Antenna set

Abstract

An antenna set according to the present invention, comprising an antenna unit group for transmitting a stream by distributed-MIMO, the antenna unit group including a plurality of antenna units spaced apart from each other, wherein the antenna units are installed with a height of 3 m to 8 m inclusive, the non-directional angle in the horizontal plane of a radiation pattern is greater than or equal to 180 degrees, and the radiation peak of a main lobe is angled at a depression angle greater than 0 degrees and not greater than 15 degrees.

Description

[Technical field]

[0001] The present disclosure relates to an antenna set. [Background technology]

[0002] Conventionally, there has been known a MIMO (Multiple Input Multiple Output) type wireless communication using multiple antenna elements (see, for example, Patent Documents 1 and 2). In addition, distributed MIMO is known as a technique for MIMO multiplexing and transmitting different streams from multiple transmission locations (see, for example, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 135368 [Patent Document 2] JP 2017-38195 A [Non-patent literature]

[0004] [Non-Patent Document 1] NTT DOCOMO Technical Journal Vol.25 No.1 (Apr.2017) Summary of the Invention [Problem to be solved by the invention]

[0005] However, distributed MIMO requires that multiple antenna units that transmit streams be installed at a certain distance from each other, making it difficult to secure an installation location that can form a communication area that can obtain a relatively high throughput.

[0006] The present disclosure provides an antenna set capable of forming a communication area that provides a relatively high throughput. [Means for solving the problem]

[0007] The present disclosure relates to An antenna set including a group of antenna units for transmitting streams in distributed MIMO, The antenna unit group includes a plurality of antenna units arranged apart from each other, The antenna set includes a plurality of antenna units installed at a height of 3 m or more and 8 m or less, a radiation pattern having an omnidirectional angle of 180 degrees or more in the horizontal plane, and a main lobe radiation peak tilted at a depression angle of more than 0 degrees and not more than 15 degrees. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide an antenna set capable of forming a communication area that provides a relatively high throughput. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of the arrangement of an antenna set including a group of antenna units transmitting streams in distributed MIMO. [Diagram 2] 1 is a diagram showing an example of a 360-degree omnidirectional radiation pattern radiated from one antenna unit. FIG. [Diagram 3] 13 is a graph showing an example of the results of measuring the reception levels at three receiving antennas A1, A2, and A3 at a reception point R when radio waves are transmitted from one of three antenna units located at different distances from the reception point R. [Figure 4] 1 is a diagram showing an example of a case where radio waves are received at a reception point R when the gain of the radiation peak of the main lobe is relatively low. [Diagram 5] 1 is a diagram showing an example of a case where radio waves are received at a reception point R when the gain of the radiation peak of the main lobe is relatively high. [Figure 6] 1 is a diagram showing an example of a delay profile of a direct wave and a reflected wave received by a receiving antenna located at a receiving point R. FIG. [Figure 7]1 is a diagram showing an example of the relationship between the half-width of a main lobe in a vertical plane and the gain of the radiation peak of the main lobe. FIG. [Figure 8] This is a list of throughput evaluation values ​​measured when transmitting and receiving radio waves using 3x3 MIMO. [Figure 9] FIG. 13 is a diagram showing cumulative contribution rates in principal component analysis. [Figure 10] This is a scatter plot of the principal component scores obtained by substituting 19 types of individual data into the first principal component PC1 and the second principal component PC2. [Figure 11] This is a scatter plot of the principal component scores obtained by substituting 19 types of individual data into the first principal component PC1 and the second principal component PC2. [Figure 12] FIG. 2 is a diagram showing a schematic plan view of a square area formed around two adjacent antenna units. [Figure 13] 1 is a cross-sectional view showing an example of an antenna unit installed on the outer peripheral surface of a pole. [Figure 14] FIG. 13 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) at an azimuth angle of 0° and in the XY plane when radiating a beam of 11 dBi at a tilt angle of 5° relative to the XY plane. [Figure 15] FIG. 13 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) at an azimuth angle of 0° and in the XY plane when radiating a beam of 11 dBi at a tilt angle of 10° with respect to the XY plane. [Figure 16] FIG. 13 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) at an azimuth angle of 0° and in the XY plane when radiating a beam of 14 dBi at a tilt angle of 10° relative to the XY plane. [Figure 17] FIG. 15 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics shown in FIG. 14 are arranged at intervals of 20 m. [Figure 18] FIG. 16 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics shown in FIG. 15 are arranged at intervals of 20 m. [Figure 19]FIG. 17 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics shown in FIG. 16 are arranged at intervals of 20 m. [Figure 20] FIG. 15 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics shown in FIG. 14 are concentrated in the same place. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described with reference to the drawings. For ease of understanding, the scale of each part in the drawings may differ from the actual scale. In this specification, a three-dimensional orthogonal coordinate system with three axial directions (X-axis, Y-axis, and Z-axis) is used.

[0011] The X-axis, Y-axis, and Z-axis directions respectively represent directions parallel to the X-axis, Y-axis, and Z-axis. The X-axis, Y-axis, and Z-axis directions are perpendicular to each other. The XY plane, YZ plane, and ZX plane respectively represent imaginary planes parallel to the X-axis and Y-axis directions, imaginary planes parallel to the Y-axis and Z-axis directions, and imaginary planes parallel to the Z-axis and X-axis directions.

