JP2020077988A - Antenna device - Google Patents

Abstract

To provide a technique for expanding a communicable angle range without increasing a scale of a high-frequency circuit for processing transmission and reception signals of an antenna.SOLUTION: A base 3 has one installation surface 3a formed in a planar shape. An antenna unit 6 is formed on the installation surface 3a and has a plurality of directional antennas configured to have a peak of directivity in a direction intersecting with the installation surface 3a. A reflection unit 4 has a plurality of reflecting surfaces for tilting directions indicated by peaks of the directional antennas to be oriented in mutually different directions in a plane at least along the installation surface 3a by reflecting electromagnetic waves transmitted and received by the antenna unit 6.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an antenna device.

  Wireless communication using millimeter waves and the like such as the fifth generation mobile communication system is known. Since a high-frequency signal such as a millimeter wave has a large transmission loss, it is necessary to provide a transmitting / receiving circuit or the like for processing the high-frequency signal transmitted / received by the antenna near the antenna. On the other hand, Patent Document 1 below describes a technique of integrating a part of a high frequency circuit with a substrate on which an antenna is formed.

JP, 2011-97526, A

However, as a result of detailed study by the inventor, the following problems were found.
A directional antenna such as a phased array antenna is used to realize communication in a practical distance range in millimeter waves and the like. The phased array antenna is formed by arranging a plurality of antenna elements on the same plane such as an antenna substrate.

  In addition, since radio waves such as millimeter waves have short wavelengths and have a strong straight-line characteristic, it is required that the transmission side and the reception side have a good line-of-sight relationship in order to establish communication. Here, considering communication between a mobile station mounted on a vehicle and a base station whose position is fixed, the positional relationship between the base station and the mobile station changes variously as the vehicle moves. Therefore, it is desirable that the mobile station design the antenna so that the mobile station can communicate with any direction in the entire angular range (that is, 360 °) in the horizontal plane.

  In other words, in communications using radio waves such as millimeter waves, multiple directional antennas are required to cover a wide range of angles in the horizontal plane, and each directional antenna is directed toward the area covered by it. In order to radiate radio waves, it was necessary to arrange them in different directions.

  Further, in this case, the plurality of antenna substrates on which the directional antennas are formed need to be arranged at spatially separated positions, for example, arranged so as to form each plane of a polygonal prism. That is, it is difficult to provide a common high-frequency circuit because the wiring between the antenna substrates becomes long, and it is necessary to provide a high-frequency circuit for each antenna substrate, resulting in an increase in the scale of the high-frequency circuit.

  One aspect of the present disclosure is to provide a technique for expanding a communicable angle range without increasing the scale of a high-frequency circuit that processes a transmission / reception signal of an antenna.

  One aspect of the present disclosure is an antenna device (1) that includes a base portion (3), an antenna portion (6), and a reflecting portion (4). The base has one installation surface (3a) formed in a flat shape. The antenna unit has a plurality of directional antennas formed on the installation surface and configured to have a directivity peak in a direction intersecting with the installation surface. The reflector has a plurality of reflectors that reflect the radio waves transmitted and received by the antenna. The plurality of reflectors inclines the directions indicated by the peaks of the plurality of directional antennas so as to face different directions at least in a plane along the installation surface.

  According to such a configuration, since the plurality of antenna substrates on which the directional antennas are mounted are arranged on the same plane as the installation surface, since the reflection section is provided, 360 in the horizontal plane along the installation surface is arranged. ° The entire angle range can be the communication range. Further, the directivity control of 360 degrees in the horizontal direction can be performed only by controlling the power feeding to the directional antennas arranged on the same plane.

  Since the plurality of antenna substrates are arranged on the same plane in a state of being close to each other with the reference point as the center, it is easy to provide a high-frequency circuit that commonly processes signals transmitted and received by the plurality of directional antennas. The circuit scale of the high frequency circuit can be reduced.

