JPH11330848A - Base station antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antenna device in which the central axis of a beam is obtained in a direction inclined at 30 deg. from the main radiation derection of a reflector and a single dipole antenna, and directivity of almost 60 deg. is obtained in an in-horizontal face beam width. SOLUTION: Unidirectional side face reflectors 21 and 22 are provided at the both side edges of a rectangular plane reflector 1, and dipole antennas 31 and 32 in parallel to the reflectors 1, 21, and 22 are provided so as to be separated from the reflector 1 by distances D1 and D2. A power is supplied via a phase shifter 4 to the antenna 32, and each width T1 and T2 of the reflectors 21 and 22 is respectively set to 0.2-0.25 λ and 0.453 λ, and the antenna 31 and 32 are positioned at a distance of 0-0.003 λ on the reflector 1 side from a straight line 5 connecting the idle edges of the reflectors 21 and 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a base station antenna device in mobile communication, and combines directional radiation beams of two dipole antennas with different phases and radiates in a direction of approximately 30 ° from a main radiation direction alone. An antenna device having a central axis of a beam and having a directivity of approximately 60 ° in a horizontal plane. In addition, the present invention relates to an antenna device in which a six-degree sector of 60 ° is configured using the antenna device, and a configuration space of the antenna and a three-sector zone of 120 ° using another frequency is shared.

[0002]

2. Description of the Related Art FIG. 16 shows a conventional antenna device of this kind. Side reflectors 21 and 22 are integrally provided on both sides (vertical side edges) of the rectangular flat reflector 1 on the same side and perpendicular to the reflector 1. Each width T1, T2 of the side reflectors 21, 22
Are both about a quarter wavelength. Further, the half-wavelength dipole antennas 31 and 32 extend in the vertical direction on the same side as the side reflectors 21 and 22 with respect to the reflector 1 and in parallel with the reflector 1 and the side reflectors 21 and 22. Placed at intervals. Reflector 1 and dipole antennas 31, 32
The distances D1 and D2 are approximately one quarter wavelength, and the horizontal distance S between the dipole antennas 31 and 32 is approximately one half wavelength. The width W of the reflector 1 is about 0.93 wavelength.

In order to make the half-width of the directivity in the horizontal plane of this antenna apparatus 60 °, that is, a so-called 60 ° beam antenna, the radiations of two dipole antennas 31 and 32 having a 120 ° beam width have the same phase and the same amplitude. It is known that they can be obtained by combining The center axes of the radiation beams are aligned with the dipole antennas 31 and 32 fed in-phase.
In order to shift 30 ° from the main radiation direction of
In the dipole antennas 31 and 32 having a 20 ° beam, the phase shifter 4 can combine the dipole antennas with a feed phase difference. FIG. 17 shows a graph in which the horizontal axis represents the phase difference and the vertical axis represents the angle of the beam center axis. Center axis is 3
To reach 0 °, it is desirable that the phase difference is large. However, considering the horizontal beam width and the side lobe level, as shown in FIG. 18, it can be seen that the beam width becomes narrower and the side lobe level becomes higher as the phase difference becomes larger.

[0004]

The radio zone configuration in the cellular mobile communication system uses a sector zone configuration in which a horizontal plane is angularly divided in order to increase the subscriber capacity and effectively use the frequency. When a six sector zone configuration is adopted, six 60 ° beam antenna devices are required to cover 360 °.

[0005] The side lobe level in the directional characteristics of the base station antenna is an important amount that determines the amount of interference between radio zones. Reducing the side lobe level allows for repeated use of frequency between closer zones. Reducing the sidelobe level is an important consideration in antenna design. Since the antenna device is installed on a steel tower or a building roof, it is not desirable to add an antenna base station. When providing mobile communication using a new frequency band, it is important to share the structural space of the antenna device in the existing antenna base station in the design of a new antenna base station in order to make effective use of the geographical area. It is an issue.

