JP2001053530A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the antenna device of a plural frequency operation system, capable of keeping a tilt angle fixed with simple constitution. SOLUTION: A circular ground plate 103 and a ring-like ground plate 104 are connected via plural lumped constant circuits 102. On the circular ground plate 103, a monopole antenna 101a as an antenna element and a wave guide 101b are provided so as to be almost vertical to a main surface. The lumped constant circuits 102 perform electrical coupling or interruption between the circular ground plate 103 and the ring-like ground plate 104 corresponding to an excitation frequency to the monopole antenna 101a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication device used for mobile communication, and more particularly to an antenna device mounted on a communication device used for mobile communication.

[0002]

2. Description of the Related Art A conventional antenna device will be described with reference to FIG. FIG. 7 is a schematic diagram illustrating an example of a configuration of a conventional antenna device. As shown in FIG. 7, a conventional antenna device has a monopole antenna 702 and a director 70 on a finite ground plane 701 as antenna elements.
3 is provided. Monopole antenna 70
2 are excited by two different frequencies.

[0003]

However, the above-mentioned conventional antenna device has the following problems. That is, the direction of the maximum radiated power of the monopole antenna 702 installed on the finite ground plane 701 is inclined above the ground plane, and the angle of inclination (tilt angle) changes according to the size of the ground plane 701. . That is, when the monopole antenna 702 is excited at different frequencies on the same ground plane 701, the tilt angle changes according to each frequency. For this reason, in the antenna apparatus of the above-described system that is excited by a plurality of frequencies (hereinafter, referred to as a “multi-frequency operation system”), the tilt angle cannot be fixed, so that the reception characteristics deteriorate (the reception characteristics deteriorate). The directivity changes with frequency).

[0004] As a method of solving the above problems,
Japanese Patent Application Laid-Open No. Hei 10-93321 discloses a technique in which a plurality of antenna elements are provided to switch the direction of a main beam. However, this method has a problem that the configuration of the entire apparatus becomes very complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an antenna device of a multi-frequency operation system capable of maintaining a constant tilt angle with a simple configuration.

[0006]

An antenna device according to the present invention comprises at least two grounding conductors formed of a plate-like body and connected through a conducting means, and an antenna which is substantially perpendicular to a main surface of the grounding conductor. At least one antenna element provided on any of the ground conductors so that
The conductive means changes an area of a ground conductor having the same potential as a ground conductor provided with the antenna element according to a change in an excitation frequency for the antenna element.

According to the present invention, the area of the ground conductor having the same potential as the ground conductor provided with the antenna element can be changed in accordance with the variation of the excitation frequency for the antenna element. Even when the excitation frequency is changed, the tilt angle of the antenna element can always be kept constant. Therefore, it is possible to provide an antenna device of a multi-frequency operation system capable of maintaining a constant tilt angle with a simple configuration.

The antenna device according to the present invention is characterized in that the conducting means changes the area so that the tilt angle of the antenna element is substantially constant.

According to the present invention, when the excitation frequency for the antenna element changes, according to each excitation frequency,
Since the area of the ground conductor having the same potential as the ground conductor provided with the antenna element is changed so that the tilt angle of the antenna element always becomes a constant value, the tilt angle is kept constant with a simple configuration. It is possible to provide an antenna device of a multi-frequency operation system capable of performing the above.

[0010] In the antenna device of the present invention, when the excitation frequency is a predetermined frequency, the conductive means electrically connects the connected ground conductors, and the excitation frequency is not the predetermined frequency. In this case, the connection between the connected ground conductors is electrically cut off.

According to the present invention, the conduction means performs electrical connection or disconnection between the connected ground conductors,
In accordance with the excitation frequency for the antenna element, it is possible to reliably change the area of the ground conductor having the same potential as the ground conductor provided with the antenna element.

The antenna device according to the present invention is characterized in that the conducting means is constituted by a lumped constant circuit or a distributed constant circuit.

According to the present invention, since the conducting means is constituted by a distributed constant circuit or a lumped constant circuit, electrical connection and disconnection between the connected ground conductors can be reliably performed.

A communication terminal device according to the present invention includes any one of the above antenna devices. A base station apparatus according to the present invention includes any one of the above antenna apparatuses.

