JP2001119193A - Radio wave anechoic room - Google Patents

Abstract

PROBLEM TO BE SOLVED: To observe the interior from the outside, without affecting the radio wave characteristics in the interior. SOLUTION: A window 4 and a door 5 are provided at a wall 3 between a radio wave darkroom 1 and a measuring room 2, the window 4 is formed by mounting a unit window composed of a radio wave absorber which causes visible rays pass through and a frame on the structure of the radio wave darkroom 1, and a radio wave reflecting layer o the visible ray transmissive radio wave absorber is connected electrically to a metal part around this radio wave absorber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anechoic chamber provided with a radio wave absorber for suppressing radio wave reflection on an inner wall of a room.

[0002]

2. Description of the Related Art Conventionally, for the purpose of measuring the radiated noise intensity of a device that generates noise that causes electromagnetic interference to other devices, and performing a malfunction test by irradiating a strong electromagnetic field to an electronic device. , An anechoic chamber is used.

A conventional anechoic chamber shields the room from electromagnetic waves by covering the entire room with an electromagnetic wave shielding material such as a metal plate, and provides a radio wave absorber on a wall surface or a ceiling surface of the room. It prevents the reflection of radio waves from the ceiling and ceiling.

As described above, in a conventional anechoic chamber, since the entire room is covered with a metal plate or the like, the inside cannot be observed from outside. For this reason, in the conventional anechoic chamber, when observing the inside of the anechoic chamber for observing a sample device or the like, a video camera is installed in the anechoic chamber.

[0005]

However, in an anechoic chamber in which a video camera is installed as described above, there is a problem that the radio wave characteristics inside the anechoic chamber may be adversely affected depending on the arrangement of the video cameras. There is a point.

In the conventional anechoic chamber, there is another problem that the cost is increased by installing a video camera inside.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a radio wave anechoic chamber in which the inside can be observed from outside without affecting the radio wave characteristics inside.

[0008]

An anechoic chamber according to the present invention includes a structure constituting a room and a radio wave absorber for suppressing reflection of radio waves on the inner wall of the room, and at least a part of the structure is provided. , And a visible light transmitting radio wave absorber that transmits visible light.

In the anechoic chamber of the present invention, since at least a part of the structure is constituted by the visible light transmitting radio wave absorber, the inside can be observed from the outside through the visible light transmitting radio wave absorber. .

[0010] In the anechoic chamber of the present invention, the visible light transmitting radio wave absorber may include a radio wave reflecting layer for reflecting radio waves.

Further, in the anechoic chamber of the present invention, the structure has a metal part disposed around the visible light transmitting radio wave absorber, and the anechoic chamber further includes a radio wave reflecting layer of the visible light transmitting radio wave absorber. Electrical connection means for electrically connecting the metal part to the metal part. In this case, the electrical connection means may include a conductive member having flexibility.

In the anechoic chamber of the present invention,
It comprises a frame that holds the visible light transmitting radio wave absorber, a window unitized by the visible light transmitting radio wave absorber and the frame is configured, and the structure has a metal portion arranged around the window,
The window may include an electrical connection unit that electrically connects the radio wave reflection layer of the visible light transmitting radio wave absorber and the metal part. In this case, the frame is made of dielectric or metal,
The electrical connection means includes a metal plate fixed to the frame and electrically connected to the metal portion, and a flexible conductive member for electrically connecting the radio wave reflection layer and the metal plate. May be. The dielectric constituting the frame may be a fiber-reinforced plastic or an organic polymer. Further, the radio wave absorber may be provided in a portion of the frame that protrudes into the anechoic chamber.

In the anechoic chamber of the present invention, at least a part of the structure may be constituted by a plurality of combined visible light transmitting radio wave absorbers. In this case, the visible light transmitting radio wave absorber includes a radio wave reflecting layer that reflects radio waves, and in a plurality of combined visible light transmitting radio wave absorbers,
The radio wave reflecting layers of the two visible light transmitting radio wave absorbers to be coupled may be electrically connected to each other.

In the anechoic chamber of the present invention, the radio wave reflecting layer of the visible light transmitting radio wave absorber may be made of a metal wire grid or a metal plate having a plurality of holes formed therein.

In the anechoic chamber of the present invention, the visible light transmitting radio wave absorber includes an optically transparent dielectric layer, and the radio wave reflecting layer of the visible light transmitting radio wave absorber is placed on the surface of the dielectric layer. It may be made of a formed optically transparent conductive film. In this case, the conductive film is made of a metal oxide, a metal nitride,
It may be made of metal or a mixture thereof. Further, the conductive film may be made of tin oxide, tin oxide-doped indium oxide, zinc oxide, titanium nitride, or silver. Further, the dielectric layer may be made of glass or a transparent organic polymer.

