Antenna cover

Abstract

To provide an antenna cover for enabling proper communication with an in-vehicle apparatus of a target vehicle through a simple configuration.SOLUTION: An antenna cover covering a directional antenna includes: a cover portion that, when attached to the antenna, covers the backward and lateral direction of the antenna in the direction of radio wave radiation and has an opening which opens in the direction from the antenna to a predetermined radiation range; and a radio wave absorber provided on an inner surface of the cover portion facing the antenna.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Various methods have been proposed to properly perform DSRC communication between an on-board device installed in a vehicle and a roadside device at a toll booth on a highway, etc., without miscommunication. For example, a technique has been proposed in which two communication means including two antennas capable of communication and a camera capable of photographing the vehicle are provided, and the directivity of the second antenna is controlled according to the state of communication via the first antenna and the analysis result of the image photographed by the camera (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-258539 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology described in Patent Document 1 requires the provision of two communication means and a camera, and the combination and control of these, which requires expensive equipment and complex processing. For this reason, it has been difficult to easily utilize the conventional technology described in Patent Document 1 in places other than large-scale facilities such as expressways.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an antenna cover that can appropriately perform communication with a communication device such as an on-board unit of a vehicle located within a predetermined range, using a simple configuration. [Means for solving the problem]

[0006] The above object can be achieved by the following means.

[0007] The antenna cover is configured to cover a directional antenna. The antenna cover has a cover portion and a radio wave absorber. When attached to the antenna, the cover portion covers the rear and sides in the direction of radio wave radiation from the antenna, and has an opening that opens in the direction from the antenna toward a predetermined radiation range. The radio wave absorber is provided on the inner surface of the cover portion that faces the antenna. Effect of the Invention

[0008] According to the antenna cover of the present invention, the cover is configured to cover a directional antenna, and when attached to the antenna, the cover has an opening that covers the rear and sides of the antenna in the radiation direction of radio waves and opens in the direction from the antenna to a predetermined radiation range, and a radio wave absorber is provided on the inner surface of the cover facing the antenna. As a result, radio waves are radiated from the antenna through the opening in the direction toward the predetermined radiation range, and in directions other than the direction toward the predetermined radiation range, most of the energy radiated from the radio waves is absorbed by the radio wave absorber, resulting in radiation below an allowable level. Therefore, it is possible to control so that radio waves are not radiated above an allowable level outside the predetermined radiation range, and a simple configuration makes it possible to appropriately communicate with the vehicle-mounted device of the target vehicle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an environment in which an antenna to which the antenna cover of the present invention is applied is installed, as viewed from the side. [Diagram 2] 1 is a schematic diagram showing an environment in which an antenna to which the antenna cover of the present invention is applied is installed, as viewed from above. [Figure 3A] 2 is a schematic front view showing the antenna cover shown in FIG. 1 being locked from behind in the direction of radiation of radio waves from the antenna. [Figure 3B]2 is a schematic side view showing the antenna cover shown in FIG. 1 being locked from behind in the direction of radiation of radio waves from the antenna. [Figure 4A] FIG. 2 is a schematic front view of the antenna cover. [Figure 4B] FIG. 4 is a schematic rear view of the antenna cover. [Figure 4C] FIG. 4 is a schematic right side view of the antenna cover. [Figure 4D] FIG. 2 is a schematic top view of the antenna cover. [Figure 4E] FIG. 2 is a schematic bottom view of the antenna cover. [Diagram 5] FIG. 4B is a cross-sectional view taken along line II in FIG. 4D. [Figure 6] 11 is a diagram for explaining how the antenna cover controls the radiation of radio waves from the antenna so that the radiation does not exceed an allowable level outside a predetermined radiation range. FIG. [Figure 7] 10A and 10B are diagrams for explaining radiation of radio waves from an antenna according to a comparative example. [Figure 8] 10A and 10B are diagrams for explaining the state of radiation of radio waves from an antenna to which an antenna cover according to a comparative example is applied. [Figure 9] 2 is a diagram for explaining how, in the environment shown in FIG. 1, the antenna cover controls the radiation of radio waves from the antenna so that the radiation does not exceed an allowable level outside a predetermined radiation range. FIG. [Figure 10] 3 is a diagram for explaining how, in the environment shown in FIG. 2, the antenna cover controls the radiation of radio waves from the antenna so that the radiation does not exceed an allowable level outside a predetermined radiation range. [Figure 11A] FIG. 11 is a schematic rear view of an antenna cover according to a modified example. [Figure 11B] FIG. 11B is a schematic top view of the antenna cover shown in FIG. 11A. [Figure 11C] FIG. 11C is a cross-sectional view taken along line II-II in FIG. 11B. [Figure 12]11B is a diagram for explaining how, in the environment shown in FIG. 1, the antenna cover according to the modified example shown in FIG. 11A controls the radiation of radio waves from the antenna so that it does not exceed an allowable level outside a predetermined radiation range. FIG. [Figure 13] 11B is a diagram for explaining how, in the environment shown in FIG. 2, the antenna cover according to the modified example shown in FIG. 11A controls the radiation of radio waves from the antenna so that the radiation does not exceed an allowable level outside a predetermined radiation range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated description will be omitted. In addition, the dimensional ratios of the drawings may be exaggerated for the convenience of explanation and may differ from the actual ratios.

