JP2002076672A - Electromagnetic wave absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen the electromagnetic wave absorbing band of an electromagnetic wave absorber and, at the same time, to reduce the thickness of the absorber. SOLUTION: A reflecting film 18 is formed on an insulating substrate 14 of insulating substrates 12A, 12B, and 14 which are arranged in parallel with each other at fixed intervals and, at the same time, resistance films 16 and split conductive films 66 are respectively provided on the substrates 12A and 12B. Then the distance between the first resistance film 16 on the substrate 12A and the second resistance film 16 on the substrate 12B is made different from the distance between the second resistance film 16 and reflecting film 18. Consequently, the electromagnetic wave absorbing band of the electromagnetic wave absorber can be widened, because, when electromagnetic waves arrive from the substrate 12A side, the frequency f1 at which the electromagnetic wave reflected by the first reflecting film 16 and the electromagnetic wave reflected by the second resistance film 16 become opposite in phase, the frequency f2 at which the electromagnetic wave reflected by the first resistance film 16 and the electromagnetic wave reflected by the reflecting film 18 become opposite in phase, and the frequency f3 at which the electromagnetic wave reflected by the first resistance film 16 and the electromagnetic wave reflected by the reflecting film 18 become opposite in phase are different from each other. In addition, the thickness of the absorber can be reduced by the split conductive films 66.

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 more particularly, to an electromagnetic wave absorber that absorbs an electromagnetic wave by superimposing an electromagnetic wave having an opposite phase on the electromagnetic wave to be absorbed.

[0002]

2. Description of the Related Art At present, electromagnetic waves (radio waves) are radio, TV,
It is used in various fields such as mobile phones, wireless communications, and the like. However, so-called radio interference, which causes various inconveniences due to interference of these electromagnetic waves with other electromagnetic waves, has conventionally been a problem. Examples of the electromagnetic wave that causes the radio wave interference include an electromagnetic wave reflected by a building such as a building and a steel tower, and an unnecessary electromagnetic wave radiated from electric / electronic devices. Among them, especially T of VHF and UHF
The electromagnetic wave in the V frequency band is reflected by the building, and the ghost and the like caused by the electromagnetic wave (direct wave) directly arriving from the station and the electromagnetic wave (reflected wave) reflected by the outer wall of the building being incident on the receiving antenna, respectively. The reception obstacle has become a social problem with the increase of high-rise buildings in recent years.

Various structures have been proposed as electromagnetic wave absorbers for absorbing electromagnetic waves. For example, an absorber for reflecting, absorbing, and transmitting an incoming electromagnetic wave, and a reflecting material for reflecting an incoming electromagnetic wave have been proposed. A λ / 4 type electromagnetic wave absorber having a configuration arranged at a distance corresponding to １ ／ of the wavelength of the electromagnetic wave to be absorbed is compared with a widely known electromagnetic wave absorber using a magnetic material such as ferrite. Thus, it has the advantage of being lightweight and inexpensive to manufacture. In addition, by using a member having light transmissivity, it is also possible to apply to a window of a building.

In a λ / 4 type electromagnetic wave absorber in which the space between the absorber and the reflector is filled with air, the absorber is used to absorb a relatively low-frequency electromagnetic wave in the VHF band (for example, about 100 MHz). And the reflector must be separated by about 75 cm, which is disadvantageous in that it is too thick to be attached to a window or a wall of a building. Therefore, by disposing a conductive coating coated in a stripe or lattice shape between the absorber and the reflector of the λ / 4 type electromagnetic wave absorber,
A technique for increasing the effective relative permittivity between the absorber and the reflector has also been proposed (see Japanese Patent Application Laid-Open No. 10-275997). According to the above technique, a λ / 4 type electromagnetic wave absorber that absorbs electromagnetic waves in the VHF band can be realized with a thickness of about 10 cm.

[0005]

However, λ / 4
The electromagnetic wave absorber is reflected by the reflector and transmitted through the absorber, including the configuration in which the striped or lattice-shaped conductive coating is disposed between the absorber and the reflector as described above, and is emitted. Since the electromagnetic wave uses the fact that it has an opposite phase to the electromagnetic wave reflected and emitted by the absorber, its absorption characteristics are limited to electromagnetic waves within a very narrow frequency band centered on the opposite phase frequency. Shows the property of absorbing at a high absorption rate. Therefore, there is a problem that electromagnetic waves cannot be absorbed over a wide frequency band.

[0006] The present invention has been made in view of the above facts, and has as its object to obtain an electromagnetic wave absorber capable of realizing a wider and thinner electromagnetic wave absorption band.

