JPH1093320A - Chip antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the chip antenna whose antenna characteristic is almost kept constant without being affected by ground. SOLUTION: The antenna 10 is provided with a conductor 13 that is made of a copper and a copper alloy, formed by printing, vapordeposition, adhesion or plating, wound in spiral in the lengthwise direction of a rectangular prism shaped base 11 and has a capacitance forming part 12 at its one position of the base 11 in the inside of the rectangular prism shaped base 11 made of a dielectric material (specific dielectric constant : about 6.1) whose major components are barium oxide, aluminium oxide and silica. Then open ends 13a, 13b of the conductor 13 forming the capacitance forming part 12 are connected to plate parts 12a, 12b arranged in parallel in the inside of the base 11. In this case, a capacitance is formed between the plate parts 12a, 12b arranged in the inside of the base 11 in parallel. Moreover, one terminal of the conductor 13 is connected to a feeding terminal 18 provided to the surface of the base 11 to apply a voltage to the conductor 13. Furthermore, the other terminal of the conductor 13 forms a free end in the interior the base 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chip antenna used for mobile communication, a local area network (LAN), and the like.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional mobile communication device, for example, a portable telephone 30, has a non-directional whip antenna 31 protrudingly attached to an upper portion of a portable telephone main body 32, and a radio wave is transmitted from the whip antenna 31. Is sending and receiving.

[0003]

However, in the above-described conventional whip antenna, since the person holding the mobile phone is at the ground potential, the user is affected by the ground when using the mobile phone and holds the mobile phone. There has been a problem that antenna characteristics such as directional characteristics fluctuate due to the movement of a person.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a chip antenna capable of keeping antenna characteristics almost constant without being greatly affected by ground. Aim.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a substrate comprising at least one of a dielectric material and a magnetic material, and at least one substrate formed on at least one of the inside and the surface of the substrate. It is characterized by comprising a conductor, and at least one power supply terminal provided on the surface of the base for applying a voltage to the conductor, wherein the conductor is provided with at least one capacitance forming portion.

[0006] Further, a plate-like portion arranged in parallel with each other is connected to each open end of the conductor constituting the capacitance forming portion.

According to the chip antenna of the present invention, since the conductor has at least one capacitance forming portion, a change in capacitance generated between the conductor of the chip antenna and the ground is reflected in a change in resonance frequency. It becomes difficult.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a chip antenna according to the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a perspective perspective view and an exploded perspective view of a first embodiment of a chip antenna according to the present invention. The chip antenna 10 has a rectangular parallelepiped base 11 having a mounting surface 111, and a spiral wound inside the base 11 in a direction in which the winding axis C is parallel to the mounting surface 111, that is, in a longitudinal direction of the base 11. And a conductor 13 having a capacitance forming portion 12 in one place. At this time, the open ends 13a and 13b of the conductor 13 forming the capacitance forming portion 12 are connected to the plate portions 12a and 12b, respectively, inside the base 11.

Here, the rectangular parallelepiped substrate 11 in which the conductor 13 is spirally wound has rectangular sheet layers 11a to 11c made of a dielectric material mainly containing barium oxide, aluminum oxide and silica. Laminated.

Among these, on the surfaces of the sheet layers 11b and 11c, rectangular plate-like portions 12a and 12b made of copper or a copper alloy, and linear or substantially L-shaped conductive patterns 14a to 14h are provided. But printing, vapor deposition,
In addition to being provided by bonding or plating, the sheet layer 11b is provided with a via hole 15 formed in the thickness direction.

By stacking the sheet layers 11a to 11c and connecting the conductive patterns 14b to 14h with the via holes 15, the winding section has a rectangular shape and is spirally wound. Conductor 13 having
Is formed. At this time, one end of the conductive pattern 14a (one open end 13a of the conductor 13) is connected to one end of the conductive pattern 14e (one open end 13a of the conductor 13).
b) is connected to each of the plate portions 12b. Further, a capacitance is formed between the plate-like portions 12a and 12b provided inside the base 11 and arranged so as to be parallel to each other.

The other end of the conductive pattern 14a (the conductor 1
3) is drawn out to the surface of the base body 11 and
Is formed, and is connected to a power supply terminal 17 provided on the surface of the base 11 in order to apply a voltage to the conductor 13. Further, one end of the conductive pattern 14h (the other end of the conductor 13)
A free end 18 is formed inside the base 11.

