JPH1117439A - Antenna for mobile radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a vertical diversity antenna to reduce the number of components, reduce attaching parts as well, simplify constitution and reduce a manufacture cost while having the same functions as the conventional antenna. SOLUTION: This antenna is composed of the vertical diversity antenna provided with a first vertical dipole antenna 10a and a second vertical dipole antenna 20. In this case, the upward opening 15a of the choke 15 of a 1/2 length provided with a connection point on a vertical center in a 1/2 wavelength is provided on a point 1/4 wavelength below the lower end of the first vertical dipole antenna 10a, an outer conductor 18b is connected at the connection point 15d at the middle point 15c of a vertical direction and the upper end of the second vertical dipole antenna 20 is brought to the point 1/4 wavelength below the downward opening 15b of the choke 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio antenna for preventing leakage current to a feed line in a vertical diversity antenna.

[0002]

2. Description of the Related Art In recent years, mobile radios such as cellular phones and personal handyphone systems (PHS) have been actively used. Diversity antennas are often used for antennas used for mobile radio base stations because the location of the other party is not constant and communication conditions change.

Hereinafter, a vertical diversity antenna used in a conventional mobile radio base station will be described. Before that, a conventional vertical dipole antenna used for the vertical diversity antenna will be described with reference to FIG. In FIG. 5, a vertical dipole antenna 10 is a quarter-wave antenna element 1.
The center conductor 18 of the coaxial feed line 18, which is a semi-rigid cable, is provided at each of the feeding points 13 and 14, for example.
a and the outer conductor 18b. In this case, assuming that a current distribution phase distribution is generated in the vertical dipole antenna 10 as indicated by an upward arrow, the outer conductor 18b of the coaxial feed line 18 has a vertical dipole antenna 1
A leakage current having a current phase distribution as shown in FIG. Since the radiation due to the leakage current affects the radiation of the vertical dipole antenna 10 and the directivity in the vertical plane is disturbed, measures such as inserting a choke are taken.

In the case of a vertical diversity antenna, since the vertical dipole antennas are arranged vertically, as shown in the sectional view of the conventional vertical diversity type mobile radio antenna shown in FIG. , The leakage current increases in the outer conductor 18b of the coaxial feed line from the upper direction toward the first vertical dipole antenna, and the radiation by this also affects the radiation of the vertical dipole antenna 10. The measures will be described below.

In FIG. 6, a first vertical dipole antenna 10 includes a quarter-wavelength antenna element 11 and a quarter-wavelength sleeve antenna element 12.
Power is supplied to the power supply points 13 and 14 by the center conductor 18a and the outer conductor 18b of the coaxial power supply line 18, respectively. Then, at a point below the lower end 12a of the first vertical dipole antenna 10 by a quarter wavelength, a quarter of the sleeve shape is formed.
The connection point 16b is connected to the outer conductor 18b of the coaxial feed line 18 so that the opening 16a of the first choke 16 having the wavelength length comes. At a position slightly below the first choke 16, another quarter-wave second choke 17 is provided with an aperture 17.
a with the outer conductor 18 of the coaxial feeder 18 at point 17b.
b. Since the position of the second choke 17 has a relationship with the position of the second antenna 20, the details will be described later.

[0006] The second vertical dipole antenna 20 is a first vertical dipole antenna.
Is located below the vertical dipole antenna 10 and is composed of a quarter-wavelength antenna element 21 and a quarter-wavelength sleeve antenna element 22. The center conductor 28a of the coaxial feeder 28 is provided at feed points 23 and 24, respectively. And the outer conductor 28b. If necessary, similarly to the first vertical dipole antenna 10, the outer conductor 28 b of the feeder line 28 is also provided below the second vertical dipole antenna 20.
A quarter-wave choke may be provided on the top, but this is not directly related to the present description and will be omitted.

