JP2001274718A - Antenna system for portable mobile communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system for a portable mobile communication device that can prevent deterioration in radiation efficiency of a helical antenna caused on a human body. SOLUTION: The antenna system 11 of the portable mobile communication unit is provided with a case 12 and a printed circuit board 15, placed in the inside of the case 12 and on which various electronic components are mounted. The helical antenna 16 is mounted on the printed circuit board 15, a radiation conductor 1 is connected to a terminal 16d placed opposite to a feeding point in both terminals 16c, 16d of the helical antenna 16, and the radiation conductor 19 is placed at a position in the inside of the case 12 so as to be far from the body of the user. Through the use of such a configuration, the adverse effect by the human body can be reduced and the radiation efficiency of the helical antenna can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device of a portable mobile communication device suitable as a receiving antenna built in a portable telephone, for example.

[0002]

2. Description of the Related Art A helical antenna is an example of a receiving antenna built in a portable telephone. The helical antenna is an antenna having an antenna element formed by winding a conductor in a coil shape, and includes an air-core type (that is, a coil-shaped antenna alone),
There are one molded with resin and one with a chip multilayer type. Since the helical antenna can be configured to have a short overall length (that is, the actual length) of the antenna, the installation space can be reduced. In the helical antenna, the required length of the conductor of the antenna element can be sufficiently secured by adjusting the number of turns of the conductor, so that a high radiation efficiency of the antenna is obtained.

FIG. 4 shows an example of a configuration in which the helical antenna molded with a resin is mounted on a wiring board of a portable telephone. In FIG. 4, at a corner on the near side in FIG. 4 on the upper surface of the wiring board 1 of the mobile phone,
A helical antenna 2 is mounted. Various electronic components (not shown) are mounted on the upper surface of the wiring board 1, and these electronic components are covered and shielded by the shield case 3.

[0004]

When a user uses a mobile phone, the user's body is quite close to the wiring board 1 of the mobile phone. FIG. 5 shows a state in which the human body and the wiring board 1 approach each other. In FIG. 5, the human body of the user is shown as a pseudo human body 4,
The housing of the mobile phone is not shown. Then, in the state shown in FIG. 5, the helical antenna 2 approaches the human body 4 considerably.

[0005] Here, the radio wave propagates in space by generating an electric field between the antenna and GND (ground).
Also in the case of the helical antenna 2, an electric field is generated between the antenna element and GND (the wiring board 1 or the shield case 3) to propagate radio waves. But,
At this time, when the human body 4 exists near the helical antenna 2, the generated electric field is absorbed by the human body 4. As a result, apparently, the radiation efficiency of the helical antenna 2 is reduced.

In particular, in the case of the helical antenna 2 having the configuration shown in FIG.
Since the conductor is removed from all the layers (wiring layers) in the portion where is mounted, the electric field is generated equally on the human body 4 side and on the opposite side of the human body 4. At this time, the electric field generated on the side of the human body 4 is absorbed by the human body 4, so that the radiation efficiency near the human body 4 is further deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antenna device for a portable mobile communication device capable of minimizing a reduction in radiation efficiency of a helical antenna due to an adverse effect on a human body.

[0008]

According to the first aspect of the present invention, a radiating conductor is connected to a terminal of the helical antenna mounted on the wiring board, the terminal being opposite to the feeding point, Since the radiating conductor is arranged at a position far from the user's body inside the housing, it is possible to reduce the adverse effect of the human body and prevent the radiation efficiency of the helical antenna from lowering.

According to the second aspect of the present invention, the radiating conductor is disposed along the inner surface of the housing or in contact with the inner surface of the housing. Can be separated (avoided far away).

According to the third aspect of the present invention, since the radiation conductor is configured to be attached to the housing, the operation of attaching the radiation conductor is simplified, the productivity is improved, and the attachment strength of the radiation conductor is improved. Will be higher.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a receiving antenna device built in, for example, a portable telephone will be described below with reference to FIGS. First, FIG. 1 and FIG. 2 are diagrams partially showing a peripheral configuration of an antenna device 11 of a mobile phone. These FIGS. 1 and 2
As shown in FIG.
The upper case 13 and the lower case 14 are made of, for example, plastic.
A wiring board 15 of the mobile phone is housed inside the housing 12.