[0011] (Overall composition) FIG. 1 is a schematic diagram showing an environment in which an antenna to which an antenna cover of the present invention is applied is installed, as viewed from the side.

[0012] As shown in FIG. 1, an antenna 500 for communicating with an on-board device mounted on a vehicle is installed above a parking space for parking a vehicle provided on the ground. The antenna 500 is a directional antenna and is installed so as to radiate radio waves in a downward radiation direction from the installed position. An antenna cover 100 is attached to the antenna 500. The antenna cover 100 controls the radio waves radiated from the antenna 500 so that they do not exceed an allowable level outside a predetermined radiation range. The antenna 500 is, for example, an ETC antenna for performing DSRC communication using radio waves in the 5.8 GHz band. In this embodiment, an example will be described in which the antenna 500 is a device including an antenna element that functions as an aerial and a transmitter / receiver (wireless device or transceiver) that is connected to the antenna element and transmits and receives radio waves. However, the antenna 500 only includes a mechanism consisting of an antenna element that functions as an aerial and a power supply unit, and the transmitter / receiver may be provided externally as a separate configuration and connected by a cable or the like.

[0013] The antenna 500 is, for example, housed and fixed inside the antenna cover 100. The antenna cover 100 is engaged with a support portion 200 erected near a parking space. The support portion 200 has a support pole 210 and an arm portion 220. The support pole 210 is vertically extended 2.5 to 5.0 m above the ground. The arm portion 220 is extended from the upper portion of the support pole 210 in a direction intersecting the support pole 210. The arm portion 220 is horizontally extended 0.2 to 5.0 m from the position of the support pole 210. The support pole 210 is fixed to an embedded portion 230, and is supported so as to be erected vertically by embedding the embedded portion 230 in the ground.

[0014] FIG. 2 is a schematic diagram showing an environment in which an antenna to which the antenna cover of the present invention is applied is installed, as viewed from above.

[0015] As shown in Fig. 2, the antenna 500, antenna cover 100 and support unit 200 are provided, for example, between two parking spaces each capable of parking one vehicle. The support pillar 210 of the support unit 200 is provided, for example, at the rear side of the parking space (the upper side in Fig. 2, the side farther from the vehicle passage through which the vehicles pass). The arm unit 220 extends from the rear side of the parking space toward the front side (the lower side in Fig. 2, the side closer to the vehicle passage through which the vehicles pass). The antenna 500 and antenna cover 100 are provided at the tip of the arm unit 220, i.e., at the front side of the parking space.

[0016] Fig. 3A is a schematic front view showing the antenna cover shown in Fig. 1 being fastened from behind in the direction of radio wave radiation from the antenna, and Fig. 3B is a schematic side view showing the antenna cover shown in Fig. 1 being fastened from behind in the direction of radio wave radiation from the antenna.

[0017] 3A and 3B, the antenna cover 100 has a cover portion 110 and a locking portion 120. When the antenna cover 100 is attached to the antenna 500, the cover portion 110 covers the antenna 500 on the rear and sides in the radiation direction of radio waves emitted by the antenna 500, and opens the radiation direction of the radio waves of the antenna 500 (the direction toward a predetermined radiation range). In other words, when the surface facing the radiation direction of the radio waves of the antenna 500 is defined as the front surface, the surface opposite the radiation direction of the radio waves is defined as the rear surface, and the surfaces other than the front and back are defined as sides, the cover portion 110 covers the rear and side surfaces of the antenna 500 and opens the front surface of the antenna 500.

