Reflector array, reflector array system, communication system, wall material with built-in reflector array, and mobile communication system

Abstract

To provide a reflection array capable of simplifying installation of the reflection array by enabling reflection with a plurality of incident angles without causing reduction in electric field intensity of a reflector while keeping high gain.SOLUTION: A reflection array comprises a plurality of first elements and a plurality of second elements disposed on an XY plane. The first elements are arranged in the Y direction to form first element rows. The second elements are arranged in the Y direction to form second element rows. The first element rows and the second element rows line up alternately in the X direction. Two angles causing maximum incidence / reflection are on the same positive or negative side of the X axis.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a reflectarray, a reflectarray system using the reflectarray, a communication system, a wall material incorporating a reflectarray, and a mobile communication system.

Background Art

[0002] In a mobile communication system, signals are transmitted and received by radio waves between a base station and a communication terminal. Since the number of base stations is limited, an area where radio waves from the base station do not easily reach directly occurs. To solve this, a reflectarray may be used. Conventional reflectarray reflectors can arbitrarily design the incident angle and the reflection angle. Patent Document 1 describes a metasurface reflector and a traffic signal including the metasurface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the incident angle and the reflection angle of the reflectarray reflector are respectively defined and designed in one direction, good reflection is shown for both the forward incidence of the designed angle shown in FIG. 1 and the reverse incidence shown in FIG. 2, and the electric field strength of the reflected wave becomes strong. However, the installation position and angle of the reflector depend on the position of the base station device and are uniquely determined. As in the case of FIG. 3, it often does not operate normally for incident waves other than the designed angle. Since the reflector needs to be installed facing the base station direction, it becomes a major constraint during installation. As shown in FIGS. 4, 5, and 6, when the incident wave or the reflected wave is designed to have a plurality of angular directions, the restrictions on the installation position, angle, etc. are relaxed, but the electric field strength in the desired direction decreases. For example, for both the forward incidence shown in FIG. 4 and the reverse incidence shown in FIGS. 5 and 6, reflection occurs in directions other than the target communication terminal or base station, so the gain decreases compared to the case of reflecting in a single direction. Thus, when a high electric field strength of the reflected wave is required, in a configuration where the reflected wave is concentrated in one direction for one incident direction, it is necessary to accurately align the installation position and direction of the reflector with the direction of the base station. If the position of the base station device is not determined in advance, it is difficult to install the reflector. Also, in a configuration where the incident wave or the reflected wave is designed in advance to have a plurality of angular directions, the electric field strength of the reflected wave decreases. Therefore, an object of the present invention is to provide a reflector array that can reflect at a plurality of incident angles or reflection angles without causing a decrease in the electric field strength of the reflector while maintaining a high gain, and can simplify the installation of the reflector array. Another object of the present invention is to provide a reflector array that can realize a plurality of incident and reflection angles without reducing the directivity gain. Furthermore, an object of the present invention is to provide a reflector array that simplifies the installation of the reflector array (metamaterial reflector).

