multiple electromagnetic wave absorbers can be used. The electromagnetic wave absorbing performance of the electromagnetic wave absorber disposed in the above is integrated, and high electromagnetic wave absorbing performance satisfying the requirements can be obtained.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In the following, a glass plate, which is a type of construction member, will be described as an example in which the electromagnetic wave absorber according to the present invention is included.

[First Embodiment] FIG. 1 shows an electromagnetic wave absorbing glass 10 according to the first embodiment. The electromagnetic wave absorbing glass 10 is configured by providing a large number of elements 14 of the electromagnetic wave absorber according to the present invention on one surface of the glass plate 12. Each element 14 is formed by using a material formed by mixing a plurality of raw materials having different electric conductivity, and molding the material into a linear shape (long shape). In addition, as the plurality of raw materials, for example, metals, alloys, carbon, various organic substances, and the like can be used.

The electric resistance value per unit length of each element 14 is a predetermined value (higher than the conductor and lower than the insulator) experimentally determined so as to maximize the electromagnetic wave absorption performance. Values, the types and blending ratios of multiple raw materials, the manufacturing method of the material, the cross-sectional area, etc. are determined (the conductivity of the material varies depending on the type and mixing ratio of raw materials, manufacturing method, etc.). , The electric resistance value per unit length varies depending on the conductivity and cross-sectional area of the material). In addition, each element 14 has its longitudinal direction oriented in the same direction (the left-right direction in FIG. 1), and a plurality of elements 14 are arranged at predetermined intervals along a direction orthogonal to the longitudinal direction of the element 14. , Are arranged and attached in an array on one surface of the glass plate 12.

Next, the operation of the first embodiment will be described. The electromagnetic wave absorbing glass 10 is disposed as a window glass in a building, and at this time, the longitudinal direction of the element 14 is substantially parallel to the direction of the plane of polarization of the electromagnetic wave reaching the building (for example, horizontal polarization). When the electromagnetic wave arrives, the vertical direction of FIG. 1 is arranged in the same direction as the vertical direction of the building).

When an electromagnetic wave arrives at the building in the state where it is arranged in the building as described above, each element 14 is provided with a direction parallel to the plane of polarization of the incoming electromagnetic wave, that is, along the longitudinal direction of each element 14. Although an alternating current flowing through the element 14 is induced, as described above, the electric resistance per unit length of the element 14 is set to a predetermined value (a value within a predetermined range higher than the conductor and lower than the insulator). , Each element 14
The alternating current induced in the element 14 is converted into heat energy inside the element 14. Since the converted thermal energy does not contribute to the re-radiation of the electromagnetic wave from the element 14, the re-radiation of the electromagnetic wave from each element 14 is suppressed, and a good electromagnetic wave absorbing performance can be obtained over the entire surface of the electromagnetic wave absorbing glass 10.

Further, since the respective elements 14 are lined up with a predetermined gap along the direction orthogonal to the longitudinal direction,
Light is transmitted through the gaps between the elements 14, and the light transparency required for the window glass of the building is secured.

It should be noted that the movement range of charges in the element 14 due to the alternating current induced in the element 14 is
Element 1 if larger than element 14 length
At the end of 4, the current is reflected, and the reflected current causes re-radiation of electromagnetic waves. The moving range of the electric charge inside the element 14 due to the arrival of the electromagnetic wave is ½ of the wavelength of the incoming electromagnetic wave, so the length of the element 14 is ½ of the maximum value of the wavelength of the electromagnetic wave to be absorbed. The above is preferable.

[Second Embodiment] Next, a second embodiment of the present invention will be described. The same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 2, the electromagnetic wave absorbing glass 16 according to the second embodiment is different from the electromagnetic wave absorbing glass 10 described in the first embodiment in that one end of each element 14 has a glass plate 12. A pair of electromagnetic wave absorbing glasses 18 extending to the ends are provided, and the pair of electromagnetic wave absorbing glasses 18 is provided.
Both of the extended elements 14 are connected to each other via a load resistor 20. Further, the pair of electromagnetic wave absorbing glasses 18 are joined by a glass joining material.

Next, the operation of the second embodiment will be described. The electromagnetic wave absorbing glass 16 according to the second embodiment is also arranged such that the longitudinal direction of the element 14 is substantially parallel to the direction of the plane of polarization of the electromagnetic waves reaching the building. The portion joined by the glass joining material may be exposed, but it is preferably aesthetically covered with a window frame or the like.

