JPH0781334B2 - A structure for housing radio wave equipment - Google Patents

Description

The present invention relates to an improvement of a building having a so-called large room structure such as a factory, office, gymnasium, and venue for entertainment, and in particular, mutual radio communication or radio waves such as telemetry inside the building. The present invention relates to a device for shielding the application from the outside and coexistence of free wireless communication between the inside and the outside.

Recently, it has been widely practiced to use wireless communication, which has no restraint, instead of wire communication via cables, for telephone calls, measurements, and data transmission, even in the case of short-distance communication within the building as described above. There is. The signal media that can be used include light, ultrasonic waves, radio waves, electrostatic or electromagnetic induction, but in terms of technical perfection, reliability, freedom of design, and large transmission volume, etc. There is nothing better than radio waves for evaluation. However, the biggest problem with radio waves is interference due to interference or interference, which requires consideration of both the receiving and emitting phenomena, but if we consider the reversibility of the electromagnetic field phenomenon, both are essential. Are common to all. That is, it is generally difficult to share one frequency for multiple purposes in free space. This is because the different systems use the same frequency but do not interfere with each other, or the interference can be harmless, such that they can be used either temporally or spatially. It is not only a problem, but is widely treated as a general radio wave administrative problem. Furthermore, not only the electromagnetic waves actually emitted intentionally, but also unintentional emission, that is, the problem of electromagnetic environmental pollution by various electronic devices is actually involved.

Therefore, if a group of radio wave-using devices always operates while staying in a certain closed space even if it moves, in other words, wireless communication is performed, but the other party is always in a certain space. In some cases, the space is intentionally closed by the wall of the conductor or the electromagnetic wave absorber in order to block both the disturbance from the outside world and the disturbance to the outside world. This is, for example, a big room, a hall,
This method is often used when you want to use a telemetry system, a paging system, a cordless telephone, a wireless microphone, or a wireless LAN (local area network) on a floor of a building without interfering with others.

However, according to such a "shielded room" method, of course, intentionally performing wireless communication with the outside from the space is also hindered at the same time. This is very inconvenient in some cases. For example, both radio and television may not be available, or the sensitivity may be poor and the sound quality and image quality may be severe. There may be a case where the LAN utilization system itself wants to establish another wireless link with a wireless station or communication hygiene in the outside world at the same time. In such a case, a dedicated antenna or wireless transceiver must be provided outside this space, and communication with it must be performed using a dedicated cable or the like.

The present invention is intended to eliminate such inconvenience, and in particular, in intentionally “shielding” a certain target closed space as described above, the effect of the shield is intentionally frequency-selective. In addition, operate the telemetry system or LAN in the frequency band that has the shield effect, and operate the wireless communication with the outside world in the frequency band that does not have the shield effect or the electromagnetic wave can be exchanged without any practical interference. The present invention relates to a building that accommodates radio wave utilization equipment that can be used in various ways.

In order to realize the wavelength-selective "shield room", in the present invention, at least a part or all of the partition walls above the ground of the shield room are made of a wavelength-selective material and / or structure.

FIG. 1 shows an embodiment of a wall material for realizing such a system. In this, the point from an electromagnetic wave standpoint is that the conductor 11 has innumerable small openings 12, and such punching plate or In an extreme case, the wire mesh-like conductor is made to cover the target space without interruption.
The electromagnetic wave permeability of such a punching plate or wire mesh is most roughly described as the size of the holes or the mesh.
In particular, it appears to be almost transparent at short wavelengths whose major axis is more than half a wavelength or whose perimeter is more than a wavelength, and it is almost or completely completely continuous at long wavelengths that are less than that wavelength. Looks equivalent to a conductor. Therefore, for example, if the diameter of the holes or mesh is set to about 10 cm, 1.
Around 5 GHz, a closed space made of a translucent wall above that and a reflective wall below that can be realized. As a result, a LAN using a frequency of 800 MHz to 1 GHz or less inside the closed space
And telemetry can be performed without interference between inside and outside, while 2GHz
In the above, it is possible to establish a wireless link with the communication satellite without being obstructed by the wall. Further, natural light and far infrared rays from the outside world can pass through the wire net almost freely, so that it does not hinder the lighting of the target space. In this case, this wire mesh is used in combination with glass or a transparent plastic plate or film.

FIG. 2 shows another embodiment, in which the wall has a multi-layer structure, in particular at least two substances whose ε or μ or both are significantly different from each other are alternately layered. Have a structure. That is, the first substance 21 and the second substance
Since the wave impedance of 22 is significantly different from that of electromagnetic waves, such a periodic structure in the thickness direction produces peaks and valleys that are remarkable in its reflection and transmission properties. This principle is known as a so-called dichroic mirror principle, and is optically widely used as a bandpass filter or a bandstop filter. For example, when it is desired to set the stop band near a certain frequency, the electromagnetic thickness (determined by the propagation velocity) of each layer in the vicinity of the frequency is set to about 1/2 wavelength. If foamed polyethylene is the first substance and dense (non-foamed) polyethylene is the second substance, the former is almost equivalent to air, and the latter has a significantly larger ε (approximately 2.3).
Therefore, it can effectively act as a dichroic mirror by the above method. In this case, the first reflection band is approximately 8G
The thickness of the above first substance is about 1.9c when it is measured at around Hz.
m, the thickness of the second material is about 1.3 cm because the wavelength is shortened to about 2/3. When several layers or dozens of layers of these materials are stacked, they show good reflectivity and blocking property around 8GHz, and on the contrary, each layer looks at 1/4 wavelength and its odd multiple, 4
It is transparent in the GHz and 12 GHz bands. Therefore, low power telemeters and wireless LANs can be used without interfering with the outside world inside a closed room with such a multi-layered structure, while the 4GHz band commonly used for satellite communication and satellite broadcasting. And, in the 12 GHz band, the communication and broadcast can be received almost anywhere. Each layer of this structure is 1/4
It is sufficiently transparent even in the low range below 4 GHz, which appears below the wavelength,
Practically no interference with UHF or VHF TV, FM broadcasting or medium or short wave radio.

