JPH10173425A - Surface mount antenna and antenna device and communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain miniaturization without using a dielectric substrate with a high dielectric constant, and to attain low frequencies without large-scaling a dielectric substrate by realizing the pattern of a radiation electrode going from a first main surface through an edge face to a second main surface back and forth. SOLUTION: In a dielectric substrate 11, electrodes 1c, 2c, 3c, and 1g are formed on an upper surface (a first main surface), electrodes 1a, 2a, 3a, and 1e are formed on a lower surface (a second main surface), electrode 1b, 2b, and 3b are formed on a front left edge face, and electrodes 1d and 1f are formed on a back right edge face. The electrodes 1a, 1b, 1c, 1d, 1e, 1f, and 1g are continuously formed in this order so that a radiation electrode 1 can be formed. Also, the electrodes 2a, 2b, and 2c are continuously formed in this order so that a power feeding electrode 2 can be constituted. Moreover, the electrodes 3a, 3b, and 3c are continuously formed in this order so that a ground electrode 3 can be constituted. The radiation electrode 1 is constituted so as to be folded from the upper surface through the back right edge face of the dielectric substrate 11 to the lower surface so that the length of the radiation electrode 1 can be made longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount antenna used for mobile communication equipment, an antenna device using the surface mount antenna, and a communication device.

[0002]

2. Description of the Related Art As a surface mount antenna of this type, the present applicant has filed an application in Japanese Patent Application No. 08-158153, which facilitates miniaturization and frequency adjustment. One embodiment shown in the application will be briefly described with reference to FIG. FIG. 15 is a view showing the configuration of the surface mount antenna shown in FIG. 1 in the drawings of the above-mentioned application, but the numbers in the figure are changed. In FIG. 15, a surface-mounted antenna includes a dielectric substrate 11 and, as shown by 1a, 1b, and 1c, U-shaped radiation electrodes 2a and 2b formed on the surface of the substrate 11 from the back surface to the side surface. , 2c, a power supply electrode formed on the front surface from the back surface via the side surface;
As shown by a, 3b and 3c, it is composed of a ground electrode formed on the front surface from the back surface via the side surface. And
The portion indicated by 1a of the radiation electrode and the portion indicated by 3a of the ground electrode are grounded, and a high-frequency signal source is connected to the feed electrode 2a. By forming the open end of the radiation electrode 1 and the power supply electrode 2 to be spatially separated in this manner, excitation by capacitive coupling is achieved.

[0003]

In the conventional surface mount antenna shown in FIG. 15, as the dielectric substrate having a higher relative dielectric constant is used, a greater wavelength shortening effect is obtained and the overall size can be reduced. However, when a dielectric substrate having a high relative dielectric constant is used, the Q of the antenna increases, and as a result, there is a problem that a usable frequency band is narrowed. Also,
In order to reduce the frequency band to be used without increasing the overall size, in order to obtain a required inductance component, for example, a method in which the radiation electrode has a meander structure as shown in FIG. 16 can be considered. However, it is difficult to form a radiating electrode having a large inductance component within a limited area of the dielectric substrate simply by using the meander structure, and furthermore, the reverse current flowing between adjacent meander portions of the radiating electrode is difficult. A problem arises in that the antenna gain is reduced due to the canceling action of.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface-mounted antenna which has been reduced in size without using a dielectric substrate having an extremely high relative permittivity and has been designed to reduce the frequency without increasing the size of the dielectric substrate. An object of the present invention is to provide an antenna device and a communication device using the same.

[0005]

SUMMARY OF THE INVENTION According to the present invention, an open end is provided on a base made of a dielectric or magnetic material having first and second main surfaces facing each other and an end surface substantially perpendicular to these main surfaces. ,
A radiation electrode having the other end as a ground end, a ground electrode in which capacitance is generated between an open end of the radiation electrode, and a feeding electrode in which capacitance is generated between the radiation electrode and capacitive coupling. 2. A surface-mounted antenna formed with, for efficiently increasing an inductance component of a radiation electrode.
As described in the above, the base extends from the first main surface to the second main surface via at least one end surface, forms a pattern of a predetermined length on the second main surface, and again passes through the at least one end surface. To return to the first main surface.

