Antenna device

Abstract

To provide an antenna device which widens an angle of radiation directivity of a radio wave while suppressing an increase in size, and improves a gain of the radio wave in an orthogonal direction.SOLUTION: An antenna device includes an element surrounding portion made of a dielectric material and including a quadrangular prism-shaped recessed portion defined by a bottom surface on which a radiating element is disposed and four side surfaces surrounding the radiating element when viewed in a direction orthogonal to the bottom surface, and a ground layer disposed on a side opposite to the bottom surface. And a power supply unit that supplies power to the radiating element, wherein at least a part of each of two side surfaces facing each other along a deviation direction from the center to the position among the side surfaces is covered with a metal layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Antenna devices are required to have a wide-angle radiation directivity that can transmit and receive radio waves in various directions. For example, Patent Document 1 discloses a technology in which an array antenna, in which multiple antennas are arranged in an array, performs beamforming by giving each antenna a phase difference, thereby achieving a wide-angle radiation directivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6818757 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for smaller antenna devices. On the other hand, the array antenna disclosed in Patent Document 1 requires space to accommodate multiple antennas, which raises concerns about its large size. Therefore, there has been a demand for the development of an antenna device that widens the radiation directivity of radio waves while suppressing its size. There has also been a demand for such an antenna device to achieve both a wide radiation directivity angle and improved radio wave gain.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide an antenna device that widens the radiation directionality of radio waves while suppressing an increase in size, and also improves the gain of radio waves in orthogonal directions. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided an antenna device, comprising: an element enclosing section having a rectangular prism-shaped recess defined by a bottom surface on which a radiating element is disposed and four side surfaces surrounding the radiating element as viewed in a direction perpendicular to the bottom surface, with a ground layer disposed on the reverse side of the bottom surface and formed of a dielectric material; and a power supply section connected to the radiating element at a position offset from the center of the radiating element along the direction in which the side surfaces face each other as viewed in the perpendicular direction, and supplying power to the radiating element, wherein at least a portion of each of two of the side surfaces facing each other along the direction in which the side surfaces face each other from the center is covered with a metal layer.

[0008] According to this configuration, when viewed from the orthogonal direction, the radiating element is surrounded by four side surfaces of the element enclosure formed of a dielectric material that define the recessed portion. Therefore, the electromagnetic distribution of the side surfaces formed of a dielectric material can widen the radiation directivity of the radio waves radiated from the radiating element. Furthermore, since it is not necessary to arrange multiple antennas to widen the radiation angle, the antenna device itself can be prevented from becoming large. Furthermore, the inventors of the present application discovered that when at least a portion of each of the two side surfaces facing each other along the offset direction is covered with a metal layer, the gain of the radio waves in the orthogonal direction is improved. Therefore, according to this configuration, the gain of the radio waves in the orthogonal direction can also be improved. Therefore, according to this configuration, it is possible to provide an antenna device that widens the radiation directivity of the radio waves and improves the gain of the radio waves in the orthogonal direction while preventing the device from becoming large.

[0009] (2) In the antenna device of the above aspect, two of the side surfaces that are different from the two side surfaces that face each other along the shift direction may not be covered with a metal layer. The inventors of the present application have found that when two of the side surfaces that face each other along the shift direction are at least partially covered with a metal layer, and when two other side surfaces that face each other along the shift direction are not covered with a metal layer, the gain of the radio waves in the orthogonal direction is further improved. Therefore, with this configuration, the gain of the radio waves in the orthogonal direction can be further improved.

[0010] (3) In the antenna device according to the above aspect, the entire surface of each of the two side surfaces that face each other along the shift direction may be covered with a metal layer. The inventors of the present application have found that the gain of radio waves in the orthogonal direction is further improved when the entire surfaces of the two side surfaces facing each other along the offset direction are covered with a metal layer, compared to when only a portion of each of the two side surfaces is covered with a metal layer. Therefore, this configuration can further improve the gain of radio waves in the orthogonal direction.

[0011] The present invention can be realized in various forms, for example, in the form of an antenna device, a communication device, or a component or device including these. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of an antenna device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the antenna device. [Figure 3] FIG. 2 is a cross-sectional view of the antenna device. [Figure 4] FIG. 2 is an explanatory diagram of radiation directivity of the antenna device. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Embodiment> Fig. 1 is a perspective view of an antenna device 1 according to an embodiment of the present invention. Fig. 2 is a plan view of the antenna device 1. Fig. 3 is a cross-sectional view of the antenna device 1 taken along line F3-F3 in Fig. 2. Each of Figs. 1 to 3 illustrates mutually orthogonal X, Y and Z axes. The antenna device 1 includes an element enclosure 10 and a power feed section 20.

