JP4611401B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device, and more particularly, to a technique for improving the isolation between two polarization sharing antennas in an antenna device in which two polarization sharing antennas are arranged with a metal column in between.

For example, in a mobile radio system such as a cellular phone, a method of installing a relay base station is effective as a method for constructing an efficient area in a rural area (local area or small-scale demand density area).
In this case, in the relay base station (direct relay type with the same frequency for transmission and reception), it is necessary to obtain a high relay gain, and in order to suppress oscillation, the antenna for the base station and the mobile station (cellular phone) A high amount of isolation is required between the antenna and the antenna.

As prior art documents related to the invention of the present application, there are the following.
Toshiyuki Maeyama et al., “Development of CDMA cellular repeater with wraparound interference suppression function”, IEICE Journal B Vol.J87-B No.9 pp.1194-1202 September 2004 Takeharu Nara and three others, "Booster Station Low Sidelobe Microstrip Array Antenna Loaded with Choke" (Antenna Propagation Study Group (AP) A ・ P83-4 pp.19-24 April 1983)

Normally, it is possible to improve the isolation characteristics between two antennas by sufficiently separating the distance between the two antennas.
However, in the above-described method, it is necessary to widen the distance between the antenna for the base station and the antenna for the mobile station in the relay base station, and it is difficult to reduce the size of the relay base station.
In order to reduce the size of the relay base station, it is necessary to reduce the distance between the two antennas, the antenna for the base station and the antenna for the mobile station, and then improve the isolation between the two antennas. Necessary.
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide two polarized antennas in an antenna device in which two polarization sharing antennas are arranged across a metal column. It is an object of the present invention to provide a technique capable of improving isolation between wave sharing antennas.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) possess a metal column, the two planar dual-polarized antenna that sandwich the metal column, when the free space wavelength of the central frequency used .lamda.o, the two dual-polarized The distance between the antennas is 0.3λo to 0.5λo, and a vertically polarized radio wave is radiated from one of the two polarization-sharing antennas, and the other of the two polarization-sharing antennas. An antenna device that radiates horizontally polarized radio waves from a dual-polarized antenna, wherein the flat-type dual-polarized antenna has (2 × 2) shared-polarization antenna elements, The shared antenna element has a pair of horizontally polarized half-wave dipole antenna elements and a pair of vertically polarized half-wave dipole antenna elements, and the pair of horizontally polarized half-wave dipole antenna elements and the A pair of vertically polarized half-wave dipoles The antenna elements are arranged in a rectangular shape, and each polarization-sharing antenna element is formed by the pair of horizontally polarized half-wave dipole antenna elements and the pair of vertically polarized half-wave dipole antenna elements. Are arranged such that the center interval of the rectangular shape is 0.6λo to 0.8λo, and the 2 × (2 × 2) horizontally polarized waves of the (2 × 2) shared polarization antenna elements are used. Among the half-wavelength dipole antenna elements, the excitation power of the half-wavelength dipole antenna element for horizontal polarization near the center of the rectangular shape composed of the (2 × 2) polarization-sharing antenna elements is “1”. Then, the excitation power of the half-wave dipole antenna element for horizontal polarization far from the center of the rectangular shape constituted by the (2 × 2) polarization-sharing antenna elements is “0.5”, (2 × 2) polarized antennas Among the 2 × (2 × 2) vertically polarized half-wave dipole antenna elements of the element, the vertical polarization close to the center of the rectangular shape constituted by the (2 × 2) shared polarization antenna elements. When the excitation power of the half-wave dipole antenna element for wave is “1”, the half-wave dipole for vertical polarization far from the center of the rectangular shape composed of the (2 × 2) dual-polarization antenna elements The excitation power of the antenna element is “0.5” .

(2) In (1) , a vertically polarized radio wave is radiated from one of the two polarization-sharing antennas, and horizontally from the other polarization-sharing antenna of the two polarization-sharing antennas. Instead of radiating a polarized wave, a + 45 ° polarized wave is radiated from one of the two polarized antennas and the other polarized antenna of the two polarized antennas is shared. -45 ° polarized waves are radiated from the antenna.
(3) In (1) , a vertically polarized radio wave is radiated from one of the two polarization-sharing antennas, and horizontally from the other polarization-sharing antenna of the two polarization-sharing antennas. Instead of radiating a polarized radio wave, a right-handed or left-handed circularly polarized wave is radiated from each of the two polarization-sharing antennas.
(4) In (3) , an orthogonally circularly polarized radio wave is radiated from one of the two shared antennas and the other shared antenna, or the two shared antennas Radio waves of the same circular polarization are radiated from one of the dual-polarized antenna and the other dual-polarized antenna.