[0007]

Means for Solving the Problems To achieve the above object, the electromagnetic wave absorber according to the first aspect of the present invention is arranged along a predetermined direction, and reflects a part of the arriving electromagnetic wave to each other to reflect another part. A plurality of resistance members transmitting the portion, disposed at a distance in the predetermined direction with respect to the plurality of resistance members,
A reflection member for reflecting the arriving electromagnetic wave; and a reflection member provided at at least one position between the plurality of resistance members and between the reflection member and the specific resistance member, and intersects the arrangement direction of the plurality of resistance members and the reflection member. And a plurality of conductors arranged at intervals along the direction in which the conductors are arranged.

According to the first aspect of the invention, a plurality of resistance members that reflect a part of the arriving electromagnetic wave and transmit the other part are arranged along a predetermined direction, and the reflecting member that reflects the arriving electromagnetic wave is: A plurality of resistance members are arranged at a distance in a certain direction, and when an electromagnetic wave arrives from the side opposite to the side where the reflection member is arranged (resistance member side), the arriving electromagnetic wave moves in the electromagnetic wave arrival direction. Along the uppermost resistance member (hereinafter, referred to as the uppermost resistance member), a part is reflected by the uppermost resistance member, and another part is transmitted through the uppermost resistance member. .

The electromagnetic wave transmitted through the most upstream resistance member is incident on a resistance member (hereinafter, referred to as a downstream resistance member) located downstream of the most upstream resistance member along the arrival direction of the electromagnetic wave. A part is reflected by the downstream resistance member, and another part is transmitted through the downstream resistance member. As described above, the electromagnetic wave arriving from the resistance member side is partially reflected at the position where each resistance member is disposed, and the other part is transmitted. Further, the electromagnetic wave that has reached the position where the reflection member is disposed is reflected toward the resistance member. Therefore, the electromagnetic wave arriving from the resistance member side to the electromagnetic wave absorber according to the present invention is reflected at different positions (that is, the propagation paths have different lengths).
It is decomposed into one type (where n is the number of resistance members) of electromagnetic waves.

Here, the wavelength λ of an electromagnetic wave propagating through a certain medium is represented by f representing the frequency of the electromagnetic wave and ε (= ε _S
ε ₀ : ε _S is relative permittivity, ε ₀ is vacuum permittivity, and the magnetic permeability of the medium is μ (= μ _S μ ₀ : μ _S is relative magnetic permeability, μ ₀ is vacuum magnetic permeability). Since λ = 1 / f√ (εμ) (1), the wavelength λ changes according to the dielectric constant of the medium.

On the other hand, considering any two types of electromagnetic waves extracted from the (n + 1) types of electromagnetic waves, the phase of the electromagnetic wave having a shorter propagation path (referred to as a primary electromagnetic wave for convenience) out of the two types of electromagnetic waves, Regarding electromagnetic waves in a frequency band in which the phase of the longer electromagnetic wave (referred to as a secondary electromagnetic wave for the sake of convenience) is substantially opposite, the secondary electromagnetic wave having a substantially opposite phase is superimposed on the primary electromagnetic wave, so that λ / 4 The electromagnetic wave emitted from the electromagnetic wave absorber is attenuated and absorbed in the same manner as the type electromagnetic wave absorber. Then, an effective relative permittivity in a path through which only the secondary electromagnetic wave propagates (a path through which the primary electromagnetic wave does not propagate) (the effective relative permittivity is determined by parameters such as the length of the path and the dielectric constant of a medium on the path). It changes according to.

Therefore, in a configuration in which a plurality of resistance members and a reflection member are provided, for example, if the effective relative dielectric constants of a plurality of spaces defined by the plurality of resistance members and the reflection member are different from each other, n + 1 types of electromagnetic waves can be obtained. Number of combinations = (n +
1)! / [(N-1)! × 2], the electromagnetic waves are attenuated and absorbed in the same number of frequency bands as described above, so that the electromagnetic wave absorption band can be broadened. However, the thickness of the electromagnetic wave absorber is further increased by providing multiple resistance members. Do
There is a problem.

For this reason, according to the first aspect of the present invention, a plurality of conductors arranged at intervals along a direction intersecting the arrangement direction of the plurality of resistance members and the reflection member are formed between the plurality of resistance members and between the plurality of resistance members. It is provided at at least one position between the reflection member and the specific resistance member. When the plurality of conductors are arranged between the resistance members or between the reflection member and the resistance member, the effective relative permittivity ε between the resistance members or between the reflection member and the resistance member
_eff is the dielectric constant of the medium existing between the resistance member or between the reflection member and the resistance member, ε _a , ε _b , the width of the conductor along the direction intersecting the arrangement direction of the plurality of resistance members and the reflection member and Assuming that the interval is b and d and the thickness of the conductor along the arrangement direction of the plurality of resistance members and the reflection members is a, it is expressed by the following equation (2).

