The present disclosure relates to an antenna device.
As an antenna device in the related art, a slot antenna illustrated in
The slot antenna has a microstrip line 202 on a front surface of a dielectric substrate 201, and a conductive layer 203 is arranged on a rear surface of the dielectric substrate 201. In addition, a plurality of slots 204a to 204d is formed in the conductive layer 203. The plurality of slots 204a to 204d receives electric power via the microstrip line 202, thereby realizing emission in a horizontal direction (−X direction) of the dielectric substrate 201. In addition, a cavity-formed reflection plate 205 in which a raising-processed portion 206 is disposed is arranged in the plurality of slots 204a to 204d, thereby achieving antenna performance excellent in a front back ratio (FB ratio).
The technology disclosed in Patent Literature 1 has a difficulty in tilting directivity of an antenna from a horizontal direction.
The present disclosure is made in view of the above circumstances, and provides an antenna device which can suitably tilt the directivity of the antenna.
An antenna device according to the present disclosure includes: a dielectric substrate; a conductive plate which is arranged on one surface of the dielectric substrate; a first slot element to which electric power is supplied from a power supply line, wherein the first slot element has an electrical length having an approximately ½ wavelength of use frequency, and is formed in the conductive plate; a second slot element which has an electrical length longer than that of the first slot element, and which is formed in the conductive plate to be substantially parallel to the first slot element by leaving a gap of an approximately ¼ wavelength of the electrical length from the first slot element; and a ground conductor which is arranged to be substantially parallel to the conductive plate by leaving a predetermined gap from the conductive plate.
According to the present disclosure, it is possible to suitably tilt directivity of an antenna.
In
In
In
In
In
Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.
When an antenna device is mounted on a mobile terminal, a use case illustrated in
In the following embodiment, the antenna device which can suitably tilt the directivity of an antenna will be described.
For example, the antenna device according to the present embodiment is used in a wireless communication circuit of high-frequency (for example, 60 GHz) in a millimeter-wave band. Various electronic components (for example, the antenna and a semiconductor chip) are mounted on the antenna device. For example, the antenna device is operated as a slot antenna.
The antenna device 110 includes a first dielectric substrate 100, a second dielectric substrate 101, a third dielectric substrate 102, a ground conductor 103, a pattern 104, an emission element 105, a reflection element 106, and a power supply line 107. That is, the antenna device 110 has a multilayer substrate. In addition, the pattern 104 has a substantially square shape in a plan view, for example. The pattern 104 is configured to have a metallic conductor (for example, a copper foil).
The first dielectric substrate 100, the second dielectric substrate 101, and the third dielectric substrate 102 are substrates having relative dielectric constant ∈r (for example, 3.6). In addition, the first dielectric substrate 100, the second dielectric substrate 101, and the third dielectric substrate 102 are arranged to be substantially parallel to each other.
In
In the present embodiment, one surface side (+Z side) of the first dielectric substrate 100 is referred to as a first layer (L1 layer), and one surface side (+Z side) of the second dielectric substrate 101 is referred to as a second layer (L2 layer). In addition, one surface side (+Z side) of the third dielectric substrate 102 is referred to as a third layer (L3 layer), and the other surface side (−Z side) of the third dielectric substrate 102 is referred to as a fourth layer (L4 layer).
In
In the L1 layer, for example, a substantially square-shaped pattern 104 formed by the copper foil pattern is arranged on one surface side (+Z side) of the first dielectric substrate 100. The emission element 105 and the reflection element 106 which are formed by cutting out a portion of the pattern 104 in a slot shape are disposed in the pattern 104. The emission element 105 is an example of a first slot element. The reflection element 106 is an example of a second slot element.
The emission element 105 and the reflection element 106 are arranged to be substantially parallel to each other in the L1 layer. In addition, the reflection element 106 is longer than the emission element 105 in a longitudinal direction (Y direction in
The emission element 105 is operated as an emitter for emitting radio waves. Accordingly, a slot length (length in the longitudinal direction of the emission element 105 in
The reflection element 106 is operated as a reflector. Accordingly, a distance d between the emission element 105 and the reflection element 106 is set to be substantially ¼ λg. It is possible to tilt the directivity of the antenna from the horizontal direction (XY direction) or the vertical direction (Z direction) of the substrate by setting the distance d to be substantially ¼ λg. In addition, a slot length L3 of the reflection element 106 (length in the longitudinal direction of the reflection element 106 in
The length from the emission element 105 to an end side of the reflection element 106 side (−X side) in the first dielectric substrate 100 is dx1 (for example, 1.15 λg). The length from the emission element 105 to an end side in an emission direction (+X side) in the first dielectric substrate 100 is dx2 (for example, 2.89 λg).
