Antenna equipment

Abstract

The present invention provides an antenna device that widens the directivity of radio wave radiation while suppressing its size, and that can secure a grounding path when mounted on a circuit board while considering the maintenance of that directivity. [Solution] An antenna device comprising a rectangular prism-shaped recess defined by a bottom surface on which a radiating element is arranged and four sides surrounding the radiating element when viewed from a direction perpendicular to the bottom surface, a ground layer arranged on the back side of the bottom surface, an element surrounding portion made of dielectric material, and a power supply portion that connects to the radiating element and supplies power to the radiating element at a position offset from the center of the radiating element along the direction in which the sides face each other when viewed from a direction perpendicular to the radiating element, and a flat metal portion provided on the outer edge of the ground layer along the thickness direction of the ground layer.

Description

Technical Field

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

Background Art

[0002] An antenna device is required to have a wide-angle radiation directivity capable of transmitting and receiving radio waves in various directions. For example, Patent Document 1 discloses a technique for obtaining a wide-angle radiation directivity by performing beamforming by giving a phase difference to each antenna in an array antenna in which a plurality of antennas are arranged in an array.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, miniaturization has been desired for antenna devices. On the other hand, the array antenna disclosed in Patent Document 1 requires a space for arranging a plurality of antennas, so there is a concern about enlargement. Therefore, there has been a demand for the development of an antenna device that widens the radiation directivity of radio waves while suppressing enlargement. In addition, an antenna device tends to have a lower radiation directivity when mounted on a circuit board than when it is alone, so mounting on a circuit board is considered while maintaining the radiation directivity. At this time, there has also been a demand for the development of an antenna device capable of securing a grounding path while considering the maintenance of the radiation directivity.

[0005] The present invention has been made to solve at least a part of the above-described problems, and an object thereof is to provide an antenna device that widens the radiation directivity of radio waves while suppressing enlargement and can secure a grounding path when mounted on a circuit board while considering the maintenance of the radiation directivity. [Means for solving the problem]

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

[0007] (1) According to one embodiment of the present invention, an antenna device is provided. This antenna device has a rectangular prism-shaped recess defined by a bottom surface on which a radiating element is arranged and four side surfaces that surround the radiating element when viewed from a direction perpendicular to the bottom surface, and a ground layer is arranged on the surface opposite to the bottom surface, and comprises an element surrounding portion made of a dielectric material and a power supply portion that is 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 when viewed from the direction perpendicular to the bottom surface, and supplies power to the radiating element, and the outer edge of the ground layer is provided with a metallic flat portion along the thickness direction of the ground layer.

[0008] With this configuration, when viewed from a perpendicular direction, the radiating element is surrounded by four sides that define the recessed portion of the element enclosure made of dielectric material. Therefore, the electromagnetic distribution of these sides made of dielectric material can widen the radiation directivity of the radio waves emitted from the radiating element. Furthermore, since it is not necessary to arrange multiple antennas to widen the angle, the size of the antenna device itself can be kept down. The inventors of this application have also found that when the antenna device is mounted on a circuit board with the opening of the recessed portion of the antenna device facing in the direction of the circuit board, the antenna device can be mounted on the circuit board while maintaining the same radiation directivity as when the antenna device is used alone. In this regard, with this configuration, a flat portion is provided on the outer edge of the ground layer along the thickness direction of the ground layer. Therefore, when the antenna device is mounted on a circuit board while considering the maintenance of radiation directivity, this flat portion can be brought into contact with the ground conductor on the circuit board. In other words, a grounding path from the antenna device to the circuit board can be secured. Therefore, this configuration makes it possible to provide an antenna device that widens the directivity of radio wave radiation while suppressing an increase in size, and that can secure a grounding path when mounted on a circuit board while considering the maintenance of that directivity.

[0009] (2) In the antenna device according to the above embodiment, the planar portion may be a plating layer that covers the outer edge of the ground layer. With this configuration, a grounding path from the antenna device to the circuit board can be secured by bringing the plated layer, which is a flat surface, into contact with the ground conductor on the circuit board.