[0014]

(Equation 1)

As is apparent from the above equation (2), the effective relative permittivity ε between the resistive members or between the reflective member and the resistive members.
_eff (the permittivity between the resistive members or between the reflective member and the resistive member changes according to the effective relative permittivity ε _eff ) along a direction intersecting the arrangement direction of the plurality of resistive members and the reflective members. Conductor width b, spacing d along said intersecting direction,
And the thickness a of the conductor along the arrangement direction of the resistance member and the reflection member.

Therefore, according to the first aspect of the present invention, by appropriately setting the values of the thickness a of the conductor, the width b of the conductor, and the distance d, the location where a plurality of conductors are provided (between the resistance members) And the effective relative permittivity 反射_eff of at least one portion between the reflection member and the resistance member) is set to a value clearly larger than 1 (ε _eff
≫1) can be easily realized, so even when a plurality of resistance members are provided for the purpose of broadening the electromagnetic wave absorption band,
The thickness of the electromagnetic wave absorber can be reduced compared to the frequency band of the electromagnetic wave to be absorbed.

Further, by adjusting the values of the thickness a of the conductor, the width b of the conductor, and the interval d, it is easy to set the effective relative permittivity ε _eff at the location where a plurality of conductors are provided to a desired value. Since it can be realized, it is easy to configure the electromagnetic wave absorber so that the electromagnetic wave is attenuated and absorbed in a desired frequency band.

In the first aspect of the present invention, the difference between the effective relative dielectric constants of a plurality of sections defined by the plurality of resistance members and the reflection member is, for example, as described in the second aspect. The interval between members that define the section,
Presence or absence of a plurality of conductors in each section, positions of a plurality of conductors along an arrangement direction of a plurality of resistance members and reflection members, widths of the conductors along a direction intersecting the arrangement direction, directions intersecting the arrangement direction And at least one of the thicknesses of the conductors along the arrangement direction is different.

As is apparent from the above description, by providing a plurality of conductors according to the first aspect, as a method of making the effective relative permittivity of the plurality of sections different, the interval between members that partition each section is made different. In addition to the above-mentioned methods, various other methods will occur, and the effective relative dielectric constants of a plurality of sections can be made different from each other without causing a significant increase in the thickness of the electromagnetic wave absorber.

The electromagnetic wave absorption band of the electromagnetic wave absorber according to the present invention is determined by the effective relative permittivity of a plurality of sections defined by a plurality of resistance members and reflection members.
For this reason, as described in claim 3, the interval between the plurality of resistance members and the reflection member, the presence or absence of the plurality of conductors in each of the plurality of sections partitioned by the plurality of resistance members and the reflection member, the plurality of resistance members, Positions of the plurality of conductors along the arrangement direction of the reflection member, widths of the conductors along the direction intersecting the arrangement direction, gaps between the conductors along the direction intersecting the arrangement direction, and the conductors along the arrangement direction Is preferably set so that electromagnetic waves in a plurality of different frequency bands are absorbed. Thereby, the electromagnetic wave absorber according to the present invention can be configured such that electromagnetic waves in a plurality of different frequency bands (frequency bands to be absorbed) are respectively absorbed.

Incidentally, the permittivity (effective relative permittivity 率_eff obtained by the equation (2)) obtained by arranging a plurality of conductors in a fixed direction at an interval is described in detail in the arrangement direction of the plurality of conductors. The dielectric constant in the arrangement direction of the plurality of conductors acts on an electromagnetic wave whose polarization plane is in the arrangement direction of the plurality of conductors.

According to one aspect of the present invention, a plurality of conductors are arranged at intervals along a single direction intersecting the arrangement direction of a plurality of resistance members and reflection members. Although a configuration (a configuration in which conductors are arranged in a stripe shape) can be cited, in this configuration, the increase in the effective relative permittivity due to the provision of a plurality of conductors is caused by the fact that the direction of the polarization plane is substantially orthogonal to the single direction. Since it acts only on electromagnetic waves that are present, its absorption performance for electromagnetic waves with an indeterminate plane of polarization (for example, circularly polarized electromagnetic waves) is very low, and the absorption of electromagnetic waves whose direction of polarization is substantially the same as the single direction The band is greatly different from the absorption band of the electromagnetic wave in which the direction of the polarization plane is substantially orthogonal to the single direction.

Therefore, according to a fourth aspect of the present invention, in the first aspect of the present invention, the plurality of conductors are spaced apart along a first direction intersecting the arrangement direction of the plurality of resistance members and the reflection members. They are arranged and are arranged at intervals along a second direction that intersects the arrangement direction and the first direction.

