JPH05291822A - Antenna system - Google Patents

Abstract

PURPOSE:To obtain the small sized antenna system with a light weight having a small wind receiving area whose in-horizontal plane directivity can be changed without replacement of the element antenna. CONSTITUTION:Radiation elements 17a, 17b of the antenna system 10 having the elements formed on a dielectric board and a reflection plate form a dipole 16 of 1/2 wavelength, the reflection plate 12 is provided upright to the dielectric board 15 in the center of which the radiation elements 17a, 17b are formed, both ends 12a, 12b of the reflection plate are folded toward the board 15 by nearly 45 deg., the dielectric board and the reflection plate are mounted in a cylindrical radome 13 and a couple of reflection rods 14a, 14b are arranged to the outside of the radome 13 in an oblique front direction with respect to the radiation direction of a radio wave by a mount fixture 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device for a base station for land mobile communication used in a car telephone or the like, and more particularly to an antenna device which is small and lightweight and which can change directivity in a horizontal plane.

[0002]

2. Description of the Related Art Conventionally, a frequency of 800 MHz band is used for land mobile communication such as a car telephone, and as a base station antenna, an omnidirectional antenna is arranged above a tower,
Alternatively, a plurality of directional antennas are arranged on the side surface of a steel tower, and by combining them, omnidirectional directional characteristics are obtained.

However, the development of land mobile communication has been remarkable in recent years, and it is expected that a system using the 800 MHz band will not be able to cope with an increase in mobile stations in the near future, especially in a large city, and a new frequency band such as 1. 5 GHz
The shift to obi is being considered.

In contrast to the conventional omni-zone, a zone structure of a 3-sector system or a 6-sector system that can easily cope with an increase in mobile stations is conceivable, and the antenna for the base station also has a 60 degree beam or a 120 degree beam in the horizontal plane Directional antenna is required.

Conventionally, this kind of directional antenna of 60-degree beam or 120-degree beam has a corner reflector antenna as shown in FIGS. 5 (A), (B) and FIGS. 6 (A), (B). Was often used. FIGS. 5 (A) and 5 (B) show an 8-stage dipole antenna device 1 having a directivity of 60 degrees in the horizontal plane in the frequency band of 1.5 GHz, and FIG.
(B) shows an 8-stage dipole antenna device 2 having a directivity of 120 degrees in the horizontal plane.

In the antenna device 1 shown in FIGS. 5A and 5B, a dielectric substrate 3 having a dipole as a radiating element, a radome 4, and feeding points (connectors) 5a and 5b to the radiating element. , The mounting brackets 6a, 6b supporting pillars 7 and:
It is composed of a corner reflector 8 for a 60 ° beam.

The antenna device 2 shown in FIGS. 6A and 6B has the dielectric substrate 3, the radome 4, the feeding points (connectors) 5a and 5b, the fittings 6a and 6b, the support pillars 7 and It is composed of a corner reflector 9 for a 120 ° beam.

[0008]

However, the antenna devices 1 and 2 have the following problems. (1) When changing the directional characteristics in the horizontal plane, refer to FIG.
As shown in FIGS. 6A and 6B and FIGS. 6A and 6B, each beam has an independent antenna, so that all the antennas must be replaced.

(2) The maximum wind-receiving area of the antenna device for a 60-degree beam in the horizontal plane shown in FIGS. 5A and 5B is the maximum in the front direction of the antenna, 0.23 m × 2 m = 0.
It will be 46 m ² . At maximum instantaneous wind speed of 60 m / sec,
0.46 m ² × 2207 N / m ² × 1.8 = 1827.
A wind pressure of 4N is applied (the wind force coefficient of the corner-shaped reflector is 1.8). For this reason, the support pillars are increased in size, and the six-sector base station requires six 60-degree beam antenna devices, which greatly affects the antenna installation capacity of the steel tower.

The present invention has been made in view of the above points,
It is an object of the present invention to solve the above problems and to provide a small and lightweight antenna device for a base station, which has a small wind-receiving area and can change the directional characteristics in the horizontal plane without exchanging the antenna.

[0011]

The structure of the present invention for achieving the above object is as follows in an antenna device having a radiating element formed on a dielectric substrate and a reflecting plate.

(1) In the radiating element, the distance from the reflecting plate in the vertical direction is about 1/4 of the wavelength at its resonance frequency.
Is a half-wave dipole disposed so that the dielectric plate on which the radiating element is formed is erected vertically in the center of the dipole, and both end portions of the dielectric plate are provided. Is formed by bending the dielectric substrate in parallel with the dielectric substrate at an angle of about 45 degrees, and is further mounted in a cylindrical radome.