In the anechoic chamber of the present invention, the radio wave absorber except for the visible light transmitting radio wave absorber may include a plate-shaped radio wave absorber.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan sectional view showing an example of the configuration of a test facility including an anechoic chamber according to an embodiment of the present invention. The test equipment shown in FIG. 1 includes an anechoic chamber 1 according to the present embodiment and a measurement chamber 2 adjacent thereto.
And The anechoic chamber 1 includes a structure constituting a wall, a ceiling, and a floor of the room, and a radio wave absorber 7 for suppressing reflection of radio waves on the inner wall of the room. The structure has a metal plate 6 for shielding electromagnetic waves that covers the entire room except for a window and a door, which will be described later. Radio wave absorber 7
Are affixed to the indoor surface of the metal plate 6 on the wall and ceiling. The measurement chamber 2 is covered with a metal plate for shielding electromagnetic waves. Wall 3 between anechoic chamber 1 and measurement room 2
Is provided with a window 4 and a door 5.

As the radio wave absorber 7, for example, a thin plate-shaped ferrite rubber radio wave absorber is used. This plate-shaped ferrite rubber radio wave absorber is, for example,
As indicated by reference numeral 574, the electromagnetic wave absorber is made of a material obtained by mixing ferrite and synthetic rubber. The plate-shaped ferrite rubber radio wave absorber used in the present embodiment has a thickness of, for example, 7 mm, and has an energy absorption rate of 99% or more with respect to radio waves of 1.5 GHz. As the radio wave absorber 7, for example, a λ / 4 type radio wave absorber as disclosed in JP-A-5-14813 may be used instead of the plate-shaped ferrite rubber radio wave absorber. Note that λ represents the wavelength of a radio wave. Furthermore, as the radio wave absorber 7, it is naturally possible to use a pyramid-shaped or wedge-shaped radio wave absorber used in a general radio wave anechoic chamber or the like.

FIG. 2 shows an anechoic chamber 1 and a measuring chamber 2 in FIG.
It is a front view which shows the wall 3 between them. This figure shows a state where the wall 3 is viewed from the anechoic chamber 1 side. As aforementioned,
The wall 3 is provided with a window 4 and a door 5. The door 5 is provided with a rectangular window 8. Both the window 4 and the window 8 have a visible light transmitting radio wave absorber 10 that transmits visible light.
The window 4 has a configuration in which two rectangular visible light-transmitting radio wave absorbers 10 are arranged on the left and right sides, and both are connected by a connecting portion 9.

As the visible light transmitting radio wave absorber 10, for example, as disclosed in JP-A-6-120689,
It has a structure in which a resistive layer with appropriate surface resistance, a dielectric layer, and a radio wave reflective layer are laminated, and the resistive layer and the dielectric layer are made of an optically transparent material, and the radio wave reflective layer transmits light. Or a material made of a material that transmits light can be used.

FIG. 3 is a sectional view showing an example of the configuration of the visible light transmitting radio wave absorber 10 in the present embodiment. In this example, the visible light transmitting radio wave absorber 10 includes at least a radio wave reflecting layer 11 for reflecting radio waves, a radio wave absorbing layer 12 for absorbing radio waves, and a radio wave absorbing layer 10 at a predetermined frequency. The radio wave reflection layer 11 and the radio wave absorption layer 12 are arranged at a predetermined interval so that they function as a λ / 4 type radio wave absorber.
And a dielectric separating the same.

The radio wave reflection layer 11 may be made of, for example, a metal wire grid or a punching metal which is a metal plate having a plurality of holes formed thereon, or may be formed on an optically transparent dielectric layer. It may be constituted by the formed optically transparent conductive resistance film.

When the radio wave reflection layer 11 is formed of a conductive resistive film, the conductive resistive film includes, for example, a thin film made of a metal oxide, a metal nitride, a metal, or a mixture thereof. Specific examples of such a thin film include a thin film made of tin oxide, tin oxide-doped indium oxide (ITO), zinc oxide, titanium nitride, silver, or the like. Also,
The optically transparent dielectric layer may be made of, for example, transparent glass or polyethylene terephthalate (P
ET), acrylic, ABS resin, polycarbonate, Teflon, and other organic polymers. As a method for forming an optically transparent conductive film on the surface of the optically transparent dielectric layer, there are ion plating, vapor deposition, sputtering and the like.

Further, the radio wave absorbing layer 12 may be composed of, for example, an optically transparent resistive film formed on a surface of an optically transparent dielectric layer. As a resistive film,
For example, there is a thin film made of a metal oxide, a metal nitride, a metal, or a mixture thereof. As such a thin film,
Specifically, there is a thin film made of tin oxide, tin oxide-doped indium oxide, zinc oxide, titanium nitride, silver, or the like. The optically transparent dielectric layer may be made of, for example, transparent glass, or may be made of an organic polymer such as polyethylene terephthalate, acrylic, ABS resin, polycarbonate, and Teflon. As a method of forming an optically transparent resistive film on the surface of the optically transparent dielectric layer, there are ion plating, vapor deposition, sputtering and the like.

