JP2001119192A - Radio wave anechoic box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install a grounded antenna or an antenna having a reflective surface in the inside, without having to provide conductors which form a ground surface or a reflective surface in the inside. SOLUTION: An anechoic box 1 comprises a frame composed of a door and a frame body 2b, a connector 4 is provided on the ceiling topside of the frame 2b for feeing and taking powers to and from an antenna 3 disposed in the frame 2, the frame 2b has a metal plate 6 forming a major portion of the frame 2 and a radio wave absorber 7 mounted on the inner wall of the metal plate 6, a radio wave absorber 7 is mounted on the inner wall of the metal plate 6 at a part of the frame 2b, except its ceiling, and the metal plate 6 on the ceiling of the frame 2b serves as a ground surface, when the antenna 3 is used as a grounded antenna and serves as a reflective surface when it is used as an antenna having a reflective surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Anechoic anechoic chambers are used for measuring antenna characteristics of mobile radio terminals and the like, and measuring the effects of electromagnetic radiation on electronic devices and small animals.

A conventional radio anechoic box is disclosed in, for example,
As shown in Japanese Patent No. 5596, a structure is adopted in which a radio wave absorber is disposed over the entire inner wall of a metal housing. Also,
In a conventional radio anechoic box, a connector to which an antenna is connected is provided inside so that a transmitting or receiving antenna can be installed inside.

[0004]

In the conventional radio anechoic box as described above, when a grounded antenna is installed inside, a ground plane (equipotential plane) is connected to a tip of a connector provided inside. It is necessary to connect the grounded antenna to the connector with the conductor provided. Also, in the conventional radio anechoic box, when installing an antenna with a reflective surface inside, connect the antenna to the connector with the conductor that becomes the reflective surface at the end of the connector provided inside. I needed to. For these reasons, the conventional radio anechoic box has a problem that the space inside the radio anechoic box may not be used effectively.

The present invention has been made in view of such a problem, and an object thereof is to provide a grounded antenna or an antenna having a reflection surface inside without providing a conductor serving as a ground surface or a reflection surface inside. It is an object of the present invention to provide a radio anechoic box capable of performing such operations.

[0006]

The radio anechoic box of the present invention comprises:
A housing having a conductor part constituting a main part and a radio wave absorber for suppressing reflection of radio waves on the inner wall,
At least a part of the conductor portion serves as a ground surface of a grounded antenna installed in the housing or a reflecting surface of an antenna having a reflecting surface.

In the radio anechoic box of the present invention, at least a part of the conductor portion of the housing becomes the ground surface of the grounded antenna or the reflecting surface of the antenna having the reflecting surface. There is no need to provide a conductor that becomes a surface or a reflective surface.

In the radio anechoic box of the present invention, the radio wave absorber is attached to the inner surface of the conductor except for the ground surface of the grounded antenna or the portion that becomes the reflection surface of the antenna having the reflection surface. You may.

Further, the radio anechoic box of the present invention may further include a connector provided on an outer surface of the housing and for inputting and outputting power to and from an antenna installed in the housing. . In this case, the connector may include a conductor portion that is electrically connected to a portion of the conductor portion that becomes a ground surface of the grounded antenna or a reflection surface of the antenna having the reflection surface. Further, the connector may have a connection portion to which an antenna installed in the housing is detachably connected. Further, the connector has an outer conductor portion as an outer conductor portion and an inner conductor portion as an inner conductor portion, the connection portion includes a female screw portion provided in the inner conductor portion, and the antenna is screwed into the female screw portion. It may have an external thread portion that fits.

Further, the radio anechoic box of the present invention may further include a protection member provided in the housing and made of a radio wave transmitting body for protecting the antenna installed in the housing.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing the appearance of a radio anechoic box according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the radio anechoic box shown in FIG. As shown in these drawings, a radio anechoic box 1 according to the present embodiment includes a housing 2. The front part of the housing 2 is a door 2a. Hereinafter, a portion of the housing 2 excluding the door 2a is referred to as a housing main body 2b. Part of the door 2a is constituted by a visible light transmitting radio wave absorber 10 that transmits visible light.