It is a perspective view which shows the structure of an antenna device. It is a top view of an antenna device shown in a state where a reflector is seen through. It is explanatory drawing which shows the effect | action of a reflector. It is a graph which shows the effect of the bump formed in the partition plate. It is explanatory drawing which shows the attachment state of the antenna device with respect to a vehicle.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. Constitution]
The antenna device 1 constitutes a part of a mobile station which is mounted on a vehicle and communicates with a base station using radio waves such as millimeter waves. The antenna device 1 is arranged, for example, outside the ceiling of the vehicle 100, as shown in FIG. The millimeter wave and the like include not only the so-called millimeter wave band of 30 GHz to 300 GHz but also the frequency band around the millimeter wave band such as GHz or higher. More specifically, it may be any radio wave having a property of being reflected by a reflection plate 41 described later like a mirror surface.

  As shown in FIG. 1, the antenna device 1 includes a frame body 2, a base portion 3, a reflecting portion 4, a shielding portion 5, an antenna portion 6, and a cover portion 7. 5 shows a state in which the cover portion 7 is attached, and FIG. 1 shows a state in which the cover portion 7 is removed.

  The frame body 2 has a structure in which each side of a hexahedron is formed by a rod-shaped member. Of the six faces of the hexahedron, two opposite faces of the frame body 2 are formed in a square shape. In the following, of the portions forming the square in the frame body 2, one is referred to as an upper frame 2a and the other is referred to as a lower frame 2b. That is, each of the upper frame 2a and the lower frame 2b is formed of four rod-shaped members. Further, the four rod-shaped members connecting the upper frame 2a and the lower frame 2b are referred to as a vertical frame 2c. The frame body 2 may be a material that is lightweight and has the required strength, and may be resin or metal.

  The base portion 3 is composed of a square plate-shaped member, and the lower frame 2b of the frame body 2 is fixed to one plate surface (hereinafter, installation surface) 3a. Further, the base portion 3 is formed to be larger than the lower frame 2b, and four support plates 31 formed in the shape of a right triangle supporting the four vertical frames 2c from the outside of the frame body 2 at the four corners thereof. Are provided respectively. The base 3 has only to have a function of blocking radio waves, and is made of, for example, a metal material.

  The reflection part 4 has four points each having a triangular shape with a point on the installation surface 3a located at the center of the lower frame 2b as a reference point P, the reference point P as an apex, and each side of the upper frame 2a as a base. It has a structure in which plate-like members (hereinafter, reflecting plates) 41 are combined. That is, the reflecting portion 4 is formed in a quadrangular pyramid shape with the bottom surface being the bottom surface and the bottom surface being the bottom surface. The reflector 41 is made of a highly conductive metal material. The reflector 41 has an inclination of, for example, about 45 ° to 50 ° with respect to the base 3, and directs radio waves coming from the base 3, that is, from directly below, in the horizontal direction or slightly above the horizontal. Is set to reflect. That is, the frame body 2 is formed in a size capable of holding the reflection plate 41 at such an inclination angle. The surface of the reflection plate 41 facing the base 3 is a reflection surface.

  The shielding part 5 is composed of four plate-shaped members (hereinafter, partition plates) 51 which are formed in a triangular shape with the reference point P as the apex and each of the four vertical frames 2c as the base. The partition plate 51 is fixed in a state of being in close contact with the base portion 3 and the reflection plate 41. The partition plate 51 is formed of a conductive metal material. However, the partition plate 51 may have a lower conductivity than the reflection plate 41. Further, the partition plate 51 is provided with a large number of bumps 51a for forming irregularities on the surface thereof. The bumps 51a are provided between the contact side of the partition plate 51 with the base portion 3 and the height of about half the height from the upper frame 2a to the lower frame 2b. The bumps 51a are formed, for example, by subjecting the partition plate 51 to processing such as pressing and pressing.

  By the base 3, the reflection part 4, and the shielding part 5 configured in this way, four shielding spaces, which are electrically separated quadrangular pyramidal spaces, are formed inside the frame body 2. The part of the base 3 that forms each shielded space corresponds to a divided area in which the area on the installation surface 3a is divided into a plurality of areas with the reference point P as the center. That is, the base portion 3, the reflection portion 4, and the shield portion 5 form a shield structure that suppresses leakage of radio waves between the divided areas, and thus between the shield spaces.