[0012] FIG. 1 is a diagram showing an example of the arrangement of an antenna set including a group of antenna units that transmit streams in distributed MIMO. The X-axis direction and the Y-axis direction are approximately parallel to a direction parallel to a horizontal plane (horizontal direction), and the Z-axis direction is approximately parallel to a vertical direction perpendicular to the horizontal plane. The antenna set 10 shown in FIG. 1 includes an antenna unit group including a plurality of antenna units arranged apart from each other, and FIG. 1 shows three antenna units (a first antenna unit 11, a second antenna unit 12, and a third antenna unit 13) as an example. Hereinafter, the first antenna unit 11, the second antenna unit 12, and the third antenna unit 13 are also collectively referred to as antenna units 11, 12, and 13.

[0013] The antenna units 11, 12, and 13 are devices that transmit and receive radio waves in a high frequency band (for example, 0.3 GHz to 300 GHz) such as microwaves including millimeter waves. The antenna units 11, 12, and 13 are formed to be capable of transmitting and receiving radio waves corresponding to wireless communication standards such as the fifth generation mobile communication system (so-called 5G), Bluetooth (registered trademark), and wireless LAN (Local Area Network) standards such as IEEE802.11ac. The antenna units 11, 12, and 13 may be formed to be capable of transmitting and receiving electromagnetic waves corresponding to standards other than these, or may be formed to be capable of transmitting and receiving electromagnetic waves of a plurality of different frequencies. Each of the antenna units 11, 12, and 13, or the antenna set 10 including the antenna units 11, 12, and 13, can be used, for example, as a wireless base station.

[0014] The antenna set 10 includes a group of antenna units (antenna units 11, 12, and 13 in this example) that transmit streams by distributed MIMO. In distributed MIMO, it is required that the multiple antenna units that transmit streams are installed at a certain distance from each other. Therefore, it is difficult to secure an installation location that can form a communication area (also called a "coverage area") that can obtain a relatively high throughput. Radio waves in high frequency bands such as microwaves (especially millimeter waves) are difficult to propagate long distances and have a strong tendency to travel in a straight line, so it is not easy to design a communication area and there is a possibility that a huge number of wireless base stations will be required.

[0015] In the antenna set 10 illustrated in Fig. 1, the antenna units 11, 12, and 13, which are arranged apart from each other, are all installed at a height in the Z-axis direction from the ground of 3 m to 8 m, and the radiation peak of the main lobe is inclined at a depression angle of more than 0 degrees and not more than 15 degrees. As a result, the antenna set 10 can transmit beams toward the ground from each of the antenna units 11, 12, and 13 installed at a relatively high location, so that a communication area that can obtain a relatively high throughput can be formed between the antenna units and the ground. The depression angle of the radiation peak of the main lobe is preferably an angle in a vertical plane that is perpendicular to the horizontal plane and perpendicular to the direction in which the antenna units 11, 12, and 13 are arranged.

[0016] When the antenna unit is installed at a height of 3m or more, the antenna unit is farther from the ground than when it is installed at a height of less than 3m, making it easier to expand the communication area in the horizontal direction where a relatively high throughput can be obtained. When the antenna unit is installed at a height of 8m or less, the antenna unit is closer to the ground than when it is installed at a height of more than 8m, making it possible to ensure a relatively high gain even at a location that is relatively low above the ground. This makes it easier to expand the communication area in which a relatively high throughput can be obtained.

[0017] It is more preferable that the multiple antenna units are installed at a distance of 3.5 m to 7.5 m from the ground, in order to form a communication area between the antenna units and the ground that can provide a relatively high throughput.

[0018] The height at which an antenna unit is installed is defined as the height from a reference plane (for example, the ground or floor surface, or it may be a virtual surface) parallel to the horizontal plane. For example, when an antenna unit that radiates radio waves outdoors is installed outdoors as shown in Fig. 1, the installation height of the antenna unit is defined as the height from the outdoor ground. For example, when an antenna unit that radiates radio waves indoors is installed indoors, the installation height of the antenna unit is defined as the height from the indoor floor.

[0019] When the main lobe radiation peak is tilted at a depression angle greater than 0 degrees, the main lobe is closer to the ground than when the main lobe radiation peak is tilted at an elevation angle. This makes it possible to ensure a relatively high gain even at a relatively low height from the ground, making it easier to expand the communication area where a relatively high throughput can be obtained. On the other hand, when the main lobe radiation peak is tilted at a depression angle of 15 degrees or less, the range where the main lobe reaches the ground is farther away from the installation point of the antenna unit than when the main lobe radiation peak is tilted at a depression angle of more than 15 degrees. This makes it easier to expand the communication area where a relatively high throughput can be obtained in the horizontal direction.

[0020] It is more preferable that the radiation peak of the main lobe is inclined at a depression angle of 1.0 degrees or more and 14 degrees or less, in order to form a communication area between the ground and the radiation peak, in which a relatively high throughput can be obtained.

