Array antenna

Abstract

This array antenna includes a plurality of antenna parts arranged in an array. The antenna unit comprises a substrate having a first surface, openings provided in an array on the first surface of the substrate, and a plurality of via conductors formed around each of the plurality of openings. In plan view as seen from a direction perpendicular to the first surface, at least some of the plurality of via conductors aligned in a first direction around the openings are disposed so as to be offset in the first direction or a second direction orthogonal to the first direction on the first surface with respect to a reference position.

Description

Array antenna

[0001] The present disclosure relates to array antennas.

[0002] Patent Document 1 describes a stacked aperture antenna that is applicable to a wide band.

[0003] Patent No. 3420474

[0004] The array antenna of the present disclosure includes a plurality of antenna units arranged in an array, each of which comprises a substrate having a first surface, openings arranged in an array on the first surface of the substrate, and a plurality of via conductors formed around each of the openings, and in a planar view viewed from a direction perpendicular to the first surface, at least some of the via conductors arranged in a first direction around the openings are shifted relative to a reference position in the first direction or in a second direction perpendicular to the first direction on the first surface.

[0005] FIG. 1 is a diagram illustrating an example of the configuration of an antenna according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of an antenna unit according to an embodiment. FIG. 3 is a diagram illustrating a method of arranging via conductors in an antenna unit according to a comparative example of the embodiment. FIG. 4 is a diagram illustrating a method of arranging via conductors in an array antenna according to a comparative example of the embodiment. FIG. 5 is a diagram illustrating issues of the embodiment. FIG. 6 is a diagram illustrating issues of the embodiment. FIG. 7 is a diagram illustrating an example of design rules according to an embodiment. FIG. 8 is a diagram illustrating a method of arranging via conductors in an antenna unit according to the first embodiment. FIG. 9 is a diagram illustrating a method of arranging via conductors in an array antenna according to the first embodiment. FIG. 10 is a diagram illustrating the reflection characteristics of an array antenna according to the first embodiment. FIG. 11 is a diagram illustrating a radiation pattern of an array antenna according to the first embodiment. FIG. 12 is a diagram illustrating a radiation pattern of an array antenna according to the first embodiment. FIG. 13 is a diagram illustrating the radiation efficiency of an array antenna according to the first embodiment. FIG. 14 is a diagram illustrating a method of arranging via conductors in an antenna unit according to a second embodiment. FIG. 15 is a diagram illustrating a method of arranging via conductors in an array antenna according to the second embodiment. FIG. 16 is a diagram for explaining a method of arranging via conductors in an antenna portion according to the third embodiment.

[0006] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and in the following embodiments, the same components are designated by the same reference numerals, and redundant explanations will be omitted.

[0007] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ Cartesian coordinate system. The direction parallel to the X axis in a horizontal plane is defined as the X-axis direction, the direction parallel to the Y axis in the horizontal plane perpendicular to the X axis is defined as the Y-axis direction, and the direction parallel to the Z axis perpendicular to the horizontal plane is defined as the Z-axis direction. Furthermore, the plane including the X axis and Y axis will be referred to as the XY plane as appropriate, the plane including the X axis and Z axis will be referred to as the XZ plane as appropriate, and the plane including the Y axis and Z axis will be referred to as the YZ plane as appropriate. The XY plane is parallel to the horizontal plane. The XY plane, XZ plane, and YZ plane are perpendicular to each other.

[0008] (Antenna) A configuration example of an antenna according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing a configuration example of an antenna according to the embodiment.

[0009] As shown in Fig. 1, the antenna 1 includes an antenna unit 10 and a power feed line 20. The antenna unit 10 and the power feed line 20 are integrally configured. In the example shown in Fig. 1, only one antenna unit 10 is shown, but the antenna units 10 may be provided in an array on the power feed line 20.

[0010] 2 is a diagram illustrating an example of the configuration of an antenna unit according to an embodiment. As shown in Fig. 1 and Fig. 2, the antenna unit 10 includes a dielectric layer 11, an opening 12, a plurality of via conductors 13, a slot 14, and a conductor layer 15.

[0011] The dielectric layer 11 extends in the XY plane. The XY plane is also referred to as the first plane. A plurality of dielectric layers 11 are stacked in the Z-axis direction. In FIG. 2, the dielectric layer 11 is shown as being made up of four laminated dielectric layers, namely, dielectric layer 11-1, dielectric layer 11-2, dielectric layer 11-3, and dielectric layer 11-4, but the present disclosure is not limited to this. The number of laminated dielectric layers 11 may be three or less, or may be five or more. The dielectric layer 11 is formed of a dielectric material. The dielectric layer 11 is also referred to as a dielectric substrate. The dielectric layer 11 is a dielectric film. The dielectric layer 11 is, for example, a dielectric film formed of an olefin resin-based film material.

[0012] The opening 12 is provided across multiple dielectric layers 11. The opening 12 has a shape with multiple curved portions when viewed in a plan view of the XY plane. Details of the shape of the opening 12 will be described later. Electromagnetic waves are radiated from the opening 12.

[0013] The plurality of via conductors 13 are formed along the stacking direction of each dielectric layer 11. The plurality of via conductors 13 are formed around the opening 12. The plurality of via conductors 13 are configured to surround the opening 12. The plurality of via conductors 13 are formed of a conductive material. The plurality of via conductors 13 are electromagnetically connected to each other by conductor layers 15. It is preferable that the maximum spacing between the plurality of via conductors 13 be, for example, about ¼ of the wavelength of the radio waves used by the antenna unit 10 for communication, so as to prevent electromagnetic wave leakage.

