JP2004228640A - Dielectric antenna and mobile communication apparatus incorporating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric antenna capable of performing transmission reception for three frequency bands even when the size is small. <P>SOLUTION: The dielectric antenna includes: a first linear element (11) located on an antenna forming face (9), extended adjacently to outer circumferences (9a, 9b, 9c, 9d) of the antenna forming face (9) and capable of being resonated with a first resonance frequency and a second resonance frequency corresponding to a harmonic mode of the first resonance frequency; and a second linear element (31) located on the antenna forming face (9), branched from the first linear element (11) via a branch part (33) and placed at an inner region of the antenna forming face (9), and the dielectric antenna can be resonated at the three resonance frequency bands by configuring the second linear element (31) so as to be resonated with a third resonance frequency other than the first resonance frequency and the second resonance frequency. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dielectric antenna built in a mobile communication device represented by a mobile phone, a portable wireless communication device, and the like, and a mobile communication device having a derivative antenna built therein.
[0002]
[Prior art]
2. Description of the Related Art With the spread of mobile communication devices in recent years, there has been a demand for a reduction in size and weight so as to be convenient when carrying or moving. Among electronic component groups built into such mobile communication devices, miniaturization of semiconductor integrated circuits and the like is rapidly progressing. Patent Literature 1 discloses a spiral or meandering element for reducing the size of an antenna.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-196339
[Problems to be solved by the invention]
However, when a spiral or meandering element is formed on a limited antenna formation surface, the elements are adjacent to each other, and thus mutual interference may occur due to capacitive coupling between the two elements. Mutual interference between the two elements should be avoided as much as possible, because it reduces the radiation efficiency of radio waves and hinders a wide band. The problem to be solved by the present invention is to solve the above-mentioned problem. By suppressing mutual interference between elements while being small, it is possible to reduce the radiation efficiency of radio waves and hinder broadband. It is an object of the present invention to provide a dielectric antenna which can be eliminated, and a mobile communication device incorporating such an antenna.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention has the following configuration. It should be noted that the definition of terms used in the description of the invention according to any one of the claims applies to the invention according to the other claims within the scope of its nature.
[0006]
(Characteristics of the invention described in claim 1)
The dielectric antenna according to the first aspect of the present invention includes a dielectric substrate having a rectangular antenna formation surface, a first resonance frequency extending on the antenna formation surface adjacent to an outer periphery of the antenna formation surface, and A first linear element capable of resonating at a second resonance frequency corresponding to a higher mode of the first resonance frequency, a power supply terminal connected to the first linear element base end, and a vicinity of the first linear element base end A linear conductor that branches from the first linear element on the antenna forming surface, a ground terminal connected to the distal end of the linear conductor, and a branch from the first linear element via the branch portion on the antenna forming surface. A second linear element located in an internal region of the antenna forming surface, and the second linear element is provided with a third common element other than the first resonance frequency or the second resonance frequency. Characterized in that it is resonating configured to be able to frequency.
[0007]
The dielectric antenna according to the first aspect is a so-called inverted-F antenna. The linear element resonates at the first resonance frequency, and the planar element resonates at the second resonance frequency. Since the linear element extends adjacent to the outer periphery of the rectangular antenna forming surface, an area (internal area) surrounded by the linear element on the antenna forming surface can be effectively used. In the dielectric antenna according to the first aspect, the first linear element resonates at the first resonance frequency and the second resonance frequency, and the second linear element resonates at the third resonance frequency. The second resonance frequency corresponds to a higher mode of the first resonance frequency, and the third resonance frequency is a resonance frequency other than the first resonance frequency or the second resonance frequency. The third resonance frequency may be a frequency lower than the first resonance frequency, a frequency between the first resonance frequency and the second resonance frequency, or a frequency higher than the second resonance frequency. Further, by setting the third resonance frequency near, for example, the second resonance frequency, the second resonance frequency can be substantially widened, or the three resonance frequencies can be independently made into a tri-band. can do.
[0008]
(Characteristics of the invention described in claim 2)
A dielectric antenna according to a second aspect of the present invention is the dielectric antenna according to the first aspect, wherein the first linear element includes a first bent portion located between a base end and an open end. It has a second bent portion and a third bent portion, and is located between the first bent portion and the second bent portion and between the third bent portion and the open end. And the return path is arranged substantially in parallel.
[0009]
According to the dielectric antenna of the second aspect, in addition to the operation and effect of the dielectric antenna of the first aspect, the direction of the high-frequency current flowing in the outward path is opposite to the direction of the high-frequency current flowing in the return path. Electromagnetic coupling occurs. By controlling the amount of coupling, the frequency of the higher-order mode moves. By utilizing this, the value of the second resonance frequency can be controlled. That is, for example, the value of the second resonance frequency can be adjusted by changing the length of the outward path without changing the entire length of the first linear element.
