JPH02303097A - Radio wave anechoic chamber - Google Patents

Abstract

PURPOSE:To prevent a reflected wave from arriving at a reception antenna by forming the walls of a radio wave anechoic chamber of a metal material, arranging many conical radio wave absorbers made of a radio wave absorption material inside at least one wall of a floor wall, four sidewalls and a ceiling wall, and providing random reflectors on the walls. CONSTITUTION:An electromagnetic wave oscillated from an oscillation source 18 is radiated radially in addition to a reception antenna 19, and arrives at radio wave absorbers 20. The wave is partly reflected on the surfaces of the absorbers 20, and residually transmitted therethrough. The waves which are transmitted through the absorbers 21 and arrived at random reflecting faces 23 of random reflectors 24 are not reflected perpendicularly toward a flat bottom 22 but mostly reflected in a state inclined toward the bottom 22. When the waves are inclined and reflected in this manner, the waves are not transmitted through a radio wave absorbing plate 22 disposed in the bottom but reflected here. The reflected wave is further reflected on the surfaces of the reflectors 23 to be gradually attenuated. Accordingly, the waves transmitted through the absorbers 20 are reflected on the wall 12, not returned to a radio wave anechoic chamber, but repeatedly reflected between the absorbers 20 and the absorbers 23 to be absorbed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a radio anechoic chamber, which is also called a radio anechoic chamber, radio semi-anechoic chamber, or radio wave no-reflection chamber, and particularly relates to a radio anechoic chamber, which is also called a radio wave anechoic chamber, a radio wave semi-anechoic chamber, or a radio wave no-reflection chamber. This invention relates to a radio anechoic chamber that can also perform measurements on radio waves.

(Prior art) Since various electronic devices such as computers generate electromagnetic noise, how about the radio waves generated by these devices? 11 may be set. Basically, performing this measurement outdoors is the best way to detect the propagation conditions of the generated radio waves. However, if such measurements are made outdoors, they will be affected by external radio waves, making it difficult to be accurate. Not only is it not possible to perform accurate measurements, but the measurement work is dependent on the weather, and reproducibility of measurements cannot be expected. Furthermore, when examining the characteristics of a newly developed antenna, it is necessary to determine the reception condition so as not to be influenced by external radio waves.

Therefore, a radio anechoic chamber has been developed in order to be able to perform the above-mentioned measurements while eliminating the influence of external radio waves. A semi-anechoic chamber assumes that the radio waves emitted from the radio wave source to the receiving antenna include reflected waves from the ground, and assuming outer space, the receiving antenna also receives reflected waves from the ground. In some cases, the term radio anechoic chamber is used in a narrow sense, only when the waves are prevented from entering the room, and in a broader sense, it also includes cases in which reflected waves from the ground are allowed to enter the room. There is something to be said.

In conventional radio anechoic chambers, a radio anechoic chamber with an internal storage space is formed using wall materials made of metal materials in order to shield external radio waves, and the radio waves provided in this storage space are Radio wave absorbers are attached to the inner surface of wall materials to prevent radio waves from being reflected. As a conventionally used radio wave absorber, a square pyramid-shaped radio wave absorber is usually used. This type of radio wave absorber is made by impregnating urethane foam with carbon powder, and is also called a resistive radio wave absorber.

(Problem to be solved by the invention) This type of radio wave absorber converts the electric energy of radio waves into thermal energy by the heating action of the resistor, and absorbs radio waves while avoiding reflections that go directly from the absorber to the receiver. It was designed to do this. The performance of this radio wave absorber is most dependent on the length of the pyramid, which must be set to one-third or more of the wavelength of the radio waves to be absorbed. In addition, as mentioned above, this type of radio wave absorber attenuates electromagnetic waves by converting them into thermal energy while transmitting them, but it is not completely attenuated, creating a radio anechoic chamber. The electromagnetic waves that reach the metal wall are further reflected there, and some of the electromagnetic waves may return to the inside of the radio anechoic chamber by passing through the radio wave absorber again.

The presence of such return radio waves makes it impossible to perform highly accurate measurements.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to prevent the radio waves that have passed through the bottom of the radio wave absorber from returning to the inside of the radio anechoic chamber.