[0014] The antenna section 10 can be said to be a box-shaped resonator without a lid. The side walls of the opening 12 of the antenna section 10 are formed by a plurality of via conductors 13 and a conductor layer 15.

[0015] The slot 14 is provided at a position where it is in contact with at least the feed line 20. In the example shown in Fig. 2, the slot 14 is provided in the dielectric layer 11-4.

[0016] The conductor layer 15 extends in the XY plane. The conductor layer 15 is formed of a metal such as copper. The conductor layer 15 is provided, for example, on the upper surface of the antenna unit 10. The conductor layer 15 is provided, for example, between the dielectric layer 11 and another dielectric layer 11 adjacent to the dielectric layer 11.

[0017] The power feed line 20 includes a dielectric layer 21, a plurality of via conductors 22, a conductor layer 25, and a slot 24. The power feed line 20 transmits electromagnetic waves in the stacking direction of the dielectric layer 21 (the Z-axis direction).

[0018] The dielectric layers 21 are stacked in the Z-axis direction. The dielectric layers 21 are made of a dielectric material. For example, the dielectric layers 21 are made of the same dielectric material as the dielectric layers 11. The dielectric layers 21 are dielectric films. A conductor layer made of a conductive material is provided between the dielectric layers 21.

[0019] The via conductors 22 are formed along the lamination direction of the dielectric layers 21. The via conductors 22 are electromagnetically connected to the corresponding via conductors 13.

[0020] The conductor layer 25 extends in the XY plane. The conductor layer 25 is formed of a metal such as copper. The conductor layer 25 is provided, for example, on the upper surface of the power feed path 20. The conductor layer 25 is provided, for example, between the dielectric layer 21 and the dielectric layer 11 adjacent to the dielectric layer 21.

[0021] The slot 24 is provided at a position where it contacts at least the antenna section 10 .

[0022] The antenna section 10 and the power feed line 20 are electromagnetically connected via the slot 14 and the slot 24 .

[0023] [Method of arranging via conductors in a comparative example] (Antenna unit according to a comparative example) A method of arranging via conductors in an antenna unit according to a comparative example of the embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining a method of arranging via conductors in an antenna unit according to a comparative example of the embodiment.

[0024] FIG. 3 is a top view of an antenna unit 10a according to a comparative example, viewed from a direction perpendicular to the XY plane. This comparative example illustrates a method for arranging multiple via conductors 13 in an antenna unit 10a that communicates using millimeter-wave radio waves. As shown in FIG. 3 , multiple via conductors 13 are arranged in a rectangular shape around an opening 12a in the antenna unit 10a. In the example shown in FIG. 3 , the via conductors 13 aligned in the X-axis direction are aligned in a straight line. The via conductors 13 aligned in the Y-axis direction are aligned in a straight line. In this case, the distance L1 between the ends of the via conductors 13 aligned in the X-axis direction is 6.0 mm, and the distance L2 between the ends of the via conductors 13 aligned in the Y-axis direction is 5.1 mm.

[0025] (Array antenna according to comparative example) A method of arranging via conductors in an array antenna according to a comparative example of the embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram for explaining a method of arranging via conductors in an array antenna according to a comparative example of the embodiment.

[0026] Figure 4 is a top view of an array antenna 100a according to a comparative example, as viewed from a direction perpendicular to the XY plane. In the example shown in Figure 4, the array antenna 100a includes antenna units 10a-1, 10a-2, 10a-3, and 10a-4 arranged in an array. In the example shown in Figure 4, the distance L3 between the antenna units 10a-1 and 10a-2, which are aligned in the X-axis direction, is 6.0 mm. The distance L4 between the antenna units 10a-1 and 10a-3, which are aligned in the Y-axis direction, is 6.0 mm.

[0027] 3 and 4, the diameter of the via conductor 13 is 0.07 mm, and the design rule requires a spacing of at least 0.12 mm between the via conductors 13. In the comparative example, the diameter of the via conductors 13 and the spacing between the via conductors 13 that can be produced are smaller than the size of the antenna portion 10, making it possible to achieve a design that is close to ideal.

[0028] (Problems of the embodiment) Problems of the embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 are diagrams for explaining the problems of the embodiment.

[0029] Fig. 5 is a top view of the antenna unit 10b, viewed from a direction perpendicular to the XY plane, for explaining the problem of the embodiment. The example shown in Fig. 5 shows a method for arranging a plurality of via conductors 13 in the antenna unit 10b, which communicates using radio waves in the sub-terahertz wave band (100 to 300 GHz band). As shown in Fig. 5, in the antenna unit 10b, the plurality of via conductors 13 are arranged in a rectangular shape around the opening 12b.

[0030] The antenna unit 10b used in the sub-terahertz wave band is smaller in size than the antenna unit 10a (see FIG. 3) used in the millimeter wave band. Here, in the antenna unit 10b, the diameter of the via conductors 13, the spacing between the via conductors 13, and the minimum value of the via land are determined by design rules. FIG. 7 is a diagram for explaining an example of the design rules according to the embodiment. FIG. 7 shows a method for arranging the via conductors 13 as viewed perpendicularly to the XY plane. In the example shown in FIG. 7, the design rules stipulate that, when the substrate of the antenna unit 10b is made of a resin material, the diameter D1 of the via conductors 13 is 0.07 mm or more, the spacing D2 between the via conductors 13 is 0.12 mm or more, and the distance from the edge of the via conductor 13 to the edge of the via land 16 is 0.04 mm or more.

