JPH09247025A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system in which an impedance matching circuit part provided on a mounting substrate is eliminated and whose manufacture cost can be reduced and whose manufacture period can be shortened. SOLUTION: The antenna device 10 is composed of an antenna main body 11 and the impedance matching circuit part 12. The antenna main body 11 has a conductor 14 which is spirally wound in the substrate 13 of a rectangular parallelopiped whose main components are barium oxide, aluminum oxide silica in the longitudinal direction of the substrate 13 and a feed terminal 15 for applying voltage to the conductor 14 on the surface of the substrate 13. The impedance matching circuit part 12 has an inductance element 16 formed in the substrate 13 shared with the antenna main body 11 and a capacitance element 17. The capacitance element 17 has a capacitor electrode 18 provided in the substrate 13 and a ground electrode 19 provided at the back of the substrate 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device, and more particularly to an antenna device used for a mobile communication device for mobile communication and a local area network (LAN).

[0002]

2. Description of the Related Art FIG. 15 is a perspective view of a conventional antenna device 50. Reference numeral 51 is an antenna main body, 52 is a mounting board for mounting the antenna main body 51, 53 is a ground pattern formed on the mounting board 52, and 54 is the same mounting board 52.
It is the transmission line formed above. The ground pattern 53 is connected to the ground. The transmission line 54 is connected to the power supply V, and the power supply V is connected to the ground.
At this time, the transmission line 54 is designed to have a characteristic impedance of 50Ω.

As shown in FIG. 16, the antenna body 51 has a rectangular parallelepiped insulator 55 in which an insulator layer (not shown) made of an insulator powder such as alumina or steatite is laminated.
And a conductor 56 made of silver, silver-palladium or the like and formed in a coil inside the insulator 55, and a magnetic powder such as ferrite powder, and formed inside the insulator 55 and the coil-shaped conductor 56. And the external connection terminals 58a and 58b that are adhered and baked on the lead-out end (not shown) of the conductor 56 after firing the insulator 55. That is, the antenna body 51 has a structure in which the coil-shaped conductor 56 is wound around the magnetic body 57 and sealed with the insulator 55.

[0004]

However, in the above-described conventional antenna device, when the input impedance of the antenna body and the characteristic impedance of the transmission line are different, it is mounted between the external terminal of the antenna body and the transmission line, that is, mounted. It is necessary to provide an impedance matching circuit including an inductance element and a capacitance element on the substrate.

However, since the inductance element and the capacitance element are chip parts, the occupied area and the occupied volume of the impedance matching circuit on the mounting board are large, and the antenna device is large, and further,
There is a problem that a mobile communication device or the like equipped with the antenna device becomes large in size.

Further, since it is necessary to separately manufacture the antenna main body and the impedance matching circuit and mount them on the mounting board, there are problems that the manufacturing cost becomes high and the manufacturing period becomes long.

The present invention has been made in order to solve such a problem, and an impedance matching circuit provided on a mounting substrate is not required, and the manufacturing cost and the manufacturing period can be shortened. The purpose is to provide a device.

[0008]

In order to solve the above problems, the present invention provides a substrate made of at least one of a dielectric material and a magnetic material, and at least one formed on the surface and / or the inside of the substrate. A conductor; and an antenna main body that is formed on the surface of the base and includes at least one power supply terminal for applying a voltage to the conductor,
It is characterized by comprising at least one induction element and at least one capacitance element formed on at least one of the surface and the inside of the base of the antenna body.

According to the antenna device of the present invention, the input impedance of the antenna device can be adjusted by providing the inductance element and the capacitance element on at least one of the surface and the inside of the base of the antenna body.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a perspective view and a side view of a first embodiment of an antenna device according to the present invention.

The antenna device 10 comprises an antenna body 11 and an impedance matching circuit section 12, and the antenna body 1
1 includes a conductor 14 that is spirally wound in the longitudinal direction of the base body 13 inside a rectangular parallelepiped base body 13 mainly containing barium oxide, aluminum oxide, and silica.

On the other hand, the impedance matching circuit section 12 is
A power supply terminal 15 for applying a voltage to the conductor 14 is provided on the surface of the base 13 shared with the antenna body 11, and an inductive element 16 and a capacitance element 17 are provided inside the base 13. At this time, the capacitance element 1
7 is a capacitor electrode 18 provided inside the base 13.
And the ground electrode 19 provided on the side surface and the back surface of the base body 13.
Is formed.

