JP2004320520A - Portable radio device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable radio device which can transmit/receive radio waves of a plurality of frequency bands and whose antenna characteristics are improved much more. <P>SOLUTION: The device is provided with a double resonance antenna 4 transmitting/receiving the radio waves of the first frequency band and the second frequency band; an antenna matching circuit 3 matching the radio wave to the first frequency band and the second frequency band; a first parasitic element 5 resonating to the radio wave of the first frequency band, a second parasitic element 6 resonating to the radio wave of the second frequency band; and a change-over switch 7 which connects the first parasitic element 5 to ground potential when the frequency of the radio wave transmitted/received by the double resonance antenna 4 is applied to the first frequency band, and connects the second parasitic element 6 to ground potential when the frequency of the radio wave transmitted/received by the double resonance antenna 4 is applied to the second frequency band. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a portable wireless device such as a mobile phone.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a mobile phone that is a kind of a mobile wireless device includes, for example, a dual-band compatible device capable of transmitting and receiving radio waves in two frequency bands, a GSM (Global System for Mobile Communication) band and a DCS (Digital Cellular System) band. is there. In addition, there is a triple band compatible device that can transmit and receive radio waves in three frequency bands including a W-CDMA (Wideband Code Division Multiple Access) band in addition to the above two frequency bands. Some of these mobile phones are provided with one multi-resonant antenna and an antenna matching circuit corresponding to the frequency band so as to support the plurality of frequency bands (for example, see Patent Document 1). In this case, the antenna matching circuit is selected according to the frequency band of the radio wave to be transmitted and received.
[0003]
[Patent Document 1]
JP 10-145262 A
[Problems to be solved by the invention]
In the above-described conventional technique, when a plurality of antenna matching circuits are provided, a switch is provided on a high-frequency signal line between the antenna and the multi-resonant antenna for transmitting / receiving a signal using a high-frequency radio wave for selecting an antenna matching circuit. For this reason, there is a possibility that the characteristics of the switch may be degraded due to a switch insertion loss or multi-resonance of the antenna.
[0005]
The present invention has been made in order to solve the problems of the conventional technology as described above, and it is an object of the present invention to provide a portable wireless device capable of transmitting and receiving radio waves in a plurality of frequency bands and having improved antenna characteristics. Aim.
[0006]
[Means for Solving the Problems]
A portable wireless device of the present invention for achieving the above object has a multiple resonance antenna capable of transmitting and receiving radio waves in a first frequency band and a second frequency band different from the first frequency band;
An antenna matching circuit matched to the first frequency band and the second frequency band;
A first parasitic element that resonates with the radio wave of the first frequency band;
A second parasitic element that resonates with the radio wave of the second frequency band;
When the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the first frequency band, the first parasitic element is connected to the ground potential, and the frequency of the radio wave transmitted and received by the multiple resonance antenna is the second frequency band. A changeover switch for connecting the second parasitic element to a ground potential when the frequency band of
It is a structure which has.
[0007]
In the present invention, since the parasitic element in the frequency band corresponding to the transmitted / received radio wave is grounded, the radiation current due to the radio wave flows to the ground via the parasitic element, and the antenna characteristics are improved. Further, not only is it unnecessary to provide a plurality of antenna matching circuits, but also a switch for switching the antenna matching circuit is not required in the high-frequency signal line between the multiple resonance antenna and the antenna matching circuit, so that a switch is inserted in the high-frequency signal line. Loss can be reduced.
[0008]
Further, in the portable wireless device of the present invention, at least one of the first parasitic element and the second parasitic element includes:
It may have any one of a coiled conductor, an L-shaped conductor, and a conductor plate.
[0009]
In the present invention, at least one of the two parasitic elements can be selected from the coiled conductor, the L-shaped conductor, and the conductor plate in accordance with the housing of the portable wireless device.