[0031] Returning to Fig. 5, the antenna unit 10b includes a via conductor group 30b-1, a via conductor group 30b-2, a via conductor group 40b-1, and a via conductor group 40b-2, each of which is configured with a plurality of via conductors 13.

[0032] The via conductor group 30b-1 and the via conductor group 30b-2 include a plurality of via conductors 13 aligned on a straight line parallel to the X-axis direction. The via conductor group 40b-1 and the via conductor group 40b-2 include a plurality of via conductors 13 aligned on a straight line parallel to the Y-axis direction. In the antenna unit 10b, the distance L5 from end to end of the via conductors 13 aligned in the X-axis direction is 0.6 mm, and the distance L2 from end to end of the via conductors 13 aligned in the Y-axis direction is 0.51 mm. Even in the sub-terahertz waveband, the antenna unit 10b alone can be designed to be close to ideal. In this disclosure, the example shown in FIG. 5 is referred to as the reference position of the via conductors 13.

[0033] Fig. 6 is a top view of the array antenna 100b for explaining the problem, as viewed from a direction perpendicular to the XY plane. In the example shown in Fig. 6, the array antenna 100b includes antenna sections 10b-1, 10b-2, 10b-3, and 10b-4 arranged in an array. The array antenna 100b includes via conductor group 31b, via conductor group 32b, via conductor group 33b, via conductor group 34b, via conductor group 41b, via conductor group 42b, via conductor group 43b, via conductor group 44b, via conductor group 45b, and via conductor group 46b, each of which is composed of a plurality of via conductors 13.

[0034] Via conductor group 31b to via conductor group 34b include a plurality of via conductors 13 arranged on a straight line parallel to the X-axis direction. The via conductors 13 included in via conductor group 32b and the via conductors 13 included in via conductor group 34b face each other in the Y-axis direction.

[0035] The via conductor groups 41b to 46b each have a plurality of via conductors 13 arranged on a straight line parallel to the Y-axis direction. Each via conductor 13 included in the via conductor group 42b is shared by the antenna portion 10b-1 and the antenna portion 10b-2. Each via conductor 13 included in the via conductor group 45b is shared by the antenna portion 10b-3 and the antenna portion 10b-4.

[0036] In the array antenna 100b, the distance L7 between the antenna units 10b-1 and 10b-2, which are arranged in the X-axis direction, is 0.6 mm. The distance L8 between the antenna units 10b-1 and 10b-3, which are arranged in the Y-axis direction, is 0.6 mm. In this case, the distance between the via conductors 13 included in the via conductor group 32b and the via conductors 13 included in the via conductor group 33b can be 0.09 mm. Because the distance between the via conductors 13 must be at least 0.12 mm, the example shown in FIG. 6 does not satisfy the design rules, and some of the distances between the via conductors 13 are smaller than the minimum value. Therefore, in sub-terahertz waveband antennas, it is necessary to devise a method for arranging the via conductors 13 so as to satisfy the design rules.

[0037] [First embodiment] (Antenna unit according to first embodiment) A method for arranging via conductors in the antenna unit according to the first embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram for explaining a method for arranging via conductors in the antenna unit according to the first embodiment.

[0038] FIG. 8 is a top view of the antenna unit 10 according to the first embodiment, as viewed from a direction perpendicular to the XY plane. The first embodiment illustrates a method for arranging multiple via conductors 13 in the antenna unit 10, which communicates using radio waves in the sub-terahertz wave band. As shown in FIG. 8, the antenna unit 10 includes via conductor groups 30-1, 30-2, 40-1, and 40-2, each of which is configured with multiple via conductors 13. In the example shown in FIG. 8, the multiple via conductors 13 included in the via conductor groups 30-1 and 30-2 are not arranged in a straight line. In FIG. 8, the X-axis direction is parallel to the H-plane, which is parallel to the magnetic field direction, and the Y-axis direction is parallel to the E-plane, which is parallel to the electric field direction. The X-axis direction is also referred to as the first direction, and the Y-axis direction is also referred to as the second direction.

[0039] In the via conductor group 30-1, at least some of the via conductors 13 are arranged offset from a single straight line parallel to the X-axis direction in planar view in the XY plane. Specifically, the via conductors 13-2 and 13-4 are arranged offset in the -Y-axis direction from a single straight line in planar view in the XY plane. In this case, the via conductors 13-1, 13-3, and 13-5 are aligned on the same straight line parallel to the X-axis direction in planar view in the XY plane. The via conductors 13-2 and 13-4 are aligned on the same straight line parallel to the X-axis direction in planar view in the XY plane. In other words, the via conductor group 30-1 can be said to have a plurality of via conductor groups aligned on a plurality of different straight lines parallel to the X-axis direction.