Means for Solving the Problems

[0005] The reflector array according to claim 1 of the present invention is Taking three mutually orthogonal directions as the X direction, Y direction, and Z direction, A plurality of first elements and second elements are respectively arranged on the XY plane, The first elements are arranged in the Y direction to form a first element row, The second elements are arranged in the Y direction to form a second element row, the first element row and the second element row are arranged alternately, a reflectarray, characterized in that two angles that cause maximum incident reflection are on the same positive or negative side of the X axis. The reflectarray according to claim 2 of the present invention is the reflectarray according to claim 1, characterized in that two angles that cause maximum incident reflection are, with respect to the Z axis, one is from 1 degree to 30 degrees and the other is from 60 degrees to 89 degrees. The reflectarray according to claim 3 of the present invention is the reflectarray according to any one of claims 1 or 2, characterized in that it is a deformable sheet. The reflectarray according to claim 4 of the present invention is the reflectarray according to any one of claims 1 to 3, characterized in that it has a fixing part for fixing the reflectarray to the outside. The reflectarray system according to claim 5 of the present invention is comprising a plurality of reflectarrays according to any one of claims 1 to 4, taking the line of intersection of the plane including two directions that cause maximum incident reflection and the XY plane as the incident reflection direction, a reflectarray system, characterized in that reflectarrays with different incident reflection directions are arranged alternately. The reflectarray system according to claim 6 of the present invention is comprising a plurality of reflectarrays according to any one of claims 1 to 4, taking the line of intersection of the plane including two directions that cause maximum incident reflection and the XY plane as the incident reflection direction, a reflectarray system, characterized in that reflectarrays with incident reflection directions different by 90 degrees from each other are arranged alternately. The reflectarray system according to claim 7 of the present invention is Having a plurality of the reflect arrays according to any one of claims 1 to 4, Taking the line of intersection between the plane including the two directions that produce the maximum incident reflection and the XY plane as the incident reflection direction, A plurality of reflect arrays are arranged such that the incident reflection directions are different from each other by substantially a predetermined angle, A reflect array system, characterized in that the incident reflection direction is configured to change substantially in a curved shape. The communication system according to claim 8 of the present invention, Having a plurality of base stations and the reflect array according to any one of claims 1 to 4, A communication system, characterized in that a reflect array is installed between two of the plurality of base stations. The communication system according to claim 9 of the present invention, The base station is arranged on a wall surface, A communication system, characterized in that the reflect array according to any one of claims 1 to 4 or the reflect array system according to any one of claims 5 to 7 is provided on a ceiling. The communication system according to claim 10 of the present invention, Having a base station, A communication system, characterized in that the reflect array according to any one of claims 1 to 4 or the reflect array system according to any one of claims 5 to 7 is provided on a wall surface. The communication system according to claim 11 of the present invention, Having a base station, A communication system, characterized in that the reflect array according to any one of claims 1 to 4 or the reflect array system according to any one of claims 5 to 7 is provided on a floor. The wall material with a built-in reflect array according to claim 12 of the present invention, A base material, and A reflective array according to any one of claims 1 to 4, or a reflective array system according to any one of claims 5 to 7, characterized by having a wall material with a built-in reflective array. The mobile communication system according to claim 13 of the present invention has a mobile receiver, and is a mobile communication system characterized by having, inside the mobile body, a reflective array according to any one of claims 1 to 4, or a reflective array system according to any one of claims 5 to 7. With this configuration, the periodic structure of the reflective array becomes substantially left-right symmetric, and two independent types of incident and reflection angles can be realized. Normally, in order to realize two types of incident and reflection angles, beam splitting into two beams was necessary, but when beam splitting into two beams occurred, a decrease in gain occurred. However, according to this configuration, since the two types of incident and reflection angles operate independently, a high gain can be maintained. Also, although the reflective array is often installed outside, conventionally, due to its low designability, it was often installed so as to be hidden in an inconspicuous place, and the installation location was greatly restricted. In this configuration, since it is a repetition of a periodic column, it has high designability, and it can be installed as it is even in places that catch people's eyes, such as ceilings, wall surfaces, and floors.

Brief Description of the Drawings

[0006]

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Mode for Carrying Out the Invention

[0007] FIG. 7, FIG. 8, and FIG. 9 show a configuration example of a reflectarray in an embodiment of the present invention. As shown in FIGS. 8 and 9, three mutually orthogonal directions are defined as the X direction, the Y direction, and the Z direction. The X-axis, Y-axis, and Z-axis are the axes in the X direction, Y direction, and Z direction, respectively.

[0008] As shown in FIG. 7, in the reflectarray 100, a plurality of first elements 111 and second elements 121 are respectively arranged on the XY plane. The first elements 111 are arranged in the Y direction to form a first element row 110, and the second elements are arranged in the Y direction to form a second element row 120. The first element row 110 and the second element row 120 are alternately arranged in the X direction. And it serves as a metamaterial reflector.

[0009] As shown in FIG. 8, the design incident angle and the design reflection angle, which are two angles that cause the maximum in-reflection, are on the same positive or negative side of the X-axis. Hereinafter, the "incident angle" may mean the incident direction in addition to the incident angle. Similarly, hereinafter, the "reflection angle" may mean the reflection direction in addition to the reflection angle. The same applies to the "design incident angle", "design reflection angle", etc.

[0010] In this embodiment, the designed incident angle is inclined by θi from the vertical direction, i.e., the Z direction, to the negative direction of the horizontal direction, i.e., the X direction. Also, the designed reflection angle is in the negative direction of the X direction and is inclined by θr from the vertical direction, i.e., the Z direction. Then, the first element row 110 and the second element row 120 are arranged alternately in the X direction, so that a symmetric structure is formed in the X direction, i.e., left and right. And when a plurality of them are arranged in the horizontal direction, even when the designed incident angle is inclined by θi from the vertical direction, i.e., the Z direction, to the positive direction of the horizontal direction, i.e., the X direction, and the designed reflection angle is in the positive direction of the X direction and is inclined by θr from the vertical direction, i.e., the Z direction, the same operation can be realized.