  As shown in FIG. 2, the antenna unit 6 has four antenna substrates 61 arranged on the base 3 in each of the four shielded spaces. Note that FIG. 2 is a plan view of the antenna device 1 with the reflecting portion 4 seen through. The four antenna substrates 61 have the same structure. The antenna substrate 61 has a plurality of antenna elements 611 arranged two-dimensionally and a feeding line 612 that feeds power to each antenna element 611, and forms a phased array antenna. The feeding point S of the phased array antenna is provided at the center of each antenna board 61. Power is supplied to the feeding point S from the high frequency circuit through the back side of the antenna substrate 61 or the inner layer wiring. From the feeding point S, branch feeding to each antenna element 611 is performed via the feeding line 612.

  However, the antenna formed on the antenna substrate 61 is not limited to the phased array antenna, and may be a directional antenna having a peak in the direction normal to the pattern forming surface and thus the installation surface 3a. Here, the pattern forming surface refers to the surface of the antenna substrate 61 on the side where the antenna element 611 and the feeder line 612 are formed. Therefore, the antenna substrate 61 is arranged so that the surface on the side opposite to the pattern formation surface is in contact with the base 3. The peak of the directivity of the directional antenna formed on the antenna substrate 61 is directed toward the center of the angular range in which the divided area of the installation surface 3a exists from the reference point P by the reflection plate 51 (that is, the reflection surface). Will be tilted.

  The cover portion 7 is formed of a material that transmits radio waves such as millimeter waves and has a shape that covers five surfaces of the frame body 2 other than the contact surface with the base portion 3, and is fixed to the frame body 2 and the base portion 3. . That is, the cover part 7 forms a housing of the antenna device 1 together with the base part 3.

[2. motion]
The beam B representing the directivity of the single phased array antenna formed on the antenna substrate 61 has a peak directly above the pattern formation surface, as shown in the column of the single antenna in FIG. On the other hand, the beam B representing the directivity of the radiation wave from the antenna device 1 having the reflection plate 41 has a peak in the direction along the pattern forming surface, as shown in the column with reflection plate in FIG. Will have. This is because a radio wave having a high frequency such as a millimeter wave has a property similar to that of light and is reflected by the metal reflection plate 41 like a mirror.

  Further, the partition plate 51 is provided with irregularities formed by a large number of bumps 51a on its surface. The bumps 51a relatively increase the resistance of the path through which the eddy current flows by partially lengthening the distance of the current flowing on the surface of the partition plate 51. That is, the bumps suppress the generation of an eddy current, which is a generation source of a reflected wave, on the surface of the partition plate 51 due to the electric wave leaking from the antenna substrate 61 as a side lobe and entering the partition plate 51. As a result, in the antenna device 1, the reflection of the radio wave on the partition plate 51 is suppressed, and the disturbance of the directivity due to the reflected wave from the partition plate 51 is suppressed.

  FIG. 4 shows the results of measuring the directivity in the horizontal plane along the pattern formation surface with and without the bump 51a for the phased array antenna formed on each antenna substrate 61. Here, 27 GHz was used. The two-dot chain line in FIG. 4 is the directivity before being reflected by the reflector 41, and the thick solid line in FIG. 4 is the direction of the radio wave emitted from the antenna device 1 after being reflected by the reflector 41. It is sex. It can be seen that the spread of the beam after reflection is more suppressed in the case with bumps than in the case without bumps.

[3. effect]
According to the embodiment described in detail above, the following effects are obtained.
(3a) Since the antenna device 1 has the reflection portion 4, the plurality of antenna substrates 61 on which the directional antennas are mounted are arranged on the same plane as the installation surface 3a, but the entire 360 ° in the horizontal plane. The angle range can be the communication range. Further, the directivity control in the horizontal direction of 360 ° can be realized only by controlling the power feeding to the antenna substrate 61 (that is, the directional antenna) arranged on the same plane.

  (3b) Since the plurality of antenna substrates 61 are arranged on the same plane with the feeding points S of the respective antennas being close to each other with the reference point P as the center, signals transmitted and received by the plurality of directional antennas are transmitted. It is easy to provide a high-frequency circuit for common processing, and the circuit scale of the high-frequency circuit can be reduced.

