JP3255144B2 - Antenna device and communication device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device and a communication device using the same, and more particularly to an antenna device used for a mobile communication device and the like and a communication device using the same.

[0002]

2. Description of the Related Art In recent years, as mobile telephones such as PHS and the like have higher performance, mobile phones have been required to have higher performance such as miniaturization and higher gain. It is becoming.

FIG. 6 shows a conventional antenna device mounted on a mobile communication device. In FIG. 6, the antenna device 1
The ground electrode 3 is formed on one main surface 2a of the mounting substrate 2, and the deleted portion 3 of the ground electrode 3 is formed on the corner of the one main surface 2a.
a, a power supply wiring 4 is formed thereon, and a surface mount antenna 5 is mounted. The power supply wiring 4 is connected to a power supply terminal (not shown) of the surface mount antenna 5 and is connected to a signal source 6 provided on the mounting board 2.

FIG. 7 shows the details of the surface mount antenna 5. The surface mount antenna 5 is disclosed in
No. 3139 discloses the basic configuration.

[0005] In FIG. 7, the surface mount type antenna 5 comprises:
Several electrodes are formed on the surface of a rectangular parallelepiped base 10 made of a dielectric such as ceramics or resin, which is one of the insulators. First, the other main surface 10 of the base 10
A strip-shaped radiation electrode 11 is formed from b to the other main surface 10b again through one end face 10d.
One end of the radiation electrode 11 forms an open end 11a, and the other end is connected to a first ground terminal 12 formed from the end face 10c of the base 10 to one main face 10a. Also,
A power supply electrode 13 is formed on the other main surface 10b of the base 10 so as to be separated from the radiation electrode 11, and one end of the power supply electrode 13 is connected to a power supply terminal 14 formed from the end face 10c of the base 10 to the one main surface 10a. Have been. Similarly, the base 10
A ground electrode 15 is formed on the other main surface 10b of the radiating electrode 11 near the open end 11a.
One end of 5 is connected to a second ground terminal 16 formed from the end face 10c of the base 10 to one main face 10a. The radiation electrode 1 is provided on one main surface 10a of the base 10.
1, fixing terminals 17 and 18 are formed.

Here, the first and second ground terminals 1
2 and 16, power supply terminal 14, fixing terminals 17 and 1
The five electrodes 8 are electrodes that are connected to the ground electrode, the feeder line, and the fixing electrode on the mounting substrate side by soldering when the surface-mount antenna 5 is mounted on the mounting substrate (not shown). Therefore, it is expressed as a terminal to distinguish it from other electrodes.

In the surface-mounted antenna 5 configured as described above, when a high-frequency signal is input to the power supply terminal 14, the capacitance formed between the power supply electrode 13 and the open end 11 a of the radiation electrode 11 is reduced. A high-frequency signal is transmitted to the radiation electrode 11 via the radiating electrode. The radiation electrode 11 has an inductance component of the radiation electrode 11 itself and an open end 11 a of the radiation electrode 11.
And a capacitance formed between the ground electrode 15 and the ground electrode 15, and a part of the energy of the resonance is radiated to the space as a radio wave to function as an antenna.

At this time, one end of the radiation electrode 11 has an open end 11.
a, and since the other end is a ground end, resonance occurs at about 1/4 wavelength, and the direction of the current flowing through the radiating electrode 11, that is, the current 19 flowing through the surface-mounted antenna 5 is determined by the ground end ( Specifically, the first ground terminal 12)
From the direction toward the open end 11a. As a result, the radio wave radiated from the surface mount antenna 5 and the radio wave received by the surface mount antenna 5 are radio waves whose electric field components vibrate mainly in the z-axis direction at the coordinates shown in FIG.

Incidentally, in the surface mount type antenna 5,
Although the electrode and the terminal are formed separately, they can not always be clearly separated at some boundary, and the electrode and the terminal may be integrally formed.

[0010]

The antenna device 1 shown in FIG.
, When a current 19 flows through the surface mount antenna 5, the phase of the current 19 is
An image current 7 different by 80 degrees flows.

When the antenna device 1 is used, the mounting board 2 is covered with a casing made of plastic or metal. The housing is often placed on a desk or in a bag. Often placed on a desk or in a bag adjacent to a conductive object such as a metal, they can be regarded as almost ground conductors. Therefore, depending on the external environment in which such an antenna device 1 is used, the image current 7 of the current 19 flowing through the surface-mount antenna 5
However, there is a problem that the location and direction of the flow vary depending on the adjacent ground conductor, and the characteristics such as the gain and the directivity of the antenna device 1 vary accordingly.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna device whose gain is improved, the characteristic of the antenna device hardly changes depending on an external environment to be used, and a communication device using the same.

