JPH10126141A - Surface mounted antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the surface mount antenna with a high gain that is made small in size and an electromagnetic wave emitted from which is used efficiently for communication. SOLUTION: A ground conductor film 16 is formed on a lower side of a dielectric board, a radiation conductor film 12 tying two left/right ends 12a, 12b close to each other while circulating within a horizontal plane as a loop and inner feeding conductor films 13, 14 connecting respectively to the two ends 12a, 12b respectively and exposed to a side face of a dielectric base 11 are provided in the inside of the dielectric base 11. Side feeding conductor films 18, 19 which extend parallel in the vertical direction, connected to the parts exposed to the side of the inner feeding conductor films 13, 14 and one of which is connected to a ground conductor film 16 are formed on a side face of the dielectric base 11.

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 mounted on a circuit board incorporated in a portable communication device or the like.

[0002]

2. Description of the Related Art As an antenna used in a portable communication device, an antenna which is small in size, high in gain, low in cost and easy to mount is required. On the other hand, conventional linear antennas such as dipole antennas and monopole antennas have a large volume, which hinders the miniaturization of communication devices. It is difficult to use it for portable communication devices and the like that are required to be used.

Some antennas have been proposed to solve such a problem. FIG.
FIG. 1 is a perspective view showing a so-called antenna proposed in Japanese Patent No. 5825. Dielectric substrate 91 constituting antenna 90
A radiation conductor film 92 is formed on the entire surface of the substrate. A ground conductor film 93 is formed on the back surface of the dielectric substrate 91. The ground conductor film 93 has a shape in which a part of one of the two short sides is cut out, and an excitation conductor film 94 is formed in the cut out part. Further, a power supply electrode 95 is formed on a side surface of the dielectric substrate 91. The power supply electrode 95 is connected to the excitation conductor film 94. A power supply electrode 95 is provided on a side surface of the dielectric substrate 91.
Are grounded, and ground electrodes 96 and 97 are formed. These ground electrodes 96 and 97 are connected to a ground conductor film 93. In the dielectric substrate 91, a through hole 98 having a conductor on the inner wall is formed.
8, the tip of the radiation conductor film 92 and the tip of the excitation conductor film 94 are electrically connected.

The antenna 90 configured as described above is surface-mounted on a circuit board built in a communication device main body, and radiated from the communication device main body via a power supply electrode 95, an excitation conductor film 94, and a through hole 98. High-frequency power is supplied to the conductor film 92, and electromagnetic waves are radiated from the radiation conductor film 92 into the air by electromagnetic coupling between the excitation conductor film 94 and the radiation conductor film 92.

FIG. 10 is a perspective view showing an antenna proposed in Japanese Patent Laying-Open No. 7-283639. Antenna 1
The through-hole 102 having the radiation conductor film formed on the inner wall is formed in the dielectric substrate 101 constituting 00.
A surface electrode 103 is formed on the surface of the dielectric substrate 101, and a connector external conductor plate 104 is attached to the back surface. The surface electrode 103 and the connector external conductor plate 104 It is electrically connected by the radiation conductor film formed on the inner wall. further,
A coaxial connector 105 is mounted on a surface of the connector outer conductor plate 104 opposite to a surface on which the dielectric substrate 101 is mounted.
Outer conductor and inner conductor of the connector outer conductor plate 10
4 and the radiating conductor film in the through hole 102.

[0006] The antenna 100 thus configured is
When the coaxial connector 105 is connected to a connector provided in the communication device main body, the coaxial connector 105 is disposed outside the communication device main body. Electromagnetic waves are radiated from the radiation conductor film formed on the inner wall of the hole 102.

FIG. 11 is a perspective view showing an antenna proposed in Japanese Patent Application Laid-Open No. 7-221537. Antenna 1
A through hole 112 having a radiation conductor film formed on the inner wall thereof is formed in the dielectric substrate 111 constituting the substrate 10 in the long side direction of the dielectric substrate 111. Further, a side surface electrode 113 is formed on the entire surface of one end surface of the dielectric substrate 111, and a power supply electrode 114 is formed on a central portion of the other end surface.
The side electrode 113 and the power supply electrode 114 are
12 are electrically connected by a radiation conductor film formed on the inner wall. Further, side electrodes 115 and 116 are formed on the surface of the dielectric substrate 111 on which the power supply electrodes 114 are formed so as to sandwich the power supply electrodes 114.

