Antenna device

Abstract

To form an approximately equal signal directivity to all circumferential directions of the substrate plane with a simple configuration.SOLUTION: An antenna device is provided, comprising a chip antenna disposed on a substrate and a metal element disposed above or below the chip antenna in a direction perpendicular to the plane of the substrate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an antenna device. [Background technology]

[0002] In recent years, various devices have been equipped with wireless communication functions. Furthermore, there has been active development of antennas to enable such devices to have wireless communication functions. Examples of such antennas include chip antennas, such as those disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-213138 Summary of the Invention [Problem to be solved by the invention]

[0004] In a chip antenna such as that disclosed in Patent Document 1, the directivity of a transmitted signal is determined by an electric field formed according to the direction of current flow. For example, in a typical chip antenna, current flows parallel to the plane of the substrate, making it difficult to form a signal with approximately uniform directivity in all directions around the substrate plane.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to form a signal with approximately uniform directivity in all directions around the substrate plane with a simple configuration. [Means for solving the problem]

[0006] In order to solve the above problem, according to one aspect of the present invention, an antenna device is provided, comprising: a chip antenna placed on a substrate; and a metal element placed on the same substrate as the chip antenna, wherein the metal element is positioned so that its longitudinal direction is perpendicular to the substrate in the direction in which current flows through the chip antenna. [Effects of the Invention]

[0007] As described above, according to the present invention, it is possible to form a substantially uniform signal directivity in all directions around the substrate plane with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 10A and 10B are diagrams for explaining the directivity of a signal transmitted by a chip antenna. [Figure 2] 1 is a diagram illustrating an example of the configuration of an antenna device 10 according to an embodiment of the present invention. [Figure 3] 10 is a diagram showing an example of the arrangement of a chip antenna 120 and a metal element 130 according to the embodiment. FIG. [Figure 4] 10A and 10B are diagrams illustrating the directivity of H polarized waves and V polarized waves by a comparative device including a chip antenna and a metal element that do not satisfy the arrangement conditions according to the embodiment. [Figure 5] 10 is a diagram showing the directivities of H polarized waves and V polarized waves by an antenna device 10 including a chip antenna 120 and a metal element 130 that satisfy the arrangement conditions according to the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0010] <1. Embodiment> <<1.1.Background>> As mentioned above, in recent years, there has been active development of antennas for realizing wireless communication functions in devices.

[0011] The antenna includes, for example, a chip antenna disposed on a substrate. Chip antennas are formed using, for example, high-frequency dielectric ceramics and are excellent in miniaturization and wide bandwidth.

[0012] The directivity of the signal transmitted by a chip antenna is determined by the electric field formed according to the direction of the current flowing through the antenna element, similar to a typical half-wavelength (λ / 2) dipole antenna or a grounded λ / 4 monopole antenna.

[0013] FIG. 1 is a diagram for explaining the directivity of a signal transmitted by a chip antenna.

[0014] Figure 1 shows an image that expresses the directivity of the transmitted signal on three axes: X, Y, and Z, centered on the chip antenna.

[0015] FIG. 1 also shows the directivity of a transmission signal when a current flows in the Z-axis direction in the chip antenna.

[0016] In this case, as shown in the figure, on the two-dimensional plane formed by the X-axis and Y-axis, the directivity of the transmission signal is formed approximately uniformly in all directions around the chip antenna, whereas the directivity of the transmission signal is weaker in the Z-axis direction.

[0017] Furthermore, a chip antenna is usually placed on a substrate so that the antenna element included in the chip antenna is parallel to the substrate.

[0018] In other words, in a typical chip antenna, current flows parallel to the substrate, which weakens the directivity of the transmitted signal in the direction of the current flow, making it difficult to achieve a substantially uniform directivity of the transmitted signal in all directions around the substrate plane.

[0019] However, depending on the application of the device in which the chip antenna is mounted, it may be desirable to form a transmission signal with approximately uniform directivity in all directions around the substrate plane.

[0020] For example, it is assumed that a chip antenna is mounted on a portable device by a user, and the portable device is provided with a wireless communication function.

