Antenna device

Abstract

To expand a wireless communication service area on the ground using an antenna device placed in an underground space such as a manhole.SOLUTION: An antenna device, which is placed in an underground space extending from the ground surface toward the underground, includes an antenna body equipped with a vertically polarized array antenna and a horizontally polarized array antenna, and a hemispherical convex lens, with the convex lens positioned on the sky side of the antenna body and the spherical side of the convex lens facing toward the antenna body.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, an antenna device that is installed in a manhole is known (see, for example, Patent Document 1). The antenna device described in Patent Document 1 includes an antenna element, an installation stand on which the antenna element is installed, a container that has an open top surface that is the surface closest to the ground surface when installed underground and that houses the antenna element and the installation stand, and a lid that is made of FRP (Fiber Reinforced Plastics) and covers the opening of the container, and the installation stand is provided with a height adjustment mechanism that adjusts the distance from the antenna element to the lid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-177632 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional antenna device described above, adjustments can be made to satisfy the radio wave protection guidelines by adjusting the distance from the antenna element to the manhole cover, but since the antenna directivity is not taken into consideration, it is insufficient for expanding the wireless communication service area on the ground.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to expand the above-ground wireless communication service area of ​​an antenna device disposed in an underground space such as a manhole. [Means for solving the problem]

[0006] One aspect of the present invention is an antenna device that is placed in an underground space extending from the ground surface toward the underground, and comprises an antenna body equipped with a vertically polarized array antenna and a horizontally polarized array antenna, and a hemispherical convex lens, the convex lens being positioned on the sky side of the antenna body with the spherical side of the convex lens facing toward the antenna body. One aspect of the present invention is the antenna device described above, wherein a hemispherical recess is provided on the aspherical surface side of the convex lens. One aspect of the present invention is an antenna device in which the antenna body in the above-mentioned antenna device comprises six vertically polarized monopole antennas arranged at equal intervals on a first circumference and six horizontally polarized dipole antennas arranged at equal intervals on a second circumference, wherein a first array antenna is formed by three of the vertically polarized monopole antennas arranged at 0 degrees, 120 degrees and 240 degrees, a second array antenna is formed by three of the vertically polarized monopole antennas arranged at 60 degrees, 180 degrees and 300 degrees, a third array antenna is formed by three of the horizontally polarized dipole antennas arranged at 30 degrees, 150 degrees and 270 degrees, and a fourth array antenna is formed by three of the horizontally polarized dipole antennas arranged at 90 degrees, 210 degrees and 330 degrees. Effect of the Invention

[0007] According to the present invention, it is possible to obtain an effect that it is possible to expand the radio communication service area on the ground of an antenna device disposed in an underground space such as a manhole. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an explanatory diagram for explaining a configuration example of an antenna device according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram for explaining a configuration example of an antenna device according to an embodiment. [Diagram 3] FIG. 2 is an external view illustrating a configuration example of a convex lens according to an embodiment. [Figure 4] 1 is a diagram illustrating a configuration example of an antenna main body according to an embodiment; [Diagram 5] FIG. 4 is a dimensional diagram of an antenna body according to an embodiment. [Figure 6] FIG. 4 is a dimensional diagram of an antenna body according to an embodiment. [Figure 7] FIG. 2 is a dimensional diagram of an antenna device according to an embodiment. [Figure 8] 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. [Figure 9] 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. [Figure 10] 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. [Figure 11] 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. [Figure 12] 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. [Figure 13] 11A and 11B are diagrams illustrating a modified example of the antenna device according to the embodiment. [Figure 14] 11A and 11B are diagrams illustrating a modified example of the antenna device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are explanatory diagrams for explaining a configuration example of an antenna device according to an embodiment, where FIG. 1 is a diagram seen from a side and FIG. 2 is a diagram seen from above.

[0010] The antenna device according to this embodiment (the present antenna device) comprises an antenna body 10 and a hemispherical convex lens 50. The present antenna device is disposed inside a manhole 4. The manhole 4 is a space (underground space) formed underground 2. The manhole 4 is provided from the ground surface 3 toward the underground. A manhole cover 1 is provided on the ground surface 3 for the manhole 4. The manhole cover 1 is a lid that covers the manhole 4. The convex lens 50 is disposed inside the manhole 4 on the sky side of the antenna body 10.

