JPH10174160A - Array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the followup/interference removal characteristics of adaptive array antenna system while suppressing rapid reduction in element directivity at a sector terminal by setting the directivity of respective element antennas for array antenna, which is arranged one by one for each of plural sectors to be used for the adaptive array antenna, wider than a sector angle. SOLUTION: When the followup/interference removal characteristics of adaptive array antenna system using the array antenna having element directivity are found, while setting the front direction perpendicular to its lengthwise direction to 0 deg. and defining the angle width of interference removal disability caused by an interference station as an inhibit area, the more that angle width is narrowed, the more the resolution of antenna system is improved so that followup/interference removal characteristics can be improved. Since the relation between the element antenna directivity and the sector angle is set so as to narrow the angle width of inhibit area, by setting element antenna directivity 2 to 120 deg. and narrowing a sector angle 4-4 to 90 deg., for example, such characteristics can be realized and the local dispersion of quality is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna (not including an adaptive processing circuit) used in an adaptive array antenna apparatus (including an adaptive processing circuit) for a base station for automobiles and cellular phones. .

[0002]

2. Description of the Related Art It is expected that an adaptive array antenna device will be introduced into a base station for automobiles and cellular phones to increase the line capacity. In this case, an array antenna having a plurality of element antennas is installed. There is a need. At this time, in a cell configuration in which each base station has a plurality of sectors, it is necessary to install an array antenna for each sector.

A number of studies have been made on an adaptive array antenna device having an element antenna having omnidirectionality in a horizontal plane (hereinafter referred to as omnidirectionality). However, the influence of the directivity of the element antenna has been considered. The configuration of the array antenna is not disclosed. Conventionally, for example, an array antenna having a 120 ° element directivity for a 120 ° sector and an array antenna having a 60 ° element directivity for a 60 ° sector are used. It was common that

As an example, FIG. 4 shows a case where four element array antennas 1a, 1b and 1c having an element directivity of 120 ° are arranged in 120 ° -3 sectors. In this setting, the tracking / interference elimination characteristics in the front direction perpendicular to the longitudinal direction of each array antenna are secured, but the characteristics are degraded as approaching the sector end 4, and as a result, the line capacity is not increased. Was. On the other hand, it is impossible to make the element antenna directivity omni-directional because the rear surface also has a gain under the condition of the sector configuration. Conversely, when the directivity of the element antenna is reduced, the directivity of the element drops sharply even if the element antenna is slightly displaced from the front, and the above-mentioned characteristic is remarkably deteriorated at the sector end 4.

As described above, at present, a useful configuration using an element antenna having directivity as an array antenna used in an adaptive array antenna device has not been clearly disclosed.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the conventional array antenna which sets the directivity of the element antenna at the same angle as the set sector angle, the element directivity sharply decreases when approaching the sector end, It is an object of the present invention to solve the drawback that the tracking / interference elimination characteristics of an adaptive array antenna device using this array antenna are significantly deteriorated.

[0007]

The present invention is used in an adaptive array antenna device, and in an array antenna arranged one for each of a plurality of sectors, the directivity (angular width) of the element antenna is determined by the sector angle. It is set widely.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in order to clarify the above problems, tracking and interference elimination characteristics of an adaptive array antenna apparatus using an array antenna having all element directivities were obtained by computer simulation. The result is shown in FIG. The horizontal axis is the direction θ where the desired station exists.
And the front direction perpendicular to the longitudinal direction of the array antenna is 0 °. The vertical axis is the angle width A in which the interference from the interfering station cannot be removed when the adaptive array antenna device tracks the desired station, and is referred to as a prohibited area. In this prohibited area, if an interference station exists within the angular width A, it means that the signal received by the antenna falls below a certain reference quality. As this value is smaller, the resolution of the adaptive array antenna device is improved and the tracking / interference elimination characteristics are improved. Element antenna directivity (angle width) φ is 60 as a parameter
°, 90 °, 120 ° and 180 ° are shown.

From the figure, it can be seen that the forbidden area Ao in the front direction is narrow regardless of the directivity of the element antenna. However, as the direction θ of the desired station shifts from the front,
The prohibited area A gradually expands. The desired station direction θ is a half sector angle of the directivity of each element antenna (1/3 of the conventional sector angle).
(Equal to 2), the prohibited area A becomes considerably large at points Pa, Pb, and Pc, and the tracking / interference elimination characteristic deteriorates remarkably. When θ reaches a certain critical angle, the prohibited area A becomes 3
60 °, which indicates that the tracking / interference elimination function is lost. Further, if the desired station direction θ is the same, it can be understood that the prohibited area A is narrower as the element antenna directivity is wider.

As a result of the above study, if the relationship between the element antenna directivity and the sector angle is set to a condition such that the prohibited area A becomes narrow, communication can be performed even at the end of the sector area with less deterioration of tracking and interference removal characteristics. It turns out that it becomes possible. In order to solve the above-mentioned problems, the present invention enables tracking and interference removal even at the sector end 4 by installing an array antenna having an element antenna directivity φ wider than a set sector angle.

FIG. 1 shows the configuration of an embodiment of the present invention. FIG. 1 shows a case of a configuration of a 90 ° -4 sector 120 ° -4 element array antenna for explanation. This configuration is
In FIG. 3A, it corresponds to point Qa. That is, the element antenna directivity φ = 120 ° is the same as the conventional one, the desired station direction θ at the sector end, that is, the half sector angle is 45 °,
Therefore, by making the sector angle narrower than the conventional 120 ° to 90 °, the forbidden area A is narrowed, and the tracking / interference elimination characteristics are improved.

FIG. 2 shows the configuration of another embodiment of the present invention.
Here, for the sake of explanation, 120 ° -3 sectors 180 °-
The case of a configuration of a four-element array antenna is shown. This configuration corresponds to the point Qb in FIG. That is,
The sector angle is 120 ° as in the prior art. Therefore, the desired station direction θ at the sector end, that is, the half sector angle is set to 60 °, and the forbidden area A is narrowed by increasing the element antenna directivity φ from the conventional 120 ° to 180 °. As a result, the tracking and interference removal characteristics are improved.

[0013]

According to the present invention, the directivity (angular width) of each element antenna constituting the array antenna is set to be wider than the sector angle. However, the conventional disadvantage that the tracking / interference elimination characteristics of the adaptive array antenna apparatus are significantly deteriorated is eliminated.

If the array antenna according to the present invention is used in an adaptive array antenna device, the variation in quality within a sector can be reduced, and the channel capacity can be greatly increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing the arrangement and directivity of a 90 ° -4 sector, 120 ° -4 element array antenna of the present invention.

FIG. 2 is a diagram showing the arrangement and directivity of a 120 ° -3 sector, 180 ° -4 element array antenna of the present invention.

FIG. 3 (a) shows the relationship between the interference wave directivity prohibited area (angular width) A of the multi-element array antenna and the desired station direction θ when the front direction of the array antenna is set as a reference (0 °). FIG. 4B is a graph for explaining an area where an array antenna has no directivity to interference waves.

FIG. 4 is a diagram showing the arrangement and directivity of a conventional 120 ° -3 sector, 120 ° -4 element array antenna.

Claims (1)

[Claims] 1. An array antenna for use in an adaptive array antenna device, wherein one array antenna is provided for each of a plurality of sectors, wherein the directivity (angular width) of an element antenna is set wider than a sector angle. Array antenna.