Antenna device

Abstract

Provided is an antenna device including: an antenna that performs at least one of transmission and reception of an electromagnetic wave; and a meta-lens through which the electromagnetic wave is transmitted. The meta-lens includes a plurality of unit cells arranged two-dimensionally. Each of the plurality of unit cells has: a plurality of lens layers arranged so as to overlap in a plan view; and a conductive pattern formed in each of the plurality of lens layers.

Description

Antenna device

[0001] This application claims priority to Japanese Patent Application No. 2023-199295, filed on November 24, 2023, the contents of which are incorporated herein by reference.

[0002] In the field of high-speed wireless communication, an antenna device including an antenna and a dielectric lens has been proposed (see, for example, Patent Document 1). The dielectric lens can adjust the transmission and reception characteristics of electromagnetic waves.

[0003] Japanese Patent Application Publication No. 2006-86808

[0004] The antenna device has room for improvement in terms of the transmission and reception characteristics (for example, EIRP, sensitivity, etc.) of the antenna.

[0005] An object of one embodiment of the present invention is to provide an antenna device capable of improving the transmission and reception characteristics of the antenna.

[0006] An antenna device according to a first aspect of the present invention includes an antenna that transmits and / or receives electromagnetic waves, and a metalens through which the electromagnetic waves pass, wherein the metalens includes a plurality of unit cells arranged two-dimensionally, and each of the plurality of unit cells includes a plurality of lens layers arranged to overlap in a planar view, and a conductive pattern formed on each of the plurality of lens layers.

[0007] According to the first aspect of the present invention, when an electromagnetic wave passes through a metalens, the phase of the RF signal is adjusted according to the shape and arrangement of the pattern. This allows for improved transmission and reception characteristics of the antenna. For example, the equivalent isotropically radiated power (EIRP) and sensitivity of the electromagnetic wave can be improved.

[0008] A second aspect of the present invention is the antenna device according to the first aspect, wherein the pattern includes a main portion and an annular portion surrounding the main portion.

[0009] A third aspect of the present invention is the antenna device according to the second aspect, wherein the outer dimensions of the main portion are determined in accordance with the distance from the antenna to the pattern.

[0010] A fourth aspect of the present invention is the antenna device according to the second or third aspect, wherein the main portion has a shape including a plurality of extension portions extending radially from a center.

[0011] A fifth aspect of the present invention is an antenna device according to any one of the first to fourth aspects, wherein the plurality of unit cells form a plurality of annular cell groups arranged in a ring shape, and the plurality of annular cell groups are arranged in a multiple ring shape.

[0012] A sixth aspect of the present invention is an antenna device in which, in any one of the first to fifth aspects, the lens layer is made of a dielectric substrate and the pattern is formed on one surface of the dielectric substrate.

[0013] One aspect of the present invention provides an antenna device capable of improving the transmission and reception characteristics of the antenna.

[0014] FIG. 1 is a plan view of a metalens of the antenna device according to the first embodiment. FIG. 2 is a cross-sectional view of the antenna device according to the first embodiment. FIG. 3 is a perspective view of a metalens of the antenna device according to the first embodiment. FIG. 4 is a perspective view of a unit cell of the antenna device according to the first embodiment. FIG. 5 is a plan view of a unit cell of the antenna device according to the first embodiment. FIG. 6 is a plan view of a first modified example of the unit cell. FIG. 7 is a cross-sectional view of the antenna device according to the second embodiment. FIG. 8 is a cross-sectional view of the antenna device according to the third embodiment.

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Antenna devices according to embodiments of the present invention will now be described with reference to the accompanying drawings.

[0016] [Antenna Device] (First Embodiment) Fig. 1 is a plan view of a metalens 20 of an antenna device 100 according to a first embodiment. Fig. 2 is a cross-sectional view of the antenna device 100. Fig. 3 is a perspective view of the metalens 20. Fig. 4 is a perspective view of a unit cell 21. Fig. 5 is a plan view of the unit cell 21.

[0017] In the following description, the X and Y directions are parallel to the first main surface 10a (front surface) of the antenna 10 (see Figure 2). The X and Y directions are perpendicular to each other. A plane along the X and Y directions is called the XY plane. The Z direction is perpendicular to the X and Y directions. A planar view is a view in the Z direction. +Z is one direction in the Z direction. The +Z side is the front side. The +Z side is the right side in Figure 2. -Z is the direction opposite to +Z.

[0018] As shown in FIG. 2 , the antenna device 100 includes an antenna 10, a metalens 20, a main body 30, and an exterior body 40. The antenna 10 transmits and receives electromagnetic waves. "Transmits and receives" means performing at least one of transmission and reception. The antenna 10 has a flat plate shape. The antenna 10 is provided on a first main surface 30a (front surface) of the main body 30. The main body 30 has, for example, an IC (not shown) that supplies an RF signal. The first main surface 30a of the main body 30 is parallel to the XY plane.