In the fourth aspect of the present invention, the effective relative permittivity ε _eff in the first direction depends on the width and the interval of the conductors along the first direction (and the thickness of the conductors along the arrangement direction). And the effective relative permittivity ε _{eff in} the second direction.
Varies according to the width and spacing of the conductors along the second direction (and the thickness of the conductors along the arrangement direction). Therefore, by appropriately setting the width and spacing of the conductors in the first direction of the plurality of conductors and the width and spacing of the conductors in the second direction, the effective relative permittivity ε _eff and the The effective relative permittivity ε _eff in the second direction can be set to a desired value, and absorption of an electromagnetic wave over a desired wide frequency band is realized regardless of the direction of the plane of polarization of the electromagnetic wave. be able to.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1A shows an electromagnetic wave absorbing panel 10 as an electromagnetic wave absorber according to the present invention. The electromagnetic wave absorbing panel 10 has flat insulating substrates 12A, 12B and 14 made of an insulating material and arranged in parallel at a predetermined interval. The insulating substrates 12A, 12B, and 14 can be formed by selectively using an arbitrary material from various known insulating materials to form a flat plate.
Is required to have a light transmitting property (for example, when the electromagnetic wave absorbing panel 10 is used as a window of a building), for example, a material such as glass or a light transmitting vinyl or plastic is used. Can be configured.

Of the insulating substrate 14, the insulating substrate 12
A conductive film (reflection film) 18 is formed on the surfaces on the sides A and 12B. The conductivity (surface resistance) of the reflective film 18 is adjusted so that most of the arriving electromagnetic waves are reflected. The sheet resistance suitable for the reflection film 18 is 1 μΩ to 30 μm per unit area.
Ω, more preferably 10 mΩ per unit area.
Although it is about 20 Ω, if the electromagnetic wave absorbing panel 10 is not required to have optical transparency, the sheet resistance can be made smaller, and the reflection ratio of the incoming electromagnetic wave can be made higher.

On the other hand, since the insulating substrates 12A and 12B have the same configuration, they will be hereinafter collectively referred to as the insulating substrate 12. On the insulating substrate 14 side of the insulating substrate 12, the insulating substrate 1 is separated from the insulating substrate 12 by a predetermined distance.
In parallel with 2, an insulating substrate 60 made of a known insulating material such as glass is arranged. As shown in FIG. 1B, a conductive film (resistive film) 16, an insulating film layer 62, and a divided conductor layer 64 are arranged in the gap between the insulating substrates 12 and 60 in this order from the insulating substrate 12 side. These insulating substrates 12 and 60, the resistive film 16, the insulating film layer 62, and the divided conductor layer 64 are integrated in the same manner as a so-called laminated glass.

The resistance film 16 has a conductivity (resistance per unit area: sheet resistance) so that when an electromagnetic wave arrives, it absorbs a part of the electromagnetic wave, reflects another part, and transmits the other part. Has been adjusted. The sheet resistance suitable for the resistance film 16 is about 50Ω to 3000Ω per unit area, and more preferably about 200Ω to 1500Ω per unit area.

As the divided conductor layer 64, for example, the configuration shown in FIG. 2A or the configuration shown in FIG. 2B can be adopted. The divided conductor layer 64 shown in FIG.
Is a flat and long shape having a certain thickness, and the longitudinal direction is the resistance film 1.
1 and a certain direction orthogonal to the direction in which the reflection film 18 is arranged (FIG. 1).
2, a plurality of conductive films 66 arranged along a direction perpendicular to the plane of FIG.
Are perpendicular to the width direction (the direction of arrow B in FIGS. 1 and 2, the direction in which the resistive film 16 and the reflective film 18 are arranged, and the second direction, respectively).
And the conductive films 66 adjacent to each other in the direction (direction). Note that the width b of the conductive film 66 is preferably b ≦ 50 cm.

The divided conductor layer 64 shown in FIG.
A plurality of flat rectangular conductive films 66 having a constant thickness are arranged in a matrix along the first direction and the second direction, and each of the conductive films 66 is spaced apart from the conductive film 66 adjacent in the first direction and the second direction. They are arranged so as to be separated by d. Note that FIG.
The conductive film 66 shown in FIGS. 2A and 2B corresponds to the conductor according to the present invention, and in particular, the conductive film 66 shown in FIG.
Corresponds to the conductor according to claim 4. Note that FIG.
In (B), the width b _{1 of the} conductive film 66 along the first direction is shown.
Is preferably b ₁ ≦ 50 cm, and the width b _{2 of the} conductive film 66 along the second direction is also preferably b ₂ ≦ 50 cm.

The sheet resistance suitable for the conductive film 66 is about 1 μΩ to 40 Ω per unit area, and more preferably about 10 mΩ to 20 Ω per unit area. The insulation resistance value Rd of the insulating substrate on which the conductive film 66 is formed is Rd ≧
30 kΩ.