(Means for Solving the Problems) In order to achieve the object described in 1, the present invention forms a storage space inside by a floor wall, side walls of the front, rear, left and right walls, and a ceiling wall, and a storage space is formed inside the storage space. In a radio anechoic chamber provided with a transmitting source that transmits radio waves and a receiving antenna that receives radio waves from the transmitting source, each of the walls is formed of a metal material, and the floor wall and the four A large number of cone-shaped radio wave absorbers made of radio wave absorbing material are arranged inside at least one of the two side walls and the ceiling wall,
At the bottom of each of the radio wave absorbers, there is a ゛P- along the wall.
A diffused reflection part is formed on the inner surface of the wall forming a river surface and on which the radio wave absorbers are arranged, forming a diffused reflection surface that tilts and reflects the radio waves that have passed through the flat surface toward the flat surface. It is a radio anechoic chamber.

(Function) On the inside of the wall to which the radio wave absorber is attached, a diffused reflection part that forms part of the wall is formed, and since a flat surface is formed at the bottom of the radio wave absorber, the radio wave absorber is not transmitted through the wall. Most of the generated electromagnetic waves are reflected toward the flat surface at the diffused reflection section in an inclined state. Therefore, this reflected wave is reflected without passing through the flat surface of the radio wave absorber and is gradually attenuated.

(Example) Hereinafter, the present invention will be described in detail based on the illustrated example of the present invention.

FIG. 1 is a perspective view showing the entire radio anechoic chamber of the present invention, and FIG. 2 is a cross-sectional view of the plane side of FIG. 1. This radio anechoic chamber, like a normal radio anechoic chamber, has a floor wall 11, front and rear walls 12, 13, left and right walls 14.
15 and a ceiling wall 16 define an accommodation space 17 inside. A transmitting source 18 and a receiving antenna 19 are provided in the accommodation space 17, and the receiving antenna 19 receives electromagnetic waves transmitted from the transmitting source 18.

A large number of square pyramid-shaped radio wave absorbers 20 are arranged on the inner surfaces of the front, rear, left and right side walls 12 to 15. Each radio wave absorber 20 is formed by impregnating foamed urethane with carbon powder as a radio wave absorbing material, and each of the illustrated radio wave absorbers 20 has a hollow lightweight structure. however,
The shape of these radio wave absorbers 20 may be various polygonal pyramid shapes or conical shapes other than the quadrangular pyramid shape.

FIG. 3 is a diagram showing a part of the radio anechoic chamber of the present invention, and this part is a part of two radio wave absorbers arranged inside the front wall 12 shown in FIGS. 1 and 2. shows. As shown in the figure, each radio wave absorber 20 has a plurality of radio wave absorbing plates 21 built into its bottom, and the bottom surface 22 is attached to the side wall 1.
It is a flat surface along 2. Instead of the hollow radio wave absorber 20 shown in the figure, a type of radio wave absorber that does not have a hollow part and is filled with a radio wave absorber may be used. In that case, the bottom surface will coincide with the bottom surface of the radio wave absorber 20.

Between the side wall 12 and the radio wave absorber 20, a metal diffuser reflection section 23 made of aluminum or the like is provided and becomes a part of the wall 12. This diffused reflection section 23 has a fifth
As shown in the figure, it has a semicircular cross section obtained by dividing the pipe in half, and is attached to the side wall 12 with the longitudinal direction of each half facing downward. The surface of these diffuse reflection parts 23 on the radio wave absorber 20 side is a circular diffuse reflection surface 24 .

FIG. 4 is a diagram showing the function of the diffused reflection section 23, in which the electromagnetic waves emitted from the source 18 in the radio anechoic chamber of the present invention fly in all directions other than the receiving antenna 19, and the radio wave absorber 2
Reach 0. A portion of the electromagnetic waves that have arrived will be reflected on the surface of the radio wave absorber 20, and the rest will be transmitted. Since the radio wave absorber 20 has a pyramidal shape such as a quadrangular pyramid shape, the reflected electromagnetic waves do not directly head toward the receiving antenna 19, but tilt toward the radio wave absorber on the inner surface of another wall. The transmitted electromagnetic waves are attenuated while their electrical energy is converted into thermal energy. This attenuation effect can be similarly obtained by the radio wave absorbing plate 21 provided at the bottom of the radio wave absorber 20. After passing through this radio wave absorption plate 21, as shown in FIG.
The electromagnetic waves that have reached the diffused reflection surface 24 of No. 3 are not reflected perpendicularly to the flat bottom surface 22, but are reflected obliquely toward the bottom surface 22 in most parts. When the light is reflected at an angle in this manner, it is reflected there without passing through the radio wave absorbing plate 22 located at the bottom of the radio wave absorber 20. This reflected wave is further reflected on the surface of the diffused reflection section 23 and is gradually attenuated. Therefore, the electromagnetic waves that have passed through the radio wave absorber 20 are reflected by the wall 12 and do not return to the radio anechoic chamber, and the electromagnetic waves pass through the radio wave absorber 20 and the diffused reflection section 2.
3, the radio wave absorber 20
The radio wave absorption effect in the radio anechoic chamber of the present invention including the diffused reflection section 23 became remarkable.

