JP5208077B2 - Sector antenna device - Google Patents

Description

The present invention relates to a sector antenna apparatus having sufficient mechanical strength and sufficient back lobe characteristics.

  As an example of a conventional technique for realizing a small directional antenna, there is a phase difference feeding two-element dipole array antenna shown in Non-Patent Document 1. In this example, as shown in FIGS. 11 and 12, the two-element array antenna is fed with a phase difference of 90 degrees. In the figure, 21 is a dipole antenna, 22 is a feeding point, 23 is a monopole antenna, Reference numeral 24 denotes a ground plane, 25 denotes a hybrid phase shifter, and 26 denotes a feed line.

The dipole antenna 21 or the monopole antenna 23 is arranged at 0.25 wavelength intervals (see FIG. 11), and it is proposed to supply power by giving a power supply phase difference of 90 degrees. Here, as apparent from the fact that the voltage at the feeding point 22 is described as “+1 [V]” and “−j [V]” (j is an imaginary unit), in the conventional technique, the excitation condition is the excitation condition. It is clear that the amplitude ratio is 1 (1: 1) and the excitation phase difference is 90 degrees (the absolute value of Arctan ((−j) / (+ 1))).
Further, in the experiment of Non-Patent Document 1, as shown in FIG. 12, a feed line is formed using a hybrid circuit 25 in which a monopole antenna 23 is disposed on a ground plane 24 and an excitation condition phase difference of 90 degrees can be distributed with equal power. 26 is used to supply power. Here again, as is clear from the output from the hybrid phase shifter 25 to the two antennas being “−90 °” and “−180 °”, in the prior art, the excitation condition is the excitation phase difference. It is clear that the angle is 90 degrees (difference between -90 ° and -180 °).
Further, in Non-Patent Document 1, since the frequency is defined as f = 2.45 GHz, the wavelength λ in free space is λ = c / f = 12.4 mm. It can be seen that it is 0.25 times the free space wavelength (c is the speed of light in free space, 299, 792, 458 m / s).

Kotaro Era, “Phase difference feeding two-element dipole array antenna”, IEICE Society Conference, 2005, B-1 P130

By the way, in Non-Patent Document 1, it cannot be said that the back lobe characteristic is sufficient. Furthermore, since the diameter of the element antenna is 2 mm, it cannot be said that the element antenna has a mechanical strength that is assumed to be installed outdoors. Furthermore, when using a thick pipe-like metal to give the mechanical strength of the element antenna, the back lobe characteristics may be deteriorated because no deviation from the design due to mutual coupling between the element antennas is assumed. is there.
Since there is mutual coupling between the element antennas, the configuration according to Non-Patent Document 1 can be developed into a collinear array configuration to increase the gain, or a plurality of antennas can be arranged close to each other for direction estimation. Therefore, it is difficult to suppress the characteristic deterioration that occurs.

  Monopole antennas, dipole antennas, and slot antennas are low-cost, lightweight, and have a small wind receiving area. In the case of creating a directional antenna device using these antennas, there is a method of supplying power with a phase difference using these antennas as element antennas. However, the element antenna has a trade-off relationship that the larger the diameter, the higher the mechanical strength, and the larger the diameter, the larger the mutual coupling and the worse the back lobe characteristics in the conventional method.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a sector antenna apparatus that satisfies sufficient back lobe characteristics while taking into account mechanical strength and mutual coupling between element antennas.

To achieve the above object, a sector antenna apparatus according to the present invention uses any one of two monopole antennas, dipole antennas, or slot antennas as element antennas, and the element antennas are on the same plane. A sector antenna device in which a plurality of the sector antennas are arranged to form a sector antenna, wherein the two antenna elements are spaced apart from each other in a direction perpendicular to the axial direction. Arranged parallel to each other with respect to the axial direction, the excitation condition is an excitation amplitude ratio of a positive number less than 1, and the plurality of sector antennas are arranged at intervals from each other in a direction perpendicular to the plane. The element antennas are offset from each other in the axial direction .