Hereinafter, an example in which the radio wave reflecting layer 11 is formed of a conductive resistive film and the radio wave absorbing layer 12 is formed of a resistive film will be described in detail with reference to FIG.
In this example, the radio wave reflection layer 11 is a thin film of tin oxide having a surface resistance of 10Ω □ formed on the surface of a dielectric layer 22 made of transparent glass having a thickness of 6 mm. The radio wave absorption layer 12 is a thin film of tin oxide-doped indium oxide having a surface resistance of 500Ω □ ± 10% formed on a surface of a dielectric layer 24 made of a 125 μm-thick polyethylene terephthalate film. .

The dielectric layer 22 and the dielectric layer 24 are disposed so as to face each other, and the gap adjusting dielectric layer 2 is interposed therebetween.
3 are arranged. The spacing adjusting dielectric layer 23 is made of, for example, glass having a thickness of 10 mm, but may be made of a transparent gas, liquid, organic polymer, or the like.

On the surface of the radio wave reflection layer 11 opposite to the dielectric layer 22, a protective dielectric layer 21 for protecting the radio wave reflection layer 11 is mounted. Similarly, a protective dielectric layer 25 for protecting the radio wave absorbing layer 12 is mounted on a surface of the radio wave absorbing layer 12 opposite to the dielectric layer 24. Each of the protective dielectric layers 21 and 25 is made of, for example, glass having a thickness of 3 mm, but may be made of a transparent organic polymer or the like.

Incidentally, in the example shown in FIG.
1 and the dielectric layer 22, and the radio wave absorbing layer 12 and the dielectric layer 24, respectively.
Are arranged so as to face outward, but may be arranged so that the radio wave reflecting layer 11 and the radio wave absorbing layer 12 face inward. In this case, the protective dielectric layers 21 and 25 become unnecessary.

In FIG. 3, between two adjacent layers, two layers that cannot be physically bonded, for example, the radio wave reflection layer 11 or the radio wave absorption layer 12 are formed on the surface of an optically transparent dielectric layer. Except for these layers when formed as an optically transparent conductive film by ion plating, vapor deposition, sputtering, etc., an optically transparent adhesive such as an acrylic adhesive, for example, an acrylic adhesive The adhesive may be bonded using an optically transparent double-sided adhesive tape such as a polyethylene terephthalate film having an adhesive layer on both sides.

When the radio wave reflecting layer 11 is formed of a metal wire grid or a punched metal instead of a conductive resistive film, the dielectric layer 22 is unnecessary.

In the thus constructed visible light transmitting radio wave absorber 10, most of the radio waves (incident waves 13) incident on the visible light transmitting radio wave absorber 10 from the radio wave reflecting layer 11 side pass through the radio wave reflecting layer 11. The light is reflected to become a reflected wave 14. On the other hand, most of the radio wave (incident wave 15) incident on the visible light transmitting radio wave absorber 10 from the radio wave absorbing layer 12 side is absorbed by the radio wave absorbing layer 12, and the reflected wave 16 hardly occurs.

The visible light transmitting radio wave absorber 10 shown in FIG.
Has a visible light transmittance of 75% or more. Further, the visible light transmitting radio wave absorber 10 has an energy absorbing rate of 99% or more in the radio wave absorbing layer 12 and an energy shielding rate of 98% or more in the radio wave reflecting layer 11 with respect to 1.5 GHz radio waves. Have.

Incidentally, in the example shown in FIG.
1, the surface resistance of the radio wave absorbing layer 12 was set to 500 Ω ± 10%, but if the surface resistance of the radio wave reflecting layer 11 or the dielectric constant of each dielectric layer changed, the energy of 99% or more was changed. The range of the surface resistance of the radio wave absorbing layer 12 that can achieve the absorptance changes.

The visible light transmitting radio wave absorber 10 shown in FIG.
Are arranged such that when used as the windows 4 and 8 shown in FIGS. 1 and 2, the radio wave reflecting layer 11 faces the outside of the anechoic chamber 1 and the radio wave absorbing layer 12 faces the indoor side of the anechoic chamber 1. You.

In the present embodiment, the windows 4 and 8 are provided with a visible light transmitting radio wave absorber 10 and a frame disposed around the visible light transmitting radio wave absorber 10 and holding the visible light transmitting radio wave absorber 10. It is a unit window that is unitized by

Referring to FIGS. 4 to 7, four examples of the structure of the unit window and its mounting method will be described. 4 to 7, the layers other than the radio wave reflection layer 11 among the layers of the visible light transmitting radio wave absorber 10 are simplified.