[0018] The locking portion 120 is provided to lock the antenna cover 100 from the rear in the radiation direction of radio waves emitted by the antenna 500 when the antenna cover 100 is attached to the antenna 500. The locking portion 120 is fixed to a connecting portion 121 for engaging with and connecting to the support portion 200.

[0019] Figure 4A is a schematic front view of the antenna cover. Figure 4B is a schematic rear view of the antenna cover. Figure 4C is a schematic right side view of the antenna cover. Figure 4D is a schematic top view of the antenna cover. Figure 4E is a schematic bottom view of the antenna cover. Figure 5 is a cross-sectional view taken along the line I-I of Figure 4D.

[0020] As shown in FIGS. 4A to 4D, the cover portion 110 has side surfaces 111 (side surface 111a on the front side, side surface 111b on the rear side, side surface 111c on the right side, and side surface 111d on the left side) and a top surface 112. The cover portion 110 is formed of a metal such as aluminum that does not transmit radio waves radiated from the antenna, for example. Also, as shown in FIGS. 3A and 3B, each side surface of the cover portion 110 is formed to extend longer forward than the side surface of the antenna 500 in the radio wave radiation direction of the antenna 500 when the antenna cover 100 is attached to the antenna 500. That is, each side surface of the cover portion 110 is formed to cover each side surface of the antenna 500. Further, each side surface of the cover portion 110 is also used for applications such as increasing or decreasing the radiation range or deforming the shape of the radiation range by adjusting the length that extends forward from the side surface of the antenna 500.

[0021] As shown in FIGS. 4E and 5, a radio wave absorber 130 is provided on the inner surface of the cover portion 110 facing the antenna 500. The radio wave absorber 130 is, for example, adhered to the inner surface of the cover portion 110 and provided over the entire inner surface of the cover portion 110. The radio wave absorber 130 is formed of, for example, silicon. As the radio wave absorber 130, various known radio wave absorbers can be appropriately used, and for example, a radio wave absorber formed in a sheet shape is preferably used. When a metal member such as an aluminum thin film is provided on the side of the radio wave absorber 130 facing the cover portion 110, the cover portion 110 may be formed of a material other than metal. Also, as shown in FIGS. 4E and 5, the cover portion 110 is provided with an opening 114 that opens in the direction from the antenna 500 toward the radio wave radiation range of the antenna 500.

[0022] FIG. 6 is a diagram for explaining how the radiation of radio waves from the antenna is controlled by the antenna cover so that it does not exceed an allowable level outside a predetermined radiation range.

[0023] As shown in FIG. 6, in the antenna 500 to which the antenna cover 100 according to this embodiment is attached, the rear and sides in the radiation direction of the radio waves of the antenna 500 are covered by the radio wave absorber 130 provided on the inner surface of the cover part 110. In addition, the direction from the antenna 500 toward the predetermined radiation range is opened by the opening 114. The radio waves radiated from the antenna 500 are radiated without being blocked in the direction toward the predetermined radiation range, and in other directions, the radio waves are radiated only below the allowable level because a certain amount of energy is absorbed by the radio wave absorber 130. This makes it possible to control the radio waves radiated from the antenna 500 so that they do not exceed the allowable level outside the predetermined radiation range. The allowable level is a threshold value of the electric field strength that can be received on the receiver side that receives the radio waves, and is determined in advance according to the specifications of the device on the receiver side, experimental results, etc. For example, if the antenna 50 is an ETC antenna for performing DSRC communication using radio waves in the 5.8 GHz band, the ETC vehicle-mounted device that receives the radio waves can generally receive radio waves having an electric field strength of about minus 65 dBm at the receiving point. In this case, the tolerance level may be set to, for example, about minus 65 dBm. The tolerance level may be changed as appropriate depending on the purpose of control, the required accuracy, etc. For example, when the tolerance level is set more strictly, a value smaller than the above value may be set.

[0024] Fig. 7 is a diagram for explaining the state of radio wave radiation by an antenna according to a comparative example. The antenna 500 in Fig. 7 is the same as the antenna 500 in Fig. 6. The comparative example in Fig. 7 differs from the example in Fig. 6 in that the antenna cover 100 of the present embodiment is not attached to the antenna 500.