[0010] The antenna 110 thus configured is mounted on a circuit board built in the communication device main body.
0 is supplied with high-frequency power, and electromagnetic waves are emitted from the radiation conductor film on the inner wall of the through hole 112.

[0009]

However, in order to increase the gain, the antenna 90 shown in FIG. 9 needs to narrow the frequency band of the electromagnetic wave.
If the frequencies of the transmitted and received electromagnetic waves are different, the antenna 9
It is difficult to use 0 as a transmitting / receiving antenna.

The antennas 100 and 110 shown in FIGS. 10 and 11 are omnidirectional in a plane extending perpendicularly to the direction in which the through-hole in which the radiation conductor film is formed. When such an antenna is mounted on, for example, a mobile phone, the mobile phone generally transmits and receives vertically polarized electromagnetic waves. Therefore, the antenna has the same direction in which the through hole extends and the longitudinal direction of the mobile phone main body. It is mounted on the mobile phone so that

[0011] When a person actually uses a mobile phone on which an antenna is mounted as described above, the antenna is omnidirectional in a plane perpendicular to the direction in which the through-hole extends. The part is irradiated in the direction of the human body. There is a problem that the electromagnetic waves irradiated in the direction of the human body are absorbed by the human body, are not used for communication, and may impair the health of the human body.

The present invention has been made in view of the above circumstances, and has as its object to provide a surface-mounted antenna which can be miniaturized, has high gain, and efficiently uses emitted electromagnetic waves for communication.

[0013]

To achieve the above object, the surface mount antenna of the present invention comprises: (1) a dielectric substrate having a lower surface; and (2) a ground formed on the lower surface of the dielectric substrate and extending in a planar manner. Conductive film (3) Radiating conductor film having two ends adjacent to the left and right formed inside the dielectric substrate and looping around in a horizontal plane to connect these two ends. (4) The dielectric film An internal power supply conductor film formed between the two ends of the radiation conductor film and the side surface of the dielectric substrate formed inside the body substrate; and (5) an upper and lower surface formed on the side surface of the dielectric substrate in parallel with each other. And a side power supply conductor film extending in the direction and connected to each of the internal power supply conductor films, one of which is connected to the ground conductor film.

In the surface-mounted antenna of the present invention, a radiation conductor film is formed inside the antenna in a loop in a horizontal plane, and a ground conductor film extending in a planar shape is formed on the lower surface. The electromagnetic wave having the maximum gain is radiated from the film in a direction perpendicular to the plane including the radiation conductor film, and the electromagnetic wave of the radiated electromagnetic wave directed to the ground conductor film is reflected by the ground conductor film. That is, the antenna emits an electromagnetic wave having a maximum gain in a direction perpendicular to the plane including the radiation conductor film and in a direction from the ground conductor film to the radiation conductor film.
Therefore, when such an antenna is attached to a mobile phone, for example, when a human uses the mobile phone so that the ground conductor film is located between the human and the radiation conductor film, electromagnetic waves are not transmitted to the human side. Is not radiated, and the radiated electromagnetic wave has a maximum gain in the direction from the ground conductor film to the radiation conductor film, and is used for communication efficiently.

By the way, in electromagnetic waves of the same frequency,
Comparing the wavelength of the electromagnetic wave in air with the wavelength of the electromagnetic wave in the dielectric, the wavelength of the electromagnetic wave in the dielectric is shorter. Therefore, comparing the case where the radiating conductor film is formed inside the dielectric substrate and the case where the radiating conductor film is formed on the surface of the dielectric substrate, when the same frequency of electromagnetic waves is radiated, the radiating conductor film is formed inside. By doing so, the length of the loop of the radiation conductor film can be shortened. When the length of the loop of the radiation conductor film can be reduced in this way, the size of the dielectric substrate can be reduced.