Frequency selective reflection and transmission blocking can also be achieved by arranging a myriad of resonators in the wall. That is, FIG. 3 shows a third embodiment of the present invention, in which the wall 30 is made of a material such as foamed polyethylene that does not substantially interfere with electromagnetic waves. However, it contains innumerable resonators 31 in it.
In this case, the resonator 31 is a ring, and the stop frequency band is generated in the frequency region where the circumference is one wavelength or the diameter is half a wavelength. Instead of a ring, a square or other ring-shaped or ring-shaped conductor which may form a closed loop is innumerably distributed in the wall 30 in volume distribution. 8G for example
When the Hz band is used as the blocking reflection band, a ring made of copper foil having a thickness of about 25 to 50 μm and an average diameter of about 1.8 cm is evenly distributed in the foamed polyethylene wall having a thickness of about 30 cm.

Such a copper foil ring can be easily obtained, for example, by etching or punching a printed circuit board. However, it does not necessarily have to be copper, and may be iron or the like. It may be obtained by punching a thin iron plate with copper plating. Further, by plating silver or gold on copper, the Q as a resonator of its own and the weather resistance can be improved.

The distribution density of the rings is preferably such that the average distance between the rings is approximately equal to their diameter, provided that the rings do not contact each other. In addition, it is convenient in manufacturing that the distribution pattern has regularity. In this case, the direction of the ring axis is approximately aligned with the traveling direction of the electric wave, which is aimed at blocking (parallel is ineffective). However, even if they are distributed in random directions without such efforts, essentially the same effect can be obtained by doubling the distribution density. Unit resonators that can be used as spatially distributed resonators for this purpose include, in addition to rings, rods, disks, spheres, or spiral conductor fragments as shown in FIG. 4a, or as shown in FIG. 4b. It is possible to effectively use a pair of two conductor pieces which are used as loading capacitors and which are entwined with an inductor.

A wall having wavelength-selective reflection / transmission characteristics that can be used for implementing the present invention can also be realized by utilizing a skin effect of a conductor. That is, in general, in order for electromagnetic waves to be reflected well, the thickness of the conductor surface is the so-called skin depth value, f = frequency μ = permittivity of conductor (assumed to be the same as free space) η = conductivity (reciprocal of volume resistivity) C = thickness of light Must be sufficiently thicker than value, conversely thinner conductor surface than this In the case of, there is almost no reflection and it is transparent. In the fourth embodiment of the present invention which utilizes such a property, a hemispherical structure 50 having a dome-shaped membrane as shown in FIG.
By maintaining a slight pressure difference between the inside and the outside, the shape suitable for building is maintained by maintaining a slight difference in pressure between the inside and outside. In using the baked product, a thin layer of aluminum having a thickness of about 3 μm is additionally laminated, or the film is deposited by vapor deposition, sputtering, combined use of chemical plating and electric plating, or the like. Since the conductivity of aluminum is about 3 × 10 ⁻⁶ Ω · cm, this gives approximately 1 GHz as the cutoff frequency derived from the skin effect. In other words, in an air dome such as a film with such a thin conductive layer, electromagnetic waves of approximately 2 to 3 GHz or more are low power telemeters without causing interference between the inside and outside,
It can be used independently for LAN, etc., but at frequencies below 300-500MHz, wireless communication can be performed between inside and outside without interruption. In this type of air dome, the transparency and air permeability of the film may be expected as one of important properties, but in order to prevent the conductive film from meeting the requirement, a fine grid pattern is required. To ensure breathability and translucency at the holes. If the pitch of the grid is set to about a few mm or less, it looks like a uniform conductor up to several tens of GHz, so it does not contradict the above point. In this case, it should be noted that the conductivity to be applied is the average conductivity of the lattice.

As described above, according to the present invention, the target closed space is shielded in a certain frequency band and is not shielded in another frequency band. Therefore, in the former frequency band, low power telemetry or wireless communication can be performed without mutual interference with the outside world. This is convenient because it can be used for electromagnetic wave applications such as LAN expression, and wireless transmission between the outside frequency and the outside frequency is possible in the latter frequency band.

[Brief description of drawings]

FIGS. 1, 2, 3, and 5 show different embodiments of the present invention, and FIG. 4 shows some of the elements in the embodiment described with reference to FIG.

Claims (1)

[Claims] 1. The inside and outside partition walls on the ground have frequency-selective reflection and transmission characteristics for radio waves, and the radio wave utilization equipment accommodated therein is used to construct the inside and outside of the building by using the frequency band in the transmission range. Between the wireless communication between them, and also by using the frequency band of the stop band or the reflection band, the electromagnetic wave application inside the building can be performed without being disturbed by the external electromagnetic field, or conversely, without being disturbed. A building that divides an enclosed space, characterized by being pushed.