The operation of the vertical diversity antenna configured as described above is as follows. When power is supplied to the first vertical dipole antenna 10 via the coaxial feed line 18, the vertical dipole antenna 10 radiates radio waves and leaks current from the lower end 12 a of the sleeve antenna element 12 to the outer conductor 18 b of the coaxial feed line 18. Is excited.
Here, when the choke 16 does not exist, the outer conductor 18b of the coaxial feed line 18 operates as if it were an antenna due to the leakage current, and the first vertical dipole antenna 10
And disturbs its directivity in the vertical plane, that is, the directional beam becomes uneven in the vertical direction, causing a change in tilt angle and generation of side lobes. Also,
Leakage current flows into the transceiver and causes interference. Here, the first vertical dipole antenna 1
If the current phase distribution of 0 is the phase indicated by the upward arrow as shown in the figure, the leakage current distribution of the outer conductor of the coaxial feed line 18 immediately below the current phase distribution is indicated by the upward arrow. Therefore, the first
Of the first vertical dipole antenna 10, a phase opposite to the leakage current, that is, a current phase indicated by a downward arrow, is formed in a portion of the opening of the first choke 16 located at a position one quarter wavelength lower from the lower end of the first vertical dipole antenna 10. The first choke 16 is provided in order to generate a distribution, cancel the leakage current, make the impedance at the point of the opening 16a infinite, and eliminate the leakage current distribution downward from here.

When the second vertical dipole antenna 20 is similarly fed by the coaxial feed line 28, the radiation from this antenna 20 causes the outer conductor of the coaxial feed line 18 for the first vertical dipole antenna. 18b
A leakage current also occurs, and this leakage current flows in both the up and down directions.
In the upward direction, the leakage current is blocked by the second choke 17 and the directivity of the first and second vertical dipole antennas 10 and 20 is prevented. For this reason, the second choke 17 is connected to the outer conductor 18b at a point 17b so as to have a downward opening 17a at a quarter wavelength from the upper end of the second vertical dipole antenna 20.

[0009]

As described above, the leakage current from the first vertical dipole antenna 10 is blocked by the first choke 16 and the leakage current from the second vertical dipole antenna 20 is directed upward. The leakage current of the first and second vertical dipole antennas 10 and 20 can be prevented from adversely affecting the directivity of the first and second vertical dipole antennas 10 and 20 by preventing upward leakage with the second choke 17. The second chokes 16, 17 must be provided separately,
There has been a problem that the number of parts increases, the number of installation steps increases, and the manufacturing cost increases.

An object of the present invention is to solve the above problems,
To provide a mobile radio antenna having a vertical diversity antenna, which has the same function but has a small number of parts and a small number of mounting points, has a simple configuration, and can be manufactured at low cost. is there.

[0011]

According to the present invention, there is provided a mobile radio antenna according to the present invention, comprising: a first vertical dipole antenna fed by a coaxial feed line; A mobile antenna comprising a vertical diversity antenna having a vertical dipole antenna having an opening upward at a point one quarter wavelength lower than a lower end of the first vertical dipole antenna; Has a downward opening at a point one-quarter wavelength above the upper end of the vertical dipole antenna, and is connected to the outer conductor of a coaxial feeder for feeding the first vertical dipole antenna at the center in the vertical direction. A choke having a half wavelength is provided. With the configuration described above, the leakage current from the first vertical dipole antenna to the coaxial feed line and the leakage current from the second vertical dipole antenna to the coaxial feed line in the upward direction can be controlled by one choke. Leakage current can be prevented.

According to a second aspect of the present invention, there is provided the mobile radio antenna according to the first aspect, wherein the first vertical dipole antenna is provided between the lower end of the first vertical dipole antenna and the choke and / or the second radio antenna. A coaxial feed line is inserted between the upper end of the second vertical dipole antenna and the choke in units of a half wavelength. With the configuration described above, the distance between the first and second vertical dipole antennas can be changed.

The mobile radio antenna according to a third aspect of the present invention is the mobile radio antenna according to the first or second aspect, wherein the choke is made of a conductive material and has a cylindrical shape and the same length. The upper and lower pieces are made of a conductive material, and extend vertically around a disc portion having an opening at the center thereof, through which the coaxial feeder line passes. A middle piece having a holding portion fitted around or around the circumference, electrically connected to the opening of the middle piece through the coaxial power supply line, and an upper piece and a lower piece respectively above and below the middle piece. A piece is inserted into the holding portion, and the length of the choke in the vertical direction is a half wavelength. With the above configuration, attachment to the coaxial feeder is facilitated.