[0021] 1, the antenna units 11, 12, and 13 are arranged at a distance from each other in the horizontal direction. This makes it easy for the antenna set 10 to expand in the horizontal direction a communication area where a relatively high throughput can be obtained. An example of a configuration in which the antenna units 11, 12, and 13 are arranged at a distance from each other in the horizontal direction is a configuration in which the antenna units 11, 12, and 13 are all arranged to intersect with a virtual plane parallel to the horizontal plane.

[0022] For example, the antenna units 11, 12, and 13 are arranged at the same height. This makes it easy to overlap a communication area formed by a beam transmitted from the first antenna unit 11 toward the ground, a communication area formed by a beam transmitted from the second antenna unit 12 toward the ground, and a communication area formed by a beam transmitted from the third antenna unit 13 toward the ground. Therefore, the antenna set 10 can form a communication area that can obtain a relatively high throughput. An example of a form in which the antenna units 11, 12, and 13 are arranged at the same height is a form in which the distances (heights) from a reference plane parallel to the horizontal plane to the centers (centers of gravity) of the antenna apertures of the antenna units 11, 12, and 13 are equal to each other.

[0023] Among the antenna units 11, 12, and 13, one or more partial antenna units may be arranged at a different height from one or more remaining antenna units. An example of a form in which one or more partial antenna units are arranged at a different height from one or more remaining antenna units is a form in which the distance (height) from a reference plane parallel to the horizontal plane to the center (center of gravity) of the antenna aperture is different between one or more partial antenna units and one or more remaining antenna units.

[0024] 1, the antenna units 11, 12, and 13 are installed on structures such as columnar poles 1, 2, and 3 that are installed at a distance from each other. By installing the antenna units 11, 12, and 13 on a plurality of structures that are installed at a distance from each other, it becomes easy to arrange the antenna units 11, 12, and 13 at intervals required for distributed MIMO.

[0025] In addition, among the antenna units 11, 12, and 13, one or more of the antenna units may be installed in a structure in which one or more of the remaining antenna units are installed, as long as the interval required for distributed MIMO can be ensured. This allows one or more of the antenna units and one or more of the remaining antenna units to be installed in a common structure, making it easier to install each antenna unit.

[0026] Each of the antenna units 11, 12, and 13 is connected to, for example, a wiring (not shown). Specific examples of the wiring include a coaxial cable and an optical cable. The antenna units 11, 12, and 13 are connected to a common baseband unit (not shown) via the corresponding wiring. The baseband unit is a device that performs communication control for implementing distributed MIMO. The baseband unit may be installed in a structure in which any of the antenna units 11, 12, and 13 is installed, or may be installed in a location such as a building, the ground, or a floor surface.

[0027] In the example shown in Fig. 1, the antenna units 11, 12, and 13 are arranged parallel to each other. This makes it easy to overlap a communication area formed by a beam transmitted from the first antenna unit 11 toward the ground, a communication area formed by a beam transmitted from the second antenna unit 12 toward the ground, and a communication area formed by a beam transmitted from the third antenna unit 13 toward the ground. Therefore, the antenna set 10 can form a communication area in which a relatively high throughput can be obtained. In the example shown in Fig. 1, in particular, the antenna units 11, 12, and 13 are arranged along a common ZX plane (in this example, a virtual plane perpendicular to the horizontal plane), so that a communication area in which a relatively high throughput can be obtained can be more easily formed.

[0028] The interval d between the multiple antenna units is, for example, 10 m or more and 80 m or less in order to ensure throughput while preventing the installation of the multiple antenna units from becoming too wide. When the interval d is 10 m or more, it is easier to expand the communication area where a relatively high throughput can be obtained in the direction of the interval d compared to when the interval d is less than 10 m. When the interval d is 80 m or less, it is possible to narrow the installation area of ​​the multiple antenna units compared to when the interval d is more than 80 m. Also, when the interval d is 80 m or less, the overlapping area of ​​each communication area formed by each of the multiple antenna units is wider compared to when the interval d is more than 80 m, so it is easier to form a communication area where a relatively high throughput can be obtained. It is more preferable that the interval d is 20 m or more and 70 m or less in order to ensure throughput while preventing the installation of the multiple antenna units from becoming too wide.

[0029] The antenna set 10 may also include a reflector between adjacent antenna units included in the plurality of antenna units to reflect radio waves. The reflector makes it easier to form a communication area in which a relatively high throughput can be obtained. The reflector reflects radio waves in the direction of the communication area formed by the adjacent antenna units.

[0030] 1 is a top view (plan view) that shows an example of the positional relationship between an antenna set and a group of buildings from an above perspective (plan view). Buildings 41, 42, 43, 44, 45, 46, 47, and 48 are built along a road 50. Buildings 41, 42, 43, and 44 face buildings 45, 46, 47, and 48, respectively, across the road 50. Intersection 51 is a location where road 50 extending in the X-axis direction intersects with road 52 extending in the Y-axis direction. Antenna units 11, 12, and 13 are installed on poles 1, 2, and 3 that are aligned in the X-axis direction along road 50.

