JPH11122024A - Laminated chip antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated chip antenna, capable of suppressing the level of radio signals to be transmitted so as not to affect human bodies and easily providing suitable directivity. SOLUTION: This antenna is provided with a base body 20 which is composed of plural kinds of materials with different dielectric constants or magnetic permeabilities and an antenna conductor 3. A part or the entire surface of the at least the back surface side of the base body 20 is constituted of a layer 2 composed of a high dielectric constant material or a high magnetic permeability material. The other part of the base body 20 is turned into a low dielectric constant material layer 1 to be put on a high dielectric constant material layer 2 or a low magnetic permeability material layer to be put on a high magnetic permeability material layer. The antenna conductor 3 is formed on at least one from among the inside, surface, and the boundary surface 13 with the high dielectric constant material layer 2 or the high magnetic permeability material layer of the low dielectric constant material layer 1 or of low magnetic permeability material layer. On the outer surface of the base body 20, a power feeding terminal 5 connected to a part of the antenna conductor 3 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer chip antenna used for a mobile communication such as a portable telephone and a car telephone, and a local area network for performing communication between personal computers by radio.

[0002]

2. Description of the Related Art As a conventional laminated chip antenna, for example, Japanese Unexamined Patent Publication No. 9-51221 discloses, as shown in FIG. 8A, the inside of a base 20A made of a dielectric or magnetic material of one kind of material. There is a structure in which the conductor 3 is arranged in the
The conductor 3 includes an upper layer portion 3a and a lower layer portion 3b formed by forming a conductor pattern on a laminated surface, and a portion formed as a via hole 3c.

A feed point 6 which is one end of the antenna conductor 3 is exposed at an end of a base (laminated body) 20A and connected to a feed terminal 5.

[0004] This laminated chip antenna is obtained by miniaturizing an antenna 12 using an antenna as shown in FIG. 8B by shortening the wavelength obtained by using a base 20A having a dielectric constant larger than that of air. Although the characteristics such as the bandwidth and the gain vary depending on the shape, the conductor, and the conductor material, the basic characteristics are almost the same as those of the antenna, and are omnidirectional as shown by the dashed line 7 in FIG.

[0005]

It is ideal that a conventional antenna for a wireless device is omnidirectional, but if it is omnidirectional, it is used close to a human body, such as a mobile phone. In the case of an antenna of a wireless device, the influence on the human body such as a non-thermal effect due to radio wave radiation (a change in the function and behavior of a living body is recognized) and a malfunction of a cardiac pacemaker has become a problem. In particular, in recent years, the frequency band used has been increasing, and the frequency of use has become extremely high due to the spread of mobile phones and the like. Conventional linear antennas and chip antennas have a problem that such radio wave radiation has a large effect on the human body.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention can suppress the level of a radio signal to be transmitted to such an extent that it does not affect the human body, and can easily obtain a suitable directivity. The purpose is to provide.

[0007]

A laminated chip antenna according to the present invention is a laminated chip antenna comprising a base made of a plurality of kinds of materials having different dielectric constants or magnetic permeability and an antenna conductor, and at least a back surface of the base. A low dielectric constant material layer or a high magnetic permeability material layer in which a part or the whole of the side is constituted by a layer made of a high dielectric constant material or a high magnetic permeability material, and another part of the base is overlapped with the high dielectric constant material layer. A low-permeability material layer to be superimposed on at least one of the inside and the surface of the low-permittivity material layer or the low-permeability material layer, or a boundary surface with the high-permittivity material layer or the high-permeability material layer. Wherein the antenna conductor is formed, and a power supply terminal connected to a part of the antenna conductor is provided on an outer surface of the base (claim 1).

Further, the laminated chip antenna of the present invention has a rectangular parallelepiped shape, and the boundary surface is gradually approached to the front side from the line passing through the center of the back surface of the base or substantially the center in the vertical and horizontal directions to the outer peripheral side. (Claim 2).

In the present invention, the base is made of ceramics or resin or a composite material of ceramics and resin. The substrate is manufactured by a lamination method such as a screen printing method or a method of stacking green sheets.

The material of the substrate of the present invention is preferably tan δ <0.01, Q> 10 at 1 GHz.
The ceramic used as the low dielectric constant material is 0, preferably cordierite, forsterite, alumina, or a glass-based ceramic in which 1 <ε <10, and the ceramic having a high dielectric constant is 20 <ε.
<200 titanium oxide ceramics or the like are used.

When a resin is used as the base material, polytetrafluoroethylene, polyimide, bismaleimide triazine, a liquid crystal polymer, or the like is used as the low dielectric constant material, whereas these resins are used as the high dielectric constant material. What mixed the said titanium oxide type ceramics etc. is used.

