JP2003332785A - Radio wave propagation space - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio wave propagation space, e.g. a microwave darkroom, having an inexpensive and simple structure as compared with prior art, and to provide a stable radio communication environment capable of preventing multiplex reflection. <P>SOLUTION: A radio wave propagation room is a space closed by a wall part 11 having a parabolic cross-section, a wall part 12 having a parabolic cross-section and facing the wall part 11, a planar ceiling part 13, a planar floor part 14 facing the ceiling part 13, a planar wall part 15, and a planar wall part 16 facing the wall part 15. When a radio wave is transmitted from a transmitting point T at the focus on the parabolic plane of the wall part 11, it is reflected on the wall part 11 and propagates in parallel with the ceiling part 13 and the floor part 14 to reach the wall part 12 where it is reflected. Furthermore, all transmitted radio waves can be received and absorbed at a receiving/absorbing point R located at the focus on the parabolic plane of the wall part 12. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN, for example.
The present invention relates to a radio wave propagation space such as a room or an anechoic chamber, which is suitable for use.

[0002]

2. Description of the Related Art In recent years, a LAN has been used to share a database with each other when a plurality of personal computers are used in an office room, and in particular, a wireless LAN that does not require wiring has become widespread.

For example, in an indoor wireless LAN, data communication is performed between an access point device, which is a wireless base station connected to a server device, and a wireless communication terminal device, which is connected to each personal computer, via a wireless section. Done. In the propagation of this radio wave, not only direct wave propagation, but also reflected waves occur due to the wall surface of the room, etc., and multiple reflections often occur in which the reflection occurs multiple times.

[0004]

In the room where the above-mentioned multiple reflection occurs, the direct wave and a plurality of reflected waves interfere with each other, and the electric field strength may be significantly weakened in a certain area of the room. As a result, there is a problem that it may be difficult to establish a wireless communication connection between the access point and the wireless communication terminal device.

In order to solve this problem, an electromagnetic wave absorber may be provided on the entire inner wall of the room, such as an anechoic chamber, but in this case, the manufacturing cost becomes extremely high.

An object of the present invention is to solve the above problems and to provide a radio wave propagation space such as an anechoic chamber which is cheaper and has a simpler structure than the prior art.

Another object of the present invention is to solve the above problems and to provide a radio wave propagation space capable of preventing the above-mentioned multiple reflections and providing a stable wireless communication environment. It is in.

[0008]

A radio wave propagation space according to a first aspect of the present invention includes at least two first and second reflecting surfaces each having a parabolic section or a parabolic surface having one focal point, and When a radio wave is transmitted from the focus of the first reflecting surface,
A radio wave absorber that is provided at the focal point of the second reflection surface and that receives and absorbs the transmitted radio wave.

In the radio wave propagating space according to the first aspect of the invention, preferably, each of the reflecting surfaces has a plurality of reflecting surface portions connected to each other. Further, it is preferable that when the radio wave is transmitted from the focus of the first reflecting surface, a means for limiting a transmission angle is further provided so that the transmitted radio wave is reflected by the first reflecting surface. Characterize.

The space for radio wave propagation according to the second invention is the first space.
And at least one reflecting surface having an elliptical cross section or an ellipsoidal rotator surface having a second focus, and a second focal point of the reflecting surface when a radio wave is transmitted from the first focal point of the reflecting surface, A radio wave absorber that receives and absorbs the transmitted radio wave is provided.

In the radio wave propagating space according to the second aspect of the present invention, preferably, the reflecting surface has a plurality of reflecting surface portions connected to each other. Further, it is preferable that when the electric wave is transmitted from the first focal point of the reflecting surface, a means for limiting a transmission angle is further provided so that the transmitted electric wave is reflected by the reflecting surface. .

Further, in the radio wave propagating space according to the first and second inventions, preferably, the space is a room or an anechoic chamber.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a perspective view showing the shape of a radio wave propagation room according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a cross section taken along the XY plane of FIG. It is a figure.