The size of the housing body 2b is, for example, 30
0 mm, width 225 mm, and depth 225 mm. The size of the door 2a is, for example, 300 mm in height and 22 in width.
5 mm and 30 mm in depth. In the door 2a, the position where the visible light transmitting radio wave absorber 10 is disposed is, for example, within a rectangular range of 240 mm in height and 165 mm in width, excluding the peripheral portion.

One end of the door 2a in the left-right direction is rotatably attached to the housing body 2b by, for example, a hinge, so that the door 2a can be opened and closed. Door 2
a, the other end in the left-right direction of the door 2a is fixed to the housing body 2b by, for example, a buckle,
The door 2a comes into close contact with the housing body 2b.

A connector 4 for inputting and outputting power to and from an antenna 3 disposed in the housing 2 as shown in FIG. 2 is provided on the upper surface (outer surface) of the ceiling portion of the housing body 2b. Is provided. Further, for example, four feet 5 are provided on the lower surface of the bottom of the housing body 2b.

As shown in FIG. 2, the housing main body 2b is provided with a metal plate 6 as a conductor part constituting a main part of the housing 2.
And a radio wave absorber 7 attached to the inner wall of the metal plate 6.
And In the present embodiment, in order to use the metal plate 6 in the ceiling portion of the housing body 2b as a ground surface (equipotential surface) of a grounded antenna or a reflecting surface of an antenna having a reflecting surface, the radio wave absorber 7 is It is attached to the inner wall of the metal plate 6 at a portion other than the ceiling portion of the housing body 2b.

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.

As the visible light transmitting radio wave absorber 10, for example, as shown 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.

In the example shown in FIG. 2, the housing body 2b
The radio wave absorber 7 is not provided on the entire ceiling portion of the housing body 2b in order to use the metal plate 6 in the entire ceiling portion as the ground surface of the grounded antenna or the reflection surface of the antenna having the reflection surface. However, in the case where only a part of the metal plate 6 around the antenna 3 is used as the ground surface of the grounded antenna or the reflecting surface of the antenna having the reflecting surface in the ceiling portion of the housing body 2b, FIG. As described above, the radio wave absorber 7 may not be provided on the inner wall of only a part of the metal plate 6 around the antenna 3, and the radio wave absorber 7 may be provided on the inner wall of the remaining metal plate 6.

FIG. 4 is a sectional view showing an example of the configuration of the connector 4 in FIG. Connector 4 in this example
Has an outer conductor portion 41 which is an outer conductor portion, an inner conductor portion 42 which is an inner conductor portion, and a dielectric portion 43 made of a dielectric which is disposed therebetween and insulates them. I have. At one end of the connector 4, a flange portion 41 a is formed on the outer conductor portion 41. This flange 41
a is a screw 45 at, for example, four locations around the periphery thereof.
Thereby, it is fixed to the metal plate 6 on the ceiling portion of the housing body 2b. At one end of the connector 4, the outer conductor 41 of the connector 4 is electrically connected to the metal plate 6, and the inner conductor 42 is insulated from the metal plate 6 by the dielectric portion 43. 6. Also,
The antenna 3 is connected to the inner conductor 42 at one end of the connector 4.

In the example shown in FIG. 4, at one end of the connector 4, a female screw portion is provided on the inner conductor portion 42, and a male screw portion 33 screwed to the female screw portion is provided on the antenna 3. Here, the female screw portion provided in the inner conductor portion 42 corresponds to a connection portion in the present invention to which the antenna 3 installed in the housing 2 is detachably connected. According to this configuration, the antenna 3 can be attached to and detached from the connector 4, so that the antenna 3 connected to the connector 4 can be easily changed, and the antenna 3 is installed in the radio anechoic box 1 only when necessary. It becomes possible to do.

The other end of the connector 4 is provided with a connection portion 44 to which a cable (not shown) for inputting and outputting power to and from the antenna 3 is detachably connected. In this connection part 44, the external conductor part 41 is provided with a male screw part 41b. Although not shown, at the end of the cable connected to the connector 4, there is provided a connector having a female screw portion to be screwed into the male screw portion 41b, and the female screw portion and the male screw portion 41b are screwed into a connector of the cable. Are connected to the connection section 44.