In addition, the sector antenna apparatus according to the present invention uses any one of two monopole antennas, dipole antennas, or slot antennas as element antennas, and the element antennas are arranged on the same plane to be sector antennas. A plurality of the sector antennas, wherein the sector antennas are arranged on the same straight line to form a collinear antenna, and the two collinear antennas are arranged. Are arranged in parallel to each other in a direction orthogonal to the axial direction so that the positions in the axial direction are aligned in parallel, and the excitation condition is a positive number with an excitation amplitude ratio of less than 1, and the plurality of sector antennas Are arranged at intervals in a direction perpendicular to the plane, and the positions of the element antennas in the axial direction are not mutually aligned. And wherein the are.

In the sector antenna apparatus according to the present invention, the parallel spacing of the element antennas in the sector antenna is set to be 0.125 times or more and 0.25 times or less of a free space wavelength at an applied frequency, and excitation of the two element antennas is performed. The condition may be that the excitation amplitude ratio is 1/10 or more and 1.9 or less and the excitation phase difference is 20 degrees or more and 100 degrees or less.

In the sector antenna apparatus according to the present invention, the parallel spacing of the element antennas in the sector antenna is 0.125 times the free space wavelength at the applied frequency, and the excitation condition of the two element antennas is an excitation amplitude ratio May be 1/6 or more and 2.7 or less, and the excitation phase difference may be 35 degrees or more and 80 degrees or less.

In the sector antenna device according to the present invention, the parallel interval of the element antennas in the sector antenna is 0.25 times the free space wavelength at the applied frequency, and the excitation condition of the two element antennas is an excitation amplitude ratio May be from 4.3 to 2.1, and the excitation phase difference may be from 32 degrees to 70 degrees.

  In the sector antenna device according to the present invention, the arrayed sector antennas have an interval in a direction orthogonal to the plane of 0.5 times a free space wavelength, and a displacement of an axial position of the element antenna. Is 0.2 times to 1.0 times the free space wavelength, or 0.38 times to 0.7 times.

  The sector antenna apparatus according to the present invention is characterized in that there are two sector antennas, and the excitation amplitude of one sector antenna is zero.

In the present invention, it is possible to provide a technology for realizing a sector antenna device that satisfies sufficient back lobe characteristics while considering mutual coupling between element antennas. Accordingly, in a directional antenna device using a monopole antenna, a dipole antenna, and a slot antenna having sufficient mechanical strength (diameter) as element antennas, a sector antenna device having planar directivity satisfying sufficient back lobe characteristics Can be provided. As a result, it is possible to provide a directional antenna that is low-cost, lightweight, has a small wind receiving area, and has sufficient mechanical strength and sufficient back lobe characteristics.

It is a figure which shows an example of the 1st Example of this invention. It is a figure which shows an example of the 2nd Example of this invention. It is a figure which shows an example of the 3rd, 4th, 5th Example of this invention. It is a figure explaining the 3rd, 4th, 5th Example of this invention, and is a figure showing the excitation amplitude ratio dependence of the beam width of a main lobe and a back lobe characteristic. It is a figure explaining the 3rd, 4th, 5th Example of this invention, and is a figure showing the excitation phase difference dependence of the beam width of a main lobe and a back lobe characteristic. It is a simulation result of the horizontal plane directivity characteristic by the 4th example of the present invention. It is a simulation result of the horizontal plane directivity characteristic by the 5th example of the present invention. It is a figure which shows the 6th Example of this invention. It is a figure for demonstrating the 6th Example of this invention. It is a figure for demonstrating the 6th Example of this invention. It is a figure for demonstrating the conventional phase difference electric power feeding antenna structure. It is a figure for demonstrating the conventional phase difference electric power feeding antenna structure.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIG.
In FIG. 1, reference numeral 1 denotes a dipole antenna. In the antenna device 11a of the first embodiment, the dipole antenna 1 is configured as an element antenna.
In the antenna device 11a, the two dipole antennas 1 are arranged in parallel with a predetermined interval d1 in the direction orthogonal to the direction of the axis 10 with the same direction of the axis 10. The two dipole antennas 1 have the same position with respect to the direction of the axis 10.
The excitation condition of the dipole antenna 1 is a positive number less than 1.
In the present embodiment, the dipole antenna 1 is used as the element antenna. However, a monopole antenna or a slot antenna can be used instead of the dipole antenna 1. This is not limited to the present embodiment, but can be applied to all the following embodiments. Hereinafter, the dipole antenna 1 will be described as an example.