As a result of using the present invention, the influence of the leakage current to the coaxial feed line on the radiation from the vertical dipole antenna is reduced, the directional beam in the vertical plane becomes uniform in the vertical direction, and the tilt angle is reduced. It is possible to provide a mobile radio antenna having a vertical diversity antenna configuration that does not change and hardly generates side lobes.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of a mobile radio antenna which is a vertical diversity antenna according to an embodiment of the present invention. 1, the same components as those in FIGS. 5 and 6 are denoted by the same reference numerals. In FIG. 1, the mobile radio antenna of the present embodiment includes a first vertical dipole antenna 10a and a second vertical dipole antenna 20, and differs from the conventional example of FIG. 6 in the following points. (A) The first vertical dipole antenna 10a is a quarter-wave antenna element 11 having a cylindrical shape (sleeve shape) as an upper radiation element as compared with the antenna 10 of FIG.
a, and a disc-shaped connecting member 11 is provided at the bottom of the cylinder.
While ab is connected to the cylindrical antenna element 11a, it is connected to the center conductor 18a of the coaxial feed line 18. By providing the quarter-wave antenna element 11a having a cylindrical shape in this way, it can be formed symmetrically with the quarter-wave antenna element 12 having a lower sleeve shape. As compared with the case where the bar-shaped quarter-wave antenna element 11 is provided as described above, a more uniform and improved directional characteristic in the vertical plane can be obtained. (B) Leakage current downward from the first vertical dipole antenna 10a and the second vertical dipole antenna 20
A half-wavelength choke 15 that commonly copes with an upward leakage current from the first vertical dipole antenna 10a has an opening 1
The outer conductor 18b of the coaxial feed line 18 is connected to the middle point 15c at a connection point 15d such that the 5a comes. Then, from the downward opening 15b of the choke 15, a quarter
It is configured such that the upper end of the second vertical dipole antenna 20 comes to a point 15e lower by the wavelength.

The operation of the mobile radio antenna according to the present embodiment configured as described above will be described with reference to FIG. If the first vertical dipole antenna 10a is fed by the coaxial feed line 18 and the vertical dipole antenna 10a radiates radio waves according to the current phase distribution indicated by the upward arrow, the coaxial feed line 18 extends from the lower end 12a of the sleeve antenna element 12. In FIG. 1, a leakage current having a current phase distribution indicated by an upward arrow is excited downward in the outer conductor 18b. In order to prevent this leakage current, the upper half of the choke 15 creates a current phase distribution shown by the downward arrow in FIG. 1 to cancel the leakage current, thereby making the impedance at the point of the opening 15a infinite and blocking the leakage current. I do.

Similarly, the second vertical dipole antenna 2
Assuming that the vertical dipole antenna 20 radiates radio waves according to the current phase distribution indicated by the upward arrow when 0 is supplied by the coaxial feed line 28, the vertical dipole antenna 20 is directed upward from the upper end of the antenna element 21 to the outer conductor 18b of the coaxial feed line 18. In FIG. 1, a leakage current having a current phase distribution indicated by an upward arrow is excited. In order to prevent this leakage current, the lower half of the choke 15 creates the current phase distribution shown by the downward arrow in FIG. 1 to cancel the leakage current, thereby making the impedance at the point of the opening 15b infinite and blocking the leakage current. .

In the present embodiment, the distance between the lower end of the first vertical dipole antenna 10a and the upper end of the second vertical dipole antenna 20 is one wavelength, but the distance between the upper and lower antennas must be increased. When is the first
Between the vertical dipole antenna 10a and the choke 15 and / or between the choke 15 and the second vertical dipole antenna 20 in a unit of a half wavelength, that is, a natural number of a half wavelength What is necessary is just to insert a coaxial feeder line having twice the length.