An antenna having a 120 °, 3-sector zone configuration using another frequency band which is currently employed, a 60 °,
In order to share the configuration space with the same base station using the antenna having the 6-sector zone configuration, the antenna having the 6-sector zone configuration requires the central axis of the 60 ° beam to be 120 ° in consideration of the zone configuration to be discussed later. 30 ° from beam center axis
It is desirable to be inclined.

As described above, an antenna device in which the central axis is 30 ° from the main radiation direction of two dipole antennas fed in phase and the beam width in the horizontal plane is 60 ° while maintaining a low sidelobe level is necessary.

[0008]

In a device composed of two dipole antennas and one reflector, two side reflectors protruding toward the dipole antenna are provided on both longitudinal side edges of the reflector. In two dipole antennas, a phase shifter is provided on the feed line, and in an antenna device that combines the radiation of the two dipole antennas with different phases, a side reflector close to the dipole antenna without the phase shifter on the feed line is provided. The width T2 of the other side reflector is greater than the width T1.
And the distance D2 between the reflector and the other dipole antenna is longer than the distance D1 between the reflector and the dipole antenna having no phase shifter on the feeder line. The two dipole antennas are positioned on the straight line or closer to the reflector than the straight line.

A total of two antenna devices, one of the above-described antenna devices and one of the antenna devices whose configuration conditions are reversed left and right, are vertically arranged close to each other, and a 120 ° beam antenna device using another frequency band. It is provided integrally with one antenna configuration space. Such an antenna device can cover a 120 ° zone. By arranging three antenna devices, a 360 ° zone can be covered. However, if the space diversity system is adopted to improve the communication quality, 360 antennas are provided with the six integrally provided antenna devices.
Can cover °.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 (An antenna device having a central axis of 30 ° and a beam width of 60 °) FIG. 1 shows an embodiment of the present invention, and portions corresponding to FIG. 16 are denoted by the same reference numerals. . Two dipole antennas 3
1, 32, a reflector 1, side reflectors 21 and 22 provided on both sides of the reflector 1 on the dipole antenna side, and a phase shifter 4 provided on a feed line of one dipole antenna 32.
And two dipole antennas 31, 3
Assume an antenna device that combines two radiations with different phases. In the present invention, a dipole antenna 31 having no phase shifter in the feed line, a side reflector 21 closer to the dipole antenna 31, and a side reflector closer to the dipole antenna 32 having the phase shifter 4 in the feed line due to the width T1. 22 width T
2, the distance D2 between the reflector 1 and the dipole antenna 32 is longer than the distance D1 between the reflector 1 and the dipole antenna 31, and the free edge 21a of the side reflector 21 and the free edge 22a of the side reflector 22 are separated. The dipole antennas 31 and 32 are located on the straight line or on the side of the reflector 1 with respect to the line 5 connected by the straight line.

The horizontal interval S between the dipole antennas 31 and 32 is about a half wavelength, and the width W of the reflector 1 is about 0.93 wavelength to share with a 120 ° beam antenna using another frequency band described later. It is. The widths T1, T2 of the side reflectors 21, 22 and the reflector 1 and each dipole antenna 31,
The distances D1 and D2 to the D. 32 and the feeding phase difference between the two dipole antennas 31 and 32 by the phase shifter 4 can be optimized by determining each parameter using the calculated value by the moment method.

The moment method divides an antenna into minute sections, finds the current flowing in the minute sections from boundary conditions, and knows the current distribution of the antenna, so that the electromagnetic field created by the antenna, the input / output impedance of the antenna, etc. It is a way to guide. In this embodiment, as an optimum value, the width T1 of the side reflector 21 is 0.2 to 0.25λ, the width T2 of the side reflector 22 is about 0.453λ, and each of the reflector 1 and the dipole antennas 31 and 32 is used. The distances D1 and D2 are 0 to 0 on the reflector 1 side from a straight line connecting the free edges of the side reflectors 21 and 22.
0.03λ.