As shown in FIG. 2B, a conductor (conductive film 6) is used.
In the configuration in which 6) are arranged two-dimensionally, the two directions (first direction and second direction) as the arrangement direction of the conductors do not necessarily need to be orthogonal, and the two directions may be directions that intersect each other. .

Further, in the electromagnetic wave absorbing panel 10 according to the present embodiment, between the insulating substrate 60 integrated with the insulating substrate 12A and the insulating substrate 12B, and between the insulating substrate 12B and the insulating substrate 12B.
The space between the insulating substrate 60 integrated with B and the reflective film 18 is filled with dry air. Instead, a resin material is filled in, or an insulating material or a ferroelectric material is provided. Is also good.

The resistance film 16, the reflection film 18, and the conductive film 66 can be formed by using any of various known conductive materials. In the case where transparency is required, for example, a transparent conductive film mainly containing tin oxide (SnO ₂ ), a transparent conductive film mainly containing indium oxide (In ₂ O ₃ ), and titanium oxide ( A transparent conductive film mainly composed of TiO _x : x = 1 to 2.5), titanium nitride (TiN _x : x =
0.5 to 2) as a main component, a transparent conductive film, Ag, Au,
A metal film containing Cu or Al as a main component is preferable. Since the transparent conductive film and the metal film as described above have a property of reflecting near-infrared light included in sunlight and having a low radiation amount of heat rays, an electromagnetic wave formed using the above-described material is used. By using the absorbing panel 10 for a window of a building, energy saving of indoor cooling and heating can be realized.

Further, the electromagnetic wave absorbing panel 10 according to the present embodiment has the resistance film 16 integrated with the insulating substrate 12A.
(Hereinafter referred to as a first resistive film 16 for convenience) and a distance between the resistive film 16 (hereinafter referred to as a second resistive film 16 for convenience) integrated with the insulating substrate 12B and the second resistive film The distance between the reflective film 16 and the reflective film 18 is different. This is the first
The purpose is to make the effective relative permittivity between the second resistive film 16 and the second resistive film 16 different from the effective relative permittivity between the second resistive film 16 and the reflective film 18. Thus, the divided conductor layer 64 (hereinafter, referred to as a first divided conductor layer 64 for convenience) integrated with the insulating substrate 12A and the divided conductor layer 64 (hereinafter, referred to as the first divided conductor layer 64) integrated with the insulating substrate 12B. For convenience, it is referred to as a second divided conductor layer 64).
The width b of the conductive film 66 along the direction, the interval d, and the resistance film 1
6 and the distance between the resistive film and the reflective film (the first resistive film 16 and the second resistive film 1).
6 and a distance between the second resistive film 16 and the reflective film 18). By providing the divided conductor layer 64 in this manner, the first resistance film 16 and the second
The effective relative permittivity between the first resistive film 16 and the second resistive film 16
It can be easily realized that the effective relative permittivity is different from that between the reflective film 18 and the reflective film 18.

The operation of the present embodiment will be described. The electromagnetic wave absorbing panel 10 is disposed, for example, in a window of a building. It should be noted that the electromagnetic wave absorbing panel 10 to be provided has the divided conductor layer 6
In the case of the electromagnetic wave absorbing panel 10 employing the configuration shown in FIG. 2A (the divided conductive layer 64 made of the long conductive film 66) as the fourth example, the second direction (the arrangement direction of the conductive film 66) is as follows.
A direction substantially matching the direction of the plane of polarization of the electromagnetic wave arriving at the building (for example, when a vertically polarized electromagnetic wave arrives,
The direction in which the vertical direction in Fig. 1 matches the vertical direction of the building)
And the electromagnetic wave comes from the insulating substrate 12A side.

When an electromagnetic wave arrives at a building in a state where the electromagnetic wave absorbing panel 10 is disposed on the building as described above, the incoming electromagnetic wave (electromagnetic wave E ₀ shown in FIG. 3) as shown in FIG.
Is transmitted through the insulating substrate 12A and is incident on the first resistive film 16, a part of which is reflected by the first resistive film 16 to the outside of the electromagnetic wave absorbing panel 10 as a primary emission electromagnetic wave _Er01 , and a part is The remainder is absorbed by the first resistive film 16 and the remainder is transmitted through the first resistive film 16 and emitted as electromagnetic waves _Et11 toward the insulating substrate 12B.

The electromagnetic wave _{Et 11} passes through the first divided conductive layer 64 and is incident on the insulating substrate 12B, passes through the insulating substrate 12B and is incident on the second resistance film 16. Then, a part of the first resistance film 16 is formed by the second resistance film 16.
Is reflected to the side as electromagnetic wave E _r11 , and partially
And the rest is absorbed by the second resistive film 1.
6 and is emitted to the reflection film 18 side as an electromagnetic wave _Et21 .