The present invention also provides a base made of a dielectric or magnetic material having first and second main surfaces facing each other and an end surface substantially perpendicular to these main surfaces, one end of which is open and the other end is provided. A surface mount antenna in which a radiation electrode serving as a ground end and a feed electrode that generates capacitance between the vicinity of the open end of the radiation electrode and capacitive coupling are formed, and the inductance component of the radiation electrode is efficiently reduced. As described in claim 2, the base extends from the first main surface of the base via at least one end surface to the second main surface, and a pattern of a predetermined length is formed on the second main surface. In this case, the folded shape returns to the first main surface via at least one end surface.

[0007] With this structure, the radiation electrode has a pattern of reciprocating between the first main surface and the second main surface via the end face, and the entire pattern length is increased, so that a necessary large inductance component can be easily obtained. Therefore, the overall size can be reduced without using a dielectric substrate having an extremely high relative permittivity, the Q can be kept low, and the band can be prevented from being narrowed. Further, it is possible to reduce the frequency without increasing the size of the dielectric substrate.

Further, according to a third aspect of the present invention, the surface mount type antenna is mounted on a dielectric plate having a dielectric constant lower than the dielectric constant of the base by using the second main surface of the base as a mounting surface. To implement the antenna device. With this structure, a part of the radiation electrode formed on the second main surface of the base comes into contact with the dielectric plate. However, the dielectric constant of the base of the surface mount antenna is the dielectric constant of the mounting dielectric plate. , The change in the resonance frequency due to mounting is reduced.

According to another aspect of the present invention, there is provided an antenna device having the above-described surface-mounted antenna, an antenna device having the mounting structure thereof, and a communication device using the same. A circuit board provided with an electrode non-forming portion and an electrode for connection with a surface-mount antenna on the mounting portion, wherein the surface-mount antenna according to claim 1 or 2 is provided on the mounting portion of the circuit board. Implement. By using the circuit board in which the front and back surfaces of the mounting portion of the surface mount antenna have no electrodes, the electrodes are not affected by the electrodes on the circuit board. Also, the second principal surface of the surface mount antenna comes into contact with the dielectric portion which is the substrate of the circuit board. Generally, the dielectric constant of the substrate of the circuit board is low, and the dielectric constant of the base of the surface mount antenna is low. Is higher, the change in the resonance frequency due to mounting is reduced. Therefore, a communication device having stable characteristics can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a surface mount antenna according to a first embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 11 denotes a dielectric substrate made of dielectric ceramics, a synthetic resin having a relatively high dielectric constant, or the like, and 1c, 2c, 3 is provided on the upper surface (first main surface) in FIG.
Electrodes denoted by c, 1g are formed, and electrodes denoted by 1a, 2a, 3a, 1e are formed on the lower surface (second main surface) in the figure of the dielectric substrate 11, and an end surface of the dielectric substrate 11 on the left front side in the figure. The electrodes indicated by 1b, 2b and 3b are formed on the right side, and the electrodes indicated by 1d and 1f are formed on the right rear end face of the dielectric substrate 11 in the figure. Electrodes 1a, 1b, 1
c, 1d, 1e, 1f, 1g are consecutive in this order,
The radiation electrode 1 is formed. Further, 2a, 2b, and 2c are continuous in this order, and constitute the power supply electrode 2. 3a, 3
b and 3c are continuous in this order and constitute the ground electrode 3.

In FIG. 1, the electrodes 4a and 4b are formed when the surface mount antenna 10 is cut out from a dielectric mother substrate, and the electrodes 2a and 2b of another adjacent dielectric substrate are formed.
These electrodes are continuous from c. Of these, the lower electrode 4a in the figure is used as a mounting dummy electrode when mounted on a circuit board.

