JP7640499B2 - Antenna Device - Google Patents

Description

The present invention relates to an antenna device.

Conventionally, there is known an antenna device that is installed in a manhole (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's surface when installed underground and that houses the antenna element and the installation stand, and a lid made of FRP (Fiber Reinforced Plastics) that 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.

JP 2021-177632 A

However, in the conventional antenna devices described above, although adjustments can be made to satisfy the radio wave protection guidelines by adjusting the distance from the antenna element to the manhole cover, this does not take into account the antenna directivity, and is therefore insufficient for expanding the wireless communication service area on the ground.

The present invention was made in consideration of these circumstances, and its purpose is to expand the above-ground wireless communication service area of an antenna device placed in an underground space such as a manhole.

One aspect of the present invention is an antenna device that is placed in an underground space extending from the ground surface toward the ground, and includes 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, where 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.

One aspect of the present invention is an antenna device that is placed in an underground space extending from the ground surface toward the ground, and includes six vertically polarized monopole antennas that are equally spaced on a circumference, with three of the vertically polarized monopole antennas arranged at angles of 0 degrees, 120 degrees, and 240 degrees forming a first array antenna, and three of the vertically polarized monopole antennas arranged at angles of 60 degrees, 180 degrees, and 300 degrees forming a second array antenna.

One aspect of the present invention is an antenna device that is placed in an underground space extending from the ground surface toward the ground, and that includes six horizontally polarized dipole antennas that are equally spaced on a circumference, with three of the horizontally polarized dipole antennas arranged at 30 degrees, 150 degrees, and 270 degrees forming a first array antenna, and three of the horizontally polarized dipole antennas arranged at 90 degrees, 210 degrees, and 330 degrees forming a second array antenna.

In one aspect of the present invention, the antenna device further includes a cylindrical circle that is positioned at the center of the circumference.

The present invention has the effect of expanding the wireless communication service area on the ground of an antenna device placed in an underground space such as a manhole.

FIG. 2 is an explanatory diagram for explaining an example of arrangement of an antenna device according to an embodiment. FIG. 2 is an explanatory diagram for explaining an example of arrangement of an antenna device according to an embodiment. 1 is a diagram illustrating a configuration example of an antenna device according to an embodiment; FIG. 2 is a dimensional diagram of an antenna device according to an embodiment. FIG. 2 is a dimensional diagram of an antenna device according to an embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment. 11A and 11B are diagrams illustrating simulation results of the antenna device according to the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 and 2 are explanatory diagrams for explaining an example of the arrangement of an antenna device 10 according to an embodiment, where FIG. 1 is a diagram seen from a side and FIG. 2 is a diagram seen from above.

The antenna device 10 is placed in 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 cover that covers the manhole 4.

The material of the manhole cover 1 is preferably a material that does not affect the radio wave propagation of the antenna device 10 placed in the manhole 4. The material of the manhole cover 1 is, for example, FRP (Fiber Reinforced Plastics).

A cable 20, such as a communication cable or an electric cable, is connected to the antenna device 10 placed in the manhole 4. The antenna device 10 transmits and receives signals and is powered by the cable 20.

Figure 3 is a diagram showing an example of the configuration of an antenna device 10 according to this embodiment, as viewed from above. Figure 3 shows the arrangement in a horizontal plane (x-y plane). In Figure 3, the z-axis direction is the vertical direction.

The antenna device 10 comprises 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.

The ground plane 100 is a flat conductor. The ground plane 100 is provided with the power feed sections 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). Each vertically polarized monopole antenna 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) is fed with power from each of the power feed sections 12 (12-1, 12-2, 12-3, 12-4, 12-5, 12-6).

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). Each horizontally polarized dipole antenna 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) is disposed at a fixed height from the ground plate 100. Each horizontally polarized dipole antenna 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) is fed with power from each power feed unit 14 (14-1, 14-2, 14-3, 14-4, 14-5, 14-6) via a feeder (not shown).

Six vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) are arranged at equal intervals on the 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.

The antenna device 10 forms a first array antenna with three vertically polarized monopole antennas 11-1, 11-3, and 11-5 arranged at angles of 0 degrees, 120 degrees, and 240 degrees. The antenna device 10 forms a second array antenna with three vertically polarized monopole antennas 11-2, 11-4, and 11-6 arranged at angles of 60 degrees, 180 degrees, and 300 degrees.