In the L2 layer, the power supply line 107 is disposed on one surface side (+Z side) of the second dielectric substrate 101. The power supply line 107 is arranged at a position substantially orthogonal to the emission element 105 in a plan view of the XY plane so as to be electromagnetically coupled to the emission element 105.
In addition, the power supply line 107 extends to the L4 layer via a through-hole 108 formed from the L2 layer to the L3 layer, and is connected to a power supply section 109. The power supply section 109 is arranged in an external substrate (for example, a mother board) which is not illustrated, for example.
As described above, the emission element 105 is a power supply element, and the reflection element 106 is a passive element. Accordingly, the power supply line 107 does not need to supply the electric power to a plurality of emission elements, but requires only the length which enables the power supply to the emission element 105. Therefore, it is possible to shorten the length of the power supply line 107 in the L2 layer, and thus, it is possible to suppress a signal loss caused by the power supply line 107.
In the L3 layer, the ground conductor 103 is arranged on one surface side (+Z side) of the third dielectric substrate 102. The ground conductor 103 is arranged to be substantially parallel to the pattern 104 arranged in the first dielectric substrate 100.
In the L4 layer, an electronic component may be mounted on the other surface side (−Z side) of the third dielectric substrate 102. When the electronic component (for example, a semiconductor chip) is mounted on the L4 layer, the ground conductor 103 is arranged between the electronic component and the emission element 105 serving as the antenna or the reflection element 106. This can prevent the electronic component side as well as the antenna side from electrically interfering with each other, thereby improving reliability of the antenna device 110.
The other surface side (−Z side) of the third dielectric substrate 102 is an example of the other surface of the second dielectric substrate 101 on which the electronic component is mounted.
Next, an analysis example of an antenna emission pattern of the antenna device 110 will be described.
In addition,
Next, an example of a change in antenna performance when the length L1 is changed will be described.
Referring to
In addition, referring to
Referring to
As described above, it is possible to obtain a desired tilting angle with high accuracy by setting the length L1 to be from 1.47 λg to 1.8 λg.
Next, current distribution in the antenna device 110 will be described.
Referring to
Accordingly, it is possible to adjust the tilting angle θ to be a desired angle by adjusting the length L1. For example, assuming a case where the antenna device 110 is mounted on the mobile terminal illustrated in
Next, an example of a change in the antenna performance when a length dx2 is changed will be described.
Referring to
Referring to
As described above, it is possible to adjust the tilting angle θ by adjusting the length dx2. For example, assuming a case where the antenna device 110 is mounted on the mobile terminal illustrated in
Next, an example of a change in the antenna performance when a length dx1 is changed will be described.
Here, a main lobe indicates an emission component of the radio wave in a direction having the strongest directivity. A side lobe indicates an emission component of the radio wave in a direction with the second strongest directivity or the subsequent strongest directivity.
In
Referring to
As described above, it is possible to adjust the side lobe level by adjusting the length dx1.
According to the antenna device 110, it is possible to suitably tilt the directivity of the antenna. In addition, for example, it is possible to realize a beam tilt (for example, the tilting angle of 50 degrees to 60 degrees) which is closer to the substrate horizontal direction (XY direction) than the substrate vertical direction (Z direction).
In addition, the electric power is supplied to the emission element 105 by electromagnetic coupling, thereby enabling the power supply line 107 to be shortened. Accordingly, it is possible to reduce a transmission loss in the power supply line 107, and thus, it is possible to improve the antenna performance. Furthermore, high frequency communication is likely to be influenced by the length of the conductor line. Accordingly, it is possible to realize the high frequency communication having little loss by applying the antenna device 110 to millimeter wave communication.
In addition, the ground conductor 103 functioning as a reflection plate can be disposed inside the multilayer substrate in order to prevent the radio wave from being emitted in the −Z direction. Accordingly, it is not necessary to dispose a reflection plate 205 (refer to
In addition, the ground conductor 103 functioning as a ground is arranged between the antenna and the electronic component by mounting the electronic component (for example, a chip component and an integrated circuit (IC)) on the L4 layer. This can suppress electrical interference between the antenna and the electronic component. Accordingly, it is possible to easily modularize the antenna device 110 by excellently maintaining electrical properties thereof.