[0019] The exterior body 40 includes a bottom plate 41, a front plate 42, a rear plate 43, a top plate 44, and two side plates (not shown). The front plate 42 is erected from the front end of the bottom plate 41. The rear plate 43 is erected from the rear end of the bottom plate 41. The top plate 44 is formed from the top end of the front plate 42 to the top end of the rear plate 43. A storage space 40a is formed between the front plate 42 and the rear plate 43. The exterior body 40 accommodates the antenna 10 and the main body 30 in the storage space 40a. The side plates are provided on the front and rear sides of the storage space 40a in FIG. 2 .

[0020] The front plate 42 is parallel to the XY plane. The front plate 42 is located at a distance forward from the first main surface 30a of the main body 30. An opening 45 is formed in a position including the center of the front plate 42. The opening 45 is formed to penetrate the front plate 42 in the thickness direction. The exterior body 40 is formed from, for example, liquid crystal polymer (LCP), glass epoxy, polyphenylene ether (PPE) resin, polyimide (PI) resin, or the like.

[0021] The metalens 20 is fitted into the opening 45 in the front plate 42. The metalens 20 is parallel to the XY plane. The metalens 20 is located in front of and spaced apart from the antenna 10 and the first major surface 30a.

[0022] 1 and 3 , the metalens 20 has a rectangular plate shape (e.g., a square shape) with two sides along the X direction and two sides along the Y direction. The metalens 20 includes a plurality of unit cells 21. The plurality of unit cells 21 are arranged two-dimensionally along the XY plane. More specifically, the plurality of unit cells 21 are arranged in a rectangular lattice shape (matrix shape) aligned in the X direction and the Y direction.

[0023] 1 , the metalens 20 is composed of a total of 121 unit cells 21, with 11 aligned in the X direction and 11 aligned in the Y direction. That is, the metalens 20 is composed of unit cells 21 arranged in a rectangular lattice shape (matrix shape) of 11 rows and 11 columns. The multiple unit cells 21 are arranged without any gaps along the XY plane.

[0024] The size of the metalens 20 is determined, for example, so as to encompass the antenna 10 in a plan view (see FIG. 2 ). The X-direction dimension of the metalens 20 is desirably larger than the X-direction dimension of the antenna 10. The Y-direction dimension of the metalens 20 is desirably larger than the Y-direction dimension of the antenna 10.

[0025] As shown in Fig. 4, each of the plurality of unit cells 21 has a plurality of lens layers 22 and conductive patterns 23 formed on the lens layers 22. The lens layers 22 are dielectric substrates formed of a dielectric material. Examples of dielectric materials that constitute the lens layers 22 include liquid crystal polymer (LCP), glass epoxy, polyphenylene ether (PPE) resin, and polyimide (PI) resin. The lens layers 22 are rectangular plate-shaped (e.g., square-shaped) having two sides along the X direction and two sides along the Y direction.

[0026] In the example shown in Fig. 4, one unit cell 21 includes two lens layers 22. Both of the two lens layers 22 are parallel to the XY plane. The two lens layers 22 are arranged with a gap between them in the thickness direction (Z direction). The two lens layers 22 have, for example, the same shape. The two lens layers 22 are arranged so that at least a portion of them overlap in a planar view. It is desirable that the two lens layers 22 are arranged so that the entire regions of them overlap in a planar view.

[0027] Of the two lens layers 22, the lens layer 22 located in the front is a first lens layer 22A. Of the two lens layers 22, the lens layer 22 located in the rear is a second lens layer 22B.

[0028] The pattern 23 is formed on each of the two lens layers 22. For example, the pattern 23 is formed on one surface of the lens layer 22. In the example shown in Fig. 4, the pattern 23 is formed on the front surface 22Aa of the first lens layer 22A and the rear surface 22Bb of the second lens layer 22B.

[0029] The pattern 23 is formed of a conductive material such as a metal. Examples of the metal that constitutes the pattern 23 include copper, silver, gold, and alloys thereof. The pattern 23 can be formed by, for example, an additive method, a subtractive method, or the like.

[0030] As shown in FIG. 5 , the pattern 23 includes a main portion 24 and an annular portion 25. The main portion 24 has a shape with multiple extension portions 26 extending radially from the center. In the example shown in FIG. 5 , the main portion 24 has four extension portions 26. The extension portions 26 are, for example, rectangular in shape extending in the length direction. The four extension portions 26 extend from the center of the lens layer 22 to the −X side, +X side, −Y side, and +Y side, respectively. The main portion 24 has a cross shape as a whole. The four extension portions 26 have the same length. The outer dimension L1 of the main portion 24 is the total length of two extension portions 26 extending in opposite directions. The main portion 24 has a shape with four-fold symmetry (90° symmetry) with the center of the main portion 24 as the axis.