(Second embodiment)
Next, a second embodiment will be described with reference to FIG.
In FIG. 2, reference numeral 7 denotes a collinear antenna in which two dipole antennas 1 are arranged on the same straight line and their axes 10 are aligned and connected to form an array.
In the antenna device 11b of the second embodiment, two collinear antennas 7 are installed in parallel at a predetermined interval d1 in a direction perpendicular to the direction of the axis 10. The two collinear antennas 7 have the same position in the direction of the axis 10. A plurality of dipole antennas 1 constituting the antenna device 11 b are arranged on the same plane 9.
Here, by supplying power by giving excitation amplitude and phase difference between two dipole antennas 1 adjacent to each other in the direction orthogonal to the direction of the axis 10, the directivity of horizontal plane (plane orthogonal to the plane 9) is realized. The gain can be increased by applying the same excitation amplitude and the same excitation phase between two dipole antennas 1 adjacent to each other in the direction of the axis 10.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. As shown in FIG. 3, the antenna device 11c according to the third embodiment has the same configuration as the antenna device 11b of the second embodiment shown in FIG. 2, and is a dipole that is separated in a direction orthogonal to the direction of the axis 10 The distance between the antennas 1 (between the central axes 10) d1 has a length of either 0.125 wavelength or 0.25 wavelength.
The diameter R of the dipole antenna 1 is 0.067 wavelength.

The excitation amplitude and phase difference are shown in FIGS. 4 and 5, respectively. These figures are obtained by the analysis of the moment method.
FIG. 4 is a diagram showing the dependency of the main lobe beam width and the back lobe characteristics on the excitation amplitude ratio. The simulation is performed when the distance d1 between adjacent dipole antennas 1 is 0.125 wavelength and 0.25 wavelength. It is a result.
FIG. 5 shows the excitation phase difference dependence of the main lobe beam width and the back lobe characteristics. The distance d1 between adjacent dipole antennas 1 is 0.125 wavelength and 0.25 wavelength. There are simulation results. Here, the signal wavelength is assumed to be a short wave or a VUHF band.

  In FIG. 4, when the distance d1 between the adjacent dipole antennas 1 is 0.125 times the free space wavelength, and the excitation amplitude ratio is 1/10 or more and 2.7 or less, the back is −15 dB or less. It can be seen that the lobe characteristics can be secured. Alternatively, when the distance d1 between adjacent dipole antennas 1 is 0.25 times the free space wavelength, if the excitation amplitude ratio is 1/6 or more and 1 / 1.9 or less, a back lobe characteristic of 15 dB or more is obtained. It can be seen that it can be secured.

  In FIG. 5, when the distance d1 between adjacent dipole antennas 1 is 0.125 times the free space wavelength, a back lobe characteristic of −15 dB or less is ensured if the excitation phase difference is 20 degrees or more and 100 degrees or less. I understand that I can do it. Alternatively, when the distance d1 between adjacent dipole antennas 1 is 0.25 times the free space wavelength, a back lobe characteristic of −15 dB or less can be ensured if the excitation phase difference is 20 degrees or more and 83 degrees or less. I understand that.

The characteristics when the distance d1 between the adjacent dipole antennas 1 is not less than 0.125 wavelengths and not more than 0.25 wavelengths can be interpolated from FIGS.
Here, when the distance d1 between the adjacent dipole antennas 1 is set to 0.125 wavelength to 0.25 wavelength, the excitation condition is set to 1/10 or more and 1.9 or less as an excitation condition. When the phase difference is 20 degrees or more and 100 degrees or less, the worst value of the back lobe characteristic can be suppressed to -15 dB or less. Thereby, it can be used even in a base station of a radio system that requires interference suppression from the rear.