According to the present invention, good wireless communication can be performed by using a multi-frequency operation type antenna device capable of maintaining a constant tilt angle with a simple configuration.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is that the area of the ground conductor having the same potential as the ground conductor provided with the monopole antenna is changed according to the change of the excitation frequency for the monopole antenna. It is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic diagram showing a configuration of an antenna device according to Embodiment 1 of the present invention.
Note that, in the present embodiment, the following description will be given taking a case where a two-frequency two-element antenna system is adopted as an example. As shown in FIG. 1, an antenna device 100 according to the present embodiment includes a monopole antenna 101a and a director (reflector) 101b as antenna elements, a lumped constant circuit (distributed constant circuit) 102, and a circular ground plane 103.
And a ring-shaped base plate 104.

In FIG. 1, a circular ground plane (ground conductor) 10
3 and the ring-shaped ground plane 104 are provided via a plurality of lumped constant circuits (distributed constant circuits) 102. The circular ground plate 103 and the ring-shaped ground plate 104 are both formed of plate-like bodies.

The lumped constant circuit (distributed constant circuit) 102
This is a circuit for electrically connecting or disconnecting the circular ground plate 103 and the ring-shaped ground plate 104. Here, an example in which four lumped constant circuits (distributed constant circuits) 102 are provided is shown. However, the lumped constant circuit (distributed constant circuit) 102 reliably performs the electrical connection and cutoff between the above-mentioned various boards. The number of the lumped constant circuits (distributed constant circuits) 102 is not limited as long as it can be performed. A specific internal configuration of the lumped constant circuit (distributed constant circuit) 102 will be described later.

On the circular ground plate 103, a monopole antenna 101a and a director 101b are provided so as to be substantially perpendicular to the main surface. In the present embodiment,
Since the two-frequency two-antenna element system is adopted, the monopole antenna 101a is fed with power so that two different frequencies (the first frequency f1 or the second frequency f1) are different from each other.
It is excited by the frequency f2).

Further, the size of the circular ground plate 103 and the ring-shaped ground plate 104 is adjusted so that the tilt angle becomes substantially the same in each case where the monopole antenna 101a is excited by the first frequency and the second frequency. Are set in accordance with various conditions such as the size of the image.

Here, a lumped constant circuit (distributed constant circuit) 1
02 will be specifically described. The lumped constant circuit (distributed constant circuit) 102 may have any configuration as long as it can perform the electrical connection and cutoff between the above-mentioned boards, but here, as an example, is configured by an RLC series circuit. The following describes the case where

The impedance Z of the lumped constant circuit (distributed constant circuit) 102 is expressed by the following equation. Z = R + j (ωL−1 / ωC) −

Here, the circular ground plate 103 and the ring-shaped ground plate 1
In order to electrically couple the light-emitting element 04 with the same, as is clear from the above equation, the following equation may be satisfied. R = 0−j (ωL−1 / ωC) = 0−

Further, in order to satisfy the above expression, the following expression may be satisfied. .omega.L-1 / .omega.C = 0-Here, since .omega. = 2.pi.f, the excitation frequency f is expressed by the following equation. f = 1 / (2π (LC) ^1/2 ) −

Therefore, the circular ground plate 10 at a certain excitation frequency f
A lumped constant circuit (distributed constant circuit) is configured by using L and C calculated from the above equation in order to electrically couple the ring 3 and the ring-shaped ground plane 104. Specifically, as will be described later, the circular ground plate 103 and the ring-shaped ground plate 104 are electrically coupled at the time of excitation by the second frequency f2, so that by substituting f2 into the above equation, L and C can be obtained.
Is calculated.

Next, the operation of the antenna device having the above configuration will be described. First, when the monopole antenna 101a is excited by the first frequency f1, the circular ground plate 1
03 and the ring-shaped ground plane 104 are electrically disconnected by the lumped constant circuit (distributed constant circuit) 102. This allows
The monopole antenna 101a has a circular ground plate 1 as a whole.
03 is provided. The tilt angle of the monopole antenna 101a at this time is defined as θ1.