(2) The antenna device of (1) above is characterized in that a pair of reflecting rods are arranged by a mounting tool outside the cylindrical radome and obliquely forward in the radio wave radiation direction.

(3) The fitting of the reflecting rod in (2) above is characterized by comprising an annular band member and a buckle member so as to be attached to and detached from the cylindrical radome.

[0015]

[Operation] The antenna device configured as described above has a small wind-receiving area and can be made small and lightweight while having directivity of a 120-degree or 60-degree beam in a horizontal plane.

With the directional characteristic in the horizontal plane, it is possible to easily change between the 120 ° and 60 ° beams by attaching and detaching a pair of reflecting rods. In this case, it is possible to reduce the air receiving area of the antenna device in which the directional characteristic in the horizontal plane in which the pair of reflecting rods is arranged is 60 degrees beam as compared with the conventional one.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be illustratively described in detail below with reference to the drawings.

1 (A) and 1 (B) show an embodiment of the antenna device of the present invention, and FIG. 1 (A) shows the antenna device having a 60 degree beam in the horizontal plane in the 1.5 GHz band. A perspective view and FIG. 1B are plan views thereof.

In the figure, an antenna device 10 is mainly composed of two sets of printed antennas 11a and 11b and a reflector 1.
2, a cylindrical radome 13 and a pair of reflecting rods 14a,
14b and.

The two sets of printed antennas 11a and 11a
Each of b is the dipole 1 on both sides of the dielectric substrate 15.
6 are arranged so as to be vertically stacked in four stages.

The radiating elements 17a and 17b forming the dipoles 16 on both surfaces of the dielectric substrate 15 have a frequency f.
Are formed so as to resonate with the radiating elements 17a and 17b.
The distance between the two ends of is equal to about 1/2 of the wavelength λ of the resonance frequency f.

The radiating elements 17a and 17b are half-wavelength dipoles 16 which are formed at right angles to the feed lines 18a and 18b formed on the dielectric substrate 15 in opposite directions.

When the printed antennas 11a and 11b are attached to the reflection plate 12, the distance from the reflection plate 12 to the radiating elements 17a and 17b in the vertical direction is about ¼ of the wavelength λ of the resonance frequency f. Arrange so that

It should be noted that 4 formed on the dielectric substrate 15
Each of the radiating elements 17a, 17b of the stage is combined by a distribution line 19 formed like a tournament combination,
It is connected to the feeding points 20a and 20b.

The reflector 12 is formed by connecting the printed antennas 11a and 11b in series and fixing them to the central portion thereof, and the both ends 12a and 12b of the antennas 11a and 11b are about 30 mm.
It is bent in parallel to the dielectric substrate 15 of 11b and at about 45 ° toward the substrate 15 side.

Then, the printed antennas 11a, 1a
The reflection plate 12 to which 1b is fixed is a cylindrical radome 13
It is installed inside. The cylindrical radome 1 in the figure
The diameter of 3 is about 100 mm.

Further, at a position where both sides 12a, 12b of the reflecting plate 12 are in contact with an extension line of about 70 mm from the bent tip, a pair of reflecting rods 14a, 14b having a diameter of about 20 mm are attached by the fitting 21 to the cylindrical radome. It is attached to and arranged at 13. The mounting member 21 is mainly composed of an annular band member 21a and a buckle member 21b, and has a structure that can be easily attached to and removed from the radome 13.

FIG. 2A shows the antenna device 1 of FIG.
2 is a perspective view when the reflecting rods 14a and 14b of No. 0 and the fitting 21 are removed, and FIG. 2B is a plan view thereof.

FIG. 3 is a view with the reflecting rods 14a and 14b shown in FIG.
In the directional characteristic diagram in the horizontal plane in the 1.5 GHz band of the antenna device of (A), a 60 degree beam is obtained, and the front-back ratio of the directional characteristic is 20 dB or more. FIG. 4 shows a reflector 14
1.5G of the antenna device of FIG. 2 (A) without a and 14b
A 120-degree beam is obtained in the horizontal directional pattern in the Hz band.

As described above, the antenna device 10 has a directivity in the horizontal plane of 6 depending on the presence or absence of the reflecting rods 14a and 14b.
It can be changed to 0 degree and 120 degree beams. Also, since the method can be performed without exchanging all the antennas and particularly without connecting a complicated power feeding cable or the like, it is possible to change the directional characteristic in the horizontal plane without interrupting wireless communication.

Then, as shown in FIGS. 1 (A) and 1 (B),
The maximum wind receiving area of the 60-degree beam antenna device is determined by the cylindrical radome 13 and the reflecting rods 14a and 14b.
The air receiving area of the multi-stage dipole antenna device is (0.1 m × 2 m) + (0.02 m × 2 m × 2) = 0.28 m ² , which is the conventional type shown in FIGS. 6 (A) and 6 (B). 40 compared to
% Can be reduced.

