JP3721050B2 - Diversity antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diversity antenna used as a base station antenna in mobile communication using a microcell.
[0002]
[Prior art]
As a conventional base station antenna in mobile communication using a microcell, a horizontal omnidirectional collinear antenna is used. In this case, the collinear antenna has a structure in which the collinear antenna is physically erected in the vertical direction. In the diversity antenna configuration and the array antenna configuration, a plurality of the collinear antennas are used at the same time, and each collinear antenna has a configuration that stands vertically in the vertical direction as shown in FIG. In general, a plurality of collinear antennas are arranged at equal intervals in a horizontal plane.
[0003]
Such an antenna mounting portion has a shape in which the supporting arms 3 are arranged radially at the front ends of the supporting columns 2 and the antenna 1 is attached to the end portions of the supporting arms 3 in the vertical direction. Therefore, the overall structure is square, and the shape is easy to give a sense of pressure visually.
[0004]
[Problems to be solved by the invention]
Base station antennas arranged for providing mobile communication services are places where there are many users, such as residential areas and business districts, and are generally easily noticeable. Furthermore, since it may be attached to a place that can be seen overhead or close to a passer-by or the like such as the upper part of a utility pole, it is necessary to avoid a shape that visually gives a sense of intimidation or instability.
[0005]
An object of the present invention is to provide a diversity antenna that can set the maximum radiation directivity of an antenna in a horizontal direction or a predetermined direction while having a structurally balanced shape.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, in the diversity antenna in which a plurality of antennas are arranged at a predetermined interval, the plurality of antennas have a center line in a vertical direction via a fixture fixed to the tip of one support column. Arranged on an inverted conical surface that opens upward , and each antenna has an array element configuration arranged in the endfire direction. The signal amplitude and phase of each array element are weighted and synthesized, and each antenna is arranged. When the opening angle of the inverted conical surface (inclination angle of each antenna with respect to the vertical direction) is θ, the maximum radiation directivity of each antenna is set to a direction shifted by an angle θ from the broadside direction of the antenna. A synthesis circuit that sets the maximum radiation directivity of each antenna arranged on the surface in the horizontal direction is provided on the part of the fixture or on the support column side.
[0007]
The invention according to claim 2 is a diversity antenna in which a plurality of antennas are arranged at a predetermined interval, and the plurality of antennas has a center line in a vertical direction via a fixture fixed to the tip of one support pillar. It is arranged on an inverted conical surface that opens upward , and each antenna has an array element configuration arranged in the endfire direction, and each element has an element configuration having unidirectionality in two opposite directions. , was synthesized by weighting the amplitude and phase of the signal of each array element, the opening angle of the inverted cone surface (inclination angle of each antenna relative to the vertical direction) is taken as θ that each antenna is arranged, the maximum of each antenna The combined directivity is set so that the radiation directivity is shifted by an angle θ from the broadside direction of the antenna, and the maximum radiation directivity of each antenna placed on the inverted conical surface is set horizontally. The preparation for partial or support pillar-side of the fixture.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a basic configuration of a diversity antenna of the present invention. In the figure, a plurality of antennas 1-1 to 1-6 constituting a diversity antenna are arranged at equal intervals on an inverted conical surface whose center line is open upward in the vertical direction. Each of the antennas 1-1 to 1-6 may take any structure such as a structure in which the entire length functions as an antenna, or a structure in which a part (for example, the upper half) functions as an antenna.
[0009]
FIG. 2 shows the maximum radiation directivity of each antenna. The maximum radiation directivity 4 of each antenna 1-1 to 1-6 is set in a direction shifted by a predetermined angle θ from the broadside direction of the antenna, as shown in FIG. As shown in FIG. 2 (b), this angle θ coincides with the opening angle θ of the inverted conical surface where the antennas are arranged. As a result, when each antenna is arranged on the inverted conical surface, the maximum radiation directivity 4 of each antenna constituting the diversity antenna can be set in the horizontal direction as shown in FIG. it can.
[0010]
By the way, since a portable terminal is generally used at various angles, the polarization of a radio wave arriving at a base station antenna changes according to the inclination of the terminal. Therefore, in the conventional base station antenna set up in the vertical direction, if the incoming polarization is close to the horizontal polarization because the terminal is used at an angle, the reception level may be reduced by about 15 dB at maximum due to the polarization mismatch. is there. On the other hand, the diversity antenna of the present invention is arranged on the conical surface with each antenna inclined by a predetermined angle θ with respect to the vertical direction, so that the effect of polarization diversity can also be obtained and the inclination of the terminal can be obtained. It is possible to improve the reception level drop due to.
[0011]
FIG. 3 shows a first embodiment of the diversity antenna of the present invention. Although the present embodiment shows the case where there are two antennas, the configuration is the same with four or other numbers.
[0012]
In the figure, the diversity antenna of the present embodiment has a configuration in which a bifurcated attachment 5 is fixed to the tip of a support column 2 and one end of the antenna 1 is inserted and fixed in an insertion portion of the attachment 5. The attachment 5 has a pipe shape so that the cable 6 connected to the antenna 1 can pass through, and has a structure in which the inserted antenna 1 is fixed at a predetermined position. Since the number of antennas 1 and the inclination angle are determined by the shape of the fixture 5, the corresponding fixture 5 is used.
[0013]
The diversity antenna according to the present embodiment does not require a brace for vertically supporting each antenna as in the conventional configuration, and has a structure in which the support pillar 2, the fixture 5, and the antenna 1 are integrated. Can reduce the feeling of pressure.
[0014]
FIG. 4 shows a second embodiment of the diversity antenna of the present invention. Although this embodiment also shows a case where there are two antennas, four or other numbers are similarly configured.
[0015]
In the figure, the integrated structure comprising the support pillar 2, the fixture 5, and the antenna 1 constituting the diversity antenna of this embodiment is the same as that of the first embodiment. The feature of this embodiment is that each antenna 1 constituting the diversity antenna has an array element configuration arranged in the end-fire direction, and includes a combining circuit 7 for weighting and combining the amplitude and phase of the signal of each array element. is there. The cable 6 is connected to the synthesis circuit 7.
[0016]
The amplitude / phase of the signal of each array element constituting the antenna 1 is set by the combining circuit 7 so that the maximum radiation directivity is in the horizontal direction, for example. The amplitude and phase values set at this time may be calculated and set in advance with respect to the inclination angle (conical opening angle) θ of the antenna, or the radiation directivity is predetermined by sequentially moving the output signal. It is good also as a structure (adaptive array structure) which performs adaptive control so that it may become the direction of this.
[0017]
FIG. 5 shows a third embodiment of the diversity antenna of the present invention. The feature of this embodiment is that the combining circuit 7 in the second embodiment is installed outside the diversity antenna. That is, the amplitude and phase of the signal of each array element constituting the antenna 1 are set from the synthesis circuit 7 via the cable 2.
[0018]
FIG. 6 shows a fourth embodiment of the diversity antenna of the present invention. Although this embodiment also shows a case where there are two antennas, four or other numbers are similarly configured.
[0019]
In the figure, the integrated structure comprising the support pillar 2, the fixture 5, and the antenna 1 constituting the diversity antenna of this embodiment is the same as that of the first embodiment. A feature of the present embodiment is that each antenna 1 constituting the diversity antenna is configured by a unidirectional antenna 1a facing downward and a unidirectional antenna 1b facing upward. Such an antenna can be realized by, for example, a printed antenna configuration formed on a dielectric substrate.
[0020]
The antennas 1a and 1b are provided with combining circuits 7a and 7b for weighting and combining the amplitudes and phases of the respective antennas and a combining circuit 7c for combining the signals of both antennas. Here, since the antenna 1a is inclined by the angle θ, the tilt angle becomes (θ + θ1) with respect to the horizontal direction by setting the directivity 8a that is further electrically inclined by the angle θ1. In order to set the tilt angle with respect to the antenna 1b, the directivity 8b that is electrically inclined by the angle (2θ + θ1) is set. As a result, both are tilted by (θ + θ1) with respect to the horizontal direction. By setting such a tilt angle, interference between adjacent base stations can be reduced.
[0021]
【The invention's effect】
As described above, the diversity antenna of the present invention has a balanced shape in which a plurality of antennas are radially opened from the upper part of the support column, and can reduce the visual feeling of pressure. In addition, characteristics similar to those of the conventional antenna such as maximum radiation directivity and tilt angle can be ensured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of a diversity antenna of the present invention.
FIG. 2 is a diagram for explaining the maximum radiation directivity of each antenna.
FIG. 3 is a diagram showing a first embodiment of a diversity antenna of the present invention.
FIG. 4 is a diagram showing a second embodiment of the diversity antenna of the present invention.
FIG. 5 is a diagram showing a third embodiment of the diversity antenna of the present invention.
FIG. 6 is a diagram showing a fourth embodiment of the diversity antenna of the present invention.
FIG. 7 is a diagram showing a configuration of a conventional base station antenna.
[Explanation of symbols]
1, 1a, 1b Antenna 2 Support pillar 3 Support arm 4 Maximum radiation directivity 5 Attachment 6 Cable 7, 7a, 7b, 7c Composite circuit 8a, 8b Directivity

