JPS6225920Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention generally relates to a radio wave shielding structure, and particularly relates to a radio wave shielding structure for an opening of a radio wave shielding room or an anechoic chamber having a window or a door.

(Prior art) A radio wave shielding room or a radio wave anechoic chamber has an opening such as a window or a door for the purpose of allowing users to enter and exit, just like in a general room. For effective use, it is necessary to sufficiently shield radio waves at the opening. Nowadays, with the increasing use of radio waves, there is an increasing demand for radio wave shielding chambers or anechoic chambers used at frequencies of 1 GHz or higher. Conventionally, as a radio wave shielding structure when used at a frequency of 1 GHz or higher, a means of contacting a projectile made of a good conductor has been used. This is achieved by a metal part provided at the opening of the radio wave shielding chamber or radio anechoic chamber, and a metal spring 2 provided in contact with the metal part of the opening on the door 1 that closes the opening, as shown in FIG. , radio wave shielding is performed. In this case, a slit 3 is formed in the metal spring 2 so that the entire metal spring 2 provided in the door 1 comes into contact with the metal part of the opening. Note that the slit is set to be cut off in terms of radio waves. That is, this conventional example has a structure that prevents radio waves from leaking to the outside through a small gap between the anechoic chamber and its door 1, or from entering the shielded chamber from the outside through the gap.

(Problems to be solved by the invention) However, in such a radio wave shielding structure, since the metal spring 2 is used to improve the metal contact of the door 1, an oxide film may be formed on the metal or If an insulator is interposed between the metal spring and the metal part, there is a problem that not only will the shielding characteristics be impaired, but also that the shielding characteristics of the slit will deteriorate when microwaves of 10 GHz or higher are generated.

Therefore, the present invention aims to solve the problems of the prior art.

(Means for Solving the Problems) The present invention forms a groove in the wall around the opening, in which a radio wave absorber is attached to the bottom and a pair of conductive elastic bodies are attached to the inner wall, and inside the groove. The present invention provides a structure for shielding an opening of a radio wave shielding chamber or an anechoic chamber, which is provided with a closing member having a metal piece inserted between the conductive elastic bodies.

(Function) According to the present invention, radio waves entering the opening are first shielded by one of the conductive elastic bodies, and the radio waves that are not shielded are absorbed by the radio wave absorber and further It is shielded by the other conductive projectile.

(Example) Hereinafter, the present invention will be described in detail based on an example with reference to the drawings.

Figures 2, 3, and 4 show an embodiment of the radio wave shielding structure according to the present invention. Figure 2 is a perspective view of a closing member such as a door, and Figure 3 is a perspective view of a closing member such as a door. FIG. 4 is a partially enlarged view of FIG. 3.

In these figures, 20 is a wall surface of a radio wave shielding room or a radio wave anechoic chamber, and this wall surface 20 has an opening 21 for providing a window or a door, etc.
A concave groove 11 is formed all around the peripheral edge. In the concave groove 11, a metal piece made of a good conductor is inserted so as to hold an insertion metal piece 12, which will be described later, received in the groove 11 under pressure when the opening 21 is closed with a closing member 10 (for example, a window or a door). A pair of resilient bodies (metal springs) 13a and 13b are provided near the entrance of the groove 11. A radio wave absorber 14 is made of a composite ferrite made by dispersing sintered ferrite or soft ferrite powder, or magnetic powder such as iron powder in rubber or resin, and is placed in the inner part of the concave groove 11.

On the other hand, when the opening 21 of the closing member 10 such as a window or door is closed, a protruding metal insert 12 that is received in the concave groove 11 of the wall surface 20 extends around the entire periphery of the member 10. You can receive it.

With the above configuration, if the opening 21 of the wall surface 20 is closed with the closing member 10, the joints at both ends will be connected to the fourth
The result will be as shown in the figure. That is, the inserted metal piece 12
is pressed at its side by the elastic bodies 13a and 13b, and its tip abuts against the radio wave absorber 14. Therefore, the radio waves (A) coming from between the closing member 10 and the wall surface 20 are first blocked by the bombardment body 13b,
As a result, the unshielded radio waves (B) are absorbed by the radio wave absorber 14 and are further shielded by the bombardment body 13a. Note that the insertion metal piece 12 does not necessarily need to be in close contact with the radio wave absorber 14, and even if there is a gap of several mm between them, the reduction in the shielding effect is relatively small due to the magnetic field effect of the magnetic material.

Figure 5 shows an experimental example of the radio wave shielding structure according to the present invention, which uses a stainless steel insert metal piece, a beryllium copper bullet, and a radio wave absorber made of a composite of carbonyl iron and rubber. (The vertical axis is the shielding characteristic (dB), the horizontal axis is the frequency).

In Figure 5, curve A is the shielding characteristic of the structure according to the present invention, B is the shielding characteristic when no radio wave absorber is used, and C is the vinyl piece (0.3 m thick) between the inserted metal piece and the bullet body. /m) and without using a radio wave absorber, D
is the shielding property when a vinyl piece (thickness 0.3m/m) is sandwiched between the inserted metal piece and the bullet body and a radio wave absorber is used, and E is the shielding property when only the radio wave absorber is used and no bullet body is used. The shielding characteristics are shown below. As is clear from the figure, the shielding structure according to the present invention does not show any significant deterioration in shielding characteristics even at frequencies above 10 GHz, and works extremely effectively. As is clear from curve D, even when an insulator is present, the shielding characteristics hardly deteriorate.

(Effects of the invention) As explained above, the radio wave shielding structure of the invention is
There is almost no deterioration in shielding characteristics due to insulators, etc.
Furthermore, it has the effect of having good shielding characteristics even at frequencies of 10 GHz or higher.

[Brief explanation of the drawing]

Figure 1 shows a conventional example of a radio wave shielding structure, Figures 2 and 3
4 and 4 show an example of the radio wave shielding structure according to the present invention, and FIG. 5 shows an experimental example using the radio wave shielding structure according to the present invention. 10; Closing member; 11; Concave groove; 12; Insert metal piece; 13a, 13b; Elastic body; 14; Radio wave absorber.

Claims (1)

[Scope of utility model registration request] A groove in which a radio wave absorber is attached to the bottom and a pair of conductive elastic bodies are attached to the inner wall is formed on the wall surface around the opening, and an inserted metal piece is inserted into the groove and held between the conductive elastic bodies. 1. An opening shielding structure for a radio wave shielding chamber or a radio anechoic chamber, characterized in that it is provided with a closing member.