When a magnetic material is used as the base material, the mixture ratio of the non-magnetic ferrite and the magnetic ferrite as the low-permeability material and the high-permeability material is changed.
A material having a magnetic permeability μ of 1 <μ <5 is defined as a low magnetic permeability material.
<200 <200 is used as a high magnetic permeability material.

[0013]

According to the first aspect, since radio waves are reflected on the boundary surface, the amount of radio waves radiated to the back surface side is reduced, and directivity can be obtained.

According to the second aspect of the present invention, since the boundary surface is formed so as to be inclined with respect to the front and back surfaces over the outer periphery than the center line or the center line in the vertical and horizontal directions, the radiation amount through the back surface is further reduced. .

[0015]

FIG. 1A is a perspective view showing an embodiment of a laminated chip antenna according to the present invention, and FIG. 1B is a sectional view thereof. The laminated chip antenna of this embodiment has a rectangular parallelepiped shape, and the base 20 is composed of a low dielectric constant material layer 1 and a high dielectric constant material layer 2 provided on a part of the back surface excluding the peripheral portion. The antenna conductor 3 is built in the low dielectric constant material layer 1. The antenna conductor 3 includes an upper layer portion 3a formed by a pattern on a portion near the surface in the base 20, a lower layer portion 3b formed on a portion near the high dielectric constant material layer 2, an upper layer portion 3a and a lower layer portion. Via hole 3 for connection with 3b
and helical antenna conductors 3.

One end of the antenna conductor 3 is exposed on the end face of the base 20 to become a feed point 6 and is connected to a feed terminal 5 provided on the end face of the base 20.

FIG. 2 shows a laminated structure of this embodiment. The case where the antenna as a laminate of the present invention is manufactured by the green sheet method will be described. The high dielectric constant material layer 2 is formed in a part of the lowermost green sheet 1a including the low dielectric constant material, which has a rectangular portion. After filling, a lower layer conductive pattern 3b is printed on the green sheet 1b containing a low dielectric constant material thereon, and the green sheet 1 containing a low dielectric constant material thereon is printed.
Via holes 3c are provided in c to 1h, and an upper layer conductive pattern 3a is formed in the uppermost green sheet 1h. The uppermost green sheet 1 i is provided for forming a protective layer of the antenna conductor 3.

These green sheets 1a to 1g are piled up and pressed, and if the base material is ceramics, baked,
If it is a resin, there is no need for firing. Thereafter, the power supply terminal 5 is baked and plated on the power supply point 6 or adhered by plating to obtain a product. An antenna having such a laminated structure can also be manufactured by a screen printing method.

As described above, the base 20 is attached to the antenna conductor 3
1B and the high-permittivity material layer 2 on the back side, as shown in FIG. 1B, the reflection coefficient of the radio wave at the boundary surface 13 increases. A part of the reflected radio wave 14 is generated. For this reason, FIG.
In the directivity characteristic diagram of the chip antenna shown in FIG. 1, the propagation of radio waves to the back side can be reduced as shown by the one-dot chain line 10. For this reason, by arranging the high magnetic permeability material layer 2 on the human body side, the influence of radio waves on the human body can be reduced.

The perspective view of FIG. 4A and the cross-sectional view of FIG. 4B are examples in which the layer 2 made of the high-permeability material is provided over the entire back surface of the base 1, and according to this embodiment. For example, it is possible to obtain a directivity as shown by a broken line 11 in FIG. 3, that is, a directivity characteristic in which the radiation amount of the radio wave on the back surface is averaged as compared with the embodiments of FIGS.

FIG. 5 (A) is a perspective view showing another embodiment of the present invention, FIG. 6 (A) is a sectional view thereof, and FIG. 6 (B) is an operation explanatory view thereof. The boundary surface 13 between the dielectric material layer 1 and the high magnetic permeability material layer 2 extends from the center line passing in the longitudinal direction of the back surface of the laminate (that is, the direction of the helical core of the antenna conductor 3) to both sides (outer periphery). The substrate is formed to be inclined so as to be closer to the surface (upper surface) side of the base 1.

Such an inclined surface is, as shown in FIG.
A layer composed of a low-permittivity material layer 1-1 having a narrow width and a high-permittivity material layer 2b on both sides thereof is laminated on the lowermost high-permittivity material layer 2a. A layer composed of a low dielectric constant material layer 1-2 slightly wider than the layer 1-1 and a high dielectric constant material layer 2c on both sides thereof is laminated, and a wide low dielectric constant material layer 1-3 and a high dielectric constant layer on both sides are further laminated. This can be realized by repeating the process of laminating the dielectric constant material layer 2d, and further laminating the wide low dielectric constant material layer 1-4 and the high dielectric constant material layers 2e on both sides thereof.

