JP2008141627A - External antenna system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external antenna which can easily be attached to a radio communication device without needing any special structure on the radio communication device side and can improve antenna characteristics by obtaining excellent capacitive coupling with an incorporated antenna. <P>SOLUTION: A housing of the radio communication device is held by an attachment part, so that an antenna element electrically and physically connected to the relevant attachment part is attached to the housing. A mounting position of the attachment part is a position mutually opposed to the incorporated antenna within the housing. Thus, since the antenna element is attached to the housing via the attachment part in a fixed manner, excellent capacitive coupling is obtained on the basis of a fixed positional relationship between the relevant external antenna and the incorporated antenna, thereby improving the antenna characteristics. Furthermore, the housing of the radio communication device can easily be attached only by being held in the attachment part without providing any special structure for attaching the relevant external antenna to a side of the housing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is suitable for use in portable devices having a built-in antenna such as a mobile phone, a PHS phone (PHS: Personal Handyphone System), a PDA device having a wireless communication function (PDA: Personal Digital Assistant), or a portable game machine. The present invention relates to an external antenna device, and more particularly to an external antenna device that can be easily mounted on a portable device and can improve antenna characteristics.

  Nowadays, a mobile phone having a so-called built-in antenna provided in a housing is known. In recent years, the size and thickness of mobile phone cases have been reduced, and the built-in antenna is also reduced in size and built in in accordance with the reduced size and thickness of the case. It has become difficult to obtain.

  For this reason, a republished patent publication (Patent Document 1) of No. 03/021716 (International Publication No. WO2003 / 021716) discloses an “antenna device” for the purpose of improving antenna characteristics. . This antenna device is formed by weaving a linear conductor corresponding to a radio wave of a predetermined wavelength into a hand strap. By providing this hand strap in a wireless communication terminal, an external antenna is naturally attached to the wireless communication terminal. Is to be provided. The antenna characteristics are improved by electromagnetic coupling between the built-in antenna built in the wireless communication terminal and the external antenna of the hand strap.

No. 03/021716 (pages 10 to 11: FIGS. 1 and 3A)

  However, in the case of the antenna device disclosed in Patent Document 1, since the hand strap to be gripped by hand is an external antenna in the first place, if communication is performed by gripping the hand strap by hand during communication, There is a possibility that the antenna does not function effectively and good antenna characteristics cannot be obtained.

  In addition, when communication is performed without holding the hand strap by hand, the hand strap is shaken by movement of the user's body or hand, so the positional relationship between the external antenna and the built-in antenna is the hand strap. It is not stable and good electromagnetic coupling between the external antenna and the built-in antenna cannot be obtained, and there is a possibility that good antenna characteristics cannot be obtained.

  Further, in order to achieve electromagnetic coupling between the built-in antenna of the wireless communication terminal and the external antenna of the hand strap, the hand is placed at a special position of the wireless communication terminal so that the built-in antenna and the hand strap are close to each other. It is necessary to attach a strap. In other words, it is necessary to attach the hand strap to a position where it is not normally attached. Therefore, there is a problem that a special structure for attaching the hand strap to this special position is required on the wireless communication terminal side.

  The present invention has been made in view of the above-mentioned problems, and can be easily attached to the wireless communication device without requiring a special structure on the wireless communication device side. An object of the present invention is to provide an external antenna device that can obtain good antenna characteristics due to the fixed positional relationship between the two.

An external antenna device according to the present invention is an external antenna device provided in a wireless communication device provided with a built-in antenna provided in a housing, and as means for solving the above-described problem,
A mounting portion provided on the casing so as to face the built-in antenna in a manner covering the casing or sandwiching the casing;
And an antenna element that is electrically and physically connected to the mounting portion and that corresponds to the same frequency band as the built-in antenna.

  According to the present invention, the housing portion of the wireless communication device is covered with the mounting portion, so that the antenna element electrically and physically connected to the mounting portion is mounted on the housing through the mounting portion. . Alternatively, by holding the housing of the wireless communication device between the mounting portions, the antenna element electrically and physically connected to the mounting portion via the mounting portion is mounted on the housing. As a result, the antenna element can be easily attached to the case of the wireless communication device simply by covering the case with the case of the wireless communication device or simply holding the case of the wireless communication device with the attachment portion. be able to. For this reason, it is unnecessary to provide a special structure for mounting the external antenna device on the housing of the wireless communication device.

