JPH09232850A - Antenna for mobile radio communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the antenna adaptive to outdoor installation by covering a dipole antenna and a parasitic element with a cylindrical radome to improve the weather resistance and the mechanical strength. SOLUTION: An FRP made cylindrical radome 7 covering a dipole antenna 6 is made up of a ceiling cover 7a, a bottom cover 7b and a side wall 7c. The radome bottom cover 7b is adhered to the shell 5a of a feeding connector 5 by adhesives. A groove is made along an outer circumference of the radome ceiling cover 7a and the radome bottom cover 7b respectively and the air- tightness of the radome is improved by inserting an upper end and a lower end of the radome side wall 7c to the grooves. Then a groove 7d is made to the center of the radome ceiling cover 7a and a tip of an antenna element 3 is inserted to the groove 7d to support the dipole antenna 6. A copper plate 8 is adhered to the inner side of the radome side wall 7c with adhesives and the copper plate 8 acts like a parasitic element to decide the directivity of the antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a base station antenna used in mobile radio.

[0002]

2. Description of the Related Art As a base station antenna for mobile radio or the like, a dipole antenna having a structure called a sleeve antenna is mainly used. The conventional antenna is disclosed in JP-A-4-3.
It is disclosed in Japanese Patent Publication No. 29097 and has a structure as shown in FIG. That is, the antenna element 101 in which the inner conductor of the coaxial feed line 103 is extended upward by about 1/4 wavelength from the upper end of the outer conductor, and the 1/4 of which the one end is connected to the upper end of the outer conductor and is covered outside the coaxial feed line. The dipole antenna 104 is formed by the wavelength metal pipe 102, and the supporting jig 10 is attached to the metal pipe 102.
6 is configured to support the parasitic element 105.

[0003]

Since the antenna can set the directional pattern in any direction by the parasitic element, it is useful, for example, when it is placed indoors and covers only the range of a specific direction. It becomes a base station antenna. However, since the dipole antenna and the parasitic element are exposed in the above-mentioned configuration, they are insufficient in weather resistance and mechanical strength when placed outdoors. In addition, this configuration requires a jig for supporting the parasitic element, which causes a problem in that it takes time to manufacture.

[0004] The present invention is to solve the above problems,
The purpose of the present invention is to improve weather resistance and mechanical strength and to realize a mobile radio antenna with a simple structure and easy to manufacture.

[0005]

In order to solve the above problems, a mobile radio antenna according to the present invention comprises a coaxial feed line, at least one dipole antenna fed by the coaxial feed line, and the vicinity of the dipole antenna. And a cylindrical radome that covers the dipole antenna and the parasitic element, and the radome supports the parasitic element.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention includes a coaxial feed line, at least one dipole antenna fed by the coaxial feed line, and at least one dipole antenna disposed near the dipole antenna. A mobile radio antenna, comprising a parasitic element, a cylindrical radome covering the dipole antenna and the parasitic element, and supporting the parasitic element by the radome. The invention according to claim 2 is
The dipole antenna according to claim 1, wherein the dipole antenna is an antenna element in which an inner conductor of the coaxial feed line is extended upward by about ¼ wavelength from an upper end of the outer conductor, and one end is connected to an upper end of the outer conductor to be placed outside the coaxial feed line. It is characterized by comprising a covered 1/4 wavelength sleeve-shaped metal pipe, and the invention according to claim 3 of the present invention is the parasitic element according to claim 1 or 2. Is a metal body fixed to the wall surface of the radome, and the invention according to claim 4 of the present invention is the same as claim 1 or 2, wherein the parasitic element is formed integrally with the radome. The invention according to claim 5 of the present invention is characterized in that it is a metal body.
The parasitic element is a metallic body formed by printing on the wall surface of the radome, and the invention according to claim 6 of the present invention is characterized in that the parasitic element is the radome. The present invention according to claim 7 of the present invention is characterized in that, in claim 1 or 2, the parasitic element is formed by printing. It is characterized in that it is constituted by fixing a resin film having a metal body to the inner wall surface of the radome. The invention according to claim 8 of the present invention is the parasitic element according to claim 1 or 2. Is formed by fixing a resin film having a metal body formed by plating to the inner wall surface of the radome, and the invention according to claim 9 of the present invention is In any one of al 8,
A groove is provided inside the canopy of the radome, and the tip of the dipole antenna is inserted into the groove.