One end of the conductor 14 of the antenna body 11 and one end of the inductance element 16 are connected to the capacitor electrode 18. In addition, the conductor 14 of the antenna body 11
The other end of the inductance element 16 forms a free end 21 inside the base body 13, and the other end of the inductance element 16 is led out to the side surface of the base body 13 to form a power feeding portion 22. Further, the power feeding portion 22 is provided in the base 13 for applying a voltage to the conductor 14.
Is connected to the power supply terminal 15 formed on the surface.

The power supply terminal 15 is connected to the power supply V, and the power supply V is connected to the ground. Further, the ground electrode 19 is connected to the ground.

The equivalent circuit of the antenna device 10 at this time is as shown in FIG. That is, the inductance element 16 is connected in series and the capacitance element 17 is connected in parallel to the conductor 14 of the antenna body 11.
The capacitance element 17 is connected between the connection point of the conductor 14 and the inductance element 16 and the ground.

4 and 5 are a perspective view and a side view of a second embodiment of the antenna device according to the present invention. In the second embodiment, the same or equivalent parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

This antenna device 20 is different from the antenna device 10 of the first embodiment in that one end of the conductor 14 of the antenna body 11 is connected to one end of the inductance element 16 and the other end of the inductance element 16 is a capacitor electrode. 1
It differs in that it is connected to 8.

The equivalent circuit of the antenna device 20 at this time is as shown in FIG. That is, similarly to the first embodiment, the inductance element 16 and the capacitance element 17 are connected in series or in parallel to the conductor 14 of the antenna body 11. However, unlike the first embodiment, the capacitance element 17 is connected between the connection point of the inductance element 16 and the power supply V and the ground.

7 to 10 show insertion loss characteristics of the antenna device, and FIGS. 11 to 14 show input impedance characteristics of the antenna device. Among them, FIGS. 7, 9, 11 and 13 show the case of the antenna device without the impedance matching circuit section, and FIGS. 8 and 12 show the inductance element having the inductance value of 56 nH and the capacitance value of 4 pF. Antenna device 10 in which the capacitance elements are provided in series or in parallel with conductors
10 and 14 show the case of the antenna device 20 in which the inductance element having the inductance value of 3 nH and the capacitance element having the capacitance value of 4 pF are respectively provided in series or in parallel with the conductor.

From the results of the insertion loss characteristics of the antenna device shown in FIGS. 7 to 10, the insertion loss can be reduced by providing the impedance matching circuit section including the inductance element and the capacitance element inside the base body shared with the antenna body. It can be understood that the insertion loss characteristic is improved.

Next, in Table 1, the reflection coefficient at the resonance frequency of the antenna body obtained from FIGS. 7 to 10 and the resonance frequency of the antenna device obtained from FIGS. 11 to 14 (arrow 1 in the figure) | Indicates Γ |. At this time, the reflection coefficient | Γ |
Is represented by | (Zin−Zo) / (Zin + Zo) |, where Zin is the input impedance of the antenna body, Zo
Is the characteristic impedance of the transmission line.

[0022]

[Table 1]

From the results shown in Table 1, by providing the impedance matching circuit section including the inductance element and the capacitance element inside the base body shared with the antenna body, the conventional impedance matching circuit section is provided on the mounting board together with the antenna body. As in the case, the reflection coefficient | Γ
| Is brought close to zero, that is, the input impedance of the antenna main body is the characteristic impedance of the transmission line
It is understood that it is possible to match with Ω.

For example, when the input impedance of the antenna body is larger than the characteristic impedance of the transmission line, a capacitance element may be provided between the connection point of the conductor and the inductance element and the ground, as shown in FIG. If the input impedance of the antenna body is smaller than the characteristic impedance of the transmission line, a capacitance element may be provided between the connection point between the inductance element and the power supply and the ground, as shown in FIG.

In the above-mentioned antenna device, the base of the antenna body is made of barium oxide, aluminum oxide,
Although the case where the substrate is made of a dielectric material containing silica as a main component has been described, the base material is not limited to this dielectric material, and titanium oxide, a dielectric material containing neodymium oxide as a main component, nickel, cobalt, iron. May be composed of a magnetic material containing as a main component, or may be composed of a combination of a dielectric material and a magnetic material.