[0011] The material of the manhole cover 1 is preferably a material that does not affect the radio wave propagation of the antenna device placed in the manhole 4. The material of the manhole cover 1 is, for example, FRP (Fiber Reinforced Plastics).

[0012] A cable 20 such as a communication cable or an electric cable is connected to the antenna main body 10 placed in the manhole 4. The cable 20 transmits and receives signals and supplies power to the antenna main body 10.

[0013] 3 is an external view showing an example of the configuration of a convex lens according to this embodiment. The convex lens 50 is hemispherical with a spherical side 50-1 that is a hemispherical surface and an aspherical side 50-2 that is a circular flat surface. The convex lens 50 is disposed on the sky side of the antenna body 10 inside the manhole 4. The spherical side 50-1 of the convex lens 50 faces the antenna body 10. The relative dielectric constant of the convex lens 50 is 9 to 11.

[0014] Fig. 4 is a diagram showing an example of the configuration of the antenna body 10 according to this embodiment, as viewed from above. Fig. 4 shows the arrangement on a horizontal plane (xy plane). In Fig. 4, the z-axis direction is the vertical direction.

[0015] The antenna body 10 includes six vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6), six horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6), and a circular shape 15.

[0016] The ground plane 100 is a flat conductor. The ground plane 100 is provided with the power feeders 12 (12-1, 12-2, 12-3, 12-4, 12-5, 12-6) of the vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6). The vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) are fed with power from the power feeders 12 (12-1, 12-2, 12-3, 12-4, 12-5, 12-6).

[0017] The ground plate 100 is provided with the power feed units 14 (14-1, 14-2, 14-3, 14-4, 14-5, 14-6) of the horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6). The horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) are disposed at a constant height from the ground plate 100. The horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) are fed with power from the power feed units 14 (14-1, 14-2, 14-3, 14-4, 14-5, 14-6) via feeder lines (not shown).

[0018] Six vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) are arranged at equal intervals on a first circumference. Vertically polarized monopole antenna 11-1 is arranged at 0 degrees, vertically polarized monopole antenna 11-2 is arranged at 60 degrees, vertically polarized monopole antenna 11-3 is arranged at 120 degrees, vertically polarized monopole antenna 11-4 is arranged at 180 degrees, vertically polarized monopole antenna 11-5 is arranged at 240 degrees, and vertically polarized monopole antenna 11-6 is arranged at 300 degrees.

[0019] The antenna body 10 configures a first array antenna (vertically polarized array antenna) with three vertically polarized monopole antennas 11-1, 11-3, 11-5 arranged at angles of 0 degrees, 120 degrees, and 240 degrees. The antenna body 10 configures a second array antenna (vertically polarized array antenna) with three vertically polarized monopole antennas 11-2, 11-4, 11-6 arranged at angles of 60 degrees, 180 degrees, and 300 degrees.

[0020] Six horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) are arranged at equal intervals on the second circumference. Horizontally polarized dipole antenna 13-1 is arranged at 30 degrees, horizontally polarized dipole antenna 13-2 is arranged at 90 degrees, horizontally polarized dipole antenna 13-3 is arranged at 150 degrees, horizontally polarized dipole antenna 13-4 is arranged at 210 degrees, horizontally polarized dipole antenna 13-5 is arranged at 270 degrees, and horizontally polarized dipole antenna 13-6 is arranged at 330 degrees.

[0021] The antenna body 10 configures a third array antenna (horizontally polarized array antenna) with three horizontally polarized dipole antennas 13-1, 13-3, 13-5 arranged at angles of 30 degrees, 150 degrees, and 270 degrees. The antenna body 10 configures a fourth array antenna (horizontally polarized array antenna) with three horizontally polarized dipole antennas 13-2, 13-4, 13-6 arranged at angles of 90 degrees, 210 degrees, and 330 degrees.