  In addition, the mounting portion is mounted so as to face the built-in antenna provided in the housing of the wireless communication device, and the antenna element is fixedly mounted to the housing via the mounting portion. A fixed positional relationship between the external antenna device and the built-in antenna can be established, and good antenna characteristics can be obtained.

  The present invention can be easily attached to the wireless communication device without requiring a special structure on the wireless communication device side. Also, good antenna characteristics can be obtained due to the fixed positional relationship with the built-in antenna.

  The present invention can be applied to an external antenna of a mobile phone having a so-called dual-band built-in antenna that transmits and receives radio waves in a frequency band of 800 MHz and a frequency band of 2 GHz, for example.

[Configuration of external antenna]
First, FIG. 1 (a) shows a view of the external antenna 1 according to the embodiment of the present invention as viewed from the back side, and FIG. 1 (b) shows a view of the back surface of the external antenna 1 as viewed obliquely. Show. As can be seen from FIGS. 1 (a) and 1 (b), the external antenna 1 includes a mounting portion 2 for mounting on a mobile phone, and a physical and electrical connection to the mounting portion 2. The first antenna element 3 and the second antenna element 4 are connected to each other.

  As an example, the overall width is about 100 mm, and the width of each antenna element 3, 4 is about 40 mm. The first antenna element 3 is an antenna element corresponding to the frequency band of 800 MHz and has a disk shape provided with a predetermined slit. The second antenna element 4 is an antenna element corresponding to the frequency band of 2 GHz, and has a disk shape having substantially the same diameter as the first antenna element 3.

The mounting portion 2 is formed by bending a rectangular flat plate member into a substantially “U” shape as shown in FIG. The width is slightly larger than the width of the mobile phone.

[Configuration of built-in antenna of mobile phone]
For example, a built-in antenna 10 shown in FIGS. 2 (a) and 2 (b) is housed in the casing of the mobile phone to which the external antenna 1 is mounted. 2A is a view of the built-in antenna 10 as viewed from the front, and FIG. 2B is a perspective view of the built-in antenna 10.

  As can be seen from FIGS. 2A and 2B, the built-in antenna 10 includes a first antenna element 11 corresponding to a frequency band of 800 MHz and a second antenna element 12 corresponding to a frequency band of 2 GHz. This is a so-called dual-band built-in antenna. The built-in antenna 10 has a feeding point 13 for supplying power to the built-in antenna 10.

This built-in antenna 10 is provided in the vicinity of the upper end portion on the back side of the mobile phone (= in the vicinity of the upper end portion of the surface opposite to the surface on which the display portion of the mobile phone is provided).

[Attaching an external antenna to a mobile phone]
Next, FIG. 3A is a view of the mobile phone with the external antenna 1 attached as viewed from the back side of the mobile phone, and FIG. 3B is the mobile phone with the external antenna 1 attached. The figure which looked at from the front side of the said mobile telephone is shown. As can be seen from FIGS. 3A and 3B, when the external antenna 1 is attached to the mobile phone 20, the horizontal width of the mounting portion 2 of the external antenna 1 and the horizontal width of the mobile phone 20 are matched, The external antenna 1 is attached to the mobile phone 20 in such a manner that the casing of the mobile phone 20 is pushed into the gap of the mounting portion 2 that is bent into a substantially “U” shape. Thus, the external antenna 1 can be easily attached to the mobile phone 20 with one touch without providing a special structure for attaching the external antenna 1 on the housing side of the mobile phone 20.

  As described above, the width of the mounting portion 2 is slightly larger than the width of the mobile phone 20. For this reason, when the external antenna 1 is attached to the mobile phone 20, the external antenna 1 is fixed and attached to the mobile phone 20 in such a manner that the housing of the mobile phone 20 is sandwiched between the attachment portions 2. Become. The portion where the external antenna 1 is mounted is a portion where the built-in antenna 10 of the mobile phone 20 is provided. Further, the portion where the external antenna 1 is attached is in the vicinity of the feeding point 13 of the built-in antenna 10 of the mobile phone 20 and is a portion where a large current flows. For this reason, by attaching the external antenna 1 to the mobile phone 20, the internal antenna 10 and the mounting portion 2 are in a mutually opposing positional relationship, and good capacitive coupling between the external antenna 1 and the internal antenna 10 can be obtained. Become.