[0013]

In order to solve the above problems, an antenna device according to the present invention comprises a strip-shaped radiator having one end open and the other end grounded on the surface of a base made of an insulator. An electrode, a surface-mounted antenna formed with a feed electrode spaced apart from the radiation electrode, and a monopole antenna arranged near the surface-mounted antenna, wherein the surface-mounted antenna and the monopole antenna Are supplied from the same feeding point, and the image current of the current flowing through the surface-mounted antenna is caused to flow through the monopole antenna, and the image current of the current flowing through the monopole antenna is arranged to flow through the surface-mounted antenna. It is characterized by the following.

Further, in the antenna device of the present invention, a strip-shaped radiation electrode having one open end and the other end being a ground end, and a feed electrode separated from the radiation electrode are formed on the surface of the base made of an insulator. And a monopole antenna disposed in the vicinity of the surface-mounted antenna. The surface-mounted antenna and the monopole antenna are fed from the same feeding point, and the surface-mounted antenna is The direction of the open end with respect to the ground end of the radiation electrode of the antenna and the direction of the open end with respect to the feed point of the monopole antenna are arranged so as to be opposite to each other. .

Further, in the antenna device according to the present invention, the electric length of the monopole antenna is reduced to 1/8 at a used frequency.
The wavelength is set to 1/4 wavelength.

A communication device according to the present invention uses any one of the above antenna devices.

With such a configuration, the antenna device of the present invention can improve the gain and reduce the characteristic change depending on the place where the antenna device is placed.

Further, the communication device of the present invention can improve the characteristics.

[0019]

FIG. 1 shows an embodiment of an antenna device according to the present invention. Here, FIG. 1A is a diagram viewed from one main surface 2a side of the mounting substrate 2, and FIG. 1B is a diagram viewed from the other main surface 2b side of the mounting substrate 2. In FIG. 1, FIG.
The same or equivalent portions as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.

In the antenna device 20 shown in FIG.
A ground electrode 21 is formed on the other main surface 2 b of the mounting substrate 2, and a feeder wiring 22 is formed on a corner portion of the other main surface 2 b of the mounting substrate 2, at a removed portion 21 a of the ground electrode 21. Has been implemented. The power supply end 23 a of the monopole antenna 23 is connected to the power supply wiring 22. The power supply wiring 4 formed on the one main surface 2a of the mounting substrate 2 and the power supply wiring 22 formed on the other main surface 2b of the mounting substrate 2 are connected to each other through a through hole 24. Here, since the power supply wiring 4 is connected to the signal source 6, the surface mount antenna 5 and the monopole antenna 23 are connected.
Are supplied from the same power supply point. And
The surface-mounted antenna 5 and the monopole antenna 23 have a direction of an open end 11a with respect to a ground end of the radiation electrode 11 of the surface-mount antenna 5 and an open end 23b with respect to a feed end 23a of the monopole antenna 23. Are arranged so as to be opposite to each other.

In the antenna device 20 configured as described above, when the current 19 flows through the surface-mount type antenna 5, the current 25 also flows through the monopole antenna 23 which is fed simultaneously. And the surface mount antenna 5 is
Power is supplied via a capacitance formed between the power supply electrode 13 and the open end 11a of the radiation electrode 11, and the monopole antenna 23 is directly supplied with power to the power supply end 23a. The phases are opposite to each other.

Here, considering the surface mount antenna 5 as a reference, the image current of the current 19 flowing through the surface mount antenna 5 is the current 25 flowing through the monopole antenna 23.
, Both in direction and in phase. Therefore, the image current of the current 25 flowing through the surface mount antenna 5 does not flow much to the ground electrode 3, but mostly flows to the monopole antenna 23.

Conversely, considering the monopole antenna 23 as a reference, the image current of the monopole antenna 23, which would flow to the ground electrode 21 when operating alone, is equal to the current 19 flowing to the surface mount antenna 5. , Both in direction and in phase. Therefore, the monopole antenna 23
The image current of the current 25 flowing to the surface-mounting antenna 5 does not flow much to the ground electrode 21 but mostly flows to the surface-mount antenna 5.

As described above, the image current of the current 19 flowing through the surface mount antenna 5 and the monopole antenna 23
Flows through the ground electrode 3 and the ground electrode 21 of the mounting board 2.
As a result, even if the external environment using the antenna device 20 covered with a casing made of plastic or the like changes variously,
As a result, the location or direction of the image current of the current flowing through the surface mount antenna 5 or the monopole antenna 23 changes, and the characteristics of the antenna device 20 hardly change.

