JPH0453198A - Radio wave anechoic room - Google Patents

Abstract

PURPOSE:To sufficiently absorb a primary reflection wave by forming an oblique surface inclined toward a transmission source at a position where primary reflection of a radio wave from the source to a reception antenna occurs at least one wall of the sidewall and a ceiling of a radio wave anechoic room in which a ferrite absorber is adhered to the inner surface. CONSTITUTION:A tilelike ferrite absorber is adhered to the sidewall 2 of a radio wave anechoic room 1 and the inner surface of a coiling. An oblique surfaces 5 inclined toward a transmission source 3 is provided at a position where a primary reflection from the source 3 to a reception antenna 4 occurs on one or both of the sidewall 2 and the ceiling of the room 1. The absorber 6 is adhered to the surface 5. Since the surface 5 is provided at the position where the primary reflection occurs, the radio wave radiated from the source 3 in this direction is incident perpendicularly to the absorber 6 to be effectively absorbed and attenuated. Thus, influence of the primary reflection wave can be avoided to enhance correlation to an open site.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an anechoic chamber used for indoor characteristic testing of various electrical devices.

(Prior art) Measurement of magnetic noise of electrical equipment 1 is carried out at an oven site of a predetermined size with no surrounding buildings that reflect radio waves. However, in urban areas, the installation location of such an oven site is difficult to secure. For this reason, in Japan, anechoic chambers, which can provide a radio wave space similar to oven sites inside factories, are becoming popular.

The larger version of this anechoic chamber has large biramint-like absorbers attached to the side walls and ceiling of the room to prevent electromagnetic waves from being reflected from the walls. However, recently, small anechoic chambers with a limited frequency range have rapidly become popular.

Such a small anechoic chamber was developed, for example, in Japanese Patent Application Laid-Open No. 64-160.
As shown in Publication No. 38, tile-shaped ferrite absorbers are pasted on side walls, ceilings, and even floors in some cases as radio wave absorbers. range). However, since the anechoic chamber is box-shaped,
As shown in FIG. 4, it is inevitable that the electromagnetic waves radiated from the transmission source (3) undergo primary reflection on the wall or ceiling surface and enter the receiving antenna (4). Due to its operating principle, ferrite absorbers have a characteristic that the absorption rate of obliquely incident electromagnetic waves is extremely poor, so it is almost impossible to expect absorption of primary reflected waves, and the correlation with the oven site may worsen, and ferrite absorbers There was a problem in that the function of the anechoic chamber was not demonstrated even in the operating range of .

(Problem to be Solved by the Invention) The present invention solves these conventional problems and provides an anechoic chamber that can sufficiently absorb primary reflected waves using a ferrite absorber. It was perfected for the purpose of

(Means for Solving the Problems) The present invention, which has been made to solve the above problems, transmits radio waves from a transmitting source to a receiving antenna on at least one side wall or ceiling of an anechoic chamber with a ferrite absorber attached to the inner surface. It is characterized by a structure in which an inclined surface is formed at the position where the primary reflection occurs and is inclined toward the transmission source, and the radio waves undergoing the primary reflection are perpendicularly incident on the ferrite absorber on the surface of the inclined surface. It is something.

The present invention will be explained in detail below with reference to illustrated embodiments.

(Example) In the first example shown in FIG. A transmitting source such as a test equipment (4) is a receiving antenna.In the present invention, the side wall (2) of such an anechoic chamber (1)
An inclined surface (5) inclined toward the transmission source (3) is provided at a position where primary reflection from the transmission source (3) to the reception antenna (4) occurs on one or both wall surfaces of the ceiling and the ceiling. . A ferrite absorber (6) is also pasted on the surface of this inclined surface (5).

In the second embodiment shown in FIG. 2, the shape of the back surface of the slope (5) is somewhat different, and in the third embodiment shown in FIG. 3, the back surface of the slope (5) has a continuous width. It is formed in the narrow part. Further, such an inclined surface (5) may be movable in the longitudinal direction of the anechoic chamber.

In either embodiment, the primary reflected wave is perpendicularly incident on the ferrite absorber (6) on the surface of the inclined surface (5), and the primary reflected wave is sufficiently absorbed and attenuated. Since the surface (5) is for absorbing the primary reflected wave, the sloped surface (5) does not fit inside the line connecting the maximum dimension line of the transmitting source (3) and the maximum dimension line of the receiving antenna (4). This is to ensure that the direct wave from the transmitting source (3) to the receiving antenna (4)
4). Further, as long as this condition is satisfied, it is desirable that the dimensions of the inclined surface (5) be approximately the projected dimensions of the transmission source (3). This is the transmission source (3
This is to ensure that the primary reflected wave hits the inclined surface (5) no matter where the noise source is located.

(Function) The radio anechoic chamber of the present invention configured as described above has transmitter 5 (3
) to the receiving antenna (4), the radio waves radiated in this direction from the transmitter ei (3) are absorbed by the ferrite absorber (6) on the inclined surface (5). ), it is surely absorbed and attenuated. Therefore, according to the present invention, the influence of primary reflected waves can be avoided, and the correlation with oven sight can be improved.

Furthermore, if the inclined surface (5) is made movable as described above, the inclined surface ( 5) can be adjusted, and the function as an anechoic chamber can be dramatically improved.

(Effects of the Invention) As is clear from the above description, the present invention is an anechoic chamber that uses a ferrite absorber, but can sufficiently absorb primary reflected waves, and improves the correlation with the oven site. As a result, it will greatly contribute to the development of industry as an anechoic chamber that eliminates the problems of conventional methods.

[Brief explanation of the drawing]

1, 2, and 3 are horizontal cross-sectional views showing embodiments of the present invention, and FIG. 4 is a horizontal cross-sectional view showing a conventional anechoic chamber. (2): side wall, (3): transmitting source, (4): receiving antenna, : inclined surface, (6) biferrite absorber.

Claims (1)

[Claims] 1. Primary reflection of radio waves from the transmitting source (3) to the receiving antenna (4) occurs on at least one wall surface of the side wall (2) or the ceiling of the anechoic chamber whose inner surface is covered with a ferrite absorber. At the position, an inclined surface (5) is formed that is inclined toward the transmission source (3), and the radio waves that cause primary reflection are directed to the inclined surface (5).
An anechoic chamber characterized by having a structure in which the light is incident perpendicularly to the ferrite absorber (6) on the surface of the ferrite absorber (6). 2. The anechoic chamber according to claim 1, wherein the position of the inclined surface (5) is movable in the longitudinal direction of the anechoic chamber.