Next, the monopole antenna 101a is
When excited by the frequency f2, the circular ground plane 103
And the ring-shaped ground plane 104 are electrically coupled by a lumped constant circuit (distributed constant circuit) 102. As a result, the monopole antenna 101a as a whole is
3 and the ring-shaped ground plate 104 are provided on the ground plate having the size obtained by adding them. That is, the monopole antenna 10
The current flowing through the circular ground plane 103 by supplying power to 1 a also flows through the lumped ground plane 104 via the lumped constant circuit (distributed constant circuit) 102. Thus, the ring-shaped ground plate 104 has substantially the same potential as the circular ground plate 103. The tilt angle of the antenna element 101 at this time is defined as θ2.

Here, considering that the tilt angle of the antenna element 101 changes according to the size of the ground plate on which the antenna element is provided, the tilt angle θ1 at the time of excitation by the first frequency f1 and the second frequency f2 The size of each of the circular ground plate 103 and the ring-shaped ground plate 104 is determined so that the tilt angle θ2 at the time of excitation by the above is substantially the same.
Therefore, in each case where the antenna element 101 is excited by the first frequency f1 and the second frequency f2, the tilt angle of the antenna element 101 is kept substantially the same.

As described above, according to the present embodiment, in each case of exciting the monopole antenna with two different frequencies, the lumped constant circuit (distributed constant circuit)
Since the size of the ground plate on which the antenna element is provided is appropriately changed by using the electrical coupling / cutoff operation by
The tilt angle of the antenna element can always be kept constant. As a result, even when the multi-frequency operation method is adopted, deterioration of the reception characteristics can be suppressed with a simple configuration.

(Embodiment 2) Embodiment 2 is an embodiment in which the number of antenna elements is increased in Embodiment 1. Hereinafter, the antenna device according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram showing a configuration of the antenna device according to Embodiment 2 of the present invention.
In addition, about the structure similar to Embodiment 1 (FIG. 1) in FIG. 2, the same code | symbol as FIG. 1 is attached and detailed description is abbreviate | omitted. Further, in the present embodiment, the following description will be made by taking as an example a case where a two-frequency five-antenna element system is adopted as a two-frequency n-element antenna system.

As shown in FIG. 2, in an antenna device 200 according to the present embodiment, a monopole antenna 101a and four directors 101b are used as antenna elements.
Are provided so as to be substantially perpendicular to the main surface of the circular ground plate 103. When the monopole antenna 101a is excited by the first frequency f1 and the second frequency f2, the operation of the lumped constant circuit (distributed constant circuit) 102 is as follows.
This is the same as that according to the first embodiment. Thereby, in each case where the monopole antenna 101a is excited by the first frequency f1 and the second frequency f2, the tilt angle of the monopole antenna 101a is kept substantially the same.

In this embodiment, the case where five antenna elements are provided on the circular ground plane 103 has been described. However, the present invention is not limited to this, and the number of antenna elements provided on the circular ground plane 103 is appropriately determined. The present invention can be applied to a case where the frequency is changed, that is, a case where a two-frequency n-element antenna system is adopted.

As described above, according to the present embodiment, when a monopole antenna and n directors are used as the antenna elements, in each case where the monopole antenna is excited by two different frequencies. Also, since the size of the ground plane on which the monopole antenna is provided is appropriately changed by using the electrical coupling and blocking operations by the lumped constant circuit (distributed constant circuit), the tilt angle of the monopole antenna can be kept constant. it can.

(Embodiment 3) Embodiment 3 is an embodiment in which three frequencies are used to excite the antenna element in Embodiment 1. Hereinafter, the antenna device according to the present embodiment will be described with reference to FIG. FIG.
FIG. 7 is a schematic diagram showing a configuration of an antenna device according to Embodiment 3 of the present invention. The first embodiment shown in FIG.
The same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and detailed description is omitted. In the present embodiment, a case where a three-frequency two-element antenna system is adopted will be described as an example. In this method, the monopole antenna 101a is excited by three different frequencies (first frequency f1 to third frequency f3).

As shown in FIG. 3, in the antenna device 300 according to the present embodiment, the ring-shaped ground plate 104
It is provided on the circular ground plane 103 via lumped constant circuits (distributed constant circuits) 102a to 102d.
01 is a lumped constant circuit (distributed constant circuit) 302a-30
It is provided on the ring-shaped main plate 104 via 2d.

The ring-shaped base plate 301 is formed of a plate like the ring-shaped base plate 104 in the first embodiment. Further, the size of the ring-shaped ground plate 301 is such that the monopole antenna 101a has the first frequency f1.
The tilt angle is set in accordance with various conditions such as the magnitude of each frequency so that the tilt angle becomes substantially the same in each case excited by the third frequency f3.