[0011] As shown in FIG. 9, in this embodiment, a reflectarray 100 is configured by arranging a plurality of supercells 131, each of which arranges a first element 111 and a second element 121 one by one in the X direction, in the X-axis direction and the Y-axis direction. Note that the X direction and the Y direction are approximate directions and may be bent, for example, by about 10 degrees. With this configuration, a plurality of incident and reflection angles can be realized without reducing the directivity gain.

[0012] FIGS. 10 and 11 show the intensity of incident and reflection in the above example. Also, FIG. 12 shows the reflection by the incident wave from the forward direction. FIG. 13 shows the reflection by the incident wave from the reverse direction, which is opposite to the forward direction. FIG. 14 shows the reflection by the incident wave from the opposite side of the designed angle. In FIG. 10, the results at three frequencies D1, D2, and D3 are shown. D1 = 0.93×D2 and D3 = 1.07×D2. In this embodiment, the incident angle is designed to be -10 degrees. The solid line shows the result of incidence at -10 degrees, and the dashed line shows the result of incidence at +10 degrees. As shown in FIG. 11, good reflection is shown for both excitations in the forward and reverse directions. Also, as shown by the dashed line in FIG. 11, it operates similarly for the incident wave from the opposite side of the designed angle and shows good reflection.

[0013] In one embodiment, it is desirable that, with respect to the Z-axis, two angles that produce maximum incident reflection are, on the one hand, from 1 degree to 30 degrees and, on the other hand, from 60 degrees to 89 degrees. In the metamaterial reflector in which the first element row 110 and the second element row 120 are arranged alternately, with these angles, it becomes easy to transmit and receive radio waves with sufficient intensity required for communication.

[0014] In one embodiment, it is more desirable that, with respect to the Z-axis, two angles that produce maximum incident reflection are, on the one hand, from 5 degrees to 20 degrees and, on the other hand, from 70 degrees to 85 degrees. In the metamaterial reflector in which the first element row 110 and the second element row 120 are arranged alternately, with these angles, the incident radio waves can be further concentrated, and it becomes even easier to transmit and receive radio waves with sufficient intensity required for communication.

[0015] In one embodiment, the reflectarray 100 can be in the form of a deformable sheet. With this configuration, although the incident reflection of radio waves for communication is somewhat different from the previous case, it can also cope with cases where the installation location is deviated from a plane, such as when the surface has curvature.

[0016] FIG. 15 shows a configuration example of a reflectarray system 200 according to an embodiment of the present invention. The reflectarray 100 has a fixing portion 190 for fixing the reflectarray 100 to an external object such as another member or another substantially flat portion. In this embodiment, four fixing portions 190 are arranged at the four corners of the reflectarray. The fixing portion 190 may be an adhesive portion. Alternatively, it may be a fitting. Also, screws or the like may be used. According to this configuration, the reflectarray 100 can be easily installed on existing members such as indoor wall surfaces, ceilings, windows, and doors.

[0017] FIG. 16, FIG. 17, FIG. 18, FIG. 19, and FIG. 20 show configuration examples of a reflectarray system 200 according to an embodiment of the present invention. In this embodiment, the reflect array system 200 has a plurality of the above-described reflect arrays 100.

[0018] The line of intersection between the plane including the two directions that cause the maximum in-reflection and the XY plane is defined as the in-reflection direction. Reflect arrays 101 and 102 with different in-reflection directions are alternately arranged. In FIG. 18, reflect arrays 101 and 102 with in-reflection directions different from each other by 90 degrees are alternately arranged. Of course, reflect arrays different from each other by 45 degrees may be alternately arranged, or other angles such as 60 degrees may be used.

[0019] Although there are two directions in which one type of reflect array can be used, in this embodiment, it is rotated by 90 degrees to form a checkerboard pattern array that covers four directions. With this configuration, the directivity is relaxed, and it becomes possible to embed the above-described reflector in the ceiling material in advance.