The first resistive film 16 is formed by the second resistive film 16.
The electromagnetic wave E _r11 reflected to the side is applied to the first divided conductor layer 6.
4 again, is incident on the first resistive film 16, a part is transmitted through the first resistive film 16, is emitted out of the electromagnetic wave absorbing panel 10 as the secondary emission electromagnetic wave E _r02 , and a part is the second emission electromagnetic wave E _r02 . The light is absorbed by the first resistive film 16, and the rest is reflected by the first resistive film 16 toward the second resistive film 16.

On the other hand, the electromagnetic wave _{Et 21} transmitted through the second resistance film 16 transmits through the second divided conductor layer 64 and is reflected by the reflection film 1.
8, most of the light is reflected by the reflection film 18, passes through the second divided conductor layer 64 again, and receives the electromagnetic wave E.
_{The light} is incident on the second resistance film 16 as _r21 . A part of the electromagnetic wave E _r21 incident on the second resistance film 16 passes through the second resistance film 16 and is emitted to the first resistance film 16 side as an electromagnetic wave E _r12 , and a part of the resistance wave 16 And the rest is reflected by the resistive film 16 toward the reflective film 18 and emitted.

The second resistive film 16 transmits through the first resistive film
Electromagnetic wave E emitted to the resistance film 16 side _r12Is the first split
The light passes through the conductor layer 64 and is incident on the first resistance film 16,
Part of the electromagnetic wave absorbing panel 10 is transmitted through the first resistive film 16.
Tertiary emission electromagnetic wave E out_r03Injected as
Portion is absorbed by the first resistive film 16 and the rest is
The light is reflected by the resistance film 16 toward the second resistance film 16.

By repeating the above phenomenon, the electromagnetic wave arriving at the electromagnetic wave absorbing panel 10 is changed from the primary emission electromagnetic wave to
Since (theoretically n _MAX = ∞) n _MAX order electromagnetic wave is divided into emitted from the electromagnetic wave absorption panel 10, the reflection coefficient of the electromagnetic wave absorbing panel 10 coming from the resistance film 16 is formed the insulating substrate 12 side Γ

[0043]

(Equation 2)

Is as follows.

Here, the electromagnetic waves incident on the first resistive film 16 and the second resistive film 16 are partially absorbed by the resistive film 16 so that they pass through the resistive film 16 or pass through the resistive film 16.
The electric field intensity of the electromagnetic wave reflected and emitted by the light source is reduced. Since the number of times that the order n of the n-th emitted electromagnetic wave is incident on the resistive film 16 increases as the value of the order n increases, the value of the order n is large, although it depends on the value of the absorptivity α of the electromagnetic wave in the resistive film 16. Higher-order emitted electromagnetic waves (e.g., emitted electromagnetic waves with n ≧ 3) can be neglected because the electric field intensity becomes very small.

Further, the electromagnetic wave absorbing panel 10 according to the present embodiment is provided with a plurality of resistive films 16, the distance between the first resistive film 16 and the second resistive film 16, and the second resistive film 1.
6 and the reflection film 18 are different in distance, so that the primary emission electromagnetic wave E _r01 reflected and emitted by the first resistance film 16 is emitted.
And the secondary emission electromagnetic wave E _r02 reflected and emitted by the second resistance film 16 has a frequency f _{1 of} an electromagnetic wave having substantially the opposite phase.
Primary emission electromagnetic wave E reflected and emitted by the resistive film 16 of FIG.
_r01 and a tertiary emission electromagnetic wave E _r03 reflected and emitted by the reflective film 18 have a frequency f _{2 of} an electromagnetic wave having substantially opposite phase, and a primary emission electromagnetic wave E _r01 reflected and emitted by the first resistive film 16. The frequency f ₃ of the electromagnetic wave that is substantially opposite in phase to the tertiary emission electromagnetic wave E _r03 reflected and emitted by the reflection film 18 is different from each other, and the frequency f ₃ of each of the center frequencies f ₁ , f ₂ , and f ₃ is different. Since attenuation and absorption occur, the band of the electromagnetic wave absorption band can be widened.

Further, in the electromagnetic wave absorbing panel 10 according to the present embodiment, between the first resistance film 16 and the second resistance film 16,
Since the divided conductor layers 64 are provided between the second resistive film 16 and the reflective film 18, respectively, between the first resistive film 16 and the second resistive film 16 and between the first resistive film 16 and the second resistive film 16. The arrangement direction of the conductive film 66 between the film 16 and the reflective film 18 (the divided conductive layer 64
2A is formed of a long conductive film 66 shown in FIG. 2A, the divided conductor layer 64 in the second direction is formed of a rectangular conductive film 66 shown in FIG. If there is first
Direction and the second direction) have a very high value.

