JP2004241803A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus which reduces the cost while having a specified directivity and has no need of complicated adjustments. <P>SOLUTION: The radio communication apparatus (101) comprises a chip antenna (11) and a GND pattern (7), each having a length equal to approximately 1/4 of its operating frequency. The GND pattern (7) is disposed at a position shifted by a distance equal to approximately 1/2 of the operating frequency from the corner of a conductive frame (109) in the length direction of the frame (109) away from the chip antenna (11) and insulated from the frame (109).This constitution provides a directivity in a specific direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication device such as a personal computer and a PDA.
[0002]
[Prior art]
There is a wireless data transmission / reception system using a wireless communication device such as a personal computer. A typical example is a wireless LAN (Local Area Network) connecting personal computers. In a wireless LAN, for example, radio waves in the 5 GHz band are used, and an antenna for transmission and reception is mounted on a wireless communication device such as a personal computer. The mounted antenna is generally a chip antenna, and is mounted on an antenna mounting board.
[0003]
When it is desired to radiate a radio wave strongly in a specific direction using the above-described antenna mounting board (chip antenna), on the contrary, there is a case where it is particularly desired to receive only a radio wave coming from a specific direction. That is, there is a case where it is desired that the chip antenna has directivity. In such a case, an array antenna (arrayed antenna) has been used. The array antenna is an antenna that combines a plurality of chip antennas into one set of antennas, and combines the directivities of the chip antennas to obtain directivity in a specific direction as a whole antenna.
[0004]
[Problems to be solved by the invention]
However, an array antenna that requires a plurality of chip antennas requires more components and is more expensive than a single chip antenna, and the adjustment between chip antennas to obtain the required directivity is complicated. Etc. have a problem. Therefore, the cost of a wireless communication device equipped with such a chip antenna also increases, and complicated adjustment is required. The problem to be solved by the present invention is to provide a wireless communication device having an antenna mounting board which has directivity in a predetermined direction, is low in cost, and does not require complicated adjustment.
[0005]
[Means for Solving the Problems]
The inventor who made intensive studies to achieve the above object has succeeded in providing directivity in a predetermined direction by using a single antenna mounting board (chip antenna). If a single antenna mounting board is used, the cost can be suppressed and a complicated adjustment can be avoided as compared with a case where a plurality of antenna mounting boards are required. The detailed configuration will be described later. It should be noted that definitions of terms used in the description of the invention according to any one of claims are applied to inventions according to other claims to the extent possible in nature.
[0006]
(Characteristics of the invention described in claim 1)
A wireless communication device according to the first aspect of the present invention (hereinafter referred to as “the wireless communication device of the first aspect”) is connected to a chip antenna, a GND pattern juxtaposed to the chip antenna, and the chip antenna. A communication circuit and a conductive frame having a corner portion, wherein the chip antenna and the GND pattern are both formed to have a length equal to approximately １ ／ of the wavelength used; The chip antenna is disposed closer to the corner than the chip antenna, and at a position spaced apart from the corner in the longitudinal direction of the conductive frame by a distance equal to a length substantially equal to ２ of the wavelength used. , From the conductive frame. There is no limitation on the antenna structure of the chip antenna, and examples thereof include a whip antenna, an inverted L antenna, an inverted F antenna, other linear antennas, and planar antennas. A Bluetooth antenna or the like can also be suitably used.
[0007]
According to an experiment by the inventors using the wireless communication device according to claim 1, the causal relationship is being clarified by setting the relationship between the conductive frame and the chip antenna (antenna mounting board) to the relationship described above. However, directivity could be recognized in the length direction of the conductive frame (direction substantially parallel to the liquid crystal screen). Since it is only necessary to adjust the mounting position of the single antenna mounting board (chip antenna) on the conductive frame, it is possible to reduce costs and perform efficient communication without complicated adjustment.