[0010] (3) In the antenna device according to the above embodiment, a recess is formed on the outer edge of the ground layer, and the flat portion may be the side surface of a columnar metal member filling the recess. With this configuration, a grounding path from the antenna device to the circuit board can be secured by bringing the side surface of the columnar metal member, which is a flat surface, into contact with the ground conductor on the circuit board.

[0011] (4) In the antenna device according to the above embodiment, the end of the power supply section opposite to the end connected to the radiating element and the planar portion may be arranged on the outer edge of the ground layer in the direction from the center toward the position. With this configuration, the end of the feed section opposite to the end connected to the radiating element, and the planar section, are positioned on the same outer edge of the ground layer. This allows for simultaneous contact between the ground conductor on the circuit board and the planar section, and between the feed line on the circuit board (which is the source of the high-frequency signal supplied to the feed section) and the end, while maintaining radiation directivity when the antenna device is mounted on the circuit board. In other words, it is possible to simultaneously secure a grounding path from the antenna device to the circuit board and secure a high-frequency signal source at the feed section. Furthermore, this configuration allows for a shorter distance between one end and the other at the feed section. As a result, high-frequency signals can be supplied to the radiating element more efficiently.

[0012] Furthermore, the present invention can be realized in various forms, for example, as an antenna device, a communication device, or a component or device comprising these. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view of the antenna device according to the first embodiment. [Figure 2] This is a magnified view of the area around the notch. [Figure 3] This is an explanatory diagram of a circuit board. [Figure 4] This is an explanatory diagram showing the antenna device mounted on a circuit board. [Figure 5] This is an explanatory diagram showing the antenna device of the second embodiment. [Figure 6] This is a magnified view showing the area around the edge. [Modes for carrying out the invention]

[0014] <First Embodiment> Figure 1 is a perspective view of an antenna device 1 according to a first embodiment of the present invention. Figure 1 shows mutually orthogonal XYZ axes. These XYZ axes are common to Figures 1 to 6. The antenna device 1 comprises an element surrounding section 10 and a power supply section 20.

[0015] The element enclosure 10 is made of a dielectric material. The element enclosure 10 has a rectangular prism-shaped recess D in the central part when viewed from the +Z axis direction. The recess D is defined by a bottom surface B and four sides S1 to S4. A rectangular radiating element R is placed in the central part on the bottom surface B. The radiating element R is an element that radiates radio waves in the +Z axis direction when a high-frequency signal is supplied from a power supply unit 20, which will be described later. The sides S1 to S4 surround the radiating element R when viewed from an orthogonal direction perpendicular to the bottom surface B (in this embodiment, the +Z axis direction). Sides S1 and S2 are sides along the YZ plane and are opposite to each other. Sides S3 and S4 are sides along the XZ plane and are opposite to each other.

[0016] Furthermore, three ground layers G1 to G3 are arranged on the back side of the bottom surface B of the element surrounding portion 10. The ground layers G1 to G3 are arranged in the order of ground layer G1, ground layer G2, and ground layer G3 from the +Z axis side. As shown in Figure 1, each of the ground layers G1 to G3 is a plate-shaped metal member with a larger area than the bottom surface B. The ground layers G1 to G3 are stacked alternately with dielectric layers D1 and D2 (shown in Figure 4), and are electrically connected to each other via multiple vias (not shown) that penetrate the dielectric layers D1 and D2. Hereafter, the ground layers G1 to G3 will be collectively referred to as the ground layer G. Since the ground layers G 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.

[0017] On the outer edge of the ground layer G on the -X axis direction side, a plating layer PL covering the outer edge of the ground layer G is provided. Specifically, the plating layer PL is along the YZ plane and covers a portion closer to the center excluding the end sides in the +Y axis direction and -Y axis direction of the outer edge. The plating layer PL corresponds to a planar portion F made of metal along the thickness direction of the ground layer G (the Z axis direction in this embodiment). A notch Nt is provided at the central position of the plating layer PL in the Y axis direction. Details of the notch Nt will be described later using FIG. 2.

