JPH0335630A - Indoor communication equipment - Google Patents

Abstract

PURPOSE:To reduce transmission distortion by providing a first antenna giving directivity to a radio wave radiated from a first radio equipment in a radioactive substance container and a radio wave absorber which absorbs the radio wave reflected from the wall of the radioactive substance container into the outer peripheral area of a passing hole and which can be moved and opened. CONSTITUTION:At the time of executing communication between the first radio equipment 1 arranged in the radioactive substance container 4 and a second radio equipment 2 which is separated from the radioactive substance container 4 by metallic shield plates 5 and which is arranged in an external part, the beam of the radio wave to be radiated is set sharp by making the directivity of the first antenna 1a of the first radio equipment 1 to be sharp. Furthermore, the radio wave absorber 8 which absorbs the reflected radio wave which occurs by radiating the radio wave from the antenna 1a on the wall 7 of the radioactive substance container 4 in the periphery of the passing hole 6 in the middle of a radio wave transmission line and which can be moved and can be opened is provided. Thus, reflection in the radioactive substance container 4 can be prevented and communication with small transmission distortion can be executed.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a communication device that communicates between the inside of a radioactive material storage facility and the outside of the storage facility by passing radio waves through a hole made in a part of a metal shielding plate of a radioactive material storage facility. For the purpose of providing a communication device that absorbs reflected radio waves generated in the transmission path and reduces transmission distortion, a metal shield is provided between the first radio device installed inside the radioactive material storage and the radioactive material storage. In a communication device that communicates with a second radio device that is installed separated by a board through a passage hole provided in the metal shielding plate, a first radio device that gives directionality to radio waves emitted from the first radio device. An antenna and a radio wave absorber that absorbs radio waves reflected from the wall of the radioactive substance storage in the outer peripheral area of the passage hole and that can be moved and opened/closed are provided.

[Industrial application field]

The present invention relates to a communication device that transmits radio waves through a hole formed in a part of a metal shielding plate of a radioactive material storage facility to communicate between the inside of the radioactive material storage facility and the outside of the storage facility.

[Conventional technology]

FIG. 5 is a diagram showing an example of a conventional device configuration.

In the figure, 1 is the first radio device, 1a is the first antenna 1 of the first radio device 1, 2 is the second radio device, and 2a is the second radio device 2.
3 is a radiation source, 4 is a radioactive material storage, 5 is a metal shielding plate, 6 is a radio wave passage hole provided in the metal shielding plate 5, and 7 is a wall outside the radioactive material storage 4. Note that d is the radioactive material storage 4 of the first wireless device 1.
, and l is the transmission distance between the first antenna la and the metal shielding plate 5.

Radiation 'a3 is surrounded by a wall 7 and is contained in a radioactive material storage 4 which has a shielded space that cannot be accessed by humans,
A first wireless device 1 installed inside the radioactive material storage 4 to a second wireless device 2 installed outside the radioactive material storage 4
When communicating between the first antenna 1a and the second antenna 2a, generally a passage hole 6 for passing radio waves is provided in a part of the metal shielding plate 5 at a transmission distance e from the first wireless device 1. When opened, the emitted radio waves 9 from the first wireless device 1 are transmitted to the second wireless device 2 for communication. jm in this case
The radio waves irradiated to the surrounding area other than the passage hole are reflected within the radioactive material storage 4, especially when the first wireless device 1 is moved by the moving distance d, and so-called multiple reflections occur, which changes the transmission characteristics of the radio waves. produces echo distortion. The maximum deviation of the amplitude characteristics, phase characteristics, and delay characteristics due to this echo is: amplitude p-p# 2 r (x100%) phase p-p#
2 r (rad) Group delay time 2rτ (seconds) is given. However, the amplitude p-p is the difference between the maximum value and the minimum value of the amplitude, the phase pp is the difference between the maximum value and the minimum value of the phase, r is the reflection coefficient, τ is the delay time (12/co, Co is the speed of light ), and l is the transmission distance.

Because of this echo distortion, for example, when two signals, such as a video signal and an audio signal, are transmitted using a frequency modulation method using a single radio wave, the video signal is distorted, which increases distortion noise in the audio band as well. It becomes like this.