[0008]
(Characteristics of the invention described in claim 2)
A wireless communication device according to the invention described in claim 2 (hereinafter, referred to as “wireless communication device of claim 2”) is the wireless communication device of claim 1, wherein the wireless communication device is provided between the chip antenna and the conductive frame. , And a linear GND electrically connected to the GND pattern is provided. The linear GND may be integrated with the GND pattern or may be separate from the GND pattern. In the former case, for example, a pattern can be formed together with the GND pattern using a conductive paste or the like. There is no limitation on the thickness (width) dimension of the linear GND. It may be thinner or thicker than the thickness of the chip antenna.
[0009]
According to the wireless communication apparatus of the second aspect, the effect of the linear GND is being clarified, but the influence of the conductive antenna on the chip antenna can be reduced. Therefore, the distance between the chip antenna and the conductive frame can be shortened, which contributes to downsizing of the antenna mounting board. Further, since the influence of the conductive frame is small, stable performance can be obtained even when the mounting environment changes.
[0010]
(Characteristics of the invention described in claim 3)
A wireless communication device according to a third aspect of the present invention is the wireless communication device according to the second aspect, wherein the linear GND is provided over the entire length of the chip antenna in the longitudinal direction.
[0011]
According to the wireless communication device of the third aspect, in addition to the operation and effect of the wireless communication device of the second aspect, since the linear GND is located between the chip antenna and the conductive frame in the longitudinal direction without any shortage, the conductivity is improved. The influence from the frame can be more reliably prevented.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a personal computer. FIG. 2 is a partially enlarged view of the antenna mounting board shown in FIG. FIG. 3 is a perspective view of the antenna mounting board shown in FIG. FIG. 4 is a front view when the mounting direction of the antenna mounting board shown in FIG. 2 is changed. 5 to 7 are diagrams showing the directivity of the antenna.
[0013]
(Schematic structure of wireless communication device)
A personal computer as an example of a wireless communication device will be described with reference to FIG. The personal computer 101 includes a computer main body 103 and a display unit 105 that opens and closes with respect to the computer main body 103. The display unit 105 has a rectangular liquid crystal screen 107 and a metal frame (conductive frame) 109 surrounding the liquid crystal screen 107. The conductive frame 109 is generally made of a metal such as aluminum, but may be made of another conductive material. The personal computer 101 is an example of a wireless communication device. In addition, there are various wireless communication devices such as a PDA (Personal Digital Aid). An antenna mounting board described below is mounted on the upper surface of the conductive frame 109, and the mounting position will be described later.
[0014]
(Schematic structure of antenna mounting board)
As shown in FIGS. 1 to 3, the antenna mounting substrate 1 includes a rectangular horizontally long ceramic or synthetic resin substrate 3. On one surface (mounting surface 5) of the substrate 3, the GND pattern 7 and the chip antenna 11 are juxtaposed along the longitudinal direction of the metal frame 109. The length of the chip antenna 11 (the length in the horizontal direction in FIG. 2) is set to a length substantially equal to the length of a quarter of the wavelength of the resonance frequency (used wavelength). In this embodiment, a dielectric antenna is used as the chip antenna 11. The reason why the dielectric antenna is used is that it is relatively advantageous for downsizing due to the relative permittivity of the dielectric, but other types of antennas may be used. Between the bottom 6 of the substrate 3 and the chip antenna 11 (along the bottom 6), it is preferable to form a linear GND 9 that is electrically connected to the GND pattern 7. It is effective that the length of the linear GND 9 is longer than the length of the chip antenna 11. By interposing the linear GND 9 over the entire length of the chip antenna 11, the chip antenna 11 is less likely to be affected by the metal frame 109. This point will be described in another section. The GND pattern 7 is not DC-connected to the metal frame 109, that is, is insulated from the metal frame 109. This is because, when connected, the electrical length of the GND pattern 7 changes due to the effect of the electrically integrated metal frame 109. The chip antenna 11 is connected to a communication circuit (not shown) built in the computer main body 103 via a coaxial cable 15.
