JPH11204984A - Frequency selective electromagnetic wave shield material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shield a plurality of electromagnetic waves simultaneously without requiring any grounding by specifying the thickness of a spacer for a plurality of resonant frequency selective electromagnetic wave shielding planar bodies and the electric length of an electromagnetic wave having a frequency to be shielded. SOLUTION: When a resonant frequency selective electromagnetic wave shielding planar body having a capacitor and an inductor is directed vertically to the advancing direction of an electromagnetic wave, a unit 102, 102', 112, 112' of a conductive pattern formed on the surface of an insulating basic material 101, 111 becomes an inductor and a broken conductivity part 103, 113 becomes a capacitor. Resonance frequency preferably matches the frequency of an electromagnetic wave to be shielded. The conductive pattern 102, 102', 112, 112' has a profile, dimensions and a line width dependent on the frequency to be shielded, a desired shielding power, and the like, and a spacer for keeping a thickness of 1/160 of the electric length of lowest frequency electromagnetic wave or above with accuracy of ±10% is preferably employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding material for reflecting electromagnetic waves in a specific range of frequencies, and more particularly to an electromagnetic wave shielding material capable of reflecting a plurality of electromagnetic waves having different frequencies.

[0002]

2. Description of the Related Art In recent years, with the development of communication systems such as mobile phones and wireless LANs, it has become necessary to protect office information and prevent communication crosstalk. In order to suppress the intrusion and leakage of unnecessary electromagnetic waves and maintain an environment in which communication can be performed comfortably, it is common practice to surround buildings and the like with a grounded conductive material to block internal and external electromagnetic waves.

[0003] Generally used metal nets, metal foils, metal deposition products, and I used for transparent parts such as windows.
In the case of an electromagnetic wave shielding material that requires grounding using a transparent conductive film such as TO, when a shielding material is applied to a wall surface or the like, the gap between seams between the shielding materials needs to be controlled to be equal to or less than the wavelength of the electromagnetic wave. This is because if this gap exceeds the wavelength of the electromagnetic wave, the shielding power is extremely reduced. Further, it is necessary to make the electromagnetic shielding materials electrically conductive.

For example, when an electromagnetic wave shielding material is provided on a wall surface, an operation is performed in which the ends of the net-shaped electromagnetic wave shielding material are joined in a state of being overlapped, and a skin material is covered from above. In the case where an electromagnetic wave shielding material is provided in the window portion, an operation is performed in which a shield glass made conductive by ITO or the like is inserted into a special window frame in which connection terminals are previously provided to electrically conduct with an adjacent shielding material. Such a shield construction is time-consuming and enormous.

On the other hand, a resonance type frequency selective electromagnetic wave shielding material is a material in which a plurality of conductive patterns are regularly gathered on the surface of an insulating base material. And each conductive part is not electrically conducting with each other. Such materials include the shape of the conductive portions, the relative positions between the conductive portions,
LC resonance occurs for electromagnetic waves in a specific range of frequencies determined by the material constituting the conductive portion and the electrical properties of the space in which the conductive portion exists. As a result, only specific electromagnetic waves are selectively reflected, and other electromagnetic waves are transmitted.

For example, Japanese Patent Application Laid-Open No. 8-330783 discloses that
An electromagnetic wave that shields PHS radio waves by arranging a cross, X-shaped, or Y-shaped metal shape that combines conductive lines about half the wavelength of the PHS frequency on a transparent sheet at an interval of about half the PHS frequency. Shield material is described. 199
In the September 2007 (Kanto) Annual Meeting of the Architectural Institute of Japan,
An electromagnetic wave shielding material for a PHS frequency in which a receiving end short-circuited dipole antenna is printed on a glass surface by firing is described. Also, Japanese Patent Application No. 9-22675 describes an electromagnetic wave shielding material having a conductive loop pattern composed of a plurality of conductive patterns regularly arranged on an insulating base material.

[0007] Such a resonance type electromagnetic wave shielding material does not require electrical conduction between the electromagnetic wave shielding materials, and is capable of shielding electromagnetic waves even when a small gap is formed between the shielding materials when it is provided on a wall of a building or the like. Does not drop.