FIGS. 3 and 4 show the chip antenna 1 of FIG.
0 shows a perspective view of a modification of FIG. 3 includes a conductor 1 wound spirally along the surface of a rectangular parallelepiped base 111 and having a capacitance forming portion 121 in one place.
31. The open ends 131a and 131b of the conductor 131 forming the capacitance forming portion 121 are connected to the base 11
1 and connected inside the base 111 to plate-like portions 121a and 121b arranged in parallel with each other. At this time, the plate-like portions 121a and 121b provided inside the base body 111 and arranged so as to be parallel to each other are provided.
Between, a capacitance is formed. Note that one end of the conductor 131 is
On the surface of the base 111, it is connected to a power supply terminal 171 provided on the surface of the base 111 to apply a voltage to the conductor 131. The other end of the conductor 131 forms a free end 181 inside the base 111. In this case,
Since the conductor can be easily formed spirally on the surface of the base by screen printing or the like, the manufacturing process of the antenna body can be simplified.

The chip antenna 102 shown in FIG. 4 includes a conductor 132 formed in a meandering shape on the surface of a rectangular parallelepiped base 112 and having a capacitance forming portion 122 in one place. The open ends 132a and 132b of the conductor 132 forming the capacitance forming section 122 are provided inside the base 112 and are arranged in parallel with each other.
a and 122b are connected inside the base 112. At this time, a capacitance is formed between the plate portions 122a and 122b provided inside the base 112 and arranged so as to be parallel to each other. Note that one end of the conductor 132 is connected to the surface of the base 112 to apply a voltage to the conductor 132 on the surface of the base 112.
2 is connected to the power supply terminal 172 provided on the surface of the second power supply 2.
The other end of the conductor 132 forms a free end 182 on the surface of the base 112. In this case, since the meandering conductor is formed only on one main surface of the base, the base can be made thinner, and accordingly, the height of the chip antenna can be reduced. The meandering conductor may be formed inside the base.

Next, as shown in FIG. 5, the chip antenna 10 is connected to the reference ground electrode 19a and the side ground electrode 19a.
b was mounted on the mounting substrate 20 provided on the surface, and the resonance frequency was evaluated while changing the interval A (mm) between the chip antenna 10 and the side ground electrode 19b. Table 1 shows the results.

The distance between the chip antenna 10 and the reference ground electrode 19a is fixed at 3 (mm). Also,
As shown in FIG. 6, the shape of the plate-like portions 12a and 12b is determined by using the values of X and Y shown in Table 1 to obtain X (mm) × Y (m
m), and the interval between the plate-like portions 12a and 12b is 0.1 (m
m) It is constant.

[0018]

[Table 1]

From these results, the X of the plate-like portions 12a, 12b
It is understood that the variation of the resonance frequency due to the approach of the side-surface ground electrode 19b is smaller in each sample of the present embodiment where Y and Y (FIG. 6) are changed than in the monitor without the capacitance forming section 12. . That is, the present embodiment indicates that the resonance frequency can be kept substantially constant without being significantly affected by the side surface ground electrode 19b.

The reason will be described below. The resonance of an antenna having no capacitance forming part such as a monitor can be considered as a series resonance of the inductance L of the spiral conductor and the capacitance C generated between the conductor and the ground. f1 = 4π / SQR (LC) (1) The fact that the ground approaches the antenna means that the stray capacitance generated between the conductor and the ground increases, and that the capacitance C in the above equation (1) increases. Therefore, the movement of the ground causes a change in antenna characteristics.

On the other hand, in the chip antenna 10 according to the embodiment of the present invention, by providing the capacitance forming section 12, the capacitance C1 generated in the capacitance forming section 12 is reduced by the capacitance C1 generated between the conductor and the ground. , The resonance frequency of the chip antenna 10 is given by f2 = 4π / SQR (LCCC1 / (C + C1)) (2)

Here, assuming that the capacitance C generated between the conductor and the ground has changed by ΔC, comparing only the route (SQR) of the above-described equations (2) and (1),
Since / C1> 0, (ΔC · C1 / (ΔC + C1)) − ΔC = ΔC ((1 / (1 + ΔC / C1)) − 1) <0 (3) It will be understood that they are smaller.

This is because the resonance frequency f2 of the chip antenna 10 according to the embodiment of the present invention is less susceptible to the change ΔC of the capacitance C generated between the conductor and the ground. This shows that the antenna characteristics (resonance frequency) can be kept constant without receiving much.

As described above, in the first embodiment, since the conductor of the chip antenna has one capacitance forming portion,
The capacitance generated in the capacitance forming portion is connected in series with the capacitance generated between the conductor and the ground, and the antenna characteristics can be kept almost constant without being greatly affected by the ground.

In addition, since the open ends of the conductor forming the capacitance forming portion are provided with plate portions arranged so as to be parallel to each other, the shape of the plate portion is controlled so that the capacitance forming portion is formed. The capacity generated in the unit can be controlled. Therefore, the antenna characteristics can be kept more constant.