[0015]
The GND pattern 7 and the linear GND 9 are integrally formed by applying a conductive paste on the mounting surface 5, but are formed by a method other than the conductive pattern, for example, a chemical method such as etching. May be. As a result of being formed integrally, the linear GND 9 has one end (the right end in FIG. 2) connected to the GND pattern 7 and the other end extending to the edge of the mounting surface 5. It is convenient to form the linear GND 9 integrally by the above-described method from the viewpoint of reducing the manufacturing labor. However, the linear GND 9 may be formed separately according to circumstances. In the case of a separate structure, one end is connected to the GND pattern 7 and the other end is left open. Further, the linear GND 9 may be formed by a method other than the conductive pattern. Instead of the conductive pattern, for example, there is a method of providing a linear GND such as a copper wire on the mounting surface 5. The length of the GND pattern 7 in the direction along the length direction of the upper surface of the metal frame 109 is set to be substantially equal to one-fourth of the used wavelength, similarly to the length of the chip antenna 11. There is no restriction on the selection of the resonance frequency, but in the present embodiment, a 5 GHz band usable for a wireless LAN is used.
[0016]
The chip antenna 11 is formed in a rectangular shape including one end face 11a located on the side of the GND pattern 7 and the other end face 11b located on the opposite side of the one end face 11a. The other end 9a on the opposite side is formed so as to cross a perpendicular L (see FIGS. 2 and 4) lowered to the base 6 through the other end face 11b. That is, only the linear GND 9 exists between the chip antenna 11 and the base 6. Although the causal relationship is being clarified, the provision of the linear GND 9 cuts off the coupling between the chip antenna 11 and the metal frame 109, whereby the chip antenna 11 (the antenna mounting board 1) is set on the metal frame 109. Instability at the time can be removed. That is, by providing the linear GND 9, the chip antenna 11 is probably isolated from the metal frame 109, and this isolation can cause a change in characteristics due to a shift in the relative position with respect to the metal frame when the same chip antenna 11 is used. It is thought that it is because it stops.
[0017]
(Antenna mounting board mounting position)
Next, the mounting position of the antenna mounting board 1 will be described with reference to FIGS. The antenna mounting substrate 1 is provided on the upper surface of the metal frame 109 with the mounting surface 5 standing upright. The reason why the mounting surface 5 is erected is to interpose the linear GND 9 between the chip antenna 11 and the metal frame 109. It may be attached to the upper surface of the horizontal portion of the metal frame 109 as shown in FIG. 2, or may be attached to the upper surface (side surface) of the vertical portion as shown in FIG. At this time, the antenna mounting board 1 is disposed at the end of the upper surface of the metal frame 109, that is, at a position where the distance between the corner and the chip antenna 11 is almost equal to の 長 of the used wavelength. The mounting of the antenna mounting board 1 to the metal frame 109 is performed via a mounting member not shown. However, the GND pattern 7 and the metal frame 109 are not connected in a DC manner. This is to thoroughly isolate the chip antenna 11 from the metal frame 109.