[Problem to be solved by the invention]

Therefore, there is a problem in that multiple reflections occur due to radio waves irradiated around areas other than the passage hole, causing distortion in transmission characteristics.

An object of the present invention is to provide a communication device that absorbs reflected radio waves generated in a radio wave transmission path and reduces transmission distortion.

[Means to solve the problem]

In the present invention, as shown in FIG.
The metal shielding plate 5 is provided with a space between the first wireless device 1 installed inside the radioactive substance storage 4 and the second wireless device 2 installed so as to be isolated by a metal shielding plate 5. In a communication device that performs communication through a passage hole 6, a first antenna la that gives directionality to radio waves emitted from the first wireless device 1, and a wall 7 of the radioactive substance storage 4 in an outer peripheral area of the passage hole 6 are provided. This structure absorbs radio waves reflected from the antenna and further includes a radio wave absorber 8 that can be moved and opened/closed.

(Function) In the present invention, as shown in FIG. When communicating with the second radio device 2 through the passage hole 6, the directivity of the first antenna 1a of the first radio device 1 is narrowed to sharpen the emitted radio wave beam, and the radio wave transmission path A radio wave absorber 8 is provided around the passage hole 6 on the way to absorb reflected radio waves generated by the radio waves radiated from the first antenna 1a to the wall 7 of the radioactive material storage 4, and has a movable and open/close structure. I am trying to set it up.

Therefore, communication without reflection on the radio wave transmission path is possible.

[Embodiment] FIG. 1 is a diagram showing a first embodiment of the apparatus configuration of the present invention. In the figure, 1 is the first radio device, 1a is the first antenna 1 of the first radio device 1, 2 is the second radio device, 2a is the second antenna of the second radio device 2, 3 is the radiation source, and 4 is the radioactive Material storage, 5 is a metal shielding plate, 6 is a radio wave passage hole provided in the metal shielding plate 5, 7 is an outer wall of the radioactive material storage 4, and d is inside the radioactive material storage 4 of the first radio equipment l. The moving distance l is the transmission distance between the first antenna 1a and the metal shielding plate 5. Note that 8 is a radio wave absorber used in the present invention.

As explained in the conventional example shown in FIG. 5, several radiation sources 3 are surrounded by a wall 7 and are housed in a radioactive material storage 4 that has a shielded space that cannot be accessed by humans. When communication is performed between the first solid line device 1 installed inside the radioactive material storage 4 and the second wireless device 2 installed outside the radioactive material storage 4 between the respective first antennas 1a and second antennas 2a, generally is the transmission distance l from the first wireless device 1
A passage hole 6 for passing radio waves is formed in a part of the metal shielding plate 5, and the emitted radio waves 9 from the first radio device 1 are transmitted to the second radio device 2 for communication.

In such a configuration, in the present invention, as shown in FIG. 1, first, the radio wave beam is narrowed down as much as possible by the first antenna la to make the radiation pattern from the first antenna la as sharp as possible. Furthermore, by providing a radio wave absorber 8 made of, for example, urethane rubber containing carbon particles, around the passage hole 6 provided in the metal shielding plate 5, the radio wave energy due to reflection is absorbed and transmitted from the metal shielding plate 5. The reflected radio waves IO are suppressed.

In FIG. 1, when the transmission distance l between the first wireless device 1 and the metal shielding plate 5 moves away from the moving path #d, the radio wave beam starts to spread. In this case, reflection from sources other than the metal shielding plate 5 becomes unavoidable. A method for preventing this by narrowing down the radio wave beam of the first antenna la has physical, cost, and shape limitations.

For this reason, it is also necessary to absorb the expanded portion of the radio wave beam during the transmission of radio waves, and to protect the radio wave absorber 8 from radiation.

FIGS. 2(A), 2(B), 2(C), and 2(D) each show an example of the structure of a radio wave absorber used in the present invention.

First, FIG. 2(A) shows a space absorber in which carbon-like particles are coated on triangular plastic rubber or the like and fixed to a metal shielding plate 5 in order to form a radio wave absorber 8. It has a tapered shape to match the impedance of the radio wave absorber 8 and the spatial impedance. In this case, you can replace it with a better one with less reflection of radio waves, but the shape will be three-dimensional and larger.