[4. Other Embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be implemented.

  (4a) In the above embodiment, the partition plate 51 has the bumps 51a formed on the surface of the partition plate 51 as a reflection suppressing structure for suppressing the reflection of radio waves. However, the present disclosure is not limited to this. For example, a radio wave absorber may be provided on the surface of the partition plate 51 as a reflection suppressing structure. The electromagnetic wave absorber may be attached in the form of a sheet or may be applied in the form of a liquid. Further, the partition plate 51 may be configured by using a material having a low conductivity, instead of providing the reflection suppressing structure such as the bumps 51a or with the reflection suppressing structure.

  (4b) In the above embodiment, the four antenna substrates 61 are configured to cover 360 ° in the horizontal plane, but the number of the antenna substrates 61 is two or three, but five or more. You may.

  (4c) A plurality of functions of one constituent element in the above-described embodiment may be realized by a plurality of constituent elements, or one function of one constituent element may be realized by a plurality of constituent elements. . Further, a plurality of functions of a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above-described embodiment may be added or replaced with respect to the configuration of the other above-described embodiment.

  (4d) In addition to the above-described antenna device, the present disclosure can be realized in various forms such as a system having the antenna device as a constituent element.

  DESCRIPTION OF SYMBOLS 1 ... Antenna device, 2 ... Frame body, 2a ... Top frame, 2b ... Bottom frame, 2c ... Vertical frame, 3 ... Base part, 3a ... Installation surface, 4 ... Reflection part, 5 ... Shield part, 6 ... Antenna part, 31 ... Support plate, 41 ... Reflector, 51 ... Partition plate, 51a ... Bump, 61 ... Antenna substrate, 611 ... Antenna element, 612 ... Feed line, S ... Feed point, P ... Reference point.

Claims (10)

A base (3) having one installation surface (3a) formed in a planar shape,
An antenna part (6) having a plurality of directional antennas formed on the installation surface and having a directivity peak in a direction intersecting with the installation surface;
By reflecting the radio waves transmitted and received by the antenna section, a plurality of directions in which the peaks of the plurality of directional antennas are inclined are oriented so that they respectively face different directions at least in a plane along the installation surface. A reflection portion (4) having a reflection surface,
An antenna device including. The antenna device according to claim 1, wherein
The plurality of directional antennas, with a reference point set on the installation surface as the center, are arranged in each of divided areas obtained by dividing the area on the installation surface into a plurality of areas.
The reflection part is arranged in the divided area, and the reflection surface is arranged so as to incline a directivity peak in the directional antenna toward the center of an angular range in which the divided area exists from the reference point. ,
Antenna device. The antenna device according to claim 2, wherein
A shield part (5) having a plurality of partition plates (51) forming a shield structure for suppressing the leakage of radio waves between the plurality of divided areas together with the reflector,
Antenna device. The antenna device according to claim 3, wherein
The partition plate has an antireflection structure for suppressing the reflection of radio waves, The antenna device according to claim 4, wherein
The antenna device, wherein the reflection suppressing structure is a plurality of bumps (51a) formed on a surface of the partition plate. The antenna device according to claim 4, wherein
The antenna device, wherein the reflection suppressing structure is a radio wave absorber provided on a surface of the partition plate. The antenna device according to any one of claims 1 to 6, wherein:
The directional antenna is a phased array antenna,
Antenna device. The antenna device according to any one of claims 1 to 7, wherein:
An antenna device, which is formed of a material that transmits radio waves transmitted and received by the antenna unit, and further includes a cover unit that forms a housing of the antenna device together with the base unit. The antenna device according to any one of claims 1 to 8, wherein:
The number of the directional antennas and the number of the reflectors are set so that the directivities of the plurality of directional antennas reflected by the reflector cover an angle range of 360 ° on a plane along the installation surface. An antenna device with a reflective surface. The antenna device according to any one of claims 1 to 9, wherein:
The directional antenna configuring the antenna unit is configured to transmit and receive radio waves in the millimeter wave band,
Antenna device.

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