[0031] The annular portion 25 has an annular shape surrounding the main portion 24. The annular portion 25 has, for example, a circular ring shape. The inner diameter of the annular portion 25 is larger than the outer dimension L1 of the main portion 24. The annular portion 25 is formed with a gap between it and the main portion 24. The annular portion 25 is concentric with the main portion 24. The annular portion 25 is formed, for example, inside the outer edge of the lens layer 22. The outer diameter of the annular portion 25 is, for example, smaller than the dimensions of the lens layer 22 in the X direction and the Y direction.

[0032] 4, the pattern 23 formed on the first lens layer 22A is a first pattern 23A. The pattern 23 formed on the second lens layer 22B is a second pattern 23B. The first pattern 23A and the second pattern 23B have the same shape. The first pattern 23A and the second pattern 23B are positioned to overlap in a plan view.

[0033] 1 , the plurality of unit cells 21 form a plurality of annular cell groups 27. The annular cell group 27 is formed by a plurality of unit cells 21 arranged in a rectangular ring shape. The plurality of unit cells 21 includes a unit cell 21A located at the center of the metalens 20, a first annular cell group 27A, a second annular cell group 27B, a third annular cell group 27C, a fourth annular cell group 27D, and a fifth annular cell group 27E.

[0034] The multiple annular cell groups 27 (27A to 27E) are arranged in a multiple annular configuration. Specifically, the first annular cell group 27A is formed by multiple unit cells 21 arranged in a rectangular annular configuration to surround the unit cell 21A. The second annular cell group 27B is formed by multiple unit cells 21 arranged in a rectangular annular configuration to surround the first annular cell group 27A. The third annular cell group 27C is formed by multiple unit cells 21 arranged in a rectangular annular configuration to surround the second annular cell group 27B. The fourth annular cell group 27D is formed by multiple unit cells 21 arranged in a rectangular annular configuration to surround the third annular cell group 27C. The fifth annular cell group 27E is formed by multiple unit cells 21 arranged in a rectangular annular configuration to surround the fourth annular cell group 27D.

[0035] As shown in Figure 5, the outer dimension L1 of the main portion 24 of the pattern 23 is determined in accordance with the distance from the antenna 10 (see Figure 2) to the pattern 23. For example, the outer dimension L1 is determined based on the distance from the antenna 10 to the pattern 23 and the phase of the RF signal of the electromagnetic wave adjusted by the metalens 20. Furthermore, as shown in Figure 1, the patterns 23 in the multiple unit cells 21 are arranged so as to have four-fold symmetry (90-degree symmetry) around the center of the metalens 20.

[0036] The antenna 10 transmits and / or receives electromagnetic waves. For example, the antenna 10 receives an RF signal supplied from an IC (not shown) and transmits the electromagnetic waves. For example, the antenna 10 receives the electromagnetic waves.

[0037] When antenna 10 performs at least one of transmission and reception, electromagnetic waves pass through metalens 20. As the electromagnetic waves pass through metalens 20, the phase of the RF signal is adjusted according to the shape and arrangement of pattern 23. For example, electromagnetic waves transmitted by antenna 10 are converted from a spherical wavefront to a planar wavefront by metalens 20, thereby increasing the EIRP (equivalent isotropically radiated power) and enabling communication over longer distances. When antenna 10 receives electromagnetic waves, metalens 20 can concentrate the electromagnetic waves on antenna 10, thereby improving reception sensitivity. The phase of the RF signal of the electromagnetic waves can be adjusted, for example, by adjusting the outer dimension L1 of main portion 24 (see FIG. 5 ).

[0038] The antenna device 100 can be used as an antenna device for communications in the field of IoT (Internet of Things) or high-speed wireless communications such as WiGig (Wireless Gigabit).

[0039] [Effects of the Antenna Device of the First Embodiment] The antenna device 100 of the present embodiment includes an antenna 10 and a metalens 20. The metalens 20 includes a plurality of unit cells 21 arranged two-dimensionally. Each unit cell 21 has a plurality of lens layers 22 and a pattern 23 formed on the lens layer 22. In the antenna device 100, when an electromagnetic wave passes through the metalens 20, the phase of the RF signal is adjusted according to the shape and arrangement of the pattern 23. This makes it possible to improve the transmission and reception characteristics of the antenna 10. For example, the EIRP (equivalent isotropically radiated power) and sensitivity of the electromagnetic wave can be improved.

[0040] In the antenna device 100, the pattern 23 in the unit cell 21 includes the main portion 24 and the annular portion 25, which makes it easier to adjust the phase of the RF signal of the electromagnetic wave.

[0041] In the metalens 20, the unit cells 21 form a plurality of multiple annular cell groups 27. This reduces the circumferential bias of the electromagnetic waves, thereby improving the transmission and reception characteristics.