In the above structure, by covering the dipole antenna and the parasitic element with the cylindrical radome, the weather resistance and the mechanical strength are improved, and it is suitable for outdoor placement, and the radome does not feed the power. By supporting the element, it is possible to realize a mobile radio antenna with a simple structure that does not require a dedicated support jig and is easy to manufacture. Furthermore, a groove is provided inside the radome canopy, and the tip of the dipole antenna is inserted into the groove to support the dipole antenna by the radome and prevent characteristic changes due to displacement of the dipole antenna and the parasitic element.

(First Embodiment) FIG. 1 shows a mobile radio antenna according to a first embodiment of the present invention.
(A) is a top view and (b) is a side view. In FIG. 1, 1 is a coaxial feed line, 2 is a brass metal pipe of about 1/4 wavelength, 3 is an inner conductor of the coaxial feed line 1 and an upper end 1 of an outer conductor.
It is an antenna element extended by about ¼ wavelength from a. One end 2a of the metal pipe 2 is connected to the upper end 1a of the outer conductor of the coaxial feed line, and the other end 2b of the metal pipe 2 is connected.
A spacer 4 made of Teflon is inserted and supported between the coaxial feed line 1 and the coaxial feed line 1. The dipole antenna 6 is configured by the above configuration. At the lower end 1b of the coaxial feeder line 1,
A coaxial connector 5 is provided for connecting to an external circuit. Reference numeral 7 denotes a FRP cylindrical radome that covers the dipole antenna 6. The radome 7 is composed of a canopy 7a, a bottom cover 7b, and a side wall 7c. The radome bottom cover 7b is fixed to the shell 5a of the power supply connector 5 with an adhesive. Radome canopy 7a and radome bottom cover 7
Each of the grooves b is provided along the outer circumference,
By inserting the upper end and the lower end of the radome side wall 7c into these, the tightness of the radome is improved. Further, a groove 7d is provided at the center of the radome canopy 7a,
The tip of the antenna element 3 is inserted into the groove 7d to support the dipole antenna 6. A copper plate 8 is fixed to the inside of the radome side wall 7c with an adhesive, and the copper plate 8 functions as a parasitic element to determine the directivity of the antenna.

The antenna element 3 has a diameter of 2 mm, the metal pipe 2 has a diameter of 8 mm, and each has a length of 35 mm, both of which are 1/2 at a frequency of 1.9 GHz.
The wavelength dipole antenna 6 is formed. The copper plate 8, which is a parasitic element, controls the directional characteristics of the horizontal plane by its length, and serves as a reflector when the length is longer than ½ wavelength and when it is shorter than ½ wavelength. Operates as a director. Furthermore, the distance between the copper plate 8 and the center of the dipole antenna 6 is a factor that determines the input impedance.
The impedance increases with distance. In this embodiment, the radome 7 has an inner diameter of 30 mm, and the distance between the copper plate 8 and the center of the dipole antenna 6 is 1.
It was set to 5 mm. The groove portion 7d provided on the radome canopy 7a has a depth of 6 mm and a diameter of 2.2 mm, and the tip portion of the antenna element 3 is inserted therein to support the dipole antenna 6. This prevents the distance between the copper plate 8 and the dipole antenna 6 from changing due to external impact or gravity.

The characteristics of the mobile radio antenna having the above configuration will be described below. Figure 2 shows a copper plate 8 with a length of 80m.
It is a characteristic view which shows the directional characteristic of an antenna in case m, width is 2 mm, and thickness is 0.2 mm. The xyz axes are based on FIG. As can be seen from FIG. 2, the horizontal plane (xy
The (plane) directional characteristic has a pattern in which sectors are formed in the −x direction. That is, the copper plate 8 functions as a parasitic element, and the directional characteristic of the horizontal plane can be controlled by its length. In the case of the dimensions shown in the above embodiment,
Since the parasitic element is longer than ½ wavelength, the parasitic element operates as a reflector. Further, when the parasitic element is shorter than 1/2 wavelength, the parasitic element operates as a director, and has a sectorized pattern in the + x direction where the copper plate 8 is present. These features should be used properly according to the application.