In FIG. 1, the radio wave propagation room according to the first embodiment is provided with a wall 11 having a parabolic cross section and a wall 1.
1, a wall 12 having a parabolic cross section, a ceiling 13 having a planar shape, a floor 14 having a planar shape facing the ceiling 13, a wall 15 having a planar shape, and a wall 15 opposing the wall 15. It is a space enclosed by the planar wall portion 16. Here, each of the walls 11 and 12 has a parabolic surface formed by extending a parabolic cross section over a predetermined length. In FIG. 1, the plane parallel to the ceiling portion 13 and the floor portion 14 is X.
The Z plane is used, and the plane parallel to the walls 15 and 16 is the XY plane.

In the radio wave propagation room configured as described above, the transmission point T located at the focal point of the parabolic surface of the wall portion 11
2, the radiation limiting azimuth angle (in the vertical plane that is the XY plane) capable of being reflected by the wall portion 11 as shown in FIG.
Then, when transmitting using, for example, a directional antenna so as not to radiate to the ceiling portion 13, the floor portion 14, and the wall portion 12, the transmitted radio wave is reflected by the wall portion 11, and then the XZ plane, that is, the ceiling portion 13 And propagates parallel to the floor 14 and reaches the wall 12. Next, the transmitted radio wave is reflected by the wall portion 12, and all the reflected radio waves are received at the reception absorption point R (where the Z coordinate of the position of the transmission point T is located at the focal point of the parabolic surface of the wall portion 12). The radio wave absorber provided at the reception absorption point R absorbs all the radio waves. That is, when a radio wave is transmitted from the transmission point T at the focal point of the parabolic surface of the wall portion 11 in the radio wave propagation room, all transmission is performed by the radio wave absorber at the reception absorption point R at the focal point of the parabolic surface of the wall portion 12. The received radio waves can be received and absorbed.

When the wireless base station device of the wireless LAN access point is provided at the transmission point T, the wireless terminal device for performing wireless communication with the wireless base station device is provided with the wall portion 11 and the wall portion 1.
It can be provided at any place between the two. Although FIG. 2 illustrates transmission from the wireless base station device and reception by the wireless terminal device, in the case of transmission from the wireless terminal device and reception by the wireless base station device,
The arrows in FIG. 2 are reversed.

Furthermore, when a radio wave is radiated from the transmission point T using the directional antenna, in the radio terminal device, the generation of multiple reflected waves is completely prevented, and the once-reflected wave on the wall portion 11 is completely prevented. It is possible to construct a stable wireless communication environment without any fading. When radiating the radio wave from the transmission point T, the directional antenna may not be used and the radio wave may be radiated using an omnidirectional antenna. In this case, the generation of multiple reflected waves cannot be completely prevented, but Part 1
1 and the wall portion 12, in the wireless terminal device, the direct wave from the transmission point T and the 1 in the wall portion 11 or 12
Fading occurs due to a composite wave of about two propagations with a reflected wave, but the fading magnitude is relatively small compared to the case of a room with a rectangular plane, and stable radio compared to the conventional example. You can build a communication environment.

According to the electromagnetic wave propagation room of the present embodiment, all the radio waves transmitted from the transmission point T are absorbed by the radio wave absorber provided at the reception absorption point R, which is explained in the section of the prior art. No multiple reflections occur. Therefore, interference waves such as multiple reflected waves do not occur, and stable wireless communication can be performed between the wireless base station device and the wireless terminal device. Further, since the radio wave absorber needs to be provided only at the reception absorption point R, the amount of use of the radio wave absorber can be significantly reduced and the manufacturing cost can be significantly reduced.

In the first embodiment described above, 13 is the ceiling portion and 14 is the floor portion, but the present invention is not limited to this, and 15 may be the ceiling portion and 16 may be the floor portion.
Further, although the walls 15 and 16 have a planar shape, the present invention is not limited to this and may have a parabolic surface.