[0020] FIG. 19 shows a configuration example of the reflect array system 200 in an embodiment of the present invention. In this embodiment, three types of reflect arrays 101, 104, and 105 with in-reflection directions different from each other by 60 degrees are periodically arranged. Note that "alternately arranged" includes a configuration that is periodically arranged in this way. In this embodiment, reflect array 101 has an in-reflection direction in the X-axis direction, reflect array 104 has an in-reflection direction in a direction inclined by +60 degrees in the XY plane from the X-axis direction, and reflect array 105 has an in-reflection direction in a direction inclined by -60 degrees in the XY plane from the X-axis direction.

[0021] FIG. 20 shows a configuration example of the reflect array system 200 in an embodiment of the present invention. In this embodiment, the reflect array system 200 has a plurality of the above-described reflect arrays 100.

[0022] The line of intersection between the plane containing the two directions that produce the maximum incident reflection and the XY plane is taken as the incident reflection direction. A plurality of reflect arrays 101, 102, 106, and 107 are arranged such that the incident reflection directions are different from each other by approximately a predetermined angle, and are configured such that the incident reflection directions change in a substantially curved shape. In this embodiment, as shown by the arrows in the figure, within the XY plane, the incident reflection directions rotate by 45 degrees in the order of reflect arrays 101, 106, 102, and 107. For example, when transmitting communication radio waves in a range that can view 360 degrees around in a stadium, there are many restrictions on the installation location, and adjustments are also required during installation for the base station 410, making installation difficult. However, with this configuration, it becomes possible to easily install with almost no restrictions on the installation location, and furthermore, it becomes possible to easily transmit communication radio waves over a wide range such as 360 degrees around.

[0023] FIG. 21 and FIG. 22 show a configuration example of a communication system 400 in an embodiment of the present invention. In this embodiment, the communication system 400 has a plurality of base stations and the above-described reflect array 100. And, among the plurality of base stations, a reflect array 100 is installed between two base stations 411 and 412.

[0024] With this configuration, on the opposite side of the designed incident angle in the negative direction in the X direction, that is, it is also possible to have incident reflection in the positive direction in the X direction, and positive and negative reverse incidence can be effectively utilized. Note that the installation location of the base station is often restricted. Therefore, even when there is only one base station, according to the reflect array 100 in the present invention, the communication system 400 can operate regardless of whether the base station 410 is installed at the position of the base station 411 or the position of the base station 412. This makes it possible to install the reflect array system (reflector) 200 even before the position of the base station 410 is determined. Also, even if the position of the base station 410 is changed after the installation of the reflect array system (reflector) 200, it is possible to respond without the need to install the reflect array system (reflector) 200 again.

[0025] FIG. 23 shows a configuration example of the communication system 400 in an embodiment of the present invention. In this embodiment, in the communication system 400, the base station 410 is arranged on the wall surface 702, and the above-described reflect array 100 or the above-described reflect array system 200 is provided on the ceiling 701. Regarding the base station 410, as long as the communication radio wave is transmitted from the direction of the wall surface 702, the support location of the base station 410 is not limited, such as suspending the base station 410 from the ceiling 701. Such a configuration is also included in the configuration of "the base station is arranged on the wall surface".

[0026] When the base station 410 is installed on the wall surface 702, a dead zone is likely to be formed due to blocking by people, machines, furniture, etc. In this configuration, the reflect array (reflector) 100 is installed on the ceiling 701, and the radio wave is reflected toward the dead zone from above.

[0027] At the installation location, there may be cases where it is difficult to install the reflect array 100 or the reflect array system 200 on the ceiling 701, or where the ceiling 701 is too high and not suitable for installation. The reflect array 100 and the reflect array system 200 in the present invention can be configured to be provided on the wall surface 702 or the floor 703 in addition to the ceiling 701, as long as the installation location can easily ensure the line of sight between the reflect array (reflector) 100 and the terminal and is less affected by blocking.

[0028] FIG. 24 shows a configuration example of the communication system 400 in an embodiment of the present invention. In this embodiment, the above-described reflect array 100 or the above-described reflect array system 200 is provided on the wall surface 702.

[0029] FIG. 25 shows a configuration example of a communication system 400 according to an embodiment of the present invention. In this embodiment, the above-described reflect array 100 or the above-described reflect array system 200 is provided on the floor 703.