[0010]
(Characteristics of the invention described in claim 3)
A dielectric antenna according to a third aspect of the present invention is the dielectric antenna according to the second aspect, wherein the outward path portion is provided with a detour portion recessed in a direction toward an internal region of the antenna forming surface. And
[0011]
According to the dielectric antenna of the third aspect, in addition to the operation and effect of the dielectric antenna of the second aspect, the length of the return path can be shortened without changing the length of the first linear element due to the presence of the bypass. it can. When it is desired to shorten the length of the return path to change the second resonance frequency without changing the first resonance frequency, that is, to reduce the degree of coupling with the outward path, the first line is reduced by the length of the return path. The other parts of the element must be lengthened. The bypass has a function of absorbing the lengthened portion.
[0012]
(Characteristics of the invention described in claim 4)
According to a fourth aspect of the present invention, there is provided a mobile communication device including the dielectric antenna according to any one of the first to third aspects. Examples of the mobile communication device include a mobile phone and a small computer having a communication function.
According to the mobile communication device of the fourth aspect, the dielectric antenna according to any one of the first to third aspects is built in, and as described above, these dielectric antennas are smaller than the conventional one. It is planned. For this reason, a mobile communication device incorporating such a dielectric antenna can be reduced in size due to the reduced size of the dielectric antenna, in other words, the dielectric antenna can be incorporated even when there is only a small space. It becomes. Further, communication is possible in up to three frequency bands as required.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the dielectric antenna according to the present embodiment. FIG. 2 is an exploded perspective view of the dielectric antenna shown in FIG. FIG. 3 is a plan view in which the upper substrate of the dielectric antenna shown in FIG. 1 is omitted. FIG. 4 is a chart showing frequency characteristics. FIG. 5 is a front view of a small computer as an example of the mobile communication device.
[0015]
(Schematic structure of the first embodiment)
The dielectric antenna according to the first embodiment will be described with reference to FIGS. The dielectric antenna 1 includes a dielectric base 7 in which an insulating upper substrate 3 and a lower substrate 5 made of a dielectric ceramic material are laminated. Since the upper substrate 3 and the lower substrate 5 are formed in a rectangle (rectangle) of the same size when viewed in a plan view, the dielectric substrate 7 formed by laminating the two has a rectangular parallelepiped shape. The upper surface of the lower substrate 5 (the surface facing the lower surface of the upper substrate 3) forms an antenna forming surface 9 for forming an antenna. Since the lower substrate 5 is rectangular, the antenna forming surface 9 is also rectangular (rectangular). The reason why the dielectric substrate 7 is formed of a laminated body is that it is preferable to cover elements and the like (described later) formed on the lower substrate 5 with the upper substrate 3 in order to protect the elements and the like. Although the dielectric substrate 7 has a two-layer structure, the upper substrate 3 may be omitted to have a single-layer structure. Further, another layer substrate may be further laminated to form a structure of three or four or more layers. The reason why the dielectric substrate 7 is formed in the shape of a rectangular parallelepiped is to make it easy to obtain a large number of pieces by a so-called dicer cut or the like, and it is needless to say that the dielectric substrate 7 can be formed in other shapes.
[0016]
(Configuration of the first linear element)
As shown in FIGS. 2 and 3, on the antenna forming surface 9, a first linear element 11 adjacent to (along) the outer periphery (9a, 9b, 9c, 9d) of the antenna forming surface 9 is formed. It is convenient to form the first linear element 11 by printing a conductive paste, and leave a margin between the outer circumferences 9a, 9b, 9c, and 9d in order to absorb a printing shift at that time. It is preferable to keep it.
[0017]
As shown in FIGS. 2 and 3, the first linear element 11 includes a first portion 13, a third portion (outgoing portion) 14, a second portion 15, and a fourth portion (returning portion) 16. Here, the reason why the numbers are not arranged in order is that for convenience of explanation, and the fact that the numbers are not arranged does not affect the shape of the first linear element 11. The first portion 13 of the first linear element 11 is a portion located between the base end portion 12 and the first bent portion k1, and the third portion 14 is similarly formed by the first bent portion k1, the second bent portion k2, It is a part located between. Further, the second portion 15 is a portion located between the second bent portion k2 and the third bent portion k3, and the fourth portion 16 is similarly located between the third bent portion k3 and the open end 17. Part. In other words, the first portion 13 is adjacent to the outer periphery 9a, the third portion 14 is adjacent to the outer periphery 9b, the second portion 15 is adjacent to the outer periphery 9c, and the fourth portion 16 is adjacent to the outer periphery 9d. In addition, since each of the bent portions k1, k2, and k3 is located at each corner of the antenna forming surface 9, the first linear element 11 has its outer periphery 9a, 9b, It extends in an outer winding shape along 9c and 9d.