Although FIG. 3 shows a portion of the front wall 12, the rear wall 13 and the left and right walls 14, 15 have a similar structure as shown in FIG. Furthermore, the inner surface of the ceiling wall 16 has a similar structure. If the radio wave absorber 20 and the diffuse reflection part 23 are not provided on the bottom wall 11, a radio anechoic chamber in the broad sense described above can be obtained, and if they are also provided on the bottom wall 11, the radio wave absorber 20 and the diffuse reflection section 23 can be created in the narrow sense described above. A radio anechoic chamber will be obtained.

When the diffusely reflecting portions 23 are formed as part of the wall, since each diffusely reflecting portion 23 is formed of metal, external radio waves are prevented from entering from this portion, and these diffusely reflecting portions 23 are provided. It becomes unnecessary to make the wall itself metal, and it becomes possible to form the wall with reinforced concrete or the like.

FIG. 6 is a diagram showing another embodiment of the diffused reflection section 23. In this case, a large number of hemispherical diffused reflection surfaces 31 are formed on the metal plate 30 by plastic processing. I have to. Moreover, this hemispherical diffused reflection surface 31
Instead, a polygonal pyramid-shaped diffused reflection surface may be formed. The diffused reflection portion shown in FIG. 5 may have a zigzag shape.

(Effects of the Invention) As described above, according to the present invention, each wall forming the radio anechoic chamber is formed of a metal material, and at least one wall among the one floor wall, the four side walls, and the Nii wall A large number of cone-shaped radio wave absorbers each having a radio wave absorbing material are arranged inside the radio wave absorber, and a flat surface along the wall is formed at the bottom of each of the radio wave absorbers, and the wall on which the radio wave absorbers are arranged. A diffused reflection section is formed on the inner surface of the device, which has a diffused reflection surface that tilts and reflects the radio waves that have passed through the flat surface toward the flat surface. The light is reflected at an angle toward the flat surface by the diffuse reflection surface of the surface. When reflected from a tilted flat surface, the reflected wave is attenuated without passing through the radio wave absorber. This makes it possible to perform highly accurate measurement work without reflected waves reaching the receiving antenna in the radio anechoic chamber.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of the radio anechoic chamber of the present invention, FIG. 2 is a sectional view on the plane side of FIG. 1, and FIG. 3 is a part of the radio anechoic chamber of the present invention. FIG. 4 is a cross-sectional view showing the state of reflection of electromagnetic waves at the diffusely reflecting part, FIG. 5 is a perspective view showing the diffusely reflecting part shown in FIG. 3, and FIG. 6 is another embodiment of the present invention. It is a perspective view showing a diffused reflection part concerning an example. 11... Bottom wall, 12-15... Front, rear, left and right side walls, 1
6...Ceiling wall, 20...Radio wave absorber, 23...Diffuse reflection part, 31...Diffuse reflection part. Patent applicant Up Comma Co., Ltd. Agent
Patent Attorney 8 1) Mikio (1 idiot) No. 21!0 I5 Figure 3

Claims (1)

[Claims] A housing space is formed inside by a floor wall, front, left, right and left side walls, and a ceiling wall, and a transmission source for transmitting radio waves and a receiving antenna for receiving radio waves from this transmission source are provided in the housing space. In the radio anechoic chamber constructed as described above, each of the walls is formed of a metal material, and the inside of at least one wall of the floor wall, the four side walls, and the ceiling wall has a conical shape to absorb radio waves. A large number of radio wave absorbers having a material are arranged, a flat surface along the wall is formed at the bottom of each of the radio wave absorbers, and the radio wave absorbers are arranged on the inner surface of the wall on which the radio wave absorbers are arranged, and the radio wave absorbers pass through the flat surface. A radio anechoic chamber formed with a diffused reflection section having a diffused reflection surface that tilts and reflects radio waves toward the flat surface.