[0018]
(Experimental result)
The directivity of the antenna mounting board 1 (chip antenna 11) attached to the metal frame 109 will be described with reference to FIGS. FIG. 5 shows that the resonance frequency is 5.40 GHz, the length of the GND pattern 7 is set to 15 mm (λ / 4), and the distance from the chip antenna 11 to the corner of the metal frame 109 is 30 mm (λ / 2). 9 is a measurement result of directivity when the antenna mounting board 1 is attached so as to be as follows. FIG. 6 shows a case where the resonance frequency is 5.35 GHz, the length of the GND pattern 7 is set to 15 mm (λ / 4), and the distance from the chip antenna 11 to the corner of the metal frame 109 is λ / 2. Is a measurement result of directivity when the length is set to 20 mm, which is short. FIG. 7 shows a case where the resonance frequency is 5.2 GHz, the length of the GND pattern 7 is set to 25 mm longer than λ / 4, and the distance from the chip antenna 11 to the corner of the metal frame 109 is 30 mm. It is the measurement result of the directivity when it is. In each figure, 180 (deg) indicates a direction perpendicular to the back of the liquid crystal screen 107 of the personal computer 101 (a direction perpendicular to the back of FIG. 2), and 0 (deg) indicates a direction perpendicular to the surface of the liquid crystal screen 107. 2 shows a direction approaching the vertical direction (a vertical front direction from the surface in FIG. 2). Further, +90 (deg) indicates the left direction (arrow B direction) in FIG. 2 and -90 (deg) indicates the right direction (arrow F direction) in FIG. In each of the cases shown in FIGS. 5 to 7, the pattern (TX-V) indicated by the dotted line is the directivity pattern of the vertical polarization, and the pattern (TX-H) indicated by the solid line is the directivity pattern of the horizontal polarization. .
[0019]
First, when comparing the directivity shown in FIG. 5, the gain in the F direction is larger than the gain in the B direction by 10 dB or more, and the gain in the F direction and the gain in the 180 (deg) direction and the 0 (deg) direction are different. Compared with the gain, the former is about 8 to 10 dB, which is larger than the latter. In the directivity shown in FIG. 6, there is a portion where the directivity in the F direction is depressed by 2 to 3 dB as compared with the directivity shown in FIG. Therefore, it is understood that the directivity shown in FIG. 5 is more preferable than the directivity shown in FIG. The directivity shown in FIG. 7 is almost non-directional, and it can be seen that the front gain is inferior by 10 dB or more as compared with the directivity shown in FIG. From the above comparative study, the configuration for creating the directivity shown in FIG. 5, that is, as shown in FIGS. 2 and 4, the length of the GND pattern 7 is set to approximately λ / 4 of the resonance wavelength, and the chip antenna 11 and the metal It can be seen that it is preferable to attach the antenna mounting board 1 to the metal frame 109 so that the distance from the frame 109 is approximately λ / 2 of the resonance wavelength in order to obtain directivity in a specific direction.
[0020]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the wireless communication apparatus which concerns on this invention, while having directivity in a predetermined direction, cost is suppressed and complicated adjustment is unnecessary.
[Brief description of the drawings]
FIG. 1 is a front view of a personal computer (wireless communication device).
FIG. 2 is a partially enlarged view of the antenna mounting board shown in FIG.
FIG. 3 is a perspective view of the antenna mounting board shown in FIG. 2;
FIG. 4 is a front view when the mounting direction of the antenna mounting board shown in FIG. 2 is changed.
FIG. 5 is a diagram showing the directivity of an antenna.
FIG. 6 is a diagram showing the directivity of an antenna.
FIG. 7 is a diagram showing the directivity of an antenna.
[Explanation of symbols]
Reference Signs List 1 antenna mounting substrate 3 substrate 5 mounting surface 6 bottom 7 GND pattern 9 linear GND
11 chip antenna 101 personal computer (wireless communication device)
103 Computer body 105 Display 107 LCD screen 109 Metal frame (conductive frame)

Claims (3)

A chip antenna,
A GND pattern juxtaposed to the chip antenna;
A communication circuit connected to the chip antenna,
A conductive frame having a corner,
The chip antenna and the GND pattern are both formed to have a length equal to approximately の 長 of the wavelength used,
The GND pattern is arranged on the corner side of the chip antenna and at a position in the longitudinal direction of the conductive frame separated from the corner by a distance equal to approximately の 長 of the wavelength used. And a wireless communication device insulated from the conductive frame. The wireless communication device according to claim 1, further comprising a linear GND interposed between the chip antenna and the conductive frame and electrically connected to the GND pattern. The wireless communication device according to claim 2, wherein the linear GND is provided over the entire length of the chip antenna in the longitudinal direction.

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