However, since the resonance type electromagnetic wave shielding material has frequency selectivity, the frequency band that can be cut off is narrow, and it is difficult to simultaneously cut off a plurality of electromagnetic waves having different frequencies. For example, PHS (1.9 GHz) electromagnetic waves and medium-speed wireless LANs (2.
(45 GHz) It is difficult to block electromagnetic waves at the same time with a conventional resonance type electromagnetic wave shielding material.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems. It is an object of the present invention to perform electromagnetic wave shielding work without the need for grounding, and to reduce a plurality of electromagnetic waves having different frequencies. An object of the present invention is to provide a resonance type electromagnetic wave shielding material which can be cut off at the same time.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided an electromagnetic wave shielding material in which a plurality of resonance type frequency-selective electromagnetic wave shielding sheet members are stacked via a spacer material, and the thickness of the spacer material is to be shielded. The present invention provides an electromagnetic wave shielding material having an electric length of 1/160 or more of an electromagnetic wave having a frequency to be used.

The resonance-type frequency-selective electromagnetic wave blocking sheet has a pattern formed of a conductive thin film forming a capacitor and an inductor, resonates with an electromagnetic wave, reflects only an electromagnetic wave in a resonance region, and forms a non-resonance region. Refers to a planar body that has the property of transmitting electromagnetic waves. In general, a resonance-type frequency-selective electromagnetic wave shielding sheet is an electromagnetic wave shielding material in which a plurality of conductive patterns are regularly gathered on the surface of an insulating base material.

In the resonance type frequency-selective electromagnetic wave blocking sheet used in the present invention, the capacitance and the inductor are connected in series. Generally, one unit of a conductive pattern regularly arranged at regular intervals while maintaining electrical insulation from each other has a possibility of functioning as an inductor. Among these, those that are close to each other have a possibility of forming a capacitance unit between them.

FIGS. 1A and 1B are schematic cross-sectional views showing an example of a resonance-type frequency-selective electromagnetic wave shielding sheet having a capacitor and an inductor formed thereon. 1A and 1B are parallel to the electric field direction E of the electromagnetic wave. As described above, when the resonance-type frequency-selective electromagnetic wave shielding sheet is oriented perpendicular to the traveling direction of the electromagnetic wave, one unit of the conductive pattern provided on the surface of the insulating base materials 101 and 111 is used. 102, 10
2 ′, 112 and 112 ′ become inductors, and the portions 103 and 113 where the conductivity is interrupted become capacitors.

One unit 102, 102 ', 1 of the conductive pattern
The properties of the inductors 12, 112 'as the inductors in the direction parallel to the electric field direction E are larger and thinner (the smaller the cross-sectional area taken along a plane perpendicular to the electric field direction), the stronger. In addition, the portions 103 where the conductivity is interrupted, 1
The capacity of the capacitor 13 is such that its dimension in the direction parallel to the electric field direction E is smaller and the cross-sectional area of one unit 102, 102 ', 112, 112' of the conductive pattern cut by a plane perpendicular to the electric field direction. The larger is the stronger.

The resonance frequency f _rs of the series element of the capacitor and the inductor is expressed by the following equation using the size C of the capacitor and the size L of the inductor.

F _rs = 1 / {2π (LC) ^1/2 }

A resonance-type frequency-selective electromagnetic wave blocking sheet having a series circuit of a capacitor and an inductor that resonates at a frequency f in a space where an electromagnetic wave of a frequency f travels is moved to an electric field direction E.
Parallel to (perpendicular to the direction of the electromagnetic wave)
The impedance at the place where this sheet is placed is almost 0Ω
, And the electromagnetic waves traveling at that location are reflected.

That is, if the shape and arrangement of the conductive pattern formed on the surface of the resonance-type frequency-selective electromagnetic wave shielding sheet is appropriately selected to adjust the strength as a capacitor and an inductor, Can be arbitrarily adjusted.

It is preferable that the resonance frequency of the resonance-type frequency-selective electromagnetic-wave-blocking planar body is close to, and more preferably equal to, the frequency of the electromagnetic wave to be shielded. This is because the shielding ability of the obtained frequency selective electromagnetic wave shielding material is increased.

Specifically, the resonance type frequency-selective electromagnetic wave shielding sheet is composed of an insulating base material and a plurality of conductive patterns regularly arranged on one plane or on both front and back surfaces. be able to. PET film as the insulating substrate,
Polypropylene film, acrylic board, vinyl chloride board,
A urea resin plate, a glass plate, a gypsum board, a calcical plate, a paper and a wooden plate can be used. It is preferable to use an organic resin film such as a PET film. This is because it has excellent insulation properties and strength and has flexibility.

The conductive pattern is formed by using a conductive material, generally a metal having a current-carrying ability. In order to provide an electromagnetic shielding material having excellent shielding performance, it is preferable to use a conductive material having a small volume resistivity. If the volume resistivity of the conductive material exceeds, for example, 10 Ωcm, 20 d
It becomes difficult to exhibit shielding performance exceeding B.