In addition, the antenna device 110 may be mounted on a receiver side, instead of a transmitter side.
The present disclosure is not limited to the configuration of the above-described embodiment, and can also be applied to any configuration if it is possible to achieve the function disclosed in the scope of claims or the function included in the configuration of the present embodiment.
For example, in the above-described embodiment, the configuration has been described in which the emission element 105 and the reflection element 106 are formed in the pattern 104. However, a waveguide element may be further formed therein. The waveguide element is an example of a third slot element.
Similar to the emission element 105 and the reflection element 106, the waveguide element is formed by being cut out from the pattern 104 into a slot shape. In addition, the waveguide element is arranged to be substantially parallel to the emission element 105, on a side (+X side in FIG. 1) opposite to the side of the reflection element 106 from the emission element 105, by leaving a predetermined distance (for example, approximately ¼ λg) from the emission element 105. In addition, an electrical length of the waveguide element is formed to be shorter than an electrical length of the emission element 105. In addition, two or more of the reflection elements 106 and the waveguide elements may be formed.
It is possible to further improve the directivity in the substrate horizontal direction (XY plane) by providing the waveguide element.
The transmission slot antenna 300 includes the pattern 104 in which the emission element 105 and the reflection element 106 are disposed. The reception slot antenna 400 includes a pattern 503 in which an emission element 501 and a reflection element 502 are disposed. The configuration of the reception slot antenna 400 is the same as the configuration of the transmission slot antenna 300.
The transmission slot antenna 300 is connected to a transmitter 506 via the power supply line 107. The reception slot antenna 400 is connected to a receiver 507 via a power supply line 504.
In
However, it is not necessary to form these in the same shape.
An antenna device according to a first aspect of the present disclosure includes:
a dielectric substrate;
a conductive plate which is arranged on one surface of the dielectric substrate;
a first slot element to which electric power is supplied from a power supply line, wherein the first slot element has an electrical length having an approximately ½ wavelength of use frequency, and is formed in the conductive plate;
a second slot element which has an electrical length longer than that of the first slot element, and which is formed in the conductive plate to be substantially parallel to the first slot element by leaving a gap of an approximately ¼ wavelength of the electrical length from the first slot element; and
a ground conductor which is arranged to be substantially parallel to the conductive plate by leaving a predetermined gap from the conductive plate.
An antenna device according to a second aspect of the present disclosure is the antenna device according to the first aspect further including:
the power supply line, wherein
the power supply line is arranged between the first slot element and the ground conductor, and supplies the electric power by electromagnetic coupling to the first slot element.
An antenna device according to a third aspect of the present disclosure is the antenna device according to the first or second aspect, wherein
a third slot element which has an electrical length shorter than that of the first slot element, and which is formed in the conductive plate to be substantially parallel to the first slot element, by leaving a predetermined gap from the first slot element on a side opposite to the second slot element side.
An antenna device according to a fourth aspect of the present disclosure is the antenna device according to any one of the first to third aspects, wherein
the dielectric substrate is a multilayer substrate,
the conductive plate is arranged on one surface of a first dielectric substrate,
the ground conductor is arranged on one surface of a second dielectric substrate arranged on the other surface side of the first dielectric substrate, and
an electronic component is mounted on the other surface of the second dielectric substrate.
An antenna device according to a fifth aspect of the present disclosure is the antenna device according to any one of the first to fourth aspects, wherein
a length of a side of the conductive plate has an electrical length having a 1.47 wavelength to a 1.8 wavelength of the use frequency of the antenna device.
An antenna device according to a sixth aspect of the present disclosure is the antenna device according to any one of the first to fourth aspects, wherein
the first slot element is arranged by leaving a space of an electrical length having a 1.8 wavelength or more of the use frequency of the antenna device from an end portion of the ground conductor closer to the first slot element than to the second slot element.
An antenna device according to a seventh aspect of the present disclosure is the antenna device according to the first or second aspect, wherein
the second slot element is arranged by leaving a space of an electrical length having a 1.75 wavelength or less of the use frequency of the antenna device from an end portion of the ground conductor closer to the second slot element than to the first slot element.
The present application is based on Japanese patent application No. 2012-289071 filed on Dec. 28, 2012, the contents of which are incorporated herein by reference.
The present disclosure is advantageously applied to an antenna device which can tilt directivity of an antenna from a horizontal direction of a substrate.
Number | Date | Country | Kind |
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2012-289071 | Dec 2012 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/007599 | 12/25/2013 | WO | 00 |