FIG. 5 is a sectional view showing another example of the configuration of the connector 4 in FIG. Connector 4 in this example
Has an outer conductor portion 51 which is an outer conductor portion, an inner conductor portion 52 which is an inner conductor portion, and a dielectric portion 53 made of a dielectric which is disposed therebetween and insulates them. I have. At one end of the connector 4, a flange portion 51 a is formed on the outer conductor portion 51. This flange portion 51
a is a screw 57 at, for example, four locations on the periphery thereof.
Thereby, it is fixed to the metal plate 6 on the ceiling portion of the housing body 2b. At one end of the connector 4, the outer conductor portion 51 of the connector 4 is electrically connected to the metal plate 6, and the inner conductor portion 52 is insulated from the metal plate 6 by the dielectric portion 53. 6.

The other end of the connector 4 is provided with a connection portion 54 to which a cable (not shown) for inputting and outputting power to and from the antenna 3 is detachably connected. In this connection portion 54, the outer conductor portion 51 is provided with a male screw portion 51b. Although not shown, at the end of the cable connected to the connector 4, a connector having a female screw portion to be screwed with the male screw portion 51b is provided, and by screwing the female screw portion and the male screw portion 51b, the connector of the cable is formed. Are connected to the connection unit 54.

In the example shown in FIG. 5, one end of the connector 4 is provided with a connection portion 55 which is disposed inside the housing 2b and to which the antenna 3 is detachably connected. The connecting portion 55 has an inner conductor portion 52 and one end of the dielectric portion 53, and an outer conductor portion 56 disposed outside the one end of the dielectric portion 53. A male screw portion 56 a is provided on the outer peripheral portion of the outer conductor portion 56.

On the other hand, an end of the antenna 3 on the connector 4 side is connected to the connecting portion 55 so as to be detachable from the connecting portion 55.
4 are provided. The connecting portion 34 includes an outer conductor portion 35 that is an outer conductor portion, an inner conductor portion 36 that is an inner conductor portion, and a dielectric portion 37 that is disposed therebetween and is made of a dielectric that insulates both. have. Inner conductor 36
Is provided with a female screw portion to which the male screw portion 33 of the antenna 3 is screwed, and the female screw portion and the male screw portion 33 are screwed to connect the antenna 3 to the inner conductor portion 36. The outer conductor portion 35 is formed in a substantially cylindrical shape or a regular hexagonal shape, and a female screw portion 35a screwed to the male screw portion 56a is provided on an inner peripheral portion thereof. When the female screw portion 35a and the male screw portion 56a are screwed together, the connection portion 34 is connected to the connection portion 55 of the connector 4 and the outer conductor portion 35 of the connection portion 34 is connected to the outer conductor portion 56 of the connector 4. It is designed to be electrically connected. The connection between the connection portion 34 and the connection portion 55 also electrically connects the inner conductor portion 36 of the connection portion 34 and the inner conductor portion 52 of the connector 4.

According to the configuration shown in FIG. 5, the antenna 3 can be attached to and detached from the connector 4, and the antenna 3 connected to the connector 4 can be easily changed. It becomes possible to install the antenna 3 in 1.

The antenna 3 connected to the connector 4 is, for example, a grounded antenna or an antenna having a reflecting surface. Examples of the ground type antenna include a capacitive top loading antenna, a λ (λ is the wavelength of a radio wave) / 4 resonance monopole antenna, a λ / 8 non-resonance monopole antenna, and the like.
Further, as an antenna having a reflecting surface, there are a helical antenna, a discone antenna, a corner reflector antenna, a parabolic antenna, and the like.

FIG. 6 is a perspective view showing a capacitive top loading antenna 30 as an example of the antenna 3.
This capacitive top loading antenna 30 has a λ / 8
It has an antenna element 32 equivalent to a non-resonant monopole antenna, and a capacitive loading 31 provided at one end of the antenna element 32. A male screw 33 is provided at the other end of the antenna element 32.

The radio anechoic box 1 according to the present embodiment further includes a protection member provided in the housing 2 and made of a radio wave transmitting body for protecting the antenna 3 installed in the housing 2. May be.