[0018] As shown in FIG. 1, a feeding portion 20 is connected to the radiation element R. One end portion 21 of the feeding portion 20 can be regarded as the connection position between the radiation element R and the feeding portion 20. The feeding portion 20 is connected to the radiation element R and feeds power to the radiation element R at a position shifted along the direction (the X axis direction in this embodiment) where the side surfaces S1 and S2 face each other from the center O of the radiation element R as viewed from the orthogonal direction (the +Z axis direction in this embodiment). Specifically, the feeding portion 20 is connected to the radiation element R at a position shifted -X axis direction from the center O of the radiation element R as viewed from the orthogonal direction.

[0019] FIG. 2 is an enlarged view of the periphery of the notch Nt. As described in FIG. 1, a part of the outer edge of the ground layer G is covered by the plating layer PL. On the other hand, at the position where the notch Nt is provided in the plating layer PL, at least the ground layers G2 and G3 are exposed outside the antenna device 1 as shown in FIG. 2. The end portion 22 on the side opposite to the end portion 21 of the feeding portion 20 connected to the radiation element R is arranged on the side (the -X axis direction in this embodiment) in the direction from the center O to the position of the end portion 21 (the connection position between the radiation element R and the feeding portion 20) of the outer edge of the ground layer G. The end portion 22 is formed in a planar shape along the YZ plane. The feeding portion 20 extends from the end portion 21 (see FIG. 1) connected to the radiation element R to the end portion 22 (see FIG. 2) exposed outside the antenna device 1. Further, such an end portion 22 and the plating layer PL which is the planar portion F are arranged on the outer edge on the same -X axis direction side of the outer edge of the ground layer G.

[0020] FIG. 3 is an explanatory diagram of the circuit board 2. FIG. 4 is an explanatory diagram showing a state where the antenna device 1 is mounted on the circuit board 2. The circuit board 2 is a plate-like member extending along the YZ plane. The circuit board 2 is a substrate on which the antenna device 1 described in FIG. 1 is mounted and on which circuit components (not shown) forming a high-frequency circuit for processing high-frequency signals transmitted and received by the antenna device 1 are mounted. As the circuit board 2, for example, a PCB substrate such as a glass epoxy substrate can be used. As shown in FIGS. 3 and 4, the circuit board 2 includes a ground conductor GC1, a base material BS, and a ground conductor GC2. The base material BS is a plate-like member formed of a dielectric material. The ground conductor GC1 and the power supply line PS are disposed on the surface of the base material BS on the side in the +X-axis direction. Further, a plurality of vias vs are arranged along the power supply line PS. On the other hand, the ground conductor GC2 is disposed on the surface of the base material BS on the side in the -X-axis direction. As shown in FIG. 4, the general view of the circuit board 2 is a laminate in which a ground layer G1, the base material BS, and a ground layer G3 are arranged in order from the side in the +X-axis direction. The region NL shown in FIGS. 3 and 4 is a region of the ground conductor GC1 that does not overlap with the ground conductor GC2 when the circuit board 2 is viewed through from the side in the +X-axis direction.

[0021] As shown in FIG. 4, the inventors of the present application found that when the antenna device 1 is mounted on the circuit board 2 with the opening OP (shown in FIG. 4) of the recess D of the antenna device 1 directed in the direction along the circuit board 2 (the +Z-axis direction in FIG. 4), the antenna device 1 can be mounted on the circuit board 2 while maintaining the same radiation directivity as that of the antenna device 1 alone. Here, the antenna device 1 alone refers to the antenna device 1 in a single state not mounted on the circuit board 2. In the state shown in FIG. 4, the plating layer PL in the antenna device 1 and the region NL in the circuit board 2 are in contact with each other. Therefore, a grounding path from the antenna device 1 to the circuit board 2 is ensured. Further, in the state shown in FIG. 4, the end portion 22 of the power supply unit 20 and the power supply line PS disposed on the circuit board 2 are connected. Therefore, a supply source for supplying a high-frequency signal to the power supply unit 20 is ensured.

[0022] According to the antenna device 1 of the first embodiment described above, the radiating element R is surrounded by four side surfaces S1 to S4 that define the recessed portion D of the element surrounding portion 10, which is made of dielectric material, when viewed from an orthogonal direction (in this embodiment, the +Z axis direction). Therefore, the electromagnetic distribution of the side surfaces S1 to S4 made of dielectric material can be used to widen the radiation directivity of the radio waves radiated from the radiating element R. Furthermore, according to the antenna device 1 of the first embodiment, it is not necessary to arrange multiple antennas to widen the angle, so the antenna device 1 itself can be kept from becoming larger.