Claims (2)

In a diversity antenna in which a plurality of antennas are arranged at predetermined intervals,
The plurality of antennas are arranged on an inverted conical surface whose center line is open upward in the vertical direction via a fixture fixed to the tip of one support column , and each antenna is arranged in the endfire direction. An array element configuration,
When the amplitude and phase of the signal of each array element are weighted and synthesized, and the opening angle of the inverted conical surface on which each antenna is arranged (the inclination angle of each antenna with respect to the vertical direction) is θ, each antenna maximum radiation directivity is set to a direction deviated from the broadside direction of the antenna by an angle theta, wherein the fitting the combining circuit the maximum radiation directivity of the antenna disposed on the opposite conical surface is set to the horizontal direction The diversity antenna is provided on the support pillar side . In a diversity antenna in which a plurality of antennas are arranged at predetermined intervals,
The plurality of antennas are arranged on an inverted conical surface whose center line is open upward in the vertical direction via a fixture fixed to the tip of one support column , and each antenna is arranged in the endfire direction. It is an array element configuration, and each array element is an element configuration having unidirectionality in two opposite directions,
When the amplitude and phase of the signal of each array element are weighted and synthesized, and the opening angle of the inverted conical surface on which each antenna is arranged (the inclination angle of each antenna with respect to the vertical direction) is θ, each antenna maximum radiation directivity is set to a direction deviated from the broadside direction of the antenna by an angle theta, wherein the fitting the combining circuit the maximum radiation directivity of the antenna disposed on the opposite conical surface is set to the horizontal direction The diversity antenna is provided on the support pillar side .

Images