FIG. 7 is a perspective view of a chip antenna according to a second embodiment of the present invention. Chip antenna 20
1 is different from the chip antenna 10 of FIG. 1 in that a plate-like portion constituting a capacitance forming portion is provided on the surface of a base.

That is, the chip antenna 20 is a rectangular parallelepiped base 2 made of a dielectric material (relative permittivity: about 6.1) containing barium oxide, aluminum oxide, and silica as main components.
1, spirally wound in the longitudinal direction of the base 21,
A conductor 23 having a capacitance forming portion 22 in one place is provided. The open ends 23a and 23b of the conductor 23 forming the capacitance forming portion 22 are provided on the surface of the base 21 and connected to plate-like portions 22a and 22b arranged to be parallel to each other. At this time, a capacitance is formed between the plate-shaped portions 22a and 22b provided inside the base 21 and arranged so as to be parallel to each other.

One end of the conductor 23 is drawn out to the surface of the base 21, and is applied to the conductor 23 to apply a voltage to the conductor 23.
1 is connected to a power supply terminal 27 provided on the surface of the power supply terminal 1. The other end of the conductor 23 forms a free end 28 inside the base 21.

As described above, in the second embodiment, since the plate-like portions arranged so as to be parallel to each other are provided on the surface of the base, in addition to the effects of the first embodiment, the base is made thin. can do. Therefore, the height of the chip antenna can be reduced.

In the first and second embodiments,
The case where the base is made of a dielectric material containing barium oxide, aluminum oxide, and silica as main components has been described, but the base is not limited to this dielectric material, and the base contains titanium oxide and neodymium oxide as main components. A dielectric material, a magnetic material mainly containing nickel, cobalt, and iron, or a combination of a dielectric material and a magnetic material may be used.

In addition, the case where the number of conductors is one has been described, but a plurality of conductors may be provided in parallel. In this case, it is possible to have a plurality of resonance frequencies according to the number of conductors, and it is possible to cope with multiband with one antenna.

Further, the case where the conductor is formed inside or on the surface of the base has been described. However, the conductor may be formed by winding a conductor pattern on both the surface and the inside of the base.

Although the case where the conductor is provided with the capacitance forming portion in one place has been described, the capacitance forming portion may be provided in two or more places of the conductor so that they are connected in series. In this case, the capacitance C1 generated in the entire capacitance forming portion becomes smaller as the capacitance forming portion increases, so that (1− (1 / (1 + ΔC / C1))) in Expression (3) becomes larger. Become. Therefore, as the number of the capacitance forming portions increases, the capacitance C is less affected by the change ΔC of the capacitance C generated between the conductor and the ground as compared with the conventional example having no capacitance forming portion. That is, the larger the number of capacitance forming portions, the less the influence of the ground, and the more stable the antenna characteristics (resonance frequency).

[0034]

According to the chip antenna of the first aspect, since the conductor has at least one capacitance forming portion, the capacitance generated in the capacitance forming portion is smaller than the capacitance generated between the conductor and the ground. Since the antennas are connected in series, the antenna characteristics can be kept almost constant without being affected by the ground.

According to the chip antenna of the present invention, the open ends of the conductor forming the capacitance forming portion are provided with the plate portions arranged so as to be parallel to each other. , The capacitance generated in the capacitance forming unit can be controlled. Therefore, the antenna characteristics can be kept more constant.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a chip antenna according to the present invention.

FIG. 2 is an exploded perspective view of the chip antenna of FIG.

FIG. 3 is a perspective view showing a modification of the chip antenna of FIG. 1;

FIG. 4 is a perspective view showing another modification of the chip antenna of FIG. 1;

FIG. 5 is a top view showing a jig for evaluating the resonance frequency of the chip antenna of FIG. 1;

FIG. 6 is a perspective view showing a shape of a plate-shaped portion of the chip antenna of FIG. 1;

FIG. 7 is a perspective view showing a second embodiment of the chip antenna according to the present invention.

FIG. 8 is a plan view showing a mobile phone equipped with a conventional whip antenna.

[Explanation of symbols]

 10, 20 Chip antenna 11, 21 Base 12, 22 Capacitor forming portion 12a, 12b, 22a, 22b Plate portion 13, 23 Conductor 13a, 13b, 23a, 23b Open end 17, 27 Feeding terminal

Continued on the front page (72) Inventor Haruhumi Bandai 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A substrate made of at least one of a dielectric material and a magnetic material, at least one conductor formed on at least one of the inside and the surface of the substrate, and a surface of the substrate for applying a voltage to the conductor. A chip antenna, comprising: at least one power supply terminal provided in the first conductor; and at least one capacitor forming portion provided in the conductor. 2. The chip antenna according to claim 1, wherein plate-shaped portions arranged in parallel with each other are connected to each open end of said conductor forming said capacitance forming portion.