FIG. 2 shows the surface mount antenna 1 shown in FIG.
It is an equivalent circuit diagram of 0. In FIG. 2, the surface-mounted antenna includes an inductor L, a resistor R, and capacitors C13 and C1.
2, C22. 1, the inductor L is mainly composed of the electrodes 1b, 1c, 1d, 1
e, 1f, 1g, the self-inductance of the radiation electrode, the capacitor C13 is the capacitance formed between the open end of the radiation electrode (near the tip of the electrode 1g) and the ground electrode 3c, and the capacitor C12 is the capacitance of the radiation electrode. The capacitance formed between the open end and the power supply electrode, and the capacitor C22 is the capacitance formed between the power supply electrode 2 and the ground electrode 3 and between the electrode 1a serving as the ground end of the radiation electrode. is there. And
The resistance R is the radiation resistance of the surface mount antenna.

In the equivalent circuit shown in FIG. 2, the resonance circuit mainly includes an inductor L, a resistor R, and a capacitor C13. When a signal is input from a high-frequency signal source to the resonance circuit via the capacitor 12, the energy resonates in the resonance circuit, and a part of the energy is radiated into the air to function as an antenna. This radiant energy is equivalent to the resistance R
Expressed as energy consumed in

As described above, the resonance frequency of the surface mount antenna is determined by the value of the inductor L if the value of the capacitor C13 is constant, and the inductor L is determined mainly by the length of the radiation electrode 1 shown in FIG. So Figure 1
As shown in the figure, the radiation electrode 1 is folded back from the upper surface (first principal surface) to the lower surface (second principal surface) via the right rear end face of the dielectric substrate 11 in the drawing. , The required large inductance can be obtained, and the whole can be easily reduced in size without using a dielectric substrate having an extremely high relative dielectric constant. Further, the frequency can be reduced without reducing the size of the dielectric substrate 11.

As the dielectric substrate, a magnetic material having dielectric properties may be used other than the dielectric plate. In this case, 1 /
Since the wavelength shortening effect of の (ε × μ) is obtained, the magnetic permeability μ
By using a magnetic material having a high refractive index, a large wavelength shortening effect can be obtained. Further, since μ / ε determines the impedance of the electrode, the impedance is increased by using a magnetic material having a high μ. This makes it possible to reduce the Q of an antenna that is too high and obtain wideband characteristics.

FIG. 3 is a perspective view showing the configuration of the antenna device according to the second embodiment of the present invention. In FIG.
Reference numeral 6 denotes a circuit board formed by forming various electrode patterns on the front and back surfaces of a dielectric plate 12, and the surface-mounted antenna 10 shown in FIG. The ground electrode 13 and the power supply electrode 15 are formed on the upper surface of the circuit board 16 in the drawing, and the ground electrode 14 is formed on the lower surface in the drawing. However, no electrodes other than the mounting electrodes are formed on the upper and lower surfaces of the circuit board 16 in the mounting portion of the surface mount antenna 11 indicated by A. That is, this A
The portions indicated by the symbols 1a, 2a, 3a, and 4 shown in FIG.
An electrode is formed at a position facing each electrode shown by a,
Each part is connected and fixed by soldering.

FIG. 4 is a partially cutaway perspective view showing the configuration of a communication device according to the third embodiment. In FIG. 4, reference numeral 20 denotes a casing of the communication device 100 in which the circuit board 16 is housed. The mounting structure of the surface-mounted antenna 10 on the circuit board 16 is the same as that shown in FIG. 3. The circuit board 16 has a wiring pattern formed thereon and other surfaces for forming a circuit required as a communication device. The mounted components are mounted.
By thus surface-mounting the surface-mounted antenna 10 on the circuit board, a communication device such as a small-sized mobile phone having the antenna built therein can be easily configured.