[0040] In the via conductor group 30-2, at least some of the via conductors 13 are arranged offset from a single straight line parallel to the X-axis direction in planar view in the XY plane. Specifically, the via conductors 13-7 and 13-8 are arranged offset in the +Y-axis direction from a single straight line in planar view in the XY plane. In this case, the via conductors 13-6, 13-8, and 13-10 are aligned on the same straight line parallel to the X-axis direction in planar view in the XY plane. The via conductors 13-7 and 13-9 are aligned on the same straight line parallel to the X-axis direction in planar view in the XY plane. In other words, the via conductor group 30-2 can be said to have a plurality of via conductor groups aligned on a plurality of different straight lines parallel to the X-axis direction.

[0041] The via conductor group 40-1 and the via conductor group 40-2 each have a plurality of via conductors 13 arranged on the same straight line parallel to the Y-axis direction.

[0042] The distance L10 between the via conductors 13 included in the via conductor group 40-1 and the via conductors 13 included in the via conductor group 40-2 is 0.6 mm. The distance L11 between the via conductors 13-1 and 13-6 is 0.48 mm. The distance L12 between the via conductors 13-2 and 13-7 is 0.6 mm. The distances L10, L11, and L12 are set to achieve a desired resonant frequency. In the antenna unit 10a, the distance between the via conductors 13 can be 0.12 mm or more. In other words, the antenna unit 10a can satisfy the design rules.

[0043] In the first embodiment, the opening 12 has a shape having a plurality of curved portions. The opening 12 has a rotationally symmetric shape in a planar view of the XY plane. The opening 12 is formed by providing curved portions in a rectangular opening. The opening 12 has 12 curved portions from curved portion 15a to curved portion 15l.

[0044] Curved portion 15a is provided on the upper side of opening 12. Curved portion 15b is provided in the upper right corner of opening 12. Curved portion 15c, curved portion 15d, and curved portion 15e are provided on the right side of opening 12. Curved portion 15f is provided in the lower right corner. Curved portion 15g is provided on the lower side of opening 12. Curved portion 15h is provided in the lower left corner of opening 12. Curved portion 15i, curved portion 15j, and curved portion 15k are provided on the left side of opening 12. Curved portion 15l is provided in the upper left corner of opening 12.

[0045] Curved portions 15a to 15l are curved portions that protrude inward of opening 12. Although opening 12 is shown as having 12 curved portions, the present disclosure is not limited thereto. Since the resonant frequency of antenna unit 10 deviates from the initial design value depending on the arrangement of via conductors 13, opening 12 may have curved portions provided so as to match the resonant frequency to the design value. Each curved portion may be provided, for example, so that opening 12 has a rotationally symmetric shape in plan view on the XY plane. This allows antenna unit 10 to satisfy its characteristics.

[0046] (Array antenna according to the first embodiment) A method for arranging via conductors in the array antenna according to the first embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram for explaining a method for arranging via conductors in the array antenna according to the first embodiment.

[0047] Fig. 9 is a top view of the array antenna 100 according to the first embodiment, as viewed from the perpendicular direction of the XY plane. In the example shown in Fig. 9, the array antenna 100 includes an antenna unit 10-1, an antenna unit 10-2, an antenna unit 10-3, and an antenna unit 10-4 arranged in an array. Power is supplied to each of the antenna units 10-1 to 10-4 from a power feed line 20 (see Fig. 1).

[0048] In the example shown in Fig. 9, the antenna units 10 are arranged in an array. The array antenna 100 shown in Fig. 9 includes via conductor group 31, via conductor group 32, via conductor group 33, via conductor group 34, via conductor group 41, via conductor group 42, via conductor group 43, via conductor group 44, via conductor group 45, and via conductor group 46, each of which is configured with a plurality of via conductors 13.

[0049] The via conductor group 31 includes via conductors 13-11 to 13-20. In the via conductor group 31, at least some of the via conductors 13 are arranged offset from a single straight line in a planar view of the XY plane. Specifically, the via conductors 13-12, 13-14, 13-17, and 13-19 are arranged offset in the -Y-axis direction from a single straight line in a planar view of the XY plane. In this case, the via conductors 13-11, 13-13, 13-15, 13-16, 13-18, and 13-20 are aligned on the same straight line parallel to the X-axis direction in a planar view of the XY plane. The via conductors 13-12, 13-14, 13-17, and 13-19 are aligned on the same straight line parallel to the X-axis direction in a planar view of the XY plane. In other words, the via conductor group 31 can be said to have a plurality of via conductor groups arranged on a plurality of different straight lines parallel to the X-axis direction.

[0050] The via conductor group 32 includes via conductors 13-21 to 13-30. In the via conductor group 32, at least some of the via conductors 13 are arranged offset from a single straight line in a planar view of the XY plane. Specifically, the via conductors 13-22, 13-24, 13-27, and 13-29 are arranged offset in the +Y-axis direction from a single straight line in a planar view of the XY plane. In this case, the via conductors 13-21, 13-23, 13-25, 13-26, 13-28, and 13-30 are aligned on the same straight line parallel to the X-axis direction in a planar view of the XY plane. The via conductors 13-22, 13-24, 13-27, and 13-29 are aligned on the same straight line parallel to the X-axis direction in a planar view of the XY plane. In other words, the via conductor group 32 can be said to have a plurality of via conductor groups arranged on a plurality of different straight lines parallel to the X-axis direction.

[0051] The via conductor group 33 includes via conductors 13-22, 13-24, 13-27, 13-29, 13-31, 13-32, 13-33, 13-34, 13-35, and 13-36. That is, the via conductors 13-22, 13-24, 13-27, and 13-29 are via conductors 13 included in the via conductor group 32 and the via conductor group 33.