Also, the cylindrical radome 13 and the reflecting rod 14a,
The wind force coefficient of 14b is 1.2 at the maximum, and the wind pressure of the antenna device of the present embodiment is 0.28 m ² × 2207 N / m ² × 1.2 = 741.5 N, which is (741. 5 / 1827.4) x 1
The wind pressure is 00 = 40.5%, and the burden on the supporting columns and steel tower is significantly reduced.

Note that the technique of the present invention is not limited to the technique in the above-described embodiment, and may be implemented by means of another mode that achieves the same function, and the technique of the present invention can be variously modified within the scope of the above configuration. Can be changed or added.

[0034]

As is apparent from the above description, according to the antenna device of the present invention, the dielectric substrate having the ½-wavelength dipole formed as the radiating element is erected vertically on the central portion of the reflector. At the same time, both ends of the reflector are bent toward the dielectric substrate side at an angle of about 45 degrees, and further mounted in a cylindrical radome, so that the beam can be received while directing the beam at 120 degrees in the horizontal plane. The wind area is small, and the size and weight can be reduced.

Further, since a pair of reflecting rods is disposed outside the radome of the antenna device and obliquely forward in the radiation direction of the radio wave, the antenna can be changed to a directivity of a 60 degree beam in a horizontal plane. ..

Therefore, it is possible to easily change the directional characteristics in the horizontal plane without interrupting the wireless communication and without connecting a complicated power supply cable or the like. Further, in the antenna of the horizontal plane 60 ° beam, the wind pressure can be reduced by about 60% as compared with the conventional type, and a small and lightweight antenna device for the base station antenna can be provided. Further, the support pillar to which the antenna is attached can be downsized, and mounting restrictions on a steel tower or the like can be reduced.

[Brief description of drawings]

1 shows an embodiment of an antenna device of the present invention, and FIG.
1A is a partially cutaway perspective view thereof, and FIG. 1B is a plan view thereof.

2A and 2B show an antenna device in which the reflection rod and the mounting bracket of FIGS. 1A and 1B are removed, FIG. 2A being a partially broken perspective view thereof, and FIG. 2B being a plan view thereof. Is.

FIG. 3 is a directional characteristic diagram in the horizontal plane in the 1.5 GHz band of the antenna device (with a reflecting rod) shown in FIGS. 1 (A) and 1 (B).

FIG. 4 is a directional characteristic diagram in the horizontal plane in the 1.5 band of the antenna device (without a reflecting rod) shown in FIGS. 2A and 2B.

5 shows a conventional antenna device, FIG. 5 (A) is a partially broken perspective view thereof, and FIG. 5 (B) is a plan view thereof.

FIG. 6 shows another conventional antenna device, FIG. 6 (A) is a partially cutaway perspective view thereof, and FIG. 6 (B) is a plan view thereof.

[Explanation of symbols]

 10 Antenna Device 11a, 11b Print Antenna 12 Reflector 12a, 12b Reflector Edge 13 Radome 14a, 14b Reflector 15 Dielectric Substrate 16 Dipole 17a, 17b Radiating Element 21 Mounting Bracket 21a Annular Band Member 21b Buckle Member

Claims (3)

[Claims] 1. An antenna device having a radiating element formed on a dielectric substrate and a reflecting plate, wherein the radiating element has a distance in the vertical direction from the reflecting plate of about 1/4 of a wavelength at its resonance frequency. Is a half-wavelength dipole arranged so that the dielectric substrate on which the radiating element is formed is erected vertically at the center of the dipole, and both end portions of the dielectric substrate are An antenna device characterized in that the antenna device is formed in parallel with the dielectric substrate and bent toward the substrate side by about 45 degrees, and is further mounted in a cylindrical radome. 2. An antenna device having a radiating element formed on a dielectric substrate and a reflector, wherein the radiating element has a distance in the vertical direction from the reflector of about 1/4 of a wavelength at its resonance frequency. Is a half-wavelength dipole arranged so that the dielectric substrate on which the radiating element is formed is erected vertically at the center of the dipole, and both end portions of the dielectric substrate are Formed parallel to the dielectric substrate and bent toward the substrate side at an angle of about 45 degrees, and mounted inside a cylindrical radome, and on the outside of the radome, in a diagonally forward direction in the radio wave emission direction. An antenna device in which the reflecting rod of 1 is arranged by a fixture. 3. The antenna device according to claim 2, wherein the fixture for the reflecting rod comprises an annular band member and a buckle member so as to be attached to and detached from the cylindrical radome.