[0021] The portable device may be, for example, a device that performs wireless communication with a moving object such as a vehicle.

[0022] In this case, the mobile object may perform wireless communication with the portable device, for example, and perform various controls based on the results of the wireless communication.

[0023] Examples of the above control include unlocking control of doors provided in a moving body and engine start control.

[0024] For example, if the authenticity of the portable device is confirmed based on the results of the wireless communication, the mobile object may perform door unlocking control or engine start control.

[0025] Furthermore, for example, the mobile body may perform door unlocking control or engine start control when it is estimated based on the results of wireless communication that the distance between the portable device and the mobile body is less than a specified distance.

[0026] However, when the mobile body performs the above-mentioned control, it is required that wireless communication between the portable device and the mobile body be maintained.

[0027] If wireless communication between the portable device and the mobile body becomes impossible or if the quality of the wireless communication deteriorates significantly, the mobile body will not be able to properly determine the authenticity of the portable device or estimate the distance as described above, and as a result, it will be difficult to properly control the doors and engine.

[0028] To avoid the above situation, it is important that, for example, a signal transmitted from a chip antenna mounted on a portable device is received with good sensitivity by an antenna mounted on a mobile object.

[0029] However, when a user puts a portable device in a pocket, for example, either the front or rear surface of the portable device usually faces the user.

[0030] In this case, in a chip antenna placed on a board that is mounted parallel to the front and rear surfaces of a portable device, the current flows parallel to the front and rear surfaces of the portable device, increasing the H-polarized wave (horizontally polarized wave), which is an electric field component parallel to the board.

[0031] However, in the above situation, H polarized waves are susceptible to the influence of the user's body facing either the front or rear surface of the portable device, and therefore are prone to degradation of characteristics (reduction in gain).

[0032] In this case, the antenna mounted on the mobile object may not be able to receive with sufficient sensitivity the signal transmitted from the chip antenna mounted on the portable device, which may make the above-mentioned control impossible.

[0033] For the reasons mentioned above, when incorporating a chip antenna into a mobile device, it is important to increase not only the H polarization but also the V polarization (Vertically Polarized Wave), which is the electric field component perpendicular to the board and human body.

[0034] This makes it possible to form the directivity of the transmitted signal in all directions around the substrate plane, even in the situation described above where H polarization is easily affected by the human body, and to establish wireless communication using V polarization, which is less affected by the human body.

[0035] An example of the configuration of the antenna device 10 according to this embodiment that achieves the above will be described in detail below.

[0036] <<1.2.Configuration Example>> The antenna device 10 according to this embodiment is a device that transmits and receives radio signals to and from an antenna mounted on another device.

[0037] For example, the antenna device 10 according to the present embodiment may be mounted on a portable device carried by a user, and in this case, the antenna device 10 according to the present embodiment may transmit and receive radio signals to and from an antenna mounted on the mobile object as described above.

[0038] 2 is a diagram illustrating an example of the configuration of the antenna device 10 according to this embodiment. As shown in Fig. 2, the antenna device 10 according to this embodiment includes a chip antenna 120 disposed on a substrate 110, and a metal element 130.

[0039] In FIG. 2, other components that may be disposed on the substrate 110 are omitted.

[0040] 2, for the sake of convenience, chip antenna 120 and metal element 130 are exaggerated. The dimensions of chip antenna 120 and metal element 130 relative to substrate 110 are not limited to the example shown in FIG.

[0041] The same applies to the shapes of chip antenna 120 and metal element 130 according to this embodiment. Chip antenna 120 and metal element 130 according to this embodiment may be formed in a shape different from that shown in FIG.

[0042] (Chip antenna 120) The chip antenna 120 according to this embodiment transmits a signal that complies with a prescribed wireless communication standard.

[0043] The specified communication standard is, for example, ultra-wide band (UWB) wireless communication. When the specified communication standard is ultra-wide band wireless communication, the chip antenna according to this embodiment transmits an ultra-wide band signal.