When an electromagnetic wave arrives at a building in which the electromagnetic wave absorbing glass 16 is arranged, an alternating current is induced in each element 14, and this alternating current flows through a pair of electromagnetic resistance absorbing glass 18 through a load resistance. It flows over both elements 14. As a result, the induced alternating current is converted into thermal energy inside the element 14 and also converted into thermal energy by the load resistor 20,
Electromagnetic wave absorption performance is improved as compared with the electromagnetic wave absorption glass 10 of the first embodiment.

Since both elements 14 of the pair of electromagnetic wave absorbing glasses 18 are connected via the load resistance, the physical length of the element 14 is long. Therefore, for the reason that the size of the window is small, or the maximum value of the wavelength of the electromagnetic wave to be absorbed is large (the frequency is low), the element for the wavelength of the electromagnetic wave to be absorbed in the electromagnetic wave absorbing glass 10 according to the first embodiment is Even when the length of 14 cannot be made sufficiently long, by using the electromagnetic wave absorbing glass 16 according to the second embodiment, re-radiation of electromagnetic waves due to reflection of current at the end of the element 14 is prevented. be able to.

In the above, a pair of electromagnetic wave absorbing glasses 1 is used.
Although both elements 14 of No. 8 are connected via the load resistance, both elements 14 may be simply electrically connected. In this case, although the electromagnetic wave absorption performance is lower than when the load resistor 20 is provided, compared with the electromagnetic wave absorption glass 10 described in the first embodiment, the electromagnetic wave absorption performance for electromagnetic waves having a relatively low frequency is improved. To do.

In the above, a pair of electromagnetic wave absorbing glasses 1 is used.
Although the eight elements 14 are connected, three or more electromagnetic wave absorbing glass elements may be connected.

[Third Embodiment] Next, a third embodiment of the present invention will be described. The same parts as those in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 3, the electromagnetic wave absorbing glass 22 according to the third embodiment has a load resistor 24 at the center in the longitudinal direction.
The element 26 having a certain length and provided with the glass plate 1
A large number of them are arranged in an array on one surface of No. 2. The length of the element 26 is set to be a half of the wavelength of the electromagnetic wave having a specific frequency to be absorbed, and slightly shorter in consideration of the wavelength shortening rate.

The electromagnetic wave absorbing glass 22 is similar to the electromagnetic wave absorbing glass 16 described above in that the alternating current induced by the incoming electromagnetic wave is applied to the element 26 and the load resistor 2.
The incoming electromagnetic wave is absorbed by being converted into heat energy by 4, but a standing wave (current) is generated in the element 26 when the electromagnetic wave of the specific frequency arrives. Since the load resistance 24 is arranged at the point where the electric current is maximum in this standing wave, that is, at the center of the element 26 in the longitudinal direction, the standing wave current is efficiently converted into heat energy, and the load frequency of the incoming specific frequency is increased. It can absorb electromagnetic waves with a high absorption rate.

Although the length of the element 26 is constant in the above description, when it is desired to absorb electromagnetic waves having a plurality of different frequencies, as shown in FIG. 4, for example, the length corresponding to each frequency is increased. A plurality of sets of different types of elements 26 and load resistors 24 having different heights may be provided in an array. Note that FIG. 4 shows an example in which a plurality of sets of three types of elements 26A or elements 26B or 26C and load resistors 24 having different lengths corresponding to three types of frequencies are provided in an array. .

Although the element 14 is provided on only one side of the glass plate 12 in the above description, it may be provided on both sides or may be embedded inside. Further, the glass plates 12 provided with the elements 14 may be laminated and the electromagnetic wave absorber according to the present invention may be multiply provided to form the electromagnetic wave absorption glass. in this case,
The electromagnetic wave absorption ratio of each element does not change, but the electromagnetic wave absorbing performance of the electromagnetic wave absorbing glass is improved.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. FIG. 6 shows an electromagnetic wave absorption panel 42 according to the fourth embodiment. Although the elements are linear (long) in the first to third embodiments described above, the patch antenna type electromagnetic wave absorption panel 42 is used.
Has a flat plate-shaped (layered) element 44 adjusted so that the electric resistance per unit area is higher than that of the conductor and lower than that of the insulator. A plurality of substrates are arranged in an array on the substrate 46.

The element 44 and the substrate 46 may be made of a material having no light transmissive property. However, in addition to the electric conductivity, the light transmissivity is also taken into consideration to determine the kind and mixing ratio of the raw materials. If the element 44 is formed and the substrate 46 is formed of a light transmissive material, the electromagnetic wave absorption panel 42 can be disposed at a place where light transmissivity is required. The element 44 may be formed on the substrate 46 by vapor deposition, or may be manufactured separately from the substrate 46.
It may be attached on the substrate 46.