FIG. 4 is a sectional view for explaining a first example of the structure of the unit window and its mounting method. In the first example, the unit window is arranged around the visible light transmitting radio wave absorber 10 and has a frame 31 for holding the visible light transmitting radio wave absorber 10. The frame 31 is a visible light transmitting radio wave absorber 1
0, a portion 31a facing the peripheral portion of the surface on the indoor side (right side in FIG. 4), a portion 31b facing the peripheral portion on the surface outside the visible light transmitting radio wave absorber 10 (left side in FIG. 4), A portion 31c is provided at a position facing the outer peripheral portion of the visible light transmitting radio wave absorber 10 and connects the portions 31a and 31b.

The material of the frame 31 may be a dielectric or a metal. The dielectric may be, for example, fiber-reinforced plastic (FRP) or an organic polymer such as acrylic, ABS resin, polyethylene terephthalate, polycarbonate, and Teflon. Here, as an example, the frame 31
Shall be made of fiber-reinforced plastic.

The visible light transmitting radio wave absorber 10 is sandwiched between the portions 31a and 31b of the frame 31 and is held by the frame 31. In addition, a space is formed between the outer peripheral portion of the visible light transmitting radio wave absorber 10 and the portion 31c of the frame 31, and this space is filled with a gasket 32 for fixing the visible light transmitting radio wave absorber 10. ing. A gasket 33 for fixing the visible light transmitting radio wave absorber 10 is filled between the portion 31 a of the frame 31 and the visible light transmitting radio wave absorber 10. Note that there is no gap between the frame 31 and the visible light transmitting radio wave absorber 10,
When the visible light transmitting radio wave absorber 10 is fixed in the frame 31, the gaskets 32 and 33 are unnecessary.

The unit window further includes a portion 31b of the frame 31.
Has a metal plate 34 arranged at a position facing the.
The metal plate 34 has a shape slightly larger than the portion 31 b of the frame 31. The metal plate 34 is fixed to the portion 31b by, for example, a plurality of screws 35.

Radio wave reflecting layer 1 of visible light transmitting radio wave absorber 10
One end of a conductive member 36 having flexibility is electrically connected to the periphery of the first member. One end of the conductive member 36 is connected to the peripheral edge of the radio wave reflection layer 11 by being sandwiched between the radio wave reflection layer 11 and a dielectric layer adjacent thereto, for example. In addition, one end of the conductive member 36 is
The unit window is connected to the peripheral portion of the radio wave reflecting layer 11 over the entire circumference of the visible light transmitting radio wave absorber 10 within a range hidden by the metal plate 34 when viewed from the outside of the room (left side in FIG. 4). Examples of the flexible conductive member 36 include a conductive mesh and a conductive tape.

The other portion of the conductive member 36 passes through the space between the outer peripheral portion of the visible light transmitting radio wave absorber 10 and the portion 31c of the frame 31, and further passes through the portion of the visible light transmitting radio wave absorber 10 and the frame 31. 31b, and is sandwiched between the portion 31b of the frame 31 and the metal plate 34. Thus, the radio wave reflecting layer 11 of the visible light transmitting radio wave absorber 10 and the metal plate 34
Are electrically connected via a conductive member 36.

In the portion for mounting the unit window configured as described above, an opening having a shape slightly smaller than the unit window is formed in the metal portion 60 having the electromagnetic wave shielding function in the wall 3 or the door 4. Metal part 60
Is a metal plate constituting the metal plate 6 or the door 4 on the wall 3, for example. The unit window is formed by welding or soldering the metal plate 34 to the metal portion 60, for example.
It is fixed to a metal part 60 arranged around the unit window (visible light transmitting radio wave absorber 10). This also gives
The metal plate 34 and the metal portion 60 are electrically connected, and the radio wave reflecting layer 11 of the visible light transmitting radio wave absorber 10
6 and the metal part 60 via the metal plate 34. The conductive member 36 and the metal plate 34 correspond to the electric connection means in the present invention.

When the frame 31 is made of metal,
The radio wave reflection layer 11 and the metal portion 60 may be electrically connected according to the above method, or the metal plate 34 is removed, the conductive member 36 is electrically connected to the frame 31, and the frame 31 is connected to the metal portion 60. , The electric wave reflection layer 11 and the metal portion 60 may be electrically connected. Also, frame 31
Is formed of metal, as shown in FIG.
It is preferable to install the radio wave absorber 37 in a portion of the device 1 that protrudes into the anechoic chamber.

FIG. 5 is a sectional view for explaining a second example of the structure of the unit window and its mounting method. The structure of the unit window in the second example is the same as in the first example.
In the second example, the opening formed in the metal part 60 in the portion where the unit window is attached is slightly larger than the unit window. In the second example, the conductive mesh 41 is sandwiched between the metal plate 34 and the metal portion 60, and the screws 42
Thus, the metal plate 34 is fixed to the metal part 60.