[0010]
Further, in the portable wireless device of the present invention, one of the first parasitic element and the second parasitic element may be provided outside a housing, and the first parasitic element may be provided outside the housing. The power feeding element and the second parasitic element may be provided outside the housing.
[0011]
According to the present invention, one of the two parasitic elements can be installed outside according to the empty space inside the housing or the directivity of radio waves. The housing of the machine can be made more compact.
[0012]
Further, the portable wireless device of the present invention includes a multiple resonance antenna capable of transmitting and receiving radio waves in a first frequency band and a second frequency band different from the first frequency band;
An antenna matching circuit matched to the first frequency band;
A parasitic element that resonates with the radio wave of the second frequency band,
When the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the first frequency band, the parasitic element is separated from the ground potential, and the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the second frequency band. A changeover switch for connecting the parasitic element to a ground potential when
It is a structure which has.
[0013]
According to the present invention, when the radio wave transmitted and received by the multiple resonance antenna is a radio wave in the second frequency band, the parasitic element is grounded, so that the radiated current due to the radio wave flows to the ground via the parasitic element, thereby improving the antenna characteristics. I do. Further, not only is it unnecessary to provide a plurality of antenna matching circuits, but also a switch for switching the antenna matching circuit is not required in the high-frequency signal line between the multiple resonance antenna and the antenna matching circuit, so that a switch is inserted in the high-frequency signal line. Loss can be reduced. Further, since no parasitic element that resonates with radio waves in the first frequency band is not provided, the number of parasitic elements can be reduced, and the size of the portable wireless device can be further reduced.
[0014]
Further, in the portable wireless device according to the present invention, the parasitic element may include:
It may have any one of a coiled conductor, an L-shaped conductor, and a conductor plate.
[0015]
According to the present invention, the parasitic element can be selected from any of a coiled conductor, an L-shaped conductor, and a conductor plate according to the case of the portable wireless device.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The portable wireless device according to the present invention is characterized in that a parasitic element connectable to a ground potential is provided corresponding to a frequency band.
[0017]
(First embodiment)
A portable wireless device according to the present embodiment will be described. In the following, it is assumed that the portable wireless device can support two frequency bands of a first frequency band and a second frequency band different from the first frequency band. In addition, a configuration for a call provided in a normal portable wireless device is the same as that of the conventional one, and a description thereof will be omitted.
[0018]
As shown in FIG. 1, a portable wireless device 1 according to the present invention includes a multiple resonance antenna 4 for transmitting and receiving radio waves in a plurality of frequency bands, and an antenna matching matched to a first frequency band and a second frequency band. A circuit 3; a radio circuit 2 for amplifying a radio wave received from the antenna matching circuit 3; and a first parasitic power for flowing a radiation current by the radio wave to a housing ground (ground) to which the multiple resonance antenna 4 is connected. A configuration including an element 5 and a second parasitic element 6, a changeover switch 7 for switching the connection of these two parasitic elements to the housing ground, and a control unit 8 for sending a control signal to the changeover switch 7 It is.
[0019]
The first parasitic element 5 and the second parasitic element 6 are each formed by winding a conductive wire in a coil shape. The conductor of the first parasitic element 5 has a length that resonates with radio waves in the first frequency band, and the conductor of the second parasitic element 6 has a length that resonates with radio waves in the second frequency band. The length of the conductor is, for example, １ ／ of the wavelength of the representative frequency in the corresponding frequency band.
[0020]
The control unit 8 has a CPU (not shown) for executing predetermined processing according to a program, and a memory (not shown) for storing the program.
[0021]
When the frequency of the radio wave transmitted and received falls in the first frequency band, the control unit 8 switches the changeover switch 7 to connect the first parasitic element 5 to the housing ground. Thereby, the radiation current of the radio wave to be transmitted and received flows to the housing ground via the first parasitic element 5. Therefore, the antenna characteristics of the multiple resonance antenna 4 are improved, and the transmission / reception characteristics of the radio wave in the first frequency band are improved. In this case, the second parasitic element 6 does not operate because it is separated from the housing ground.