FIG. 7 is a sectional view showing an example of the protection member, and FIG.
FIG. 3 is a perspective view illustrating an example of a protection member. The protection member 61 in this example has a columnar shape having a trapezoidal cross section whose upper side is longer than its bottom side. The upper surface of the protection member 61 is joined to the lower surface of the metal plate 6 at the ceiling of the housing body 2b. In FIG. 7, reference numeral 60 denotes a direction of insertion and removal of a test object, which is an object of a test performed using the radio anechoic box 1. The protection members 61 are arranged one by one in front of and behind the antenna 3 along the direction 60 for inserting and carrying out the specimen.

FIG. 9 is a perspective view showing another example of the protection member. The protection member 62 in this example has a trapezoid, which is a cross-sectional shape of the protection member 61 shown in FIGS.
It has a columnar shape obtained by rotating around the antenna 3.

The protection members 61 and 62 are formed of a radio wave transmitting body. As the radio wave transmitting body, for example, polystyrene foam is used, but in addition, a foamed organic polymer such as foamed polyethylene or an organic polymer such as Teflon which can be regarded as a radio wave transmitting body may be used.

Next, referring to FIG. 10 to FIG. 14, when an antenna having a reflecting surface is used as the antenna 3, depending on the type of the antenna, the reflecting surface, that is, the metal on the ceiling portion of the housing body 2b. An example in which the inner surface of the plate 6 is not a flat surface will be described.

FIG. 10 is a perspective view showing a corner reflector antenna 110 as an example of the antenna 3. The corner reflector antenna 110 has an excitation dipole antenna 111 and a corner reflector 112 forming a reflection surface. Corner reflector 112
Is formed by joining two rectangular metal plates so as to form a predetermined angle. Excitation dipole antenna 111
Are arranged at the center of the corner reflector 112. In this corner reflector antenna 110, the radio wave radiated from the excitation dipole antenna 111 directly travels in the radiation direction 113, and the radio wave radiated from the excitation dipole antenna 111 is reflected by the corner reflector 112 and radiated in the radiation direction 113. And a reflected wave traveling to Then, by combining these direct waves and reflected waves, radio waves with higher directivity are emitted in the emission direction 113.

When a corner reflector antenna 110 as shown in FIG. 10 is used as the antenna 3,
The metal plate 6 in the ceiling portion of the housing body 2b functions as the corner reflector 112.

FIG. 11 is a cross-sectional view showing an example of a configuration of a main part of the radio wave anechoic box 2 in which a corner reflector antenna is installed as the antenna 3, and FIG. 12 shows a state in which the corner reflector member in FIG. FIG. 13 is a perspective view schematically showing a state in which the corner reflector member in FIG. 11 is viewed from the excitation dipole antenna side. In this example, a corner reflector member 114 made of the metal plate 6 is installed on the ceiling of the radio anechoic box. The corner reflector member 114 includes a corner reflector portion 114a formed by joining two rectangular metal plates at a predetermined angle, similarly to the corner reflector 112 shown in FIG. A triangular connecting portion 114b disposed at both ends of a boundary between two rectangular metal plates forming the reflector portion 114a and connecting between ends of the two rectangular metal plates; And a flange 114c provided on the periphery of the portion 114a and the connecting portion 114b. The corner reflector member 114 is installed on the ceiling of the radio wave anechoic box by fixing the flange portion 114c to the upper end of the housing body 2b with a plurality of screws 115.

An antenna connector 116 is provided inside the radio wave anechoic box at the center of the corner reflector portion 114a.
Is connected to the excitation dipole antenna 111. Further, a cable connector 117 to which a power input / output cable is connected is provided outside the radio wave anechoic box at the center of the corner reflector portion 114a.
The cable connector 117 is connected to the antenna connector 116.

A plate-shaped radio wave absorber is provided on the surface of the connection portion 114b of the corner reflector member 114 inside the radio anechoic box. Thereby, the corner reflector member 114 functions similarly to the corner reflector 112 shown in FIG.

FIG. 14 is a sectional view showing an example of a configuration of a main part of the radio wave anechoic box 2 in which a parabolic antenna is installed as the antenna 3. The parabolic antenna in this example has a primary radiator 121 installed inside the radio wave anechoic box 2 and a parabolic reflector 122. Reflecting mirror 122
Is made of a metal plate 6, the periphery of which is formed of a plurality of screws 123.
By being fixed to the upper end of the housing main body 2b, it is installed on the ceiling of the radio anechoic box.