The following explains that the above numerical values are optimal. The measurement was performed in a frequency band of 1.920 GHz to 2.160 GHz. FIG. 2 shows the width T1 = 0.
The figure which plotted the angle (henceforth a beam center axis angle) which the in-phase feed dipole antennas 31 and 32 make with the main radiation direction with respect to the width | variety T2 of the side reflection plate 22, when it is fixed at 25 (37.5mm). It is. The highest and lowest values in the measured frequency band were connected by a line and plotted. The distances D1 and D2 between the reflector 1 and the dipole antennas 31 and 32 are the distance at which the dipole antennas 31 and 32 are arranged on the straight line 5 connecting the free edges 21a and 21b in FIG. 1B, and the phase shift amount of the phase shifter 4. Was 60 °. From the figure, it is understood that the larger T2 is better in order to obtain a beam central axis angle of 30 °. FIG. 3 also shows the width T1 =
The width T of the side reflector 22 when it is constant at 0.25λ.
FIG. 6 is a diagram in which the beam width in the horizontal plane is plotted with respect to 2;
From this figure, it is understood that the width T2 of the side reflection plate 22 is preferably large in order to obtain a beam width in the horizontal plane of 60 °.

As described above, the larger the width T2 of the side reflector 22 is, the better the characteristics are.
The beam center axis angle with respect to the width T1 of the side reflection plate 21 and the beam width in the horizontal plane were measured at a constant value of 0.453λ (68 mm). The distances D1 and D2 between the reflector 1 and each of the dipole antennas 31 and 32 are the distance at which the dipole antennas 31 and 32 are arranged on the straight line 5 in FIG. 1B, and the phase shift amount in the phase shifter 4 is 60 °. FIG. 4 is a plot of the beam center axis angle with respect to the width T1 of the side reflector 21. From this figure, the beam center axis angle is almost 3
It is appropriate that T1 is 0.2 ° to 0.25λ to be 0 °. FIG. 5 is a plot of the beam width in the horizontal plane with respect to the width T1 of the side reflector 21. The beam width approaches 60 ° as T1 increases, and T1 = 0.2λ
From the above, it can be seen that the difference between the highest value and the lowest value is small and the frequency characteristics are good. From the above, T1 is 0.2λ or more.
0.25λ may be considered optimal.

Next, the reflector 1 and each dipole antenna 3
The beam center axis angle and the beam width with respect to the distances D1 and D2 of the phase shifters 4 and 1 and 32 will be examined. FIG.
Is the width T1 of the side reflector 21 = 0.223λ (33.5 m
m), the width T2 of the side reflector 22 = 0.453λ (68 m
m), the reflector 1 and the dipole antenna 31,
The beam center axis angle was measured when the distances D1 and D2 of 32 were changed. The horizontal axis indicates the distance between the straight line 5 in FIG. 1B and the two dipole antennas 31 and 32. When the phase shift amount (phase difference) is 60 °, the beam center axis angle becomes almost 30 ° because the distance between the straight line 5 and the dipole antennas 31 and 32 is 0 (that is, the straight line 5).
It is the time of (upper). When the phase shift amount (phase difference) is 65 °,
This is when the distance between the straight line 5 and the dipole antennas 31 and 32 is 0.03λ (4.5 mm) or less. FIG. 7 shows the measurement of the beam width in the horizontal plane. It can be seen from the figure that the beam width is almost 60 ° regardless of the distance between the straight line 5 and the dipole antennas 31 and 32 when the phase difference is 60 ° and 65 °.
Has been obtained. However, as the distance between the straight line 5 and each of the dipole antennas 31 and 32 increases, the difference between the maximum value and the minimum value increases, and the frequency characteristics deteriorate. From the above, the side reflectors T1 = 0.223λ, T2 = 0.
At 453λ, line 5 and dipole antenna 31,
It is considered that each distance from the M.32 to 0.03λ or less is optimal.
T1 = 0.223λ, T2 = 0.453λ, phase shift (phase difference) 60 °, straight line 5 and dipole antennas 31 and 32
FIG. 8 shows a directivity pattern at each distance of 0 from FIG. It can be seen that the central axis is approximately 30 ° and the beam width in the horizontal plane is approximately 60 °.

