JPH0653733A - Resonator antenna - Google Patents

Abstract

PURPOSE:To obtain a resonator antenna enabling miniaturization and chip unit design by taking impedance matching without provision of a separate component. CONSTITUTION:The resonator antenna 10 has an equivalent circuit comprising an inductance L and a capacitance C1. The inductance L consists of two inductance portions L1, L2. An intermediate point of the two inductance portions L1, L2 is used for a feeding point F. Furthermore, a point between the inductance L1 and the capacitance C1 is used for a ground point E. The resonator antenna 10 is mounted on the surface of a printed circuit board having a distributed inductance component L3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonator antenna, and more particularly to a resonator antenna used for mobile communication.

[0002]

2. Description of the Related Art As a resonator antenna for mobile communication such as vehicle-mounted, a resonator antenna 1 having an equivalent circuit combining an inductance L and a capacitance C as shown in FIG. 12 is used. In such a resonator antenna 1, a feeding point F exists on the inductance side and a ground point E exists on the capacitance side.

As such a resonator antenna, for example, there is a microstrip antenna as shown in FIGS. 13 (A) and 13 (B). The microstrip antenna 2 includes a dielectric substrate 3, and patch electrodes 4 and shield electrodes 5 are formed on both surfaces of the dielectric substrate 3. And
On the shield electrode 5 side of the dielectric substrate 3, for example, a protrusion 6 for attaching a connector is formed, the inner conductor of the attached connector is connected to the patch electrode 4, and the outer conductor is connected to the shield electrode 5. It has become so.

[0004]

However, as shown in FIG.
In the resonator antenna of the circuit shown in (1), it is difficult to adjust the impedance, and it is difficult to achieve impedance matching with an external circuit. Therefore, in order to achieve impedance matching with an external circuit, it is necessary to connect the matching circuit 7 including the inductance and the capacitance as shown in FIG. 14 to the feeding point F. Therefore, it is necessary to add such a matching circuit 7 as a component different from the resonator antenna 1, and it is difficult to reduce the size.

Further, the resonator antenna having the structure shown in FIG. 13 cannot be made into a chip and cannot be surface-mounted on a printed circuit board or the like because of the protrusion 6 for mounting the connector. Further, as realized in the literature, about 1/10 wavelength is required at the longest part of the resonator antenna in order to have characteristics as an antenna, and further miniaturization is required for making into a chip. There is.

Therefore, a main object of the present invention is to provide a resonator antenna which can be impedance-matched without attaching another component and which can be miniaturized and made into a chip.

[0007]

According to the present invention, in a resonator antenna having an equivalent circuit composed of an inductance and a capacitance, the inductance is composed of two inductance parts, and a midpoint between the two inductance parts is used as a feeding point. Is a resonator antenna. The structure of the resonator antenna includes a linear or planar antenna electrode formed on one main surface of the dielectric layer and a planar shield electrode formed on the other main surface of the dielectric layer. The antenna electrode and the shield electrode are connected by an external electrode formed on the side surface of the dielectric layer, and the connection point between the antenna electrode and the shield electrode is a feeding point.

[0008]

In the equivalent circuit of the resonator antenna, the impedance of the antenna can be changed by adjusting the ratio of the inductance values of the two inductance parts. The antenna electrode and the shield electrode are connected by an external electrode formed on the side surface of the dielectric layer, and the external electrode is used as a feeding point.

[0009]

According to the present invention, impedance matching with an external circuit can be achieved by adjusting the inductance values of the two inductance portions,
There is no need to attach a matching circuit as a separate component. Therefore, the resonator antenna can be downsized.

Further, by adopting the structure of the present invention, the connection with the external circuit can be made by the external electrode, and the connector mounting protrusion and the like are not required. for that reason,
A resonator antenna can be manufactured as a small chip component that can be surface-mounted on a printed circuit board or the like.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0012]

1 is an equivalent circuit diagram of a resonator antenna of the present invention. The resonator antenna 10 includes an inductance L and a capacitance C1. The inductance L is
It consists of two inductance parts L1 and L2.
These inductance portions L1 and L2 and the capacitance C1 are connected in a loop. Then, a feeding point F is formed between the two inductance portions L1 and L2. Further, a ground point E is formed between the one inductance portion L1 and the capacitance C1. This ground point E is connected to a ground electrode such as a printed circuit board.
In FIG. 1, L3 is a distributed inductance component possessed by the printed circuit board on which the antenna 10 is mounted.