When an electromagnetic wave arrives at the electromagnetic wave absorption panel 42, an AC current flowing in a direction parallel to the plane of polarization is induced in each element 44 regardless of the direction of the plane of polarization of the incoming electromagnetic wave. Since the electric resistance per unit area of 44 is higher than that of the conductor and lower than that of the insulator within a predetermined range, the alternating current induced in each element 44 is converted into heat energy inside the element 14. It Therefore, regardless of the direction of the plane of polarization of the incoming electromagnetic wave, good electromagnetic wave absorbing performance can be obtained over the entire surface of the electromagnetic wave absorbing panel 42.

By the way, in the flat plate-shaped element 44 shown in FIG. 6, the resonance frequency for an electromagnetic wave whose plane of polarization is parallel to the X direction of FIG. 6 is determined by the length of the element 44 along the X direction, and the plane of polarization is shown. The resonant frequency of the electromagnetic wave 6 parallel to the Y direction is determined by the length of the element 44 along the Y direction. For this reason, when it is desired to absorb electromagnetic waves of specific frequencies different depending on the polarization directions, if the lengths of the element 44 along the X direction and the Y direction are set to correspond to the specific frequencies to be absorbed, It is possible to efficiently absorb two types of electromagnetic waves having different polarization directions and frequencies.

Incidentally, as shown in FIG.
Instead of the above, the disk-shaped element 48 may be used to configure the radio wave absorption panel 42. With respect to the disk-shaped (layered) element 48, the resonance frequency for the electromagnetic wave in the predetermined polarization direction is determined by the diameter of the element 48 along the direction parallel to the polarization direction, and thus the identification is different depending on the polarization direction. When it is desired to absorb the electromagnetic wave of the frequency, the shape may be elliptical. Further, when it is desired to absorb a plurality of types of electromagnetic waves having the same polarization direction but different frequencies, FIG.
As shown in (A) and (B), the elements 44A, 44B, and 44C having different sizes are provided with insulating layers 50A and 5A.
You may laminate | stack via 0B.

The element of the electromagnetic wave absorber according to the present invention may be formed into a layered shape, a long shape, or an arbitrary shape by injecting conductive ions into an insulating material. It is possible.

In the above, an example in which the electromagnetic wave absorber according to the present invention is arranged on a glass plate used as a window glass of a building has been described, but the invention is not limited to the above.
For example, it may be woven into a fabric such as a curtain, embedded in concrete or the like, or attached to a sheet material such as a curing sheet used in construction work. If the material around the electromagnetic wave absorber may corrode the electromagnetic wave absorber over time when it is buried in concrete, take measures to prevent corrosion by coating the surface. It may be buried after the application.

In the above embodiment, the glass plate, which is a kind of construction member, is described as an example including the electromagnetic wave absorber according to the present invention. However, the outer wall panel, the inner wall panel, the handrail, It is possible to dispose the electromagnetic wave absorber described above on a blind or various construction materials described later. For example, if an outer wall of a building is constructed by using an outer wall panel in which an electromagnetic wave absorber is arranged in advance, or if the electromagnetic wave absorber is embedded in the outer wall at the time of construction of the building, the electromagnetic wave arrives from the outside The electromagnetic waves re-radiated from the outer wall of the building can be reduced, and the occurrence of radio interference such as reception failure around the building can be prevented.

If the inner wall of a building is constructed using an interior panel in which an electromagnetic wave absorber is arranged in advance, or if the electromagnetic wave absorber is embedded in the inner wall during construction of the building, the electromagnetic wave is radiated inside the building. Even if the source is provided, leakage to the outside of the building can be reduced. Further, if electromagnetic wave absorbers are provided on the wall surface, floor surface and ceiling surface of a specific room in a building, the electromagnetic wave leaks from the specific room and the electromagnetic waves enter the specific room from the outside. Can be reduced, and the specific room can be used as a so-called anechoic chamber.

Further, the electromagnetic wave absorber described above may be multiply arranged at at least a plurality of places, for example, in a lattice, a screen door, a window glass, a sash, a curtain, a blind, a partition or furniture installed in the room. For example, the electromagnetic wave absorption performance of multiple electromagnetic wave absorbers is integrated,
High electromagnetic wave absorption performance can be obtained.