[0025] As shown in Fig. 7, the main lobe of the radio wave radiated from the antenna 500 is narrowed down to a certain range according to the directivity of the antenna 500, but since the antenna 500 also radiates back lobes and side lobes of a certain level from the rear and sides of the antenna, respectively, it is extremely difficult to control the radiation of the radio wave to a predetermined radiation range as shown by the dashed line (corresponding to the predetermined radiation range in Fig. 6). For example, it is possible to further control the radiation range of the radio wave by combining multiple antennas as the antenna 500 and controlling the phases of the radio waves output from each antenna to be different, but in that case, the configuration and control of the antenna 500 become complicated. In that case, it is not possible to control the radiation of radio waves above a permissible level outside the predetermined radiation range with a simple configuration as in the embodiment of the present invention.

[0026] Fig. 8 is a diagram for explaining the state of radio wave radiation by an antenna to which an antenna cover according to a comparative example is applied. The antenna 500 in Fig. 8 is the same as the antenna 500 in Fig. 6. The comparative example in Fig. 8 differs from the embodiment in Fig. 6 in that the antenna cover 900 attached to the antenna 500 does not have the radio wave absorber 130 as the antenna cover 100 in Fig. 6 does.

[0027] As shown in Fig. 8, radio waves emitted from the antenna 500 are emitted without being blocked in the direction toward the predetermined radiation range, but are reflected by the inner surface of the antenna cover 900 in other directions, and the reflected waves are emitted in various directions. Therefore, it is extremely difficult to control the radiation of radio waves so that they do not exceed an allowable level outside the predetermined radiation range (corresponding to the predetermined radiation range in Fig. 6) as shown by the dashed line. Note that if the antenna cover 900 is formed of a material that transmits radio waves, such as resin, the radio waves are not reflected by the inner surface of the antenna cover 900, and the radio waves are emitted in the same manner as in the state shown in Fig. 7. Therefore, in this case as well, it is extremely difficult to control the radiation of radio waves so that they do not exceed an allowable level outside the predetermined radiation range.

[0028] Fig. 9 is a diagram for explaining how the antenna cover controls the radiation of radio waves from the antenna so that it does not exceed an allowable level outside a predetermined radiation range in the environment shown in Fig. 1. Fig. 10 is a diagram for explaining how the antenna cover controls the radiation of radio waves from the antenna so that it does not exceed an allowable level outside a predetermined radiation range in the environment shown in Fig. 2.

[0029] As shown in Figs. 9 and 10, by mounting the antenna cover 100, the radio waves emitted from the antenna 500 are controlled so as not to exceed a permissible level outside a predetermined radiation range. The antenna 500, the antenna cover 100, and the support part 200 can be installed so that the ETC vehicle unit mounted on the vehicle entering and exiting the parking space stops in the predetermined radiation range or passes through the predetermined radiation range. For example, as shown in Fig. 10, the antenna 500, the antenna cover 100, and the support part 200 are installed so that a vehicle passage through which vehicles other than the vehicle using the target parking space may pass is not included in the predetermined radiation range, and a vehicle entering the parking space from the vehicle passage passes through the predetermined radiation range. This allows communication with the ETC vehicle unit of the vehicle using the parking space to be properly performed, and for example, the payment process for parking fees can be properly performed using information on the ETC vehicle unit mounted on the vehicle and information on the ETC card inserted in the ETC vehicle unit. In contrast, when using an antenna or antenna cover according to the comparative example as shown in Figures 7 and 8, it is not possible to control the radio waves output from the antenna so that they do not exceed the allowable level outside the specified radiation range, and the radio waves are radiated over a wide range. Therefore, there is a possibility that communication will be performed with ETC on-board units installed in vehicles other than the vehicle using the target parking space, and it is not possible to properly execute the parking fee settlement process using the above-mentioned information on the ETC on-board unit or the ETC card, etc.

[0030] As described above, the antenna cover 100 is configured to cover a directional antenna, and when attached to the antenna 500, the cover portion 110 has an opening 114 that covers the rear and sides of the antenna 500 in the radiation direction of radio waves and opens the direction from the antenna toward a predetermined radiation range, and the radio wave absorber 130 is provided on the inner surface of the cover portion 110 facing the antenna 500. As a result, radio waves are emitted from the antenna 500 in the direction toward the predetermined radiation range through the opening 114, and in directions other than the direction toward the predetermined radiation range, the radio waves are absorbed by the radio wave absorber 130. Therefore, it is possible to control the radiation of radio waves above an allowable level not to be emitted outside the predetermined radiation range, and a simple configuration makes it possible to appropriately communicate with a communication device such as an on-board device of a vehicle that is present within the predetermined range.