The following is a brief description of effects obtained by the representative aspects of the invention disclosed in the present application.
ADVANTAGE OF THE INVENTION According to this invention, in the antenna apparatus which has arrange | positioned two polarization sharing antennas on both sides of a metal pillar, it becomes possible to improve the isolation between two polarization sharing antennas.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, those having the same function are given the same reference numerals and their repeated explanation is omitted.
FIG. 1 is a perspective view showing an overall configuration of an antenna for a base station and an antenna for a mobile station in a relay base station according to an embodiment of the present invention.
In FIG. 1, 1 is a metal column such as a steel tube column, and 2 and 3 are polarized wave sharing antennas. Here, the dual polarization antenna 2 is an antenna for a base station, and the dual polarization antenna 3 is an antenna for a mobile station (mobile phone). The interval (d1) between the dual-polarized antenna 2 and the dual-polarized antenna 3 is 0.3λo ≦ d1 ≦ 0.5λo. Here, λo is a free space wavelength at the use center frequency.
FIG. 2 is a perspective view for explaining the configuration of the dual polarization antenna 2 (or dual polarization antenna 3) shown in FIG.
As shown in FIG. 2, the dual-polarized antenna 2 (or dual-polarized antenna 3) shown in FIG. 1 has 4 (= 2 × 2) dual-polarization antenna elements (10 ₁ to 10 ₄ ).
Here, the four polarization-sharing antenna elements (10 ₁ to 10 ₄ ) are formed, for example, on the dielectric substrate 11 by using, for example, an etching technique that is a circuit formation technique of a printed wiring board. The reflector has a square shape with a side length (d4) of about 1.6λo. Also, four dual-polarized antenna elements ₍₁₀ 1 to 10 _4), on the dielectric substrate 11, the spacing between centers of dual-polarized antenna elements ₍₁₀ 1 to 10 ₄₎ (d2, d3) is, They are arranged such that 0.6λo ≦ d2 and d3 ≦ 0.8λo.

FIG. 3 is a diagram showing a configuration of the dual-polarized antenna element (10 ₁ to 10 ₄ ) shown in FIG.
As shown in FIG. 3, the dual-polarized antenna element (10 ₁ to 10 ₄ ) shown in FIG. 2 includes a pair of half-wave dipole antenna elements (20, 21) for horizontal polarization and a pair of vertical polarization elements. Half-wave dipole antenna elements (22, 23). The pair of horizontally polarized half-wave dipole antenna elements (20, 21) and the pair of vertically polarized half-wave dipole antenna elements (22, 23) are as shown by the dotted frame in FIG. Arranged to form a square shape.
The center of this square shape is the center of the polarization sharing antenna element (10 ₁ to 10 ₄ ). The length of the pair of horizontally polarized half-wave dipole antenna elements (20, 21) and the pair of vertically polarized half-wave dipole antenna elements (22, 23) is an electrical length of λ. . If the relative dielectric constant of the dielectric substrate 11 is εr, λ can be obtained by λ = λo / (2 × √εr).
FIG. 4 shows the polarization between the pair of half-wave dipole antenna elements (20, 21) for horizontal polarization and the pair of half-wave dipole antenna elements (22, 23) for vertical polarization shown in FIG. It is a graph which shows the amount of coupling | bonding.
From the graph of FIG. 4, between the pair of horizontally polarized half-wave dipole antenna elements (20, 21) and the pair of vertically polarized half-wave dipole antenna elements (22, 23) shown in FIG. It can be seen that the amount of coupling between polarizations is -30 dB or less between 815 MHz and 875 MHz.