That is, when an electromagnetic wave arrives at the divided conductor layer 64, a large number of polarizations are generated in the individual conductive films 66, and the electric field inside the individual conductive films 66 becomes zero with the occurrence of the polarization. An anti-polarization electric field is induced. Further, when an electromagnetic wave arrives at the divided conductor layer 64, charges move in the individual conductive films 66 along the direction of the plane of polarization of the incoming electromagnetic wave, and the movement of the charges is caused by conduction along the direction of the plane of polarization. Since the film stops at the end of the film 66, charges having different polarities are accumulated at the ends of the adjacent conductive films 66 with a gap therebetween. The effective relative permittivity between the first resistive film 16 and the second resistive film 16 and the effective relative permittivity between the second resistive film 16 and the reflective film 18 are determined by the above-described anti-polarization electric field, It is increased by Coulomb interaction caused by accumulation of charges of opposite polarity at the ends of adjacent conductive films 66.

Also, in the electromagnetic wave absorbing panel 10 according to the present embodiment, the thickness w of the insulating film layer 62 (ie, the distance w between the resistive film 16 and the conductive film 66) is determined by the distance between the conductive films 66 of the divided conductive layer 64. d, the Coulomb interaction occurs between the resistive film 16 and the conductive film 66 with the arrival of the electromagnetic wave, and the effective relative permittivity between the resistive film 16 and the reflective film 18 is very high. Value.

Accordingly, the first resistive film 16 and the second resistive film 16
Between the resistive films 16 and between the second resistive film 16 and the reflective film 18
The wavelength of the electromagnetic wave that propagates back and forth through the
Always shorter (electromagnetic wave E_tnIs the square of the effective dielectric constant
Because it is inversely proportional to the root).
Wavenumber band (center frequency f₁, F_Two, F_ThreeEach frequency band)
The distance between the insulating substrate 12A and the insulating substrate 14 is smaller than that of FIG.
Always smaller. Therefore, the electromagnetic wave absorption according to the present embodiment
The panel 10 has a wide frequency band (center frequency f ₁, F_Two,
f_ThreeSufficient electromagnetic wave absorption for each frequency band
Performance, and compared to the frequency band to be absorbed.
The distance between the insulating substrates 12A and 14 is extremely small.
That is, the thickness can be significantly reduced.

As the divided conductor layer 64, FIG.
As shown in (A), when the configuration in which the long conductive films 66 are arranged is adopted, the direction of the polarization plane of the electromagnetic wave absorbed by the electromagnetic wave absorbing panel 10 is the second direction (the conductive film 66).
In the case where a configuration in which rectangular conductive films 66 are arranged in a matrix as the divided conductive layers 64 is adopted as the divided conductive layers 64, as shown in FIG. Thus, the electromagnetic wave arriving at the electromagnetic wave absorbing panel 10 can be absorbed at a high absorption rate regardless of the direction of the polarization plane of the electromagnetic wave.

Further, as described above, if the electromagnetic wave absorbing panel 10 is made of a member having a light transmitting property, the electromagnetic wave absorbing panel 10 having a light transmitting property can be obtained. It is also possible to dispose them at a site where light transmission is required.

The effective relative permittivity between the first resistive film 16 and the second resistive film 16 when an electromagnetic wave arrives, and the effective relative permittivity between the second resistive film 16 and the reflective film 18 The rate is
The distance w increases as the distance w between the resistive film 16 and the conductive film 66 decreases. However, depending on the electric field intensity of the electric field generated with the arrival of the electromagnetic wave, the distance between the first resistive film 16 and the conductive film 66 and the 2 between the resistive film 16 and the conductive film 66, and a conductive current may flow. For this reason,
The distance w between the resistive film 16 and the conductive film 66 should be as small as possible and not less than the minimum distance that can prevent the occurrence of dielectric breakdown between the resistive film 16 and the conductive film 66 in consideration of the intensity of the incoming electromagnetic wave. It is desirable to make the electromagnetic wave absorbing panel 10 thinner.

In the above embodiment, if a ferroelectric film layer made of a ferroelectric material is provided instead of the insulating film layer 62 made of a known insulating material,
This is preferable because the effective relative dielectric constant between the first and second reflective films 6 and 18 can be further increased, and the electromagnetic wave absorbing panel 10 can be further reduced in thickness.