[0014] The element enclosing portion 10 is made of a dielectric material. The element enclosing portion 10 has a rectangular parallelepiped shape as a whole, with a rectangular prism-shaped recessed portion D in the center when viewed from the +Z-axis direction. The recessed portion D is defined by a bottom surface B and four side surfaces S1 to S4. A rectangular radiating element R is disposed in the center on the bottom surface B. The radiating element R is an element that radiates radio waves toward the +Z-axis direction when a high-frequency signal is fed from a power feeding portion 20, which will be described later. The side surfaces S1 to S4 surround the radiating element R when viewed from a direction perpendicular to the bottom surface B (the +Z-axis direction in this embodiment) (see FIG. 2). The side surfaces S1 and S2 are side surfaces that extend along the YZ plane and face each other. The side surfaces S3 and S4 are side surfaces that extend along the XZ plane and face each other. The hatching on the side surfaces S1 and S2 in FIG. 1 will be described later.

[0015] 3, three ground layers G1 to G3 are arranged on the back surface b side of the bottom surface B of the element enclosure 10. The ground layers G1 to G3 are arranged in the order of G1, G2, and G3 from the +Z-axis direction. As shown in FIGS. 1 and 3, each of the ground layers G1 to G3 is a plate-shaped metal member having an area equivalent to that of the back surface b. The ground layers G1 to G3 are alternately stacked with dielectric layers D1 and D2 and are electrically connected to each other through a plurality of vias V that penetrate the dielectric layers D1 and D2. Since the ground layers G1 to G3 and the radiating element R are arranged opposite each other, the ground of the antenna device 1 is strengthened, which is effective in improving the antenna characteristics.

[0016] 3, a feed via hole functioning as the feed section 20 is connected to the radiating element R. An end 20e of the feed section 20 can be regarded as the connection position between the radiating element R and the feed section 20. As shown in FIGS. 1 and 2, the feed section 20 is connected to the radiating element R at a position offset from the center O of the radiating element R in the direction in which the side surfaces S1 and S2 face each other (in the X-axis direction in this embodiment) when viewed from the orthogonal direction, and feeds power to the radiating element R. More specifically, the feed section 20 is connected to the radiating element R at a position offset from the center O of the radiating element R in the -X-axis direction when viewed from the orthogonal direction. Hereinafter, the direction from the center O of the radiating element R to the connection position (end 20e) of the feed section 20 (in the X-axis direction in this embodiment) may be referred to as the offset direction.

[0017] Of the side surfaces S1 to S4, at least a portion of each of the two side surfaces S1 and S2 that face each other along the offset direction is covered with a metal layer. In this embodiment, the entire surface of each of the two side surfaces S1 and S2 is covered with a metal layer. The hatching on the side surfaces S1 and S2 indicates that they are covered with a metal layer.

[0018] On the other hand, the two side surfaces S3, S4, which are different from the two side surfaces S1, S2 that face each other along the offset direction among the side surfaces S1 to S4, are not covered with a metal layer. For this reason, the side surfaces S3, S4 are not hatched in the same manner as the side surfaces S1, S2. Here, the side surfaces S3, S4 that are not covered with a metal layer include not only cases where the entire surface of each of the side surfaces S3, S4 is not completely covered with a metal layer, but also cases where, for example, when processing is performed to cover the side surface S1 or the side surface S2 with a metal layer, the material forming the metal layer overflows from the side surface S1 or the side surface S2 and covers part of the side surface S3 or the side surface S4.

[0019] FIG. 4 is an explanatory diagram of the radiation directivity of the antenna device 1. In FIG. 4, the radiation directivity of the antenna device 1 of this embodiment is shown by a solid line, and the radiation directivity of an antenna device of a comparative example (hereinafter referred to as antenna device 1c) is shown by a dashed line. The radiation directivity shown by the solid line and the dashed line is both radiation directivity in the YZ plane. The antenna device 1c of the comparative example is the same as the antenna device 1 of this embodiment except that none of the side surfaces S1 and S2 are covered with a metal layer. In other words, none of the side surfaces S1 to S4 of the antenna device 1c of the comparative example are covered with a metal layer.

[0020] As shown by the solid and dashed lines in Figure 4, in both antenna device 1 and antenna device 1c, the gain peaked when the radio wave radiation direction was oriented in the +Z-axis direction, and it was confirmed that the radiation directivity of the radio waves was wider in angle. The wider radiation directivity of the radio waves is thought to be due to the fact that radiating element R is surrounded by side surfaces S1 to S4 made of a dielectric material. Furthermore, antenna device 1 had improved gain in the +Z-axis direction compared to antenna device 1c.

[0021] According to the antenna device 1 of the embodiment described above, when viewed from the orthogonal direction (the +Z-axis direction in this embodiment), the radiating element R is surrounded by four side surfaces S1 to S4 that define the recessed portion D of the element enclosing portion 10 formed of a dielectric material. Therefore, the radiation directivity of the radio waves radiated from the radiating element R can be made wider in angle due to the influence of the electromagnetic distribution of the side surfaces S1 to S4 formed of a dielectric material.