FIG. 6 is a sectional view for explaining a third example of the structure of the unit window and its mounting method. In the third example, in addition to the portions 31a, 31b, and 31c, the frame 31 includes a portion 31a from the boundary between the portions 31a and 31c.
It has a portion 31d formed so as to extend indoors (to the right in FIG. 6) in parallel with c. The metal plate 34
Is a portion 34a facing the portion 31b of the frame 31;
A portion 34b is formed so as to extend to the outdoor side (left side in FIG. 6) so as to form substantially the same surface as the first portion 31c and the portion 31d. Other structures of the unit window in the third example are the same as those in the first example.

In the third example, the metal portion 60 disposed around the unit window has portions facing the portions 31c and 31d of the frame 31 and the portion 34b of the metal plate 34. In the third example, the conductive mesh 43 is interposed between the portions 31c and 31d of the frame 31 and the portion 34b of the metal plate 34 and the metal portion 60 opposed thereto, and a plurality of screws are provided at the peripheral portion of the frame 31. The portions 31d of the frame 31 and the portion 34b of the metal plate 34 are
It is fixed to 0.

FIG. 7 is a cross-sectional view for explaining a fourth example of the structure of the unit window and its mounting method. In the fourth example, a frame 51 is provided instead of the frame 31. Frame 5
1 is a portion 51a facing a peripheral portion of a surface on the indoor side (the right side in FIG. 7) of the visible light transmitting radio wave absorber 10,
A portion 51b facing the peripheral portion of the surface on the outdoor side (left side in FIG. 7) of the visible light transmitting radio wave absorber 10 and a portion 51a, 51b disposed at a position facing the outer peripheral portion of the visible light transmitting radio wave absorber 10. And a portion 51c for connecting. The material of the frame 51 is the same as that of the frame 31 in the first example.

The visible light transmitting radio wave absorber 10 is sandwiched between the portions 51a and 51b of the frame 51 and is held by the frame 51. Further, a space is formed between the outer peripheral portion of the visible light transmitting radio wave absorber 10 and the portion 51c of the frame 51, and this space is filled with a gasket 52 for fixing the visible light transmitting radio wave absorber 10. ing. A gasket 53 for fixing the visible light transmitting radio wave absorber 10 is filled between the portion 51 b of the frame 51 and the visible light transmitting radio wave absorber 10. Note that there is no gap between the frame 51 and the visible light transmitting radio wave absorber 10,
When the visible light transmitting radio wave absorber 10 is fixed in the frame 51, the gaskets 52 and 53 are unnecessary.

The unit window further includes a portion 51a of the frame 51.
And a metal plate 54 disposed at a position opposed to.
The metal plate 54 has a shape slightly larger than the portion 51 a of the frame 51. The metal plate 54 is fixed to the portion 51a by, for example, a plurality of screws 55.

Radio wave reflecting layer 1 of visible light transmitting radio wave absorber 10
The electrically conductive member 36 electrically connected to the peripheral portion of the frame 1 includes the outer peripheral portion of the visible light transmitting radio wave absorber 10 and the portion 51 c of the frame 51.
And further passes between the visible light-transmitting radio wave absorber 10 and the portion 51a of the frame 51 to pass through the portion 51 of the frame 51.
a and the metal plate 54.

A plurality of finger contacts 56 are joined to the entire surface of the metal plate 54 on the indoor side (the right side in FIG. 7). The finger contact 56 is a leaf spring-shaped member made of metal and having an intermediate portion protruding.

In the fourth example, the opening formed in the metal portion 60 in the portion where the unit window is mounted is slightly smaller than the unit window. In the fourth example, the metal plate 54 is fixed to the metal portion 60 by screws 57 while the metal plate 54 and the metal portion 60 are electrically connected by finger contacts 56. Thus, the radio wave reflecting layer 11 of the visible light transmitting radio wave absorber 10 is electrically connected to the metal portion 60 via the conductive member 36, the metal plate 54, and the finger contacts 56. Conductive member 3
6, the metal plate 54 and the finger contacts 56 correspond to the electrical connection means in the present invention. Also, instead of the finger contacts 56, a conductive mesh corresponding to the size of the metal plate 54 is sandwiched between the metal plate 54 and the metal portion 60, so that the metal plate 54 and the metal portion 60 are formed.
May be electrically connected.