For example, iron, aluminum, copper, gold, silver,
Conductive metals such as tantalum, chromium and nickel, I
Conductive metalized materials such as TO and tin oxide can be used. A conductive ink such as a silver paste, a copper paste, a nickel paste, and a copper-silver plating paste may be used.

The conductive pattern can be formed on the resin film by various methods. For example, there are a method of printing using a conductive ink, a method of selectively removing a metal film laminated on a resin film to leave a conductive pattern, and the like.

A preferred method is to first form a conductive metal thin film layer on the entire surface of a resin film and partially remove the metal thin film by an appropriate method (eg, lithography method) to form a pattern. It is.

The method for forming the conductive metal thin film layer on the resin film may be a conventionally known method. For example, a method of laminating a conductive metal foil, a method of depositing a metal thin film, sputtering, or an electroless plating method are generally used. Preferably, a metal thin film deposition method (specifically, vacuum deposition) is used.

The shape, size, line width, and the like of the conductive pattern are appropriately determined depending on the frequency to be shielded, the desired breaking force, and the like. Generally, when one insulated conductive pattern is taken as one unit, the higher the frequency to be shielded, the smaller the size of one unit of the conductive pattern becomes, and the lower the frequency to be shielded, the smaller the conductive pattern becomes one unit. Becomes larger.

One unit of the conductive pattern is usually constituted by combining a plurality of finite straight lines. In that case, it is preferable that the length of the line constituting one unit of the conductive pattern is smaller than the wavelength of the electromagnetic wave to be shielded. This is because the resonance frequency can be easily controlled, and the frequency to be shielded can be matched with the resonance frequency.

The greater the thickness of the conductive pattern, the lower the electrical resistance and the easier it is to ensure the breaking performance. However, if the thickness is too large, the surface of the obtained electromagnetic wave shielding material becomes uneven, so that handling becomes inconvenient. Generally, the smaller the volume resistivity of the conductive material used, the better the blocking performance can be provided with a thinner thickness. For example, when the volume resistivity is small, such as a conductive pattern formed by evaporating aluminum, 30 n
A thickness of at least m is sufficient, but a thickness of several μm or more is required when the volume resistivity is large, such as a conductive pattern formed of a metal oxide or a conductive ink.

The arrangement of the conductive pattern is appropriately determined depending on the frequency to be shielded, the desired breaking force, and the like. For example, an equally-spaced lattice-like or echelon-like arrangement can be used.

The conductive patterns may be made to approach each other two-dimensionally as shown in FIG. 2A, distance d, and FIG.
As shown in FIG. For example, when the conductive patterns as shown in FIG. 2B are regularly formed on both surfaces of the resin film, there are two surfaces on which the mutually insulated conductive patterns are regularly arranged. Looks like. However, since the conductive patterns on both surfaces resonate to shield electromagnetic waves of a specific frequency, in the present invention, these are considered integrally as a resonance-type frequency-selective electromagnetic wave blocking sheet.

Specifically, the arrangement of the conductive patterns exemplified in Japanese Patent Application No. 9-22675 may be used. When the formed electromagnetic wave shielding material is viewed from a direction perpendicular to the plane thereof, it is preferable that the pattern made of the conductive thin film forms a grid at equal intervals. When making a transparent shielding material using a translucent material for the insulating base material and the spacer,
This is because a shield material having excellent transparency can be obtained.

The spacer material used in the present invention is not particularly limited as long as it is an insulator capable of substantially maintaining a predetermined thickness. Examples of the material used as the spacer material in the present invention include a plastic plate such as an acrylic plate and vinyl chloride, a thermosetting resin plate such as a urea resin plate, a glass, a gypsum board, a slate plate, an asbestos pearlite plate and calcium carbonate. There are inorganic building materials such as boards. If a transparent acrylic plate or glass is used, a transparent shielding material can be obtained.

The predetermined thickness is not less than 1/160 of the electrical length of the electromagnetic wave of the frequency to be shielded, preferably the lowest frequency of the electromagnetic wave to be shielded. A spacer material that can maintain its thickness with an accuracy of ± 10% is particularly preferable.

Here, the electromagnetic wave of the frequency to be shielded may be single or plural.

When there are a plurality of electromagnetic waves of the frequency to be shielded, a comparison between two resonance-type frequency-selective electromagnetic-wave-blocking planar bodies having close resonance frequencies indicates that the higher resonance frequency and the lower resonance frequency are different. Are used. More than one-fifth of the resonance frequency of the higher resonance frequency is used.