As a result, each antenna element 3, 4 provided in the mounting portion 2 is fixedly mounted to the mobile phone 20 via the mounting portion 2, and the positional relationship facing the built-in antenna 10 is established. In addition to being able to be held stably, by maintaining a stable positional relationship between the two, it is possible to obtain a stable capacitive coupling between the external antenna 1 and the built-in antenna 10 in the mobile phone 20, and thus a good antenna Characteristics can be obtained.

[Improving antenna characteristics by attaching external antennas]
FIG. 4 shows antenna characteristics measured by the applicant of the present invention by making a prototype of such an external antenna 1 and mounting it on the mobile phone 20. The measurement result shown in FIG. 4 is a measurement result obtained by placing the mobile phone equipped with the external antenna 1 as shown in FIG. 5 in a normal call state in free space.

  In the graph of antenna characteristics shown in FIG. 4, the horizontal axis is GSM (Global System for Mobile Communications), DCS (DCS: Digital Communications System), PCS (PCS: Personal Communication Services), and UMTS (UMTS: The frequency band used in each communication system (Universal Mobile Telecommunications System), and the vertical axis represents the radiation efficiency (dB). Further, in FIG. 4, the graph indicated by the dotted line indicates the radiation efficiency of only the built-in antenna 10 in each communication method, and the graph indicated by the solid line indicates the radiation efficiency when the external antenna 1 is attached in each communication method.

  It can be seen from FIG. 4 that by attaching the external antenna 1 to the mobile phone 20, good radiation efficiency can be obtained in any frequency band used in each communication method. In particular, in the GSM 900 MHz band, an improvement in radiation efficiency of 6.5 dB could be obtained.

When the external antenna 1 is attached to the mobile phone 20, the antenna elements 3 and 4 are located outside the casing of the mobile phone 20. In addition, since the antenna elements 3 and 4 have a planar shape (or may be a linear shape), the current flowing through the ground is reduced. Therefore, good antenna characteristics can be obtained even when the human body is close as shown in FIG.

[Modification of mounting part]
The mounting portion 2 shown mainly in FIG. 1 (b) was bent into a substantially “U” shape. The shape of the mounting portion 2 is as shown in FIG. 6 (a). It is good also as a shape bent into substantially "C-shape". In this case, when the external antenna 1 is attached to the mobile phone 20, the case of the mobile phone 20 can be sandwiched from the front, rear, left, and right surfaces by the mounting portion 2 having a “C-shape”. The external antenna 1 can be attached to the mobile phone 20 more stably.

In addition, as the shape of the mounting portion 2, as shown in FIG. In this case, the external antenna 1 is attached to the mobile phone 20 in such a manner that the upper end portion of the mobile phone 20 is inserted into the gap 40 of the mounting portion 2. Thereby, the housing of the mobile phone 20 can be clamped more firmly from the front, rear, left and right surfaces, and the external antenna 1 can be attached to the mobile phone 20 more stably. .

[Modification of antenna element]
In the case of the example shown in FIGS. 1A and 1B, a slit is provided in the first antenna element 3, but this is not the case with the second antenna as shown in FIG. 7A. A slit may be provided for the element 4. In this case, the first antenna element 3 corresponds to the frequency band of 2 GHz, and the second antenna element 4 corresponds to the frequency band of 800 MHz.

  Further, as shown in FIG. 7B, a slit may be provided for each of the first antenna element 3 and the second antenna element 4. That is, the slit is provided according to the frequency band to be transmitted / received.

  In addition, in the case of the example shown in FIGS. 1A and 1B, two antenna elements 3 and 4 for each frequency band are provided in order to support the dual band, but only the single band is supported. In that case, it is only necessary to provide one antenna element as shown in FIG. Similarly, when the triple band is supported, three antenna elements corresponding to each frequency band may be provided.

  In the case of the example shown in FIGS. 1A and 1B, each antenna element 3 and 4 has a disc shape, but this is a linear shape or shown in FIG. 7D. It is good also as a spiral shape. In this case, the antenna element is positioned in a direction away from the human body during a call, so that even better antenna characteristics can be obtained.

  In the example shown in FIGS. 1 (a) and 1 (b), each antenna element 3 and 4 has a disc shape, but this is a semi-elliptical shape as shown in FIG. 7 (e). It is good also as a shape.

  Further, in the example shown in FIGS. 1A and 1B, a slit is provided on the antenna element side, but this is a slit with respect to the mounting portion 2 as shown in FIG. 7F. May be provided.