The wiring board 15 is composed of, for example, a printed wiring board, and various electronic components are mounted on both sides thereof. A helical antenna 16 is mounted on a front corner of the upper surface of the wiring board 15 in FIG. The helical antenna 16 has an antenna element 16a formed by winding a conductor in a coil shape.
Is molded with a resin 16b. And
The helical antenna 16 is a chip-shaped component having a substantially rectangular shape.
16d is provided.

The right terminal 16c of these two terminals 16c and 16d is a terminal that constitutes a feed point of the helical antenna 16, and the left terminal 16d is a terminal opposite to the feed point ( That is, an open-ended terminal). In this configuration, the helical antenna 16 is attached to the wiring board 15 by, for example, soldering the two terminals 16 c and 16 d to conductor patterns (lands) 17 and 18 provided on the wiring board 15. I have. In FIG. 2, two terminals 16c and 16d are shown in an emphasized manner.

An approximately L-shaped radiating conductor 19 composed of an elongated plate-shaped conductor is disposed on a portion of the wiring board 15 adjacent to the helical antenna 16. One end 19a of the radiation conductor 19 is soldered to a land 18a extending from the conductor pattern 18. Thus, the radiation conductor 19 is connected to the terminal 16 d of the helical antenna 16 and is attached to the wiring board 15. When the radiating conductor 19 is connected to the terminal 16d of the helical antenna 16 as described above, it appears that the length of the antenna element becomes longer, but this is due to the number of turns of the antenna element 16a of the helical antenna 16. By adjusting, it is possible to easily adjust to the optimal length dimension.

In the above mounting state, the radiation conductor 1
9 is in an upright state on the wiring board 15, and the other end 19 b of the radiation conductor 19 is connected to the wiring board 15.
Are in a substantially parallel state. In the case of this configuration, the other end 19b of the radiation conductor 19 is arranged along the inner surface of the upper case 13 of the housing 12, as shown in FIG. The other end 1 of the radiation conductor 19
9b may be arranged so as to contact the inner surface of the upper case 13.

Now, in the case of the above-mentioned portable telephone, the wiring board 1
5, a speaker, a microphone, a key portion, and the like are arranged on the lower surface side (that is, the lower case 14 side) in FIG. Thus, when the user uses the mobile phone, the user's head (that is, the human body) is moved to the lower case 1.
4 is applied to the outer surface. That is, the configuration is such that the human body is close to the lower surface side of the wiring board 15 in FIG.

When the usage pattern of the user is as described above, the other end 19b of the radiation conductor 19 is
2, the distance between the other end 19b of the radiation conductor 19 and the human body (head) of the user is maximized. In other words, the radiation conductor 19 is configured to be disposed inside the housing 12 at a position farthest from the user's body.

Various electronic components (not shown) mounted on the upper surface of the wiring board 15 are covered and shielded by a shield case 20, as shown in FIG. In this case, the helical antenna 16 and the radiation conductor 19 are configured not to be covered by the shield case 20.

According to the present embodiment having such a configuration, of the two terminals 16c and 16d of the helical antenna 16 mounted on the wiring board 15, the terminal 1 on the opposite side to the feeding point is used.
6d, the radiation conductor 19 is connected, and the radiation conductor 19 is disposed in the housing 12 at a position away from the human body of the user, so that the adverse effect of the human body can be reduced, and the conventional configuration (FIG. 5), the radiation efficiency of the helical antenna 16 can be prevented from lowering.

In particular, in this embodiment, the other end 16b of the radiation conductor 16 is disposed along the inner surface of the upper case 13 of the housing 12, so that the radiation conductor 16 is It can be farthest from the human body. Therefore, the radiation efficiency of the helical antenna 16 can be improved accordingly.

Here, the measurement results of the radiation efficiency of the antenna device 11 of the present embodiment and the radiation efficiency of the helical antenna 2 of the prior art will be described with reference to FIGS. FIG. 3 shows an antenna device 11 of the present embodiment, and FIG. 4 shows a helical antenna 2 of a conventional configuration. In measuring the radiation efficiency, the XYZ axes are shown in FIGS.
The settings were as shown in FIG. That is, the X axis is a direction orthogonal to the plate surface of the wiring board 15, and the Y axis is a helical antenna 16.
Of the helical antenna 16
In the direction along the long side.