Lumped constant circuit (distributed constant circuit) 102a-
102d and lumped constant circuit (distributed constant circuit) 302a
The basic configuration of to 302d is the same as the lumped constant circuit (distributed constant circuit) 102 in the first embodiment described above. Hereinafter, each of the above lumped constant circuits (distributed constant circuits)
A difference from the first embodiment will be described.

Lumped constant circuit (distributed constant circuit) 102a-
At least one of 102d (102a as an example)
Electrically connects the circular ground plate 103 and the ring-shaped ground plate 104 at the time of excitation by the second frequency f2. Therefore, L and C in the inside thereof are calculated by substituting f2 into the above equation. .

A lumped constant circuit (distributed constant circuit) 10
2a to 102d (for example, 10a
2b) and a lumped constant circuit (distributed constant circuit) 302
a to 302d (for example, 302a to 302d)
a) electrically connects the circular ground plate 103 and the ring-shaped ground plate 104, and the ring-shaped ground plate 104 and the ring-shaped ground plate 301, respectively, at the time of excitation by the third frequency f3. F3
Is calculated by substituting.

Next, the operation of the antenna device having the above configuration will be described. First, when the monopole antenna 101a is excited by the first frequency f1, the circular ground plate 1
03 and the ring-shaped ground plane 104 are electrically interrupted by lumped constant circuits (distributed constant circuits) 102a to 102d.
As a result, the monopole antenna 101a is provided on the circular ground plate 103 as a whole. The tilt angle of the antenna element 101 at this time is defined as θ1.

Next, the monopole antenna 101a is
When excited by the frequency f2, the circular ground plane 103
The ring-shaped base plate 104 is electrically connected to the ring-shaped base plate 104 by a lumped constant circuit (distributed constant circuit) 102a.
04 and the ring-shaped ground plate 301 are electrically disconnected by lumped constant circuits (distributed constant circuits) 302a to 302d.
As a result, the monopole antenna 101a is in a state of being provided on a ground plate having a size obtained by adding the circular ground plate 103 and the ring-shaped ground plate 104 as a whole. That is, the circular ground plane 103 is supplied by feeding power to the monopole antenna 101a.
Current flows through the lumped constant circuit (distributed constant circuit) 102
The liquid also flows to the ring-shaped ground plate 104 via the line a.
Therefore, the ring-shaped ground plate 104 has substantially the same potential as the circular ground plate 103. The tilt angle of the antenna element 101 at this time is defined as θ2.

Further, when the monopole antenna 101a is excited by the third frequency f3, the circular ground plate 10
3 and ring-shaped base plate 104, and ring-shaped base plate 104
And the ring-shaped ground plate 301 are electrically coupled by a lumped constant circuit (distributed constant circuit) 102b and a lumped constant circuit (distributed constant circuit) 302a, respectively. As a result, the monopole antenna 101a is provided on a ground plate having a size obtained by adding the circular ground plate 103, the ring-shaped ground plate 104, and the ring-shaped ground plate 301 as a whole. That is, a current flowing through the circular ground plane 103 by feeding power to the monopole antenna 101a flows through the lumped ground plane 104 through the lumped constant circuit (distributed constant circuit) 102b, and further flows through the lumped constant circuit (distributed constant circuit) 302a. It flows to the ring-shaped main plate 301. The tilt angle of the antenna element 101 at this time is defined as θ3.

Here, as described above, considering that the tilt angle of the monopole antenna 101a changes according to the size of the ground plane on which the antenna element is provided, the tilt angle of the first frequency f1 to the third frequency f3 is considered. In order that the tilt angles θ1 to θ3 at the time of excitation by each become approximately the same,
The size of each of the circular ground plate 103, the ring-shaped ground plate 104, and the ring-shaped ground plate 301 is determined. Therefore, in each case where the antenna element 101 is excited by each of the first frequency f1 to the third frequency f3, the tilt angle of the monopole antenna 101a is kept substantially the same.