Therefore, in the surface mount antenna according to the present invention in which the radiation conductor film is formed inside the dielectric substrate, downsizing can be realized. Here, in the surface-mounted antenna of the present invention, it is preferable that the feeding conductor film of the surface-mounted antenna also serves as an electrode when the surface is mounted on the circuit board. Since the power supply conductor film also serves as an electrode when surface-mounted on the circuit board, the surface-mounted antenna can be easily mounted on the circuit board.

[0017]

Embodiments of the present invention will be described below. FIG. 1 shows a first example of the surface mount antenna of the present invention.
2 is a top view, FIG. 3 is a bottom view, and FIG. 4 is a side view of the embodiment. As shown in FIG. 2, the inside of a rectangular parallelepiped dielectric substrate 11 constituting the surface-mounted antenna 10 shown in FIG.
A radiating conductor film 12 having two ends 12a and 12b and connecting the two ends 12a and 12b is formed around the horizontal plane in a loop, and the length of the radiating conductor film 12 is determined by the length of the transmission target. The length of the electromagnetic wave is adjusted to the same length as the resonance wavelength of the dielectric substrate 11. Also, the dielectric substrate 11
In the plane including the radiation conductor film 12 inside, the internal power supply conductor films 13 and 14 connected to the two ends 12a and 12b of the radiation conductor film 12 and exposed on the side surfaces of the dielectric substrate 11 are formed. And the internal power supply conductor films 13 and 1
4 have a gap 15 between each other, forming a coplanar line between each other. On the lower surface of the dielectric substrate 11,
As shown in FIG. 3, a ground conductor film 16 is formed, and this ground conductor film 16 has a shape in which one side is partially cut away. Further, as shown in FIG. 4, the side surfaces of the dielectric substrate 11 extend in the vertical direction in parallel so as to have a gap 17 therebetween, and as shown in FIG.
14 are formed on side exposed portions of the side-surface feeding conductor films 18 and 19 connected to respective portions exposed to the side surfaces and forming coplanar surfaces with each other. The power supply conductor film 19 is also connected to the ground conductor film 16, and the other side power supply conductor film 18 is connected to the dielectric substrate 1.
1 has reached the lower surface. In addition, the side surface feeding conductor film 18,
The 19 side of the ground conductor film 16 also serves as feed electrodes 20 and 21 which are electrodes when the surface is mounted on the circuit board.

The antenna 10 configured as described above includes
The radiation conductor film 1 has a wavelength loop antenna structure.
2, when a current is supplied to the radiation conductor film 12 via the feed electrode 20, an electromagnetic wave having the maximum gain is radiated from the radiation conductor film 12 in a direction perpendicular to a plane including the radiation conductor film 12. The electromagnetic wave traveling toward the ground conductor film 16 is reflected by the ground conductor film 16. Therefore, it is possible to obtain an antenna with high gain and in which radiated electromagnetic waves are efficiently used for communication.

The surface-mount antenna 10 has internal feeding conductor films 13 and 14 forming a coplanar line between each other.
And side power supply conductor films 18 and 19 forming a coplanar line between each other.
3, 14, the width of each side power supply conductor film 18, 19, the gap width of the gap 15 between the internal power supply conductor films 13, 14,
A desired transmission impedance can be obtained by manufacturing the surface-mounted antenna 10 in which the gap width of the gap 17 between the side-surface feeding conductor films 18 and 19 is adjusted.

Further, the surface mount antenna 10 has the radiation conductor film 12 formed therein, so that downsizing can be realized. In the surface-mounted antenna 10, the side of the grounding conductor film 16 of the feeding conductor films 18 and 19 is connected to the feeding electrode 2 respectively.
Since they also serve as 0 and 21, they are easily mounted on a circuit board by soldering or the like.

The surface mount antenna 1 shown in FIG.
0 will be described with reference to FIGS. 1, 5, and 6. FIG. FIG. 5 is a top view of the surface-mounted antenna 10, showing the length and width of the dielectric substrate, the dimensions of the radiation conductor film and the internal feeding conductor film, and FIG.
FIG. 4 is a side view of FIG. 5, showing the thickness of the dielectric substrate and the dimensions of the side-surface feeding conductor film.