[0023] Furthermore, as described above, the inventors of the present invention have found that when the antenna device 1 is mounted on the circuit board 2 with the opening OP of the recessed portion D of the antenna device 1 oriented in a direction along the circuit board 2, the antenna device 1 can be mounted on the circuit board 2 while maintaining the same radiation directivity as when the antenna device 1 is used alone. In this regard, according to the antenna device 1 of the first embodiment, a plating layer PL is provided as a planar portion F along the thickness direction of the ground layer G on the outer edge of the ground layer G. Therefore, when the antenna device 1 is mounted on the circuit board 2 while considering the maintenance of radiation directivity (the state in Figure 4), this plating layer PL can be brought into contact with the ground conductor GC1 on the circuit board 2. In other words, a grounding path from the antenna device 1 to the circuit board 2 can be secured. Accordingly, the antenna device 1 of the first embodiment is configured to widen the radiation directivity of radio waves while suppressing an increase in size, and to secure a grounding path when mounted on the circuit board 2 while considering the maintenance of that radiation directivity.

[0024] Furthermore, in the antenna device 1 of the first embodiment, the plated layer PL, which is the planar portion F, and the end portion 22 of the feed portion 20 are located on the same outer edge of the outer edge of the ground layer G (in this embodiment, the side in the -X axis direction). Therefore, in a state where the antenna device 1 is mounted on the circuit board 2 while considering the maintenance of radiation directivity (as shown in Figure 4), contact between the ground conductor GC1 on the circuit board 2 and the planar portion F, and contact between the feed line PS on the circuit board 2, which is the source for supplying high-frequency signals to the feed portion 20, and the end portion 22 can be achieved simultaneously. In other words, securing a grounding path from the antenna device 1 to the circuit board 2 and securing a source for supplying high-frequency signals in the feed portion 20 can be achieved simultaneously. In addition, in the antenna device 1 of the first embodiment, the length between one end portion 21 and the other end portion 22 of the feed portion 20 can be shortened. As a result, high-frequency signals can be supplied to the radiating element R efficiently.

[0025] <Second Embodiment> Figure 5 is an explanatory diagram showing an antenna device 1a of a second embodiment of the present invention. The antenna device 1a of the second embodiment differs from the antenna device 1 of the first embodiment (see Figures 1 and 2) mainly in that the side surface SD of the metal member MP corresponds to the flat surface F instead of the plating layer PL.

[0026] As shown in Figure 5, in the antenna device 1a of the second embodiment, the plating layer PL is not provided on the outer edge of the ground layer G on the side in the -X axis direction. That is, the outer edge of the ground layer G on the side in the -X axis direction is exposed to the outside of the antenna device 1. Furthermore, a plurality of metal members MP are provided on this outer edge. In addition, the end portion 22a of the feed section 20 is provided at the central position in the Y axis direction of this outer edge.

[0027] Figure 6 is an enlarged view of the area around end 22a. A recess RS1 is formed on the outer edge of the ground layer G1. In Figure 6, similar recesses RS2 and RS3 are also formed on the outer edges of the ground layers G2 and G3. The metal member MP is a columnar member that fills the recesses formed in each of the ground layers G. In this embodiment, the metal member MP is a columnar member with a substantially semicircular surface as its base.

[0028] In Figure 6, the side surface SD of the metal member MP, indicated by hatching, is a surface aligned with the YZ plane. In the antenna device 1a of the second embodiment, the side surface SD corresponds to a flat metal portion F aligned with the thickness direction of the ground layer G (in this embodiment, the Z-axis direction). Furthermore, the side surface SD, which is the flat portion F, and the end portion 22a are located on the outer edge of the ground layer G on the same -X-axis side, similar to the first embodiment.

[0029] The antenna device 1a of the second embodiment is mounted on the circuit board 2 in the same manner as the antenna device 1 of the first embodiment, as shown in Figure 4. At this time, a grounding path from the antenna device 1a to the circuit board 2 is secured by the contact between multiple side surfaces SD and regions NL on the circuit board 2. In addition, a power source for supplying high-frequency signals to the power supply unit 20 is secured by the connection between the end 22a of the power supply unit 20 and the power supply line PS arranged on the circuit board 2.

