Antenna device

Abstract

To provide an antenna device capable of securing isolation for preventing wraparound of radio waves while obtaining gain of the radio waves.SOLUTION: An antenna device 10 includes a substrate 300, a transmission antenna 100 provided on the substrate 300, and a reception antenna 200 provided on the same plane as a substrate plane of the substrate 300 where the transmission antenna 100 is provided. The antenna device 10 includes a first dielectric lens 110 having a convex shape formed in a first direction, which is perpendicular to the substrate plane of the substrate 300, and a second direction, which is opposite to the first direction, at a position a predetermined length away from the transmission antenna 100 in the first direction. In addition, the antenna device 10 includes a second dielectric lens 210 having a convex shape formed in the first direction and the second direction at a position a predetermined length away from the reception antenna 200 in the first direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an antenna device. [Background technology]

[0002] Conventionally, in the fifth generation wireless communication, the TDD (Time Division Duplex) method is used, which transmits and receives on the same frequency at different times. Therefore, in the case of RoF (Radio over Fiber), which is capable of full-duplex communication that relays and transmits wireless signals, the transmitted radio waves are leaked to the receiving circuit side, and the leaked radio waves are relayed and looped, causing oscillation. In order to suppress the leakage of radio waves, a technology has been proposed that ensures radio wave isolation and prevents leakage from the transmitting antenna to the receiving antenna. Patent Document 1 discloses a wireless communication device that suppresses interference between antenna elements. The wireless communication device disclosed in Patent Document 1 includes a lens that narrows the width of a directional beam emitted from an antenna in a predetermined direction, and suppresses interference between antenna elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-201081 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, radio waves have propagation loss in space, so the longer the distance to establish communication, the more gain is required to compensate for the power in communication. However, in the wireless communication device disclosed in Patent Document 1, although the direction of the directional beam radiated from the antenna is narrowed, sufficient gain cannot be secured, and there are cases where communication with a long distance cannot be secured.

[0005] The present invention has been made in consideration of the problems inherent in the conventional techniques, and an object of the present invention is to provide an antenna device capable of obtaining radio wave gain while ensuring isolation to prevent radio waves from leaking around. [Means for solving the problem]

[0006] An antenna device according to an embodiment of the present invention comprises a substrate, a transmitting antenna provided on the substrate, a receiving antenna provided on the same plane as the substrate plane on which the transmitting antenna is provided, a first dielectric lens having a convex shape in a first direction which is a direction perpendicular to the substrate plane of the substrate and at a position a predetermined distance away from the transmitting antenna in the first direction and in a second direction opposite to the first direction, and a second dielectric lens having a convex shape in the first direction and at a position a predetermined distance away from the receiving antenna in the first direction. Effect of the Invention

[0007] According to the present invention, it is possible to provide an antenna device that can ensure isolation to prevent leakage of radio waves while obtaining radio wave gain. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining wraparound in a communication system. [Diagram 2] 1 is a diagram for explaining the relationship between the distance between transmitting and receiving antennas and propagation loss. [Figure 3A] 1 is a diagram for explaining leakage from a transmitting antenna to a receiving antenna; [Figure 3B] 1A and 1B are diagrams for explaining a transmitting and receiving antenna using a shielding plate. [Figure 3C] 11A and 11B are diagrams for explaining limitations of a radiation pattern caused by a shielding plate. [Figure 4] 1 is a diagram showing a configuration of an antenna device according to an embodiment of the present invention; [Diagram 5]3A and 3B are diagrams for explaining transmission and reception coverage areas of the antenna device according to the embodiment. [Figure 6] 10 is a radiation pattern diagram for explaining leakage from a transmitting antenna to a receiving antenna when there is no shielding plate. FIG. [Figure 7] 10 is a radiation pattern diagram for explaining leakage from a transmitting antenna to a receiving antenna when a shielding plate is installed. FIG. [Figure 8A] 5 is a radiation pattern diagram for explaining leakage from a transmitting antenna to a receiving antenna in the antenna device according to the present embodiment. FIG. [Figure 8B] 10 is a radiation pattern diagram for explaining leakage from a transmitting antenna to a receiving antenna when no lens is provided. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The antenna device 10 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0010] 1 is a diagram for explaining leakage in a communication system 1. Radio over fiber (RoF) is one of the methods for relaying and transmitting a radio signal to a mobile terminal 30 in an area (dead zone) where a radio signal (radio wave) from a base station 20 does not reach. In the RoF of the communication system 1, a radio signal received by a receiving antenna 200 is converted into an optical signal by the RoF_Tx50 and transmitted to an optical fiber 40. Also, in the communication system 1, an optical signal from the optical fiber 40 is converted into an electric signal by the RoF_Rx60 and transmitted to the mobile terminal 30 via the transmitting antenna 100. Also, in the communication system 1, a radio signal is transmitted from the mobile terminal 30 to the base station 20 via the receiving antenna 200, the RoF_Tx50, the optical fiber 40, the RoF_Rx60, and the transmitting antenna 100.