[0052] In the via conductor group 33, at least some of the via conductors 13 are arranged offset from a straight line in the XY plane. Specifically, the via conductors 13-22, 13-24, 13-27, and 13-29 are arranged offset in the -Y-axis direction from a single straight line in the XY plane. In this case, the via conductors 13-22, 13-24, 13-27, and 13-29 are aligned on the same straight line parallel to the X-axis direction in the XY plane. The via conductors 13-31, 13-32, 13-33, 13-34, 13-35, and 13-36 are aligned on the same straight line parallel to the X-axis direction in the XY plane. In other words, the via conductor group 33 can be said to have a plurality of via conductor groups aligned on a plurality of different straight lines parallel to the X-axis direction.

[0053] The via conductors 13-21 and 13-31 face each other in the Y-axis direction. The via conductors 13-23 and 13-32 face each other in the Y-axis direction. The via conductors 13-25 and 13-33 face each other in the Y-axis direction. The via conductors 13-26 and 13-34 face each other in the Y-axis direction. The via conductors 13-28 and 13-35 face each other in the Y-axis direction. The via conductors 13-30 and 13-36 face each other in the Y-axis direction.

[0054] The via conductor group 34 includes via conductors 13-37 to 13-46. In the via conductor group 34, at least some of the via conductors 13 are arranged offset from a straight line in the XY plane. Specifically, the via conductors 13-38, 13-40, 13-43, and 13-45 are arranged offset in the +Y-axis direction from a straight line in the XY plane. In this case, the via conductors 13-37, 13-39, 13-41, 13-42, 13-44, and 13-46 are aligned on a straight line parallel to the X-axis direction in the XY plane. The via conductors 13-38, 13-40, 13-43, and 13-45 are aligned on the same straight line parallel to the X-axis direction in the XY plane. In other words, the via conductor group 30-4 can be said to have a plurality of via conductor groups arranged on a plurality of different identical straight lines parallel to the X-axis direction.

[0055] Each of the via conductor groups 41 to 46 has a plurality of via conductors 13 arranged on the same straight line parallel to the Y-axis direction. Each of the via conductors 13 included in the via conductor group 42 is shared by the antenna unit 10-1 and the antenna unit 10-2. Each of the via conductors 13 included in the via conductor group 45 is shared by the antenna unit 10-3 and the antenna unit 10-4. Note that the via conductor group 42 may include a plurality of via conductors 13 for the antenna unit 10-1 and a plurality of via conductors 13 for the antenna unit 10-2.

[0056] 9, the shortest distances between adjacent via conductors 13 in the X-axis direction are between the via conductors 13-15 and 13-16, between the via conductors 13-25 and 13-26, between the via conductors 13-33 and 13-34, and between the via conductors 13-41 and 13-42. The distances between these via conductors 13 can be set to 0.12 mm.

[0057] 9, the shortest distances between adjacent via conductors 13 in the Y-axis direction are between the via conductors 13-21 and 13-31, between the via conductors 13-23 and 13-32, between the via conductors 13-25 and 13-33, between the via conductors 13-26 and 13-34, between the via conductors 13-28 and 13-35, and between the via conductors 13-30 and 13-36. The distances between these via conductors 13 can be set to 0.12 mm.

[0058] 9, the distance between the via conductors 13 can be set to 0.12 mm or more. That is, the first embodiment can realize an array antenna 100 that satisfies the design rules.

[0059] [Reflection Characteristics] The reflection characteristics of the array antenna according to the first embodiment will be described with reference to Fig. 10. Fig. 10 is a diagram for explaining the reflection characteristics of the array antenna according to the first embodiment.

[0060] In Fig. 10, the horizontal axis represents frequency [GHz], and the vertical axis represents the S parameter S11 (reflection characteristic) [dB]. The smaller the S11 value, the more the signal passes through the array antenna 100. Waveform 201 represents the reflection characteristic of the array antenna 100. In the example shown in Fig. 10, the operating band of the array antenna 100 is assumed to be 250 [GHz] to 300 [GHz].

[0061] As shown in the waveform 200, the reflection characteristic of the array antenna 100 is −13 dB or less in the operating band of 250 GHz to 300 GHz. In other words, the array antenna 100 has good reflection characteristics in the operating band of 250 GHz to 300 GHz.

[0062] [Radiation Pattern] (Radiation Pattern of E-Plane) The radiation pattern of the array antenna according to the first embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram for explaining the radiation pattern of the array antenna according to the first embodiment.

[0063] 11, the horizontal axis represents the radiation angle [degrees] and the vertical axis represents the gain [dB]. Waveform 202 represents the radiation pattern of the E-plane of the array antenna 100. As shown by waveform 202, in the E-plane, the gain is 3 [dB] or more when the radiation angle is in the range of -90 degrees to 90 degrees. As shown by waveform 202, the array antenna 100 has good radiation characteristics in the E-plane.

[0064] (Radiation Pattern of H Plane) The radiation pattern of the array antenna according to the first embodiment will be described with reference to Fig. 12. Fig. 12 is a diagram for explaining the radiation pattern of the array antenna according to the first embodiment.