[0022] The first circumference on which the vertically polarized monopole antenna 11 is arranged and the second circumference on which the horizontally polarized dipole antenna 13 is arranged are concentric circles. The first circumference on which the vertically polarized monopole antenna 11 is arranged is located inside the second circumference on which the horizontally polarized dipole antenna 13 is arranged.

[0023] The circle 15 has a cylindrical shape and is disposed at the center of the first circumference and the second circumference.

[0024] Figures 5 and 6 are dimensional diagrams of the antenna body 10 according to this embodiment, with Figure 5 being a diagram seen from above and Figure 6 being a diagram seen from the side. Figure 5 shows the arrangement on a horizontal plane (xy plane). In Figure 5, the z-axis direction is the vertical direction. Figure 6 shows the arrangement on a vertical plane (xz plane).

[0025] Vertically polarized monopole antenna 11 is rod-shaped and has a length of H1. Horizontally polarized dipole antenna 13 has a total length of W1, and is fed from feeding point 14 to the midpoint of the total length. Horizontally polarized dipole antenna 13 is disposed at a height H2 from ground plate 100 by an insulator (not shown).

[0026] Vertically polarized monopole antenna 11 is positioned at a distance D1 from the center of the first circumference (the center of circle 15). Horizontally polarized dipole antenna 13 is positioned at a distance D2 from the center of the second circumference (the center of circle 15).

[0027] The circle 15 is cylindrical, the radius of the cylinder is R1, and the height of the cylinder is H3.

[0028] FIG. 7 is a dimensional diagram of the antenna device according to this embodiment. The convex lens 50 is The diameter of the circular plane of the aspherical side 50-2 is 2R50 (the radius is R50), and the length of the hemispherical surface of the spherical side 50-1 is H50a. The convex lens 50 is disposed at a height H50b from the bottom surface 4a of the manhole 4. The size of the convex lens 50 is preferably as large as possible while still being able to fit inside the manhole 4.

[0029] Next, the effects of the antenna device according to this embodiment will be described with reference to FIGS.

[0030] Figures 8 to 12 are diagrams showing simulation results of the antenna device according to this embodiment. The antenna body 10 used in the simulations shown in Figures 8 to 12 has dimensions in Figures 5 and 6 described above of "W1 = 18 millimeters (mm), D1 = 38 mm, D2 = 48 mm, H1 = 12 mm, H2 = 18 mm, H3 = 30 mm, R1 = 15 mm."

[0031] Moreover, the dimensions in FIG. 7 are "2R50 = 350 mm (R50 = 175 mm), H50a = 75 mm, H50b = 45 mm."

[0032] Fig. 8 is a graph showing the return loss characteristics of a first array antenna (vertically polarized array antenna) composed of vertically polarized monopole antennas 11-1, 11-3, and 11-5. Fig. 9 is a graph showing the return loss characteristics of a second array antenna (vertically polarized array antenna) composed of vertically polarized monopole antennas 11-2, 11-4, and 11-6.

[0033] FIG. 10 is a graph showing the return loss characteristics of the third array antenna constituted by horizontally polarized dipole antennas 13-1, 13-3, and 13-5. FIG. 11 is a graph showing the return loss characteristics of the fourth array antenna constituted by horizontally polarized dipole antennas 13-2, 13-4, and 13-6.

[0034] In Figures 8 to 11, the horizontal axis is frequency (unit: gigahertz (GHz)), and the vertical axis is return loss (unit: decibels (dB)).

[0035] As shown in the graphs in Figures 8 to 11, in the 4 GHz frequency band used, the return loss for vertical polarization was less than -10 dB, and the return loss for horizontal polarization was less than -10 dB, indicating that good results were obtained for both vertical and horizontal polarization.

[0036] Fig. 12 is a diagram showing a three-dimensional radio wave radiation pattern of the antenna device according to this embodiment. As shown in Fig. 12, the radio wave radiation pattern in the vertical plane can be directed toward the ground surface (xy plane direction) rather than toward the sky (positive direction of the z axis). This expands the directivity in the horizontal plane near the ground surface (xy plane, z axis is near the origin). Therefore, even if this antenna device is placed inside a manhole 4, the effect of expanding the wireless communication service area on the ground can be obtained.