Next, in FIG. 2(B), paint is applied to the surface of the metal shielding plate 5, and a radio wave absorbing substance is included in the paint.
It is designed to attenuate the high frequency current flowing through the metal surface, and although its attenuation characteristics are not very good, it has the advantage of being able to be made thinner. Note that the radio wave absorber 8 shown in FIGS. 2(A) and 2(B) has the disadvantage that it is easily exposed to radiation and easily deteriorates.

FIGS. 2(C) and 2(D) show a horn antenna in which a metal shielding plate 5 is processed into a horn antenna shape, and a large number of horn antenna openings 21 each having a width of approximately one wavelength or more are arranged. It has a structure in which a radio wave absorber 8 such as ferrite is fitted into the center of the opening 21, and is sized to cover the radio wave irradiation area of the first antenna la. Note that FIG. 2(C) shows a front view, and FIG. 2(D) is a sectional view taken along the (1)-(1') plane of FIG. 2(C). The radio wave passage hole 6 is provided so as to be located approximately at the center of the large number of horn antenna openings 21. This structure has the advantage of being able to be used permanently.

FIG. 3 is a diagram showing a second embodiment of the device configuration of the present invention, with FIG. 3(A) being a front view and FIG. 3(B) being a side view. If the distance between the first antenna la and the passage hole 6 of the metal shielding plate 5 (not shown) is long, a movable radio wave absorbing device having a loop-shaped passage hole 36 in the middle between the first antenna la and the metal shielding plate 5, for example, An example is shown in which the body 38 is placed so that the first wireless device 1 can move freely so that it does not interfere with the transmission of radio waves, and the reflected radio waves 10 are absorbed.

Furthermore, FIG. 4 shows a third example of the device configuration of the present invention, and is an example using an oblique reflecting plate 45. The radio waves from the first antenna 1a of the first radio device 1 near the scattered radiation source 3 are sharp beams, and therefore the emitted radio waves 9 are all transmitted through the passage hole 46 provided in the diagonal reflector 45. Ru. On the other hand, the beam width of the reflected wave 10 from around the passage hole 6 provided in the metal shielding plate 5 is wide, and therefore most of it is reflected downward by the diagonal reflector 45 and is reflected by the radiation protection plate 49 made of a lead plate. Most of the reflected energy is absorbed by the radio wave absorber 48 provided above. Therefore, it is not affected by reflection during transmission of radio waves.

〔Effect of the invention〕

As is clear from the following description, according to the present invention, reflection at the radioactive material storage can be prevented, so communication with low transmission distortion can be realized, and broadband transmission can be achieved. Furthermore, indoor communication is possible without the need to cover the entire wall with radio wave absorbers.

[Brief explanation of drawings]

Figure 1 is a diagram showing a first embodiment of the device configuration of the present invention. Figure 2 (A) to (D) is a diagram showing a structural example of a radio wave absorber used in the present invention. Figure 3 is a diagram showing a first embodiment of the device configuration of the present invention. FIG. 4 is a diagram showing a third embodiment of the device configuration of the present invention, and FIG. 5 is a diagram showing an example of the conventional device configuration. In the figure, l is the first radio device, la is the first antenna, 2 is the second radio device, 2a is the second antenna 3 is the radiation source, 4 is the radioactive material storage, 5 is the metal shielding plate, 6 is the passage hole, 7 walls, 8 radio wave absorbers, are shown. beckoning θ, pull; Saiji's Shishiman's enemy Y Akutamaro 49 mosquito village so fat t1 building 49 (B) (C) 4 岑zamei t-1 ノUt
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Claims (1)

[Claims] A first wireless device (1) installed inside a radioactive material storage (4) and a first radio device (4) installed with a metal shielding plate (5) separating the space between the radioactive material storage (4) and the radioactive material storage (4). Two radio devices (2)
a first antenna that imparts directionality to radio waves radiated from the first wireless device (1); (1a) and the passage hole (6)
A radio wave absorber (8) that absorbs radio waves reflected from the wall (7) of the radioactive material storage (4) and is movable and openable is provided in the outer peripheral area of the radioactive material storage (4). indoor communication equipment.