[0031] The antenna units 11, 12, and 13 have a radiation pattern with an omnidirectional angle of 180 degrees or more in the horizontal plane (the horizontal plane at the installation height of the antenna units 11, 12, and 13). As a result, even if one or more obstacles that impede radio wave propagation are present around the antenna units 11, 12, and 13, the antenna set 10 can form a communication area between the antenna units 11, 12, and 13 and the ground, where a relatively high throughput can be obtained. An obstacle (blocking object) that impedes radio wave propagation is, for example, a concrete structure such as a building.

[0032] FIG. 2 is a diagram showing an example of a radiation pattern in which the omnidirectional angle emitted from one antenna unit is 360 degrees. The omnidirectional angle in the horizontal plane of the radiation pattern refers to an angle range in which the deviation of the arithmetic mean value of the gain at each angle included in the range of ±15 degrees centered on each angle in the horizontal plane is 6 dB or less. For example, the arithmetic mean value of the gain at each of 31 angles included in the range of ±15 degrees centered on 0 degrees (345 degrees to 15 degrees) is plotted above 0 degrees, and the arithmetic mean value of the gain at each of 31 angles included in the range of ±15 degrees centered on 1 degree (346 degrees to 16 degrees) is plotted above 1 degree. Then, among the 360 ​​plotted values, a continuous angle range in which the deviation is 6 dB or less is defined as the omnidirectional angle. If there are multiple such ranges, the omnidirectional angle is the largest angle range. If the deviation is 6 dB or less over the entire circumference (all 360 points), it is also called "the directivity of the radiation pattern in the horizontal plane is 360 degrees omnidirectional."

[0033] When the half-width (also called "half-width angle") of the main lobe whose radiation peak is inclined at the above-mentioned depression angle of each of the antenna units 11, 12, and 13 is 6 degrees or more and 15 degrees or less, the antenna set 10 can form a communication area between the antenna set 10 and the ground, where a relatively high throughput can be obtained. This point will be described with reference to Figs. 1, 3, 4, and 5. The half-width of the main lobe is the opening angle at the point where the gain is 3 dB lower than the radiation peak of the main lobe (the part with the highest gain). The half-width of the main lobe whose radiation peak is inclined at the above-mentioned depression angle is preferably the angle of the main lobe in a vertical plane perpendicular to the horizontal plane and perpendicular to the direction in which the antenna units 11, 12, and 13 are arranged.

[0034] FIG. 3 is a graph showing an example of the results of measuring the reception levels at three receiving antennas A1, A2, and A3 at the reception point R when radio waves are transmitted from one of three antenna units 11, 12, and 13 at different distances from the reception point R. FIG. 3 shows two cases where the gain of the main lobe radiation peak is 14 dBi and 11 dBi. A gain of 11 dBi corresponds to a half-width of 10°, and a gain of 14 dBi corresponds to a half-width of 5°. The reception level on the vertical axis corresponds to "received power ÷ transmitted power." The reception point R is located at a position where the direct wave of the main lobe radiated from the third antenna unit 13 arrives, and the third antenna unit 13 is the closest to the reception point R among the three antenna units 11, 12, and 13 (see FIG. 1).

[0035] In the case of the third antenna unit 13 which is closest to the reception point R, the direct wave of the main lobe reaches the reception point R, so as shown in Fig. 3, the reception level at the reception point R is higher with a gain of 14 dBi than with a gain of 11 dBi. In contrast, in the case of the first antenna unit 11 and the second antenna unit 12 which are far from the reception point R, as shown in Fig. 3, the reception level at the reception point R is higher with a gain of 11 dBi than with a gain of 14 dBi. This is because the half-width of the main lobe is wider with a gain of 11 dBi than with a gain of 14 dBi, so that more reflected waves reach the reception point R.

[0036] FIG. 4 is a diagram showing an example of a case where radio waves are received at a reception point R when the gain of the radiation peak of the main lobe is relatively low. FIG. 5 is a diagram showing an example of a case where radio waves are received at a reception point R when the gain of the radiation peak of the main lobe is relatively high. In the case of FIG. 4 where the gain of the radiation peak is low, the half-width θ of the main lobe HP Therefore, the frequency at which radio waves reflected by obstacles such as buildings 42 reach the receiving point R increases, and the frequency at which incoming waves with relatively high gain reach the receiving point R increases. On the other hand, in the case of FIG. 5 where the gain of the radiation peak is high, the half-width θ HP Therefore, the degree to which radio waves reflected by obstacles such as buildings 42 reach the receiving point R is reduced, and the degree to which incoming waves with a relatively high gain reach the receiving point R is reduced.

[0037] Therefore, the antenna units 11, 12, and 13 each have a main lobe half-width θ HP If θ is more than 6 degrees, HP In comparison with the case where the half-width θ HP When the angle θ is 6 degrees or more, a communication area with a relatively high throughput can be formed between the ground and the antenna unit. HP If is less than 15 degrees, then θ HP Compared to when the half-width θ is greater than 15 degrees, the number of reflected waves that reach the receiving point R is reduced, but the degree to which a direct wave with a relatively high gain reaches the receiving point R increases. HP If the angle is 15 degrees or less, a communication area with a relatively high throughput can be formed between the antenna and the ground.