Thus, a multi-frequency selective electromagnetic wave shielding material for selectively shielding a plurality of frequencies can be obtained.

When the electromagnetic wave of the frequency to be shielded is single, a resonance-type frequency-selective electromagnetic wave blocking sheet having a resonance frequency equal to or as close as possible to the frequency to be shielded is used.

As a result, a single-frequency-selective electromagnetic wave shielding material having an improved electromagnetic wave shielding ability at the frequency to be shielded can be obtained.

The electric length of the electromagnetic wave means the wavelength of the electromagnetic wave traveling inside the spacer material.

The relative permittivity ε [-] of the spacer material used,
The thickness L [m] and the frequency f _s [GHz] of the electromagnetic wave to be shielded must satisfy the relationship represented by the following equation.

[0041]

(Equation 1)

For example, the lowest frequency of an electromagnetic wave to be shielded is 2 GHz, and PET is used as a spacer material.
When a film (ε = 4) is used, the thickness needs to be 500 μm or more according to the above equation. When 5 mm thick glass (ε = 7) is used as the spacer material, the minimum frequency of the electromagnetic wave to be shielded is 152
MHz.

In particular, as one mode of the frequency selective electromagnetic wave shielding material of the present invention, which is preferably used for securing communication cells for PHS and medium-speed wireless LAN, a plurality of resonance type frequency selective electromagnetic wave shielding sheet members are used for window glass. In the electromagnetic wave shielding material superimposed via the, the resonance frequency of the resonance type frequency selective electromagnetic wave shielding sheet on the indoor surface of the window glass is the resonance type frequency selective electromagnetic wave shielding sheet on the outdoor surface of the window glass. One that is 1.29 times or more higher than the resonance frequency is given.

In the electromagnetic wave shielding material of the present invention, two or more resonance-type frequency-selective electromagnetic wave shielding sheet bodies are stacked via a spacer material, but these are usually fixed in a stacked state.

The fixing method is well known to those skilled in the art. For example, an adhesive made of an insulating resin may be used, or an insulating base material or a spacer material may be melted and joined.

[0046]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Preparation Example 1 Formation of Conductive Pattern Nippon Paint's positive type liquid resist "OPTO ER P-60" was formed on an aluminum-deposited PET film (deposited film thickness: 500 °, PET thickness: 38 μm or 100 μm) manufactured by Oike Kogyo.
“0” was applied to a dry film thickness of 0.5 μm, and dried in a hot-air oven.

A mask is placed on the resist film, and the
/ Cm ² . The exposed resist was developed with 1% sodium hydroxide solution, and the exposed portions of the aluminum deposition film were etched. FIG. 3 having the dimensions shown in Table 1.
The conductive pattern Nos. Of the shapes and arrangements shown in FIGS. 1 to 9 were obtained respectively.

[0049]

[Table 1] Pattern Shape Dimension (mm) PET thickness No. Arrangement abcefgw (μm) 1 Fig. 3 37 0.3 2.5 100 2 Fig. 3 26 0.3 2.5 100 3 Fig. 4 8.5 0.5 0.3 38 4 Fig. 4 7.3 0.5 0.3 38 5 Fig. 4 10.1 0.5 0.3 38 6 Fig. 5 42 0.2 3.0 38 7 Fig. 5 20 1.1 3.0 38 8 Fig. 6 18 15 15 0.5 38 9 Fig. 6 12 9 9 0.5 38

Preparation Example 2 Resonant frequency-selective electromagnetic wave shielding sheet N shown in Table 2
o. 1-9 were prepared. The above-mentioned sheet body No. The conductive patterns Nos. 1, 2, 6 and 7 in Preparation Example 1 Table 1 1,
2, 6 and 7 were used as is.

The sheet body No. No. 3 is the conductive pattern No. of Preparation Example 1 Table 1. As shown in FIG. 7, two sheets of No. 3 were obtained by laminating them so that the conductive patterns were arranged alternately in a grid pattern so that the conductive patterns partially overlapped when viewed from a direction perpendicular to the plane. Planar N
o. 4 and 5 were similarly prepared. In FIG. 7, the solid line indicates the upper conductive pattern, and the broken line indicates the lower conductive pattern with the PET film interposed therebetween.