In this embodiment, the dual-polarized antenna 2 shown in FIG. 1 radiates horizontally polarized waves (or vertically polarized waves) to the base station antenna, and the dual-polarized antenna 3 shown in FIG. A vertically polarized wave (or horizontally polarized wave) is radiated to the antenna of the mobile station (mobile phone). That is, this embodiment is characterized in that different polarizations are used for wireless communication with a base station antenna and wireless communication with a mobile station antenna.
Further, in this embodiment, as shown in FIG. 5, in the dual-polarized antenna 2 or the dual-polarized antenna 3 shown in FIG. Of the half-wave dipole antenna elements (20, 21) for horizontal polarization, the half for horizontal polarization near the center of a rectangular shape composed of _four polarization-sharing antenna elements (10 ₁ to 10 ₄ ) The excitation power of the wavelength dipole antenna element (half-wave dipole antenna element to which “1” is assigned in FIG. 5) is used for horizontal polarization far from the center of the rectangular shape composed of four polarization-sharing antenna elements. It is larger than the excitation power of the half-wave dipole antenna element (half-wave dipole antenna element given “0.5” in FIG. 5).
In addition, as shown in FIG. 6, in the dual-polarized antenna 2 or the dual-polarized antenna 3 shown in FIG. Among the half-wavelength dipole antenna elements (22, 23), a vertically polarized half-wavelength dipole antenna element close to the center of a rectangular shape composed of _four polarization-sharing antenna elements (10 ₁ to 10 ₄ ). Half-wavelength dipole antenna element for vertical polarization whose excitation power (half-wavelength dipole antenna element to which “1” is assigned in FIG. 6) is far from the center of a rectangular shape composed of four polarization-sharing antenna elements (In FIG. 6, it is larger than the excitation power of the half-wave dipole antenna element to which “0.5” is given). 5 and 6 and FIG. 9 described later, the dielectric substrate 11 is shown by a solid line.
Among the 2 × 4 horizontal polarization and vertical polarization half-wave dipole antenna elements, the horizontal polarization close to the center of the rectangular shape composed of _four polarization antenna elements (10 ₁ to 10 ₄ ) The excitation power of a half-wave dipole antenna element for wave and vertical polarization is greater than the excitation power of a half-wave dipole antenna element for horizontal polarization far from the center of a rectangular shape composed of four polarization-sharing antenna elements. By increasing the size, the side lobes shown in FIGS. 7 and 8 described later can be reduced.

FIG. 7 is a graph showing the directivity characteristics in the horizontal polarization horizontal plane of the dual polarization antenna 2 or the dual polarization antenna 3 shown in FIG. FIG. 8 is a graph showing the directivity characteristics in the vertical polarization horizontal plane of the dual polarization antenna 2 or the dual polarization antenna 3 shown in FIG.
7 and 8, the solid line indicates the horizontal polarization pattern of the main polarization, and the broken line indicates the horizontal polarization pattern of the cross polarization.
From the graphs shown in FIGS. 7 and 8, when the angle is 0 degree, the cross polarization becomes −30 dB or −25 dB or less than the main polarization, and the cross polarization becomes the main polarization. It can be seen that it is greatly attenuated. That is, from the graphs shown in FIGS. 7 and 8, it is possible to greatly attenuate the cross-polarized wave as compared to the main polarized wave not only when the angle is in the 0 degree direction but also in all directions.
Therefore, in this embodiment, for example, by using horizontally polarized radio waves for wireless communication with the base station antenna, and by using vertically polarized radio waves for wireless communication with the mobile station antenna, It is possible to improve the isolation between the dual-polarized antenna 2 and the dual-polarized antenna 3.
In the present embodiment, the dual-polarized antenna 2 or the dual-polarized antenna 3 shown in FIG. 1 has (n × n) shared-polarization antenna elements (10 ₁ to 10), where n is an integer of 2 or more. 10 _n ) may be arranged in a matrix.
Also in this case, among the 2 × (n × n) horizontal polarization and vertical polarization half-wave dipole antenna elements, (n × n) polarization-sharing antenna elements (10 ₁ to 10 _n) The center of the rectangular shape in which the excitation power of the half-wave dipole antenna element for horizontal polarization and vertical polarization near the center of the rectangular shape configured by The excitation power of the half-wave dipole antenna element for horizontal polarization and vertical polarization far from the center is set larger.
For example, as shown in FIG. 9, when (3 × 3) shared polarization antenna elements (10 ₁ to 10 ₉ ) are arranged in a matrix, half horizontal polarization and vertical polarization half-waves are used. Excitation power of 1 is applied to the wavelength dipole antenna element, and then is applied to the half-wave dipole antenna element for horizontal polarization and vertical polarization close to the central half-wave dipole antenna element for horizontal polarization and vertical polarization. the excitation power of 5, the half-wave dipole antenna element for horizontal polarization and vertical polarization near the half-wave dipole antenna element for horizontal polarization and vertical polarization to the next, the excitation power of 0.25, most central The excitation power of 0.125 is supplied to the half-wavelength dipole antenna element for horizontal polarization and vertical polarization far from the half-wavelength dipole antenna element for horizontal polarization and vertical polarization.