[0038] Also, the point where the level of the direct wave of the radio wave transmitted from one antenna unit included in the antenna unit group is the maximum is defined as reception point R, and the reception level Lp at this reception point R is defined as "the level [dB] of the reflected wave of the radio wave ÷ the level [dB] of the direct wave of the radio wave." The level of the reflected wave of the radio wave received at reception point R corresponds to "the received power of the reflected wave at reception point R ÷ the transmitted power of the radio wave," and the level of the direct wave of the radio wave received at reception point R corresponds to "the received power of the direct wave at reception point R ÷ the transmitted power of the radio wave." In this case, when the reception level Lp is 0.7 or more and 0.95 or less, preferably 0.75 or more and 0.99 or less, a communication area with a relatively high throughput can be formed between the ground.

[0039] Fig. 6 is a diagram showing an example of delay profiles of direct waves and reflected waves received by a receiving antenna A1 located at a receiving point R. Fig. 6 shows a case where radio waves are transmitted from a third antenna unit 13 installed on a pole 3 closest to the receiving point R, and a case where radio waves are transmitted from a first antenna unit 11 installed on a pole 1 farthest from the receiving point R. A communication area with a relatively high throughput can be formed between the receiving level Lp of 11 dBi, which satisfies the requirements of 0.7 to 0.95, compared to a case where the receiving level Lp is 14 dBi, which does not satisfy the requirements of 0.7 to 0.95.

[0040] FIG. 7 shows the half-width φ of the main lobe in the horizontal plane of the antennas A1, A2, A3, and A4 in FIG. HP The half-width θ of the main lobe in the vertical plane perpendicular to the horizontal plane when the angle is 100°, 80°, and 60°. HP 1 is a diagram showing an example of the relationship between the directional gain e [dBi] of the radiation peak of the main lobe and e=10×log 10 (41253 / (φ HP ×θ HP )) The following simple relational expression holds: The graph in Figure 7 shows the data obtained from this relational expression.

[0041] Main lobe half-width in the horizontal plane φ HP is not limited to 100°, 80°, or 60°, and may be larger or smaller than these. It is preferable that the antennas A1, A2, A3, and A4 are designed to have a directional gain close to e [dBi] shown in Fig. 7. The configuration of the antennas A1, A2, A3, and A4 will be described in detail later.

[0042] According to FIG. 7, the antennas A1, A2, A3, and A4 have a main lobe half-width φ HP When the angle is 100°, 80°, and 60°, the half-width θ of the main lobe in the vertical plane perpendicular to the horizontal plane is HP It is preferable to design the gain c to be close to 14 dBi to 21 dBi when the angle is between 6 degrees and 15 degrees. This makes it possible to increase the gain of one antenna unit. In this case, the antenna set 10 can form a communication area between itself and the ground, which can provide a relatively high throughput.

[0043] Figure 8 is a list of evaluation values ​​of throughput measured when radio waves are transmitted and received with 3x3 MIMO in a 60m x 200m area including the installation points of the three antenna units 11, 12, and 13 shown in Figure 1. The throughput is evaluated based on the values ​​measured when receiving points (assuming one receiving terminal) are placed in a 1m mesh in the area and the three receiving antennas located at each receiving point receive the streams transmitted from the three antenna units 11, 12, and 13.

[0044] Figure 8 shows the evaluation values ​​of throughput measured under 19 different conditions with different depression angles a (tilt angle), b, half-width c, and interval d. The depression angle a represents the average depression angle of each of the multiple antenna units. The height b represents the average installation height of each of the multiple antenna units. The half-width c represents the half-width θ of the main lobe radiated from each of the multiple antenna units. HP The distance d represents the average distance between adjacent antenna units included in the plurality of antenna units.

[0045] "Percentage of 1 Gbps or more" refers to the percentage (cumulative probability) of reception points where a throughput of 1 Gbps or more was measured among all reception points arranged in a 1 m mesh in a 60 m x 200 m area. "Percentage of 2 Gbps or more" refers to the percentage (cumulative probability) of reception points where a throughput of 2 Gbps or more was measured among all reception points arranged in a 1 m mesh in a 60 m x 200 m area. "Percentage of 3 Gbps or more" refers to the percentage (cumulative probability) of reception points where a throughput of 3 Gbps or more was measured among all reception points arranged in a 1 m mesh in a 60 m x 200 m area.

[0046] Using the measurement data group including the 19 data shown in FIG. 8, a principal component analysis was performed with four explanatory variables: the depression angle a (tilt angle), the height b, the half-width c, and the interval d. The first principal component PC1 and the second principal component PC2 were as follows: PC1=-(a / 10.6)-(b / 10.8)+(c / 5.7)+(d / 19.8)-1.8 PC2=(a / 12.0)+(b / 2.5)+(c / 6.6)+(d / 99.6)-4.9 The cumulative contribution rate of the first principal component PC1 and the second principal component PC2 is 69.1% (see FIG. 9).

[0047] Fig. 10 is a scatter plot of principal component scores obtained by substituting the above 19 types of individual data into the first principal component PC1 and the second principal component PC2. In Fig. 10, the "◯" marks represent principal component scores where the ratio of reception points where a throughput of 2 Gbps or more is measured is 60% or more among all reception points arranged in a 1 m mesh in an area of ​​60 m x 200 m, and the "X" marks represent principal component scores where the ratio is less than 60%. "PC2=-4.5×PC1-4.5" corresponds to the first boundary line (first threshold) between the area marked with "◯" and the area marked with "X".