Then, in a state where the human body is brought close to each of the antenna devices of this embodiment and the conventional configuration (that is, a portable telephone incorporating each antenna device), the main polarization component on the YZ plane and the cross polarization on the YZ plane are set. Component, the main polarization component in the ZX plane,
The cross-polarization component on the ZX plane was measured. In this case, three frequencies (810.0 MHz, 826.5 MHz, 84
3.0 MHz), the above-mentioned respective polarization components were measured. Then, based on the above measurement results, the radiation efficiency (that is, the ratio of the power radiated by the antenna to the space with respect to the power input to the antenna) was calculated. Table 1 below shows the measurement results and calculation results according to the present embodiment.
Shown in

[0023]

[Table 1]

Table 2 below shows the measurement results and calculation results of the conventional configuration.

[0025]

[Table 2]

By comparing Tables 1 and 2, it is clear that the antenna device 11 of the present embodiment has higher radiation efficiency than the conventional configuration. That is, it can be seen that the antenna device 11 of the present embodiment can reduce the adverse effect on the human body more than the conventional configuration.

In the above embodiment, the radiation conductor 19 is constituted by a plate-like member, but may be constituted by a linear member instead. In the above embodiment, the radiation conductor 19
Although the shape of the shape is substantially L-shaped, the shape is not limited to this, and any straight shape, curved shape, U-shaped shape, crank-shaped shape, etc. It may be formed in such a free shape.

Further, in the above-described embodiment, the radiation conductor 19 is configured to be mounted on the wiring board 15 by soldering. Instead, the radiation conductor 19 is configured to be mounted on a casing, for example, an upper case. May be. In the case of this configuration, a configuration is preferable in which a housing recess is formed in the upper case, and a radiation conductor is fitted and fixed in the housing recess. In connecting one end of the radiation conductor to the land of the wiring board, for example, a pin is extended and protruded from the land of the wiring board via a spring, and one end of the radiation conductor is pressed into contact with this pin. It is preferable to configure. In this manner, when the radiation conductor is attached to the housing, the operation of attaching the radiation conductor is simplified, the productivity is improved, and the attachment strength of the radiation conductor is increased.

In the above-described embodiment, the helical antenna 16 is a resin-molded antenna. However, the present invention is not limited to this. An air-core antenna (ie, a coil-shaped antenna unit) is used. Alternatively, a chip multilayer type may be used. In the above embodiment, the present invention is applied to a mobile phone. However, the present invention may be applied to another portable mobile communication device.

[Brief description of the drawings]

FIG. 1 is a perspective view of the vicinity of an antenna device according to an embodiment of the present invention.

FIG. 2 is a partial longitudinal sectional view around an antenna device.

FIG. 3 is a diagram for explaining XYZ axes for measuring radiation efficiency.

FIG. 4 is a diagram corresponding to FIG. 3, showing a conventional configuration.

FIG. 5 is a diagram for explaining an adverse effect on a human body;

[Explanation of symbols]

11 is an antenna device, 12 is a housing, 13 is an upper case, 1
4 is a lower case, 15 is a wiring board, 16 is a helical antenna, and 19 is a radiation conductor.

Claims (3)

[Claims] 1. An antenna device for a portable mobile communication device, comprising: a housing; and a wiring board provided inside the housing and mounted with various electronic components, wherein the antenna device is mounted on the wiring board. A helical antenna, and a radiating conductor connected to a terminal of the two terminals of the helical antenna opposite to the feeding point, wherein the radiating conductor is provided inside the housing in the portable mobile object. An antenna device for a portable mobile communication device, wherein the antenna device is disposed at a position far from a human body of a user who uses the communication device. 2. The portable mobile communication according to claim 1, wherein the radiating conductor is disposed along the inner surface of the housing or in contact with the inner surface of the housing. Machine antenna device. 3. The antenna device for a portable mobile communication device according to claim 1, wherein the radiation conductor is configured to be attached to the housing.