Next, referring to the cross-sectional view of FIG. 8, the visible light transmitting radio wave absorber 10 in a unit window having a structure in which a plurality of visible light transmitting radio wave absorbers 10 are coupled like the window 4 in FIG. An example of the structure of the connecting portion will be described. In this example, the unit window includes two visible light transmitting radio wave absorbers 1
It has a frame 71 for connecting 0s. The frame 71 has an H-shaped cross section and has two grooves. And
The ends of the visible light transmitting radio wave absorber 10 are inserted into the two grooves, respectively. Between the portion of the frame 71 on the indoor side (the right side in FIG. 8) and each visible light transmitting radio wave absorber 10,
Each is filled with a gasket 73 for fixing the visible light transmitting radio wave absorber 10. In the case where the visible light transmitting radio wave absorber 10 is fixed in the frame 71 without any gap between the frame 71 and the visible light transmitting radio wave absorber 10, the gasket 73 is unnecessary.

The material of the frame 71 may be a dielectric or a metal. The dielectric may be, for example, a fiber-reinforced plastic, or an organic polymer such as acrylic, ABS resin, polyethylene terephthalate, polycarbonate, or Teflon. Here, as an example, the frame 71 is made of fiber-reinforced plastic.

The unit window further has a metal plate 74 arranged at a position facing a portion of the frame 71 on the outside (left side in FIG. 8). The metal plate 74 is fixed to the frame 71 by a plurality of screws 75, for example.

One end of a flexible conductive member 76 is electrically connected to the periphery of the radio wave reflecting layer 11 of each visible light transmitting radio wave absorber 10. One end of the conductive member 76 is connected to the peripheral edge of the radio wave reflection layer 11 by being sandwiched between the radio wave reflection layer 11 and a dielectric layer adjacent thereto, for example. Examples of the flexible conductive member 76 include a conductive mesh and a conductive tape.

The other part of the conductive member 76 passes between the visible light transmitting radio wave absorber 10 and the frame 71 and is sandwiched between the frame 71 and the metal plate 74. In this manner, the radio wave reflecting layers 1 of the two visible light transmitting radio wave absorbers 10 to be combined are combined.
1 are electrically connected to each other via a conductive member 76 and a metal plate 74. This prevents the leakage or entry of the radio wave at the joint of the two visible light transmitting radio wave absorbers 10.

According to the unit window having such a structure, 2
It is possible to manufacture a large unit window in which a plurality of visible light transmitting radio wave absorbers 10 are connected while maintaining the radio wave shielding performance and mechanical strength of the connection portion of the two visible light transmitting radio wave absorbers 10.

Next, with reference to the sectional view of FIG. 9, an example of the structure of the connecting portion of the visible light transmitting radio wave absorber when two visible light transmitting radio wave absorbers are connected without using a frame will be described. . In this example, the visible light transmitting radio wave absorber 10
Has a configuration in which the protective dielectric layers 21 and 25 are removed from the configuration shown in FIG. The electric wave reflecting layers 11 of the two visible light transmitting electric wave absorbers 10 to be connected to each other are electrically connected by a conductive mesh 82 composed of conductive fibers that are coarse enough to have visible performance or thin enough to have visible performance. Connected. This prevents the leakage or entry of the radio wave at the joint of the two visible light transmitting radio wave absorbers 10.

In the example shown in FIG. 9, a holding dielectric plate 81 is arranged so as to face the radio wave reflection layer 11, and a holding dielectric plate 85 is arranged so as to face the radio wave absorption layer 12. . The holding dielectric plates 81 and 85 are arranged such that the positions of their ends are different from the positions where the two visible light transmitting radio wave absorbers 10 are joined. When connecting the plurality of holding dielectric plates 81 and 85, the holding dielectric plates 81 and 85 and the visible light transmitting radio wave absorber 10 are alternately arranged.

Each of the holding dielectric plates 81 and 85 is made of, for example, glass having a thickness of 3 mm, but may be made of an organic polymer or the like.

In FIG. 9, between two adjacent layers, two layers that cannot be physically bonded, for example, the radio wave reflection layer 11 or the radio wave absorption layer 12 are formed on the surface of an optically transparent dielectric layer. Except for these layers when formed as an optically transparent conductive film by ion plating, vapor deposition, sputtering, etc., an optically transparent adhesive such as an acrylic adhesive, for example, an acrylic adhesive The adhesive may be bonded using an optically transparent double-sided adhesive tape such as a polyethylene terephthalate film having an adhesive layer on both sides.

According to the structure shown in FIG. 9, the large visible light-transmitting radio wave absorbers 10 are combined without deteriorating the radio wave shielding performance and the visible performance of the connecting portion of the two visible light transmitting radio wave absorbers 10. Can be manufactured.

A visible light transmitting radio wave absorber formed by combining a plurality of visible light transmitting radio wave absorbers 10 with the structure shown in FIG. 9 is used for the unit window as in the above-described first to fourth examples. This makes it possible to manufacture a large unit window.