As a resonator antenna having such an equivalent circuit, for example, an antenna having the structure shown in FIGS. 2 and 3 can be considered. The resonator antenna 10 includes a block body 11. Further, the block body 11 is composed of the dielectric layer 1
Including 2. An antenna electrode 14 is formed on one main surface of the dielectric layer 12. The antenna electrode 14 is linearly formed along the peripheral edge of the dielectric layer 12, for example. In the resonator antenna 10 shown in FIG. 3, the antenna electrode 14 is formed in a shape in which a loop-shaped part is cut. Then, one end of the antenna electrode 14 is drawn out to the end of the dielectric layer 12.

A shield electrode 16 is formed on the other main surface of the dielectric layer 12. The shield electrode 16 is formed on almost the entire surface of the dielectric layer 12 except the peripheral portion of the other main surface. A plurality of ground terminals 18 are formed from the shield electrode 16 toward the opposite ends of the dielectric layer 12.
Further, the outer layer 20 is formed so as to cover the antenna electrode 14, and the outer layer 22 is formed so as to cover the shield electrode 16.
Is formed. These dielectric layer 12 and antenna electrode 1
4, the block body 11 is formed in a state where the shield electrode 16 and the outer layers 20 and 22 are laminated.

Further, on the side surface of the block body 11, a plurality of external electrodes 24a, 24b, 24c, 24d, 24e,
24f, 24g, 24h, 24i, 24j, 24k and 24l are formed. The external electrodes 24a to 24l are formed in a U-shaped cross section so as to extend from the side surface of the block body 11 to both main surfaces. These external electrodes 24a to 24l
Among them, the external electrode 24 a located at the lead-out portion of the antenna electrode 14 is connected to the lead-out portion of the antenna electrode 14 and the ground terminal 18 of the shield electrode 16. Also,
The other external electrodes 24b to 24l are shield electrodes 1
6 to the other ground terminal 18. The external electrode 24a is used as a feeding point, and the other external electrode 24b is used.
~ 24l is used for grounding.

In this resonator antenna 10, the distributed inductance component of the antenna electrode 14 forms the inductance portion L2 of the equivalent circuit, and the distributed inductance component of the shield electrode 16 forms the inductance component L1 of the equivalent circuit. Further, the distributed capacitance generated between the antenna electrode 14 and the shield electrode 16 forms the capacitance C1 of the equivalent circuit. The resonance frequency fr of the resonator antenna 10 is expressed by the following equation.

[0017]

[Equation 1]

As an example, a laminated resonator antenna having a length of 8 mm, a width of 5 mm, and a thickness of 2.5 mm was manufactured, and its directional characteristics were measured. And the result was shown in FIG. In this resonator antenna, C1 = 1.
It was 91 pF, L1 + L2 = 4.91 nH, and the resonance frequency of the resonator antenna was 1.644 GHz. Figure 4
As can be seen from the above, with this resonator antenna 10, an omnidirectional antenna could be obtained. The antenna gain was -11.0 dBi at the best.

In this resonator antenna 10, the inductance value of the inductance portion L2 can be adjusted by adjusting the width and length of the antenna electrode 14, and the inductance portion L1 can be adjusted by adjusting the area of the shield electrode 16. The inductance value of can be adjusted. Then, these inductance parts L1, L
The impedance of the resonator antenna 10 can be adjusted by adjusting the ratio of the inductance values of 2. Therefore, impedance matching with an external circuit can be achieved, and there is no need to attach a matching circuit as a separate component. Therefore, the resonator antenna 10 can be downsized.

As shown in FIG. 5, this resonator antenna 10 can be surface-mounted on a printed circuit board 30 or the like. A strip electrode 32 and a ground electrode 34, for example, are formed on one main surface of the printed circuit board 30 with a space therebetween. In this case, the strip electrode 32 is formed so as to extend from one end of the printed circuit board 30, and the ground electrode 34 is formed so as to surround the strip electrode 32. The strip electrode 32 is connected to the external electrode 24a, and the ground electrode 34 is connected to the external electrodes 24b to 24l. The strip electrode 32 and the ground electrode 34 connected to the resonator antenna 10 can be connected to other circuits via the connector 36 and the like.