In the above, an example in which the divided conductor layers 64 are provided between the first resistance layer 16 and the second resistance layer 16 and between the second resistance layer 16 and the reflection layer 18 has been described. However, the present invention is not limited to this, and as an example, FIG.
As shown in FIG. 4A, a divided conductor layer may be provided only between the first resistance layer 16 and the second resistance layer 16, or as an example, as shown in FIG. May be provided only between the resistive layer 16 and the reflective layer 18. Also, the number of resistance layers is not limited to “2”, and it goes without saying that three or more resistance layers may be provided.

In the above description, a configuration in which the resistive film 16, the insulating film layer 62, and the divided conductor layer 64 are sequentially formed in the gap between the insulating substrates 12, 60 has been described as an example. However, the present invention is not limited to this. Instead, a configuration in which the insulating substrate 60 is omitted by forming the divided conductor layer 64 on the insulating film layer 62 by printing the divided conductor layer 64 on the insulating film layer 62 is adopted. Is also possible.

[0057]

As described above, according to the present invention, a plurality of resistance members for reflecting a part of an incoming electromagnetic wave and transmitting the other part are arranged along a certain direction, A plurality of conductors arranged at a distance in a certain direction and arranged at intervals along a direction intersecting the arrangement direction of the plurality of resistance members and the reflection member, between the plurality of resistance members and the reflection member. Since it is provided at at least one position between the specific resistance members, it has an excellent effect that the electromagnetic wave absorption band can be widened and thinned.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view of an electromagnetic wave absorbing panel according to the embodiment, and FIG. 1B is a partially enlarged view of FIG.

FIG. 2 is a plan view illustrating an example of a configuration of a divided conductor layer.

FIG. 3 is a conceptual diagram illustrating the principle of electromagnetic wave absorption by the electromagnetic wave absorbing panel according to the embodiment.

FIGS. 4A and 4B are schematic diagrams showing another configuration example of the electromagnetic wave absorbing panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electromagnetic wave absorption panel 16 Resistive film 18 Reflective film 64 Split conductive layer 66 Conductive film

Continuing on the front page (72) Inventor Kenichi Harakawa 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside the Research Institute of Takenaka Corporation (72) Inventor Toshio Saito 1-5-1, Otsuka 1, Inzai City, Chiba Pref. Takenaka Corporation Technical Research Institute (72) Inventor Kenji Murata 2-1-7 Coast, Minato-ku, Tokyo Nippon Sheet Glass Tokyo Building Nippon Sheet Glass Co., Ltd. (72) Inventor Motoyasu Togashi 1-11-1-11, Shiba, Minato-ku, Tokyo Nippon Sheet Glass Environment Amenity Co., Ltd. (72) Inventor Yasushi Hoshino 1-11-11 Shiba, Minato-ku, Tokyo F-term (reference) 5E321 AA33 AA41 AA44 BB21 BB23 BB25 BB41 BB51 GG11 5J020 EA03 EA05 EA05 EA07 EA10

Claims (4)

[Claims] 1. A plurality of resistance members arranged along a certain direction, each reflecting a part of an arriving electromagnetic wave and transmitting the other part, and a distance in the certain direction with respect to the plurality of resistance members. A reflection member that is disposed at a distance and reflects an incoming electromagnetic wave; and a reflection member that is provided between the plurality of resistance members and at least one location between the reflection member and a specific resistance member, wherein the plurality of resistance members and the reflection member are provided. And a plurality of conductors arranged at intervals along a direction intersecting the arrangement direction of the electromagnetic wave absorber. 2. An interval between members that define each section, and the presence or absence of the plurality of conductors in each section, so that effective resistances of a plurality of sections defined by the plurality of resistance members and the reflection member are different from each other. Positions of the plurality of conductors along the arrangement direction of the plurality of resistance members and the reflection member,
At least one of a width of the conductor along a direction intersecting the arrangement direction, a gap between the conductors along a direction intersecting the arrangement direction, and a thickness of the conductor along the arrangement direction
The electromagnetic wave absorber according to claim 1, wherein the two are different. 3. An interval between the plurality of resistance members and the reflection member, and a plurality of sections defined by the plurality of resistance members and the reflection member such that electromagnetic waves in a plurality of different frequency bands are absorbed. The presence or absence of the plurality of conductors in each, the position of the plurality of conductors along the arrangement direction of the plurality of resistance members and the reflection member, the width of the conductors along a direction intersecting the arrangement direction, the arrangement direction and 2. The electromagnetic wave absorber according to claim 1, wherein at least one of a gap between the conductors along the intersecting direction and a thickness of the conductor along the arrangement direction is set. 3. 4. The plurality of conductors are arranged at intervals along a first direction intersecting the arrangement direction of the plurality of resistance members and the reflection member, and are arranged in the arrangement direction and the first direction. The electromagnetic wave absorber according to claim 1, wherein the electromagnetic wave absorbers are arranged at intervals along a second direction intersecting with each other.