[0065] In Fig. 12, the horizontal axis represents the radiation angle [degrees] and the vertical axis represents the gain [dB]. Waveform 203 represents the radiation pattern of the H plane of the array antenna 100. As shown in waveform 203, the radiation pattern of the H plane has a maximum gain of 5 [dB] when the radiation angle is 0 degrees. As shown in waveform 203, the gain of the radiation pattern of the H plane gradually decreases as the radiation angle moves away from 0 degrees. As shown in waveform 203, the array antenna 100 has good radiation characteristics in the H plane.

[0066] [Radiation Efficiency] The radiation efficiency of the array antenna according to the first embodiment will be described with reference to Fig. 13. Fig. 13 is a diagram for explaining the radiation efficiency of the array antenna according to the first embodiment.

[0067] 13, the horizontal axis represents frequency [GHz] and the vertical axis represents radiation efficiency [%]. Waveform 204 represents the radiation efficiency of the array antenna 100. As shown by waveform 204, the array antenna 100 exhibits a radiation efficiency of 75% or more in the operating band of 250 GHz to 300 GHz. In other words, the array antenna 100 has good radiation characteristics in the operating region.

[0068] [Second embodiment] (Antenna unit according to second embodiment) A method for arranging via conductors in an antenna unit according to a second embodiment will be described with reference to Fig. 14. Fig. 14 is a diagram for explaining a method for arranging via conductors in an antenna unit according to the second embodiment.

[0069] FIG. 14 is a top view of an antenna unit 10A according to the second embodiment, as viewed from a direction perpendicular to the XY plane. The first embodiment illustrates a method for arranging multiple via conductors 13A in an antenna unit 10A that communicates using radio waves in the sub-terahertz wave band. As shown in FIG. 14, the antenna unit 10A includes a via conductor group 30A-1, a via conductor group 30A-2, a via conductor group 40A-1, and a via conductor group 40A-2, each of which is configured with multiple via conductors 13A. In the example shown in FIG. 14, the via conductor group 30A-1 and the via conductor group 30A-2 each have multiple via conductors 13A aligned on the same line parallel to the X-axis direction. The via conductor group 40A-1 and the via conductor group 40A-2 each have multiple via conductors 13A aligned on the same line parallel to the Y-axis direction.

[0070] In the via conductor group 30A-1, in plan view in the XY plane, each via conductor 13A is arranged offset from a reference position along the same straight line parallel to the X-axis direction in the XY plane. Specifically, each via conductor 13A included in the via conductor group 30A-1 is arranged offset from the reference position in the −X-axis direction.

[0071] In the via conductor group 30A-2, in plan view in the XY plane, each via conductor 13A is arranged offset along the same straight line parallel to the X-axis direction with respect to a reference position. Specifically, each via conductor 13A included in the via conductor group 30A-2 is arranged offset in the +X-axis direction with respect to the reference position.

[0072] The via conductor group 40-1A and the via conductor group 40A-2 each have a plurality of via conductors 13A arranged on the same straight line parallel to the Y-axis direction.

[0073] The distance L20 between the via conductors 13 included in the via conductor group 40A-1 and the via conductors 13A included in the via conductor group 40A-2 is 0.6 mm. The distance L21 between the via conductors 13A included in the via conductor group 30A-1 and the via conductors 13A included in the via conductor group 30A-2 is 0.51 mm. In the antenna section 10b, the distance between the via conductors 13 can be 0.12 mm or more. In other words, the antenna section 10b can satisfy the design rules.

[0074] In the second embodiment, the opening 12A has a shape with multiple curved portions. The opening 12A has a rotationally symmetric shape in a planar view of the XY plane. The opening 12 is formed by providing curved portions in a rectangular opening. The opening 12A has 12 curved portions from curved portion 15Aa to curved portion 15AK.

[0075] Curved portions 15Aa, 15Ab, and 15Ac are provided on the upper side of opening 12A. Curved portions 15Ad, 15Ae, and 15Af are provided on the left side of opening 12A. Curved portions 15Ag, 15Ah, and 15Ai are provided on the lower side of opening 12A. Curved portions 15Aj, 15Ak, and 15Al are provided on the left side of opening 12A.

[0076] Curved portions 15Aa to 15Al are curved portions that protrude inward of opening 12A. Although opening 12A is shown as having 12 curved portions, the present disclosure is not limited thereto. Since the resonant frequency of antenna unit 10A deviates from the initial design value due to the arrangement of via conductors 13, opening 12A may have curved portions provided to match the resonant frequency to the design value. Each curved portion may be provided, for example, so that opening 12A has a rotationally symmetric shape in plan view on the XY plane. This allows antenna unit 10A to satisfy its characteristics.

[0077] (Array antenna according to second embodiment) A method for arranging via conductors in an array antenna according to the second embodiment will be described with reference to Fig. 15. Fig. 15 is a diagram for explaining a method for arranging via conductors in an array antenna according to the second embodiment.

[0078] Fig. 15 is a top view of the array antenna 100A according to the second embodiment, as viewed from the perpendicular direction of the XY plane. In the example shown in Fig. 15, the array antenna 100A includes an antenna unit 10A-1, an antenna unit 10A-2, an antenna unit 10A-3, and an antenna unit 10A-4 arranged in an array.

[0079] In the example shown in Fig. 15, antenna units 10A are arranged in an array. The array antenna 100A shown in Fig. 15 includes via conductor groups 31A, 32A, 33A, 34A, 41A, 42A, 43A, 44A, 45A, and 46A, each of which is configured with a plurality of via conductors 13A.