In this embodiment, as shown in FIG. 10, by using a 180 ° hybrid circuit (HYB), + 45 ° polarization (or −45 ° polarization) from the polarization sharing antenna 2 shown in FIG. It is possible to radiate −45 ° polarized (or + 45 ° polarized) radio waves from the dual polarization antenna 3 shown in FIG.
Similarly, as shown in FIG. 10, by using a 90 ° hybrid circuit (HYB), a right-handed or left-handed circularly polarized wave is transmitted from the dual-polarization antenna 2 and the dual-polarization antenna 3 shown in FIG. Can be emitted.
Thereby, in the case where the relay base station is operated in the modified examples as shown in FIG. 11 and FIG. 17 described later, the polarization plane is changed, and the isolation between the dual-polarization antenna 2 and the dual-polarization antenna 3 is performed. Can be adjusted. In order to secure the amount of isolation, when using circularly polarized waves, if it is desired to preferentially suppress direct coupling, the orthogonally polarized waves (right- If you want to preferentially suppress the first reflected wave from the surroundings by radiating the left, left-right) radio wave, the same circularly polarized wave (right-right, right-right, It is desirable to radiate left-to-left radio waves.

[Modification 1]
FIG. 11 is a perspective view showing the overall configuration of Modification Example 1 of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
In the modification shown in FIG. 11, the dual-polarized antenna 2 and the dual-polarized antenna 3 are not arranged back to back, but the dual-polarized antenna 2 and the dual-polarized antenna 3 are positioned vertically with the metal column 1 in between. It is arranged in.
[Modification 2]
FIG. 12 is a perspective view showing an entire configuration of a second modification of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
The modification shown in FIG. 12 is a modification of the modification shown in FIG. 11 in which the polarization sharing antenna 3 is tilted downward so that the radio wave radiated from the polarization sharing antenna 3 faces downward.
[Modification 3]
FIG. 13 is a perspective view showing an overall configuration of a third modification of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
The modification shown in FIG. 13 is obtained by changing the direction of the radio wave radiated from the polarization sharing antenna 3 by rotating the polarization sharing antenna 3 left and right in the modification shown in FIG.

[Modification 4]
FIG. 14 is a perspective view showing the overall configuration of Modification 4 of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
The modification shown in FIG. 14 employs a sector shared polarization antenna 4 instead of the planar shared polarization antenna 3 in the modification shown in FIG.
FIG. 15 is a diagram showing an example of the polarization sharing antenna 4 shown in FIG.
The dual-polarized antenna 4 shown in FIG. 15 has a configuration in which a half-wave dipole antenna element 30 for horizontal polarization and a half-wave dipole antenna element 31 for vertical polarization are vertically arranged on a dielectric substrate 12. Is done. In FIG. 15, reference numeral 13 denotes a reflector.
Even with such a configuration, the isolation between the dual-polarized antenna 2 and the dual-polarized antenna 4 can be further improved.
[Modification 5]
FIG. 16 is a perspective view showing an overall configuration of a fifth modification of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
In the modification shown in FIG. 16, the dual-polarized antenna 4 is tilted downward in the modified example shown in FIG. 14 so that the radio wave radiated from the dual-polarized antenna 4 faces downward.
[Modification 6]
FIG. 17 is a perspective view showing the overall configuration of Modification 6 of the antenna for the base station and the antenna for the mobile station in the relay base station according to the embodiment of the present invention.
The modification shown in FIG. 12 is a modification of the modification shown in FIG. 14 in which the dual-polarized antenna 4 is rotated left and right to change the direction of the radio wave radiated from the dual-polarized antenna 4.

In the above description, the case where different polarizations are used for wireless communication with the base station antenna and wireless communication with the mobile station antenna has been described. If the amount of isolation with the shared antenna 3 can be ensured, it is not always necessary to use different polarized waves for wireless communication with the base station antenna and wireless communication with the mobile station antenna. .
For example, if one of the dual-polarized antennas is changed or the operational installation conditions such as changing the radiation direction of the dual-polarized antennas are changed, the plane of polarization is changed to share the polarization with the dual-polarized antenna 2 When adjusting the amount of isolation between the antenna 3 and the radio wave radiated from the dual-polarized antenna 2, vertical polarization, horizontal polarization, + 45 ° polarization, −45 ° polarization, or right Either a circular or left-handed circularly polarized wave is adopted, and the radio wave radiated from the dual-polarized antenna 3 is a vertically polarized wave, a horizontally polarized wave, a + 45 ° polarized wave, a −45 ° polarized wave, or a right-handed or Any of left-handed circularly polarized waves can be adopted.
As mentioned above, the invention made by the present inventor has been specifically described based on the above-described embodiment. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.