The sheet body No. 8 is the conductive pattern No. of Preparation Example 1 Table 1. As shown in FIG. 8, two sheets of No. 8 were obtained by laminating them so that the conductive patterns were arranged alternately in a grid pattern so that the conductive patterns partially overlapped when viewed from a direction perpendicular to the plane. Planar N
o. 9 was similarly prepared. 8, the solid line indicates the upper conductive pattern, and the broken line indicates the lower conductive pattern with the PET film interposed therebetween.

[0053]

[Table 2] Planar object Shape Pattern Lamination No. Arrangement No. Structure 1 Fig. 3 1 Al / PET 2 Fig. 3 2 Al / PET 3 Fig. 7 3 Al / PET / Al / PET 4 Fig. 7 4 Al / PET / Al / PET 5 Fig. 7 5 Al / PET / Al / PET 6 Fig. 5 6 Al / PET 7 Fig. 57 7 Al / PET 8 Fig. 8 8 Al / PET / Al / PET 9 Fig. 8 9 Al / PET / Al / PET

A double ridged guide antenna “HP-11966E” manufactured by EMCO is opposed at a distance of 1.5 m, and the obtained resonance-type frequency-selective electromagnetic wave shielding sheet is closely attached to the opening of the receiving antenna. I let it. In this state, S ₂₁ was measured using a network analyzer “HP-8510B” manufactured by Hewlett-Packard Company.

[0055] From the dB value of the S _21, minus the dB value of S ₂₁ measured without placing the resonant frequency selective electromagnetic wave blocking planar element to the opening surface of the receiving antenna. Obtained dB
The value was defined as the shielding ability of the resonance type frequency selective electromagnetic wave shielding sheet. Table 3 shows the measurement results. Table 3 also shows the shielding performance at typical frequencies used as communication waves.

Note that this shielding ability substantially coincides with the shielding ability obtained by a method based on MIL STD-285 using an electromagnetic wave shielding material as a wall material.

[0057]

[Table 3] Planar body Resonant point Shielding ability Shielding ability at communication frequency (GHz) No. Frequency (Hz) (dB) 1.5 1.9 2.45 5.7 1 1.4 28 (23) (9) 2 2.3 28 (8) (21) 3 1.9 23 (23) 4 2.45 24 (24) 5 1.5 22 (22) 6 3.0 25 (10) 7 7.0 22 (6) 8 1.9 21 (21) 9 2.45 21 (21)

Example 1 A window glass having a thickness of 5 mm was prepared as a spacer material. Preparation Example 2 Resonant frequency-selective electromagnetic wave shielding sheet No. 3 shown in Table 3 on one surface of this window glass using a spray paste manufactured by 3M. 1 was pasted. Then, on the other side of the window glass, the sheet-shaped body No. of Preparation Example 2 Table 3 was applied. 2 was attached to obtain a frequency-selective electromagnetic shielding material.

In the same manner as in Preparation Example 2, the shielding ability of the obtained frequency-selective electromagnetic wave shielding material was measured. Table 5 shows the measurement results. Table 5 also shows the shielding performance at typical frequencies used as communication waves.

Examples 2 to 8 and Comparative Examples 1 to 4 The frequency-selective electromagnetic wave shielding material was the same as in Example 1 except that the resonance type frequency-selective electromagnetic wave shielding sheet and the spacer shown in Table 4 were used. And the shielding ability was measured. Table 5 shows the results. Table 5 also shows the shielding performance at typical frequencies used as communication waves.

[0061]

[Table 4] Example Laminated structure No. Plane body No./spacer material [thickness] / planar body No. spacer material thickness / electrical length 1 1 / glass [5 mm] / 2 1 / 23 23 / glass [5 mm] / 4 1/13 2 / glass [5 mm] / 2 1/124 3 / gypsum board [9.5 mm] / 4 1/205 3 / PET [0.5 mm] / 4 1/158 6 3 / glass [5 mm] / 5 1/157 76 / PET [0.4 mm] / 7 1/153 88 / glass [5 mm] / 9 1/15 Comparison 13 / PET [0 .4 mm] / 4 1/197 Comparison 2 2 / Glass [5 mm]-Comparison 33 / Glass [5 mm]-Comparison 45 / Glass [5 mm]-

[0062]