[0042] The unit cell 21 can be easily fabricated by forming the pattern 23 on one surface of the lens layer 22 by an additive method or the like, thereby facilitating the manufacture of the antenna device 100.

[0043] [First Modification of Unit Cell] Figure 6 is a plan view of a unit cell 121, which is a first modification of the unit cell 21. Components common to the unit cell 21 (see Figure 5) are designated by the same reference numerals and will not be described again. As shown in Figure 6, the unit cell 121 has a pattern 123 instead of the pattern 23. The pattern 123 includes a main portion 124 and an annular portion 25 surrounding the main portion 124. The main portion 124 has six extension portions 126 extending radially from the center. The main portion 124 has a shape that is six-fold symmetric (60° symmetric) with the center of the main portion 124 as the axis.

[0044] A metalens having unit cells 121 may provide different transmission and reception characteristics than metalens 20 (see FIG. 1) having unit cells 21.

[0045] [Second Modification of Unit Cell] Figure 7 is a plan view of a unit cell 221, which is a second modification of the unit cell 21. Components common to the unit cell 121 (see Figure 6) are designated by the same reference numerals and will not be described again. As shown in Figure 7, the unit cell 221 has a pattern 223 instead of the pattern 123 (see Figure 6). The pattern 223 has a main portion 224 instead of the main portion 124 (see Figure 6). The main portion 224 differs from the main portion 124 (see Figure 6) in that it has an opening 224a in the center. The opening 224a is, for example, circular.

[0046] A metalens having unit cells 221 may provide different transmission and reception characteristics than a metalens having unit cells 121 (see FIG. 6 ).

[0047] [Antenna Device] (Second Embodiment) FIG. 8 is a cross-sectional view of an antenna device 200 according to a second embodiment. Components common to the antenna device 100 (see FIG. 2) are designated by the same reference numerals, and descriptions thereof will be omitted. As shown in FIG. 8 , the antenna device 200 includes an antenna 10, a metalens 120, a main body 30, and an exterior body 140. The exterior body 140 differs from the exterior body 40 (see FIG. 2) in that no opening is formed in the front plate 142. The first lens layer 22A of the metalens 120 is provided on the front surface of the front plate 142. The second lens layer 22B is provided on the rear surface of the front plate 142.

[0048] Antenna device 200 has no opening in front plate 142, which increases the strength of exterior body 140. Therefore, antenna device 200 is excellent in terms of mechanical strength.

[0049] [Antenna Device] (Third Embodiment) FIG. 9 is a cross-sectional view of an antenna device 300 according to a third embodiment. Components common to the antenna device 100 (see FIG. 2) are designated by the same reference numerals, and descriptions thereof will be omitted. As shown in FIG. 9 , the antenna device 300 includes an antenna 10, a plurality of metalenses 220, a main body 30, and an exterior body 240. The exterior body 240 has a front plate 242 formed in a curved convex shape (e.g., an arc-shaped cross section) that is convex toward the front. The first lens layer 22A of the metalens 220 is provided on the front surface of the front plate 242. The second lens layer 22B is provided on the rear surface of the front plate 242.

[0050] In the antenna device 300, the front plate 242 is curved and convex, so the distance between the antenna 10 and the metalens 220 can be made uniform, thereby achieving excellent transmission and reception characteristics.

[0051] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the number of lens layers constituting the unit cell may be any number equal to or greater than two.

[0052] Furthermore, within the scope of the present invention, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate.

[0053] 10...antenna, 20, 120, 220...metalens, 21, 121, 221...unit cell, 22...lens layer, 23, 123, 223...pattern, 24, 124, 224...main portion, 26, 126...extension portion, 25...annular portion, 27...annular cell group, 100, 200, 300...antenna device, L1...outside dimension

Claims

1. An antenna device comprising: an antenna that at least one of transmits and receives electromagnetic waves; and a metalens through which the electromagnetic waves pass, wherein the metalens has a plurality of unit cells arranged two-dimensionally, each of the plurality of unit cells having a plurality of lens layers arranged to overlap in a planar view, and a conductive pattern formed on each of the plurality of lens layers.

2. The antenna device according to claim 1, wherein the pattern comprises a main portion and an annular portion surrounding the main portion.

3. The antenna device according to claim 2, wherein the outer dimensions of the main part are determined according to the distance from the antenna to the pattern.

4. The antenna device according to claim 2, wherein the main portion has a shape including a plurality of extending portions extending radially from a center.

5. The antenna device according to any one of claims 1 to 4, wherein the plurality of unit cells form a plurality of annular cell groups arranged in a ring shape, and the plurality of annular cell groups are arranged in multiple rings.

6. The antenna device according to any one of claims 1 to 4, wherein the lens layer is made of a dielectric substrate, and the pattern is formed on one surface of the dielectric substrate.

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