Next, configuration examples of the surface mount antenna according to the fourth to seventh embodiments will be described with reference to FIGS.

In the example shown in FIG. 5, a gap portion between the open end of the radiation electrode 1 and the ground electrode 3 is formed on the upper surface of the dielectric substrate 11 in FIG. On the other hand, in FIG. 5, the dielectric substrate 11 is formed on the left front end face in the figure. That is, the ground electrode 3 is shortened, and the electrode 1h further extending from the electrode 1g is formed on the left end face of the dielectric substrate 11. With this configuration, the inductance of the radiation electrode 1 can be further increased.

In the example shown in FIG. 6, compared to the case shown in FIG.
The length of the electrode 1e on the lower surface side of the dielectric substrate 11 in the drawing is increased to increase the overall length of the radiation electrode.

In the example shown in FIG. 7, the pattern of the electrode 1e on the lower surface side of the radiation electrode 1 in the drawing is formed in a semicircular shape.

In the example shown in FIG. 8, the lower electrode 1e is formed in a meandering shape to increase the entire length of the radiation electrode 1. There is a concern that the antenna efficiency may be reduced by forming the radiation electrode in a meandering shape. However, the antenna efficiency is not significantly reduced since the entire radiation electrode is not in a meandering shape.

Next, the configuration of a surface mount antenna according to an eighth embodiment will be described with reference to FIGS.

FIG. 9 is a perspective view of the surface mount antenna. Unlike the antenna shown in FIG. 1, in this example, the ground electrode 3 is not provided, and the feed electrode 2 and the open end of the radiation electrode 1 are opposed to each other. Therefore, power is supplied from the gap. That is, 1a, 1b, 1c, 1d, 1e, 1f, 1
g is formed on the dielectric substrate 11 to form a radiation electrode 1.
And the electrodes shown by 2a, 2b, and 2c are configured as the power supply electrode 2, and the tips of the electrodes 1g and 2c are opposed to each other.

FIG. 10 is an equivalent circuit diagram of the surface mount antenna shown in FIG. Here, the inductor L is the inductance component of the radiation electrode 1 shown in FIG. 9, C11 is the capacitance between the vicinity of the open end of the radiation electrode and the ground, and C12 is the capacitance between the feed electrode 2 and the radiation electrode 1. It is capacitance. Even in a surface mount antenna having such a structure,
Since the resonance frequency is determined by the inductance of the radiation electrode 1, by making the radiation electrode 1 folded as shown in FIG. 9, the overall size and frequency can be reduced.

Next, ninth to first examples of other surface mount antennas for feeding power from the gap between the feeding electrode and the radiation electrode will be described.
A second embodiment is shown in FIGS.

In the example shown in FIG. 11, a gap between the radiation electrode 1 and the feed electrode 2 is formed on the left end face of the dielectric substrate 11 in the figure.

In the example shown in FIG. 12, the length of the electrode 1e on the lower surface side of the dielectric substrate 11 in the figure of the dielectric substrate 11 is made longer than in the case of the radiation electrode 1 shown in FIG. .

In the example shown in FIG. 13, the pattern of the electrode 1e on the lower surface side in the drawing of the radiation electrode 1 is formed in a semicircular shape.

In the example shown in FIG. 14, the electrode 1e on the lower surface side is formed in a meander shape to increase the entire length of the radiation electrode 1.

[0032]

According to the first and second aspects of the present invention, the radiation electrode has a pattern of reciprocating between the first main surface and the second main surface via the end face, and the entire pattern length becomes longer, which is necessary. A large inductance component can be easily obtained. Therefore, the overall size can be reduced without using a dielectric substrate having an extremely high relative permittivity, the Q can be kept low, and the band can be prevented from being narrowed. Further, it is possible to reduce the frequency without increasing the size of the dielectric substrate.