FIG. 2 is a sectional view showing a detailed configuration of the choke of the mobile radio antenna of FIG. 1, and FIG. 3 is an exploded perspective view showing a detailed configuration of the choke of FIG. 2 and 3, the choke 15 is made of a conductive material,
It is composed of a middle piece 15f, an upper piece 15j and a lower piece 15k. The middle piece 15f is a short cylindrical holding part 15g.
A disk portion 15h is integrally formed like a bamboo node inside the upper and lower central portions of the disk.
Has an opening 15i through which a hole is formed. The upper piece 15j and the lower piece 15k are formed to have the same shape, and are formed so that their outer diameters are firmly fitted to the inner diameter of the holding portion 15g of the middle piece 15f. And three pieces 15j, 15
f, 15k through the coaxial feed line 18, and the outer conductor 18
b, after electrically connecting around the hole 15i of the middle piece 15f, the upper piece 15j and the lower piece 15k are inserted and fitted into the inner surface of the holding portion 15g of the middle piece 15f and assembled in this state. 3 so that the length in the direction (longitudinal direction) is half the wavelength.
The lengths of the individual pieces 15j, 15f, and 15k are determined in advance.

As a modified example, although not shown, for example, a structure in which the upper piece 15j and the lower piece 15k are inserted into the outer surface of the holding portion 15g of the middle piece 15f may be used. Further, the cylindrical portion of the cylindrical shape of the holding portion 15g does not need to be formed over the entire circumference, and the inner piece 15f shown in FIG.
a, the holding portion 15 is partially formed on the outer periphery of the disk portion 15h.
The upper piece 1 has an inner diameter or an outer diameter of the holding portion 15l.
5j and the lower piece 15k may be formed so as to be fitted.

As described above, according to the present embodiment, in the mobile radio antenna which is a vertical diversity antenna, the upper first vertical dipole antenna 1
The connection point of the coaxial feed line 18 to the outer conductor 18b is located at the center of the upper and lower sides at the point of the half wavelength from the lower end of the second vertical dipole antenna 20 at the point of the half wavelength from the lower end of the second vertical dipole antenna 20. With the provision of the half-wave choke, the leakage current from the first vertical dipole antenna 10a to the outer conductor 18a of the coaxial feed line 18 and the second
Can be prevented by the single choke 15 from the vertical dipole antenna, the material can be reduced, and the mounting can be easily performed. Therefore, the structure is simpler and the manufacturing cost is lower than in the conventional example.

As a result, the radiation from the first and second vertical dipole antennas 10a and 20 is hardly affected, the directional beam in the vertical plane is uniform in the vertical direction, the tilt angle does not change, A vertical diversity antenna with almost no lobe can be configured.

The two vertical dipole antennas 10a,
When it is desired to change the distance between the two, the distance between the lower end of the first vertical dipole antenna 10a and the choke 15 or the upper end of the second vertical dipole antenna 20 and the choke 15
The distance between the first vertical dipole antenna 10a and the second vertical dipole antenna 20 can be extended by adding a coaxial feed line in a unit of a half wavelength between the two.

In the above embodiment, the first vertical dipole antenna 10a is provided with the cylindrical quarter-wave antenna element 11a as the upper radiating element. However, the present invention is not limited to this. 6 conventional antennas 1
0 may be configured. Further, the antenna element 21 may have a sleeve shape.
1a, 21 are the central conductors 18 of the coaxial feed lines 18, 28.
a, 28a may be extended as it is.

[0026]

As described above, according to the mobile radio antenna according to the first aspect of the present invention, the first vertical dipole antenna and the second vertical dipole antenna fed by the coaxial feed line are provided. A mobile diversity antenna comprising a vertical diversity antenna having
Has an upward opening at a point one quarter wavelength below the lower end of the vertical dipole antenna, and has an downward opening at a point one quarter wavelength above the upper end of the second vertical dipole antenna. , The first in the vertical center
And a half-wavelength choke connected to the outer conductor of the coaxial feeder that feeds the vertical dipole antenna.
Therefore, the leakage current to the coaxial feed line from the first vertical dipole antenna and the upward leakage current to the coaxial feed line from the second vertical dipole antenna can be prevented by one choke. . In addition, the number of parts is small, the number of attachment points can be reduced, the configuration is simple, and the manufacturing cost can be reduced.