FIG. 2 shows the directivity of the return loss and the gain of the antenna device 20 according to the present invention between the antenna device when only a monopole antenna is mounted and the antenna device when only a surface mount antenna is mounted. Shown in comparison. Here, FIG. 2A shows the reflection loss of the antenna device when only the monopole antenna is mounted, FIG. 2B shows the directivity of the gain, and FIG. 2C shows only the surface mount type antenna. Figure 2 (d) shows the return loss of the antenna device when mounted.
2 also shows the directivity of the gain, FIG. 2E shows the reflection loss of the antenna device 20 of the present invention, and FIG. 2F shows the directivity of the gain. 2A, 2C, and 2E.
, BW1, BW2, and BW3 represent the bandwidth of the antenna device (the frequency band in which the reflection loss is −9.5 dB or less).

As can be seen from FIG. 2, the bandwidth of the antenna device of the present invention does not reach the overall balance when only a monopole antenna is mounted, but in particular, only the surface mount antenna is mounted on the high frequency side. It can be made wider than in the case where it is done. The directivity can also be eliminated by supplementing null points that appear near 0 and 180 degrees when only a monopole antenna is mounted with the directivity of the surface mount antenna. Further, the gain is 3.01 dBd at the maximum value and -3.19 dBd on average, and is -3.00 dB when only the monopole antenna is used on average.
-3.65 dB for Bd and surface mount antenna only
d, but the maximum value is 1.21 dB for each
d and 2.39 dBd.

As described above, the surface mount type antenna and the monopole antenna are combined to supply power from the same feeding point, and the direction of viewing the open end from the ground end of the radiation electrode of the surface mount type antenna, By arranging the antenna device with the direction in which the open end is viewed from the feed point being opposite to each other, both the bandwidth and the gain can be improved.

FIG. 3 shows a change in the maximum gain when the electrical length of the monopole antenna 23 of the antenna device 20 is changed. Here, the reference line r indicates the maximum gain of the antenna device 20 when only the surface mount antenna 5 is mounted.

According to FIG. 3, when the electric length of the monopole antenna 23 is １ ／ to 波長 wavelength, the maximum gain exceeds the reference line r. Thus, in the antenna device 20 of the present invention, the electric length of the monopole antenna is reduced to 1/8.
By setting the distance between the wavelength and the quarter wavelength, the gain can be improved as compared with the case where only the surface mount antenna 5 is mounted.

FIG. 4 shows another embodiment of the antenna device of the present invention. In FIG. 4, the view from the one main surface 2a side of the mounting board 2 is the same as FIG.
Is shown only from the other main surface 2b side. The same or equivalent parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 4, the monopole antenna 31 of the antenna device 30 is of a movable type that rotates 180 degrees with respect to a rotation axis 32. Here, FIG. 4A shows a state in which the monopole antenna 31 is protruded from the mounting board 2 (ie, the housing), and FIG. 4B shows a state in which the monopole antenna 31 is mounted on the mounting board 2 (ie, the housing). This shows the stored state. When the monopole antenna 31 is projected, the feeding end 3 of the monopole antenna 31
1 a is configured to be connected to the power supply wiring 22.

With such a configuration, the antenna device 30 of the present invention is in a state where the monopole antenna 31 is stored (in the case of a mobile phone, at the time of standby).
The monopole antenna 31 does not function, and only the surface mount antenna 12 functions as an antenna device. Then, when the monopole antenna 31 is protruded (at the time of a telephone call in the case of a mobile phone), the antenna device 30 functions as an antenna device combining the monopole antenna 31 and the surface mount antenna 12.

As described above, since the antenna device 30 is configured by combining the surface mount antenna 5 and the retractable monopole antenna 31, the monopole antenna 31 is stored, for example, when the mobile phone is on standby. Even if the antenna device 30 is dropped, it is possible to prevent the monopole antenna 31 from being damaged.

The method of storing the monopole antenna is not limited to the rotary type, but may be another type such as a telescopic type or a folding type.

In each of the above embodiments, the surface mount antenna 5 has a base made of a dielectric such as ceramics or resin, which is one of the insulators. The base may be constituted.

The monopole antenna is shown in FIGS.
The antenna is not limited to the linear antenna as shown in the embodiment of the present invention, but may be an antenna formed by spirally winding a radiation conductor such as a helical antenna, or an antenna combining a linear antenna and a helical antenna. The shape may be any.