[0022]
On the other hand, when the frequency of the transmitted / received radio wave corresponds to the second frequency band, the control unit 8 switches the changeover switch 7 to connect the second parasitic element 6 to the housing ground. As a result, the radiation current of the transmitted / received radio wave flows to the housing ground via the second parasitic element 5. For this reason, the antenna characteristics of the multiple resonance antenna 4 are improved, and the transmission and reception characteristics for radio waves in the second frequency band are further improved. In this case, the first parasitic element 5 does not operate because it is disconnected from the housing ground.
[0023]
As described above, the portable wireless device of the present invention includes a parasitic element that resonates with the transmitted / received radio wave for each frequency band, and grounds the parasitic element corresponding to the frequency band of the transmitted / received radio wave, thereby providing a passive element for each frequency band. Optimum antenna characteristics can be obtained.
[0024]
In addition, it is not necessary to provide a plurality of antenna matching circuits, and a switch for switching the antenna matching circuit is not required in the high-frequency signal line, thereby reducing a switch insertion loss in the high-frequency signal line and expanding a desired frequency band. Thus, the effect of improving the antenna characteristics can be obtained.
[0025]
Although the case where there are two frequency bands that can be transmitted and received has been described, three or more frequency bands may be used. When there are three or more frequency bands, a parasitic element corresponding to the frequency band is provided, and the changeover switch 7 is switched according to the frequency band of the radio wave to be transmitted and received, as in the above two cases. Just fine.
[0026]
Further, the case has been described where the first parasitic element 5 and the second parasitic element 6 are coil-shaped conductors. However, the present invention is not limited to the coil-shaped conductor, and may be configured as described below. .
[0027]
FIG. 2 is a schematic diagram illustrating another configuration example of the parasitic element.
[0028]
In FIG. 2A, the conductor of the second parasitic element 6 shown in FIG. 1 is L-shaped. In FIG. 2B, the second parasitic element 6 shown in FIG. 1 is a conductive plate. According to the housing of the portable wireless device, any one of a coiled conductor, an L-shaped conductor, and a plate conductor can be selected as the parasitic element. Here, another configuration example of the second parasitic element 6 has been described, but the first parasitic element 5 may have any configuration of a coiled conductor, an L-shaped conductor, and a plate conductor. .
[0029]
(Second embodiment)
In the present embodiment, the first parasitic element 5 in the first embodiment is omitted by more matching the antenna matching circuit to the first frequency band among the plurality of frequency bands.
[0030]
A configuration example of the portable wireless device according to the present embodiment will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Further, as in the first embodiment, it is assumed that the portable wireless device can support two frequency bands of a first frequency band and a second frequency band.
[0031]
FIG. 3 is a block diagram illustrating a configuration of the portable wireless device of the present embodiment.
[0032]
As shown in FIG. 3, the portable wireless device 10 of the present embodiment includes a multiple resonance antenna 4 and a wireless circuit 2 described in the first embodiment, an antenna matching circuit 13 matched to a first frequency band, and a multiple A second parasitic element 6 for flowing a radiation current of a radio wave to a housing ground to which the resonance antenna 4 is connected, and a changeover switch for switching the second parasitic element 6 between short-circuit and open of the housing ground. 17 and a control unit 18 that sends a control signal to the changeover switch 17.
[0033]
The control unit 18 has a CPU and a memory (not shown) as in the first embodiment. When the frequency of the radio wave to be transmitted and received falls in the first frequency band, the control unit 18 disconnects the second parasitic element 6 from the housing ground so that the second parasitic element 6 does not operate. The antenna matching circuit 13 can transmit and receive radio waves in the first frequency band.