[0011] Fifth generation wireless communication uses the TDD (Time Division Duplex) method, which transmits and receives signals on the same frequency, so the transmitted radio waves will leak back to the receiving end, as shown in Figure 1. When radio waves leak back, a signal loop occurs in the RoF, causing oscillation, which not only disables communication but can also lead to damage to equipment. Therefore, there is a need to prevent leakage, as mentioned in the conventional technology section.

[0012] To prevent radio waves from leaking out, it is necessary to ensure isolation greater than the system gain. Figure 2 is a diagram explaining the relationship between the distance between transmitting and receiving antennas and propagation loss. As shown in Figure 2, free space propagation loss at 28 GHz is attenuated by 60 dB or more when the transmitting antenna and the receiving antenna are separated by 1 m. Therefore, the further away one tries to establish communication, the more gain is required to compensate for the power in communication. On the other hand, in order to ensure isolation greater than the gain, it is sufficient to increase the distance between the transmitting and receiving antennas, but spacing the antennas several meters apart as in Figure 2 is not realistic for use inside a building.

[0013] 3A is a diagram for explaining leakage from the transmitting antenna 100 to the receiving antenna 200. As an example of an antenna used for RoF, a patch antenna having a pattern formed on a circuit board (substrate 300) as shown in FIG. 3A is shown.

[0014] Fig. 3B is a diagram for explaining a transmitting / receiving antenna using a shielding plate 400. Since interference occurs between the transmitting and receiving antennas, a possible measure to take while reducing the distance between the receiving antennas 200 is to use a shielding plate 400 as shown in Fig. 3B. However, in the configuration of the transmitting and receiving antennas shown in Fig. 3B, diffraction occurs, making it difficult to ensure sufficient isolation.

[0015] Fig. 3C is a diagram for explaining the restriction of the radiation pattern by the shielding plate 400. As shown in Fig. 3C, the presence of the shielding plate 400 blocks a part of the desired radiation direction, so securing the radiation area and securing the isolation may be in conflict with each other.

[0016] In the antenna device 10 according to this embodiment, a dielectric lens is used as a method of suppressing this diffraction, as shown in FIG. 4. The antenna device 10 according to this embodiment focuses the radio waves near the dielectric lens, thereby suppressing divergence in directions other than the radiation direction and reducing the amount of diffraction. In this embodiment, the dielectric lens includes a first dielectric lens 110 on the transmitting side and a second dielectric lens 210 on the receiving side. In the following description, when there is no need to distinguish between the first dielectric lens 110 and the second dielectric lens 210 on the receiving side, they will simply be referred to as "dielectric lenses."

[0017] (Regarding the antenna device 10 according to this embodiment) Fig. 4 is a diagram showing the configuration of an antenna device 10 according to this embodiment. As shown in Fig. 4, the antenna device 10 according to this embodiment includes a transmitting antenna 100, a first dielectric lens 110 for transmission, a receiving antenna 200, and a second dielectric lens 210 for reception.

[0018] 4, the transmitting antenna 100 is provided on a substrate 300. The receiving antenna 200 is provided on the same substrate plane as the substrate plane on which the transmitting antenna 100 is provided.

[0019] In the example shown in Fig. 4, the direction in which the transmitting antenna 100 and the receiving antenna 200 are provided is defined as the X-axis direction in a substrate plane formed by the substrate 300. That is, in the example shown in Fig. 4, the X-axis direction corresponds to the left-right direction in the figure.

[0020] In addition, the direction perpendicular to the X-axis direction is defined as the Y-axis direction in the substrate plane in Fig. 4. That is, in the example shown in Fig. 4, the substrate plane corresponds to the XY plane formed by the X-axis and Y-axis.