[0044] However, the prescribed communication standard according to the present embodiment is not limited to the above example. The chip antenna 120 according to the present embodiment may transmit, for example, a signal in the LF (Low Frequency) band or a signal in the UHF (Ultra High Frequency) band.

[0045] (Metal element 130) The metal element 130 according to this embodiment is formed using a conductive metal.

[0046] Furthermore, the metal element 130 according to this embodiment may be a component that is originally provided in the mobile device on which the antenna device 10 is mounted.

[0047] As an example, the metal element 130 according to this embodiment may be a battery that supplies power to the chip antenna 120 .

[0048] By using a component originally required for manufacturing a portable device, such as a battery, as the metal element 130 of this embodiment, it is possible to achieve the effects described below without having to manufacture a new component separately, and even in cases where the internal space is limited, such as in portable devices.

[0049] The metal element 130 according to this embodiment is not limited to a battery, but may be, for example, a metal decoration attached to the housing of a portable device.

[0050] Furthermore, one of the features of the metal element 130 according to this embodiment is that it is disposed above or below the chip antenna 120 in a direction perpendicular to the plane of the substrate 110.

[0051] In the example shown in FIG. 2, metal element 130 is disposed below chip antenna 120 across substrate 110 in a direction perpendicular to the plane of substrate 110.

[0052] According to the above arrangement, the metal element 130 resonates with the electric field formed by the current flowing in chip antenna 120 parallel to substrate 110, and an electric field is also generated in the metal element 130.

[0053] At this time, the electric field generated in the metal element 130 contains many V-polarized wave components that are perpendicular to the plane of the substrate 110.

[0054] According to the above-mentioned action, it is possible to form a substantially uniform signal directivity in the entire circumferential direction of the substrate 110.

[0055] Furthermore, even if H polarization is susceptible to the influence of the human body as described above, it is possible to establish wireless communication using V polarization, which is less susceptible to the influence of the human body.

[0056] In order to achieve the above, it is important to make the metal element 130 resonate effectively.

[0057] For this reason, the metal elements 130 according to this embodiment may be arranged so as to satisfy the conditions described below.

[0058] FIG. 3 is a diagram showing an example of the arrangement of the chip antenna 120 and the metal element 130 according to this embodiment.

[0059] For example, metal element 130 according to this embodiment may be disposed so that distance L1 between chip antenna 120 and metal element 130 is shorter than a specified length determined according to the frequency of the signal transmitted by chip antenna 120.

[0060] Here, the above-mentioned specified length may be a quarter of the wavelength of the frequency of the signal transmitted by the chip antenna 120.

[0061] In this case, metal element 130 according to this embodiment may be arranged so that distance L1 between it and chip antenna 120 is shorter than a quarter of the wavelength of the frequency of the signal transmitted by chip antenna 120.

[0062] That is, the metal elements 130 according to this embodiment may be arranged so as to satisfy the relationship L1<λ / 4.

[0063] According to the above-mentioned arrangement, it is possible to make the metal element 130 resonate effectively, and also to effectively increase the V polarization.

[0064] For example, when metal element 130 is disposed below chip antenna 120 with substrate 110 sandwiched therebetween and GND is formed on the underside of substrate 110, metal element 130 may be disposed so that the distance between metal element 130 and GND is less than λ / 4. In such a case, GND can be considered as part of chip antenna 120.

[0065] In addition to the above conditions, the metal element 130 according to this embodiment may be formed so that its thickness D1 in a direction perpendicular to the plane of the substrate 110 satisfies a specified condition determined by the frequency of the signal transmitted by the chip antenna 120.

[0066] As an example, the metal element 130 according to this embodiment may be formed so that the thickness D1 in the direction perpendicular to the plane of the substrate 110 is equal to or less than the wavelength related to the frequency of the signal transmitted by the chip antenna 120.

[0067] That is, the metal element 130 according to this embodiment may be formed so as to satisfy the relationship of thickness D1≦λ.

[0068] According to the above-described shape, it is possible to make the metal element 130 resonate effectively, and also to effectively increase the V polarization.

[0069] Furthermore, the metal element 130 may be formed so that the thickness D1 is a rounded length relative to the wavelength, such as λ / 4, λ / 2, 3λ / 4, or λ.