[0034]
On the other hand, when the frequency of the transmitted / received radio wave corresponds to the second frequency band, the control unit 18 connects the second parasitic element 6 to the housing ground. Thereby, the radiation current of the radio wave to be transmitted and received flows to the housing ground via the second parasitic element 6. For this reason, the antenna characteristics of the multiple resonance antenna 4 are improved, and the transmission and reception characteristics for radio waves in the second frequency band are further improved.
[0035]
In the present embodiment, the same effects as in the first embodiment can be obtained, the number of parasitic elements can be reduced, and the size of the portable wireless device can be further reduced. This embodiment may also be applied to a portable wireless device capable of transmitting and receiving radio waves in three or more frequency bands, as in the first embodiment. Further, the second parasitic element 6 may have any configuration of a coil-shaped conductor, an L-shaped conductor, and a plate-shaped conductor.
[0036]
In the first and second embodiments, the control unit switches the changeover switch in accordance with the frequency band of the radio wave to be transmitted and received. However, the changeover switch may be changed over by the user.
[0037]
Further, both the first parasitic element 5 and the second parasitic element 6 may be provided outside the housing of the portable wireless device or may be provided inside. As shown in FIG. 1, the housing can be reduced in size by providing both of them outside. Further, as shown in FIG. 2B, either one may be provided inside and the other may be provided outside. In this way, the parasitic element can be installed according to the empty space inside the housing or the directivity of radio waves.
[0038]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0039]
According to the present invention, an optimum antenna characteristic can be obtained for each frequency band by providing a parasitic element that resonates with the transmitted / received radio wave for each frequency band and grounding the parasitic element corresponding to the frequency band of the transmitted / received radio wave.
[0040]
In addition, it is not necessary to provide a plurality of antenna matching circuits, and since a switch for switching the antenna matching circuit is not required in the high-frequency signal line, a switch insertion loss in the high-frequency signal line is reduced and a desired frequency band is expanded. Thus, the effect of improving the antenna characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a portable wireless device according to the present invention.
FIG. 2 is a schematic diagram illustrating another configuration example of the parasitic element.
FIG. 3 is a block diagram illustrating a configuration example of a portable wireless device according to a second embodiment.
[Explanation of symbols]
1, 10 Portable radio 2 Radio circuit 3, 13 Antenna matching circuit 4 Multiple resonance antenna 5 First parasitic element 6 Second parasitic element 7, 17 Changeover switch 8, 18 Control unit

Claims (6)

A multi-resonant antenna capable of transmitting and receiving radio waves in a first frequency band and a second frequency band different from the first frequency band;
An antenna matching circuit matched to the first frequency band and the second frequency band;
A first parasitic element that resonates with the radio wave of the first frequency band;
A second parasitic element that resonates with the radio wave of the second frequency band;
When the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the first frequency band, the first parasitic element is connected to the ground potential, and the frequency of the radio wave transmitted and received by the multiple resonance antenna is the second frequency band. A changeover switch for connecting the second parasitic element to a ground potential when the frequency band of
A portable radio having a. At least one of the first parasitic element and the second parasitic element,
The portable wireless device according to claim 1, further comprising any one of a coil-shaped conductor, an L-shaped conductor, and a conductor plate. One of the first parasitic element and the second parasitic element,
3. The portable wireless device according to claim 1, which is installed outside a housing. The first parasitic element and the second parasitic element,
3. The portable wireless device according to claim 1, which is provided outside the housing. A multi-resonant antenna capable of transmitting and receiving radio waves in a first frequency band and a second frequency band different from the first frequency band;
An antenna matching circuit matched to the first frequency band;
A parasitic element that resonates with the radio wave of the second frequency band,
When the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the first frequency band, the parasitic element is separated from the ground potential, and the frequency of the radio wave transmitted and received by the multiple resonance antenna falls in the second frequency band. A changeover switch for connecting the parasitic element to a ground potential when
A portable radio having a. The parasitic element,
6. The portable wireless device according to claim 5, comprising one of a coil-shaped conductor, an L-shaped conductor, and a conductor plate.

Images