As described above, by inclining the boundary surface 13 so as to gradually rise toward the both sides from the center, as shown in FIG. 6B, the refraction of the radio wave 15 transmitted through the back surface space increases, As a result, as shown by the solid line 9 in the characteristic diagram of FIG. 5B, a characteristic in which the directivity is higher and the radiation to the back side is reduced as compared with the embodiments shown in FIGS. Radiation to the human body can be reduced.

In the embodiment shown in FIGS. 5 to 7, the boundary surface 13 is formed so as to gradually rise from the vertical center line on the back surface of the base 20 to both sides, but from the horizontal center line. A boundary surface inclined so as to gradually rise on both sides may be formed, or a boundary surface inclined so as to rise from the center of the back surface to the outer periphery of four sides may be formed.

Although the example in which the antenna conductor 3 is formed apart from the high dielectric constant material 2 has been described, in each of the above embodiments, the antenna conductor 3 may be provided over the boundary surface 13 or over the surface. Is also good.

In each of the above embodiments, even if the high dielectric material 2 is replaced with a high magnetic permeability material and the low dielectric material 1 is replaced with a low magnetic permeability material, the same reflection as described above can be produced. Directivity can be obtained. Further, the low-permittivity material or the low-permeability material may be made of a plurality of different materials.

[0027]

According to the first aspect of the present invention, the high dielectric material or the high magnetic permeability material is disposed on the back surface of the base, and the portion containing the antenna conductor is made of the low dielectric material or the low magnetic permeability material. In addition, the radiation of radio waves to the back side can be reduced, and the influence of radio wave radiation on the human body can be reduced by making the back side the human body side. Further, by selecting a combination of the permittivity and the magnetic permeability and the shape of the boundary surface, it is possible to change the mode of reflection of the radio wave, and it is possible to easily set the directional characteristics according to the purpose.

According to the second aspect, since the boundary surface is inclined, radiation to the human body can be further reduced.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an embodiment of a laminated chip antenna according to the present invention, and FIG. 1B is a sectional view thereof.

FIG. 2 is an exploded perspective view showing a laminated structure of the embodiment of FIG.

FIG. 3 is a directional characteristic diagram of the embodiment of FIGS. 1 and 2 and the embodiment of FIG. 4;

FIG. 4A is a perspective view showing another embodiment of the laminated chip antenna according to the present invention, and FIG. 4B is a sectional view thereof.

FIG. 5A is a perspective view showing another embodiment of the multilayer chip antenna according to the present invention, and FIG. 5B is a directional characteristic diagram thereof.

6A is a sectional view of the multilayer chip antenna of the embodiment of FIG. 5A, and FIG.

FIG. 7 is an exploded view showing a laminated structure of the embodiment of FIGS. 5 and 6;

FIG. 8A is a perspective view showing a conventional laminated chip antenna, and FIG. 8B is a side view showing a conventional helical wound antenna.

[Explanation of symbols]

1: Low dielectric constant material layer, 2: High dielectric constant material layer, 3: Antenna conductor, 3a, 3b: Conductor pattern, 3c: Via hole, 5: Feed terminal, 6: Feed point, 7: Directivity characteristics of conventional product, 9: directional characteristic of the embodiment of FIG. 5A, 10: directional characteristic of the embodiment of FIG. 1, 11: directional characteristic of the embodiment of FIG.
3: Boundary surface, 14: reflected radio wave, 15: transmitted radio wave, 20:
Substrate

Claims (2)

[Claims] 1. A laminated chip antenna comprising a base made of a plurality of kinds of materials having different dielectric constants or magnetic permeability and an antenna conductor, wherein at least a part or the whole of the back side of the base is made of a high dielectric material. Or a low-permittivity material layer formed of a layer made of a high-permeability material, and the other portion of the base is formed of a low-permittivity material layer overlaid on the high-permittivity material layer, or a low-permeability material layer overlaid on the high-permeability material layer. Forming the antenna conductor on at least one of the inside, the surface, or the interface with the high-permittivity material layer or the high-permeability material layer of the low-permeability material layer or the low-permeability material layer; A multilayer chip antenna, wherein a feed terminal connected to a part of the antenna conductor is provided on an outer surface. 2. The multilayer chip antenna according to claim 1, wherein the laminated chip antenna has a rectangular parallelepiped shape, and the boundary surface is gradually shifted to a front surface side from a line passing through a central portion of the back surface of the base or a substantially central portion of the vertical and horizontal directions. A multilayer chip antenna characterized by being inclined so as to be close to each other.