[0070] This makes it possible to realize resonance of the metal element 130 more effectively.

[0071] The above-described shape and arrangement can increase the component of current flowing perpendicular to the substrate 110 (in the example shown in FIG. 3, the Z-axis direction), making it possible to more effectively form a substantially uniform directivity of the transmission signal in the entire circumferential direction of the substrate 110.

[0072] Furthermore, it is desirable that the metal element 130 according to this embodiment be placed as close as possible to the power supply point 125 that supplies power to the chip antenna 120 .

[0073] For example, in the case where it is structurally difficult to bring the power supply point 125 according to this embodiment into contact with the metal element 130, the metal element 130 may be arranged close to the power supply point 125 with the distance L3 between the metal element 130 and the power supply being longer than 0.

[0074] According to the above-described arrangement, it is possible to more effectively increase the component of the current flowing in the direction perpendicular to the substrate 110.

[0075] <<1.3.Effects>> Next, the effects achieved by the antenna device 10 according to this embodiment will be described in detail.

[0076] 4 and 5 are diagrams for explaining the effects achieved by the antenna device 10 including the metal element 130 according to this embodiment.

[0077] FIG. 4 shows a graph illustrating the directivity of H polarized waves and V polarized waves by an antenna device (hereinafter referred to as a comparison device) that includes a chip antenna and a metal element that do not satisfy the above-mentioned arrangement conditions.

[0078] Referring to Figure 4, in the comparative device, the V-polarized wave component is relatively smaller than the H-polarized wave component in all directions around the substrate (each direction on the horizontal plane defined by the X-axis and Y-axis), and in particular, the V-polarized wave component in the Y-axis direction is significantly smaller.

[0079] Meanwhile, FIG. 5 shows a graph illustrating the directivity of H polarized waves and V polarized waves by the antenna device 10 including the chip antenna 120 and the metal element 130 that satisfy the above-described arrangement conditions according to this embodiment.

[0080] Referring to Figure 5, it can be seen that in the antenna device 10 of this embodiment, the V-polarized wave component is generally increased in all directions around the substrate 110 (in each direction on the horizontal plane defined by the X-axis and Y-axis) compared to the comparison device.

[0081] As described above, the antenna device 10 equipped with the metal element 130 according to this embodiment has a simple configuration that uses a battery or the like that is originally provided in a portable device as the metal element 130, and it is possible to form a substantially uniform signal directivity in all directions around the surface of the substrate 110, even in cases where the internal space is limited, such as in a portable device.

[0082] Furthermore, even if H polarization is susceptible to the influence of the human body as described above, it is possible to establish wireless communication using V polarization, which is less susceptible to the influence of the human body.

[0083] <2. Supplementary Information> Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0084] 10: Antenna device, 110: Substrate, 120: Chip antenna, 130: Metal element

Claims

1. a chip antenna disposed on the substrate; a metal element disposed above or below the chip antenna in a direction perpendicular to the plane of the substrate; Equipped with The metal element is a battery that supplies power to the chip antenna. Antenna device.

2. The metal element is arranged so that the distance between the metal element and the chip antenna is shorter than a specified length determined according to the frequency of a signal transmitted by the chip antenna. The antenna device according to claim 1 .

3. The metal element is arranged so that the distance between the metal element and the chip antenna is shorter than a quarter of the wavelength of the frequency of the signal transmitted by the chip antenna. The antenna device according to claim 2 .

4. The metal element is formed so that its thickness in a direction perpendicular to the plane of the substrate satisfies a specified condition determined by the frequency of a signal transmitted by the chip antenna. The antenna device according to claim 1 .

5. The metal element is formed so that the thickness in a direction perpendicular to the plane of the substrate is equal to or less than the wavelength of the frequency of the signal transmitted by the chip antenna.

5. The antenna device according to claim 4.

6. It is installed in a portable device carried by a user. The antenna device according to claim 1 .

7. The chip antenna transmits an ultra-wideband signal. The antenna device according to any one of claims 1 to 6.

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