Next, the width T1 of the side reflector 21 is set to 0.25.
The same measurement was performed for the case of λ (37.5 mm). FIG. 9 is a plot of the beam center axis angle, and FIG. 10 is a plot of the beam width in the horizontal plane. As can be seen from these figures, the beam center width is approximately 30 ° and the beam width is approximately 60 ° because the phase shift amount (phase difference) is 60 °.
In both cases, the phase shift amount (phase difference) is 65 ° when the distance between the straight line 5 and the dipole antennas 31 and 32 is 0 (that is, on the straight line 5). T1 = 0.25λ, T2 =
FIG. 11 shows the directivity pattern when 0.453λ, the phase shift amount (phase difference) is 60 °, and the distance between the straight line 5 and the dipole antennas 31 and 32 is 0. Beam center axis angle is almost 30
°, the beam width in the horizontal plane is approximately 60 °.

From the above, when the optimum values are obtained, the width T1 of the side reflector 21 is 0.2 to 0.25λ, the width T2 of the side reflector 22 is about 0.453λ, and the reflector 1 and the dipole antenna 31 are used. , 32 are equal to the side reflector 2
This is the distance at which the dipole antennas 31, 32 are arranged on the side of the reflection plate from 0 to 0.03λ from the straight line connecting the free ends of 1 and 22. Second Embodiment (Sharing of Configuration Space between Antenna and Antenna Using Another Frequency Band) FIG. 12 shows the configuration space of the antenna device of the first embodiment and the base station antenna device for mobile communication using another frequency band. A configuration example in which a reflector is shared) is shown. A distance D3 from the center of the reflector 1, a dipole antenna 31,
A dipole antenna 33 is placed parallel to 32. In this example, the points where the feeding points of the dipole antennas 31, 32, and 33 are projected on the reflector 1 are arranged at equal intervals on one straight line. As an example, in the case of a base station antenna for mobile communication in the 800 MHz band, the distance between the reflector and the dipole antenna 33 is about 0.25λ (90 mm). The beam width in the horizontal plane of this dipole antenna 33 is about 120 °
It is. Therefore, three antenna devices including the reflector 1 and the dipole antenna 33 are required to cover the 360 ° area.

An antenna device sharing a configuration space, that is, dipole antennas 31 and 32 and dipole antenna 3
Assuming that the antenna device 3 shares the reflector 1 with the side reflectors 21 and 22 as shown in FIG. 13, as shown in FIG. 13A, from the dipole antenna 33 in the direction of arrow 8 (the direction perpendicular to the reflector 1). The beam is emitted at a horizontal beam width of 120 °. From the dipole antennas 31 and 32, the beam width in the horizontal plane is radiated at 60 ° in the direction of arrow 9 (direction of 30 ° with respect to the direction perpendicular to the reflector 1) according to the structural parameters described in the first embodiment. According to the antenna device shown in FIG.
From the dipole antenna 33, the direction of the arrow 8 is the same as that of FIG.
13A, the beam width in the horizontal plane is radiated at 60 ° in the direction of arrow 9 inclined 30 ° to the opposite side to the arrow in FIG. 13A.

The antenna device shown in FIG. 13A and FIG.
The antenna device shown in FIG. 14 is simplified as shown in FIG. FIG. 14A is a perspective view thereof, and FIG. 14B is a plan view seen from above. In this way, the configuration space of the base station antenna can be shared even in mobile communication using different frequencies by one antenna device, and a zone of 120 ° can be covered.