Therefore, in order to ensure a backlobe characteristic of −15 dB or less, the parallel interval d1 of the dipole antenna 1 is set to an interval of 0.125 to 0.25 times the free space wavelength at the frequency to be applied, and 2 It can be seen that the excitation conditions of the two dipole antennas 1 may be an excitation amplitude ratio of 1/10 to 1.9 and an excitation phase difference of 20 degrees to 100 degrees.
In the present embodiment, since the distance d1 between adjacent dipole antennas 1 is 0.125 wavelength or more and 0.25 wavelengths or less, the diameter R of the dipole antenna 1 is 0.067 wavelength, so R / d1 is 1 / It is in a situation where the influence of mutual coupling between the element antennas can occur. However, in the configuration of this embodiment, each figure shows that sufficient back lobe characteristics are ensured while considering mutual coupling between element antennas.
For example, when a frequency of 285 MHz is used, 0.067 wavelength corresponds to 70 mm. Therefore, at 285 MHz, an antenna having a diameter R = 70 mm of the dipole antenna 1 is arranged with a distance d1 between the dipole antennas 1 being 130 mm or more and 260 mm or less. It corresponds to doing. If the diameter R of the dipole antenna 1 is 70 mm, the mechanical strength is sufficient.

(Fourth embodiment)
Furthermore, in order to improve the back lobe characteristics, the method of the fourth embodiment described below may be used. In the fourth embodiment, the antenna device 11c of the third embodiment shown in FIG. 3 is used, and the excitation amplitude / phase difference is the same as the excitation amplitude / phase difference of the third embodiment shown in FIGS. The same.

In FIG. 4, when the distance d1 between adjacent dipole antennas 1 is 0.125 times the free space wavelength, if the excitation amplitude ratio is 1/6 or more and 2.7 or less, the back is −20 dB or less. It can be seen that the lobe characteristics can be secured. In FIG. 5, when the distance d1 between adjacent dipole antennas 1 is 0.125 times the free space wavelength, if the excitation phase difference is 35 degrees or more and 80 degrees or less, a back lobe characteristic of −20 dB or less is secured. I understand that I can do it.
Therefore, in order to ensure a backlobe characteristic of −20 dB or less, the parallel interval d1 between adjacent dipole antennas 1 is set to an interval of 0.125 of the free space wavelength at the frequency to be applied, and the two dipole antennas 1 It can be seen that as the excitation conditions, the excitation amplitude ratio is set to 1/6 or more and 2.7 or less and the excitation phase difference is set to 35 degrees or more and 80 degrees or less.

Here, the simulation result of the horizontal plane directivity in the present embodiment is shown in FIG.
In the collinear antenna 7, the same dipole antenna 1 is arranged on the same straight line at intervals of 0.5 wavelength. FIG. 6 shows the horizontal plane directivity when the excitation amplitude is ¼ and the excitation phase difference is 60 degrees. FIG. 6 also shows that the back lobe characteristic is −30 dB.

(Fifth embodiment)
When the back lobe characteristics are improved by a method different from that of the fourth embodiment, the method of the fifth embodiment described below may be used. In the fifth embodiment, the antenna device 11c of the third embodiment shown in FIG. 3 is used, and the excitation amplitude / phase difference is the same as the excitation amplitude / phase difference of the third embodiment shown in FIGS. The same.
In FIG. 4, when the distance d1 between adjacent dipole antennas 1 is 0.25 times the free space wavelength, if the excitation amplitude ratio is not less than 4.3 and not more than 2.1, it is not less than 20 dB. It can be seen that the back lobe characteristics can be secured. In FIG. 5, when the distance d1 between adjacent dipole antennas 1 is 0.25 times the free space wavelength, if the excitation phase difference is 32 degrees or more and 70 degrees or less, a back lobe characteristic of −20 dB or less is secured. I understand that I can do it.
Therefore, in order to ensure a backlobe characteristic of −20 dB or less, the parallel interval d1 of the dipole antenna 1 is set to an interval of 0.25 of the free space wavelength at the frequency to be applied, and the excitation condition of the two element antennas It can be seen that the excitation amplitude ratio should be not less than 4.3 and not more than 1/2, and the excitation phase difference should be not less than 32 degrees and not more than 70 degrees.