FIG. 5 shows an embodiment of a communication device constructed using the antenna device 20 of the present invention. In FIG. 5, the communication device 40 has an antenna device 20 provided in a housing 41. The power supply wiring 4 formed on the mounting board 2 of the antenna device 20 is connected to a transmitting circuit 43 and a receiving circuit 44 via a switching circuit 42 also formed on the mounting board 2.

As described above, by configuring the communication device 40 using the antenna device 20 of the present invention, the bandwidth of the communication device 40 can be increased and the gain can be improved. Further, since the image current of the current flowing through the surface mount antenna 5 and the monopole antenna 23 mounted on the antenna device 20 hardly flows through the ground electrode 3 of the mounting board 2 and the housing of the communication device 40, the communication device 40 Even when the external environment in which the antenna is used changes, it is possible to prevent a change in antenna characteristics.

[0039]

According to the antenna device of the present invention, a strip-shaped radiation electrode having one end open and the other end grounded on the surface of the base made of an insulator, and a feed electrode separated from the radiation electrode The surface-mounted antenna and the monopole antenna are formed from the same feeding point, and the direction of the open end with respect to the ground end of the radiation electrode of the surface-mounted antenna and the power supply of the monopole antenna By arranging the direction of the open end with respect to the point so as to be opposite to each other, the image current of the current flowing through the surface-mount antenna flows through the monopole antenna and the image current of the current flowing through the monopole antenna To the surface mount antenna, and almost no image current flows to the ground electrode. Therefore, even if the external environment in which the antenna device is used changes, it is possible to prevent the characteristics of the antenna device from changing. Further, both the bandwidth and the gain of the antenna device can be improved.

Further, by increasing the electric length of the monopole antenna from ８ wavelength to １ ／ wavelength at the operating frequency, the gain of the antenna device is improved as compared with the case where only the surface mount antenna is mounted. Can be.

Further, by configuring a communication device using the antenna device of the present invention, the bandwidth of the communication device can be widened and the gain can be improved. Further, even if the external environment in which the communication device is used changes, it is possible to prevent a change in characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an antenna device of the present invention.

FIG. 2 is a diagram showing reflection loss and directivity of the antenna device of the present invention.

FIG. 3 is a diagram showing a relationship between an electrical length of a monopole antenna of the antenna device of the present invention and a maximum gain.

FIG. 4 is a diagram showing another embodiment of the antenna device of the present invention.

FIG. 5 is a perspective view showing one embodiment of the communication device of the present invention.

FIG. 6 is a diagram showing a conventional antenna device.

FIG. 7 is a perspective view showing a surface mount antenna used for the antenna device of FIG. 6;

[Explanation of symbols]

 Reference Signs List 2 mounting board 2a one main surface 2b other main surface 3, 21 ground electrode 3a, 21a ground electrode removing portion 4, 22 power supply wiring 5 surface mount antenna 6 signal source 19 surface mount type Antenna current direction 20, 30 Antenna device 23, 31 Monopole antenna 24 Through hole 25 Current direction of monopole antenna 32 Rotation axis

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Junichi Kurita 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Examiner at Murata Manufacturing Co., Ltd. Shintaro Kishida (56) References JP-A-9-270618 (JP, A JP-A-9-223916 (JP, A) JP-A-9-64624 (JP, A) JP-A-8-316716 (JP, A) Naohisa Goto, Science of Antennas, Kodansha, March 20, 1987, p. 96 (58) Field surveyed (Int. Cl. ⁷ , DB name) H01Q 1/24 H01Q 21/06-21/29

Claims (4)

(57) [Claims] 1. A surface-mounted antenna having a strip-shaped radiation electrode having one end open and the other end grounded on a surface of a base made of an insulator, and a feed electrode separated from the radiation electrode. And a monopole antenna disposed in the vicinity of the surface mount antenna. The surface mount antenna and the monopole antenna are fed from the same feeding point, and an image current of a current flowing through the surface mount antenna is provided. Is passed through the monopole antenna, and an image current of a current flowing through the monopole antenna is arranged to flow through the surface mount antenna. 2. A surface mount antenna comprising a strip-shaped radiating electrode having one end open and the other end grounded on a surface of a base made of an insulator, and a feed electrode separated from the radiating electrode. And a monopole antenna disposed in the vicinity of the surface-mounted antenna. The surface-mounted antenna and the monopole antenna are fed from the same feeding point, and the radiation electrode of the surface-mounted antenna is grounded. An antenna device, wherein a direction of an open end with respect to an end and a direction of an open end with respect to a feed point of the monopole antenna are arranged to be opposite to each other. 3. The antenna device according to claim 1, wherein the electric length of the monopole antenna is １ ／ to 波長 wavelength at a used frequency. 4. A communication device using the antenna device according to claim 1.