First, a material for the dielectric substrate is selected. The dielectric material is preferably a material whose relative dielectric constant is stable at about 10 to 100 in the frequency band of the transmitted / received electromagnetic wave. Further, in the surface mount antenna 10,
Since the radiation conductor film 12 is formed inside the dielectric substrate 111 as shown in FIG. 1, a material that can be fired at a low temperature is preferable. For example, a material obtained by adding glass to an Sr (Ni _1/3 Nb _2/3 ) O ₃ ceramic is preferable. This material has a relative dielectric constant of 25, a Q value of 1000, and a firing temperature of 10 when the frequency of transmitted and received electromagnetic waves is 6 GHz.
00 ° C.

Next, the radiation conductor film 12, the internal power supply conductor film 1
The dimensions of the third and fourth side conductor films 18 and 19 and the dielectric substrate 11 are determined. These dimensions can be determined as follows. Assuming that the length of the radiation conductor film 12 is λ, λ can be represented by the following equation. λ = λ ₀ / √ (ε _reff ) (1) where λ ₀ : wavelength of electromagnetic wave in vacuum ε _reff : effective relative permittivity In the surface-mounted antenna 10, the radiation conductor film 12 is formed inside the dielectric substrate 11. _Therefore , ε _reff matches the dielectric constant ε _{r of the} dielectric substrate 11. Therefore, λ
Is represented by the following equation.

Λ = λ ₀ / √ (ε _r ) (2) Assuming that the resonance frequency of the electromagnetic wave is 1.9 GHz, λ = 3
The radiation conductor film 12 as shown in FIG.
Is formed, the length of one side of the radiation conductor film must be 7.8.
What is necessary is just to make it 9 mm. Here, the dashed line shown in FIG. 5 indicates the center line of each side of the radiation conductor film 12. The impedance of the one-wavelength loop antenna is generally a high impedance of 100Ω or more, but the impedance is reduced by adjusting the width of the radiation conductor film and the interval between the two ends of the radiation conductor film to reduce the power supply efficiency. Can be improved. For example, to set the impedance to 50Ω,
As shown in FIG. 5, the width of the radiation conductor film may be 2 mm, and the distance between the two ends may be 0.4 mm.

In order to form the radiation conductor film whose dimensions are determined as described above, for example, the distance from the side surface of the dielectric substrate 11 to the outer peripheral edge of the radiation conductor film 13 is 1 mm as shown in FIG. In this case, the length and width of the dielectric substrate 11 may be set to 11.89 mm. The thickness of the dielectric substrate is determined as follows. The gain of the antenna having the loop antenna structure as shown in FIG. 1 is such that the distance between the radiating conductor film and the ground conductor film formed on the lower surface of the dielectric substrate is equal to the resonance wavelength of the electromagnetic wave to be transmitted and received. Is the highest when it has a distance corresponding to a quarter wavelength in the above. Therefore, assuming that the resonance frequency of the electromagnetic wave is 1.9 GHz, in order to maximize the gain of the antenna, the distance between the radiation conductor film and the ground conductor film has a resonance frequency of 1.9 GHz as shown in FIG. The distance may be 7.89 mm, which is equivalent to a quarter wavelength of the resonance wavelength of the electromagnetic wave in the dielectric substrate, and the distance between the radiation conductor film 12 and the upper surface of the dielectric substrate 11 may be, for example. Is set to be 2 mm, the thickness of the dielectric substrate may be 9.89 mm as shown in FIG. That is, the length, width, and thickness of the dielectric substrate 11 are each set to 1
What is necessary is just 1.89 mm, 11.89 mm, 9.89 mm.

The desired transmission impedance can be obtained by adjusting the width of the internal power supply conductor film, the gap width of the gap between the internal power supply conductor films, and the width of the side power supply conductor film and the gap width of the gap between the side power supply conductor films. Is obtained. For example, in order to set the transmission impedance to 50Ω, as shown in FIG. 5, the width of each of the internal power supply conductor films 13 and 14 is 0.35 mm, and the width of the gap 15 is 0.40 m.
m, the width of each of the side surface feeding conductor films 18 and 19 is 1.69 mm, and the gap width of the gap 17 is 0.40 mm as shown in FIG.