[0030] In the antenna device 1a of the second embodiment described above, similar to the antenna device 1 of the first embodiment, the radio wave radiation directivity is widened while suppressing an increase in size, and the device is configured to ensure a grounding path when mounted on the circuit board 2 while considering the maintenance of that radiation directivity. In the antenna device 1a of the second embodiment, since the planar portion F is the side surface SD of the columnar metal member MP, a grounding path from the antenna device 1 to the circuit board 2 can be secured by bringing the side surface SD into contact with the ground conductor GC1 on the circuit board 2.

[0031] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0032] In the first and second embodiments described above, the radiating element R was rectangular in shape, but it may be any shape, such as a circle or a polygon.

[0033] In the first and second embodiments described above, the ends 22 and 22a were positioned on the outer edge of the ground layer G in the direction from the center O toward the end 21 (in this embodiment, the -X axis direction), but are not limited to this. The ends 22 and 22a may be positioned on any side of the outer edge of the ground layer G. Of course, if the length between one end 21 and the other end 22 and 22a is to be shortened, it is preferable to position the ends 22 and 22a on the outer edge of the ground layer G in the direction from the center O toward the end 21.

[0034] In the first and second embodiments described above, the antenna devices 1 and 1a were mounted on the circuit board 2 such that the planar portion F (plating layer PL or multiple side surfaces SD) and the region NL on the circuit board 2 were in contact, but the invention is not limited to this. As long as the planar portion F is in contact with the ground conductor GC1, the antenna devices 1 and 1a may be mounted at any position on the circuit board 2.

[0035] In the second embodiment described above, the metal member MP was a columnar member with a substantially semicircular surface as its base, but it is not limited to this. The metal member MP may be a columnar member with a base of any shape as long as it has a side surface SD along the thickness direction of the ground layer G. The shapes of the recesses RS1 to RS3 are adjusted according to the cross-sectional shape of the metal member MP (the cross-sectional shape when cut in the XY plane). In other words, the shapes of the recesses RS1 to RS3 may be any shape as long as the metal member MP can fill the recesses RS1 to RS3. Furthermore, if the cross-sectional shape of the metal member MP is not constant depending on its position in the Z-axis direction, the shapes of the recesses RS1 to RS3 may be different from each other.

[0036] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate. [Explanation of Symbols]

[0037] 1,1a…Antenna equipment 2…Circuit board 10... Elements surrounding area 20... Power supply section 21…End 22,22a...end B…Bottom surface BS…Base material D... recessed area F...Plane part G1~G3...Grand Layer GC1, GC2... Ground conductors MP... Metal component NL…Area Nt... Notch O…center OP...Opening PL...plating layer PS...Power supply line R... Radiation RS1, RS2, RS3... recessed S1~S4…side SD…side vs... Beer

Claims

1. An antenna device, The device has a rectangular prism-shaped recess defined by a bottom surface on which a radiating element is placed, and four sides surrounding the radiating element when viewed from a direction perpendicular to the bottom surface, with a ground layer placed on the back side of the bottom surface and an element surrounding portion formed of a dielectric material. The system comprises a power supply unit connected to the radiating element at a position offset from the center of the radiating element along the direction in which the side surface faces the radiating element, when viewed from the orthogonal direction, and for supplying power to the radiating element, An antenna device characterized in that a flat metal portion is provided on the outer edge of the ground layer, along the thickness direction of the ground layer.

2. The antenna device according to claim 1, The antenna device is characterized in that the planar portion is a plating layer covering the outer edge of the ground layer.

3. The antenna device according to claim 1, A recess is formed on the outer edge of the ground layer. The antenna device is characterized in that the flat portion is the side surface of a columnar metal member that fills the recess.

4. An antenna device according to any one of claims 1 to 3, An antenna device characterized in that the end of the power supply section opposite to the end connected to the radiating element and the planar portion are arranged on the outer edge of the ground layer in the direction from the center toward the position.

Images