The 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. The horizontally polarized dipole antenna 13-1 is arranged at 30 degrees, the horizontally polarized dipole antenna 13-2 is arranged at 90 degrees, the horizontally polarized dipole antenna 13-3 is arranged at 150 degrees, the horizontally polarized dipole antenna 13-4 is arranged at 210 degrees, the horizontally polarized dipole antenna 13-5 is arranged at 270 degrees, and the horizontally polarized dipole antenna 13-6 is arranged at 330 degrees.

The antenna device 10 forms a third array antenna with three horizontally polarized dipole antennas 13-1, 13-3, and 13-5 arranged at 30 degrees, 150 degrees, and 270 degrees. The antenna device 10 forms a fourth array antenna with three horizontally polarized dipole antennas 13-2, 13-4, and 13-6 arranged at 90 degrees, 210 degrees, and 330 degrees.

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 inside the second circumference on which the horizontally polarized dipole antenna 13 is arranged.

Circle 15 is cylindrical. Circle 15 is located at the center of the first circumference and the second circumference.

Figures 4 and 5 are dimensional diagrams of the antenna device 10 according to this embodiment, with Figure 4 being a view from above and Figure 5 being a view from the side. Figure 4 shows the arrangement in a horizontal plane (x-y plane). In Figure 4, the z-axis direction is the vertical direction. Figure 5 shows the arrangement in a vertical plane (x-z plane).

The vertically polarized monopole antenna 11 is rod-shaped and has a length of H1. The horizontally polarized dipole antenna 13 has a total length of W1, and is fed from the power feeder 14 to the midpoint of the total length. The horizontally polarized dipole antenna 13 is positioned at a height H2 from the base plate 100 by an insulator (not shown).

The vertically polarized monopole antenna 11 is positioned at a distance D1 from the center of the first circumference (the center of the circle 15). The horizontally polarized dipole antenna 13 is positioned at a distance D2 from the center of the second circumference (the center of the circle 15).

Circle 15 is cylindrical, the radius of the cylinder is R1, and the height of the cylinder is H3.

Next, the effects of the antenna device 10 according to this embodiment will be explained with reference to Figures 6 to 15.

Figures 6 to 15 are diagrams showing simulation results of the antenna device 10 according to this embodiment. The antenna device 10 used in the simulations shown in Figures 6 to 15 has the following dimensions in Figures 4 and 5: W1 = 36 millimeters (mm), D1 = 38 mm, D2 = 48 mm, H1 = 17 mm, H2 = 26 mm, H3 = 30 mm, R1 = 15 mm.

Figure 6 is a graph showing the return loss characteristics of the first and second array antennas, which are composed of a vertically polarized monopole antenna 11. Figure 7 is a graph showing the return loss characteristics of the third and fourth array antennas, which are composed of a horizontally polarized dipole antenna 13. In Figures 6 and 7, the horizontal axis is frequency (unit: gigahertz (GHz)), and the vertical axis is return loss (unit: decibels (dB)).

As shown in the graphs in Figures 6 and 7, in the 3.5 GHz band, which is the frequency band used, the return loss for vertical polarization is less than -7 dB, and the return loss for horizontal polarization is less than -9 dB, and good results are obtained for both vertical and horizontal polarization.

Figures 8 to 11 are diagrams showing the radio wave radiation patterns of the first and second array antennas, which are composed of a vertically polarized monopole antenna 11. Figures 12 to 15 are diagrams showing the radio wave radiation patterns of the third and fourth array antennas, which are composed of a horizontally polarized dipole antenna 13. The frequency band used in the simulation of the radio wave radiation patterns in Figures 8 to 15 is the 3.5 GHz band.

Figure 8 shows the radio wave radiation pattern in the vertical plane of the first array antenna composed of a vertically polarized monopole antenna 11. As shown in the radio wave radiation pattern in the vertical plane of Figure 8, the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction). A null is formed in the sky direction (z-axis direction). Because the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction), the effect of expanding the wireless communication service area on the ground can be obtained even if the antenna device 10 is placed in a manhole 4.