[0048] According to Fig. 10, it is preferable to arrange the antenna units so that the four values ​​of depression angle a (tilt angle), height b, half-width c, and interval d satisfy "PC2 ≧ -4.5 × PC1 -4.5". By arranging the antenna units in this way, the ratio of the coverage area that can obtain a throughput of 2 Gbps or more can be 60% or more of the 60m × 200m area. In other words, the antenna set 10 can form a communication area between the antenna set 10 and the ground where a relatively high throughput can be obtained.

[0049] Fig. 11 is a scatter plot of principal component scores obtained by substituting the above 19 types of individual data into the first principal component PC1 and the second principal component PC2. In Fig. 11, the "◯" marks represent principal component scores where the ratio of reception points where a throughput of 2 Gbps or more is measured is 78% or more among all reception points arranged in a 1 m mesh in an area of ​​60 m x 200 m, and the "X" marks represent principal component scores where the ratio is less than 78%. "PC2 = 0.15 x PC1 + 1.0" corresponds to the second boundary line (second threshold) between the area marked with "◯" and the area marked with "X".

[0050] According to Fig. 11, it is preferable to arrange the multiple antenna units so that the four values ​​of depression angle a (tilt angle), height b, half-width c, and interval d satisfy "PC2 ≧ -4.5 × PC1 -4.5 and PC2 ≧ 0.15 × PC1 + 1.0". By arranging them in this way, the ratio of the coverage area where a throughput of 2 Gbps or more can be obtained can be 78% or more of the 60m × 200m area. In other words, the antenna set 10 can form a communication area between the ground and the antenna set 10, where a relatively high throughput can be obtained.

[0051] 12 is a diagram showing a schematic plan view of a square area formed around two adjacent antenna units. When viewed from a direction perpendicular to the horizontal plane (in plan view), the length of the line segment k1 connecting the first antenna unit 11 and the second antenna unit 12 is d, the point obtained by extending the line segment k1 from the first antenna unit 11 by 0.5×d is p1, the point obtained by extending the line segment k1 from the second antenna unit 12 by 0.5×d is p2, the straight line passing through p1 and p2 is L1, the straight line passing through point p1 and perpendicular to the straight line L1 is L2, the straight line passing through point p2 and perpendicular to the straight line L1 is L3, the straight line parallel to the straight line L1 and farthest within a range that does not intersect with an obstacle (obstruction) that blocks radio wave propagation is L4, and the square area enclosed by the straight lines L1, L2, L3, and L4 is S. In this case, it is preferable that the first antenna unit 11 and the second antenna unit 12 are arranged so that the ratio of areas that can obtain a throughput of 1 Gbps or more is 90% or more of the rectangular area S. The above-mentioned Fig. 8 shows the conditions under which the ratio of areas that can obtain a throughput of 1 Gbps or more is 90% or more of the rectangular area S.

[0052] The lengths of the straight lines L2 and L3 may be fixed within a range in which they do not intersect with obstacles (blocking objects) that impede radio wave propagation, and may be, for example, d, 1.5×d, or 2×d.

[0053] Fig. 13 is a cross-sectional view showing an example of an antenna unit installed on the outer circumferential surface of a pole. The antenna unit has a plurality of radiating elements 73. In Fig. 13, four antennas A1, A2, A3, and A4 are illustrated as the plurality of radiating elements 73. The plurality of radiating elements 73 are provided on a dielectric flexible substrate 72 having a conductor 75 on the back surface.

[0054] 13, four radiating elements 73 are arranged at 90° intervals on the outer circumferential surface of the pole, but the number of radiating elements 73 may be less than four. For example, three radiating elements 73 may be arranged at 120° intervals, or two radiating elements 73 may be arranged at 180° intervals. The number of radiating elements 73 may be more than four. For example, six radiating elements 73 may be arranged at 60° intervals, or eight radiating elements 73 may be arranged at 45° intervals.

[0055] 13, the radiating element 73 is an antenna conductor formed to be capable of transmitting and receiving radio waves in a desired frequency band. Examples of the desired frequency band include the UHF (Ultra High Frequency) band with a frequency of 0.3 to 3 GHz, the SHF (Super High Frequency) band with a frequency of 3 to 30 GHz, and the EHF (Extremely High Frequency) band with a frequency of 30 to 300 GHz. The radiating element 73 functions as a radiator.

[0056] The radiating element 73 is provided on the first principal surface on the outside of the base material 72. The radiating element 73 may be formed by printing a metal material so as to overlap at least a portion of the ceramic layer provided on the first principal surface of the base material 72. In this way, the radiating element 73 is provided on the first principal surface of the base material 72, straddling the portion where the ceramic layer is formed and the other portion.

[0057] The radiating element 73 is, for example, a conductor formed in a planar shape. The metal material forming the radiating element 73 may be a conductive material such as gold, silver, copper, aluminum, chromium, lead, zinc, nickel, or platinum. The conductive material may be an alloy, such as an alloy of copper and zinc (brass), an alloy of silver and copper, or an alloy of silver and aluminum. The radiating element 73 may be a thin film. The shape of the radiating element 73 may be, but is not limited to, a rectangular or circular shape.