[0037] Next, a modified example of the antenna device according to this embodiment will be described. Figures 13 and 14 are diagrams showing a modified example of the antenna device according to this embodiment. This modified example differs from the above-described antenna device in that, as in the convex lens 50a shown in Figure 13, a hemispherical recess 50a-3 is provided on the aspheric side 50a-2 of the convex lens 50a in the above-described convex lens 50. Other than this, it is the same as the above-described antenna device.

[0038] 14 is a dimensional diagram of the convex lens 50a in the modified example of the antenna device according to the present embodiment. The convex lens 50a has a circular flat surface (having a recess 50a-3) on the aspheric side 50-2 with a diameter of 2R50a (radius is R50a), and a hemispherical recess 50a-3 with a diameter of 2R50a-3 (radius is R50a-3). For example, when "2R50a=350 mm (R50a=175 mm)", "2R50a-3=94.5 mm (R50a-3=47.25 mm)" was obtained. It was confirmed by simulation that the above-mentioned effect could be obtained in this modified example as well.

[0039] As described above, according to this embodiment, the radio wave radiation pattern in the vertical plane of the antenna device can be directed toward the ground surface rather than the sky, and the directivity in the horizontal plane near the ground surface is expanded. This provides the effect of expanding the wireless communication service area on the ground, even if the antenna device is placed inside a manhole.

[0040] Moreover, according to this embodiment, a total of four array antennas are configured, including a first array antenna and a second array antenna using vertically polarized monopole antennas 11, and a third array antenna and a fourth array antenna using horizontally polarized dipole antennas 13. This makes it possible to perform four-branch MIMO (Multi Input Multi Output) communication.

[0041] In the above-described embodiment, the circle 15 is provided, but the circle 15 does not necessarily have to be provided.

[0042] Furthermore, in the above-described embodiment, the first circumference on which the vertically polarized monopole antenna 11 is arranged and the second circumference on which the horizontally polarized dipole antenna 13 is arranged are concentric circles, and the first circumference is located inside the second circumference, but the opposite may also be true, that is, the first circumference may be located outside the second circumference.

[0043] In addition, in the above-described embodiment, the antenna device is placed inside a manhole, but the underground space in which the antenna device is placed is not limited to a manhole, and the antenna device may be placed in an underground space other than a manhole.

[0044] This will, for example, make it possible to improve the overall service quality in wireless networks, thereby contributing to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0045] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0046] 1...manhole cover, 2...underground, 3...ground surface, 4...manhole, 10...antenna body, 50, 50a...convex lens, 50a-3...depression, 11...vertical polarized monopole antenna, 13...horizontal polarized dipole antenna, 12, 14...power supply part, 15...circular, 20...cable, 100...ground plate

Claims

1. An antenna device disposed in an underground space extending from the ground surface toward the underground, An antenna body including a vertically polarized array antenna and a horizontally polarized array antenna; a hemispherical convex lens; The convex lens is disposed on the sky side of the antenna body, The spherical side of the convex lens faces the antenna body. Antenna device.

2. A hemispherical recess is provided on the aspheric surface side of the convex lens.

2. The antenna device according to claim 1.

3. The antenna body includes: six vertically polarized monopole antennas equally spaced on a first circumference; six horizontally polarized dipole antennas equally spaced on a second circumference; A first array antenna is configured by three of the vertically polarized monopole antennas arranged at 0 degrees, 120 degrees and 240 degrees, a second array antenna is formed by three of the vertically polarized monopole antennas arranged at 60 degrees, 180 degrees and 300 degrees, a third array antenna is formed by three of the horizontally polarized dipole antennas arranged at 30 degrees, 150 degrees and 270 degrees, A fourth array antenna is constituted by three of the horizontally polarized dipole antennas arranged at 90 degrees, 210 degrees and 330 degrees.

3. An antenna device according to claim 1 or 2.

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