[0018]
Even when the first linear element 11 is formed on the antenna forming surface having the same area, the first linear element 11 may be formed on the first linear element having another shape which is not formed on the outer winding. This is because the circuit detours in comparison, and the length can be increased by the distance. As the length of the first linear element 11 increases, the resonance frequency decreases accordingly, and the antenna itself can be reduced in size. Further, by forming the first linear element 11 in an outer winding shape, a courtyard (margin surface) is formed in the antenna forming surface 9. If a second linear element described later is formed in the courtyard, the entire dielectric antenna 1 can be further reduced in size.
[0019]
When it is necessary to substantially increase the length of the first linear element 11, a detour portion 18 may be provided in the middle thereof, for example, in the third portion (outgoing portion) 14. This is because the length of the detour can be increased. Although the shape of the detour portion 18 is not limited, as shown in FIG. 3, it may be configured by a parallel portion 18 a substantially parallel to the outer periphery 9 b and step portions 18 b, 18 b at both ends thereof. This is because with this configuration, the erosion of the blank portion in the antenna forming surface 9 is relatively small.
[0020]
The base end 12 of the first linear element 11 is connected to a power supply terminal 19 formed on the end face of the dielectric substrate 7, as shown in FIGS. The power supply terminal 19 is generally formed by applying a conductive paste to the end face of the dielectric substrate 7.
[0021]
The first linear element 11 is formed to have a length capable of resonating with a first resonance frequency F1 (for example, 2.4 GHz band) and a second resonance frequency F2 (for example, 5.2 GHz band) which is a higher mode thereof. It is. The resonance frequency can be adjusted by shifting the position of the open end 17 in the left-right direction in FIG. 3, that is, by adjusting the total length of the first linear element 11. When resonating at a frequency higher than the 2.4 GHz band and the higher mode 5.2 GHz band in the above example, resonating at a lower frequency band in a direction to shorten the effective length of the first linear element 11. May be moved in a direction to increase the effective length. The 2.4 GHz band is set as the first resonance frequency because the same frequency is currently used for wireless LANs and the like, and other frequencies (for example, 2.0 GHz and 5.0 GHz) are used as necessary. It does not prevent setting.
[0022]
(Structure of linear conductor)
The linear conductor will be described with reference to FIGS. The linear conductor 25 provided on the antenna forming surface 9 is a conductor for achieving impedance matching at the feed terminal 19 which is a feed point. The linear conductor 25 is branched on the antenna forming surface from a branch point 23 near the first linear element base end 12, and its distal end is connected to the ground terminal 21 provided on the end surface of the dielectric substrate 7. It is connected via a bent portion 27. Although the linear conductor 25 can be formed in a separate process from the first linear element 11, it is more convenient to print and form the linear conductor 25 simultaneously with the first linear element 11 using a conductive paste. The feed point impedance can be adjusted by shifting the position of the branch point 23 in the length direction of the first linear element 11. Furthermore, since the linear conductor 25 is also a part that contributes to the resonance of the first linear element 11, the resonance frequency of the first linear element 11 can be adjusted by adjusting its length. It is convenient to form the ground terminal 21 by applying a conductive paste to the end of the dielectric substrate 7 as in the case of the power supply terminal 19.
[0023]
A dummy electrode (not shown) for securely soldering the dielectric antenna 1 to a parent substrate (not shown) or the like is provided on the back surface of the lower substrate 5 (the surface on the back side of the paper of FIG. 2). . When mounted on a parent board (not shown), the power supply terminal 19 is connected to the power supply section P of the parent board, and the ground terminal 21 is connected to the ground section G by soldering.
[0024]
(Configuration of second linear element)
As shown in FIGS. 1 to 3, a linear (band-shaped) second linear element 31 is formed on the antenna forming surface 9. The second linear element 31 is branched from the first linear element 11 via a branch 33, and has a step 35 in the middle thereof. The step 35 is provided mainly for separating the open end 37 of the second linear element 31 from the linear conductor 25 so as to make it less affected by the effect. The second linear element 31 is conveniently formed by printing a conductive paste together with the first linear element 11.