[0030] FIGS. 26 and 27 show a configuration example of a wall material 300 with a built-in reflect array according to an embodiment of the present invention. Note that FIG. 27 is an exploded view. In this embodiment, the wall material 300 with a built-in reflect array has a base material 310 and the above-described reflect array or the above-described reflect array system 200. In this configuration, a reflect array is formed on the base material 310, but it is also possible to integrally form the reflect array or the reflect array system 200 and the base material 310.

[0031] FIG. 28 shows a configuration example of a mobile communication system 500 according to an embodiment of the present invention. In this embodiment, the mobile communication system 500 has a mobile receiver 520 and has the above-described reflect array 100 or the above-described reflect array system 200 inside the mobile body 510.

[0032] In a mobile body 510 that moves at high speed, such as a vehicle or an aircraft, the distance to the base station 410 is often long. For this reason, the angle of sighting the base station 410 from the mobile receiver 520 may become small. According to this configuration, since the reflect array 100 reflects radio waves for communication inside the mobile body, it is possible to surely receive the radio waves for communication from the base station 410.

[0033] Needless to say, the present invention is not limited to the above embodiments and includes various embodiments without departing from the spirit of the present invention.

Description of Symbols

[0034] 100 - 107 Reflector Array 110 First Element Array 120 Second Element Array 111 First Element 121 Second Element 131 Supercell 190 Fixed Part 200 Reflector Array System 300 Wall Material with Built - in Reflector Array 310 Base Material 400 Communication System 410, 411, 412 Base Stations 500 Mobile Communication System 510 Mobile Body 520 Mobile Body Receiver 6 Communication Terminal 700 Building 701 Ceiling 702 Wall 703 Floor

Claims

1. Taking three mutually perpendicular directions as the X direction, Y direction, and Z direction, A plurality of first elements and second elements are respectively arranged on the XY plane, The first elements are arranged in the Y direction to form a first element row, The second elements are arranged in the Y direction to form a second element row, The first element row and the second element row are arranged alternately, Two angles that cause the maximum incident reflection are on the same positive or negative side of the X axis, A reflectarray, characterized in that, of the two angles that cause the maximum incident reflection, one is from 1 degree to 30 degrees and the other is from 60 degrees to 89 degrees with respect to the Z axis.

2. The reflectarray according to claim 1, characterized in that it is a deformable sheet.

3. The reflectarray according to claim 1 or 2, characterized in that it has a fixing part for fixing the reflectarray to the outside.

4. Having a plurality of the reflectarrays according to any one of claims 1 to 3, Taking the line of intersection between the plane including the two directions that cause the maximum incident reflection and the XY plane as the incident reflection direction, A reflectarray system, characterized in that the reflectarrays with different incident reflection directions are arranged alternately.

5. Having a plurality of the reflectarrays according to any one of claims 1 to 3, Taking the line of intersection between the plane including the two directions that cause the maximum incident reflection and the XY plane as the incident reflection direction, A reflectarray system, characterized in that the reflectarrays with incident reflection directions different from each other by 90 degrees are arranged alternately.

6. Having a plurality of the reflectarrays according to any one of claims 1 to 3, Taking the line of intersection between the plane including the two directions that cause the maximum incident reflection and the XY plane as the incident reflection direction, A plurality of the reflectarrays with incident reflection directions different from each other by approximately a predetermined angle are arranged, A reflectarray system, characterized in that the incident reflection directions are configured to change in a substantially curved shape.

7. Having a plurality of base stations and the reflectarray according to any one of claims 1 to 3, A communication system, characterized in that the reflectarray is installed between two of the plurality of base stations.

8. The base station is arranged on a wall surface. A communication system, characterized in that the reflect array according to any one of claims 1 to 3 or the reflect array system according to any one of claims 4 to 6 is provided on the ceiling.

9. Having a base station, A communication system, characterized in that the reflect array according to any one of claims 1 to 3 or the reflect array system according to any one of claims 4 to 6 is provided on the wall surface.

10. Having a base station, A communication system, characterized in that the reflect array according to any one of claims 1 to 3 or the reflect array system according to any one of claims 4 to 6 is provided on the floor.

11. A base material, and Characterized by having the reflect array according to any one of claims 1 to 3 or the reflect array system according to any one of claims 4 to 6 Wall material with built-in reflect array.

12. Having a mobile receiver, A mobile communication system, characterized in that the reflect array according to any one of claims 1 to 3 or the reflect array system according to any one of claims 4 to 6 is provided inside the mobile body.

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