Thus, the resonator antenna 10 is
It can be made into chips and can be surface-mounted on the printed circuit board 30. Moreover, with such a structure, the maximum length of the resonator antenna 10 can be set to about 1/20 wavelength, and the size can be reduced.

The shape of the antenna electrode 14 is as follows.
As shown in FIGS. 6 and 7, the width may be changed, or as shown in FIG. 8, the dielectric layer 12 may be formed in a spiral shape so as to extend from the peripheral portion to the central portion. Furthermore, as shown in FIG. 9, the antenna electrode 14 may be formed in a planar shape. In this way, the ratio of the inductance values of the inductance portion L1 and the inductance portion L2 can be adjusted by changing the width, length, area, etc. of the antenna electrode 14.

Further, as shown in FIG. 10, the dielectric layer 12
A planar stack electrode 42 may be formed by sandwiching another dielectric layer 40 between the shield electrode 16 and the shield electrode 16. In this resonator antenna 10, between the stack electrode 42 and the antenna electrode 14 and between the stack electrode 42 and the shield electrode 16
Capacitance is generated between and, and the bandwidth of the resonator antenna 10 can be increased. In the structure shown in FIG.
Resonator antenna 1 having a size of mm × 5 mm × 2.5 mm
No. 0 was manufactured, and its directional characteristics were measured and shown in FIG.
As can be seen from FIG. 11, this resonator antenna 10 can also provide an omnidirectional antenna. The antenna gain was −5.98 dBi at the best position.

As described above, according to the present invention, the resonator antenna can be a small chip component without requiring a separate component for impedance matching. Therefore, the resonator antenna can be surface-mounted on a printed circuit board or the like. The end of the antenna electrode does not necessarily have to be drawn out, but may be drawn from the middle part to the end of the dielectric layer. In this case, an external electrode serving as a feeding point is formed on a side surface different from those of the above-described respective embodiments.
In addition, if a resonator antenna having such a laminated structure is used,
Not only the resonator antenna of the circuit shown in FIG. 1 but also a resonator antenna having a conventional equivalent circuit can be made into a chip.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a resonator antenna of the present invention.

FIG. 2 is a perspective view showing a resonator antenna of the present invention.

FIG. 3 is an exploded perspective view showing a block body of the resonator antenna shown in FIG.

FIG. 4 is a characteristic diagram showing directional characteristics of the resonator antenna shown in FIG.

FIG. 5 is an illustrative view showing a state where the resonator antenna shown in FIG. 2 is mounted on a printed board.

6 is a plan view showing an example of an antenna electrode of the resonator antenna shown in FIG.

7 is a plan view showing a modified example of the antenna electrode shown in FIG.

FIG. 8 is a plan view showing another modification of the antenna electrode shown in FIG.

FIG. 9 is a plan view showing still another modification of the antenna electrode shown in the nest 6.

FIG. 10 is an exploded perspective view showing another example of the present invention.

11 is a characteristic diagram showing directional characteristics of the resonator antenna shown in FIG.

FIG. 12 is an equivalent circuit diagram of a conventional resonator antenna which is the background of the present invention.

13A is a plan view showing the structure of a conventional resonator antenna, and FIG. 13B is a side view thereof.

FIG. 14 is a circuit diagram showing a state in which a matching circuit is added for impedance matching in a conventional resonator antenna.

[Explanation of symbols]

 10 Resonator Antenna 12 Dielectric Layer 14 Antenna Electrode 16 Shield Electrode 18 Earth Terminal 24a to 24l External Electrode L Inductance L1, L2 Inductance Part C1 Capacitance F Feeding Point

Claims (2)

[Claims] 1. A resonator antenna having an equivalent circuit composed of an inductance and a capacitance, wherein the inductance comprises two inductance parts, and a midpoint between the two inductance parts serves as a feeding point. Vessel antenna. 2. A linear or planar antenna electrode formed on one main surface of the dielectric layer, and a planar shield electrode formed on the other main surface of the dielectric layer, the antenna electrode A resonator antenna, wherein the shield electrode is connected to an external electrode formed on a side surface of the dielectric layer, and a connection point between the antenna electrode and the shield electrode is a feeding point.