That is, the shape of the antenna element, the number provided, the presence / absence of a slit, the position where the slit is provided, etc. Adjust it.

[Effect of the embodiment]
As is clear from the above description, the external antenna of this embodiment is electrically connected to the mounting unit 2 via the mounting unit 2 by sandwiching the casing of the mobile phone 20 with the mounting unit 2. The physically connected antenna elements 3 and 4 are attached to the casing. Alternatively, by covering the mounting portion 2 on the casing of the mobile phone 20, the antenna elements 3 and 4 electrically and physically connected to the mounting portion 2 are mounted on the casing via the mounting portion 2. .

  Accordingly, the external antenna 1 can be easily attached to the casing of the mobile phone 20 simply by holding the casing of the mobile phone 20 with the mounting portion 2 or covering the mounting portion 2 with the casing of the mobile phone 20. Can be attached to. For this reason, it is not necessary to provide a special structure for mounting the external antenna 1 in the casing of the mobile phone 20.

  The mounting unit 2 is mounted so as to face the built-in antenna 10 provided in the casing of the mobile phone 20, and the antenna elements 3 and 4 are connected to the casing through the mounting unit 2. Since it is fixedly mounted, a fixed positional relationship between the external antenna 1 and the built-in antenna 10 can be established, and good antenna characteristics can be obtained.

  In the above description of the embodiment, the present invention is applied to an external antenna of a mobile phone. However, the present invention has a PHS phone (PHS: Personal Handyphone System) and a wireless communication function. The present invention can also be applied to an external antenna of another portable device such as a PDA device (PDA: Personal Digital Assistant), a portable game machine, and a portable television receiver. In any case, the same effect as described above can be obtained.

  For example, the external antenna 1 may be covered with a cover that represents the face of a character such as an animal, a virtual animal, a manga or a game. In this case, it is preferable that the cover member is formed of a member that does not adversely affect communication such as felt. Thereby, the external antenna 1 can be used as an accessory.

  Further, a strap attachment member may be provided on the external antenna 1. As a result, the external antenna 1 can be attached to the portable strap attached to the mobile phone and made portable via the strap attachment member.

  Finally, the present invention is not limited to the above-described embodiment, which is disclosed only as an example of the present invention. For this reason, as long as it is the range which does not deviate from the technical idea which concerns on this invention, it adds that it is needless to say that various changes are possible according to a design etc. also except the above-mentioned embodiment. .

It is a figure which shows the shape which looked at the external antenna used as embodiment which applied this invention from the back surface, and the shape seen from diagonally. It is a figure which shows the shape which looked at the internal antenna provided in the housing | casing of a mobile telephone from the front, and the shape seen from diagonally. It is the figure which looked at the state which attached the external antenna used as an embodiment to a cellular phone from the back side and the front side of the cellular phone concerned. It is a figure which shows an example of the antenna characteristic of the external antenna used as embodiment. It is a figure for demonstrating the measurement condition of the antenna characteristic of the external antenna used as embodiment. It is a figure for demonstrating the modification of the mounting part of the external antenna used as embodiment. It is a figure for demonstrating the modification of the antenna element of the external antenna used as embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 External antenna 2 Mounting part of external antenna 3 1st antenna element for frequency band of 800 MHz, 2nd antenna element for frequency band of 42 GHz, 10 built-in antenna of mobile phone, 11 built-in antenna 800 MHz frequency band first antenna element, 12 built-in antenna 2 GHz frequency band second antenna element, 13 built-in antenna feed point, 20 mobile phone

Claims (3)

An external antenna device provided in a wireless communication device provided with a built-in antenna provided in a housing,
A mounting portion provided on the casing so as to face the built-in antenna in a manner covering the casing or sandwiching the casing;
An external antenna device comprising: an antenna element that is electrically and physically connected to the mounting portion and that corresponds to the same frequency band as the internal antenna. The external antenna device according to claim 1,
The external antenna device, wherein the mounting portion is provided in the housing so as to be close to a feeding point of the built-in antenna and to face the built-in antenna. The external antenna device according to claim 1 or 2,
The built-in antenna is compatible with multiple different frequency bands,
The antenna element is provided with an antenna element corresponding to any one of the plurality of frequency bands supported by the built-in antenna in the mounting portion, or the built-in antenna corresponds to the antenna element. An external antenna device characterized in that an antenna element corresponding to each frequency band is provided in the mounting portion.

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