[0031] For example, it is possible to control the radio wave radiation range by combining multiple antennas as antenna 500 and controlling the phase of the radio waves output from each antenna to be different; however, in that case, the configuration and control of antenna 500 will become complicated, and it is not possible to control the radiation of radio waves above an allowable level outside a specified radiation range with a simple configuration, as in the embodiment of the present invention.

[0032] Furthermore, the antenna cover 100 is formed such that, when attached to the antenna 500, the side surface of the cover portion 110 extends further forward in the radiation direction than the side surface of the antenna 500. This allows the radio wave absorber 130 provided on the inner surface of the cover portion 110 to effectively absorb radio waves output from the antenna 500 that are radiated in directions other than a predetermined radiation range (outward).

[0033] Moreover, the radio wave absorber 130 of the antenna cover 100 is formed of, for example, silicon. This makes it possible to effectively absorb radio waves output from the antenna 500 that are radiated in directions other than the predetermined radiation range.

[0034] The antenna cover 100 further includes a locking portion 120 for locking the antenna cover 100 from the rear in the direction of radio wave radiation from the antenna 500. The antenna cover 100 is installed on the top of a support pole 210 that is vertically extended 2.5 to 5.0 m above the ground in a direction intersecting the support pole, and is locked by the locking portion 120 at the tip of an arm portion 220 that is horizontally extended 0.2 to 5.0 m from the support pole. This allows the antenna 500 and the antenna cover 100 to be fixed at any position above a predetermined range, such as a parking space, and allows appropriate communication to be performed between the antenna cover 100 and the vehicle-mounted device of the vehicle without impeding the passage of the vehicle entering and leaving the parking space.

[0035] (Modification) Fig. 11A is a schematic rear view of an antenna cover according to a modified example, Fig. 11B is a schematic top view of the antenna cover shown in Fig. 11A, and Fig. 11C is a cross-sectional view taken along line II-II in Fig. 11B.

[0036] As shown in FIGS. 11A to 11C, an opening 115 is provided in a side surface 111b on the rear side, which is one side surface of the cover portion 110 of the antenna cover 100. For example, the length of the side surface 111b in the direction of radiation of radio waves by the antenna 500 is made shorter than the lengths of the other side surfaces 111a, 111c, and 111d, thereby forming the opening 115. The method of forming the opening 115 is not limited to the above method, and the opening 115 may be formed by providing a hole or a notch in the side surface 111b. In addition, in the above embodiment, the opening 115 is formed continuous with the opening 114, but is not limited thereto, and the opening 115 may be formed as a separate opening not continuous with the opening 114. In addition, the opening 115 may be provided in a side surface other than the side surface 111b of the cover portion 110, or may be provided in a plurality of side surfaces.

[0037] Fig. 12 is a diagram for explaining how the antenna cover according to the modified example shown in Fig. 11A controls the antenna not to radiate radio waves at a level above the allowable level outside a predetermined radiation range in the environment shown in Fig. 1. Fig. 13 is a diagram for explaining how the antenna cover according to the modified example shown in Fig. 11A controls the antenna not to radiate radio waves at a level above the allowable level outside a predetermined radiation range in the environment shown in Fig. 2.

[0038] As shown in Fig. 12 and Fig. 13, by mounting the antenna cover 100 according to the modified example, the radio waves emitted from the antenna 500 are controlled so as not to radiate beyond a predetermined radiation range and at a tolerable level. As shown in Fig. 11A to Fig. 11C, an opening 115 that allows radio waves to pass is provided on the side surface 111b on the rear side of the cover part 110 of the antenna cover 100, so that the radiation range of the radio waves is wider on the rear side of the antenna cover 100 (the back side of the parking space) compared to the example of Fig. 9 and Fig. 10. In this way, even if the radiation range of the radio waves is wider on the rear side of the antenna cover 100 (the back side of the parking space), the radiation range of the radio waves is limited to within the target parking space. As a result, the vehicle passage and parking spaces other than the target parking space are not included in the radiation range of the radio waves, so that appropriate communication can be performed only with the ETC on-board unit of the vehicle using the target parking space.