[0021] 4, the direction perpendicular to the substrate plane is defined as the Z-axis direction. In the following description, the upward direction in FIG. 4 is defined as the first direction, and the downward direction in FIG. 4 is defined as the second direction.

[0022] The first dielectric lens 110 is provided at a position a predetermined distance away from the transmitting antenna 100 in a first direction that is a direction perpendicular to the substrate plane of the substrate 300. The first dielectric lens 110 is a dielectric lens having a convex shape formed in the first direction and in a second direction opposite to the first direction. The first dielectric lens 110 generates a focal point for constricting the electric field in the first direction and the second direction.

[0023] The second dielectric lens 210 is provided at a position a predetermined distance away from the receiving antenna 200 in the first direction. The second dielectric lens 210 is a dielectric lens having a convex shape formed in the first and second directions. The second dielectric lens 210 generates a focal point for constricting the electric field in the first and second directions.

[0024] The dielectric lens is made of a dielectric material and has the function of converging electromagnetic waves. Since the electric field is narrowed at the point where the electric field is focused by the dielectric lens, the isolation (coupling) between the transmitter and receiver is weak. In addition, the dielectric lens can reduce the electric field that reaches the shielding plate 400 described below, and can also reduce diffraction caused by the electric field that reaches the shielding plate 400.

[0025] Conventionally, antennas using dielectric lenses are focused on the local station side (transmitting and receiving antenna side) to obtain gain, and are not focused on the communication partner side. The antenna device 10 according to this embodiment is characterized in that the dielectric lens is made convex toward both the local station side (transmitting and receiving antenna side) and the communication partner side, thereby focusing radio waves on both the local station side (transmitting and receiving antenna side) and the communication partner side.

[0026] In this embodiment, the dielectric lens is shown to have a convex shape to focus the electromagnetic wave and form an image, but the shape of the dielectric lens does not limit the configuration of the embodiment. For example, as long as it is possible to focus the electromagnetic wave and form an image, a configuration using a reflector on a concave dielectric lens may be applied. In addition, the dielectric lens is not limited to a convex or concave shape, and may be composed of a fullness lens.

[0027] Furthermore, the antenna device 10 according to this embodiment can vary the radiation angle by changing the focal length, making it possible to manipulate the radiation pattern. In this embodiment, the dielectric lens may be fixed above the substrate plane of the transmitting antenna 100 and / or the receiving antenna 200 using a predetermined fixing part 500. For example, a fixing part 500 as shown in Fig. 8A described later may be used.

[0028] Furthermore, with regard to fixing the dielectric lens, for example, a groove can be cut into the ring of the dielectric lens and screwed into the part that supports the dielectric lens, making it possible to change the distance between the dielectric lens and the antenna while fixing the dielectric lens.

[0029] In the second dielectric lens 210, which is the dielectric lens on the receiving antenna 200 side, electric fields incident from other than the focused area become virtual images through the dielectric lens, making it difficult to receive electric fields from directions other than the intended direction, which is advantageous for ensuring isolation.

[0030] Furthermore, it is possible to change the focal length by changing the curvature of the dielectric lens of the antenna device 10 according to this embodiment and the dielectric constant of the material. For example, when the antenna device 10 according to this embodiment is used on land, it is sufficient that the dielectric constant (relative dielectric constant) in air exceeds 1. In the antenna device 10 according to this embodiment, the higher the dielectric constant, the thinner the dielectric lens can be made.

[0031] In addition, since the larger the receiving aperture, the higher the receiving power, it is preferable to use a larger dielectric lens. The size of the dielectric lens may be determined based on the constraints imposed by the installation environment of the antenna device 10. The size of the dielectric lens may be smaller than the size of the antenna of the transmitting antenna 100 and / or the receiving antenna 200.

[0032] In addition, the antenna can be made capable of changing the radiation direction by shifting the positional relationship between the transmitting and receiving antennas and the dielectric lens from the same axis. The same axis corresponds to an axis extending from the transmitting antenna 100 and the receiving antenna 200 in a direction perpendicular to the substrate plane (Z-axis direction, first direction).