Here, the simulation result of the horizontal plane directivity in this embodiment is shown in FIG.
In the collinear antenna 7, the same antennas are arranged on the same straight line at intervals of 0.5 wavelengths. FIG. 7 shows the horizontal plane directivity when the excitation amplitude is ¼ and the excitation phase difference is 60 degrees. It can be seen from the figure that the back lobe characteristic is -20 dB or less.

(Sixth embodiment)
Next, a sixth embodiment will be described with reference to FIGS.
As shown in FIG. 8, 1 is a dipole antenna, 7 is a collinear antenna in which two identical dipole antennas 1 are arranged on the same straight line, and 8 is a sector antenna.
In the sixth embodiment, two collinear antennas 7 are installed in parallel with a predetermined distance d1 in a direction (y-axis direction in the figure) perpendicular to the direction of the axis 10, and the four dipole antennas 1 are A sector antenna 8 is configured on the same plane 9. The two collinear antennas 7 have the same position in the direction of the axis 10 (the z-axis direction in the figure).
The two sector antennas 8 are arranged in parallel at a distance of 0.5 wavelengths in the direction orthogonal to the plane 9 to constitute a sector antenna device 11d according to the sixth embodiment.
The two sector antennas 8 are arranged shifted by 0.5 wavelength (d3 in the figure) in the z-axis direction.

  As described above, a plurality of dipole antennas 1 are aligned in the x-axis direction and the z-axis direction and arranged on the same plane, thereby realizing a directional antenna and reducing the directivity in the z-axis direction. A collinear antenna 7 configuration that achieves high gain can be obtained. Further, it is assumed that these collinear antennas 7 are sector antennas 8 and are used for direction estimation by being arranged at intervals of d2 for 0.5 wavelengths in the y-axis direction.

  Normally, if the same antenna is arranged as it is in the y-axis direction for direction estimation, the directivity is deteriorated due to mutual coupling. Therefore, a method is used in which mutual coupling is suppressed not only by arranging in the y-axis direction but also by shifting the sector antennas 8 in the z-axis direction.

FIG. 9 shows the result of analysis using the method of moments to determine how much the characteristic deterioration can be suppressed when the sector antenna 8 is shifted in the z-axis direction at 0.5 wavelength intervals. From the figure, when the shift in the z-axis direction between one sector antenna 8 is set to 0.2 wavelength to 1.0 wavelength, the back lobe characteristic can be improved to −15 dB or less, and further, from 0.38 wavelength to 0. When the arrangement is shifted by 7 wavelengths, the back lobe characteristics can be improved to -20 dB or less.
As an example, the horizontal plane directivity when shifted by 0.5 wavelength is shown in FIG. It can be seen from the figure that the degradation of the main lobe is small and the back lobe characteristic is suppressed to −20 dB or less (180 ° direction).

Next, effects of the antenna device and the sector antenna device described above will be described with reference to the drawings.
The monopole antenna, the dipole antenna 1, and the slot antenna are low-cost, lightweight, and have a small wind receiving area. In the case of creating a directional antenna device using these antennas, there is a method of supplying power with a phase difference using these antennas as element antennas. However, the element antenna has a trade-off relationship that the mechanical strength can be obtained as the diameter of the element antenna increases, and that the larger the diameter of the element antenna, the larger the mutual coupling and the worse the back lobe characteristics in the conventional method. there were.
The present invention provides a technology for realizing an antenna device that satisfies sufficient back lobe characteristics while taking into account mutual coupling between element antennas. Therefore, in a directional antenna device using a monopole antenna, a dipole antenna, and a slot antenna having sufficient mechanical strength (diameter) as element antennas, an antenna device having planar directivity satisfying sufficient back lobe characteristics is provided. It becomes possible to provide. As a result, it is possible to provide a directional antenna that is low-cost, lightweight, has a small wind receiving area, and has sufficient mechanical strength and sufficient back lobe characteristics.