According to the third aspect of the present invention, the second substrate
A part of the radiation electrode formed on the main surface comes into contact with the dielectric plate. However, since the dielectric constant of the substrate of the surface mount antenna is higher than the dielectric constant of the dielectric plate for mounting, resonance due to mounting is not possible. Frequency changes are reduced.

According to the fourth aspect of the present invention, there is no influence from the electrodes on the circuit board. Further, since the dielectric properties of the dielectric portion which is the base material of the circuit board are not affected, a communication device having stable characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a surface mount antenna according to a first embodiment.

FIG. 2 is an equivalent circuit diagram of the surface mount antenna of FIG.

FIG. 3 is a perspective view illustrating a structure of an antenna device according to a second embodiment.

FIG. 4 is a partially cutaway perspective view showing a structure of a communication device according to a third embodiment.

FIG. 5 is a perspective view of a surface mount antenna according to a fourth embodiment.

FIG. 6 is a perspective view of a surface mount antenna according to a fifth embodiment.

FIG. 7 is a perspective view of a surface mount antenna according to a sixth embodiment.

FIG. 8 is a perspective view of a surface mount antenna according to a seventh embodiment.

FIG. 9 is a perspective view of a surface mount antenna according to an eighth embodiment.

FIG. 10 is an equivalent circuit diagram of the surface mount antenna of FIG. 9;

FIG. 11 is a perspective view of a surface mount antenna according to a ninth embodiment.

FIG. 12 is a perspective view of a surface mount antenna according to a tenth embodiment.

FIG. 13 is a perspective view of a surface mount antenna according to an eleventh embodiment.

FIG. 14 is a perspective view of a surface mount antenna according to a twelfth embodiment.

FIG. 15 is a perspective view showing a configuration of a conventional surface mount antenna.

FIG. 16 is a perspective view showing a configuration example of a surface mount antenna according to the related art.

[Explanation of symbols]

 Reference Signs List 1-radiating electrode 2-feeding electrode 3-ground electrode 4a, 4b-dummy electrode 10-surface mount antenna 11-dielectric substrate 12-dielectric plate 13,14-ground electrode 15-feeding electrode 16-circuit board 20 -Casing 100-Communication device A-Non-electrode formation part

Claims (4)

[Claims] 1. A base made of a dielectric or magnetic material having opposed first and second main surfaces and end surfaces substantially perpendicular to these main surfaces, one end of which is an open end and the other end is a ground end. A surface mount type in which a ground electrode in which capacitance is generated between the radiation electrode and the vicinity of the open end of the radiation electrode, and a feed electrode in which capacitance is generated between the radiation electrode and capacitively coupled is formed. An antenna, wherein the radiation electrode is at least one distance from a first main surface of the base.
The second main surface extends through the two end surfaces, a pattern of a predetermined length is formed on the second main surface, and the folded shape returns to the first main surface again via at least one end surface. Surface mounted antenna. 2. A base made of a dielectric or magnetic material having opposed first and second main surfaces and an end surface substantially perpendicular to these main surfaces, one end of which is an open end and the other end is a ground end. A surface-mounted antenna in which a radiation electrode and a feed electrode that generates a capacitance between the radiation electrode and the vicinity of an open end thereof and that capacitively couples the radiation electrode are formed. At least one from the plane
The second main surface extends through the two end surfaces, a pattern of a predetermined length is formed on the second main surface, and the folded shape returns to the first main surface again via at least one end surface. Surface mounted antenna. 3. A dielectric plate having a dielectric constant lower than the dielectric constant of the base, wherein the second main surface of the base is a mounting surface.
An antenna device comprising the surface-mounted antenna according to claim 1 mounted thereon. 4. A circuit board in which the front and back surfaces of a mounting portion of a surface mount antenna are non-electrode formed portions, and the mounting portion is provided with a connection electrode for connection with the surface mount antenna, and the mounting portion of the circuit board is provided. A communication device comprising the surface-mounted antenna according to claim 1 mounted thereon.