[0080] The via conductor group 31A includes via conductors 13A-1 to 13A-8. In plan view of the XY plane, the via conductors 13A-1 to 13A-8 are arranged offset from a reference position along the same straight line parallel to the X-axis direction. Specifically, the via conductors 13A-1 to 13A-8 are arranged offset from the reference position in the +X-axis direction.

[0081] The via conductor group 32A includes via conductors 13A-9 to 13A-16. In plan view of the XY plane, the via conductors 13A-9 to 13A-16 are arranged offset from a reference position along the same straight line parallel to the X-axis direction. Specifically, the via conductors 13A-9 to 13A-16 are arranged offset from the reference position in the −X-axis direction.

[0082] The via conductor group 33A includes via conductors 13A-17 to 13A-24. In plan view of the XY plane, the via conductors 13A-17 to 13A-24 are arranged offset from a reference position along the same straight line parallel to the X-axis direction. Specifically, the via conductors 13A-17 to 13A-24 are arranged offset from the reference position in the +X-axis direction.

[0083] The via conductor 13A-9 to the via conductor 13A-16 and the via conductor 13A-17 to the via conductor 13A-24 are offset in opposite directions, so the via conductor 13A-9 to the via conductor 13A-16 and the via conductor 13A-17 to the via conductor 13A-24 do not face each other in the Y-axis direction.

[0084] The via conductor group 34A includes via conductors 13A-25 to 13A-32. In plan view of the XY plane, the via conductors 13A-25 to 13A-32 are arranged offset from a reference position along the same straight line parallel to the X-axis direction. Specifically, the via conductors 13A-25 to 13A-32 are arranged offset from the reference position in the −X-axis direction.

[0085] Each of the via conductor groups 41A to 46A has a plurality of via conductors 13A arranged on the same straight line parallel to the Y-axis direction. Each of the via conductors 13A included in the via conductor group 42A is shared by the antenna unit 10A-1 and the antenna unit 10A-2. Each of the via conductors 13 included in the via conductor group 45A is shared by the antenna unit 10-3 and the antenna unit 10-4. The via conductor group 42A may include a plurality of via conductors 13A for the antenna unit 10A-1 and a plurality of via conductors 13A for the antenna unit 10A-2.

[0086] In the example shown in FIG. 15, the intervals between the via conductors 13A included in the via conductor group 32A and the via conductor group 33A tend to be short.

[0087] The distance between via conductor 13A-10 and via conductor 13A-11, the distance between via conductor 13A-11 and via conductor 13A-12, the distance between via conductor 13A-14 and via conductor 13A-15, the distance between via conductor 13A-15 and via conductor 13A-16, the distance between via conductor 13A-17 and via conductor 13A-18, the distance between via conductor 13A-18 and via conductor 13A-19, and the distance between via conductor 13A-22 and via conductor 13A-23 can be, for example, 160 μm.

[0088] The distance between via conductor 13A-9 and via conductor 13A-10, the distance between via conductor 13A-13 and via conductor 13A-14, the distance between via conductor 13A-19 and via conductor 13A-20, and the distance between via conductor 13A-23 and via conductor 13A-24 can be, for example, 146.5 μm.

[0089] The distance between the via conductors 13A-12 and 13A-13 and the distance between the via conductors 13A-20 and 13A-21 can be set to, for example, 133.5 μm.

[0090] The distance between via conductor 13A-10 and via conductor 13A-17, the distance between via conductor 13A-10 and via conductor 13A-18, the distance between via conductor 13A-11 and via conductor 13A-18, the distance between via conductor 13A-11 and via conductor 13A-19, the distance between via conductor 13A-12 and via conductor 13A-19, the distance between via conductor 13A-14 and via conductor 13A-21, the distance between via conductor 13A-14 and via conductor 13A-22, the distance between via conductor 13A-15 and via conductor 13A-22, the distance between via conductor 13A-15 and via conductor 13A-23, and the distance between via conductor 13A-16 and via conductor 13A-23 can be, for example, 128 μm.

[0091] The distance between via conductor 13A-9 and via conductor 13A-17, the distance between via conductor 13A-12 and via conductor 13A-20, the distance between via conductor 13A-13 and via conductor 13A-20, the distance between via conductor 13A-13 and via conductor 13A-21, and the distance between via conductor 13A-16 and via conductor 13A-24 can be, for example, 120 μm.

[0092] 14, the distance between the via conductors 13 can be set to 0.12 mm or more. That is, the second embodiment can realize an array antenna 100A that satisfies the design rules.

[0093] [Third embodiment] (Antenna unit according to third embodiment) A method for arranging via conductors in an antenna unit according to a third embodiment will be described with reference to Fig. 16. Fig. 16 is a diagram for explaining a method for arranging via conductors in an antenna unit according to the third embodiment.

[0094] 16 is a top view of the antenna unit 10B according to the first embodiment, as viewed from a direction perpendicular to the XY plane. The third embodiment shows a method for arranging multiple via conductors 13B in the antenna unit 10B, which has a ceramic substrate and communicates using radio waves in the sub-terahertz wave band. The antenna unit 10B includes an opening 12B and multiple via conductors 13B formed around the opening 12B. The opening 12B has a rectangular shape, but is not limited to this.