<Second Embodiment> FIG. 3 shows a second embodiment of the present invention.
3 is a cross-sectional view showing a planar shape of the radio wave propagation room according to the embodiment of FIG. In FIG. 3, the electromagnetic wave propagation room according to the second embodiment has flat wall portions 23, 23 having flat-shaped side surfaces facing each other and reflecting wall portions 21, 22 facing each other.
Surrounded by and. Here, the reflection wall portion 21 divides the parabolic surface wall portion 11 according to the first embodiment into a plurality of parabolic cross-section wall portions 21a, and connects the plurality of parabolic cross-section wall portions 21a with, for example, a linear cross-sectional shape. On the other hand, the reflection wall portion 22 is formed by connecting the cross-section wall portions 21b, and the parabolic wall portion 12 according to the first embodiment is provided with a plurality of parabolic cross-section wall portions 2.
2a, and the plurality of parabolic cross-section wall portions 22a are connected by, for example, a connection cross-section wall portion 22b having a linear cross-sectional shape. Further, the plurality of parabolic cross-section wall portions 21a are arranged so as to have the focal point of the parabolic surface at the same position (positioned at a transmission point T described later), and the plurality of parabolic cross-section wall portions 22a are arranged in the parabola. It is arranged so as to have the focal point of the surface at the same position (located at the reception absorption point R described later). That is, the reflection walls 21 and 22 have a so-called Fresnel lens shape. Here, the connecting cross-section wall portion 2
Reference numerals 1b and 22b denote partial areas that do not reflect radio waves.

In the radio wave propagation room configured as described above, radio waves are transmitted from the transmitting point T located at the focal point of the parabolic surface of the parabolic section wall portion 21a, as shown in FIG. Radiation limited azimuth 2 that can be reflected by
At 8, when transmitting using, for example, a directional antenna so as not to radiate to the wall portions 22, 23, 24, the transmitted radio waves are reflected by the parabolic cross-section wall portion 21a, and then the wall portions 23, 2
4 propagates in a direction parallel to the longitudinal direction and reaches the reflection wall portion 22. Next, the transmitted radio wave is transmitted through the parabolic section wall 2
All the radio waves reflected by any of 2a are reflected at the reception absorption point R (however, the position of the transmission point T in the height direction is located at the focal point of the parabolic surface of the parabolic section wall portion 22a.
The position in the height direction of the reception absorption point R is matched. ) And all the radio waves are absorbed by the radio wave absorber provided at the reception absorption point R. That is, when a radio wave is transmitted from the transmission point T at the focal point of the parabolic surface of the parabolic section wall portion 21a in the radio wave propagation room, the parabolic section wall portion 22 is formed.
All the transmitted radio waves can be received and absorbed by the radio wave absorber at the reception absorption point R at the focus of the parabolic surface of a.

Further, since radio waves cannot be reflected by the connecting cross-section walls 21b and 22b, the dead zone 27 as shown in FIG.
Occurs. When the wireless base station device of the wireless LAN access point is provided at the transmission point T, the wireless terminal device that performs wireless communication with the wireless base station device is provided between the reflection wall portion 21 and the reflection wall portion 22 as described above. It can be provided at any place except the dead zone 27. In addition, in FIG.
The transmission from the wireless base station device is illustrated in the case of reception by the wireless terminal device, but in the case of transmission from the wireless terminal device and reception by the wireless base station device, the arrow in FIG. Become.

The electromagnetic wave propagation room according to this embodiment has the same effects as those of the first embodiment, and a plurality of parabolic cross-section wall portions 21a are used to form a pseudo parabolic surface. Since the pseudo parabolic surface is formed by using the parabolic cross-section wall portion 22a, the shape of the room can be approximated to a rectangular shape, so that the occupied space can be efficiently and effectively used. .

In the above second embodiment, the plane wall portions 23 and 24 are formed into a flat shape, but the reflection wall portion 21 and
It may be 22. Further, although the flat wall portions 23 and 24 are wall portions in the height direction, 23 may be a ceiling portion and 24 may be a floor portion.