In this embodiment, the dipole antenna 31,
The points where the feed elements 32 and 33 are projected on the reflector 1 are arranged at equal intervals on one straight line.
The dipole antennas 31, 32, and 33 may be vertically shifted so as to be relatively shifted in the vertical direction. Third Embodiment (Zone Configuration Using Antenna Device Sharing Configuration Space) The antenna device integrated by the second embodiment is arranged as shown in FIG. As shown in FIG. 15, six wireless zones A to F each having a sector of 60 degrees each having a range of 360 degrees at equiangular intervals are formed, and a boundary line between adjacent wireless zones is defined as 5 zones.
1AB, 51BC,..., 51FA. The antenna devices 7 shown in FIG. 14 are respectively arranged at positions that are close to every other boundary lines 51FA, 51BC, and 51DE and are separated from the intersections of these boundary lines by an equal distance. The angle between the back of the plate 1 and the boundary line is 30
It is a degree. The main beam radiating direction from each antenna device 7 is indicated by three arrows, followed by a number “8” indicating the main beam direction of the 120 ° beam antenna and a number “9” indicating the main beam direction of the 60 ° beam antenna. , One of the symbols A to F of the wireless zone assigned to the antenna is arranged and attached. Further, if the space diversity system is adopted to improve the communication quality, three receiving antenna devices having the same structure are required. For the sake of explanation, the receiving antenna device for space diversity is denoted by "7 '"(': dash). Numbers “10”, 60 indicating the main beam direction of the 120 ° beam antenna of the antenna device 7 ′
° After the number “11” indicating the main beam direction of the beam antenna, symbols A to
F was placed side by side.

In this case, a total of two antennas, one of the transmitting and receiving antenna devices and one of the receiving antenna devices, are arranged at the same height so that the direction of the main beam is 120 ° in the horizontal plane. Place them close to each other and make them a set.
It will be provided with an angular interval of 20 °. As can be seen from the figure, the mobile communication using the 800 MHz band has a 120 ° 3-sector zone configuration. For example, to cover the total 120 ° zone of the wireless zone A and the wireless zone B, the wireless zone A , B, the 120 ° beam “8AB” of the transmitting / receiving antenna device 7 and the 120 ° beam “10A” of the receiving antenna device 7 ′ located in the wireless zone B are near the boundaries 51FA, 51AB on the opposite sides of each other.
B "enables space diversity reception.

Since the mobile communication using the frequency of the 2 GHz band has a 60 ° 6 sector zone configuration, for example, to cover the wireless zone A, the 60 ° beam “9A” of the transmitting / receiving antenna device 7 in the wireless zone A is used. And wireless zone B
The 60 ° beam “11” of the receiving antenna device 7 ′
A "enables space diversity reception. To cover the wireless zone B, space diversity reception can be performed by the 60 ° beam “9B” of the transmitting / receiving antenna device 7 in the wireless zone A and the 60 ° beam “11B” of the antenna device 7 ′ in the wireless zone B.

As described above, the antenna device in the own zone and the antenna device in the adjacent wireless zone (the one having the antenna device facing in the same direction) have 120
° Covering the zone, 36
Can cover 0 ° zone.

[0024]

As described above, according to the present invention, the widths of the side reflectors provided on both side edges of the reflector are made different, and the distance between the two dipole antennas and the reflector is made different. By combining two radiations with a phase shift amount (phase difference) by a phase shifter, the center axis of the beam is tilted by about 30 ° from the main radiation direction of the reflector and the single dipole antenna. , Beam width in horizontal plane is almost 60
Thus, it is possible to obtain an antenna device having a directivity of.

The required number of antennas can be reduced by sharing the configuration space between the antenna device and the base station antenna device for mobile communication using another frequency band.

[Brief description of the drawings]

FIG. 1 shows an antenna device according to the present invention, wherein A is a perspective view and B is a plan view seen from above.

FIG. 2 is a diagram showing a relationship between a beam center axis angle and T2 of the antenna device according to the present invention.

FIG. 3 is a diagram showing a relationship between a beam width in a horizontal plane and T2 of the antenna device according to the present invention.

FIG. 4 is a diagram showing a relationship between a central axis angle of a beam and T1 of the antenna device according to the present invention.