[0058] Alternative materials for forming the radiating element 73 include Fluorine-Doped Tin Oxide (FTO) and Indium Tin Oxide (ITO).

[0059] The ceramic layer described above can be formed on the first main surface of the base material 72 by printing or the like. By providing the ceramic layer, the wiring (not shown) attached to the radiating element 73 can be covered and hidden, resulting in a good design. In this embodiment, the ceramic layer does not have to be provided on the first main surface, and may be provided on the second main surface inside the base material 72. Providing the ceramic layer on the first main surface of the base material 72 is preferable, because the radiating element 73 and the ceramic layer can be provided on the base material 72 by printing in the same process.

[0060] The material of the ceramic layer is glass frit or the like, and the thickness thereof is preferably 1 to 20 μm.

[0061] In this embodiment, the radiating element 73 is provided on the first main surface of the base material 72, but may be provided inside the base material 72. In this case, the radiating element 73 can be provided inside the base material 72 in the form of, for example, a coil.

[0062] The base material 72 is, for example, a substrate provided along the outer circumferential surface of the pole. The base material 72 is, for example, rectangular in plan view and has a first main surface and a second main surface. The first main surface of the base material 72 is provided so as to face outward. The second main surface of the base material 72 is provided so as to face inward.

[0063] The material forming the base material 72 is designed according to the antenna performance such as the power and directivity required for the radiating element 73, and may be, for example, a dielectric material such as glass or resin, a metal, or a composite of these.

[0064] When a resin is used as the base material 72, the resin is preferably a transparent resin, and examples of the resin include polyethylene terephthalate, polyethylene, liquid crystal polymer (LCP), polyimide (PI), polyphenylene ether (PPE), polycarbonate, acrylic resin, and fluororesin. Fluororesin is preferable because of its low dielectric constant.

[0065] Examples of fluororesins include ethylene-tetrafluoroethylene copolymers (hereinafter also referred to as "ETFE"), hexafluoropropylene-tetrafluoroethylene copolymers (hereinafter also referred to as "FEP"), tetrafluoroethylene-propylene copolymers, tetrafluoroethylene-hexafluoropropylene-propylene copolymers, perfluoro(alkyl vinyl ether)-tetrafluoroethylene copolymers (hereinafter also referred to as "PFA"), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers (hereinafter also referred to as "THV"), polyvinylidene fluoride (hereinafter also referred to as "PVDF"), vinylidene fluoride-hexafluoropropylene copolymers, polyvinyl fluoride, chlorotrifluoroethylene polymers, ethylene-chlorotrifluoroethylene copolymers (hereinafter also referred to as "ECTFE"), polytetrafluoroethylene, etc. Any one of these may be used alone, or two or more may be used in combination.

[0066] The fluororesin is preferably at least one selected from the group consisting of ETFE, FEP, PFA, PVDF, ECTFE and THV, and ETFE is particularly preferred because of its excellent transparency, processability and weather resistance.

[0067] Moreover, Aflex (registered trademark) may be used as the fluororesin.

[0068] The thickness h of the base material 72 is preferably 25 μm to 10 mm. The thickness h of the base material 72 can be designed arbitrarily depending on the location where the radiating element 73 is arranged.

[0069] When the substrate 72 is made of a resin, it is preferable to use a resin formed into a film or sheet. The thickness h of the film or sheet is preferably 25 to 1000 μm, more preferably 100 to 800 μm, and particularly preferably 100 to 500 μm, in terms of excellent antenna holding strength.

[0070] The surface resistivity of the conductor 75 is preferably 20 Ω / □ (ohms per square) or less, more preferably 10 Ω / □ or less, and further preferably 5 Ω / □ or less. The conductor 75 is preferably wider than the substrate 72, but may be narrower than the substrate 72.

[0071] The thickness of the conductor 75 is preferably 400 nm or less, and more preferably 300 nm or less. The lower limit of the thickness of the conductor 75 is not particularly limited, but may be 2 nm or more, 10 nm or more, or 30 nm or more.

[0072] The radiating element 73 is a patch element (patch antenna), but may be another element such as a dipole element (dipole antenna).

[0073] In addition, since other antenna units such as the second antenna unit 12 may have the same shape as the first antenna unit 11, the description of the shapes of the other antenna units will be omitted by incorporating the above description of the shape of the first antenna unit 11.

[0074] Next, an example of the results of calculating throughput in a simulation will be described.

[0075] [Table 1] Table 1 shows the simulation conditions when calculating the throughput in the simulation. Figures 14, 15, and 16 show the radiation patterns of the multiple antenna units used in the simulation. The radiation patterns of the multiple antenna units used in the simulation are all the same.