Next, the operation of the anechoic chamber 1 according to the present embodiment will be described. Anechoic chamber 1 according to the present embodiment
Is used for radio wave tests of mobile radio terminals, etc., and operation and tests of wireless LANs (local area networks).

In the anechoic chamber 1 according to the present embodiment, a part of the wall 3, which is a structure constituting the anechoic chamber 1, is constituted by the visible light transmitting radio wave absorber 10, and the windows 4 and 8 are formed. I have. Therefore, according to the anechoic chamber 1 according to the present embodiment, the function of the anechoic chamber 1 for preventing reflection of radio waves on the inner wall and preventing radio waves from the outside from entering the inside is maintained while maintaining the function of the anechoic chamber 1. The inside can be observed from the outside through the transmitted radio wave absorber 10.

According to the present embodiment, the anechoic chamber 1
It is not necessary to install a television camera or the like inside the anechoic chamber 1 to observe the inside of the anechoic chamber 1, so that it is possible to observe the inside from the outside without affecting the radio wave characteristics inside the anechoic chamber 1 The cost does not increase.

According to the present embodiment, the radio wave reflecting layer 11 of the visible light transmitting radio wave absorber 10 and the metal portion 60 around the visible light transmitting radio wave absorber 10 are connected via the conductive member 36 or the like. Since the connection is made electrically, the leakage or intrusion of the radio wave between the visible light transmitting radio wave absorber 10 and the surrounding portion can be prevented.

Further, according to the present embodiment, a unit window is constituted by the visible light transmitting radio wave absorber 10 and the frame, and this unit window is attached to the structure of the radio wave anechoic chamber 1. Construction is easy.

According to the present embodiment, when a plurality of visible light transmitting radio wave absorbers 10 are combined,
Since the radio wave reflection layers 11 of the two visible light transmitting radio wave absorbers 10 are electrically connected to each other, it is possible to prevent leakage or intrusion of radio waves at the joint of the visible light transmitting radio wave absorbers 10.

Further, according to the present embodiment, since the radio wave absorber except the visible light transmitting radio wave absorber 10 is the thin plate-shaped radio wave absorber 7, the space inside the radio wave anechoic chamber 1 is effectively used. It becomes possible to do. Further, it is possible to provide a decorative plate on the surface of the plate-shaped radio wave absorber 7. Therefore, the use of the plate-shaped radio wave absorber 7 is effective when the radio wave anechoic chamber 1 is used as a small base station of a mobile phone having a limited frequency, or used for testing or operating a wireless LAN. is there.

The present invention is not limited to the above embodiment, and various changes can be made. For example, in the embodiment, a part of the wall 3 is configured by the visible light transmitting radio wave absorber 10, but at least a part of the ceiling and the floor may be configured by the visible light transmitting radio wave absorber 10. Anechoic chamber 1
May be constituted entirely by the visible light transmitting radio wave absorber 10.

[0074]

As described above, claims 1 to 16 are provided.
According to the anechoic chamber described in any of the above, at least a part of the structure is composed of a visible light transmitting radio wave absorber, so it is possible to observe the inside from the outside without affecting the radio wave characteristics inside This has the effect of becoming

Further, claims 2 to 8, 10 to 15
According to the anechoic chamber described in any of the above, since the visible light transmitting radio wave absorber includes a radio wave reflecting layer that reflects radio waves, the effect that external radio waves can be prevented from entering the anechoic chamber can be obtained. Play.

According to the anechoic chamber of the third or fourth aspect, the radio wave reflecting layer of the visible light transmitting radio wave absorber is electrically connected to the metal portion disposed around the visible light transmitting radio wave absorber. Since the electrical connection means is provided, it is possible to prevent an electric wave from leaking or entering between the portion constituted by the visible light transmitting radio wave absorber and the metal portion.

According to the anechoic chamber according to any one of claims 5 to 8, since the window unitized by the visible light transmitting radio wave absorber and the frame is formed, the installation of the anechoic chamber is facilitated. This has the effect.

Further, according to the anechoic chamber of the tenth aspect, at least a part of the structure is constituted by a plurality of visible light transmitting radio wave absorbers coupled to each other, and the two visible light transmitting radio wave absorbers are coupled. Since the radio wave reflecting layers are electrically connected to each other, it is possible to prevent the radio wave from leaking or entering at the joint of the visible light transmitting radio wave absorber.

According to the anechoic chamber of the sixteenth aspect, since the radio wave absorber except the visible light transmitting radio wave absorber includes the plate-shaped radio wave absorber, the space inside the anechoic chamber can be effectively used. This has the effect that it can be used.

[Brief description of the drawings]

FIG. 1 is a plan sectional view showing an example of a configuration of a test facility including an anechoic chamber according to an embodiment of the present invention.

FIG. 2 is a front view showing a wall between an anechoic chamber and a measurement chamber in FIG.