FIG. 5 is a diagram showing a relationship between a beam width in a horizontal plane and T1 of the antenna device according to the present invention.

FIG. 6 is a diagram showing a relationship between a distance of a dipole antenna with respect to a straight line 5 and a beam center axis angle with respect to a phase difference.

FIG. 7 is a diagram showing the relationship between the distance of the dipole antenna with respect to the straight line 5 and the beam width in the horizontal plane with respect to the phase difference.

FIG. 8 is a diagram showing a horizontal directivity pattern of the antenna device according to the present invention.

FIG. 9 is a diagram showing a relationship between a distance of a dipole antenna with respect to a straight line 5 and a beam center axis angle with respect to a phase difference.

FIG. 10 is a diagram showing the relationship between the distance of the dipole antenna with respect to the straight line 5 and the phase difference and the beam width in the horizontal plane.

FIG. 11 is a diagram showing a directivity pattern in a horizontal plane of the antenna device according to the present invention.

FIG. 12 shows an embodiment of the antenna device according to the present invention used for a plurality of frequency bands, where A is a perspective view and B is a plan view seen from above.

FIG. 13 is a diagram showing directions of main beams in the embodiment shown in FIG. 12;

FIG. 14 is a diagram showing an antenna device in which two antenna devices shown in FIG. 13 are vertically arranged and integrated.

FIG. 15 is a diagram showing an embodiment of a base station antenna device configured as a wireless zone according to the present invention.

FIG. 16 shows a conventional antenna device, wherein A is a perspective view, and B is
Is a plan view seen from above.

17 is a diagram showing a relationship between a phase difference and a beam center axis angle in the antenna device of FIG. 16;

FIG. 18 is a diagram showing a relationship between a beam width and a side lobe level with respect to a phase difference in the antenna device of FIG. 16;

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/36 H04B 7/26 105A

Claims (6)

[Claims] 1. A single rectangular planar reflector and two parallel dipoles facing the reflector, parallel to the side edges thereof, and separated from the reflector by different distances D1 and D2. An antenna, a side reflector connected to both side edges of the reflector, and provided vertically on the same side as the dipole antenna; and a phase shifter provided on a feed line of one dipole antenna, In a base station antenna device that combines the radiation of two dipole antennas with the same amplitude and different phases, a phase shift to the feed line is made from the width T1 of the side reflector close to the dipole antenna where no phase shifter is provided in the feed line. The width T2 of the side reflector close to the dipole antenna provided with the reflector is increased, and the phase shifter is connected to the feed line based on the distance D1 between the dipole antenna and the reflector without the phase shifter provided in the feed line. A base station antenna device, wherein a distance D2 between the provided dipole antenna and the reflector is increased. 2. The base station antenna device according to claim 1, wherein the two dipole antennas are located on a straight line connecting the free ends of the two side reflectors or on the reflector side with respect to the straight line. A base station antenna device. 3. The base station antenna device according to claim 2, wherein the width T1 of one of the side reflectors is 0.2 to 0.25λ (λ is a used radio wave wavelength), and the width T2 of the other side reflector is about 0. .45
The base station antenna device, wherein the 3λ and the two dipole antennas are on the side of the 0 to 0.03λ reflector from a straight line connecting the free ends of the side reflectors. 4. The base station antenna device according to claim 1, wherein a third dipole antenna using a different frequency from the two dipole antennas is on the same side as the two dipole antennas, What is projected on the reflector,
A base station antenna device provided so as to be located between two dipole antennas. 5. The base station antenna device according to claim 4, wherein the antenna device according to claim 4 and an antenna device whose right and left are switched are arranged vertically close to each other. Station antenna device. 6. The base station antenna device according to claim 5, wherein two of the antenna devices according to claim 5 have the same height so that the directions of the main beams are 120 ° in the horizontal plane. A base station antenna apparatus which is arranged in close proximity and two sets of such antenna apparatuses are arranged at an angular interval of 120 ° in a horizontal plane.