Further, in the example shown in FIG.
A connector 124 for connecting a primary radiator is provided inside the radio wave anechoic box on the side wall portion b. The primary radiator connection connector 124 is connected to the primary radiator 121 via a cable 125. A cable connection connector 126 to which a power input / output cable is connected is provided inside the radio wave anechoic box on the side wall of the housing body 2b. The cable connection connector 126 is connected to the primary radiator connection connector 124.

In the parabolic antenna shown in FIG.
The radio wave radiated from the secondary radiator 121 is reflected by the reflecting mirror 122 and radiated in the radiation direction 127.

As shown in FIGS. 10 to 14, when a corner reflector antenna or a parabolic antenna is used as the antenna 3, for example, the shape of the reflecting surface formed by the conductor portion of the housing 2 is not flat. Instead, the reflection surface is a set of curved surfaces and surfaces with a structure.

Next, the operation of the radio anechoic box 1 according to this embodiment will be described. The radio anechoic box 1 is used for radio wave tests such as measurement of antenna characteristics of a mobile radio terminal and the like, and measurement of the influence of an electromagnetic wave irradiation on electronic devices and small animals. Electronic equipment, small animals, and the like are placed in the radio anechoic box 1 according to the intended use of the radio anechoic box 1. The antenna 3 installed in the radio anechoic box 1 is used for transmitting or receiving a radio wave in the radio wave test.

In the radio anechoic box 1 according to the present embodiment, when a grounded antenna is used as the antenna 3, the metal plate 6 on the ceiling portion of the housing body 2 b serves as a ground surface, and the antenna 3 has a reflection surface. When an antenna having the antenna is used, the metal plate 6 on the ceiling portion of the housing body 2b becomes a reflection surface. Therefore, according to the present embodiment, without providing a conductor serving as a ground surface or a reflection surface inside,
It becomes possible to install a grounded antenna or an antenna having a reflecting surface inside. Therefore, according to the present embodiment, the space inside radio wave anechoic box 1 can be effectively used.

According to the present embodiment, the connector 4 for inputting and outputting power to and from the antenna 3 disposed in the housing 2 is provided on the outer surface of the housing 2. 3 can be easily input and output.

In the present embodiment, the connector 4
However, when the antenna 3 has a connection portion to be detachably connected, the antenna 3 can be installed only when necessary.

According to the present embodiment, the protection member 61 or the protection member 62 made of a radio wave transmitting member for protecting the antenna 3 disposed in the housing 2 is provided in the housing 2. For example, the antenna 3 can be protected when a test object is inserted into the radio anechoic box 1 or when the test object is carried out of the radio anechoic box 1.

In the radio anechoic box 1 according to the present embodiment, a part of the door 2a is constituted by the visible light transmitting radio wave absorber 10. Therefore, according to the radio anechoic box 1 according to the present embodiment, radio wave reflection on the inner wall of the housing 2 is prevented and radio waves from the outside are prevented from entering the inside of the housing 2. While retaining the function of the sound box 1, the inside can be observed from outside through the visible light transmitting radio wave absorber 10. Thereby, for example, the radio anechoic box 1
In the radio wave test inside, it becomes possible to observe the operation status of electronic devices, the behavior of small animals, and the like.

Further, according to the present embodiment, in the casing 2, the radio wave absorber constituting at least a part other than the portion constituted by the visible light transmitting radio wave absorber 10 is replaced with a thin plate-shaped radio wave absorber. 7, the space inside the radio wave anechoic box 1 can be effectively used.

Further, according to the present embodiment, since the feet 5 are provided on the bottom of the housing 2, even if there is a protruding portion such as the connector 4 on the top or bottom of the housing 2, it does not matter. A plurality of radio anechoic boxes 1 can be stacked without being crushed.

Next, with reference to FIGS. 15 to 17, an example of the result of measuring the power distribution of the radio wave inside the radio anechoic box 1 according to the present embodiment will be described. FIG.
FIG. 2 is a schematic perspective view of the radio anechoic box 1 for describing a method of measuring a power distribution inside the radio anechoic box 1. In this example, the antenna 3 is used for transmission, and the capacitive top loading antenna 30 is used as the antenna 3. Further, in this example, a receiving dipole antenna 70 is arranged inside the radio wave anechoic box 1, and the power value of the radio wave transmitted from the capacitive top loading antenna 30 is measured using the dipole antenna 70. .