[0033] Moreover, the antenna device 10 according to this embodiment includes a shielding plate 400 extending in a first direction from the substrate 300 between the transmitting antenna 100 and the receiving antenna 200 on the substrate 300. The width (length in the Y-axis direction) of this shielding plate 400 is longer than the lengths of the transmitting antenna 100 and the receiving antenna 200 in the Y-axis direction. The Y-axis direction corresponds to the third direction. This enables the antenna device 10 to more reliably ensure isolation of the radio waves radiated from the transmitting antenna 100.

[0034] 5 is a diagram for explaining the transmission and reception coverage area of ​​the antenna device 10 according to this embodiment. It is assumed that an area equal to or greater than the focal length of the dielectric lens is used as the coverage area in which communication is possible.

[0035] (Regarding radiation pattern) Fig. 6 is a radiation pattern diagram for explaining leakage from the transmitting antenna 100 to the receiving antenna 200 when there is no shielding plate 400. Fig. 6 shows the results of an electromagnetic field analysis of the electric field at 28 GHz when the patch antennas are arranged on the substrate plane. It is assumed that the transmitted electric field is about 100 V / m and is applied to the receiving antenna 200.

[0036] Fig. 7 is a radiation pattern diagram for explaining the leakage from the transmitting antenna 100 to the receiving antenna 200 when the shielding plate 400 is installed. In the radiation pattern shown in Fig. 7, the influence of leakage was confirmed by installing a metal shielding plate 400 between the transmitting and receiving antennas. By installing the shielding plate 400, diffraction occurs at the end of the shielding plate 400 toward the receiving antenna 200.

[0037] Fig. 8A is a radiation pattern diagram for explaining leakage from the transmitting antenna 100 to the receiving antenna 200 in the antenna device 10 according to this embodiment. Note that, in the example shown in Fig. 8A, in order to explain leakage from the transmitting antenna 100, a configuration is adopted in which the second dielectric lens 210 is not provided.

[0038] Since the shielding plate 400 alone cannot prevent diffraction, Fig. 8A shows the analysis results of the radiation pattern from the antenna with and without the dielectric lens focused as in Fig. 4. In Fig. 6 above, the maximum electric field strength is shown as 200 V / m, but in Fig. 8A, the maximum electric field strength is set to 10 V / m, which is 1 / 20 of the original value, in order to see the strength of the weakened diffracted area.

[0039] As shown in FIG. 8A, by focusing the radiation pattern using a dielectric lens (first dielectric lens 110), the strength of the electric field that wraps around the space above the receiving antenna 200 can be reduced, thereby ensuring isolation.

[0040] Fig. 8B is a radiation pattern diagram for explaining the leakage from the transmitting antenna to the receiving antenna when there is no dielectric lens. As shown in the elliptical area in Fig. 8B, when there is no dielectric lens, radio waves with a stronger electric field intensity (radio waves in the dark area in the figure) are diffracted compared to when there is a dielectric lens.

[0041] In the above example, the analysis was performed by installing a dielectric lens only on the transmitting antenna 100 side, but it is possible to limit the reception of diffracted electric fields by also installing a dielectric lens on the receiving antenna 200 side. Furthermore, the dielectric lens may be installed not only on the transmitting antenna 100 side, but also on the receiving antenna 200 side. Furthermore, a dielectric lens may be installed for each of the transmitting antenna 100 and the receiving antenna 200 as shown in FIG. 4.

[0042] As described above, the antenna device 10 according to this embodiment includes the substrate 300, the transmitting antenna 100 provided on the substrate 300, and the receiving antenna 200 provided on the same plane as the substrate plane on the substrate 300 on which the transmitting antenna 100 is provided. The antenna device 10 also includes a first dielectric lens 110 that is convex in the first direction, which is a direction perpendicular to the substrate plane of the substrate 300, at a position spaced a predetermined distance from the transmitting antenna 100. The antenna device 10 also includes a second dielectric lens 210 that is convex in the first direction and in the second direction opposite to the first direction, at a position spaced a predetermined distance from the receiving antenna 200 in the first direction.

[0043] This allows the antenna device 10 to obtain radio wave gain while ensuring isolation to prevent radio waves from leaking around.

[0044] Furthermore, the first dielectric lens 110 of the antenna device 10 may generate a focal point for constricting the electric field in the first direction and the second direction. This allows the antenna device 10 to obtain a gain for the radio wave transmitted from the transmitting antenna 100 while ensuring isolation for preventing the radio wave from wandering around.