As an example, FIG. 5 shows a linear shape in which the electric resistance value per unit length as the electromagnetic wave absorber of the present invention is adjusted in order to absorb the horizontally polarized electromagnetic wave coming from the outside of the building. A grid 30 and a screen door 3 in which an element (not shown) is incorporated so that the longitudinal direction of the element is along the horizontal direction.
2, window glass 34, blinds 36 and curtains 38 are shown. In addition, since the surroundings of the element must be insulated (not in contact with other conductors), the grid 3
0, the screen door 32, and the blind 36 are made of an insulating material (the glass of the window glass 34 and the fibers of the curtain 38 are also an insulating material), and the element is embedded or woven (curtain or the like) inside them, It is incorporated by pasting. If a plurality of arbitrary members among these members are multiply arranged (FIG. 5 shows an example in which the window glass 34, the blind 36 and the curtain 38 are multiply provided),
A high electromagnetic wave absorption performance is obtained as a whole, and the electromagnetic waves reflected and transmitted through the places where the members incorporating the elements are multiply provided are greatly reduced.

When the incoming electromagnetic waves are vertically polarized waves, if the gratings and blinds are such that the components extend along the vertical direction (direction that is substantially vertical when arranged), , Because the elements can be incorporated along this component.

A magnetic material such as a magnetic material such as a magnetic ring, a magnetic fluid, a magnetic powder, a mixture containing at least one of a magnetic fluid and a magnetic powder, or the like around or near the element,
A ferroelectric material such as liquid crystal may be provided. For example, in the embodiment shown in FIGS. 1 to 4, it is formed so as to cause a magnetic loss or a dielectric loss by applying a magnetic material or a ferroelectric material to the surface of the element or adding a magnetic material or a ferroelectric material. This can be realized by forming the glass plate 12 from the glass. Further, in the embodiment shown in FIGS. 6 to 8, the substrate 46 is made of the insulating material formed so as to cause the magnetic loss or the dielectric loss by adding the magnetic material or the ferroelectric material, and the insulating layer 50 is formed. It can be realized by doing. As a result, the magnetic field or electric field induced by the alternating current induced in the element is converted into thermal energy by the magnetic material or ferroelectric material described above and absorbed, thereby further improving the electromagnetic wave absorption performance of the electromagnetic wave absorber. be able to.

Also, the electromagnetic wave absorber described above is attached to a sheet material, such as a curing sheet or a fall prevention net, which is arranged between an incoming electromagnetic wave and a worker in a construction work or the like. May be. As a result, it is possible to protect the worker who works in a region where the electric field strength of the incoming electromagnetic wave is high, from the incoming electromagnetic wave.

Furthermore, the electromagnetic wave absorber according to the present invention is not limited to being applied to a construction member. For example, when the electromagnetic wave absorber according to the present invention is attached to an object such as the tip of a wing of an aircraft such as a military aircraft where it is not desirable to re-radiate an incoming electromagnetic wave, the electromagnetic wave is re-radiated from the object. Electromagnetic waves can be reduced.

In general, electromagnetic waves are emitted from electric / electronic devices that handle high-frequency currents, or from electric / electronic devices equipped with electromagnetic wave radiation sources (devices equipped with cathode ray tubes, microwave ovens, etc.), although they are weak. . When the electromagnetic wave absorber described above is provided in such an electric / electronic device, the electromagnetic wave emitted from the electric / electronic device can be reduced, and the influence of the emitted electromagnetic wave on the human body can be reduced. Also, it is possible to reduce radio wave interference due to radiated electromagnetic waves.

[0067]

EXAMPLES Next, experiments (simulations) conducted by the inventors of the present application will be described. This simulation uses an analytical model of 30 cm for a 0.4 mm diameter element.
A flat plate placed infinitely at intervals is used.
Irradiation of an electromagnetic wave of H _z plane wave was performed, and changes in the absorption, transmission, and reflection ratios of the electromagnetic wave were confirmed while changing the conductivity of the element. The experimental results are shown in FIG.

As is apparent from FIG. 9, when the conductivity of the element is 5000 S / m or more, the irradiated electromagnetic wave is 40
% Has also been absorbed. In FIG. 9, the maximum absorption of electromagnetic waves is 10000 S / m, but the electric resistance per unit length at this time is 796 Ω / m, which is the same as that of a general conductor (conductivity is 1000000 S / m or more). It is obviously higher than the electrical resistance per unit length. It is known that most of the electromagnetic waves emitted from a general conductor are reflected, so
It can be understood that high electromagnetic wave absorption performance can be obtained by adjusting the electric resistance per unit length of the element to a proper value within a range lower than that of a general conductor and higher than that of an insulator.

[0069]

As described above, the invention according to claim 1 is excellent in that it can be arranged with a light weight and a simple structure so as to ensure the light transmittance of the installation site. Have an effect.

According to the invention of claim 2, in addition to the above effects,
It is possible to reduce the electromagnetic waves reflected at each position on the predetermined plane where the electromagnetic waves arrive.