[Table 5] Example Resonance point Shielding performance Shielding performance at communication frequency (GHz) No. Frequency (Hz) (dB) 1.5 1.9 2.45 5.7 1 1.4 28 (23) (10) (21) (3) 2.3 28 2 1.9 23 (2) (24) (24) (2) 2.45 24 3 2.3 (1) (25) (1) (1) 4 1.9 23 (2) (24) (24) (2) 2.45 24 5 1.9 23 ( 2) (23) (23) (2) 2.45 24 6 1.5 22 (27) (27) (2) (2) 1.9 23 7 3.0 25 (1) (1) (25) (24) 7.0 22 8 1.9 21 (21) (21) (1) (1) 2.45 21 Comparison 1 (2) (19) (12) (2) Comparison 2 (1) (21) (1) (1) Comparison 3 (2) (23) (2) (2) Comparison 4 (22) (2) (2) (2)

[0063]

According to the present invention, there is provided a resonance type electromagnetic wave shielding material which can perform electromagnetic wave shielding work without the need for grounding and can simultaneously block a plurality of electromagnetic waves having different frequencies. In particular, PHS (1.9 GHz) currently used as a private wireless data communication system and medium-speed wireless LAN
(2.45 GHz) can be shielded in a frequency-selective manner. In addition, this makes it possible to perform public line calls using portable wireless telephones (0.8 GHz and 1.5 GHz) at the same location while eliminating communication disturbance due to unnecessary external electromagnetic waves.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a resonance-type frequency-selective electromagnetic wave shielding sheet having a capacitance and an inductor formed thereon.

FIG. 2 is a perspective view showing an example of approach between conductive patterns.

FIG. 3 is a top view illustrating an example of an arrangement of conductive patterns.

FIG. 4 is a top view showing an example of an arrangement of conductive patterns.

FIG. 5 is a top view illustrating an example of an arrangement of conductive patterns.

FIG. 6 is a top view illustrating an example of an arrangement of conductive patterns.

FIG. 7 is a top view illustrating an example of an arrangement of conductive patterns.

FIG. 8 is a top view illustrating an example of an arrangement of conductive patterns.

[Explanation of symbols]

101, 111: an insulating base material; 102, 102 ', 112, 112': a unit of a conductive pattern; 103, 113: a portion where conductivity is interrupted.

Claims (10)

[Claims] 1. An electromagnetic wave shielding material comprising a plurality of resonance type frequency-selective electromagnetic wave shielding sheet members superposed via a spacer material, wherein the thickness of the spacer material is equal to the electrical length of the electromagnetic wave of the frequency to be shielded. An electromagnetic wave shielding material that is 1/160 or more. 2. The two resonance type frequency-selective electromagnetic wave shielding sheet members having the same resonance frequency among the plurality of resonance type frequency selective electromagnetic wave shielding member sheets have a higher resonance frequency. The electromagnetic wave shielding material according to claim 1, wherein a difference from the lower resonance frequency is 1/5 or more of the higher resonance frequency. 3. An electromagnetic wave shielding material comprising a plurality of resonance-type frequency-selective electromagnetic wave-blocking planar bodies stacked on each other with a spacer material interposed therebetween, wherein the thickness of the spacer material is such that the electrical length of the electromagnetic wave having the lowest frequency to be shielded. The electromagnetic shielding material is 1/160 or more of the above. 4. The electromagnetic wave shielding material according to claim 1, wherein the resonance type frequency-selective electromagnetic wave shielding sheet has a plurality of capacitors and inductors regularly arranged. 5. The resonance-type frequency-selective electromagnetic-wave-blocking planar body has an insulating substrate and a pattern of a plurality of conductive thin films regularly arranged on one surface thereof. 5. The pattern according to claim 4, wherein a line length of one unit of the pattern is shorter than a wavelength of the electromagnetic wave having the resonance frequency and is insulated from each other.
The described electromagnetic wave shielding material. 6. The resonance-type frequency-selective electromagnetic-wave-blocking planar body has an insulating base material and a pattern of a plurality of conductive thin films regularly arranged on both front and back surfaces thereof. 5. The pattern according to claim 4, wherein a line length of one unit of the pattern is shorter than a wavelength of the electromagnetic wave having the resonance frequency and is insulated from each other.
The described electromagnetic wave shielding material. 7. The electromagnetic shielding material according to claim 5, wherein the insulating base is an organic resin film. 8. The organic resin film having a thickness of 25 to 1
The electromagnetic wave shielding material according to claim 7, which has a thickness of 00 µm. 9. The electromagnetic wave shielding material according to claim 5, wherein when the formed electromagnetic wave shielding material is viewed from a direction perpendicular to its plane, the pattern made of the conductive thin film forms a grid at equal intervals. 10. A method for blocking electromagnetic waves, comprising the step of providing the electromagnetic wave shielding material according to claim 1 on a wall surface or a window surface of a building.