Next, the radiation conductor film 1 having the above-described dimensions is provided inside the dielectric substrate 11 having the above-described dimensions.
2 and the patterns of the internal power supply conductor films 13 and 14, the patterns of the side power supply conductor films 18 and 19 having the dimensions described above on the side surface, and the patterns of the power supply electrode 20 and the ground conductor film 16 on the lower surface. It is printed by a thick film printing method using a copper paste and fired in a reducing atmosphere.

Thus, the surface mount antenna 10 is manufactured. FIG. 7 is a diagram showing a second embodiment of the surface mount antenna according to the present invention. The surface-mounted antenna 70 shown in FIG. 7 has a cylindrical dielectric substrate 71 instead of the rectangular parallelepiped dielectric substrate 11 of the surface-mounted antenna 10 shown in FIG.
Accordingly, the radiation conductor film 72 has a circular loop-shaped radiation conductor film 72, and the ground conductor film has a circular ground conductor film 76.

As described above, the dielectric substrate may have a cylindrical shape. FIG. 8 is a diagram showing a state in which the surface mount antenna shown in FIG. 1 is mounted on a circuit board. A feeder line 82 and a ground conductor layer 83 are formed on the surface of the circuit board 81. The feeder line 82 and the feeder electrode 20 of the surface mount antenna 10, and a ground conductor layer 83 and the ground mount antenna 10
Of the power supply electrodes 21 are connected by solders 84, respectively. Thus, the surface mount antenna 10 is mounted on the circuit board 81.

[0030]

As described above, according to the present invention,
It is possible to obtain a surface-mounted antenna that can be miniaturized, has high gain, and efficiently uses electromagnetic waves for communication.

[Brief description of the drawings]

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

FIG. 2 is a top view of the surface mount antenna shown in FIG.

FIG. 3 is a bottom view of the surface mount antenna shown in FIG. 1;

FIG. 4 is a side view of the surface mount antenna shown in FIG.

FIG. 5 is a diagram showing the length and width of a dielectric substrate, dimensions of a radiation conductor film, and an internal feeding conductor film.

FIG. 6 is a diagram showing the thickness of a dielectric substrate and the dimensions of a side-surface feeding conductor film.

FIG. 7 is a diagram showing a second embodiment of the surface mount antenna of the present invention.

8 is a diagram showing a state in which the surface mount antenna shown in FIG. 1 is mounted on a circuit board.

FIG. 9 is a perspective view showing an antenna proposed in JP-A-7-235825.

FIG. 10 is a perspective view showing an antenna proposed in Japanese Patent Application Laid-Open No. 7-283639.

FIG. 11 is a perspective view showing an antenna proposed in Japanese Patent Application Laid-Open No. 7-221537.

[Explanation of symbols]

 10, 70 Surface mount antenna 11, 71 Dielectric substrate 12, 72 Radiating conductor film 13, 14 Internal feeding conductor film 15, 17 Gap 16, 76 Grounding conductor film 18, 19 Side feeding conductor film 20, 21 Feeding electrode 81 Circuit Substrate 82 Power supply line 83 Ground conductor layer 84 Solder

Claims (2)

[Claims] 1. A dielectric substrate having a lower surface, a planar grounding conductor film formed on a lower surface of the dielectric substrate, and a left and right adjacent 2 formed inside the dielectric substrate.
Having two ends and looping around in a horizontal plane
A radiation conductor film connecting two ends, an internal power supply conductor film formed inside the dielectric substrate and connecting each of two ends of the radiation conductor film to a side surface of the dielectric substrate, A side surface power supply conductor film formed on a side surface and extending in a vertical direction in parallel with each other and connected to each of the internal power supply conductor films, one of which is connected to the ground conductor film. Mountable antenna. 2. The surface-mounted antenna according to claim 1, wherein the side-surface feeding conductor film also serves as an electrode when the surface is mounted on a circuit board.