With the structure of the present invention, the copper plate 8 as a parasitic element is supported by the radome 7, thereby protecting the dipole antenna 6 and the copper plate 8 and supporting the parasitic element. It is possible to realize a mobile radio antenna that has a simple structure that does not require, and that can be placed outdoors and that is easy to manufacture.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
3 is a side view showing the mobile radio antenna of the embodiment of FIG.
The present embodiment is different from the first embodiment in that the second dipole antenna 1 is provided below the first dipole antenna 9.
0 and the third dipole antenna 11 below
That is, a collinear array antenna configured by arranging

In FIG. 3, the first dipole antenna 10 has the same structure as that of the first embodiment. Also, the second and third dipole antennas 10 and 1
1 is configured as follows. That is, a circular slit 12x having a width of 3 mm is provided at a predetermined position of the outer conductor of the coaxial feeder 12 as a feeding point, and a pair of quarter-wave metal pipes are provided on the outer conductors of the coaxial feeder on both sides of the circular slit 12x. 13 are opposed to each other and one end of each is connected.
Here, each metal pipe 13 is the same as the metal pipe 2 in the first embodiment, and its open end is supported by the coaxial feeder 12 by the Teflon spacer 14. The radome 15 is a FRP cylinder that covers the first to third dipole antennas 9 to 11, and the inner wall thereof has the first to third dipole antennas 9 to 1.
The copper plates 16 that are juxtaposed to each one are fixed by an adhesive. Further, similarly to the first embodiment, the canopy of the radome 15 and the radome bottom cover are provided with grooves along the outer circumference, respectively, and these are provided in the radome 15.
The upper and lower ends of the side wall of the radome are inserted to improve the hermeticity of the radome. Further, a groove is provided at the center of the canopy of the radome 15, and the tip of the first dipole antenna is inserted therein. Has been supported.

The directional characteristics of the mobile radio antenna having the above configuration will be described below. FIG. 4 is a characteristic diagram showing the directional characteristics of the antennas when the distance between the feeding points of the first to third dipole antennas 9 to 11 is 91 mm. The xyz axes are based on FIG. 3, and the length of the copper plate 16 is
The width and thickness are 80 mm, 2 mm, and 0.2 mm, respectively. As can be seen from FIG. 4, the maximum gain direction of the vertical planes (yz plane and zx plane) is tilted downward, and the tilt angle thereof is approximately 15 degrees. Since the distance between the feeding points is shorter than one wavelength, the maximum gain direction is tilted downward as shown in FIG. Further, when the distance between the feeding points is longer than one wavelength, the maximum gain direction is tilted upward, and when the distance between the feeding points is as long as one wavelength, the maximum gain direction is horizontal. Become. That is, the maximum gain direction of the vertical plane can be controlled by the distance between the feeding points. This is because the phase of the radio wave emitted from each dipole antenna changes depending on the relationship between the distance between the feeding points and the wavelength of the radio wave in the feeding line. These features should be used properly according to the application. As in the first embodiment, the copper plate 16 functions as a parasitic element and the directional characteristic of the horizontal plane (xy plane) is a sectorized pattern.

As described above, when a collinear array is composed of a plurality of dipole antennas, the copper plate 16 functions as a parasitic element and can control the directional characteristic of the horizontal plane. Furthermore, it is possible to control the directional characteristics of the vertical plane depending on the distance between the feeding points of the dipole antennas.

With the configuration of the present invention, the copper plate 16 which is a parasitic element is supported by the radome 15, which protects the first to third dipole antennas 9 to 11, and It is possible to realize a mobile radio antenna that has a simple structure that does not require a power feeding element support jig, can be placed outdoors, and is easy to manufacture.

In the first and second embodiments of the present invention, the parasitic element is constituted by the copper plate 8 (or 16) fixed to the inner wall of the radome 7 (or 15) with an adhesive. Alternatively, the parasitic element may be formed integrally with the radome, or by forming conductive ink on the inner wall surface by transfer printing, or by using a metal body having the printed pattern surface plated with metal. I don't care. Furthermore, even if a metal body printed or plated on a flat resin film is fixed to the inner wall surface of the radome together with the resin film, the same function as when printing directly on the wall surface can be realized. There is an advantage that an inexpensive construction method can be applied. In these cases, there is an advantage that a plurality of parasitic elements can be collectively formed and the dimensional accuracy is improved.