The dipole antenna 70 is arranged below the capacitive top loading antenna 30 in the same direction as the capacitive top loading antenna 30. Here, the arrangement direction of the capacitive top loading antenna 30 and the dipole antenna 70, that is, the vertical direction, is defined as the Z direction, and the direction perpendicular to the Z direction and parallel to the front surface of the radio anechoic box 1, that is, the door 2a, is defined as the X direction. The direction perpendicular to the direction and the X direction is defined as the Y direction. Then, the position inside the radio wave anechoic box 1 is defined by the coordinates (x,
y, z). Further, the position of the tip of the capacitive top loading antenna 30 is defined as (x, y, z) = (0, 0,
0) [Unit is mm]. The length of the capacitive top loading antenna 30 is, for example, 25 mm.

In this power distribution measurement, x = 0, y = −7
A surface of 5 to 75 [mm] and z = 37 to 187 [mm] is defined as a power distribution measurement surface 71. In the power distribution measurement surface 71, measurement is performed at 25 mm intervals in the Y direction and the Z direction. I have.

FIG. 16 is a perspective view showing a jig used for the power distribution measurement. The jig 80 has a metal plate 81 having the same size as the door 2a except for the thickness. The metal plate 81 has a slit 82 at a position corresponding to the measurement position in the Z direction, the slit 82 having a size capable of inserting the dipole antenna 70.
Is provided. The jig 80 further has a plate-shaped radio wave absorber 83 attached to a portion other than the slit 82 on one surface of the metal plate 81. This radio wave absorber 8
3 has the same radio wave reflection performance and radio wave attenuation performance as the visible light transmitting radio wave absorber 10. Note that the jig 80
A plurality of types having different positions of the slits 82 corresponding to the respective measurement positions in the Z direction are prepared.

In the power distribution measurement, the jig 8 shown in FIG.
0 is mounted on the housing body 2b instead of the door 2a. At this time, the slit 82 is arranged in a direction orthogonal to the direction of the electric field of the radio wave transmitted from the capacitive top loading antenna 30. In the power distribution measurement, the dipole antenna 70 is inserted into the housing body 2b through the slit 82,
The measurement is performed a plurality of times while changing the position of the dipole antenna 70 in the Y direction.

FIG. 17 is a characteristic diagram showing an example of the distribution of the reception level as a result of the power distribution measurement by the above method. In this figure, reference numeral 91 indicates a reception level of -15.
Reference numeral 92 denotes an area where the reception level is from −20.0 to −15.0 dBm, and reference numeral 93 denotes an area where the reception level is from −25.0 to −20.0 dBm. , Reference numeral 94 indicates that the reception level is -30.0 to -2.
A range of 5.0 dBm is shown.
Reference numeral 96 indicates an area where the reception level is -40.0 to -35.0 dBm, and reference numeral 97 indicates an area where the reception level is -45.0 to -40.0 dB.
The area of Bm is shown.

FIG. 17 shows that the position near the capacitive top loading antenna 30 is (x, y, z) = (0,
(0, 37) At the position of [unit: mm], the power value is locally large, and the effect of using the capacitive top loading antenna 30 can be confirmed.

The present invention is not limited to the above embodiment, and various changes can be made. For example, in the embodiment, the antenna 3 is installed on the ceiling portion of the housing 2; however, the position where the antenna 3 is installed is not limited to the ceiling portion, but may be a side portion or a bottom portion.

[0059]

As described above, according to the radio anechoic box according to any one of the first to seventh aspects, at least a part of the conductor portion of the housing is connected to the ground surface or the reflection surface of the grounded antenna. Since the antenna serves as a reflection surface of the antenna, a grounded antenna or an antenna having a reflection surface can be installed inside without providing a conductor serving as a ground surface or a reflection surface inside.

According to the radio anechoic box according to any one of claims 3 to 6, a connector for inputting / outputting electric power to / from an antenna disposed in the housing is provided on the outer surface of the housing. Is provided, the effect of facilitating the input and output of power to and from the antenna is achieved.

According to the radio wave anechoic box of the fifth or sixth aspect, the connector has a connection portion to which the antenna is detachably connected, so that the antenna can be installed only when necessary. This has the effect.