It is a perspective view which shows the whole structure of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a perspective view for demonstrating the polarization sharing antenna structure shown in FIG. FIG. 3 is a diagram illustrating a configuration of a polarization sharing antenna element illustrated in FIG. 2. 4 is a graph showing the amount of coupling between polarized waves between the pair of horizontally polarized half-wave dipole antenna elements shown in FIG. 3 and the pair of vertically polarized half-wave dipole antenna elements. FIG. 3 is a diagram for explaining a state in which horizontally polarized excitation power is supplied in the dual-polarized antenna shown in FIG. 1. FIG. 3 is a diagram for explaining a state in which horizontally polarized excitation power is supplied in the dual-polarized antenna shown in FIG. 1. It is a graph which shows the directional characteristic in the horizontal polarization horizontal plane of the polarization sharing antenna shown in FIG. It is a graph which shows the vertical polarization horizontal plane directivity characteristic of the polarization sharing antenna shown in FIG. It is a figure which shows the structure of the modification of the polarization polarized antenna element of the Example of this invention. FIG. 2 is a diagram for explaining a configuration for radiating ± 45 ° polarized radio waves or right / left-hand circularly polarized radio waves from the dual-polarized antenna shown in FIG. 1. It is a perspective view which shows the whole structure of the modification 1 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a perspective view which shows the whole structure of the modification 2 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a perspective view which shows the whole structure of the modification 3 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a perspective view which shows the whole structure of the modification 4 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a figure which shows an example of the polarization sharing antenna shown in FIG. It is a perspective view which shows the whole structure of the modification 5 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations. It is a perspective view which shows the whole structure of the modification 6 of the antenna for base stations in the relay base station of the Example of this invention, and the antenna for mobile stations.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal pillar 2,3, 4 Polarization shared antenna 10 _{1-10 9} Polarization shared antenna element 11,12 Dielectric substrate 13 Reflector 20,21,30 Half wavelength dipole antenna element 22,23 for horizontal polarization 31 Half-wave dipole antenna element for vertical polarization HYB hybrid circuit

Claims (4)

Metal pillars,
Have a dual-polarized antenna of the two planar that sandwich the metal column,
When λo is a free space wavelength of the use center frequency, the interval between the two polarization sharing antennas is 0.3λo to 0.5λo,
An antenna that radiates vertically polarized radio waves from one of the two shared antennas and radiates horizontal polarized waves from the other shared antenna of the two polarized antennas A device ,
The planar type dual polarization antenna has (2 × 2) dual polarization antenna elements,
Each polarization-sharing antenna element is a pair of half-wave dipole antenna elements for horizontal polarization,
Having a pair of vertically polarized half-wave dipole antenna elements,
The pair of horizontally polarized half-wave dipole antenna elements and the pair of vertically polarized half-wave dipole antenna elements are arranged in a rectangular shape,
Each of the dual-polarized antenna elements has a rectangular center distance formed by the pair of horizontally polarized half-wave dipole antenna elements and the pair of vertically polarized half-wave dipole antenna elements of 0. Arranged to be 6λo to 0.8λo,
Among the 2 × (2 × 2) half-wave dipole antenna elements for horizontal polarization of the (2 × 2) dual-polarization antenna elements, the (2 × 2) dual-polarization antenna elements When the excitation power of the half-wave dipole antenna element for horizontal polarization near the center of the rectangular shape constituted by “1” is “1”, the rectangular shape constituted by the (2 × 2) polarization-sharing antenna elements The excitation power of the half-wave dipole antenna element for horizontal polarization far from the center of the
Of the 2 × (2 × 2) vertically polarized half-wave dipole antenna elements of the (2 × 2) polarized antenna elements, the (2 × 2) polarized antenna elements When the excitation power of the half-wavelength dipole antenna element for vertical polarization close to the center of the rectangular shape constituted by “1” is “1”, the rectangular shape constituted by the (2 × 2) polarization-sharing antenna elements The excitation power of the half-wave dipole antenna element for vertical polarization far from the center of the antenna device is “0.5” . Instead of radiating vertically polarized radio waves from one of the two shared antennas and radiating horizontally polarized waves from the other shared antenna of the two shared antennas In addition, a + 45 ° -polarized radio wave is radiated from one of the two dual-polarized antennas, and a −45 ° -polarized wave is emitted from the other dual-polarized antenna of the two dual-polarized antennas. The antenna device according to claim 1 , wherein the antenna device radiates radio waves. Instead of radiating vertically polarized radio waves from one of the two shared antennas and radiating horizontally polarized waves from the other shared antenna of the two shared antennas The antenna device according to claim 1 , wherein a radio wave having a right-handed or left-handed circular polarization is radiated from each of the two polarization sharing antennas. Radiating orthogonally circularly polarized radio waves from one of the two shared antennas and the other shared antenna, or one of the two shared antennas 4. The antenna device according to claim 3 , wherein a radio wave having the same circular polarization is radiated from the other polarization sharing antenna.

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