[0076] FIG. 14 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) with an azimuth angle of 0° and in the XY plane when a beam of 11 dBi is radiated at a tilt angle of 5° with respect to the XY plane. FIG. 15 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) with an azimuth angle of 0° and in the XY plane when a beam of 11 dBi is radiated at a tilt angle of 10° with respect to the XY plane. FIG. 16 is a diagram showing an example of the directivity of an antenna unit in a vertical plane (XZ plane) with an azimuth angle of 0° and in the XY plane when a beam of 14 dBi is radiated at a tilt angle of 10° with respect to the XY plane. In this example, a gain of 11 dBi corresponds to a half-width of 10°, and a gain of 14 dBi corresponds to a half-width of 5°.

[0077] Fig. 17 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics of Fig. 14 are arranged at 20 m intervals. Fig. 18 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics of Fig. 15 are arranged at 20 m intervals. Fig. 19 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics of Fig. 16 are arranged at 20 m intervals. Fig. 20 is a distribution diagram showing an example of the throughput obtained when three antenna units having the characteristics of Fig. 14 are arranged in the same place.

[0078] 17 to 20, the distributed arrangement type (FIGS. 17 to 19) results in a communication area that can provide a higher throughput than the centralized arrangement type (FIG. 20).

[0079] Although the antenna set has been described above by way of an embodiment, the present invention is not limited to the above embodiment. Various modifications and improvements, such as combinations or substitutions with part or all of other embodiments, are possible within the scope of the present invention.

[0080] The structure on which the antenna unit is installed is not limited to a pole. The antenna unit may be installed on a structure fixed to the ground, such as a utility pole, a utility pole, a street light, a traffic light, a sign, or a building.

[0081] The antenna set may also have two or four or more antenna units that transmit streams in distributed MIMO. By having four or more antenna units, a communication area with higher throughput can be formed. Also, the number of people that can be accommodated in the communication area can be increased.

[0082] This international application claims priority to Japanese Patent Application No. 2020-186500, filed on November 9, 2020, and the entire contents of Japanese Patent Application No. 2020-186500 are incorporated herein by reference. [Explanation of symbols]

[0083] 1,2,3 Pole 10 Antenna Set 11,12,13 Antenna unit 41, 42, 43, 44, 45, 46, 47, 48 Building 50,52 road 51 Intersection 72 Base material 75 Conductor

Claims

1. An antenna set including antenna units for transmitting streams in distributed MIMO, The antenna unit group includes a plurality of antenna units arranged apart from each other, The antenna set includes a plurality of antenna units installed at a height of 3 m or more and 8 m or less, a radiation pattern having an omnidirectional angle of 180 degrees or more in a horizontal plane, and a main lobe radiation peak inclined at a depression angle of more than 0 degrees and not more than 15 degrees.

2. The antenna set according to claim 1 , wherein the main lobe of each of the plurality of antenna units has a half-width of 6 degrees or more and 15 degrees or less.

3. 3. The antenna set according to claim 1, wherein each of the plurality of antenna units has a radiation pattern that is omnidirectional in a horizontal plane.

4. The plurality of antenna units includes two antenna units adjacent to each other, The antenna set according to claim 1 , wherein the distance between the two antenna units is between 10 m and 80 m.

5. Let a be the average depression angle of each of the plurality of antenna units, a be the average installation height of each of the plurality of antenna units, b be the average half-width of the main lobe radiated from each of the plurality of antenna units, c be the average half-width of the main lobe radiated from each of the plurality of antenna units, and d be the average spacing between adjacent antenna units included in the plurality of antenna units. PC1=-(a / 10.6)-(b / 10.8)+(c / 5.7)+(d / 19.8)-1.8 PC2=(a / 12.0)+(b / 2.5)+(c / 6.6)+(d / 99.6)-4.9 PC2 ≧−4.5×PC1−4.5 The antenna set according to claim 1 , wherein

6. An antenna set as described in any one of claims 1 to 5, wherein at a point where the level of the direct wave of the radio wave transmitted from an antenna unit included in the antenna unit group is maximum, "the level [dB] of the reflected wave of the radio wave ÷ the level [dB] of the direct wave of the radio wave" is 0.7 or more and 0.95 or less.

7. The antenna set according to claim 1 , further comprising a reflector that reflects radio waves between adjacent antenna units included in the plurality of antenna units.

8. the antenna unit group includes a first antenna unit and a second antenna unit adjacent to the first antenna unit, When viewed from a direction perpendicular to a horizontal plane, the length of the line segment connecting the first antenna unit and the second antenna unit is d, p1 is a point obtained by extending the line segment by 0.5×d from the first antenna unit, p2 is a point obtained by extending the line segment by 0.5×d from the second antenna unit, L1 is a line passing through p1 and p2, L2 is a line passing through point p1 and perpendicular to line L1, L3 is a line passing through point p2 and perpendicular to line L1, L4 is the farthest line that is parallel to line L1 and does not intersect with any obstacles that obstruct radio wave propagation, and S is a rectangular area enclosed by lines L1, L2, L3, and L4. The antenna set according to claim 1 , wherein the first antenna unit and the second antenna unit are arranged so that a proportion of an area in a rectangular area S where a throughput of 1 Gbps or more can be obtained is 90% or more.

9. 9. An antenna set according to any one of claims 1 to 8, wherein the antenna units are mounted on a land-based structure.

10. The antenna set according to claim 9 , wherein the structure is a utility pole, a utility pole, a street light, a traffic light, a sign or a building.

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