The case where the conductor of the antenna body is spirally wound in the longitudinal direction of the base has been described.
It may be wound in the height direction of the substrate.

Further, the case where the shape of the winding cross section orthogonal to the winding axis C of the conductor of the antenna body spirally wound is substantially rectangular has been described, but the shape of the winding cross section is at least partially linear. It only has to have a part. In this case, since the main polarization and the cross polarization from the winding axis direction and the direction perpendicular to the winding axis are sensitive, an omnidirectional antenna body can be obtained.

Further, although the case where the conductor of the antenna body is spirally wound has been described, it may be formed in a meandering shape.

Further, although the case where the conductor of the antenna body is provided inside the base of the antenna device has been described, the conductor may be provided on the surface of the base of the antenna body or on both the surface and the inside.

Further, although the case where the antenna body has one conductor has been described, two or more conductors may be formed. In that case, the antenna device can have a plurality of resonance frequencies.

Further, although the case where the base of the antenna device has a rectangular parallelepiped shape has been described, it may have another shape such as a cube, a cylinder, a pyramid, a cone, and a sphere.

Further, although the case where the inductance element and the capacitance element of the impedance matching circuit section are provided inside the base of the antenna device has been described, they may be provided on the surface of the base of the antenna device or both on the surface and inside. Good. At this time, as an example of providing the capacitance element on the surface of the base, there is one formed between the capacitor electrode and the ground electrode formed side by side on one surface of the base.

[0033]

According to the antenna device of the present invention, by providing the inductance element and the capacitance element on at least one of the surface and the inside of the base of the antenna body, the input impedance at the resonance frequency is adjusted as in the conventional case. That is, the input impedance can be matched with the impedance of the transmission line. Also,
The antenna device can be downsized.

Further, since the inductance element and the capacitance element can be formed at the same time as the antenna body, the manufacturing cost and the manufacturing period can be shortened.

[Brief description of drawings]

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

FIG. 2 is a side view of the antenna device of FIG.

FIG. 3 is an equivalent circuit diagram of the antenna device of FIG.

FIG. 4 is a perspective view of a second embodiment according to the antenna device of the present invention.

5 is a side view of the antenna device of FIG. 4. FIG.

6 is an equivalent circuit diagram of the antenna device of FIG.

FIG. 7 is a reflection loss characteristic of the antenna device when the impedance matching circuit section is not provided.

FIG. 8 is a reflection loss characteristic of the antenna device when an impedance matching circuit section is provided. (Inductance value of the inductance element: 56 nH, capacitance value of the capacitance element: 4 pF)

FIG. 9 is a reflection loss characteristic of the antenna device when the impedance matching circuit is not provided.

FIG. 10 is a reflection loss characteristic of the antenna device when an impedance matching circuit is provided. (Inductance value of the inductance element: 3 nH, capacitance value of the capacitance element: 4 pF)

FIG. 11 is an input impedance characteristic of the antenna device when an impedance matching circuit is provided.

FIG. 12 is an input impedance characteristic of the antenna device when an impedance matching circuit is provided. (Inductance value of the inductance element: 56 nH, capacitance value of the capacitance element: 4 pF)

FIG. 13 is an input impedance characteristic of the antenna device when an impedance matching circuit is provided.

FIG. 14 is an input impedance characteristic of the antenna device when an impedance matching circuit is provided. (Inductance value of the inductance element: 3 nH, capacitance value of the capacitance element: 4 pF)

FIG. 15 is a perspective view of a conventional antenna device.

16 is a side view of an antenna body forming the antenna device of FIG.

[Explanation of symbols]

 10, 20 Antenna device 11 Antenna main body 13 Base 14 Conductor 15 Feeding terminal 16 Inductance element 17 Capacitance element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruhisa Tsuru 2 26-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd. Murata Manufacturing

Claims (1)

[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 surface and the inside of the substrate, and a voltage formed on the surface of the substrate. An antenna body having at least one feeding terminal for applying a voltage; and at least one induction element and at least one capacitance element formed on at least one of the surface and the inside of the base of the antenna body. Characteristic antenna device.