Figure 9 shows the radio wave radiation pattern in the vertical plane of the second array antenna composed of a vertically polarized monopole antenna 11. As shown in the radio wave radiation pattern in the vertical plane of Figure 9, the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction). A null is formed in the sky direction (z-axis direction). Because the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction), the effect of expanding the wireless communication service area on the ground can be obtained even if the antenna device 10 is placed in a manhole 4.

Figure 10 shows the radio wave radiation pattern in the horizontal plane of the first array antenna composed of the vertically polarized monopole antenna 11. As shown in the radio wave radiation pattern in the horizontal plane of Figure 10, good radiation intensity is obtained in almost all directions.

Figure 11 shows the radio wave radiation pattern in the horizontal plane of the second array antenna, which is composed of a vertically polarized monopole antenna 11. As shown in the radio wave radiation pattern in the horizontal plane of Figure 11, good radiation intensity is obtained in almost all directions.

Figure 12 shows the radio wave radiation pattern in the vertical plane of the third array antenna composed of a horizontally polarized dipole antenna 13. As shown in the radio wave radiation pattern in the vertical plane of Figure 12, the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction). A null is formed in the sky (z-axis direction). Because the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction), the effect of expanding the wireless communication service area on the ground can be obtained even if the antenna device 10 is placed in a manhole 4.

Figure 13 shows the radio wave radiation pattern in the vertical plane of the fourth array antenna composed of a horizontally polarized dipole antenna 13. As shown in the radio wave radiation pattern in the vertical plane of Figure 13, the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction). A null is formed in the sky (z-axis direction). Because the main lobe is oriented more toward the ground surface (x-axis direction) than toward the sky (z-axis direction), the effect of expanding the wireless communication service area on the ground can be obtained even if the antenna device 10 is placed in a manhole 4.

Figure 14 shows the radio wave radiation pattern in the horizontal plane of the third array antenna, which is composed of the horizontally polarized dipole antenna 13. As shown in the radio wave radiation pattern in the horizontal plane of Figure 14, good radiation intensity is obtained in almost all directions.

Figure 15 shows the radio wave radiation pattern in the horizontal plane of the fourth array antenna, which is composed of a horizontally polarized dipole antenna 13. As shown in the radio wave radiation pattern in the horizontal plane of Figure 15, good radiation intensity is obtained in almost all directions.

As described above, according to this embodiment, the radio wave radiation pattern in the vertical plane of the antenna device 10 can be directed toward the ground surface rather than toward the sky. This has the effect of expanding the wireless communication service area on the ground of the antenna device 10 placed in the manhole 4.

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

In the above embodiment, both a vertically polarized monopole antenna 11 and a horizontally polarized dipole antenna 13 are used, but this is not limited to this.

For example, in FIG. 3, the six horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6) may be removed, and only the first and second array antennas may be configured using the six vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6).

For example, in FIG. 3, the six vertically polarized monopole antennas 11 (11-1, 11-2, 11-3, 11-4, 11-5, 11-6) may be removed, and only the first and second array antennas may be configured using the six horizontally polarized dipole antennas 13 (13-1, 13-2, 13-3, 13-4, 13-5, 13-6).

In addition, in the above-described embodiment, a circle 15 is provided, but the circle 15 does not have to be provided.

In addition, 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.

In addition, in the above-described embodiment, the antenna device 10 is placed in the manhole 4, but the underground space in which the antenna device 10 is placed is not limited to the manhole 4, and the antenna device 10 may be placed in an underground space other than the manhole 4.

As a result, it will be possible to improve the overall service quality in wireless networks, for example, and contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment and includes design modifications and the like that do not deviate from the gist of the present invention.

1...manhole cover, 2...underground, 3...ground surface, 4...manhole, 10...antenna device, 11...vertically polarized monopole antenna, 13...horizontally polarized dipole antenna, 12, 14...power supply, 15...circular, 20...cable, 100...ground plate

Claims (2)

An antenna device disposed in an underground space extending from the ground surface toward the underground,
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.
Antenna device. Further comprising a cylindrical circle disposed at a central portion of the circumference.
2. The antenna device according to claim 1.

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