In the first and second embodiments of the present invention, one parasitic element is arranged in the dipole antenna, but a plurality of parasitic elements may be arranged in addition to this. In this case, it is possible to form a more specific directional pattern.

Further, in the second embodiment of the present invention, the number of elements of the dipole antennas 9 to 11 forming the collinear array antenna is three, but other numbers of elements may be used. For example, the maximum gain of the collinear array can be improved by increasing the number of elements.

The numerical values and configurations described in the above embodiments are examples, and the present invention is not limited to the details of these numerical values and configurations.

[0021]

As described above, the mobile radio antenna of the present invention has a weather resistance by covering the dipole antenna and the parasitic element with a cylindrical radome in the structure described in claim 1 and the accompanying claims. The mechanical strength and mechanical strength are improved, and it is suitable for outdoor placement. By supporting the parasitic element with the radome, no special support jig is required, and the structure is easy to move with ease. It is possible to realize a wireless antenna. Further, a groove is provided inside the radome canopy, and the tip of the dipole antenna is inserted into the groove to support the dipole antenna by the radome and prevent characteristic changes due to displacement.

[Brief description of drawings]

FIG. 1A is a top view of a mobile radio antenna according to a first embodiment of the present invention, and FIG. 1B is a side view of the same.

2 (a) to 2 (c) are characteristic diagrams showing the same directional characteristics.

FIG. 3 is a side view of a mobile radio antenna according to a second embodiment of the present invention.

FIGS. 4A to 4C are characteristic diagrams showing the directional characteristics of the same.

FIG. 5 is a perspective view of a conventional mobile radio antenna.

[Explanation of symbols]

 1 Coaxial feeding line 1a Coaxial feeding line Upper end of outer conductor 1b Coaxial feeding line lower end 2 Metal pipe 2a One end of metal pipe 2b Other end of metal pipe 3 Antenna element 4 Spacer 5 Coaxial connector 5a Connector shell 6 Dipole antenna 7 Radome 7a Radome canopy 7b radome bottom cover 7c radome side wall 7d radome canopy central groove 8 copper plate 9 first dipole antenna 10 second dipole antenna 11 third dipole antenna 12 coaxial feed line 12x annular slit 13 metal pipe 14 spacer 15 radome 16 Copper plate

(72) Inventor Masaaki Yamabayashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. In the company

Claims (9)

[Claims] 1. A coaxial feed line, at least one dipole antenna fed by the coaxial feed line, at least one parasitic element arranged in the vicinity of the dipole antenna, the dipole antenna and the parasitic element. A mobile radio antenna, comprising: a covered cylindrical radome, wherein the parasitic element is supported by the radome. 2. A dipole antenna, wherein an antenna element in which an inner conductor of a coaxial feed line is extended upward by about 1/4 wavelength from an upper end of an outer conductor, and one end is connected to an upper end of the outer conductor to connect the outer side of the coaxial feed line. 2. The mobile radio antenna according to claim 1, wherein the mobile radio antenna is composed of a quarter-wave sleeve-shaped metal pipe covered with the cover. 3. The mobile radio antenna according to claim 1, wherein the parasitic element is a metal body fixed to the wall surface of the radome. 4. The mobile radio antenna according to claim 1, wherein the parasitic element is a metal body integrally formed with the radome. 5. The mobile radio antenna according to claim 1, wherein the parasitic element is a metal body formed by printing on the wall surface of the radome. 6. The mobile radio antenna according to claim 1, wherein the parasitic element is a metal body formed by plating on the wall surface of the radome. 7. The mobile radio device according to claim 1, wherein the parasitic element is constituted by fixing a resin film having a metal body formed by printing to an inner wall surface of the radome. antenna. 8. The mobile radio device according to claim 1, wherein the parasitic element is constituted by fixing a resin film having a metal body formed by plating to an inner wall surface of the radome. antenna. 9. The mobile radio antenna according to claim 1, wherein a groove portion is provided inside the canopy of the radome, and a tip portion of the dipole antenna is inserted into the groove portion.