Further, according to the radio anechoic box of the present invention, since a protection member made of a radio wave transmitting member for protecting an antenna arranged in the housing is provided in the housing, for example, The antenna can be protected when the antenna is inserted into the radio anechoic box or when the specimen is carried out of the radio anechoic box.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a radio anechoic box according to an embodiment of the present invention.

FIG. 2 is a sectional view of the radio anechoic box shown in FIG.

FIG. 3 is a cross-sectional view of a modification of the radio anechoic box shown in FIG.

FIG. 4 is a sectional view showing an example of the configuration of the connector in FIG.

FIG. 5 is a sectional view showing another example of the configuration of the connector in FIG. 1;

FIG. 6 is a perspective view showing a capacitive top loading antenna as an example of the antenna in FIG. 2;

FIG. 7 is a cross-sectional view showing an example of a protection member provided in the radio wave anechoic box shown in FIG.

8 is a perspective view of the protection member shown in FIG.

FIG. 9 is a perspective view showing another example of the protection member provided in the radio wave anechoic box shown in FIG.

FIG. 10 is a perspective view showing a corner reflector antenna as an example of the antenna.

FIG. 11 is a cross-sectional view showing an example of a configuration of a main part of a radio wave anechoic box in which a corner reflector antenna is installed.

FIG. 12 is a perspective view showing a state in which the corner reflector member in FIG. 11 is viewed from above.

13 is a perspective view schematically showing a state in which the corner reflector member in FIG. 11 is viewed from an excitation dipole antenna side.

FIG. 14 is a cross-sectional view showing an example of a configuration of a main part of a radio wave anechoic box in which a parabolic antenna is installed.

15 is a schematic perspective view of a radio anechoic box for describing a method of measuring a power distribution inside the radio anechoic box shown in FIG. 1;

FIG. 16 is a perspective view showing a jig used for power distribution measurement inside the radio wave anechoic box shown in FIG.

FIG. 17 is a characteristic diagram showing a result of power distribution measurement inside the radio wave anechoic box shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radio wave anechoic box, 2 ... case, 2a ... door, 2b ... case main body, 3 ... antenna, 4 ... connector, 6 ... metal plate, 7 ... radio wave absorber, 10 ... visible light transmission radio wave absorber.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Takizawa, In-house TDC Corporation, 1-13-1 Nihonbashi, Chuo-ku, Tokyo (72) Osamu Fujiwara Ogisho-cho, Showa-ku, Nagoya-shi, Aichi, Japan Nagoya Institute of Technology F term (reference) 5E321 AA42 AA45 BB01 BB44 BB53 GG05 GG07 GG12 GH01

Claims (7)

[Claims] 1. A housing having a conductor portion constituting a main portion and a radio wave absorber for suppressing reflection of radio waves on an inner wall, wherein at least a part of the conductor portion is installed in the housing. A radio anechoic box characterized by being a ground surface of a grounded antenna or a reflecting surface of an antenna having a reflecting surface. 2. The radio wave absorber is attached to an inner surface of a portion of the conductor except for a ground surface of a grounded antenna or a portion that becomes a reflection surface of an antenna having a reflection surface. The radio anechoic box according to claim 1. 3. The apparatus according to claim 1, further comprising a connector provided on an outer surface of said housing for inputting and outputting power to and from an antenna installed in said housing. Radio anechoic box described. 4. The connector according to claim 1, wherein the connector has a conductor portion electrically connected to a portion of the conductor portion that becomes a ground surface of a grounded antenna or a reflection surface of an antenna having a reflection surface. Item 3. An anechoic box according to item 3. 5. The radio anechoic box according to claim 3, wherein the connector has a connection portion to which an antenna installed in the housing is detachably connected. 6. The connector has an outer conductor portion that is an outer conductor portion and an inner conductor portion that is an inner conductor portion, and the connection portion includes a female screw portion provided on the inner conductor portion. 6. The radio anechoic box according to claim 5, wherein the antenna has a male screw part screwed into the female screw part. 7. The apparatus according to claim 1, further comprising a protection member provided in said housing and made of a radio wave transmitting body for protecting an antenna installed in said housing. Radio anechoic box described in.