[0039] As described above, according to the antenna cover 100 of the modified example, at least one side of the cover section 110 has an opening. In this way, by providing an opening on the side of the cover section 110, the radiation range of the radio waves from the antenna 500 can be controlled to a predetermined range, while suppressing the weight of the antenna cover 100, thereby achieving weight reduction. As a result, the antenna 500 to which the antenna cover 100 is attached can be stably fixed above a parking space or the like by the support section 200. In particular, when the cover section 110 is made of metal, the effect of weight reduction by providing the opening 115 is remarkable. In addition, by providing the opening 115, it is possible to save on the materials used in the cover section 110, thereby achieving cost reduction and resource conservation. Furthermore, by providing the opening 115, the area of ​​the inner surface of the cover section 110 can be reduced, and therefore the amount of the radio wave absorber 130 provided on the inner surface of the cover section 110 can also be reduced. As a result, the reduction in the amount of the radio wave absorber 130 used can also achieve weight reduction, cost reduction, and resource conservation of the antenna cover 100.

[0040] The present invention is not limited to the above-described embodiment (including the modified examples), and various modifications and improvements are possible within the scope of the claims.

[0041] For example, in the above embodiment, the cover portion 110 of the antenna cover 100 has the substantially rectangular upper surface 112 and the four side surfaces 111a to 111d, but is not limited thereto. For example, the cover portion 110 may be formed to have the upper surface 112 having a triangular or polygonal shape with pentagons or more sides, or a circular or elliptical shape, and each side surface corresponding to the upper surface 112.

[0042] In the above embodiment, the antenna 500 is an ETC antenna for performing DSRC communication using radio waves in the 5.8 GHz band, but the present invention is not limited to this. Antennas for outputting radio waves in various frequency bands and performing various types of communication may be used as the antenna 500.

[0043] In the above embodiment, the antenna 500 is described as being configured with a simple configuration having one antenna (aerial), but is not limited thereto. The antenna 500 may be configured with a complex configuration in which a plurality of antennas are combined and controlled to make the phases of the radio waves output from each antenna different. Even in this case, the application of the antenna cover 100 allows the radiation range of the radio waves from the antenna 500 to be more appropriately controlled. [Explanation of symbols]

[0044] 100 Antenna cover, 110 Cover part, 111, 111a, 111b, 111c, 111d side, 112 Top surface, 114 Aperture, 115 Aperture, 120 locking portion, 121 Connection part, 130 Radio wave absorber, 200 support part, 210 pillars; 220 Arm section, 230 Buried section, 500 antennas.

Claims

1. An antenna cover for covering a directional antenna, a cover portion that covers the rear and sides of the antenna in a direction of radio wave radiation when attached to the antenna and has an opening that opens in a direction from the antenna toward a predetermined radiation range; a radio wave absorber provided on an inner surface of the cover portion facing the antenna; a locking portion for locking the antenna cover from a rear side in the radiation direction, The antenna cover is installed on the top of a pole that extends vertically from the ground to a position 2.5 to 5.0 m above the ground, in a direction that intersects with the pole, and is engaged with the engaging portion at the tip of an arm that extends horizontally 0.2 to 5.0 m from the pole.

2. An antenna cover for covering a directional antenna, a cover portion that covers the rear and sides of the antenna in a direction of radio wave radiation when attached to the antenna and has an opening that opens in a direction from the antenna toward a predetermined radiation range; a radio wave absorber provided on an inner surface of the cover portion facing the antenna; and a locking portion for locking the antenna cover from behind in the radiation direction.

3. 3. The antenna cover according to claim 1, wherein a side surface of the cover portion is formed so as to extend forward in the radiation direction further than a side surface of the antenna when the cover portion is attached to the antenna.

4. The antenna cover according to claim 1 or 2, wherein at least one of the side surfaces of the cover portion has an opening.

5. The antenna cover according to claim 1 , wherein at least one side surface of the cover portion is formed to have a length in the radiation direction shorter than other side surfaces of the cover portion.

6. 3. The antenna cover according to claim 1, wherein the radio wave absorber is made of silicon.

7. The antenna cover according to claim 1 ; an antenna with the antenna cover attached; A support pillar extending vertically from the ground to a height of 2.5 to 5.0 m; An arm portion is provided at an upper portion of the support pillar, extending in a direction intersecting the support pillar and extending horizontally from the support pillar by 0.2 to 5.0 m; The antenna is an antenna system located at a height of 2.5m to 5.0m above the ground.

8. 8. The antenna system according to claim 7, wherein the antenna is an antenna for performing DSRC communication using radio waves in the 5.8 GHz band.

Images