According to a second aspect of the present invention, in the mobile radio antenna according to the first aspect, between the lower end of the first vertical dipole antenna and the choke, and / or A coaxial feed line is inserted between the upper end of the second vertical dipole antenna and the choke in units of a half wavelength. Therefore, the distance between the first and second vertical dipole antennas can be changed.

Further, according to the mobile radio antenna according to the third aspect, in the mobile radio antenna according to the first or second aspect, the choke is made of a conductive material and has the same length in a cylindrical shape. The upper piece and the lower piece are made of a conductive material, and extend vertically in the center of a disk having an opening through which the coaxial feed line passes. A middle piece having a holding portion to be fitted on the inner circumference or the outer circumference thereof, and electrically connected to the opening of the middle piece through the coaxial feeder line, and a piece above and below the middle piece, respectively. The lower piece is inserted into the holder, and the length of the choke in the vertical direction is a half wavelength. Therefore,
The choke can be easily attached to the coaxial feeder.

As a result of using the present invention, the influence of the leakage current to the coaxial feed line on the radiation from the vertical dipole antenna is reduced, the directional beam in the vertical plane becomes uniform in the vertical direction, and the tilt angle is reduced. It is possible to provide a mobile radio antenna having a vertical diversity antenna configuration that does not change and hardly generates side lobes.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a mobile radio antenna which is a vertical diversity antenna according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a detailed configuration of a choke of the mobile radio antenna of FIG.

FIG. 3 is an exploded perspective view showing a detailed configuration of the choke shown in FIG. 2;

FIG. 4 is a perspective view showing a modification of the middle piece of FIG. 3;

FIG. 5 is a cross-sectional view illustrating a configuration of a conventional vertical dipole antenna.

FIG. 6 is a cross-sectional view illustrating a configuration of a conventional mobile radio antenna of a vertical diversity type.

[Explanation of symbols]

 10, 10a: first vertical dipole antenna; 11, 21, ... quarter-wave antenna element; 12, 22, ... quarter-wave sleeve antenna element; 12a: lower end of dipole 10, 13, 14, 23, 24 ... feeding point, 15 ... choke, 15a, 15b ... opening, 15c ... middle point, 15d ... connection point, 15f, 15fa ... middle piece, 15g, 15l ... holding part, 15h ... disk part, 15i ... opening, 15j ... Upper piece, 15k ... Lower piece, 18, 28 ... Coaxial feed line, 18a, 28a ... Center conductor, 18b, 28b ... Outer conductor, 20 ... Second vertical dipole antenna.

Claims (3)

[Claims] 1. A mobile radio antenna comprising a vertical diversity antenna having a first vertical dipole antenna fed by a coaxial feeder and a second vertical dipole antenna, wherein: Quarter from bottom
The second vertical dipole antenna has an opening upward at a point below the upper end of the second vertical dipole antenna by a quarter wavelength from the upper end of the second vertical dipole antenna. A mobile radio antenna comprising a half-wavelength choke connected to an outer conductor of a coaxial feeder for feeding a vertical dipole antenna. 2. The method according to claim 1, further comprising: a step between the lower end of the first vertical dipole antenna and the choke and / or a step between the upper end of the second vertical dipole antenna and the choke.
2. The mobile radio antenna according to claim 1, wherein a coaxial feed line is inserted in a unit of a half wavelength. 3. The choke is made of a conductive material, and has upper and lower cylindrical pieces having the same length, and is made of a conductive material. A middle piece extending vertically around a disk portion having a hole and having a holding portion for fitting the upper piece and the lower piece at the inner or outer periphery thereof; And the upper piece and the lower piece are inserted into the holding part from above and below the middle piece, respectively, and the length of the choke in the vertical direction is reduced by half. 3. The mobile wireless antenna according to claim 1, wherein the antenna has a wavelength.