As described above, according to the present embodiment, in each case where a monopole antenna is excited by three different frequencies, a lumped constant circuit (distributed constant circuit)
Since the size of the ground plate on which the monopole antenna is provided is appropriately changed by using the electric coupling / blocking operation of the monopole antenna, the tilt angle of the monopole antenna can always be kept constant. As a result, even when the multi-frequency operation method is adopted, deterioration of the reception characteristics can be suppressed with a simple configuration.

(Embodiment 4) Embodiment 4 is an embodiment in which the number of antenna elements is increased in Embodiment 3. Hereinafter, the antenna device according to the present embodiment will be described with reference to FIG. FIG. 4 is a schematic diagram showing a configuration of an antenna device according to Embodiment 4 of the present invention.
In addition, about the structure similar to Embodiment 3 (FIG. 3) in FIG. 4, the same code | symbol as FIG. 3 is attached | subjected and detailed description is abbreviate | omitted. Further, in the present embodiment, the following description will be made by taking as an example a case where a three-frequency five-antenna element system is adopted as a three-frequency n-element antenna system.

As shown in FIG. 4, in an antenna device 400 according to the present embodiment, a monopole antenna 101a and four directors 101b are used as antenna elements.
Are provided so as to be substantially perpendicular to the main surface of the main plate 103. The configurations and operations of the lumped constant circuits (distributed constant circuits) 102a to 102d and the lumped constant circuits (distributed constant circuits) 302a to 302d in each case where the monopole antenna 101a is excited by the first frequency f1 to the third frequency f3 are as follows. This is the same as that according to the third embodiment described above. Thereby, the monopole antenna 101a
Is excited at the first frequency f1 to the third frequency f3, the tilt angle of the monopole antenna 101a is kept substantially the same.

In this embodiment, the case where five antenna elements are provided on the circular ground plane 103 has been described. However, the present invention is not limited to this.
The present invention can also be applied to a case where the number of antenna elements provided in the antenna is appropriately changed, that is, a case where a three-frequency n-element antenna system is adopted.

As described above, according to the present embodiment, when a monopole antenna and n directors are used as antenna elements, in each case where the monopole antenna is excited by three different frequencies, Also, since the size of the ground plane on which the monopole antenna is provided is appropriately changed by using the electrical coupling and blocking operations by the lumped constant circuit (distributed constant circuit), the tilt angle of the monopole antenna can be kept constant. it can.

(Embodiment 5) Embodiment 5 is an embodiment in which the frequency for exciting the monopole antenna is further increased in Embodiment 3. Hereinafter, the antenna device according to the present embodiment will be described with reference to FIG. FIG. 5 is a schematic diagram illustrating a configuration of an antenna device according to Embodiment 5 of the present invention. In addition, about the structure similar to Embodiment 3 (FIG. 3) in FIG. 5, the same code | symbol as FIG. 3 is attached | subjected and detailed description is abbreviate | omitted. Further, in the present embodiment, a case where an n-frequency two-element antenna system is adopted will be described as an example. In this system, the monopole antenna 101a has n different from each other.
It is excited by different kinds of frequencies (first frequency f1 to n-th frequency fn).

As shown in FIG. 5, in antenna device 500 according to the present embodiment, ring-shaped ground plate 501 is
It is provided on the ring-shaped ground plate 301 via lumped constant circuits (distributed constant circuits) 502a to 502d. Further, another ring-shaped ground plate (not shown) is provided on the ring-shaped ground plate 501 via a lumped constant circuit (distributed constant circuit).
Similarly, a ring-shaped ground plate is provided via a lumped constant circuit (distributed constant circuit) so that the total number of ground plates (a circular ground plate and a ring-shaped ground plate) becomes n.

Each of the ring-shaped base plates is the same as the ring-shaped base plate 104 and the ring-shaped base plate 30 in the above-described embodiment.
As in the case of 1, it is constituted by a plate-like body. The size of the ring-shaped ground plate 301 may be various such as the size of each of the above-mentioned frequencies so that the tilt angle is substantially the same in each case where the monopole antenna 101a is excited by the first frequency f1 to the n-th frequency fn. It is set according to conditions. Further, the size of the ring-shaped ground plate provided outside the ring-shaped ground plate 301 is set similarly.

Lumped constant circuits (distributed constant circuits) 502a-
The basic configuration of 502d is the same as the lumped constant circuit (distributed constant circuit) in the above-described embodiment.
Hereinafter, differences between the lumped constant circuits (distributed constant circuits) and the third embodiment will be described.