<Third Embodiment> FIG. 6 is a perspective view showing the shape of a radio wave propagation room according to a third embodiment of the present invention, and FIG. 7 is a radio wave propagation state in the radio wave propagation room of FIG. It is sectional drawing about the XY plane of FIG. 6 which shows an example. The electromagnetic wave propagation room according to the third embodiment includes an elliptical cross-section wall portion 31 having an elliptical planar cross-sectional shape, and a ceiling portion 32 and a floor portion 33 that sandwich the elliptical cross-section wall portion 31 and face each other.

In the radio wave propagation room configured as described above, when a radio wave is transmitted from the transmission point T located at the first focus of the ellipse of the elliptical cross section wall portion 31 as shown in FIG. 7, it is transmitted. The radio waves, except for direct waves, have an elliptical section wall 3
After being reflected once by 1, all the reflected radio waves are received and absorbed at the reception absorption point R (however, the position in the height direction of the transmission point T is at the reception absorption point R) located at the second focal point of the ellipse of the elliptical section wall 31. All the radio waves are absorbed by the radio wave absorber provided at the reception absorption point R. Even if a radio wave is directly radiated from the transmission point T to the reception absorption point R, it can be received and absorbed at the reception absorption point R. That is, when a radio wave is transmitted from the transmission point T located at the elliptical first focal point of the elliptical cross-section wall portion 31 in the radio wave propagation room, the reception absorption point R located at the elliptical second focal point of the elliptical cross-section wall portion 31. The radio wave absorber can receive and absorb all transmitted radio waves.

When a wireless base station device for a wireless LAN access point is provided at the transmission point T, a wireless terminal device that wirelessly communicates with the wireless base station device is placed in a room surrounded by the elliptical section wall 31. Can be provided in any place. Note that, although FIG. 7 illustrates transmission from the wireless base station device and reception by the wireless terminal device, in the case of transmission from the wireless terminal device and reception by the wireless base station device, The arrows in FIG. 7 are reversed.

The electromagnetic wave propagation room according to this embodiment has the same effects as those of the first and second embodiments.
Although not shown in FIG. 7, a directional antenna that directionally radiates a beam from the transmission point T to the portion of the elliptical cross-section wall portion 31 as in the first embodiment (this directional antenna is It is preferable to have directivity that does not transmit a direct wave from the transmission point T to the wireless terminal device and the reception absorption point R. In this case, the radio wave from the transmission point T is reflected once from the transmission point T by the elliptical cross-section wall portion 31. Then, the wireless terminal device can completely prevent the generation of multiple reflected waves and construct a stable wireless communication environment without fading. . When an omnidirectional antenna is used, in the wireless terminal device provided in the room, a direct wave from the transmission point T,
Fading occurs due to a composite wave of about two propagations with the once-reflected wave at the elliptical cross-section wall portion 31, but the magnitude of fading is relatively small compared to the case of a room having a rectangular flat surface. A stable wireless communication environment can be constructed compared to the example.

<Fourth Embodiment> FIG. 8 is a sectional view showing a planar shape of a radio wave propagation room according to a fourth embodiment of the present invention, and FIG. 9 is a radio wave propagation in the radio wave propagation room of FIG. It is sectional drawing which shows an example of a state. In FIG. 8, the electromagnetic wave propagation room according to the fourth embodiment is surrounded by a reflection wall portion 41. Here, the reflection wall portion 41 divides the elliptical cross-section wall portion 31 according to the third embodiment into a plurality of elliptical cross-section wall portions 41a, and the plurality of elliptical cross-section wall portions 41a have, for example, a connecting cross section of a linear cross-sectional shape. It is connected by the wall portion 41b. A pseudo elliptical surface can be formed by the plurality of elliptical cross-section walls 41a, and the plurality of elliptical cross-section walls 41a have two common focal points (positioned at a transmission point T and a reception absorption point R described later). Arranged to have. The connecting cross-section wall portion 41b is a partial area that does not reflect radio waves.