[0095] As shown in Fig. 16, at least a portion of the antenna portion 10B protrudes toward the opening 12B. Specifically, the antenna portion 10B includes via conductors 13B-1, 13B-2, 13B-3, and 13B-4. In the third embodiment, the area of ​​the opening 12B is larger than, for example, the opening 12 (see Fig. 8) and the opening 12A (see Fig. 14). When the antenna portion 10B is made of a ceramic substrate, the characteristics can be improved by configuring the antenna portion 10B in the configuration shown in Fig. 16.

[0096] The present disclosure may also be configured as follows. (1) An array antenna including a plurality of antenna units arranged in an array, the antenna units comprising: a substrate having a first surface; openings provided in an array on the first surface of the substrate; and a plurality of via conductors formed around each of the plurality of openings, wherein, in a plan view seen from a direction perpendicular to the first surface, at least some of the plurality of via conductors arranged in a first direction around the opening are shifted with respect to a reference position in the first direction or in a second direction orthogonal to the first direction on the first surface. (2) The array antenna described in (1), wherein, of the plurality of antenna units, a first antenna unit and a second antenna unit adjacent to the first antenna unit in the first direction share the plurality of via conductors arranged in the second direction. (3) The array antenna described in (1) or (2), wherein the plurality of via conductors arranged in the first direction are shifted with respect to a reference position in the second direction every other via conductor. (4) The array antenna according to (1) or (2), wherein a plurality of via conductors included in a first via conductor group among the plurality of via conductors aligned in the first direction and a plurality of via conductors included in the first via conductor group and a second via conductor group adjacent to the first via conductor group in the second direction do not face each other at least partially in the plan view. (5) The array antenna according to (4), wherein at least some of the via conductors included in the first via conductor group and the second via conductor group are arranged shifted in the second direction with respect to the reference position in the plan view, and a first antenna unit among the plurality of antenna units and a third antenna unit adjacent to the first antenna unit in the second direction share the via conductors shifted in the second direction. (6) The array antenna according to (4), wherein one of the plurality of via conductors included in the first via conductor group and the plurality of via conductors included in the second via conductor group is arranged shifted in the first direction with respect to the reference position.(7) The array antenna according to (6), wherein the plurality of via conductors included in the first via conductor group are arranged shifted in the first direction with respect to the reference position in the plan view, and the plurality of via conductors included in the second via conductor group are arranged shifted in the opposite direction with respect to the reference position with respect to the plurality of via conductors included in the first via conductor group in the plan view. (8) The array antenna according to any one of (1) to (7), wherein the substrate includes a dielectric resin or ceramic. (9) The array antenna according to any one of (1) to (8), wherein the opening has a shape having a plurality of curved portions in the plan view. (10) The array antenna according to any one of (1) to (9), wherein the opening has a rotationally symmetric shape in the plan view.

[0097] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

[0098] REFERENCE SIGNS LIST 1 Antenna 10, 10a, 10b, 10A, 10B Antenna section 100, 100a, 100b, 100A Array antenna 11, 21 Dielectric layer 12 Opening 13, 22 Via conductor 14, 24 Slot 15 Conductor layer 20 Power feed path

Claims

1. An array antenna comprising a plurality of antenna units arranged in an array, the antenna units comprising: a substrate having a first surface; openings arranged in an array on the first surface of the substrate; and a plurality of via conductors formed around each of the plurality of openings, wherein, in a plan view seen from a direction perpendicular to the first surface, at least some of the plurality of via conductors arranged in a first direction around the openings are shifted relative to a reference position in the first direction or in a second direction perpendicular to the first direction on the first surface.

2. An array antenna as described in claim 1, wherein, among the plurality of antenna sections, a first antenna section and a second antenna section adjacent to the first antenna section in the first direction share a plurality of the via conductors aligned in the second direction.

3. An array antenna as described in claim 1 or 2, wherein the via conductors aligned in the first direction are arranged so that every other via conductor is shifted in the second direction with respect to a reference position.

4. An array antenna as described in claim 1, wherein a plurality of via conductors included in a first via conductor group among a plurality of via conductors arranged in the first direction, and a plurality of via conductors included in a second via conductor group adjacent to the first via conductor group in the second direction, are at least partially not opposed to each other in the planar view.

5. An array antenna as described in claim 4, wherein at least some of the via conductors included in the first via conductor group and the second via conductor group are arranged shifted in the second direction relative to the reference position in the planar view, and among the plurality of antenna units, a first antenna unit and a third antenna unit adjacent to the first antenna unit in the second direction share the via conductors arranged shifted in the second direction.

6. An array antenna as described in claim 4, wherein one of the via conductors included in the first via conductor group and the via conductors included in the second via conductor group is positioned offset in the first direction with respect to the reference position.

7. An array antenna as described in claim 6, wherein the plurality of via conductors included in the first via conductor group are arranged, in the planar view, shifted in the first direction relative to the reference position, and the plurality of via conductors included in the second via conductor group are arranged, in the planar view, shifted in the opposite direction to the plurality of via conductors included in the first via conductor group relative to the reference position.

8. The array antenna according to claim 1, wherein the substrate comprises a dielectric resin or ceramic.

9. The array antenna according to claim 1, wherein the opening has a shape having a plurality of curved portions in the plan view.

10. The array antenna according to claim 9, wherein the opening has a rotationally symmetric shape in the plan view.

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