The invention described in claim 5 has an effect that the electromagnetic wave absorption performance can be further improved.

The invention according to claim 6 has an effect that the electromagnetic wave absorbing performance can be improved even when the frequency of the electromagnetic wave to be absorbed is high.

The invention according to claim 7 has an excellent effect that a high electromagnetic wave absorbing performance can be obtained for each electromagnetic wave of each frequency to be absorbed.

The invention described in claim 8 has an effect that the electromagnetic wave re-radiated from the electromagnetic wave absorber is reduced and the electromagnetic wave absorbing performance of the electromagnetic wave absorber can be further improved.

The invention according to claim 9 has an excellent effect that an incoming electromagnetic wave can be absorbed by a simple method.

According to the tenth aspect of the invention, even when the electromagnetic wave absorbing performance required by a single electromagnetic wave absorbing body cannot be satisfied, the electromagnetic wave absorbing performances of the multiple electromagnetic wave absorbing bodies are integrated. This has an excellent effect that a high electromagnetic wave absorption performance satisfying the requirements can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an electromagnetic wave absorbing glass according to a first embodiment.

FIG. 2 is a perspective view showing an electromagnetic wave absorbing glass according to a second embodiment.

FIG. 3 is a perspective view showing an electromagnetic wave absorbing glass according to a third embodiment.

FIG. 4 is a perspective view showing another example of the electromagnetic wave absorbing glass according to the present invention.

FIG. 5 is a schematic view showing an example in which a grid, a screen, a glass, a blind, and a glass among blinds, a blind, and a curtain in which the elements of the electromagnetic wave absorber according to the present invention are incorporated are multiply provided.

FIG. 6 is a perspective view showing an example of an electromagnetic wave absorption panel according to a fourth embodiment.

FIG. 7 is a perspective view showing another example of the electromagnetic wave absorption panel.

FIG. 8A is a perspective view of another example of the electromagnetic wave absorption panel,
(B) is a side view of (A).

FIG. 9 is a diagram showing a result of an experiment (simulation) performed by the inventors of the present application.

[Explanation of symbols]

 10 Electromagnetic Wave Absorption Glass 14 Element 16 Electromagnetic Wave Absorption Glass 20 Load Resistance 22 Electromagnetic Wave Absorption Glass 24 Load Resistance 26 Element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Murai 1-5 Otsuka, Inzai-cho, Inba-gun, Chiba Takenaka Corporation Technical Research Institute

Claims (10)

[Claims] 1. An element adjusted so that the electric resistance per unit length or the electric resistance per unit area along a predetermined direction is higher than that of a conductor and lower than that of an insulator within a predetermined range. Electromagnetic wave absorber. 2. The electromagnetic wave absorber according to claim 1, wherein a plurality of the elements are arranged in an array in a predetermined plane. 3. The element has a long shape and is adjusted so that the electric resistance per unit length along the longitudinal direction is a value within the predetermined range, and the deviation of electromagnetic waves coming in the longitudinal direction is obtained. The electromagnetic wave absorber according to claim 1 or 2, wherein the electromagnetic wave absorber is arranged substantially parallel to the wavefront. 4. The electromagnetic wave according to claim 1, wherein the element is layered so as to cover a predetermined surface, and the electric resistance per unit area is adjusted to be a value within the predetermined range. Absorber. 5. The element according to claim 1, wherein a load resistance is provided on the element.
The electromagnetic wave absorber according to the item. 6. The element according to claim 5, wherein the length of the element along the direction parallel to the polarization plane of the incoming electromagnetic wave corresponds to the frequency of the electromagnetic wave to be absorbed. Electromagnetic wave absorber. 7. A plurality of types of elements having different lengths along the direction parallel to the plane of polarization of the incoming electromagnetic waves are provided corresponding to the frequencies of a plurality of different types of electromagnetic waves to be absorbed. The electromagnetic wave absorber according to claim 5, characterized in that: 8. The electromagnetic wave absorber according to any one of claims 1 to 7, wherein at least one of a magnetic material and a ferroelectric material is arranged around or near the element. . 9. An electromagnetic wave absorption method in which the electromagnetic wave absorber according to any one of claims 1 to 8 is disposed at a location where an electromagnetic wave arrives. 10. The electromagnetic wave absorber according to any one of claims 1 to 8 is arranged at a location where an electromagnetic wave arrives, and the electromagnetic wave transmitted through the location is absorbed or arrives at the location. An electromagnetic wave absorption method further comprising the electromagnetic wave absorber according to any one of claims 1 to 8 in order to reduce the electromagnetic waves generated.