In the radio wave propagation room configured as described above, radio waves are transmitted from the transmission point T located at the first focus of the ellipse of the elliptical cross section wall portion 41a, as shown in FIG. Radiation limited azimuth 48 that can be reflected by either
(Note that, in FIG. 9, that portion is shown by hatching.) When a radio wave is transmitted using, for example, a directional antenna so as not to be radiated by the connecting cross-section wall portion 41b, the transmitted radio wave has an elliptical cross-section wall portion 41a. After being once reflected by the ellipse, all the reflected electric waves are reflected by the second ellipse of the elliptical cross-section wall portion 41a.
Is provided at the reception absorption point R, which converges to the reception absorption point R located at the focal point of the point (however, the position of the transmission point T in the height direction is made to coincide with the position of the reception absorption point R in the height direction). The radio wave absorber absorbs all radio waves. Even if the radio wave is directly radiated from the transmission point T to the reception absorption point R, it can be received and absorbed. That is, when a radio wave is transmitted from the transmission point T at the first focus of the elliptical cross-section wall portion 41a in the radio wave propagation room, the radio wave absorber at the reception absorption point R at the second focus of the elliptical cross-section wall portion 41a. Allows all transmitted radio waves to be received and absorbed.

Further, since radio waves cannot be reflected by the connecting cross-section wall portion 41b, a dead zone may occur in the room. When the wireless base station device of the wireless LAN access point is provided at the transmission point T, the wireless terminal device that performs wireless communication with the wireless base station device can be provided at a predetermined place in the room. Note that, although FIG. 9 illustrates transmission from the wireless base station device and reception at the wireless terminal device, in the case of transmission from the wireless terminal device and reception at the wireless base station device, The arrows in FIG. 9 are reversed.

Further, when a radio wave is radiated from the transmission point T using the directional antenna, the wireless terminal device completely prevents the generation of multiple reflected waves, so that the elliptic cross-section wall portion 41a can be transmitted once. It is possible to construct a stable wireless communication environment in which only reflected waves arrive and fading does not occur. Note that when radiating radio waves from the transmission point T, radio waves may be radiated using an omnidirectional antenna instead of using the directional antenna,
In this case, although it is not possible to completely prevent the generation of multiple reflected waves, in the wireless terminal device provided in the room, the direct wave from the transmission point T and the one-time reflected wave at the elliptical cross-section wall portion 41a Fading occurs due to a composite wave of about two propagations with a reflected wave, but the fading magnitude is relatively small compared to the case of a room with a rectangular plane, and stable radio compared to the conventional example. You can build a communication environment.

The electromagnetic wave propagation room according to this embodiment has the same effects as those of the first to third embodiments, and also forms a pseudo elliptical surface by using a plurality of elliptical cross-section wall portions 41a. Since the shape of the room can be approximated to a rectangular shape, the occupied space can be used efficiently and effectively.

<Modification> In the above embodiments, the radio wave propagation room has been described, but the present invention is not limited to this, and may be applied to various spaces such as an anechoic chamber and other rooms. You can

In the above-described third and fourth embodiments, the wall portion 31 having an elliptical cross section is used for radio wave reflection, but the present invention is not limited to this, and the reflection wall portion has a spheroidal shape. You may comprise.

[0037]

As described in detail above, according to the radio wave propagation space of the first invention, at least two first and second parabolic sections or paraboloids each having one focal point are provided. A reflective surface and a radio wave absorber that is provided at the focal point of the second reflective surface when a radio wave is transmitted from the focus of the first reflective surface and that receives and absorbs the transmitted radio wave. According to the radio wave propagation space of the second invention,
At least one reflecting surface having an elliptical cross section or an ellipsoid of revolution surface having first and second focal points, and provided at a second focal point of the reflecting surface when a radio wave is transmitted from the first focal point of the reflecting surface. And a radio wave absorber that receives and absorbs the transmitted radio wave. Therefore, all the transmitted radio waves are absorbed by the radio wave absorber, and the multiple reflection described in the section of the related art hardly occurs. That is, an interference wave such as a multiple reflected wave does not occur, and stable wireless communication can be performed between the wireless base station device and the wireless terminal device. Further, since the radio wave absorber needs to be provided only at the reception absorption point R, the amount of use of the radio wave absorber can be significantly reduced and the manufacturing cost can be significantly reduced.