Lumped constant circuit (distributed constant circuit) 102a-
102d (for example, 102d
c), lumped constant circuits (distributed constant circuits) 302a to 302
d and at least one of them (for example, 302b) and lumped constant circuits (distributed constant circuits) 501a to 501
At least one of d (for example, 501a) is
At the time of excitation by the fourth frequency f4, the circular ground plate 103, the ring-shaped ground plate 104, and the ring-shaped ground plate 104 are respectively provided.
And the ring-shaped ground plate 301, and the ring-shaped ground plate 301 and the ring-shaped ground plate 501 are electrically coupled, and L and C in the interior thereof are calculated by substituting f4 into the above equation. .

Next, the operation of the antenna device having the above configuration will be described. When the monopole antenna 101a is excited by each of the first frequency f1 to the third frequency f3, the coupling / cutoff operation of each lumped constant circuit (distributed constant circuit) is the same as that according to the third embodiment described above. is there.

When the monopole antenna 101a is excited by the fourth frequency f4, the circular ground plate 103 and the ring-shaped ground plate 104, and the ring-shaped ground plate 104 and the ring-shaped ground plate 3
01, the ring-shaped ground plate 301 and the ring-shaped ground plate 501 are electrically coupled by a lumped constant circuit (distributed constant circuit) 102c, a lumped constant circuit (distributed constant circuit) 302b, and a lumped constant circuit (distributed constant circuit) 502a, respectively. Is done.

Thus, the monopole antenna 101a
Is placed on a ground plate having a size obtained by adding the circular ground plate 103, the ring-shaped ground plate 104, the ring-shaped ground plate 301, and the ring-shaped ground plate 501 as a whole. The tilt angle of the antenna element 101 at this time is defined as θ4. That is, the power supply to the monopole antenna 101a causes
03 is a lumped constant circuit (distributed constant circuit) 1
02c through the lumped constant circuit (distributed constant circuit) 302b.
1 and a lumped constant circuit (distributed constant circuit) 50
It flows to the ring-shaped main plate 501 via 2a.
Therefore, the ring-shaped ground plate 501 has substantially the same potential as the ring-shaped ground plate 104 and the circular ground plate 103.

Similarly, when the monopole antenna 101a is excited by the fifth frequency f5, at the time of excitation by the fourth frequency, the ground plate further provided outside the ring-shaped ground plate 501 is connected to the ring-shaped ground plate 501. Electrically coupled. Assume that the tilt angle of the monopole antenna 101a is θ5.

The monopole antenna 101a has an n-th
When excited by the frequency, the ring-shaped ground plate provided further outside is sequentially electrically coupled to the inner ring-shaped ground plate. The tilt angle of the monopole antenna 101a at the time of excitation by the n-th frequency is defined as θn.

Here, as described above, considering that the tilt angle of the monopole antenna 101a changes according to the size of the ground plane on which the monopole antenna is provided, the first frequency f1 to the n-th frequency fn are considered. Of the circular ground plate 103, the ring-shaped ground plate 104, the ring-shaped ground plate 301, the ring-shaped ground plate 501, and the ring-shaped ground plate sequentially provided on the outside so that the tilt angles θ1 to θn at the time of excitation by each of the above are substantially the same. Each size is determined. Therefore, in each case where the monopole antenna 101a is excited by each of the first frequency f1 to the n-th frequency fn, the tilt angle of the monopole antenna 101a is kept substantially the same.

As described above, according to the present embodiment, in each case where the monopole antenna is excited by a plurality of different frequencies, the lumped constant circuit (distributed constant circuit) is used to perform the electric coupling / cutoff operation. Since the size of the ground plane on which the monopole antenna is provided is appropriately changed, the tilt angle of the monopole antenna can always be kept constant. As a result, even when the multi-frequency operation method is adopted, deterioration of the reception characteristics can be suppressed with a simple configuration.

(Embodiment 6) Embodiment 6 is an embodiment in which the number of antenna elements is increased in Embodiment 5. Hereinafter, the antenna device according to the present embodiment will be described with reference to FIG. FIG. 6 is a schematic diagram showing a configuration of an antenna device according to Embodiment 6 of the present invention.
In addition, about the structure similar to Embodiment 5 (FIG. 5) in FIG. 6, the same code | symbol as FIG. 5 is attached | subjected, and detailed description is abbreviate | omitted.