[0045] Furthermore, the second dielectric lens 210 of the antenna device 10 may generate a focal point for constricting the electric field in the first direction and the second direction. This allows the antenna device 10 to obtain a gain for the radio wave transmitted to the receiving antenna 200 while ensuring isolation for preventing the radio wave from wandering around.

[0046] Furthermore, the antenna device 10 may include a shielding plate 400 extending in a first direction from the substrate 300 between the transmitting antenna 100 on the substrate 300 and the receiving antenna 200. This makes it possible for the antenna device 10 to more reliably ensure isolation between the transmitting antenna 100 and the receiving antenna 200 to prevent radio waves from leaking between them.

[0047] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. The components described above include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described above can be appropriately combined. Various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0048] The transmitting antenna 100 and / or the receiving antenna 200 of the antenna device 10 may be configured with an antenna such as a patch, a horn, or a slit. The polarization may be circular or linear. The dielectric material applied to the dielectric lens may be selected based on weather resistance, etc., and the material is not specified. The antenna device 10 may use a radio wave absorber in addition to the shielding plate 400, or may be configured by combining the shielding plate 400 with a radio wave absorber. Furthermore, the dielectric lens may also serve as a case (radome).

[0049] The features of the antenna device 10 are described below.

[0050] The antenna device 10 according to the first aspect includes a substrate 300, a transmitting antenna 100 provided on the substrate 300, and a receiving antenna 200 provided on the same substrate plane as the substrate plane on which the transmitting antenna 100 is provided on the substrate 300. The antenna device 10 also includes a first dielectric lens 110 having a convex shape formed in the first direction, which is a direction perpendicular to the substrate plane of the substrate 300, at a position spaced a predetermined distance from the transmitting antenna 100 in the first direction and in a second direction opposite to the first direction. The antenna device 10 also includes a second dielectric lens 210 having a convex shape formed in the first direction and in the second direction at a position spaced a predetermined distance from the receiving antenna 200 in the first direction.

[0051] According to the above configuration, the antenna device 10 can obtain radio wave gain while ensuring isolation to prevent radio waves from leaking around.

[0052] The first dielectric lens 110 of the antenna device 10 according to the second embodiment may generate a focal point for confining the electric field in the first direction and the second direction.

[0053] According to the above configuration, the antenna device 10 can obtain gain for the radio waves transmitted from the transmitting antenna 100, while ensuring isolation to prevent the radio waves from leaking out.

[0054] The second dielectric lens 210 of the antenna device 10 according to the third embodiment may generate a focal point for confining the electric field in the first direction and the second direction.

[0055] According to the above configuration, the antenna device 10 can obtain a gain for the radio wave transmitted to the receiving antenna 200, while ensuring isolation to prevent the radio wave from wandering around.

[0056] The antenna device 10 according to the fourth embodiment may include a shielding plate 400 between the transmitting antenna 100 and the receiving antenna 200 on the substrate 300, the shielding plate 400 extending from the substrate 300 in a first direction.

[0057] According to the above configuration, the antenna device 10 can more reliably ensure isolation between the transmitting antenna 100 and the receiving antenna 200 to prevent radio waves from leaking in between. [Explanation of symbols]

[0058] 1. Communication Systems 20 base station 30 Mobile Devices 40 Optical Fiber 50 RoF_Tx 60 RoF_Rx 10 Antenna device 100 transmit antennas 110 First dielectric lens 200 receiving antenna 210 Second dielectric lens 300 Substrates 400 Shielding plate 500 Fixed part

Claims

1. A substrate; A transmitting antenna provided on the substrate; a receiving antenna provided on the same plane as the plane of the substrate on which the transmitting antenna is provided; a first dielectric lens having a convex shape formed in a first direction, which is a direction perpendicular to the substrate plane of the substrate, at a position spaced a predetermined distance from the transmitting antenna, the first direction and a second direction opposite to the first direction; a second dielectric lens having a convex shape formed in the first direction and the second direction at a position spaced a predetermined distance from the receiving antenna in the first direction; An antenna device comprising:

2. The antenna device according to claim 1 , wherein the first dielectric lens generates a focal point for constricting an electric field in the first direction and the second direction.

3. The antenna device according to claim 1 , wherein the second dielectric lens generates a focal point for constricting an electric field in the first direction and the second direction.

4. 4. The antenna device according to claim 1, further comprising a shielding plate disposed between the transmitting antenna and the receiving antenna on the substrate and extending from the substrate in the first direction.

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