[0022] Furthermore, according to the antenna device 1 of the embodiment, it is not necessary to arrange multiple antennas to widen the radiation angle, so that the size of the antenna device 1 itself can be prevented from increasing. Furthermore, the inventors of the present application have found that when at least a portion of each of two side surfaces S1, S2 that face each other along the offset direction among the side surfaces S1 to S4 that define the recessed portion D is covered with a metal layer, the gain of radio waves in a direction perpendicular to the bottom surface B is improved. Therefore, according to the antenna device 1 of the embodiment, the gain of radio waves in the perpendicular direction can also be improved. Therefore, it can be said that the antenna device 1 of the embodiment is an antenna device that widens the radiation directivity of radio waves while preventing an increase in size, and also improves the gain of radio waves in the perpendicular direction.

[0023] Furthermore, in the antenna device 1 of the embodiment, the side surfaces S3 and S4, which are different from the side surfaces S1 and S2 that face each other along the shift direction among the side surfaces S1 to S4, are not covered with a metal layer. The inventors of the present application have found that when at least a portion of each of the side surfaces S1 and S2 that face each other along the shift direction is covered with a metal layer and when each of the side surfaces S3 and S4, which are different from the side surfaces S1 and S2 that face each other along the shift direction, is not covered with a metal layer, the gain of radio waves in the orthogonal direction is further improved. Therefore, in the antenna device 1 of the embodiment, the gain of radio waves in the orthogonal direction is further improved.

[0024] Furthermore, in the antenna device 1 of the embodiment, the entire surface of each of the side surfaces S1 and S2, which are opposed to each other along the offset direction among the side surfaces S1 to S4, is covered with a metal layer. The inventors of the present application have found that the gain of radio waves in the orthogonal direction is further improved when the entire surface of each of the side surfaces S1 and S2 is covered with a metal layer, compared to when only a portion of each of the side surfaces S1 and S2 opposed to each other along the offset direction is covered with a metal layer. Therefore, the antenna device 1 of the embodiment can further improve the gain of radio waves in the orthogonal direction.

[0025] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0026] In the above embodiment, the element surrounding portion 10 may be formed such that the portion surrounding the recessed portion D and the plate-like portion including the bottom surface B and back surface b are integrally formed from the beginning, or may be formed separately and then integrated by bonding (see FIG. 3). Also, in the above embodiment, the element surrounding portion 10 is formed in a rectangular parallelepiped shape as a whole, but the overall shape may be any three-dimensional shape as long as it has a quadrangular prism-shaped recessed portion D in the center when viewed from the +Z-axis direction.

[0027] In the above embodiment, the radiating element R has a rectangular shape, but it may have any shape, such as a circular shape or a polygonal shape.

[0028] In the above description, it was described that, as an embodiment of the present invention, antenna device 1 in which the entire surfaces of each of side surfaces S1 and S2 are covered with a metal layer but side surfaces S3 and S4 are not covered with a metal layer has improved gain in the +Z direction compared to antenna device 1c of the comparative example. However, this is not limited to this. It has been confirmed that even an antenna device in which the entire surfaces of all of side surfaces S1 to S4 are covered with a metal layer has improved gain in the +Z direction compared to antenna device 1c of the comparative example. It has also been confirmed that, compared to a case in which all of side surfaces S1 to S4 are covered with a metal layer, a case in which the entire surfaces of each of side surfaces S1 and S2 are covered with a metal layer but side surfaces S3 and S4 are not covered with a metal layer (i.e., antenna device 1) has improved gain in the +Z direction compared to a case in which all of side surfaces S1 to S4 are covered with a metal layer. Furthermore, from the perspective of improving gain, it is preferable that the entire surfaces of side surfaces S1 to S4 are covered with a metal layer rather than a case in which only a portion of the surfaces is covered with a metal layer.

[0029] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate. [Explanation of symbols]

[0030] 1...Antenna device 10...Element enclosure 20...Power supply unit 20e...end B…Bottom surface D...Depression G1~G3...Ground layer R...Radiating element S1~S4…side V...Beer b…Back side

Claims

1. An antenna device, an element surrounding portion formed of a dielectric material, the element surrounding portion having a rectangular prism-shaped recess defined by a bottom surface on which a radiating element is disposed and four side surfaces surrounding the radiating element as viewed from a direction perpendicular to the bottom surface, the element surrounding portion having a ground layer disposed on the back side of the bottom surface; a power supply section that is connected to the radiating element at a position shifted from the center of the radiating element along the direction in which the side surfaces face each other, when viewed from the orthogonal direction, and that supplies power to the radiating element; An antenna device, wherein at least a portion of each of two of the side surfaces that face each other along the shift direction from the center to the position is covered with a metal layer.

2. 2. The antenna device according to claim 1, An antenna device, wherein two of the side surfaces that are different from the two side surfaces that face each other along the shift direction are not covered with a metal layer.

3. 3. The antenna device according to claim 1, The antenna device, wherein the entire surface of each of two of the side surfaces that face each other along the shift direction is covered with a metal layer.

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