As shown in FIG. 6, in an antenna device 600 according to the present embodiment, a monopole antenna 101a and four directors 101b are used as antenna elements.
Are provided so as to be substantially perpendicular to the main surface of the circular ground plate 103. The monopole antenna 101a has the first frequency f
The operation of each lumped constant circuit (distributed constant circuit) in each case where excitation is performed by the first to n-th frequencies fn is the same as that of the fifth embodiment. As a result, the monopole antenna 101a is switched from the first frequency f1 to the n-th frequency f
In each case excited by n, the tilt angle of the monopole antenna 101a is kept substantially the same.

In the present embodiment, the case where five antenna elements are provided on the circular ground plane 103 has been described. However, the present invention is not limited to this.
The present invention can also be applied to a case where the number of antenna elements provided in the above is changed as appropriate, that is, a case where an n-frequency n-element antenna system is adopted.

In the above embodiment, a case where a circular base plate having a plate shape and a ring-shaped base plate are used as the base plate has been described. However, the present invention is not limited to this.
As long as the tilt angle becomes constant when the frequency at the time of excitation of the monopole antenna is changed, the present invention can be applied to a case where a ground plane of any shape is used.

Further, in the above embodiment, an example has been shown in which the lumped constant circuit (distributed constant circuit) performs the coupling / cutoff operation in accordance with the frequency at the time of excitation of the monopole antenna. Under the condition that the tilt angle of the pole antenna is always substantially the same, the present invention can be applied to a case where the coupling / cutoff operation of the lumped constant circuit (distributed constant circuit) is appropriately changed.

Further, in the above-described embodiment, a case has been described where a lumped constant circuit (distributed constant circuit) is used to electrically couple or cut off each board, but the present invention is not limited to this. However, the present invention can be applied to a case where any circuit that electrically connects or disconnects the above-mentioned various boards is used instead of the lumped constant circuit (distributed constant circuit).

The antenna device of the present invention can be applied to a communication terminal device such as a mobile station device and a base station device in a wireless communication system.

As described above, according to the present invention,
Since the area of the ground conductor that has the same potential as the ground conductor on which the monopole antenna is provided is changed in accordance with the fluctuation of the excitation frequency for the monopole antenna, a plurality of units that can maintain a constant tilt angle with a simple configuration An antenna device using a frequency operation method can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an antenna device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of an antenna device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a configuration of an antenna device according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram showing a configuration of an antenna device according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram showing a configuration of an antenna device according to a fifth embodiment of the present invention.

FIG. 6 is a schematic diagram showing a configuration of an antenna device according to a sixth embodiment of the present invention.

FIG. 7 is a schematic view showing an example of a configuration of a conventional antenna device.

[Explanation of symbols]

101a monopole antenna 101b director 102, 102a to 102d, 302a to 302d, 5
02a to 502d Lumped constant circuit (distributed constant circuit) 103 Circular ground plane 104, 301, 501 Ring-shaped ground plane

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Eno 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa F-term (reference) in Matsushita Communication Industrial Co., Ltd. 5J020 AA03 BA02 BC08 DA03 DA04 DA08 5J046 AA04 AB06 PA02

Claims (6)

[Claims] 1. At least two grounding conductors formed of a plate-like body and connected via conductive means, and provided on one of the grounding conductors so as to be substantially perpendicular to a main surface of the grounding conductor. At least one antenna element,
Wherein the conducting means changes an area of a ground conductor having the same potential as a ground conductor provided with the antenna element according to a change in an excitation frequency of the antenna element. 2. The antenna device according to claim 1, wherein the conduction unit changes the area such that a tilt angle of the antenna element is substantially constant. 3. The conduction means electrically connects the ground conductors connected when the excitation frequency is a predetermined frequency, and when the excitation frequency is not the predetermined frequency, 3. The antenna device according to claim 2, wherein the connected ground conductors are electrically disconnected. 4. The antenna device according to claim 3, wherein said conduction means is constituted by a lumped constant circuit or a distributed constant circuit. 5. A communication terminal device comprising the antenna device according to any one of claims 1 to 4. 6. A base station apparatus for performing wireless communication with the communication terminal apparatus according to claim 5.