[0025]
Here, the high-frequency current supplied from the power supply unit P flows from the base end 12 of the first linear element 11 to the first bent portion k1, the second bent portion k2, the third bent portion k3, and the open end 17. Flow in order. On the other hand, the high-frequency current flowing through the second linear element 31 passes through the branch portion 33 from the base end portion 12 and flows through the step portion 35 to the open end 37 thereof. The second linear element 31 is set to have a length (for example, 波長 wavelength) capable of resonating at a third resonance frequency different from both the first resonance frequency and the second resonance frequency. Adjustment of the resonance frequency of the second linear element 31 is performed by moving the position of the branch portion 33 on the first linear element 11 in its length direction. As the length from the base end portion 12 to the branch portion 33 is increased, the substantial length of the second linear element 31 is increased, so that the resonance frequency is lowered. The frequency increases.
[0026]
The relationship between the first resonance frequency, the third resonance frequency, and the second resonance frequency is determined according to the purpose of use of the dielectric antenna 1. That is, as shown in FIG. 4A, by bringing the third resonance frequency F3 of the first linear element 11 and the resonance frequency F2 of the second linear element 31 close to each other, for example, the band F equal to or lower than VSWR2 is obtained. If it is set so that it can be obtained, the provision of the second linear element 31 can widen the frequency band of the entire dielectric antenna 1 into two bands and widen a high frequency band. Also, as shown in FIG. 4B, the dielectric antenna 1 is resonated at three frequencies by separating the second resonance frequency F2 and the third resonance frequency F3 appropriately, that is, a tri-band is formed. be able to. In the present embodiment, for example, when the first resonance frequency F1 is set in the 2.4 GHz band and the second resonance frequency F2, which is a higher mode thereof, is set in the 5.2 GHz band, the third resonance frequency is set to 5.25 GHz. The band was set to 8 MHz. These frequency bands are set because these frequency bands are used for wireless LANs in Japan. It does not prevent setting to a frequency band other than the above for other usage purposes.
[0027]
The dielectric antenna 1 described so far can be suitably used by being incorporated in various mobile communication devices. As the mobile communication device, for example, there are a mobile phone, an amateur / business radio communication device, and a small computer 101 as shown in FIG.
[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the dielectric antenna which concerns on this invention, while being able to resonate at at least three resonance frequencies, the dielectric antenna which aimed at miniaturization can be provided. Therefore, according to the mobile communication device incorporating such a dielectric antenna, the size of the mobile communication device itself can be reduced, and comfortable mobile communication can be performed through transmission and reception of good radio waves.
[Brief description of the drawings]
FIG. 1 is a perspective view of a dielectric antenna according to an embodiment.
FIG. 2 is an exploded perspective view of the dielectric antenna shown in FIG.
FIG. 3 is a plan view in which an upper substrate of the dielectric antenna shown in FIG. 1 is omitted.
FIG. 4 is a table showing frequency characteristics.
FIG. 5 is a front view of a small computer as an example of a mobile communication device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dielectric antenna 3 Upper substrate 5 Lower substrate 7 Dielectric substrate 9 Antenna formation surface 9a, 9b, 9c, 9d Outer periphery 11 First linear element 12 Base end 13 First part 14 Third part 15 Second part 16 4 parts 17, 37 open end 19 power supply terminal 21 ground terminal 23 branch point 25 linear conductor 31 second linear element 33 branch 35 step 101 small computer (mobile communication device)
k1 first bent portion k2 second bent portion k3 third bent portion G ground portion P power feeding portion

Claims (4)

A dielectric substrate having a rectangular antenna forming surface;
A first linear element extending on the antenna forming surface adjacent to the outer periphery of the antenna forming surface and capable of resonating at a first resonance frequency and a second resonance frequency corresponding to a higher mode of the first resonance frequency;
A power supply terminal connected to the first linear element base end,
A linear conductor that branches on the antenna forming surface from near the base end of the first linear element;
A ground terminal connected to the end of the linear conductor,
A second linear element that branches off from the first linear element via a branch portion and is located in an internal region of the antenna forming surface on the antenna forming surface;
A dielectric antenna, wherein the second linear element is configured to resonate at a third resonance frequency other than the first resonance frequency or the second resonance frequency. The first linear element has a first bent portion, a second bent portion, and a third bent portion located between a base end and an open end,
That the outward part located between the first bent part and the second bent part and the return part located between the third bent part and the open end are arranged substantially in parallel. The dielectric antenna according to claim 1, wherein: The dielectric antenna according to claim 2, wherein a detour portion is provided in the outward path portion so as to be depressed in a direction toward an internal region of the antenna forming surface. A mobile communication device incorporating the dielectric antenna according to claim 1.

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