Further, since each of the reflecting surfaces has a plurality of reflecting surface portions connected to each other, the planar shape of the space can be approximated to a rectangle, and the installation space can be used efficiently and effectively. it can.

Furthermore, by further providing means for limiting the transmission angle so that the transmitted radio waves are reflected by the reflecting surface, all the transmitted radio waves are absorbed by the radio wave absorber, and no multiple reflection occurs. . That is, an interference wave such as a multiple reflected wave does not occur at all, and extremely stable wireless communication can be executed between the wireless base station device and the wireless terminal device.

[Brief description of drawings]

FIG. 1 is a perspective view showing a shape of a radio wave propagation room according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cross section on an XY plane of FIG.

FIG. 3 is a cross-sectional view showing a planar shape of a radio wave propagation room according to a second embodiment of the present invention.

4 is a cross-sectional view showing an example of a radio wave propagation state in the radio wave propagation room of FIG.

5 is a cross-sectional view showing a dead zone in the radio wave propagation room of FIG.

FIG. 6 is a perspective view showing the shape of a radio wave propagation room according to a third embodiment of the present invention.

7 is a sectional view taken along the XY plane of FIG. 6, showing an example of a radio wave propagation state in the radio wave propagation room of FIG.

FIG. 8 is a cross-sectional view showing a planar shape of a radio wave propagation room according to a fourth embodiment of the present invention.

9 is a sectional view showing an example of a radio wave propagation state in the radio wave propagation room of FIG.

[Explanation of symbols]

11, 12, 15, 16 ... Wall part, 13 ... Ceiling, 14 ... Floor, 18 ... Radiation limited azimuth angle, 21, 22 ... Reflective wall part, 21a, 22a ... Parabolic section wall part, 21b, 22b ... Connection cross-section wall portion, 23, 24 ... Plane wall portion, 27 ... dead zone, 28 ... Radiation limited azimuth angle, 31 ... Wall section of elliptical cross section, 32 ... the ceiling, 33 ... floor, 41 ... Wall for reflection, 41a ... Wall section of elliptical cross section, 41b ... Connection cross-section wall portion, 48 ... Radiation limited azimuth, T ... sending point, R: Reception absorption point.

Claims (7)

[Claims] 1. At least two first and second reflecting surfaces each having a parabolic cross section or a parabolic surface having one focus, and when the radio wave is transmitted from the focus of the first reflecting surface, the first A radio wave propagation space provided with a radio wave absorber that is provided at the focal point of the second reflection surface and that receives and absorbs the transmitted radio wave. 2. The radio wave propagation space according to claim 1, wherein each of the reflecting surfaces comprises a plurality of reflecting surface portions connected to each other. 3. When the radio wave is transmitted from the focal point of the first reflecting surface, a means for limiting a transmission angle is further provided so that the transmitted radio wave is reflected by the first reflecting surface. The radio wave propagation space according to claim 1 or 2. 4. At least one reflecting surface having an elliptical cross section or an ellipsoidal rotator surface having first and second focal points, and when the radio wave is transmitted from the first focal point of the reflecting surface, the first of the reflecting surfaces. A radio wave propagation space, which is provided at a focal point of 2 and has a radio wave absorber that receives and absorbs the transmitted radio wave. 5. The radio wave propagation space according to claim 4, wherein the reflecting surface has a plurality of reflecting surface portions connected to each other. 6. When the radio wave is transmitted from the first focal point of the reflecting surface, a means for limiting a transmission angle is further provided so that the transmitted radio wave is reflected by the reflecting surface. The radio wave propagation space according to claim 4. 7. The radio wave propagation space according to claim 1, wherein the space is a room or an anechoic chamber.