Although the embodiments of the antenna device and the sector antenna device according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the scope of the present invention.
For example, in the above-described second to sixth embodiments, the collinear antenna 7 has two dipole antennas 1 arranged in the direction of the axis 10, but as the collinear antenna 7 in which two or more dipole antennas 1 are arranged. Also good.
In the sixth embodiment, the sector antenna device 11d is composed of the two sector antennas 8. However, two or more sector antennas 8 may be provided in the sector antenna device 11d.

1 Dipole Antenna 7 Collinear Antenna 8 Sector Antenna 9 Plane 10 Axis 11a, 11b, 11c Antenna Device 11d Sector Antenna Device d1, d2 Spacing

Claims (7)

Any one of two monopole antennas, dipole antennas, or slot antennas is used as an element antenna. The element antennas are arranged on the same plane to form a sector antenna, and a plurality of the sector antennas are arranged. A sector antenna device,
The sector antenna is
The two element antennas are arranged in parallel with a position in the axial direction spaced apart from each other in a direction perpendicular to the axial direction, and the excitation condition is a positive number whose excitation amplitude ratio is less than 1 .
The plurality of the sector antennas are arranged spaced from one another in a direction perpendicular to the plane, the sector antenna apparatus characterized by position relative to the axial direction of the antenna elements are shifted from each other Any one of two monopole antennas, dipole antennas, or slot antennas is used as an element antenna. The element antennas are arranged on the same plane to form a sector antenna, and a plurality of the sector antennas are arranged. A sector antenna device,
The sector antenna is
A plurality of the element antennas are arranged on the same straight line to constitute a collinear antenna,
The two collinear antennas are arranged parallel to each other in the direction orthogonal to the axial direction and in parallel with the position in the axial direction, and the excitation condition is a positive number whose excitation amplitude ratio is less than 1 .
A plurality of said sector antenna are arranged spaced from one another in a direction perpendicular to the plane, the sector antenna apparatus positioned with respect to the axial direction, characterized in that are offset from each other of said element antennas. The sector antenna apparatus according to claim 1 or 2,
The parallel spacing of the element antennas in the sector antenna is 0.125 times or more and 0.25 times or less of the free space wavelength at the applied frequency, and the excitation condition of the two element antennas is an excitation amplitude ratio of 1/10. The sector antenna apparatus characterized in that it is 1.9 or less and the excitation phase difference is 20 degrees or more and 100 degrees or less. The sector antenna apparatus according to claim 1 or 2,
The parallel spacing of the element antennas in the sector antenna is 0.125 times the free space wavelength at the applied frequency, and the excitation condition of the two element antennas is that the excitation amplitude ratio is 1/6 or more and 2.7 minutes and 1 or less, the sector antenna apparatus excitation phase difference, characterized in that the 80 degrees or less than 35 degrees. The sector antenna apparatus according to claim 1 or 2,
The parallel spacing of the element antennas in the sector antenna is 0.25 times the free space wavelength at the applied frequency, and the excitation condition of the two element antennas is an excitation amplitude ratio of 4.3 / 3 or more 2.1. and min 1 below, the sector antenna apparatus characterized by excitation phase difference is less 70 degrees 32 degrees. In the sector antenna device according to any one of claims 1 to 5 ,
In the arrayed sector antennas, the interval in the direction orthogonal to the plane is 0.5 times the free space wavelength, and the positional deviation of the element antenna with respect to the axial direction is 0.2 times or more the free space wavelength 1 A sector antenna device characterized in that it is 0 times or less, or 0.38 times or more and 0.7 times or less. In the sector antenna device according to any one of claims 1 to 6 ,
It said sector antenna 2 Tsutoshi, and the sector antenna apparatus characterized by excitation amplitude of one of said sector antenna is 0.

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