FIG. 3 is a cross-sectional view illustrating an example of a configuration of a visible light transmitting radio wave absorber according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a first example of a structure of a unit window and a method of attaching the unit window in one embodiment of the present invention.

FIG. 5 is a cross-sectional view for explaining a second example of the structure of the unit window and the method of attaching the unit window in one embodiment of the present invention.

FIG. 6 is a cross-sectional view for explaining a third example of the structure of the unit window and the method of attaching the unit window in the embodiment of the present invention.

FIG. 7 is a cross-sectional view for explaining a fourth example of the structure of the unit window and the method of attaching the unit window in the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a structure of a coupling portion of a visible light transmitting radio wave absorber according to one embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a structure of a coupling portion of a visible light transmitting radio wave absorber according to one embodiment of the present invention.

[Explanation of symbols]

1 ... anechoic chamber, 3 ... wall, 4 ... window, 5 ... door, 6 ... metal plate,
7: radio wave absorber, 8: window, 10: visible light transmitting radio wave absorber, 11: radio wave reflection layer, 12: radio wave absorption layer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Takizawa inventor TDK Corporation, 1-13-1 Nihonbashi, Chuo-ku, Tokyo (72) Osamu Fujiwara Ogishocho, Showa-ku, Nagoya-shi, Aichi Prefecture Nagoya Institute of Technology F term (reference) 2F078 HA13 HA20 5E321 AA42 AA46 BB23 BB25 BB34 BB41 BB44 CC12 CC16 CC22 GG05 GG07 GG11 GH01

Claims (16)

[Claims] 1. A structure comprising a room, and a radio wave absorber for suppressing reflection of radio waves on the inner wall of the room, wherein at least a part of the structure is a visible light transmitting radio wave transmitting visible light. An anechoic chamber characterized by being constituted by an absorber. 2. The radio wave anechoic chamber according to claim 1, wherein the visible light transmitting radio wave absorber includes a radio wave reflection layer that reflects radio waves. 3. The structure has a metal portion disposed around the visible light-transmitting radio wave absorber. The anechoic chamber further includes the radio wave reflection layer of the visible light transmitting radio wave absorber and the metal member. 3. The anechoic chamber according to claim 2, further comprising an electrical connection means for electrically connecting the parts. 4. The anechoic chamber according to claim 3, wherein said electric connection means includes a conductive member having flexibility. 5. The apparatus further comprises a frame for holding the visible light transmitting radio wave absorber, wherein a window unitized by the visible light transmitting radio wave absorber and the frame is formed. It has a metal part arranged around, The window has electric connection means which electrically connects the radio wave reflection layer of the visible light transmitting radio wave absorber and the metal part. Item 2. An anechoic chamber according to item 2. 6. The frame is made of a dielectric material or a metal, and the electrical connection means is a metal plate fixed to the frame and electrically connected to the metal portion, the radio wave reflection layer and the metal. 6. The anechoic chamber according to claim 5, further comprising: a flexible conductive member that electrically connects the plate and the board. 7. The anechoic chamber according to claim 6, wherein the frame is made of a dielectric material, and the dielectric material constituting the frame is a fiber-reinforced plastic or an organic polymer. 8. The anechoic chamber according to claim 5, wherein a radio wave absorber is provided in a portion of the frame protruding into the anechoic chamber. 9. The anechoic chamber according to claim 1, wherein at least a part of the structure is constituted by a plurality of visible light transmitting radio wave absorbers coupled to each other. 10. The visible light transmitting radio wave absorber includes a radio wave reflecting layer that reflects a radio wave, and in the plurality of combined visible light transmitting radio wave absorbers,
The radio wave anechoic chamber according to claim 9, wherein the radio wave reflection layers of the two visible light transmitting radio wave absorbers to be coupled are electrically connected to each other. 11. The radio wave reflection layer of the visible light transmitting radio wave absorber comprises a metal wire grid or a metal plate having a plurality of holes formed therein. The anechoic chamber described. 12. The visible light transmitting radio wave absorber includes an optically transparent dielectric layer, and the radio wave reflecting layer of the visible light transmitting radio wave absorber is formed on a surface of the dielectric layer. 11. The anechoic chamber according to claim 2, wherein the anechoic chamber is made of an optically transparent conductive film. 13. The anechoic chamber according to claim 12, wherein said conductive film is made of a metal oxide, a metal nitride, a metal, or a mixture thereof. 14. The anechoic chamber according to claim 13, wherein said conductive film is made of tin oxide, tin oxide doped indium oxide, zinc oxide, titanium nitride or silver. 15. The anechoic chamber according to claim 12, wherein the dielectric layer is made of glass or a transparent organic polymer. 16. The anechoic chamber according to claim 1, wherein the radio wave absorber other than the visible light transmitting radio wave absorber includes a plate-shaped radio wave absorber.